3. Super Typhoon SUDAL (Cosme/03w)       Print this Article
>> April 03-18, 2004

Sudal: contributed by South Korea, is the name for the otter - a small river animal with thick brown fur, four webbed feet and a flat tail.

Storm Origins

At 0600 UTC on 28 March JTWC began issuing STWOs on a persistent area of convection approximately 290 nm southeast of Pohnpei. The potential for development was considered poor, and initial prospects for strengthening were not good in the high shear environment. However, the next day shearing conditions eased and multi-spectral satellite imagery depicted cycling deep convection associated with a broad LLCC. The development potential remained poor for several days. Following a relocation of the system's centre to a position 100 nm east-southeast of Chuuk at 0000 UTC on 2 April, the disturbance was finally upgraded to a fair potential for development. Multi-spectral satellite animations revealed deep convection and low-level inflow associated with the LLCC while surface pressures on the island of Chuuk were falling steadily (3 mb per 24 hours). A TCFA was issued at 02/0300 UTC with the environment now much more conducive for development. Despite this, the disturbance was slow to develop and did not achieve tropical depression status until 04/0000 UTC, when the first warning was issued.

Storm History

At 0000 UTC on 4 April Tropical Depression 03W was located 100 nm west-southwest of Chuuk and moving slowly west at 4 kts. Although the centre was partially-exposed, increased deep convection soon filled the LLCC, and after further intensification TD-03W was upgraded to a tropical storm with 35-kt winds. Continued strengthening brought the MSW up to 55 kts at 05/0600 UTC, and following JMA's upgrade to tropical storm intensity, the system was named Sudal--the first named tropical cyclone of 2004 in the Northwest Pacific basin. At this point Tropical Storm Sudal was moving toward the north, but this heading proved to be a temporary phase as a building mid-latitude ridge soon shifted the track back toward the west by 06/0000 UTC.

At 06/0000 UTC Sudal was nearing typhoon intensity approximately 260 nm south-southeast of Guam. Six hours later, the MSW was raised to 70 kts, resulting in an upgrade to typhoon status. At this time, enhanced infrared satellite imagery suggested that a cloud-filled eye could be forming. The 06/0600 UTC and 06/1200 UTC positions were each shifted about 30 nm to the north in order to reflect data from a 06/0818 UTC QuikScat pass and Guam radar. Typhoon Sudal continued westward and passed approximately 180 nm south of Guam at 06/1800 UTC with the island community remaining outside the radius of gale-force winds.

Typhoon Sudal had intensified to 80 kts by 0000 UTC on 7 April as it tracked west-northwestward roughly 200 nm south of Guam. A 07/1014 UTC microwave pass revealed a distinct eye, although it was still cloud- covered in infrared pictures. The storm turned to a west-southwesterly track as a mid-level ridge built to the northwest of the system.

Continuing west-southwestward at 9 kts, Sudal became a major typhoon (>=100 kts) at 0000 UTC on 8 April when it was centred approximately 125 nm east of Yap. The island at this time lay inside the radius of gale-force winds and conditions steadily worsened as the typhoon approached. By 1800 UTC Sudal was bearing down on Yap with the MSW nudging up to 110 kts. To make matters worse, the forward motion of Sudal was slowing as it threatened to make a transition to a more poleward track. Also, the upper-level environment was still favourable for further intensification.

The island of Yap was located a mere 25 nm north of the eye at 09/0000 UTC and was being given a real walloping within Sudal's inner eyewall. The lowest SLP recorded on the island was 958.5 mb at 0050 UTC on 9 April. Sudal subsequently began to move slowly away from Yap on a west-northwesterly to northwesterly heading, accelerating to around 8 or 9 kts. Strengthening had resumed and by the end of the 9 April the MSW had risen to 125 kts.

A 09/2224 UTC AMSU image depicted concentric eyewalls, indicating that Sudal had reached super typhoon intensity (>=130 kts) at 10/0000 UTC while centred approximately 190 nm west-northwest of Yap. This was to be the peak intensity, and subsequent satellite imagery revealed that weakening had begun--the eye had become partially cloud-filled as seen in enhanced infrared and multi-spectral imagery. Despite this, the maximum intensity of 130 kts was maintained throughout the 10th and into the 11th.

(Editor's Note: The peak 10-min avg MSW and minimum CP assigned by JMA were 85 kts and 940 mb, respectively. NMCC and PAGASA each estimated the peak intensity at 100 kts, while the CWB of Taiwan's maximum MSW was 85 kts--the same as Japan's. HKO estimated Sudal's peak intensity at 95 kts, but did not issue any real-time warnings as the cyclone remained outside that agency's AOR.)

