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 , 2:24 PM GMT on September 22, 2007
Tropical Depression Ten moved ashore last night over the Florida Panhandle, bringing rains of 1-5 inches over the region (Figure 1). The most serious weather associated with the depression occurred when a tornado ripped through Eustis, Florida at 11 pm Friday night. The EF-1 tornado had winds up to 105 mph, and damaged about 100 homes. The remnants of TD Ten are over southern Mississippi this morning, and additional severe weather or heavy rain is not expected.
Figure 1. Estimated rainfall for TD 10 from the Tallahassee, Florida radar.
Western Caribbean disturbance 94L
An area of disturbed weather in the western Caribbean between the Yucatan Peninsula and Jamaica is associated with a surface trough of low pressure. NHC designated this area "94L" this morning. Satellite loops show that the heavy thunderstorm activity has increased today in the region, but remains disorganized. A buoy in the region recorded sustained winds of 31 knots, gusting to 35 at 4:50 am EDT. The winds have since subsided to 20 knots. Cancun radar shows heavy rains have already moved ashore over the eastern Yucatan. This morning's QuikSCAT pass showed no signs of a circulation, and very little evidence of even a wind shift in the region. Thus, the earliest I expect 94L can become a tropical depression is Sunday afternoon. An Air Force Hurricane Hunter aircraft is scheduled to investigate 94L Sunday afternoon.
This disturbance will bring heavy rains to Belize, Cozumel, Cancun, and western Cuba today as it crosses the Yucatan Peninsula. Moisture streaming northwards from the disturbance will also cause locally heavy rains across the Florida Peninsula. Wind shear has dropped to about 10 knots over the disturbance, and the NOGAPS and GFS models predict this shear will stay low enough to allow a tropical depression to form on Sunday when 94L crosses into the Gulf of Mexico. By Monday afternoon, my best guess is that 94L will make landfall near the Texas/Louisiana border. That doesn't give it much time to organize into a tropical depression or tropical storm. Today's 12Z (8 am EDT) run of the GFDL model did not develop 94L. The 12Z SHIPS model developed it into a 45-mph tropical storm by Monday morning. Regardless, Texas and/or Louisiana can expect very heavy rains Monday and Tuesday from this system.
Elsewhere in the tropics
A few clumps of heavy thunderstorm activity exist along the Intertropical Convergence Zone (ITCZ), about 800-1200 miles east of the southernmost Lesser Antilles. This activity is moving west at 10-15 mph, and is very disorganized. Nevertheless, the region is under only about 10 knots of wind shear, so we will need to watch this area for development. A tropical wave near 6N, 23W, about 60 miles south of the Cape Verdes Islands off the coast of Africa, has some vigorous thunderstorm activity associated with it. This morning's 4:30 am EDT ASCAT pass showed a nearly complete circulation, and visible satellite images also show a fair bit of spin. This wave has the potential to develop into a tropical depression early next week as it moves westward at 15 mph.
I'll be traveling Sunday, and will not post a blog if the Western Caribbean disturbance fizzles. Otherwise, I'll post something late Sunday afternoon when the Hurricane Hunter mission sends back data.
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Light Freezing Rain Mist