GARY PADGETT'S MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY JULY, 2004 (For general comments about the nature of these summaries, as well as information on how to download the tabular cyclone track files, see the Author's Note at the end of this summary.) ************************************************************************* JULY HIGHLIGHTS --> Northwest Pacific rather quiet while Northeast Pacific heats up ************************************************************************* ***** Feature of the Month for July ***** MONSOON DEPRESSIONS AND STRONG TROPICAL WAVES During the summer (boreal) of 2003, I sent another one of my famous surveys to the members of an informal tropical cyclone discussion group of which I am a member. I also recently sent it to a few other persons in the tropical cyclone community. I intend to present the results of the survey as monthly features spread over several months, beginning with the May, 2004, summary. The survey consisted of ten multiple-choice questions dealing with various tropical or subtropical cyclone-related issues, and two or three questions will be considered each month. The persons responding to the survey are listed below. A special thanks to each for taking the time to respond to the questions. Michael Bath - New South Wales, Australia Bruno Benjamin - Guadeloupe, French West Indies Eric Blake - TPC/NHC, Miami, Florida, USA Pete Bowyer - Canadian Hurricane Centre, Halifax, Nova Scotia, Canada Kevin Boyle - Newchapel Observatory, Stoke-on-Trent, UK Jeff Callaghan - BoM, Brisbane, Queensland, Australia Simon Clarke - Brisbane, Queensland, Australia Tony Cristaldi - NWS Office, Melbourne, Florida, USA Roger Edson - University of Guam, USA Chris Fogarty - Canadian Hurricane Centre, Halifax, Nova Scotia, Canada James Franklin - TPC/NHC, Miami, Florida, USA Bruce Harper - Brisbane, Queensland, Australia Julian Heming - UK Meteorological Office, UK Karl Hoarau - Cergy-Pontoise University, Paris, France Greg Holland - BoM, Australia Mark Kersemakers - BoM, Darwin, Northern Territory, Australia Mark Lander - University of Guam, USA Chris Landsea - AOML/HRD, Miami, Florida, USA Gary Padgett - Alabama, USA Michael V. Padua - Naga City, Philippines Michael Pitt - US Navy David Roberts - TPC/NHC, Miami, Florida, USA David Roth - NOAA/HPC, Maryland, USA Matthew Saxby - Queanbeyan, New South Wales, Australia Carl Smith - Queensland, Australia Phil Smith - Hong Kong, China John Wallace - San Antonio, Texas, USA Ray Zehr - Colorado State University, Ft. Collins, Colorado, USA For each of the survey questions, the format will be as follows: (1) the question as it appeared in the original survey (2) summary of the responses to each of the possible choices (3) some of the comments from various respondents Following this I will attempt to present an analysis of the issues plus interject my opinions on the subject. The monthly feature for July will focus on two types of deep tropical systems, very different from each other, but yet the precursors of the majority of the world's tropical cyclones: the monsoon depression and the tropical wave (also known as easterly waves). Easterly waves are the primary precursor of Atlantic tropical cyclones which form in the deep tropics while monsoon depressions are the parent disturbances for most of the tropical cyclones of the North Indian Ocean, the Northwestern and South Pacific, and the Australian Region. The survey questions dealt specifically with the operational warning problems caused by both monsoon depressions and tropical waves when sustained gale-force winds develop before the appearance of "classic" tropical cyclone characteristics. There were 28 persons who responded to the survey questions. For some questions, certain persons did not specify an answer, so the total number of votes might not always add up to 28. Also, in some cases the respondent was undecided between two of the choices. In those cases I assigned 1/2 vote to each of the two choices. A word about the comments included below: this article is extremely long as it is, and I could not possibly include all the comments which the various respondents made. I have selected certain ones which seem to cover the various issues well, as well as a few which cast a different slant on the question. Question #6 - Monsoon Depressions --------------------------------- (1) The question was: Monsoon depressions are large, sloppily-formed cyclones which are prevalent in the western Pacific (both north and south), Australian Region, and in the Indian Ocean. Sometimes these systems produce winds exceeding gale force, or even storm force, without having a tight circulation nor well-organized central convection. In pre-Dvorak analysis days, no doubt many of these were classified as tropical cyclones. Do you think the best operational warning strategy for monsoon depressions acquiring gale-force winds is: (A) Name as tropical storms (B) Introduce monsoon depression terminology in warnings and emphasize presence of gales (C) Issue gale warnings for certain areas without describing the meteorological phenomenon (D) Ignore and hope they'll go away or else transform into "classic" tropical cyclones (2) Summary of Responses (A) Name as tropical storms: 9.0 votes - 33% (B) Introduce new terminology: 14.5 votes - 54% (C) Issue generic gale warnings: 3.5 votes - 13% (D) Ignore: 0.0 votes - 0% (3) Some Comments Carl Smith (A & B): "They should be named if they are closed systems and produce gale/storm-force winds, however, specific terminology should be included in the warnings describing the situation and where the gales/storm-force winds are expected." Chris Fogarty (C): "Treat it like a large extratropical LOW--like in the Atlantic without getting fancy." Chris Landsea (A): "Handle similarly to what I suggested for sub- tropicals. Name 'em as 'tropical cyclones' operationally, then in the Best Track indicate the best 'true' identity." Dave Roberts (B): "During my tenure at JTWC, I would name monsoon depressions even though core winds were weak. Just was simpler to do without confusing anyone. However, model assimilation was another issue (TC size). Would like to see as separate terminology including monsoon gyres." David Roth (A): "Name as tropical storms since they have a very warm core and usually transition into TCs. Frances of 1998 and Isidore of 2002 fit this definition fine, from what I understand, and completed the transition." Greg Holland (C): "Definitely NOT tropical cyclones...their winds are well removed from what is generally a weakly-defined center (and in the Australian Region often over land), and from memory, a lot, if not most of them, are substantially cold-cored in the lower troposphere...there is actually no need for any changes. My impression is that the current system handles these perfectly well by just putting out gale warnings." James Franklin (B): "Issue gale warnings but discuss in context of a monsoon cyclone." Jeff Callaghan (A): "Justin in the Coral Sea in March, 1997, was for much of its life more like a deep monsoon LOW but had a huge impact at sea." John Wallace (C): "There is no need to add more confusion to the TC classification system by discerning between true TCs and MDs." Julian Heming (B): "If we are going to have a separate terminology for sub-tropical storms in the Atlantic, then there needs to be a similar terminology for monsoon depressions, particularly if winds exceed gale force." Kevin Boyle (B): "Although winds of >35 kts could be classed as a tropical storm, I suppose, to avoid confusion and to enhance aware- ness of the system." Mark Lander (B): I used to think that the most sensible thing to do for monsoon depressions that had evolved to the point of possessing gales was simply to name them as tropical storms. This is still my preferred option, but since the warning agencies seem to have such trouble with these things (center location, the warning format of point-radius, broad light wind center, etc), I think an out is needed. My 'out' would be to develop a point-band or point-ring format for wind distribution. Then the systems can be numbered, and the warning center does not have to over fret the non-standard wind distribution. Also, by the time a MD has true gales in it, it is usually well on its way to becoming a conventional TC anyway." Matthew Saxby (A): "If it's a tropical system with a closed circulation and gales in at least one quadrant, I think the thing should be named and warned on in the normal TC way. Like I said before, any victims aren't going to be impressed with fine legalistic points." Phil Smith (A): "My reason for choosing Option A is purely one of making the general public aware that 'there are dangerous winds about somewhere out there' and that they may need to make preparations for bad weather conditions. As I understand it, this practice is being taken up by BoM for monsoon LOWs threatening Australian areas for this reason. A negative that could be raised against this prac- tice is the likelihood that several circulation centres may develop around the periphery and that these will sometimes 'take turns' at being the dominant centre. This could lead to some exceedingly