By 0000 UTC on 11 April Super Typhoon Sudal had moved well away from Yap, being located 410 nm to the west-northwest. Enhanced infrared satellite pictures indicated that the eye temperature had warmed considerably over the previous six hours by 30 degrees Celsius. Movement was still toward the northwest, but the cyclone began to respond to an opening in the subtropical ridge axis and turned toward the north-northwest at 11/1200 UTC. By this time Sudal had failed to defend its super typhoon title and was downgraded at 0600 UTC. By the time the 1800 UTC warning was issued the MSW had fallen further to 110 kts.

(PAGASA had been issuing bulletins on Sudal since 10 April, assigning the name Cosme. Super Typhoon Sudal never ventured very far into PAGASA's AOR and reached its most westerly point (15.7N/130.9E) at 0600 UTC on 12 April. Warnings were issuing for a further two days until 14/0600 UTC, when Sudal exited the northeast quadrant of PAGASA's AOR. The highest sustained wind estimated by that agency was 100 kts (10-min avg) with an estimated minimum central pressure of 944 mb.)

Sudal underwent a brief rejuvenation period after the MSW had dropped to 105 kts at 0000 UTC 12 April. This resulted in a secondary peak of 125 kts being reached at 12/1200 UTC. Winds began to drop off again six hours later as the typhoon began to move to the right of its northward track. At 13/0000 UTC the eye of Sudal was situated some 765 nm southwest of Iwo Jima, moving north-northeastward at 5 kts. At 12/1800 UTC a large 45-nm symmetrical eye was observed in satellite images and this remained a prominent feature through the 13th. Further slow weakening occurred and the MSW was estimated at 115 kts at 13/1800 UTC.

In defiance of the increasingly hostile upper-level conditions, Typhoon Sudal held itself together during the 14th--in fact, by 1800 UTC the intensity still had yet to fall below 100 kts. However, by 15/0600 UTC Sudal had quickly succumbed to the increasing vertical wind shear and cooler SSTs with winds dropping to 65 kts. At this time the exposed LLCC was passing only 15 nm south of Iwo Jima. At 15/1200 UTC Typhoon Sudal was downgraded to tropical storm intensity as it sped east-northeastward at a little over 20 kts. Six hours later, Sudal had completed extratropical transition and the final warning was issued by JTWC, placing the center about 270 nm east-northeast of Iwo Jima. JMA, however, retained tropical classification for another 18 hours, declaring Sudal extratropical at 16/1200 UTC. The gale center continued speeding east-northeastward, crossing the International Dateline at 17/1800 UTC. The final reference to the system by JMA was at 0000 UTC on the 18th, the 40-kt gale center then being located well to the south of the Aleutian Islands.

Meteorological Statistics

At 0000 UTC on 9 April Typhoon Sudal passed 25 nm south of the island of Yap. The peak MSW recorded on the island was 79 kts with a peak gust of 117 kts at 08/2256 UTC. The lowest minimum SLP was 958.5 mb at 0050 UTC on 9 April.

Sudal was undergoing extratropical transition as it passed over Iwo Jima at 0600 UTC on 15 April. The MSW on the island reached 50 kts with the highest gust of 76 kts recorded at 15/0819 UTC. The strongest winds occurred in a region well away from the deep convection but were associated with a strong cumulus line. The MSLP recorded on Iwo Jima was 972 mb at 15/0612 UTC. (Thanks to Roger Edson for sending this information.)

Mark Lander's Post-storm Visit to Yap

The following report was sent by Mark Lander. A special thanks to Mark for sharing the report of his post-typhoon visit to Yap.

"A week ago Friday (April 09), Typhoon Sudal devastated Yap Island (9.5N/138.1E). I went out there as part of a team to perform a regional NWS Service Assessment and to gather meteorological data on the typhoon. The U. S. military and other U. S. government agencies have been busy with relief efforts to the island, and they are doing a good job over there helping the local inhabitants with the recovery process.

"Very nearly all wooden homes were damaged to some extent. Some of the worst damage occurred where the sea drove inland and smashed down the many houses that are built along the shoreline. Yap is famous for its large stone money (large rock disks with central holes for carrying on poles). Just south of Colonia--the main urban center on the central eastern coastal region--there is a large collection of the stone "coins" in a place known as the Yap Stone MoneyBank. The sea flooded in there at a standing level of about 6 feet, over-washed the many rows of stone money, and knocked them down. These can easily be righted, but the downed homes will take a bit more effort to bring back to habitable condition. Concrete structures fared well, and the new office of the National Weather Service was hardly touched (this served as a shelter for many people during the typhoon). Many people are homeless, but for the most part they are coping well.

