Gabrielle gone; next system to watch is 91L

By: Dr. Jeff Masters , 2:22 PM GMT on September 10, 2007

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Tropical Storm Gabrielle limped ashore over North Carolina's Outer Banks Sunday afternoon as a minimal tropical storm, bringing wind gusts up to 61 mph. Strong upper-level winds ripped Gabrielle apart as it came ashore, and has reduced it to a tropical depression. Diamond Shoals buoy off the coast at Cape Hatteras recorded a few hours of minimal tropical storm force winds (35 knots, 40 mph), and 15 foot waves. The biggest impact from the storm was some isolated minor flooding due to rains around eight inches. Gabrielle's rains did not stretch far enough inland to have a significant effect on North Carolina's drought, unfortunately. Here is a list of the wind and rainfall totals for the storm:

Ocracoke... ... ... ... 61 mph gust
Ocracoke COOP... ... ... 56 mph gust
Cape Hatteras... ... ... 53 mph gust and 39 mph 2 minute sustained wind
Beaufort... ... ... ... 44 mph gust and 33 mph 2 minute sustained wind
Indian Beach... ... ... 42 mph gust
Duck... ... ... ... ... 32 mph gist
Kill Devil Hills... ... 32 mph gust
Surf City... ... ... ... 31 mph gust
New Bern... ... ... ... 30 mph gust

Diamond buoy... ... ... 52 mph gust
5 SE New River buoy... 38 mph gust
Cape Lookout buoy... 35 mph gust
Duck buoy... ... ... ... 35 mph gust

Heavy rain fell over parts of eastern Carteret and Craven counties
where isolated reports of 6 to 8 inches and localized road flooding
have been reported... primarily across eastern Carteret County.
Elsewhere rainfall was generally less than 1 inch.

Harlowe (Cocorahs)... ... 8.60 inches
6 mi north Beaufort... ... 8.30 inches
Beaufort ASOS... ... ... ... 7.43 inches
Morehead City... ... ... ... 7.07 inches
Morehead City... ... ... ... 6.93 inches
Newport (NWS)... ... ... ... 5.36 inches
Cherry Point ASOS... ... ... 4.52 inches
Indian Beach... ... ... ... 2.19 inches
New Bern ASOS... ... ... ... 1.89 inches
Perrytown COOP... ... ... ... 1.33 inches
New Bern ... ... ... 1.12 inches
Jacksonville COOP... ... ...0.62 inches
Greenville COOP... ... ... 0.45 inches
Surf City... ... ... ... ... .0.43 inches
Ocracoke coop... ... ... ... 0.34 inches
Cape Hatteras ASOS... ... 0.23 inches


Figure 1. Total precipitation from Gabrielle from the Morehead City radar. Rainfall amounts of up to 8.6 inches fell in isolated regions.

Tropical wave in the mid-Atlantic (91L)
A strong tropical wave near 10N 38W, about 1000 miles west-southwest of the Cape Verdes Islands off the coast of Africa, is headed west to west-northwest at 10-15 mph. This system (91L) has the potential to develop into a tropical depression later this week. This morning's QuikSCAT pass showed a broad, elongated circulation and top winds of 25 mph. Satellite loops show some disorganized clumps of heavy thunderstorm activity. The disturbance is under about 15 knots of wind shear. Shear is forecast to remain near 15 knots over three days, which may allow some slow development. Later in the week, shear is expected to drop below 10 knots, and this could lead to a better chance of development. Both the HWRF and GFDL models predict that this will be a hurricane five days from now. This seems over-aggressive, given the wave's current state of disorganization, and the shear forecast. I think the earliest this would become a tropical depression is Wednesday.

A large extratropical storm over the mid-Atlantic between Europe and the U.S. is expected to pull 91L on a more northwesterly track by mid-week. This would put 91L in a position to threaten the northern Lesser Antilles Islands seven days from now.


Figure 2.Today's lineup of systems to watch.

Gulf of Mexico disturbance (90L)
An area of disturbed weather in the southern Gulf of Mexico (90L) remains disorganized. Wind shear is not a major impediment to development--upper level winds from the north are creating about 10-15 knots of wind shear over the region, and this shear is expected to remain below 15 knots through Wednesday. However, given the extremely disorganized appearance of this disturbance on satellite loops, any development should be slow to occur. This system is headed west-northwest at 10-15 mph towards Texas.

Elsewhere in the tropics
An area of disturbed weather near the northern Lesser Antilles Islands (designated 92L by NHC yesterday) has become disorganized and is no longer a threat. A new tropical wave with a closed circulation moved off the coast of Africa yesterday, but currently does not have much thunderstorm activity associated with it.

I'll have an update Tuesday morning.
Jeff Masters

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.