erratic paths for some storms if the agency concerned tries to fix the centre of the named storm at where the most action is occurring from time to time." Ray Zehr (B or C): "Some 'TC size according to RMW' criteria is needed as a guideline for naming. Since multiple TCs can be associated with a single monsoon depression (or gyre), you can't be naming monsoon depressions. Of course, a monsoon depression can have a TC at its center, i.e., evolve into a TC." Question #7 - Tropical Waves ---------------------------- (1) The question was: Primarily in the Atlantic tradewind belt--perhaps rarely in other basins--well-organized tropical disturbances (i.e., tropical waves) moving rapidly along can produce gale and/or storm- force winds without a closed circulation at the surface. They usually have a mid-level circulation and would no doubt have westerly winds at the surface on the equatorward side if they were not moving so rapidly (sometimes 25-30 kts). These often present a much more serious threat to marine interests and the Lesser Antilles than some "normal" tropical depressions or even weak tropical storms. What is the best operational warning strategy for these? (A) Name as tropical storms (B) Mention that gales are present in Tropical Weather Outlooks or Special Tropical Disturbance Statements (C) Introduce new terminology or issue special advisories for these gale-bearing waves and emphasize warnings for strong winds (2) Summary of Responses (A) Name as tropical storms: 5.5 votes - 20% (B) Mention in TWOs or STDSs: 13.5 votes - 48% (C) New terminology: 9.0 votes - 32% (3) Some Comments Chris Landsea (A or B): "Definitely not Option C, but I'm on the fence about this one. I could see either 'A' or 'B', as long as the best track indicated that they were troughs rather than a tropical cyclone (or even don't include them in the Best Track)." Dave Roberts (C): "Wondering what the statistics are of these waves eventually developing into TCs? Either way, a forecast track with intensity and wind radii could easily be developed during its life cycle." David Roth (B): "Mention that gales are present in Tropical Weather Outlooks or Special Tropical Disturbance Statements AND High Seas Forecasts. There MUST be gale warnings in the High Seas Forecasts for these systems, no ifs, ands, or buts. If not, then 'someone' has dropped the ball." Eric Blake (A or B): "Name usually if near land, otherwise Option B." Greg Holland (B): "Same comment for monsoon depressions, if they are loosely defined at the center. However, if they have tropical cyclone characteristics, then definition should be in Lagrangian terms (note that the cloud imagery and our interpretation thereof is Lagrangian). I do note that NHC requires a westerly wind at the surface to call these systems, so why change a system that ain't broke." James Franklin (B): "Issue gale warnings, and mention such in TWOs and STDSs. This is what we do now. I am very much opposed to calling a trough a tropical cyclone. Look, not all hazardous weather occurs in tropical cyclones. For the life of me, I cannot understand this desire to call anything hazardous in the tropics a tropical cyclone." Julian Heming (B): "I think we need to adhere to classical definitions of tropical cyclones (closed circulation), but also develop ways of warning on the hazards of such systems." Mark Lander (A): "Some of the TCs of 2003 (Claudette) showed that these systems can possess gales, and an impressive cloud system, and actually not have a distinct well-defined surface vortex. I think that if a persistent, well-organized cloud system (with some of the properties of a TC, such as an anticyclonic pattern to cirrus out- flow) should be named. This especially if there is a light wind region to the south of the gales (where only a small change in intensity or forward speed would result in the immediate formation of a surface vortex). I would bet that the statistics would show that persistent well-defined tropical disturbances that acquire gales become TCs most of the time, so there is an urgency to get out a tropical advisory at the earliest possible time." Phil Smith (C): "Could they be 'named tropical waves' drawing from the same pool of names as are used for regular TCs? They certainly present as much danger to shipping and island communities as named storms do, and may often have very high winds on the one side. Names are useful for alerting the general public and since these waves can easily become true TCs when they slow down a bit, I believe it would be a useful practice to help people know that the same disturbance being referred to as 'Tropical Wave Adam' has become 'Tropical Storm Adam'. And if 'Tropical Wave Adam' simply fizzles out without ever becoming 'Tropical Storm Adam', then no harm has been done and people have been warned of winds which are dangerous to their ships, homes, businesses or other interests." Ray Zehr (A): "I've never liked the criteria of 'closed circulation' for weak TCs. The criteria should be 'closed circulation in center relative coordinates'. I see nothing wrong with explaining to the public that a fast-moving vortex has strong winds on one side from the direction of motion, and that's it. I think in the Atlantic this occurs often with TDs and extratropical transitions, but rarely with TSs, however, it's apparently somewhat common off the west coast of Australia." Roger Edson (B): "However!!! The scatterometer and microwave imagery era has shown that it is wrong to assume that all do not have westerly winds to the south and a closed circulation. Those 'old' assumptions were based on lack of data and a bad use of terminology." Simon Clarke (C): "Call them 'Gale Force Tropical Waves'." Tony Cristaldi (C): "Mention that the only reason that the system does not have the westerly ground-relative winds needed to be designated as a TC is because of its fast forward speed." Analysis and Gary's Opinion --------------------------- First of all I'll say that Option D to Question #6 (ignore monsoon depressions and hope they'll go away) perhaps sounds facetious, but it was not meant as a joke. I've sometimes gotten the impression that they've often been handled that way in the past, particularly by JTWC, which has no provision in their operational plan (along with NHC) for a tropical depression which might have gale-force winds. That's not a problem for Australia and Fiji whose current definition of a tropical depression (tropical LOW in Australia) allows for gale-force winds if they are not occurring near the system's center. In the survey I voted for Option A (name as tropical storms), but I'll restrict that to include only systems for which the gales have begun to curve cyclonically around the circulation, even if at some distance from the center, and occupying from 1/3 to 1/2 or more of the circulation. Most systems at this stage are likely to continue evolving into a "classic" tropical cyclone anyway. I would not name systems with mainly a linear band of gales well-removed from the center and which often could exist without the presence of the LOW center. From my experience in following such depressions in the Australian Region and South Pacific, I have noted that sometimes the gales may be on the equatorward side due to a monsoonal westerly-wind burst; at other times on the poleward side due to a tight gradient with a subtropical HIGH. Following is a quote from an e-mail I received from Cliff Revell, who was (I think) formerly a member of New Zealand's Meteorological Service. This comes from a letter Cliff had sent to Steve Ready a few years earlier concerning the former WMO Region V requirement that a tropical depression must have gales surrounding the center in order to be classified as a tropical cyclone: "A suggestion. In order to maintain consistency with other regions, with past statistics, and to exclude those cases when gales occur at a distance from the centre in a more or less linear band caused by a strong anticyclone to the south, adopt the requirement that the envelope of gale-force or stronger winds be curved in a cyclonic sense." I must add, though, that Greg Holland and Ray Zehr have raised two concerns which should be considered. As Greg points out, gale-producing monsoon depressions can form over land in the northern portions of the Australian continent. As every tropical meteorological text written since the time of King Tut points out--tropical cyclones are absolutely a type of marine cyclone and always weaken when they move over land. Personally, I think it quite likely that most of these inland monsoon depressions have the band of gales to the north due to strong monsoonal westerlies and don't fit the cyclonic curvature criteria suggested by Cliff Revell. Ray Zehr (also Phil Smith) brought up the issue of multiple circu- lation centers. Most of my knowledge of monsoon depressions and gyres has come from Mark Lander, and from what Mark has related, monsoon gyres typically spawn multiple tropical cyclones, but the entire gyre itself only very rarely consolidates into a tropical cyclone (Typhoon Gladys of 1991 being an example). The smaller monsoon depression does often sport several convective clusters, some of which