SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Watch is in effect for... * Montserrat * Antigua * Barbuda * St. Kitts and Nevis * Anguilla * Saba * St. Eustatius * St. Maarten
SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...15.2N 51.0W ABOUT 730 MI...1170 KM E OF THE LEEWARD ISLANDS MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...W OR 280 DEGREES AT 20 MPH...31 KM/H MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES
The satellite loop this morning shows a poorly organized tropical storm at this point with one main cluster of convection in the northern semi-circle. There are a few things going on with Erika that make it a little different from Danny in terms of the environment for strengthening. The North Atlantic at this point still remains dominated by strong upper lows which create shearing environments for tropical storms to over come. Erika has bypassed the first one and seems to be in a favorable place for the time being. There is another upper low over the Domincan Republic which is creating shear there and you can see evidence of that with the remnant low of Danny producing thunderstorms over Puerto Rico that are moving west and the tops gettting blown off to the northeast. Eirka does seem to have a broader larger circulation and this may aid in helping it overcome shearing as long as it (the shrearing is not too strong). Motion appears to be west for the time being at a quick pace and that is likely to continue for awhile longer.
With regards to the future, remember this is an el-nino year and if storms can find a way to fall apart, they probably will. Models seem to want to take Erika north of the islands down the road and then vary on whether that continues or does it responding to troughing in the east and make a hard right turn. At this point it seems to me that it needs to get to at least 60 or 65 west longitude before we consider the future of this for later in the weekend and early next week.
Take a look at the gfs for Thursday afternoon and it shows what should be Erika over the Leewards as a a fairly weak system though I am always cautious with models like the GFS with how they handle the strength of tropical storms. The upper air has a strong ridge building to the north and you can also see the trough in the east.
This look should allow Erika to track along the base of that ridge toward the Bahams. If it survives (and given conditions that is a big if) it could be in a position to strengthen. Also to consider is the east coast trough and how fast it does or doesn’t lift out over the weekend and early next week.
The European aggressively builds that ridge off the southeast coast which would mean that Erika could be a threat for somebody in the Southeast and down the road however if the ridge takes longer to build and the east coast trough takes longer to lift out then the track will be much further to the right. All of this of course is in long range speculative mode and assumes among other things that Erika is an intact system when it gets there and that remains to be seen. I think the odds of Erika surviving are higher than they were for Danny but the forces in the upper atmosphere are still formidable to overcome.