Threat lessens to U.S. from Dominican Republic disturbance 93L

Tropical disturbance 93L continues spin its wheels just inland along the eastern tip of the Dominican Republic, and is not in a hurry to go anywhere. Dominican Republic radar shows a broad circulation with a large area of rain, but the rain is not organized into low-level rain bands. Visible satellite loops show that the heavy thunderstorm activity has increased some over Hispaniola, but has decreased over nearby water areas. There is no low-level circulation apparent, and the Hurricane Hunters couldn't find one this afternoon, either. Wind shear remains about 15 knots, which is marginal for tropical storm development.

In the Dominican Republic, heavy rain has been limited to the extreme eastern end, near Punta Cana, where satellite estimates indicate up to ten inches of rain has fallen. Rainfall in the capital, Santo Domingo, has been about an inch today, according to three personal weather stations there. Additional heavy rains of 4-8 inches are likely today through Wednesday in portions of the Dominican Republic.

Haiti has thus far escaped heavy rains from 93L. I expect western Haiti will receive 1-3 inches of rain from 93L, and eastern portions may receive 3-6 inches. Heaviest rains in the Turks and Caicos islands and southeastern Bahamas should be in the 3-6 inch range. Western Puerto Rico may receive an additional 3-6 inches.


Figure 1. Forecast precipitation for the five day period ending Sunday morning 9/28/08 at 8 am EDT. A wet week with rainfall amounts up to four inches is predicted for much of the East Coast. Image credit: NOAA Hydrometeorological Prediction Center.

The track forecast
The models are now in fairly good agreement that a strong coastal storm--which could be extratropical or subtropical--will develop off the coast of North Carolina tonight. This storm will affect coastal North Carolina like a weak tropical storm would, with sustained winds of 40 mph, tide levels up to six feet above normal, and 2-3 inches of rain. As 93L is drawn northwards, the two storms will interact, and 93L will get flung northwards towards New England or the Maritime Provinces of Canada. The U.S. East Coast can expect considerable rain for the four day period beginning on Wednesday (Figure 1), but I am expecting that most of this will be due to the coastal low drawing in large amounts of tropical moisture as it tracks north-northeast up the coast. I currently give 93L a 30% chance of hitting the U.S., 60% chance of hitting Canada, and 10% chance of recurving out to sea. There is a high amount of uncertainty with this forecast.

The intensity forecast
Wind shear remains near 15 knots. The current wind shear forecast from the SHIPS model keeps the shear at 5-15 knots for the remainder of the week. The GFDL and HWRF models are less aggressive than previous runs in intensifying 93L, and I doubt the storm would hit New England or Canada as anything stronger than a 60 mph tropical storm. There is a large amount of dry air to the northwest of 93L it will have to contend with, and a good potential it may encounter some high wind shear.

Links to follow
Dominican Republic radar
Puerto Rico radar
Cape Hatteras, NC weather

The Hurricane Ike "NEXT TRUCK CHALLENGE" continues
Two wunderground members, presslord and violet312s, have announced that they will match two dollars for every dollar in contributions made to portlight.org. This charity has really made a difference in some of the hard-hit areas of Texas and Louisiana affected by Hurricane Ike neglected by the traditional relief efforts. A quote from Paul Timmons (AKA Presslord), who has helped coordinate this effort:

1.) We have reached a total of $3500 in our Next Truck Challenge....which is enough to fund another truckload of requested supplies to Bridge City and Winnie TX...will leave first of next week...Violet and I will be poorer financially...but richer in the ways that matter...y'all render me speechless...

2.) Patrap is rolling there shortly in a truck so as to arrive at first light....

3.) I don't even wanna talk about the next challenge...


If we contribute heartily to the next challenge, you'll see why Paul does not want to talk about it!


Figure 2. Portlight delivering supplies to a Winnie-Stowell Red Cross shelter. Apparently the canned cokes (not provided by Portlight) were only for lineman. The residents were only being allowed to drink water. Needless to say, the residents were very happy to see us, although there was some confusion as to whether they could actually get the supplies we delivered. Image credit: Storm Junkie.

Your contributions do make a difference, and you can read more about the effort at at stormjunkie's blog.

I'll have an update Wednesday.

Jeff Masters