may exhibit rotation, but usually by the time an extensive area of gales has begun to curve around the larger center, that center has become dominant and the depression goes on to become a conventional tropical cyclone. With regard to rapidly translating tropical waves, it is interesting to note that while most persons in the tropical cyclone community tend to regard a westerly surface wind on the equatorward side an absolute requirement for the existence of a tropical cyclone, there are some prominent voices (again Ray and Greg) who would define a tropical cyclone in terms of center-relative coordinates. I voted for Option A (to name) on the survey, but this was somewhat of a turnaround from the way I'd previously thought on the issue. A couple of systems which helped to alter my way of thinking were Chantal (2001) and Claudette (2003). Chantal at one point was all but an open wave with 60-kt winds racing across the Caribbean. And Claudette was a very well-developed system with a very definite tropical storm appearance in satellite imagery with established anticyclonic outflow and 45-kt winds north of the "center", but (it was thought) without any westerly winds to the south. On 8 July a reconnaissance aircraft searched in vain for several hours for westerly winds and was about to depart the area when it very fortuitously discovered a 20-kt southwesterly wind and a very tiny vortex. So we then had an "instant" tropical storm. (I would add that I'm not in favor of naming strong tropical waves which exhibit very little if any vorticity and/or outflow, and which have substantial easterly winds on the equator- ward side. Such systems are not likely to develop quickly into tropical storms.) Somehow it seems a little inconsistent to issue a full advisory package (public advisory, forecast/advisory, discussion bulletin and strike probabilities) for a 25-kt tropical depression which may not be forecast to reach tropical storm intensity for 24-48 hours, but to simply relegate information on a gale or storm-force tropical wave to the TWOs and gale warnings buried down in the High Seas Forecasts. If they're not going to be named, then STDSs should be issued at least every six hours. Also, Roger Edson brings up a good point that even if a reconnaissance crew fails to find westerly winds, how do we know for sure they're not there? I can't speak for the general public in the Lesser Antilles or other Caribbean nations where these systems usually present a threat, but it is an unarguable point that among the U. S. general public, when a system is named, the interest jumps by an order of magnitude. And not just among the general public. Following is an excerpt from the report on Hurricane Claudette in the July, 2003, summary: The following quote from an e-mail written by Kenneth J. Schaudt of Marathon Oil Company illustrates how the attention of the public and other concerned parties spikes up when a tropical storm is named: "Much of the United States' natural gas is produced in the Gulf of Mexico. Since the threat of tropical storms may shut down production briefly, the market for natural gas responds to the perceived threats. On the 8th (of July) at 1806 UTC, the Special Tropical Disturbance Statement declaring Tropical Storm Claudette hit the wire. Within three minutes, the price of natural gas had jumped 10 cents." (Regarding the attention-grabbing power of a name, I know from several of my Australian correspondents that the same is true Down Under.) Regarding consistency with past practices, I think it is very likely that prior to the satellite era and the development of the Dvorak method of intensity analysis, and consequently a major emphasis being placed on organized central convection, many stronger monsoon depressions were classified as tropical storms in the areas of the world where they are prevalent, just as in the Atlantic in earlier years no doubt many of the "tropical" cyclones in the Best Track file were in reality subtropical systems. And I also think it highly probable that many of the short- lived Atlantic systems whose tracks are shown beginning just east of the Lesser Antilles and then disappearing in the central Caribbean were likely open tropical waves with gale-force or higher winds. Most of these were included in the Best Track file based on island reports of tropical storm winds, the assumption being that if sustained gale-force winds were present, then more than likely there was a surface circulation. So, to recap, I personally am in favor of "bending the rules" a little to name and treat as tropical storms systems which at a certain point in time may not have attained quite all the characteristics of "classic" tropical cyclones, but which can pose a significant threat to life and property and which likely will eventually evolve into "classic" tropical storms. There is nothing anomalous here--many systems have been named which were in truth much closer in nature to a subtropical storm than to a true tropical cyclone. It seems that this is the best way to help reduce confusion and achieve the ultimate goal of minimizing loss of life and mitigating damage. As Mark Lander has expounded many times, having the initial tropical cyclone advisory refer to a system near or exceeding hurricane intensity is not in the best interest of achieving this goal. ************************************************************************* ACTIVITY BY BASINS ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico Activity for July: 1 tropical depression Sources of Information ---------------------- Most of the information presented below was obtained from the various tropical cyclone products issued by the Tropical Prediction Center/National Hurricane Center (TPC/NHC) in Miami, Florida: discussions, public advisories, forecast/advisories, tropical weather outlooks, special tropical disturbance statements, etc. Some additional information may have been gleaned from the monthly summaries prepared by the hurricane specialists and available on TPC/NHC's website. All references to sustained winds imply a 1-minute averaging period unless otherwise noted. Atlantic Tropical Activity for July ----------------------------------- No tropical storms or hurricanes formed in the Atlantic basin during the month of July. This isn't anything out of the ordinary, as the annual average of named storms is about 4 every 5 years, with a hurricane developing about every third year. Over the past 25 years, July has been stormless in 13 years, or about half the time. The only intense July hurricane (Category 3 or higher on the Saffir/Simpson scale) since 1950 was Hurricane Bertha in 1996. Neither did any tropical depressions form during July until the final day of the month, when Tropical Depression 01 developed during the afternoon off the Georgia coast, becoming Tropical Storm Alex the next day. On 3 August Alex intensified into a Category 2 hurricane and passed very close to Cape Hatteras as it began to move northeastward away from the U. S. mainland. After weakening slightly on the 4th, Alex re-intensified on the 5th into a Category 3 hurricane as it scooted northeastward over the warm Gulf Stream waters south of the Canadian Maritimes. The report on Hurricane Alex will be included in the August summary. There were, however, a couple of weaker tropical disturbances worthy of mention. A small area of disturbed weather developed on the morning of 8 July about 240 nm southwest of Bermuda. During the afternoon a small surface LOW center formed and moved east-northeastward, passing very near Bermuda early on the 9th. According to Jack Beven, there was just enough of a wind and pressure perturbation at Bermuda to show that the circulation did exist at the surface. The lowest SLP recorded on the island was only 1019 mb. Convection associated with the LOW remained poorly-organized and the system soon encountered cooler SSTs after passing Bermuda. Disturbed weather developed off the east coast of Florida and extended northeastward from the Bahamas for several hundred miles late in the third week of July. This was associated with an upper-level LOW and a broad surface trough. A weak LOW formed on the 24th about 285 nm south- east of Cape Hatteras. By the morning of the 25th the LOW was centered about 150 nm east-southeast of Cape Hatteras, moving north-northwestward at about 12 kts with limited thunderstorm activity. During the early morning hours of 26 July convection increased significantly, the LOW then being located around 200 nm south of Long Island. Maximum winds were estimated to be 20-25 kts northeast of the center, and there was a possibility that if thunderstorm activity continued to increase near the center, a tropical or subtropical depression might develop. However, by midday the LOW was beginning to merge with a frontal zone, so tropical cyclone formation was no longer considered likely. ************************************************************************* NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180 Activity for July: 3 tropical depressions 1 tropical storm 1 hurricane 1 intense hurricane Sources of Information ---------------------- Most of the information presented below was