Déjà Vu: Category 3 Megh Slams Yemen Island; Bahamas Disturbance 94L May Develop

By: Jeff Masters , 5:57PM,GMT on November 8,2015

Tropical Cyclone Megh powered ashore over Yemen's Socotra Island on Sunday morning as a major Category 3 storm with 125 mph winds. Megh could well have been a Category 4 storm at landfall, since satellite estimates of small storms like Megh are subject to large errors. Megh's passage over the island has disrupted the storm some, and the Joint Typhoon Warning Center (JTWC) estimated the storm's peak winds at 115 mph at 7 am EST Sunday. Interaction with land, entrainment of dry air from the nearby deserts, and encounters with cooler patches of water upwelled last week by the passage of Tropical Cylcone Chapala should continue to weaken Megh. By the time it reaches the south Yemen coast between Mukalla and Aden sometime on Tuesday, Megh will likely be at tropical storm strength.


Figure 1. MODIS image of the eye of Tropical Cyclone Megh making landfall on Yemen's Socotra Island on November 8, 2015. At the time, Megh was a Category 3 storm with 125 mph winds. Image credit: NASA.


Figure 2. Tropical Cyclone Chapala as seen by the MODIS instrument on November 1, 2015. At the time, Chapala was passing just north of Yemen's Socotra Island as a Category 3 storm with 120 mph winds. Image credit: NASA.

Twin major hurricanes in the Arabian Sea: unprecedented in the historical record
Megh is the second major Category 3 or stronger tropical cyclone to affect Yemen this month. Just a week ago, Tropical Cyclone Chapala took advantage of the the warmest waters ever recorded in the Arabian Sea at this time of year to intensify into a top-end Category 4 storm with 155 mph winds (1-minute average). This made Chapala the second strongest tropical cyclone on record in the Arabian Sea, behind Category 5 Cylcone Gonu of 2007, the only Category 5 storm ever recorded in the Arabian Sea (Gonu peaked at 165 mph winds). Chapala went on to devastate Yemen's Socotra Island and mainland Yemen near the port city of Mukalla on November 3, killing at least eight people and causing widespread destructive flooding. According to NOAA's Historical Hurricanes tool, prior to this year, there had only been five major Category 3 or stronger tropical cyclones recorded in the Arabian Sea since accurate satellite records began in 1990, and an additional Category 3 storm that occurred in 1977. Thus, two major hurricanes in one month in the Arabian Sea is a remarkable occurrence.


Figure 3. Latest satellite image of 94L.

94L could develop into a tropical depression near the Bahamas
A well-organized area of heavy thunderstorms near the Southeast Bahamas and Turks and Caicos Islands (Invest 94L) is associated with an area of low pressure headed west-northwest at about 15 mph. Satellite loops on Sunday morning showed 94L had a modest degree of spin, and a moderate-sized area of heavy thunderstorm activity. Wind shear was a moderate 10 - 20 knots over 94L, and water temperatures were record-warm for this time of year, near 29°C (84°F). The 8 am EDT Sunday run of the SHIPS model predicted that wind shear near 94L would remain moderate through Wednesday and ocean temperatures would be above the 80°F threshold for tropical storm formation--conditions which should allow 94L to develop into a tropical depression by Wednesday, though waer vapor satellite loops show that there is some dry air to the west of 94L that could slow down development. In their 1 pm EST Sunday Tropical Weather Outlook, NHC gave 94L 2-day and 5-day odds of development of 70%. The disturbance should continue heading west-northwest through Monday afternoon, spreading heavy rain showers into the Central Bahamas. By Monday night or Tuesday morning, 94L should turn sharply to the north just before reaching the northwest Bahamas, as a trough of low pressure passing to the north pulls the disturbance northwards. This motion should keep 94L from having any direct impacts on the U.S. East Coast. 94L will then turn to the north-northeast or northeast by Tuesday afternoon, and could bring heavy rains to Bermuda on Wednesday. About half of the members of the GFS and European ensemble models develop the system into a tropical depression, though the operational versions of these models were lukewarm on the development prospects. Should 94L intensify into a tropical storm, it would be called Tropical Storm Kate. A hurricane hunter flight is scheduled to investigate 94L on Monday morning.

Jeff Masters