Category 5 Super Typhoon Haiyan Headed Towards the Philippines

Evacuations are underway in the Philippines Islands as extremely dangerous Category 5 Super Typhoon Haiyan heads west-northwest at 20 mph towards the islands. Haiyan, which is the Chinese word for a petrel seabird, is referred to as "Yolanda" in the Philippines, and became a Category 5 storm with 160 mph winds at 12 UTC (7 am EDT) Wednesday. Haiyan became a Cat 5 at an unusually low latitude (7.9°N), but this is not a record. The most southerly Cat 5 on record was Super Typhoon Louise of 1964 (7.3°N), followed by 2012's Super Typhoon Bopha (7.4°N.) Haiyan is the fourth Category 5 storm in the Western Pacific and fifth on Earth so far in 2013. This is the highest number of Cat 5s since 2009, which had four Cat 5s in the Western Pacific and one in the Eastern Pacific. Since 2000, Earth has averaged 4.4 of these mightiest of tropical cyclones per year. The record for Cat 5s in a year is twelve, set in 1997, when an astonishing ten Cat 5s occurred in the Western Pacific. The Atlantic has not had a Category 5 storm since Hurricane Felix of 2007, making the past six years the longest stretch without a Cat 5 since 1981 - 1987.


Figure 1. Visible satellite image of Haiyan taken at 1:57 UTC November 6, 2013. The islands at the left are part of the Caroline Islands, which recorded sustained winds of 37 mph, gusting to 47 mph, at 15 UTC November 7, 2013. Image credit: University of Wisconsin CIMSS.

Satellite loops show that Haiyan is a spectacular typhoon with a tiny pinhole eye just 9 miles in diameter. A buoy (station 52087) reported a pressure of 956 mb and sustained WNW winds of 67 mph at 1000 UTC (5 am EDT) Tuesday morning in the southern eyewall of Haiyan. With warm waters that extend to great depth, low wind shear, and excellent upper-level outflow, Haiyan will likely stay at Category 4 or 5 strength until landfall occurs between 03 - 06 UTC Friday in the central Philippine islands of Samar or Leyte. The only brake on Haiyan's strength over the next day might be an eyewall replacement cycle, which will be capable of causing a temporary weakening of perhaps 20 mph in the storm's winds.


Figure 2. Predicted rainfall from the 06Z November 6, 2013 run of the HWRF model, for the 126-hour period ending at 12Z November 11, 2013. A 100-mile wide swath of 8+ inches of rain (medium dark red colors) is predicted to cross the Central Philippines and Northern Vietnam. Image credit: NOAA/NCEP/EMC.

Haiyan a major storm surge threat
The storm surge potential for Haiyan is very concerning, if the typhoon maintains its current forecast track and makes landfall on Leyte Island. This track would push a dangerous storm surge into the funnel-shaped Leyte Gulf, which comes to a point in Tacloban, population 221,000, the capital of the province of Leyte. Much of Tacloban is at elevations less than ten feet, and the experimental storm surge forecasts from the European Commission's Joint Research Centre HyFlux2 model made on November 5 and November 6 have called for a storm surge of 5 - 10 feet (1.6 - 2.9 meters) to hit Tacloban. This model has not been verified for the Philippines, and it is not unreasonable to speculate that the storm surge could be higher along a 20-mile swath of the coast to the north of where the eye hits, if it indeed comes ashore in Leyte. If the eye strikes farther north on Samar Island, this would not generate as high of a storm surge, since there is no triangular-shaped bay there to funnel the waters to a peak. Storm surge forecasts made by the Philippines' Project NOAH at 00 UTC November 6, 2013, are calling for no more than 2 meters (6.6 feet) of surge throughout the Philippines from Haiyan.


Figure 3. Elevation map of Leyte Island (left) and Samar Island (top) in the Philippines. Much of the capital of Leyte, Tacloban, is at an elevation less than 4 meters (13'), red to dark red colors. The predicted path of Haiyan’s eye in the 21 UTC November 6, 2013 Joint Typhoon Warning Center advisory is shown. Image credit: Globalwarmingart.com.

Haiyan the fifth named storm to hit the Philippines in 2013
Haiyan will be the fourth typhoon and fifth named storm to hit the Philippines this year. The others were:

Tropical Storm Rumbia, which hit the island of Samar on June 29 as a tropical storm, killing six.
Typhoon Nari, which hit Luzon on October 11 as a Category 3 typhoon with 115 mph winds, killing five.
Typhoon Utor, which hit Luzon on August 12 as a Category 4 typhoon with 140 mph winds, killing fourteen and causing $25 million in damage.
Typhoon Krosa, which hit northern Luzon on October 31 as a Category 2 typhoon with 105 mph winds, killing five and doing $5 million in damage.

The Philippines lie in the most tropical cyclone-prone waters on Earth, and rarely escape a year without experiencing a devastating typhoon. Usually, these storms impact the northern Philippine island of Luzon, but last year, Earth's deadliest weather disaster of 2012 occurred on the southern Philippine island of Mindanao, where Super Typhoon Bopha struck as a Category 5 super typhoon with winds of 160 mph (260 km/h), on December 3. Bopha made two additional landfalls in the Philippines, on central Visayas and on Palawan, on December 4. The typhoon left 1901 people dead, mostly on the island of Mindanao, making Bopha the 2nd deadliest typhoon in Philippine history. With damages estimated at $1.7 billion, Bopha was the costliest natural disaster in Philippines history. However, that mark was eclipsed just over four months ago, when torrential rains in the wake of Typhoon Trami inundated the capital of Manila and large areas of Luzon, killing 27 people and causing damages estimated at $2.2 billion by Aon Benfield.


Figure 4. Torrential rains, due, in part, to moisture from Typhoon Trami, fell in the Philippines August 18 - 21, 2013, causing massive flooding on Luzon Island that cost $2.2 billion. Twenty-seven people were killed, and 60% of metro Manila was under water at the peak of the flood. According to EM-DAT, the International Disaster Database, this flood would be the most expensive natural disaster in Philippine history. In this photo, pedicabs and makeshift rafts ferry office workers and pedestrians through flood waters that submerged parts of the financial district of Makati on August 20, 2013 in Makati City south of Manila, Philippines. Image credit: Dondi Tawatao/Getty Images)


Figure 5. Super Typhoon Bopha as seen from the International Space Station on December 2, 2012. At the time, Bopha had top sustained winds of 150 - 155 mph. Image credit: NASA.

Tropical Depression 30 a heavy rainfall threat for Southeast Asia
Tropical Depression 30 is making landfall over southern Vietnam, and will bring heavy rains of 8+ inches to portions of Vietnam, Cambodia, Laos, and Thailand over the next few days. The storm is expected to dissipate over Southeast Asia by Thursday.

Jeff Masters