obtained from the various tropical cyclone products issued by the Tropical Prediction Center/National Hurricane Center (TPC/NHC) in Miami, Florida (or the Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii, for locations west of longitude 140W): discussions, public advisories, forecast/advisories, tropical weather outlooks, special tropical disturbance statements, etc. Some additional information may have been gleaned from the monthly summaries prepared by the hurricane specialists and available on TPC/NHC's website. All references to sustained winds imply a 1-minute averaging period unless otherwise noted. Northeast Pacific Tropical Activity for July -------------------------------------------- Over the period 1971-2003, the Northeast Pacific basin's statistics for July are: 3.7 named storms, 2.0 hurricanes, and 1.1 intense hurri- cane. July of 2004 was pretty close to average with 3 named storms, 2 hurricanes, and 1 intense hurricane. Darby became the first Eastern Pacific intense hurricane since Kenna in October, 2002. All three of the storms formed well off the Mexican coast and moved generally west- northwestward with minimal effects on the coastline. Reports follow on these three storms--a special thanks to John Wallace for writing the summaries for Blas and Celia. In addition to the three named storms, there were also three tropical depressions for which advisories were issued. The first of these formed very early in the month well to the southwest of Cabo San Lucas on the southern tip of the Baja California Peninsula. Tropical Depression 02E formed around 1200 UTC on 2 July about 650 nm southwest of Cabo San Lucas and moved west-northwestward, dissipating by 03/1800 UTC about 850 nm west-southwest of the Cabo. Maximum winds were estimated at 25 kts. Also during the first week of July, Tropical Depression 01C formed in the Central North Pacific about 625 nm southeast of Johnston Island. The first advisory was issued by CPHC at 0300 UTC on 5 July, and the final one issued at 0300 UTC the next day when it became apparent the system was dissipating. Maximum winds in this depression were also estimated at only 25 kts. Finally, advisories were initiated on Tropical Depression 06E at 0900 UTC on 29 July with the center located about 415 nm south-southwest of Cabo San Lucas. However, the final advisory was issued only 18 hours later, locating the dissipating center about 215 nm west-southwest of its point of origin. In the case of TD-06E, the remnant LOW held together as it drifted west-southwestward across the expanse of the Eastern North Pacific. By late on 1 August convection had become re-established near the center of the LOW so advisories were begun again on the system at 02/0300 UTC. The center was placed roughly 1200 nm west-southwest of the southern tip of Baja California, and winds were estimated at 30 kts. The depression was located over warm SSTs and in a region of low shear, and intensification to near hurricane strength was initially forecast, but the system failed to respond to its apparently favorable environ- ment. Visible imagery on the 3rd and a 03/1440 UTC QuikScat overpass indicated that the depression no longer had a well-defined closed surface circulation and had degenerated into an elongated trough with embedded swirls and only a narrow band of weak convection. The final advisory at 03/2100 UTC placed the dissipating center about 1500 nm west-southwest of Cabo San Lucas. TROPICAL STORM BLAS (TC-03E) 12 - 15 July --------------------------------------- A. Storm Origins ---------------- Tropical Storm Blas formed from a tropical wave which had crossed Central America into the Eastern Pacific on 8 July. On 12 July an area of persistent disorganized convection that had been flaring up in the Eastern Pacific for several days had finally consolidated by midday, warranting its upgrade to Tropical Depression Three-E at 1500 UTC on 12 July when located approximately 300 nm south-southwest of Manzanillo, Mexico. The depression tracked steadily northwestward, under the influence of a ridge stationed over the United States Southwest. B. Synoptic History ------------------- The depression officially strengthened to Tropical Storm Blas at 0300 UTC on 13 July when centered about 265 nm southwest of Manzanillo. The nascent Blas had the distinction of being a very large storm, with storm-force wind radii that maxed out at 200 nm in the western quadrant on the 13th and into the 14th as it accelerated northwestward at the surprising speed of 17-18 kts. Blas reached its peak 1-min avg MSW of 50 kts, with a CP of 994 mb, at 0900 UTC on 13 July, an estimate which the NHC considered conservative. Blas began weakening on the 14th as it tracked into unfavorably cool waters. Its broad circulation remained robust--ship ELYS4 reported a 35-kt wind 100 nm from the center at 0600 UTC on the 14th, though the peak MSW overall was only 40 kts. Blas had dropped below storm strength by 2100 UTC that day and, as is typical of weakening NEP cyclones, decelerated and turned to the west-northwest along with the low-level trade winds. Its convection having completely collapsed, the last advisory was issued on Tropical Depression Blas at 0300 UTC on 15 July, the weakening center being located about 500 nm due west of Cabo San Lucas on the southern tip of the Baja California Peninsula. Not surprisingly, the large remnant vortex took some time to spin down, and was dimly evident in visible imagery as late as the 19th. C. Damage and Casualties ------------------------ Though squalls affected Baja California, no known casualties or damage were caused by Tropical Storm Blas. (Report written by John Wallace) HURRICANE CELIA (TC-04E) 19 - 25 July ----------------------------------- A. Storm Origins ---------------- As Tropical Storm Blas weakened and dissipated to the northwest, another tropical cyclone quickly formed in its wake. A vigorous tropical wave moved off the western coast of Africa on 5 July and tracked uneventfully across the Atlantic and Caribbean. The wave ultimately reached the Eastern Pacific, spawning a compact LOW which was evident as early as the 17th. As the system tracked roughly westward it became better organized and was upgraded to Tropical Depression Four-E at 0300 UTC on 19 July when centered approximately 550 nm south-southwest of Cabo San Lucas. B. Synoptic History ------------------- A ridge to the north steered TD-04E slowly to the west with slight oscillations. Its potential intensity was uncertain, due to the conflicting factors of nearby stable air but also low shear and warm SSTs. Even so, the depression strengthened to Tropical Storm Celia at 2100 UTC on 19 July when located about 600 nm south-southwest of Cabo San Lucas. Celia was as remarkably small as its predecessor Blas had been large: the gale-radius was only 60 nm, a value which varied little throughout the cyclone's lifetime--even at its peak--challenging "midget" status. Celia tracked uneventfully westward and steadily intensified, after a slight weakening late on the 20th and into the 21st due to interference from an upper-level LOW. However, it managed to avoid entraining nearby stable air into its circulation. Satellite detection of a mostly-closed eyewall warranted its upgrade to a hurricane at 0300 UTC on 22 July. The storm at this time had moved to a position about 750 nm southwest of Cabo San Lucas. Celia reached its peak MSW of 70 kts, with an estimated CP of 985 mb, six hours later at 22/0900 UTC. Celia weakened rapidly after its peak, probably due to both cooler water and entrained stable air, courtesy of an interfering upper-level LOW. By 2100 UTC on the 22nd the convection had largely collapsed, though the weakening trend stabilized near minimum tropical storm strength. Periodic deep convection and a good LLCC allowed it to hold on to storm status as it tracked westward. It seems that the entrainment of dry air decreased, shear remained low, and SSTs temporarily became a little warmer. On the 24th, however, Celia weakened to a depression, and turned toward the west-northwest with a slight increase in speed as it moved with the low-level flow. Convection remained remarkably tenacious for such a small cyclone, and the last warning was not issued until late on 25 July--at 2100 UTC--placing the weakening LLCC about 1375 nm west- southwest of the tip of Baja California. The remnant vortex remained evident in satellite imagery until late on the 27th, when it dissipated several hundred miles southeast of Hawaii. C. Damage and Casualties ------------------------ There were no known casualties or damage resulting from Celia. (Report written by John Wallace) HURRICANE DARBY (TC-05E) 26 July - 1 August -------------------------------------- A. Storm Origins ---------------- A tropical wave moved westward across the coast of Africa on 12 July and continued across the Atlantic and Caribbean, reaching the Eastern Pacific on 20 July. The system showed the first signs of organization on the 24th well to the south-southwest of Manzanillo, Mexico. The disturbance gradually became better organized and had developed into Tropical Depression 05E by 1800 UTC on 26 July when it was centered approximately 