Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 2:58 PM GMT on August 10, 2014
A tropical wave that moved off the coast of Africa on Saturday was located near 11°N, 21°W on Sunday morning, and was designated Invest 94L by NHC . Satellite loops show the wave has a modest amount of spin and respectable amount of heavy thunderstorms. Water vapor satellite images and the Saharan Air Layer analysis show that 94L is located in a fairly moist environment, with the dry air coming off of Africa located well to the north and west of the disturbance. Wind shear was a high 25 - 30 knots, but the 8 am EDT Sunday run of the SHIPS model predicted that wind shear would fall to the moderate range on Monday afternoon, then to the low range on Tuesday afternoon. The wave is headed west at 15 - 20 mph, and should arrive in the Lesser Antilles Islands by Saturday, according to the Sunday morning runs of the GFS and European models. None of the reliable computer models for predicting tropical storm formation develop 94L, but about 1/3 of the 20 members of the GFS model ensemble show development late this week (the GFS ensemble is a set of 20 runs of the GFS model done at lower resolution with slightly different initial conditions to generate an uncertainty "plume" of model runs.) In their 8 am EDT Sunday Tropical Weather Outlook, NHC gave 94L 2-day and 5-day development odds of 10% and 30%, respectively. Mid-August is the time when the Atlantic hurricane season kicks into high gear, and 94L is definitely a disturbance we need to watch.
Figure 1. True-color MODIS image from approximately 9 am EDT August 10, 2014, showing Invest 94L off the coast of Africa, south of the Cape Verde Islands. Image credit: NASA.
Tropical Storm Halong hits Japan
Slow-moving Tropical Storm Halong finally made landfall in Southern Japan near Aki city, Kōchi Prefecture, at approximately 5 pm EDT Saturday (6 am Sunday in Japan.) Despite weakening to a 70 mph tropical storm before landfall, Halong dumped extremely dangerous heavy rains over Southern Japan, with storm total rainfall amounts in excess of one meter in some locations. A rare "emergency weather warning" (tokubetsu keihō) for the Mie Prefecture was issued on Saturday by the Japan Meteorological Agency (JMA). Hakusan in the Mie Prefecture had nearly 17 inches of rain on Saturday, breaking its all-time 24-hour rainfall record set just last year in Typhoon Man-yi. The top winds near landfall, reported at Cape Muroto, were 94 mph, gusting to 117 mph (42.1 m/s gusting to 52.5 m/s). At least nine people were killed and 70 injured in the floods, according to the Japan Times.
Figure 2. Radar image of Tropical Storm Halong making landfall on the coast of Japan at 6:50 pm EDT August 9, 2014 (05:50 JST August 10) . Halong had 70 mph winds at the time. Image credit: Japan Met Agency.
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