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Haiyan Finally Dying; Somalia's Deadliest Tropical Storm on Record Kills 100

By: Dr. Jeff Masters, 5:07 PM GMT on November 11, 2013

Typhoon Haiyan made landfall on the northern Vietnam coast near the Chinese border as a Category 1 storm with 75 mph winds near 21 UTC Sunday. At least 13 people died and 81 were injured in Vietnam from the storm, said the Voice of Vietnam, the country's national radio broadcaster. Satellite loops show that Haiyan has now pushed into Southeastern China, where 4 - 8" of rain will likely cause moderate flooding. Huge 26-foot waves from Haiyan swept 16 people out to sea in Taiwan on Sunday, killing 8 of them, the Chinese news agency Xinhua reported. Haiyan has been downgraded to a tropical depression and will dissipate later today, finally bringing to an end its catastrophic march through Asia.

Figure 1. Tropical Storm Haiyan over China, as seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite at 05:45 UTC on November 11, 2013. Image credit: NASA.

Third deadliest typhoon in Philippines history
With an official death toll of 1,774, Haiyan already ranks as the 3rd deadliest typhoon in Philippine history. The deadliest typhoon in Philippine history was Typhoon Thelma of 1991, which killed between 5101 - 8000 people, reports wunderground's weather historian Christopher C. Burt in his latest post on Philippines typhoon history. The greatest death toll from Haiyan is likely to be in the capital of Leyte, Tacloban (population 221,000), which received a direct hit from Haiyan's northern eyewall.

Figure 2. In this handout from the Malacanang Photo Bureau, an aerial view of buildings destroyed in the aftermath of Typhoon Haiyan on November 10, 2013 over the Leyte province. (Getty/Malacanang Photo Bureau)

Tropical disturbance 90W bringing heavy rain to the Philippines
A tropical disturbance centered about 200 miles east of the Philippines Island of Mindanao (Invest 90W), is bringing heavy rains to Mindanao, and has the potential to become a tropical depression by Tuesday. The disturbance has developed an elongated surface circulation and a respectable amount of heavy thunderstorm activity. Wind shear is low, but the disturbance is too close to the Equator intensify quickly, since the storm will not be able to leverage Earth's spin to get itself spinning. The disturbance has a high chance of development, according to Monday's 06 UTC Western Pacific Tropical Weather Discussion by the Joint Typhoon Warning Center (JTWC). The heaviest rains of 3 - 6" from 90W will stay to the south of the typhoon-devastated areas of the Central Philippines, but 2 - 4" of rain could fall in the disaster zone on Tuesday and Wednesday, hampering relief efforts. I give a 70% chance that 90W will be classified as a tropical depression by JTWC by Tuesday. The Japan Meteorological Agency is already classifying 90W as a tropical depression, and the system is being referred to as Tropical Depression Zoraida by the Philippines Atmospheric Geophysical and Astronomical Services Administration (PAGASA.)

How strong were Haiyan's winds?
Haiyan's strongest winds occurred on the south shore of Samar Island and the city of Guiuan (population 47,000), where the super typhoon initially made landfall with 1-minute average winds estimated at 195 mph. This estimate came from the Joint Typhoon Warning Center, and was based on satellite measurements. We have no ground level or hurricane hunter measurements to verify this estimate. Typhoon and hurricane maximum wind speed estimates are only valid for over water exposure, and winds over land are typically reduced by about 15%, due to friction. This would put Haiyan's winds at 165 mph over land areas on the south shore of Samar Island. This is equivalent to a high end EF-3 tornado, and damage photos from the town do appear to show EF-3 damage--though much of the worst damage appears to be due to the storm surge. A new Doppler radar that was scheduled to go into operation in 2014 was blown off the tower it was installed on in Guiuan, and was not operational during the storm, unfortunately.