"Flying over the island on approach to landing one is struck by the brownness of the terrain--a typical post-typhoon appearance due in part to the wind stripping the leaves off of the trees, and also due to a coating of sea salt that shrivels and kills any remaining green leaves. Mashed tangles of crushed and broken trees are seen at locations exposed to higher winds along the upslope regions of hills and along the shore line.

"One of the first efforts was to try to determine if the eye passed over any portion of the island. Very reliable eyewitness reports (pun inescapable) indicate that the eye was experienced briefly on the very southern-most tip of the island. Families sitting in the shade under surviving roofed structures were eager to comment on the experience. One young woman very convincingly described eye passage: for a brief period the wind stopped and the sun came out. The wind at first had been blowing from the northeast, then after the eye, it roared in directly from the sea (a southeast wind) towards her house. The sea inundated her property and over-washed the whole southern end of the island 50 yards or more inland to a run-up level of 12 feet above mean sea level. Dozens and maybe hundreds of reef fish (parrot fish, trigger fish, small groupers and others) lay dead along the base of a sea wall...not really sure how these died, but it must have been a miserable time for the sea critters as the white water thrashed inland.

"Yap is quite small: about 10 miles north-south and 3 or 4 miles east-west. It is completely surrounded by a fringing reef, and has a number of world-class dive sites. One of the mysteries of the typhoon brought to my attention (as soon as people knew that I was a weather guy) was that local divers noted that since the typhoon, the water had become as cold as they have ever experienced. A report (perhaps grown to the status of an urban legend) was that one group of divers noted that the water at dive depth (40-80 feet) was 12 degrees (F) colder than normal (72 F instead of the usual 84). I told them that typhoons cool the ocean surface as they pass, but that such a large magnitude cooling was truly remarkable. Another mystery presented to me was an observation of an unusual fog that had settled on the island and coastal regions in the mornings after the winds had died post-typhoon. Rising early one morning, I perhaps saw this "fog", and it was a whole lot of smoke from burning debris piles trapped under a shallow inversion perhaps 75 feet above the surface. It lay low in the bays and valleys with the hills poking above it into clean air. Can't say for sure whether by the time I arrived, I missed the formation of a true fog caused by the cold sea, or radiational night cooling. During the days it was hot and dry, and the roads had actually become dusty. There was some concern of wildfire if rains did not return and the typhoon debris became a dry tinder to fuel raging fires.

"Emergency crews quickly cleared the roads of fallen trees, and by the time that we arrived, we could drive to just about any location on the island. Getting clean drinking water out to the people was one of the first priorities. On my way over, there was little room in the C-130 among the pallets of bottled water.

"Although Yap is influenced by a few typhoons every year (mostly in the southern fringes of TC's that are passing by to the north), the island is rarely hit directly by an intense typhoon. Sudal is the worst typhoon to hit Yap in roughly 50 years. Only the older residents remember a typhoon that hit some time in the 1950's that was perhaps worse than Sudal.

"Despite the heavy damage, there are no known deaths directly attributable to the typhoon. This is quite remarkable, given the tales of many who were caught in their homes as the sea invaded, and then found themselves suddenly in water up to their waists or higher.

"On the way out from Yap, we dropped back down to about 100 feet above the water and made a fly-over of Ulithi Atoll (10.0N/139.8E). Ulithi was hit hard by Typhoon Lupit just this past December. Sudal passed far enough south to spare them another hard hit. The larger inhabited islets looked fine, and it was fun to see the kids running along the sand spits waving at the plane.

"Then it was back to Guam for a late night arrival, and business as usual."

Damage and Casualties

Sudal had a devastating effect on Yap. The typhoon damaged or destroyed 90% of property, private houses, and public utilities, and forced 900 people into shelters. Dehydration became a serious problem with fresh drinking water having to be brought in by air. Ninety percent of crops were completely destroyed. Coastal areas were devastated by the tidal surge, severely damaging seawalls. About 1000 persons were left homeless by the typhoon.

Although there has been no confirmed deaths attributable to the storm, some news articles have reported at least one.

Additional articles on Sudal's aftermath on Yap can be accessed at the following link:


(Report written by Kevin Boyle)

Source: Gary Padgett's Monthly Tropical Cyclone Summary - April 2004

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