21. Typhoon MUIFA (Unding/29w)                  Print this Article
>> November 14-26, 2004

Muifa: contributed by Macau, is a type of plum blossom which can withstand very cold weather--also represents a strong-minded Chinese.

Storm Origins

The disturbance that was to become Typhoon Muifa was first mentioned in JTWC's STWO at 1600 UTC 13 November when it was located approximately 215 nm north of Palau. At this time, development of a significant tropical cyclone was assessed as 'poor'. A TCFA was issued at 13/2000 UTC after the system showed a rapid spurt in development, and the first warning followed at 14/0000 UTC. At this time Tropical Depression 29W exhibited a partially-exposed LLCC with the strongest convection in the western semicircle. The disorganized-looking cyclone tracked westward, accelerating to around 14 kts along the southern boundary of the sub- ridge situated to the north, and became a 35-kt tropical storm at 14/1200 UTC when it was centred 550 nm east-southeast of Manila, Philippines. It was named Muifa at 14/1800 UTC after JMA upped their 10-min avg MSW to 35 kts. PAGASA had assigned the name Unding at 14/0000 UTC after the tropical cyclone had invaded their area of responsibility.

Synoptic History

At 0000 UTC 15 November Tropical Storm Muifa/Unding was moving west- northwest at 9 kts approximately 430 nm east-southeast of Manila, Philippines. The system didn't look that much more impressive with most of the deep convection separated from the LLCC. Also, it was discovered that the centre was positioned further east than previously analysed. The MSW remained at the 35-kt threshold for the rest of the day, although Muifa gradually became more organized. At 16/0000 UTC the tropical cyclone turned abruptly towards the north-northeast and decelerated to 4 kts. At this time it was relocated to a position 300 nm east of Manila, based on multi-spectral and microwave fixes which clearly showed the LLCC east-southeast of the deep convection. Muifa turned back onto a west-northwesterly heading and began to intensify. At the time of the next relocation at 16/0600 UTC, the MSW had climbed to 45 kts and this repositioning placed the centre closer to Manila, approximately 215 nm to the east, and under the deep convection. Muifa continued to strengthen and reached an intensity of 55 kts by 16/1800 UTC. At this time it appeared much better organised in satellite imagery.

At 0000 UTC 17 November Tropical Storm Muifa/Unding was creeping slowly westwards approximately 140 nm east of Manila, Philippines. It was upgraded to a 65-kt typhoon at 17/0600 UTC, but convection had waned somewhat despite the fact that microwave imagery revealed the early development of an eye. Erratic movement commenced at 17/1200 UTC and Muifa began the first leg of its clockwise loop which took a couple of days to complete. Strengthening had continued and by 17/1800 UTC the intensity had reached 90 kts. The centre of the typhoon was located 170 nm east-northeast of Manila at this time. Muifa's MSW reached 100 kts at 18/0000 UTC as it moved northwards at around 2 kts. The eye became better defined in multi-spectral imagery at 18/0600 UTC when the storm came to a virtual standstill. At 18/1200 UTC Muifa peaked at 115 kts before beginning a marked weakening phase at 18/1800 UTC. The MSW at this time had decreased to 105 kts. At this time, the northern eyewall had eroded with the strongest convection located in the southern portion. The tropical cyclone had veered to a slow southeasterly heading, seemingly moving away from the Philippines.

Typhoon Muifa/Unding weakened further to 95 kts at 0000 UTC 19 November as its heading slowly pivoted towards the southwest approximately 200 nm east-northeast of Manila, Philippines. The storm's forward motion began to increase at 19/0600 UTC as it sank south- southwestward towards southern Luzon. Muifa/Unding made landfall at 19/1300 UTC in the vicinity of Naga City with a MSW of 70 kts. The system staggered its way across the Philippine Archipelago, weakening as it went, and was downgraded to a 60-kt tropical storm at 20/0600 UTC. This intensity was maintained for the rest of the day. By this time, Muifa/Unding was centred 135 nm south-southwest of Manila, having emerged into the South China Sea. At 21/0000 UTC a small increase in the MSW to 65 kts meant that Muifa was upgraded back to typhoon intensity. Further strengthening occurred as the tropical cyclone made its way west to west- southwestwards across the warm waters of the South China Sea, and by 21/1800 UTC Muifa had re-strengthened into a 90-kt typhoon approximately 440 nm east of Ho Chi Minh City, Vietnam.