700 nm south-southwest of Cabo San Lucas on the southern tip of the Baja California Peninsula. Six hours later Dvorak classifications from SAB and TAFB had reached T2.5, so TD-05E was upgraded to Tropical Storm Darby. The circulation was still in its formative stages and had not completely separated from the ITCZ. B. Synoptic History ------------------- Tropical Storm Darby's convective structure became increasingly better organized during the 27th and by 1800 UTC the estimated MSW had reached 60 kts--just shy of hurricane status. There were some indications that a banding-type eye was trying to develop, but its appearance in satellite imagery was rather transient for the next 12 hours. However, SSM/I microwave data at 28/0336 and 28/0507 UTC clearly indicated that Darby had developed a 20-25 nm diameter eye embedded in a round CDO, and auto- mated ODT values were around 69 kts. Satellite CI estimates ranged from 55 to 77 kts, but taking all the evidence into consideration, Darby was upgraded to the season's second hurricane at 28/0900 UTC when located approximately 835 nm southwest of Cabo San Lucas. Darby at this time was moving west-northwestward at 11 kts around a subtropical ridge. Initially, the hurricane was forecast to peak at 80 kts and then begin to weaken as it encountered cooler SSTs. However, at 2100 UTC the cloud pattern had improved significantly and T-numbers had increased to 5.0, so the MSW was increased to 90 kts. A further surprise was in store. At 0600 UTC on 29 July Dvorak T-numbers from both TAFB and SAB had reached 6.0, or 115 kts. Darby had undergone rapid intensification over sub-27 C water with the MSW increasing from 35 kts to 105 kts in 54 hours. The MSW was set at 105 kts instead of 115 kts due to the fact that Darby was over 26 C water, and the forecaster felt that downward mixing of the strong winds was likely not occurring due to the cooler and more stable boundary layer. Nonetheless, Darby had become the first Category 3 or higher hurricane in the Eastern North Pacific since the very intense and destructive Hurricane Kenna in October, 2002. Darby's tenure as a major hurricane, however, was not to be for long. By 29/1500 UTC the eye was becoming less distinct and winds were dropped to 100 kts, and six hours later the eye was no longer visible and the MSW was further reduced to 90 kts. The demise of Hurricane Darby was rather quick as it moved over cooler SSTs and into increasing vertical shear. Only 24 hours after reaching its peak of 105 kts, Darby was only a minimal hurricane, and six hours later was a 55-kt tropical storm. Eastern North Pacific tropical cyclones have a higher "death rate" caused by systems moving over cold SSTs without encountering a baroclinic zone more so than in any other basin. Typically when systems moving north- westward or west-northwestward lose most of their deep convection and become shallow systems, they turn westward and move with the low-level trade winds. Darby was no exception to this as it began to track west- ward after crossing 130W. By 2100 UTC on 30 July Darby had been reduced to a swirl of low and mid-level clouds with isolated patches of deep convection to the north- east of the center. Satellite intensity estimates ranged from 35 to 65 kts, and a high resolution QuikScat overpass at 1446 UTC showed a 50-kt vector north of the center, so the intensity was set at 50 kts. However, the MSW was reduced to 40 kts six hours later, and at 1200 UTC on the 31st Darby was downgraded to a tropical depression. Darby had crossed 140W into the Central North Pacific by 0000 UTC on 1 August. Although the depression was moving over warmer water, it was running into strong southwesterly vertical shear. CPHC issued the final advisory on Darby at 01/0600 UTC, placing the dissipating center about 750 nm east of Hilo, Hawaii. The remnants of Darby continued westward, bringing rainfall totals of up to 150 mm in some parts of Hawaii. C. Damage and Casualties ------------------------ No reports of damage or casualties resulting from Hurricane Darby have been received. (Report written by Gary Padgett) ************************************************************************* NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180 Activity for July: 2 tropical storms ** 1 typhoon ** - one of these classified as a tropical storm only by China (NMCC) Sources of Information ---------------------- Most of the information presented below is based upon tropical cyclone warnings and significant tropical weather outlooks issued by the Joint Typhoon Warning Center of the U. S. Air Force and Navy (JTWC), located at Pearl Harbor, Hawaii. In the companion tropical cyclone tracks file, I normally annotate track coordinates from some of the various Asian warning centers when their center positions differ from JTWC's by usually 40-50 nm or more. All references to sustained winds imply a 1-minute averaging period unless otherwise noted. Michael V. Padua of Naga City in the Philippines, owner of the Typhoon 2000 website, normally sends me cyclone tracks based upon warnings issued by the Japanese Meteorological Agency (JMA) and the Philippines' Atmospheric, Geophysical & Astronomical Services Administration (PAGASA). Also, Huang Chunliang of Fuzhou City, China, sends data taken from synoptic observations around the Northwest Pacific basin. A very special thanks to Michael and Chunliang for the assistance they so reliably provide. In the title line for each storm I have referenced all the cyclone names/numbers I have available: JTWC's depression number, the JMA-assigned name (if any), JMA's tropical storm numeric designator, and PAGASA's name for systems forming in or passing through their area of warning responsibility. Northwest Pacific Tropical Activity for July -------------------------------------------- After a very active June with five typhoons churning Northwest Pacific waters, the month of July was rather quiet by comparison. Three tropical storms formed, with only one reaching typhoon status. Tropical Storm Kompasu/Julian formed just before mid-month and trekked westward, making landfall near Hong Kong as a minimal tropical storm. Late in the month Typhoon Namtheun formed roughly 500 nm northeast of Guam and a like distance to the southeast of Iwo Jima. Namtheun moved northwestward, then turned westward and moved south of Honshu toward a landfall on the island of Shikoku. The third storm was unnamed, being classified as a tropical storm by only NMCC and the Guangdong Regional Meteorological Centre (GRMC). All the other warning agencies treated this system as only a tropical depression or low-pressure area, but wind observations recorded at several stations in southeastern China strongly suggest that this system was a tropical storm. A report on this system, compiled and sent by Huang Chunliang of Fuzhou City, follows. Reports on the other two named cyclones also follow, the one on Kompasu authored by Kevin Boyle. A special thanks to Kevin and Chunliang for their assistance. ADDENDA TO JUNE TROPICAL CYCLONE TRACKS For the past several months Huang Chunliang has been preparing and sending tables summarizing the MSW estimations from the various TCWCs. Chunliang was away at Shanghai for job-related training for most of the months of July and August and was not able to complete the MSW tables for the June typhoons. Following are the tables he recently sent for Typhoon Mindulle and Typhoon Tingting. ========================================================= == Typhoon 10W/MINDULLE/0407/IGME (Jun 21-Jul 4, 2004) == ========================================================= TCWC Storm ID PEAK MSW (kt) -------------------------------------------------------------- JTWC Typhoon 10W (MINDULLE) 125 JMA Very Severe Typhoon 0407 (MINDULLE) 90 PAGASA Typhoon IGME 105 NMCC Typhoon 0407 (MINDULLE) 100 HKO Typhoon MINDULLE (0407) 90 CWB Moderate Typhoon 0407 (MINDULLE) 90 ==================================================== == Typhoon 11W/TINGTING/0408 (Jun 24-Jul 4, 2004) == ==================================================== TCWC Storm ID PEAK MSW (kt) -------------------------------------------------------------- JTWC Typhoon 11W (TINGTING) 80 JMA Very Severe Typhoon 0408 (TINGTING) 85 NMCC Typhoon 0408 (TINGTING) 80 HKO Typhoon TINGTING (0408) --* CWB Moderate Typhoon 0408 (TINGTING) --# Note 1 (*): HKO never issued any real-time warnings on this typhoon, which remained outside their AOR throughout its life. Note 2 (#): CWB data was insufficient for me when I was away in Shanghai. TROPICAL STORM KOMPASU (TC-12W / TS 0409 / JULIAN) 13 - 16 July ----------------------------------------------- Kompasu: contributed by Japan, is the compass, a v-shaped device for describing circles or arcs; also the name of the constellation Circinus A. Storm Origins ---------------- At 0600 UTC on 12 July a weak, cycling area of deep convection was first mentioned in JTWC's STWO and located approximately 500 nm southeast of Okinawa. Animated multi-spectral imagery revealed a possible weak LLCC associated with this system. An upper-level analysis indicated that the disturbance was within an area of weak shear and weak diffluence aloft. The potential for development into