Dorian to Brush Northern Caribbean Islands Next Week

By Alex Sosnowski, Expert Senior Meteorologist

July 26,2013; 9:32PM,EDT

 

 

 

Dorian is forecast to bring tropical storm conditions to some northern Caribbean islands next week, but the storm is unlikely to become a major hurricane.
While the system will enter warmer waters this weekend, it will approach an area of increasingly disruptive west to southwest winds in the middle layers of the atmosphere.
A slightly north of west path is forecast with Dorian through this weekend into early next week with the system being pushed along by the trade winds near the sea surface.

These low-level steering winds will guide the center of Dorian north of the Leeward Islands Sunday and nearby to the north of Puerto Rico Monday.
If the system holds together but remains weak, it would pass somewhere between Hispaniola and the Turks and Caicos during the middle of next week.
Conditions in these islands will depend upon the exact path and strength of Dorian.
There is a possibility of gusty, drenching squalls, even if the center of the system just misses or weakens.
Many of the islands of the northern Caribbean have received above-average rainfall since April. San Juan, P.R., has received nearly 44 inches of rain since April 1. A tropical disturbance brought nearly 10 inches of rain to the area recently, during July 17-18, so a system bringing a dose of heavy rainfall would bring an elevated risk of flash flooding and mudslides.
According to AccuWeather.com Hurricane Expert Bob Smerbeck, "During later this weekend into next week, conditions favoring further development of Dorian will be warmer water, but conditions working against development will be increasing wind shear, frictional effects of the larger islands and fast movement of the system in general."
The interaction of these conditions will likely keep the system in check in terms of strength and could even lead to weakening in the long term.
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At 8:00 a.m. EDT Wednesday, the system may have already been a tropical storm. Enhanced satellite images during the morning hours indicated a concentrated area of thunderstorms with some rotation. At 10:30 a.m. EDT Wednesday, winds were officially estimated to be sustained at 50 mph near the center, and the system was named Dorian.
At 5:00 a.m. EDT Thursday, sustained winds were estimated to be 60 mph.
At 11:00 p.m. EDT Thursday, sustained winds decreased and were estimated to be 50 mph.

Official investigation by the the National Oceanic and Atmospheric Administration (NOAA) and the National Hurricane Center (NHC) will continue. Sustained winds must reach 74 mph for the system to be classified as a hurricane. NHC and local governments are responsible for issuing official watches and warnings.

The path and impact of Dorian next week will depend on the strength of the tropical system itself and other weather systems surrounding it. Currently, Dorian is moving swiftly along to the west-northwest at around 20 mph.

Later next week, there are several scenarios with Dorian.
It could be scooped up by the back side of high pressure near Bermuda over the Atlantic Ocean. In this scenario, implying a well-organized tropical storm or hurricane, the feature could then travel along or off the East coast of the United States.
Another scenario, implying a minimal system or one struggling to survive, allows Dorian to miss the "right turn lane" and continue west-northwestward brushing northern shores of Cuba.
In the middle of this wide window, but not necessarily the most likely third scenario is for the system to reach the southeastern U.S. with a pocket of drenching rainfall, around the first weekend of August.
However, it appears unlikely the system will gather enough conditions to become a major hurricane. And, it is possible, allowing for some fluctuation in strength, it could lose much of its organization before reaching U.S. coastal waters.
In addition to potential fringe-effect impact in the Lesser and Greater Antilles, people in the Bahamas and the Turks and Caicos should closely monitor the path and strength of Dorian. These areas are currently in a higher risk for the storm to pass very close by next week.