A slight weakening occurred at 0000 UTC 22 November as Muifa continued its way westward towards Vietnam. This heading was taking the storm into an environment of drier air and increasing vertical shear. At 22/0600 UTC the intensity was down to 75 kts, and by 22/1800 UTC Muifa was a minimal typhoon located approximately 320 nm east of Ho Chi Minh City, Vietnam. At this time, the cyclone's motion was still a rather wobbly west-southwest to southwest movement, and the forward speed had slowed to around 4 kts. Muifa held onto typhoon status until 23/1200 UTC when the MSW fell below 65 kts. The system continued to slowly sink generally towards the southwest, maintaining 55-kt winds for awhile during the 24th, but the intensity further dropped to 45 kts at 24/1200 UTC when it was centred 215 nm southeast of Ho Chi Minh City, Vietnam. The LLCC had, by this time, become partially-exposed and was moving in a different direction to that of the deep convection. At 24/1800 UTC microwave imagery indicated the LLCC was further west than previously analyzed, supporting a relocation to a position 160 nm south-southwest of Ho Chi Minh City.

At 0000 UTC 25 November Tropical Storm Muifa was picking up steam and had veered onto a westerly course at a forward speed of 21 kts. The system continued to weaken and was downgraded to tropical depression status at 25/1200 UTC after the MSW had fallen to 30 kts. Six hours later, Muifa was located off southern Thailand and passing approximately 250 nm south of Bangkok. Interaction with the terrain of Thailand finished the storm off and the best way to describe the LLCC was as a disorganized mess. At 26/0000 UTC Muifa turned northward into an environment of increased wind shear and as the intensity had fallen to 25 kts, JTWC issued the final warning on Typhoon Muifa. The final position was 120 nm south-southwest of Bangkok. JMA had ceased issuing bulletins at 25/1200 UTC.

At its peak intensity, Typhoon Muifa was representative of an average- sized storm with the radius of 64-kt winds extending up to 25 nm from the centre while gales lay up to 90 nm in the northern semicircle. The 34-kt wind radii in the southwestern and southeastern quadrants were 110 nm and 80 nm, respectively.

JMA's estimated peak intensity was 80 kts (10-min avg) with the lowest CP at 955 mb. This strength meant that JMA classified Muifa as a Severe Typhoon. Also, HKO, CWB and TMD estimated Muifa as an 80-kt typhoon. NMCC considered Muifa as a stronger 90-kt storm while PAGASA's maximum intensity during the period it was within their area of responsibility was 65 kts.

Damages and Casualties

The death toll reported from the Philippines, based on data released by the Philippines' National Disaster Coordinating Council (NDCC), stands at 68 dead, 160 injured, and 69 unaccounted for. A total of 26,238 houses were destroyed and 76,062 damaged.

Cost estimates include (in pesos):

Agriculture:              405.3 million 
Fisheries:                 76.1 million
Infrastructure:           371.0 million 
Transmission Facilities:   26.6 million 
School Facilities:        130.0 million 
Total:                  1,008.9 million

Typhoon Muifa also had a destructive impact on Vietnam. Floods and landslides triggered by the typhoon killed about 40 people, and 40 more people were reported missing. There were also many villages in the mountains which needed urgent relief but which could not be quickly reached. Hoi An, which is the town of world heritage, was hit by the flood, and more than 80 old houses were in danger of collapse.

Huang Chunliang Report from the Philippines

       === Brief Report on Typhoon UNDING {MUIFA} ===
              (Rainfall Obs from Philippines)

Only daily amounts >= 100 mm listed:

BORONGAN (WMO98553 11.65N 125.43E)          103.6 mm  [14/00-15/00Z]
CATANDUANES RADAR (WMO98447 13.98N 124.32E) 246.4 mm  [15/00-16/00Z]
VIRAC (WMO98446 13.58N 124.23E)             207.3 mm  [15/00-16/00Z]
CATARMAN (WMO98546 12.50N 124.63E)          122.0 mm  [15/00-16/00Z]
CATANDUANES RADAR (WMO98447 13.98N 124.32E) 182.4 mm  [16/00-17/00Z]
PILI (WMO98442 13.57N 123.27E)              151.2 mm  [16/00-17/00Z]
DAET (WMO98440 14.13N 122.98E)              127.6 mm  [16/00-17/00Z]
VIRAC (WMO98446 13.58N 124.23E)             123.0 mm  [16/00-17/00Z]
SAN JOSE (WMO98531 12.35N 121.03E)          171.4 mm  [20/00-21/00Z]
TAYABAS (WMO98427 14.03N 121.58E)           103.1 mm  [20/00-21/00Z]

Huang Chunliang Report from Thailand

      === Brief Report on Typhoon MUIFA from Thailand ===

1. Landfall

According to the TMD warnings, Tropical Depression MUIFA 
made landfall near Amphoe Tha Chana, Surat Thani Province 
around 25/1500 UTC with a MSW of 30 knots.

