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Atlantic disturbances not much of a threat today

By: Dr. Jeff Masters, 2:04 PM GMT on October 05, 2007

There's really not much new to report in the Atlantic today. A low pressure system over the northern Gulf of Mexico, (90L), continues to be unimpressive. Satellite loops show a small amount of heavy thunderstorm activity, to the northeast of the center. This activity is visible on Lake Charles long range radar. Water vapor satellite loops show plenty of dry air surrounding 90L, which should keep any development of the storm slow. The Hurricane Hunter aircraft scheduled to investigate 90L today was canceled. With 90L expected to make landfall Friday night near the Texas/Lousiana border, I don't expect the storm will become a tropical depression. However, it may be able to develop enough heavy thunderstorm activity today to cause some isolated flooding problems in southern Louisiana and northeast Texas.

Figure 1. Today's line up of tropical disturbances to watch.

Disturbance 92L east of the Bahamas
An area of heavy thunderstorm activity associated with a surface trough of low pressure (92L) near 22.4N 73W, in the southwestern Bahama Islands, has diminished. Wind shear of 20-30 knots has blown away nearly all of the heavy thunderstorm activity near the surface low pressure system, which has now reformed about 200 miles to the south of where it was last night. This morning's QuikSCAT pass showed some westerly surface winds over the southern Bahamas, which would aid in the formation of a new surface circulation under the heavy thunderstorms there. However, wind shear is still 20-25 knots today, and I don't expect any development until 92L can move into the Western Caribbean where wind shear is lower. This may occur Sunday. Another possibility is that a surface circulation just offshore of the Florida Keys, visible as a swirl of low clouds on this morning's visible satellite loop, could begin to develop. The computer models still indicate the possibility of a tropical storm forming in the Western Caribbean or southern Gulf of Mexico 2-7 days from now, but are much less insistent upon it. Upper air conditions are expected to be very favorable for tropical storm formation over the Western Caribbean and Gulf of Mexico for the next seven days, but nothing will form if we don't get a disturbance with some spin to it entering the region. A Hurricane Hunter aircraft is on call to investigate the Western Caribbean on Sunday, if necessary.

Disturbance 91L between Africa and the Lesser Antilles
A tropical wave (91L) near 12N, 49W, 900 miles east of the Lesser Antilles Islands, has become very disorganized. Wind shear is a high 20-30 knots over the system, and is expected to be 15-35 knots for the next five days. I don't expect 91L to develop.

Super Typhoon Krosa takes aim at Taiwan
Super Typhoon Krosa, a Category 4 storm with 150 mph winds, is bearing down on the northern portion of Taiwan. Latest Taiwan radar shows the eye of this huge storm approaching the island. Krosa is expected to hit Taiwan as a Category 3 typhoon, then brush the coast of Mainland China near Shanghai early next week as a Category 1 storm.

Figure 2. Radar image of Krosa from the Central Weather Bureau of Taiwan.

I'll have an update Saturday morning.

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.