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Gabrielle coming ashore in North Carolina

By: Dr. Jeff Masters, 2:08 PM GMT on September 09, 2007

Tropical Storm Gabrielle is strengthening slightly as it approaches North Carolina's Outer Banks this morning. Radar animations from the Morehead City radar and satellite loops both show an increase in spiral banding, and an increasing amount of heavy thunderstorm activity on the southwest side of the storm. Wind shear of 15 knots caused by strong upper-level winds from the north are slowing the intensification process, and keeping the spiral bands from wrapping around to the north side of Gabrielle's center of circulation. Due to the shear and limited amount of time left before landfall, Gabrielle should come ashore with top winds no more than 50-55 mph. The land station that should receive the highest winds from Gabrielle will probably be Cape Lookout, which had sustained winds of 23 mph with a gust to 28 mph at 9am EDT. The Diamond Shoals buoy just off of Cape Hatteras had sustained winds of 34 mph and 11-foot high seas this morning. The greatest threat from Gabrielle will probably come from tornadoes it may spawn.

Figure 1. Total precipitation from Gabrielle from the Morehead City radar. Rainfall amounts of up to five inches will affect coastal North Carolina.

Links to follow Gabrielle with
Morehead City radar
Diamond Shoals buoy (just off Cape Hatteras)
Cape Lookout C-MAN station (Coast Guard station on the coast)
Cape Hatteras current conditions
Morehead City current conditions

Gulf of Mexico disturbance (90L)
An area of disturbed weather developed in the southern Gulf of Mexico last night, just north of the Yucatan Peninsula. This region was designated "90L" by NHC. Strong upper level winds from the north are creating about 15-20 knots of wind shear over the region, and this shear is expected to remain a rather high 15-25 knots through Monday afternoon. By Monday night, the shear is expected to drop below 10 knots, which may allow some development of 90L. The system is headed west-northwest towards Texas, and residents of Texas, northern Mexico, and Louisiana should monitor this system. None of the reliable hurricane genesis models develop 90L into a tropical depression.

Tropical wave off the coast of Africa (91L)
A strong tropical wave near 10N 34W, a few hundred miles southwest of the Cape Verdes Islands off the coast of Africa, is kicking up some disorganized heavy thunderstorm activity. This disturbance was designated "91L" by NHC this morning. Last night's QuikSCAT pass showed a broad, ill-defined circulation associated with the disturbance. The disturbance is under about 10 knots of wind shear. Shear is forecast to remain below 10 knots over the disturbance over the next few days, and this system has the potential to develop as it heads west at 15 mph. Several of the computer models do develop this system, and predict that it may begin to acquire a more northwesterly track in response to a big non-tropical storm over the mid-Atlantic between Europe and the U.S. This disturbance has an environment similar to the one that spawned Hurricane Dean. The GFS-based SHIPS intensity model is forecasting that this will be a Category 1 hurricane 4-5 days from now, and I am expecting at least a tropical storm will form by then.

I'll have an update Monday 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.

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