a significant tropical cyclone at this point was assessed as poor. This was upgraded to fair status in a re-issued advisory at 12/1930 UTC. A TCFA was issued at 13/0230 UTC after the system had become better organized. The LLCC was well-developed at this time, but exposed as seen in multi-spectral imagery. A QuikScat pass also showed a well- developed tight vortex with the associated deep convection propagating toward the southern end of an analyzed shear line. The first warning on Tropical Depression 12W was issued at 13/0600 UTC with the centre located 340 nm south-southeast of Okinawa and moving toward the west at 8 kts. Even though this system was exiting an area of high vertical shear, the dynamical aids did not indicate any further development nor did they initialize the storm very well. Pint-sized TD-12W spent the rest of the day tracking westward and accelerating, its forward speed reaching 17 kts by 1800 UTC. The baby tropical cyclone was christened Kompasu following JMA's upgrade to tropical storm intensity at 0000 UTC on the 14th. (PAGASA named the depression Julian at 13/1200 UTC when it entered that agency's AOR.) B. Synoptic History ------------------- JTWC upgraded Kompasu to a tropical storm at 14/0600 UTC when the system was located 180 nm east-southeast of Kaoshiung, Taiwan. Kompasu was still moving briskly toward the west or west-northwest under the influence of a mid-level steering ridge to the northeast. The system continued to exhibit an exposed LLCC due to continued shearing from the east. However, a little strengthening had been occurring and the MSW reached 40 kts at 14/1200 UTC. At this time Kompasu unexpectedly turned west-southwestwards, and this heading ensured that the centre would pass south of Taiwan. Tropical Storm Kompasu/Julian did not change a great deal during the 15th. A peak intensity of 45 kts had been reached at 14/1800 UTC and this intensity was maintained throughout the following day. The radius of gale-force winds fluctuated in succeeding JTWC warnings, but to give the reader some idea of Kompasu's minute size, 34-kt wind radius never exceeded 50 nm during the maximum intensity. An interesting possibility is that a tropical cyclone, similar to Kompasu, might have escaped unnoticed in the pre-satellite era, especially one which did not make landfall near a population centre like Hong Kong. At 0000 UTC on 16 July Tropical Storm Kompasu was 85 nm southeast of Hong Kong and moving west-northwestward at 10 kts. The system shifted to a more poleward track and came ashore near Hong Kong at approximately 16/0900 UTC. Kompasu was barely at tropical storm intensity by the time it made landfall. The LLCC proceeded northward, leaving behind the upper-level circulation which was being sheared toward the southwest. The final warning was issued by JTWC at 16/1200 UTC when the centre was continuing northward 40 nm east of Hong Kong. JMA continued to monitor Kompasu as a tropical depression for another six hours before that agency also dissipated the storm. C. Meteorological Observations ------------------------------ Waglan Island reported a 10-min sustained MSW of up to 65 kts at 16/0900-1000 UTC. The lowest pressure of 996 mb was recorded between 0500-0600 UTC. (The AWS at Waglan Island sits more than 75 m above MSL.) The following report was sent by Huang Chunliang. According to the HKO warnings, Tropical Storm Kompasu (0409) made landfall over Sai Kung at around 16/0700 UTC, when it was about 25 km to the east of Hong Kong Observatory Headquarters, its closest approach, with a MSW of 40 kts and a CP of 990 hPa. The HKO report on TS Kompasu can be found at the following link: In Guangdong Province, the coastal region near the mouth of Pearl River reported sustainded winds of Beaufort Force 7 to 8, gusting to Force 9 to 10 during the storm. Pingshan & Longqi, both located in Shenzhen City, recorded peak gusts to 50.5 kts, while the Gulf of Daya (Huizhou City) & Guishan (Zhuhai City) both reported gusts topping 46.7 kts. D. Damage and Casualties ------------------------ News reports indicated that Tropical Storm Kompasu only caused minor damage in Hong Kong. Three people were injured as a result of wind- borne debris. However, many transportation services were either cancelled or ran on reduced schedules, and the stock market, banks and other institutions were closed. Emergency shelters were opened for the homeless. E. Addendum to July Tropical Cyclone Tracks File ------------------------------------------------ Following is the MSW comparison table prepared and sent by Huang Chunliang. This was unavailable at the time the July tracks file was sent. ============================================================== == Tropical Storm 12W/KOMPASU/0409/JULIAN (Jul 11-16, 2004) == ============================================================== TCWC Storm ID PEAK MSW (kt) -------------------------------------------------------------- JTWC Tropical Storm 12W (KOMPASU) 45 JMA Typhoon 0409 (KOMPASU) 45 PAGASA Tropical Storm JULIAN 40* NMCC Tropical Storm 0409 (KOMPASU) 45 HKO Tropical Storm KOMPASU (0409) 45 CWB Weak Typhoon 0409 (KOMPASU) 40 Note (*): The MSW is merely the "peak" value based on the limited warnings released only when the storm was travelling within the restricted AOR, so it may have not been the real peak. (Report written by Kevin Boyle with contributions by Huang Chunliang.) TYPHOON NAMTHEUN (TC-13W / TY 0410) 24 July - 1 August -------------------------------------- Namtheun: contributed by Laos, is the name of a river--one of the tributaries of the Mekong River A. Storm Origins ---------------- The origins of July's only typhoon lay in an area of convection which formed on 23 July about 470 nm northeast of Guam and was persistent. Animated multi-spectral and water vapor imagery revealed upper-level divergence into an upper-level LOW east of a possible LLCC. A QuikScat pass depicted a very weak circulation embedded in an elongated area of broad troughing, and an upper-level analysis suggested an environment of low vertical shear and fair divergence. At 24/0600 UTC the system was relocated two degrees poleward to a point approximately 540 nm northeast of Guam. The potential for development was upped to fair at 24/1100 UTC as deep convection was increasing over the LLCC. A recent QuikScat pass indicated stronger winds in the northeast quadrant, but the core of the circulation remained weak. An upper-level analysis indicated that anticyclonic flow was centered over the LLCC with good outflow in the equatorward direction. B. Synoptic History ------------------- JMA classified the system as a 30-kt tropical depression at 24/1200 UTC, and JTWC issued a TCFA at 24/1400 UTC. The area of convection was quasi-stationary approximately 530 nm northeast of Guam, and satellite imagery indicated that deep convection was continuing to increase over the LLCC, even though a recent QuikScat pass showed that the LLCC was still very disorganized and not co-located with the mid-level rotation. JTWC's first warning on Tropical Depression 13W was issued at 0000 UTC on 25 July. The center was located about 550 nm east-southeast of Iwo Jima and was drifting north-northwestward at 2 kts. A mid-level steering ridge to the northeast was forecast to continue guiding the tropical cyclone to the north-northwest. At 25/1200 UTC both JTWC and JMA upgraded the depression to tropical storm status with the latter agency assigning the name Namtheun. Satellite CI estimates were 35 and 55 kts, but a 25/0409 UTC CIMSS AMSU intensity estimation product showed the system to be near 992 mb, and recent 85-GHz SSM/I passes revealed a possible mid-level eye forming. The MSW was set at 50 kts in JTWC's warning and at 40 kts (10-min avg) in JMA's warning. By 1800 UTC Tropical Storm Namtheun was passing approximately 400 nm east of Iwo Jima, still tracking northwestward. The 26th of July was a day of rapid intensification for Namtheun. JTWC upgraded the system to a 65-kt typhoon at 26/0000 UTC when it was centered about 370 nm east of Iwo Jima. The MSW was bumped up to 90 kts at 0600 UTC based on CI estimates of 77 and 102 kts. A 26/0328 UTC AMSR-E pass revealed a 15-nm eye surrounded by a well-defined banding feature. At the same time JMA increased the intensity (10-min avg) from 55 kts to 80 kts. By 1800 UTC winds had increased to an estimated 115 kts with the typhoon located approximately 300 nm east-northeast of Iwo Jima. This, however, proved to be Namtheun's peak intensity. (JMA's peak 10-min avg MSW was 85 kts with an attendant CP of 945 mb.) At its peak intensity Namtheun was a rather small typhoon with gales covering an area about 200 nm in diameter. The radius of typhoon-force winds was estimated at 30 nm. Typhoon Namtheun continued tracking steadily northwestward on the 27th as it slowly began to weaken. The eye was no longer evident in EIR imagery by 1200 UTC and the MSW was brought down to 105 kts, and at 1800 UTC the intensity was reduced further to 90 kts. Namtheun was then centered about 360 nm southeast of Tokyo and moving northwestward at 10 kts. On 28 July Namtheun's track changed to more of a west- northwesterly heading. The storm held its 90-kt intensity until 