2. Rainfall (Only 24-hr amounts >= 100 mm listed)

PRACHUAP KHIRIKHAN (WMO48500 11.83N 99.83E) 173.4 mm [25/00-26/00Z]
PRACHUAP KHIRIKHAN (WMO48500 11.83N 99.83E) 251.5 mm [25/06-26/06Z]
PRACHUAP KHIRIKHAN (WMO48500 11.83N 99.83E) 235.8 mm [25/18-26/18Z]

Michael Padua Report from Naga City, Philippines

Michael V. Padua, an amateur meteorologist in Naga City and 
owner of the Typhoon 2000 website, had a Close Encounter of 
the Third Kind with Typhoon Muifa when the cyclone made 
landfall near his home. Michael gained a considerable amount 
of publicity when, convinced that the typhoon was headed for 
the Naga City area but with the official PAGASA warnings 
continuing to forecast the storm to head northwestward away 
from the region, called the mayor of Naga City and advised 
him to make emergency preparations for Typhoon Muifa.  
Because of Michael's action, residents of Naga City were 
somewhat better prepared for the arrival of the typhoon 
than they would have been otherwise.

Following is a portion of Michael's write-up about his 
experiences (slightly edited):

   "As I woke up around 6:30 in the morning (2230 UTC) of 
19 November, I quickly opened the monitor and refreshed 
the browser to get the latest satellite image and GOES 
animation that showed that the system was starting to 
track more southerly.  This prompted me to call our local 
PAGASA (office) to advise them about the imminent danger.  
They told me that their main office in Manila still believed 
that the storm would move west-northwest.  At around 10:00 
AM (0200 UTC), I drove to our school (Naga College Founda-
tion) and stepped into my office where I got the latest 
satellite image which continued to show the southward drift 
of Muifa accelerating a bit--that was barely 12 hours before 
the eyewall passage over Naga.  I had already taken some 
video of the approach of the outer bands.  The pressure 
reading at the time was still high (1008.7 hPa) with winds 
gusting up to 14 kts, blowing from the northwest.

   "As of 11:00 AM (0300 UTC), I received the latest PAGASA 
bulletin that still showed no Philippine Storm Warning 
Signals raised over our area.  This prompted me again to call 
up our local PAGASA (office) for the second time around.  
Then at around 3:00 PM (0700 UTC), I went home to have a late 
lunch and created a last-minute animation of Muifa. After 
finishing the animation it was already 4:00 in the afternoon!
That was barely six hours before Muifa's destructive approach.  
By that time the pressure had already dropped to 1004.7 hPa 
with northwesterly winds reaching 22 kts.  I checked the 3:30 
PM (0730 UTC) satellite image which showed that Muifa had 
accelerated further towards the south to south-southwest.  
I decided to call our city mayor to advise him that we must 
prepare for the possible nighttime approach of Muifa. I also 
told him that PAGASA had not yet raised any storm signals over
our area.  I explained to him that our city should be under 
Storm Signal Number 3, which means that winds of more than 54 
kts could be expected in at least 18 hours, and we were only 
six hours away from the destructive winds!

   "The mayor thanked me right away and called an emergency 
meeting, also notifying the radio stations regarding the 
danger Naga had to face.  Around 4:30 in the afternoon, I 
quickly drove back to my office, where many students of our 
college were waiting for me to post what signal we were in.  
As I plotted the latest position of Muifa (based on the most 
recent satellite image), I posted the Signal Number 3 an
hour before the official PAGASA bulletin went out!  At 
that time all classes and offices were suspended.  Then as 
the PAGASA bulletin went out around 5:30 PM--the signal was 
still Number 2!

   "At around 10:00 in the evening, the worst of the typhoon 
arrived! My Davis Vantage Pro weather station recorded 10-min 
avg winds of up to 43 kts (NW to N) with gusts reaching 71 kts 
(north).  The highest rain rate was 18 inches (457 mm) per 
hour, and the lowest pressure recorded was 986.1 hPa at 10:14 
PM (1414 UTC).  I heard the sound of flying debris and falling 
trees outside the house as the winds continued to scream.  I 
was then waiting for the sudden lull, but there was no calm.  
Then, at 11:00 PM the storm's eyewall began to move farther 
away from Naga, as confirmed by the rapidly increasing pressure 
which was already up to 992.7 hPa.  The 10-min avg winds had 
diminished to only 27 kts, blowing from the north to northeast
(gusting to only 38 kts).  By midnight on 20 November the winds 
had dramatically died down to an average of only 16 kts coming 
from the east.  At around 02:00 AM it was eerily calm as if 
nothing had happened!  I took a 4-hour sleep afterwards."

  To recap, following are the particulars of Michael's location 
and his observations:

Date:        19-20 November 2004
Location:    Naga City, Philippines
Lat/Lon:     13.6N/123.2E
Instrument:  Davis Vantage Pro Weather Station (March 2004 Model)

Highest Wind Speed (gust):   North 71 kts at 1400 UTC 19 November
Lowest Barometric Pressure:  986.1 hPa at 1414 UTC 10 November
Highest Rainfall Rate:       457 mm/hour at 1343 UTC 19 November
Storm Total Rainfall:        306.5 mm (14-20 November)

   Michael's excellent full report (with graphics) on Typhoon 
Muifa/Unding can be found at the following link:


(Report written by Kevin Boyle with significant contributions by Huang Chunliang and Michael V. Padua)

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

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