The Japan Meteorological Agency (JMA), which uses their own techniques to estimate typhoon strength via satellite imagery, put Haiyan's peak strength at 125 knots (145 mph), using a 10-minute averaging time for wind speeds. The Philippines weather agency (PAGASA) also uses a 10-minute averaging time for their typhoon wind advisories, and also had a lower estimate of Haiyan's winds. Winds estimated by either JMA or PAGASA for Haiyan have appeared in the media, resulting in some confusion about what the typhoon's winds were at landfall. The averaging time used by JTWC and NHC is 1-minute, resulting in a higher wind estimate than the 10-minute average winds used by JMA and PAGASA in their advisories. To convert from 10-minute averaged winds to 1-minute average, one conversion factor that is commonly used is to multiply by 1.14--though lower conversion factors are sometimes used.

JMA satellite strength estimates are consistently much lower than those from JTWC for high-end Category 5 strength typhoons, and JTWC estimates are the ones most commonly used by the hurricane research community. The JMA began issuing typhoon advisories in 1976, and a searchable database of their typhoon database at digitaltyphoon.com reveals that Haiyan is tied for second place as the strongest typhoon in history, when measured by wind speed. Haiyan was the strongest landfalling typhoon they have rated.

I asked Stormchaser Jim Edds, who rode out the storm at a hotel in Tacloban, what the lowest pressure reading he took was from his hand-held pressure sensor. You can watch his remarkable eyewall video, available here. At one point during the ordeal, he was forced to jump into the hotel pool to escape wind-blown debris. Via email, he told me, "My barometer stopped after I jumped in the pool.  It wasn't waterproof but I recall it was 972 mb but the storm got a whole lot worse and I had a chance to get out of the pool and make a run for it." He just posted a new video showing the aftermath of the devastating storm. A second group of storm chasers in Tacloban, James Reynolds, Josh Morgerman and Mark Thomas, did record pressure data, and will make graphs of the data available on Tuesday.

Video 1. Storm chasers James Reynolds, Josh Morgerman and Mark Thomas were in the capital of Leyte Province, Tacloban, which received a direct hit from Super Typhoon Haiyan. This video shows some of the extreme winds of the eyewall, as filmed by James Reynolds. You can read an account of their escape from Tacloban on CNN.

Video 2. Aftermath of Haiyan in Tacloban, as filmed by James Reynolds.

The Philippine Red Cross is appealing for donations.

Portlight disaster relief charity is reaching out to disability organizations in the Philippines to provide durable medical equipment. and welcomes donations.

Google Person Finder: Typhoon Yolanda - Google.org

Haiyan Links
Wunderblogger Lee Grenci discusses mesovorticies in the eye of Haiyan in his latest post.
Wunderground's weather historian Christopher C. Burt reviews the Philippine's typhoon history.
The University of Wisconsin CIMSS Satellite Blog has a great collection of satellite images of Haiyan.
NOAA's Michael Folmer has a post showing the unusual burst of lightning that occurred at landfall in Haiyan.
Hurricanes and Climate Change: Huge Dangers, Huge Unknowns, my August 2013 blog post.
Storm Chaser James Reynolds on Twitter, from Tacloban, Leyte.
Storm Chaser Jim Edds on Twitter, from Tacloban, Leyte.

Figure 3. Tropical Cyclone 3A over Somalia, as seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite at 07:35 UTC on November 11, 2013. Image credit: NASA.

Rare tropical storm kills 100 in Somalia
Tropical Storm Three in the Arabian Sea made landfall in Somalia, Africa on Sunday, bringing sustained winds of 45 mph to the coast and heavy rains inland. The rains triggered flash floods that killed about 100 people, said President Abdirahman Mohamud Farole. According to the International Disaster Database, EM-DAT, this is the deadliest tropical cyclone in Somalia's history, tied with Tropical Cyclone ARB04 of 1994. According to the International Best Track Archive of storm tracks, only four other tropical storms have hit Somalia since accurate satellite measurements began in 1966: Tropical Cyclone Murjan of 2012, Tropical Cyclone ARB04 of 1994, Tropical Cyclone 12A of 1994, and Tropical Cyclone 4B of 1984.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.