1200 UTC when it was lowered to 80 kts. By 0000 UTC on 29 July Namtheun was moving due westward at around 4 kts as it passed a little over 200 nm due south of Tokyo, and this westerly motion continued throughout the day. The MSW remained pegged at 80 kts until 29/1800 UTC when it was decreased slightly to 75 kts. A 29/1143 UTC SSM/I pass in the 37-GHz band revealed a ragged, 50-nm diameter eye. Animated water vapor imagery showed that deep convection in the northwest quadrant was decreasing as the system encountered northerly flow aloft and drier low-level inflow from Japan. Typhoon Namtheun continued to move generally westward south of Japan on the 30th. At 1200 UTC the cyclone was centered approximately 280 nm southwest of Tokyo. JTWC reduced the MSW to 65 kts, based on CI esti- mates ranging from 55 to 77 kts plus a UW-CIMSS CP estimate of 975 mb, which would correspond to a MSW of around 66 kts. Drier air from Japan had continued to erode the convection in the western semicircle of the storm with deep convection now restricted to the eastern quadrants. JTWC downgraded Namtheun to tropical storm status at 30/1800 UTC with CI estimates still ranging from 55 to 77 kts. Interestingly, JMA main- tained Namtheun as a typhoon for another 18 hours after JTWC's downgrade. The storm's heading became increasingly northwesterly on 31 July as it tracked around the southwestern periphery of the steering ridge east of Japan. At 31/0600 UTC Namtheun was centered approximately 80 nm east- southeast of Iwakuni, Japan, moving northwestward at 11 kts. JTWC's peak MSW was 55 kts, but JMA was still treating Namtheun as a minimal typhoon. By 1200 UTC the center had moved inland over the Japanese island of Shikoku, and by 1800 UTC had crossed western Honshu and emerged into the Sea of Japan. At 0000 UTC on 1 August Namtheun's center was in the Sea of Japan about 105 nm east of Busan, South Korea, tracking slowly northwestward. Winds were down to 35 kts as a result of terrain-induced weakening; also, the LLCC was lagging behind the upper-level circulation due to increased shear. At 01/0600 UTC the cyclone was moving slowly northward east of South Korea. Satellite CI estimates ranged from 25 to 35 kts, but JTWC deemed the system to be extratropical and issued their final warning. JMA carried Namtheun through one more warning cycle, then downgraded the system to a depression and issued their final warning at 1200 UTC. C. Meteorological Observations ------------------------------ Karl Hoarau sent me some hourly observations from the station at Murotomisaki (WMO 47899). The eye of Typhoon Namtheun passed 18 nm to the south of the station around 0200 UTC on 31 July. The storm had already been downgraded by JTWC but was still being carried as a typhoon by JMA. The following pressures have been reduced to sea level, and the winds represent 10-min mean winds. 30 July at 2100 UTC 991.2 mb 51 kts 2200 UTC 989.7 mb 70 kts 2300 UTC 988.4 mb 72 kts 31 July at 0000 UTC 986.8 mb 77 kts 0100 UTC 984.9 mb 87 kts 0200 UTC 984.2 mb 91 kts 0300 UTC 985.6 mb 76 kts 0400 UTC 989.6 mb 68 kts 0500 UTC 992.3 mb 53 kts One fact which should be kept in mind is that the Murotomisaki station is located on a cape at an elevation of 185 metres. (A special thanks to Karl for sending these observations.) D. Damage and Casualties ------------------------ I have received no reports of damage of casualties resulting from Typhoon Namtheun. E. Additional Observations -------------------------- At the last minute I received a report from Huang Chunliang of observations from Japanese stations. I have included the report essentially just as he sent it. A special thanks to Chunliang for sending the data. NOTE: To convert metres/second (m/s) to knots approximately, just double the m/s: e.g., 35 m/s ~= 70 kts. To convert precisely, divide m/s by 0.51444: e.g., 35 m/s = 68 kts. {Part I}. Landfalls (base on the JMA warnings) ============================================== 1. Severe Typhoon 0410 (NAMTHEUN) made landfall in western Kochi Prefecture around 31/0700 UTC with a MSW of 35 m/s and a CP of 980 hPa. 2. Typhoon 0410 (NAMTHEUN) made landfall near Hiroshima City, Hiroshima Prefecture around 31/1230Z with a MSW of 23 m/s and a CP of 992 hPa. {Part II}. Top-5 storm totals [29/1500-02/1500Z] ================================================ Ranking Prefecture Station Rainfall (mm) ------------------------------------------------------------- 01 Tokushima Asahimaru 1243 02 Nara Mt.Hidegatake 1153 03 Tokushima Kitou 980 04 Tokushima Fukuharaasahi 936 05 Kochi Shigetou 772 {Part III}. Top-5 daily rainfall obs ==================================== Ranking Prefecture Station Rainfall (mm) ---------------------------------------------------------------------- 01 Tokushima Asahimaru 588*[31/1500-01/1500Z] 02 Nara Mt.Hidegatake 588 [30/1500-31/1500Z] 03 Tokushima Fukuharaasahi 516 [30/1500-31/1500Z] 04 Kochi Yanase 514 [30/1500-31/1500Z] 05 Tokushima Kitou 512*[31/1500-01/1500Z] {Part IV}. Top-5 hourly rainfall obs ==================================== Ranking Prefecture Station Rainfall (mm) ---------------------------------------------------------------------- 01 Kochi Nakamura 117*[01/1540-01/1640Z] 02 Kochi Shigetou 110*[01/0000-01/0100Z] 03 Ehime Chikanaga 104*[01/1410-01/1510Z] 04 Kochi Motoyama 92 [01/0910-01/1010Z] 05 Kochi Kubokawa 91*[01/1140-01/1240Z] {Part V}. Top-5 peak sustained wind (10-min avg) obs ==================================================== Ranking Station Peak wind (mps/dir) ------------------------------------------------------------------------- 01 Murotomisaki, Kochi (WMO47899, Alt 185m) 47.7/E [31/0210Z] 02 Hiwasa, Tokushima (JMA71266, Alt 3m) 22 /E [31/0310Z] 03 Shionomisaki, Wakayama (WMO47778, Alt 73m) 19.0/E [30/1810Z] 04 Tsu, Mie (WMO47651, Alt 3m) 18.1/ESE [31/0320Z] 05 Tamano, Okayama (JMA66501, Alt 2m) 18 /E [31/1250Z] {Part VI}. Top-5 peak gust obs ============================== Ranking Station Peak wind (mps/dir) ------------------------------------------------------------------------- 01 Murotomisaki, Kochi (WMO47899, Alt 185m) 60.9/ENE [31/0200Z] 02 Hachijojima, Tokyo (WMO47678, Alt 79m) 44.6/ENE [29/0703Z] 03 Shionomisaki, Wakayama (WMO47778, Alt 73m) 37.8/ENE [30/0812Z] 04 Owase, Mie (WMO47663, Alt 15m) 36.8/E [30/2344Z] 05 Kure, Hiroshima (WMO47766, Alt 4m) 31.1/NNE [31/0902Z] {Part VII}. Top-5 SLP obs ========================= Ranking Station Min SLP (hPa) ---------------------------------------------------------------- 01 Murotomisaki, Kochi (WMO47899) 983.3 [31/0237Z] 02 Shimizu, Kochi (WMO47898) 989.2 [31/0555Z] 03 Sukumo, Kochi (WMO47897) 989.9 [31/0647Z] 04 Matsuyama, Ehime (WMO47887) 990.3 [31/0948Z] 05 Kochi, Kochi (WMO47893) 990.5 [31/0431Z] {Part VIII} References (Japanese versions only) =============================================== NOTE: "*" = record-breaking values for relevant stations. F. Addendum to July Tropical Cyclone Tracks File ------------------------------------------------ Following is the MSW comparison table prepared and sent by Huang Chunliang. This was unavailable at the time the July tracks file was sent. ==================================================== == Typhoon 13W/NAMTHEUN/0410 (JuL 24-Aug 3, 2004) == ==================================================== TCWC Storm ID PEAK MSW (kt) -------------------------------------------------------------- JTWC Typhoon 13W (NAMTHEUN) 115 JMA Very Severe Typhoon 0410 (NAMTHEUN) 85 NMCC Typhoon 0410 (NAMTHEUN) 100 HKO Typhoon NAMTHEUN (0410) ---* CWB Moderate Typhoon 0410 (NAMTHEUN) ---# Note 1 (*): HKO never issued any real-time warnings on this typhoon, which remained outside their AOR throughout its life. Note 2 (#): CWB data was insufficient for me when I was away in Shanghai. (Sections A-D written by Gary Padgett; Sections E & F compiled by Huang Chunliang) TROPICAL STORM (NMCC 0411 / NRL Invest 94W) 26 - 27 July ------------------------------------------------ A. Introduction --------------- Only NMC and GRMC, both sub-agencies of CMA (China Meteorological Administration), classified the system as a tropical storm in real time, while HKO, JMA, TMD and SMG (Macao) ranked it as a tropical depression only. Another three TCWCs: JTWC, CWB and PAGASA, however, just treated 94W as a tropical disturbance/low-pressure area. It should be noted that the last time there was a NMC tropical storm without a JMA number (i.e., JMA never regarded it as a tropical storm) was in mid-December, 1999, when NMC issued several warnings on a SCS tropical storm (numbered TS-9917 by NMC and TD-33W by JTWC). B. Synoptic History ------------------- Both NMC and GRMC initiated warnings on TD-03 at 26/0600 UTC. And the MSW of 30 kts was kept for three warning cycles before two ships reported winds of gale force in the wee hours on the 27th (locally). So the depression was upgraded to Tropical Storm 0411 at 27/0000 UTC. It took only three hours for the unnamed storm, which turned out to be a short fuse, to make landfall. According to the NMC and GRMC warnings, Tropical Storm 0411 made landfall in the coastal region between Huilai County and Lufeng City, Guangdong Province around 27/0305 UTC with a MSW of 40 kts and a CP of 995 hPa. Once inland, the storm