Invest 91L is looking better, probably a TD within 18 hrs. Lots of rain for FL

Invest 91L which is located over the central Gulf of Mexico this morning has become a little better organized over the last 6 hours or so. This organization is supported by buoys in the area which are reporting wind gusts to 40 mph early this morning. Additionally, satellite loops show some deep convection firing on the eastern side of this system as dry air across the western Gulf of Mexico has all but squashed thunderstorm development on the western quadrant of this system. As I have mentioned previously, I expect this to be an eastern weighted storm and I have no changes in that thinking.

So, between today and Thursday night, which is when I expect this system to track inland into Florida, I expect very slow development due to a combination of dry air and continuing 20 to 30 knots of shear. I do think that there is a fairly good chance that Invest 91-L will become either our first tropical depression of the season or our first tropical storm of the season. As for a track, I think we will see Invest 91-L track northward today before turning north-northeast and then northeastward as we get into Thursday. Based on this, I think we will see this system come ashore somewhere between Cedar Key and Apalachee Bay in northwestern Florida as at most a 40 to 45 mph tropical storm on Thursday night. From there, this system will likely go extratropical fairly quickly and track northeastward to near eastern North Carolina by Friday evening and then to near Cape Cod and eastern Maine during Saturday.

Rainfall and tornadoes will be the biggest threats from this system, whether it becomes a tropical storm or not. Additional rainfall amounts of 3 to 6 inches can be expected across the entire Florida Peninsula from today through Friday morning. Heavy rainfall with amounts of 2 to 4 inches can be expected from late Thursday to Saturday from eastern South Carolina and eastern North Carolina northward to southern New England.

The tornado and waterspout threat will increase as we get into this afternoon and tonight across the Big Bend area of Florida as well as the west coast of Florida, including Tampa and Fort Myers. This tornado threat will overspread the rest of the Florida Peninsula on Thursday with the tornado threat continuing through Thursday night and into Friday morning.

I will be monitoring Invest 91-L closely and will keep you all updated on the latest.

Elsewhere in the tropical Atlantic, I am starting to take notice of a tropical wave with an associated low pressure system located well east of the Windward Islands out near 40 West Longitude. The reason it has gotten my attention is because of the strong vorticity associated with it (amount of spin) and also it is embedded within an area of 10 to at most 20 knots of shear. This tropical disturbance is tracking to the west-northwest and will gradually turn more northwestward over the next day or so. At this point, it is expected to track just north of the islands of Anguilla and St. Martin by Sunday and the further north it gets in latitude the less chance it has to develop due to stronger wind shear values to this disturbance’s north.

At this point, this disturbance is only an item to keep an eye on and I do not expect any significant development from it. It will, however, increase the rainfall chances across the Leeward Islands and the Virgin Islands starting Saturday night and continuing into Sunday. Additionally, rough seas are possible across the Virgin Islands and the Leeward Islands this weekend due to the proximity of this disturbance.