began to fade rapidly. The cyclone was downgraded to a 25-kt depression at 27/0600 UTC, at which time China issued their final warning. C. Meteorological Observations ------------------------------ (1) Wind Observations --------------------- The majority of the counties/cities of coastal southeastern Guangdong: Jieyang, Shantou and Shanwei Cities, as well as some counties/cities of Chaozhou City, reported sustained winds of Beaufort Force 6 to 8, gusting to Force 9 to 10 during the storm. Significant gust reports included: Station Jiadong, Lufeng City (a sub-city of Shanwei City) - 52.7 kts Huilai Chuanqiao Reservoir (Huilai County, Jieyang City) - 49.2 kts (2) Rainfall Observations ------------------------- (a) Guangdong Province ---------------------- [27/0000-28/0000 UTC]: Rains >50 mm were recorded in 33 counties/cities, among which, Heping County, Fengshun County, Wengyuan County, Chaozhou City, Lianping County, Chao'an County, Shantou City and Chaoyang City reported rains >100 mm with Qingzhou, Heping County reporting the highest amount of 170.2 mm. [28/0000-29/0000 UTC]: Rains >50 mm were recorded in 29 counties/cities, among which, Shanwei City, Sihui City, Zhongshan City, Fengkai County, Raoping County and Zhuhai City reported rains >100 mm with Nanlang, Zhongshan City reporting the highest amount of 182.6 mm. [29/0000-30/0000 UTC]: Rains >50 mm were recorded in 28 counties/cities, among which, Huilai County, Maoming City, Puning City, Suixi County reported rains >100 mm with Maoming City reporting the highest amount of 112.5 mm. (b) Fujian Province ------------------- [27/0000-29/0000 UTC]: 3 stations (Yunxiao, Zhaoan & Dongshan) located in southern Fujian recorded rains >100 mm with Yunxiao County, Zhangzhou City reporting the highest amount of 116.6 mm. (c) Artificial Rain ------------------- Artificial rainfall missions were selectively carried out in a few regions of both Guangdong and Fujian Provinces, where drought was relaxed to some extent thanks to the rains, whether artificial or not. D. Damage and Casualties ------------------------ In Nan'ao County, Shantou City, 11 fishermen were confirmed dead and another 11 were reported missing and feared dead after a fishing vessel capsized near Guangdong's Nanpeng Dao around the noon of July 27 (locally). In Huilai County, Jieyang City, another fishing boat was bowled over by the stormy waves, leaving two fishermen missing in the evening of July 27 (locally). In Chao'an County, Chaozhou City, one person was killed when a tornado hit the county's Fengtang and Fuyang Towns around 27/1100 (BJT). Another seven residents were injured when more than 100 houses in four villages were damaged or destroyed. Preliminary statistics indicated that a total of 409 people from 93 families sustained damaged with 24 families home- less. Direct economic losses were estimated at 11.2 million yuan. Damage to coastal dikes, water conservation facilities and farmlands was also reported in the Province. E. Addendum to July Tropical Cyclone Tracks File ------------------------------------------------ Following is the MSW comparison table prepared and sent by Huang Chunliang. This was unavailable at the time the July tracks file was sent. ==================================================== == Tropical Storm 94W/0411/TD03 (Jul 26-27, 2004) == ==================================================== TCWC Storm ID PEAK MSW (kt) -------------------------------------------------------------- JMA Tropical Depression 30 NMCC Tropical Storm 0411/TD03* 45 HKO Tropical Depression 30 TMD Tropical Depression 30 Note 1: In the title line the storm grade was adopted based on the classification of the most "radical" TCWC. Also, all the storm names/ numbers available to me have been referenced. In addition, the starting date points to the one when the system was initially upgraded to TD status by whatever TCWC, while the ending date represents the one when the storm was finally ranked as a TD by whatever TCWC. (In this regard, NMCC was the TCWC that took the lead in upgrading the system to TD status on the 26th, while all the four agencies above issued their final TC bulletins at 27/0600 UTC.) Note 2 (*): The system was numbered "TD03" at 26/0600 UTC, when NMCC initiated their TC warnings. Note 3: Only NMC and GRMC, both sub-agencies of CMA (China Meteorological Administration), classified the system as a tropical storm in real time, while HKO, JMA, TMD and SMG (Macao) ranked it as a tropical depression only. Another three TCWCs, JTWC, CWB & PAGASA, however, just treated 94W as a tropical disturbance/low-pressure Area. (Report written by Huang Chunliang with slight editing by Gary Padgett) ************************************************************************* NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea Activity for July: No tropical cyclones ************************************************************************* SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E Activity for July: No tropical cyclones ************************************************************************* NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E Activity for July: No tropical cyclones ************************************************************************* NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E Activity for July: No tropical cyclones ************************************************************************* SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E Activity for July: No tropical cyclones ************************************************************************* EXTRA FEATURE In order to shorten the amount of typing in preparing the narrative material, I have been in the habit of freely using abbreviations and acronyms. I have tried to define most of these with the first usage in a given summary, but I may have missed one now and then. Most of these are probably understood by a majority of readers but perhaps a few aren't clear to some. To remedy this I developed a Glossary of Abbreviations and Acronyms which I first included in the July, 1998 summary. I don't normally include the Glossary in most months in order to help keep them from being too long. If anyone would like to receive a copy of the Glossary, please e-mail me and I'll be happy to send them a copy. ************************************************************************* AUTHOR'S NOTE: This summary should be considered a very preliminary overview of the tropical cyclones that occur in each month. The cyclone tracks (provided separately) will generally be based upon operational warnings issued by the various tropical cyclone warning centers. The information contained therein may differ somewhat from the tracking and intensity information obtained from a "best-track" file which is based on a detailed post-seasonal analysis of all available data. Information on where to find official "best-track" files from the various warning centers will be passed along from time to time. The track files are not being sent via e-mail. They can be retrieved from the archive sites listed below. (Note: I do have a limited e-mail distribution list for the track files. If anyone wishes to receive these via e-mail, please send me a message.) Both the summaries and the track files are standard text files created in DOS editor. Download to disk and use a viewer such as Notepad or DOS editor to view the files. The first summary in this series covered the month of October, 1997. Back issues can be obtained from the following websites (courtesy of Michael Bath, Michael V. Padua, Michael Pitt, and Chris Landsea): Another website where much information about tropical cyclones may be found is the website for the UK Meteorological Office. Their site contains a lot of statistical information about tropical cyclones globally on a monthly basis. The URL is: TROPICAL CYCLONE REPORTS AVAILABLE JTWC now has available on its website the complete Annual Tropical Cyclone Report (ATCR) for 2003 (2002-2003 season for the Southern Hemisphere). ATCRs for earlier years are available also. The URL is: Also, TPC/NHC has available on its webpage nice "technicolor" tracking charts for the 2003 Atlantic and Eastern North Pacific tropical cyclones; also, storm reports for all the 2003 Atlantic and Eastern North Pacific cyclones are now available, as well as track charts and reports on storms from earlier years. The URL is: A special thanks to Michael Bath of McLeans Ridges, New South Wales, Australia, for assisting me with proofreading the summaries. PREPARED BY Gary Padgett E-mail: garyp@alaweb.com Phone: 334-222-5327 Kevin Boyle (Eastern Atlantic, Western Northwest Pacific, South China Sea) E-mail: newchapelobservatory@btinternet.com John Wallace (Assistance with Eastern North Pacific) E-mail: dosidicus@aol.com Huang Chunliang (Assistance with Western Northwest Pacific, South China Sea) E-mail: huangchunliang@hotmail.com Simon Clarke (Northeast Australia/Coral Sea, South Pacific) E-mail: saclarke@iprimus.com.au ************************************************************************* ************************************************************************* Uploaded: 09.11.04 / Typhoon2000.ph, Typhoon2000.com