Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.
By: Levi32 , 4:34 PM GMT on June 12, 2009
Tropical Tidbit from 12:30pm EDT June 12, 2009:
An upper trough centered over eastern Cuba and Jamaica has begun to make its move north and east preparing to lift out of the area. Along with it the area of showers and thunderstorms within the diffluent flow on the trough's east side has shifted east as well, bringing rain mostly to Hispaniola today, and giving Cuba and Jamaica a dry spell. This break will be short-lived though, as the tail-end of the upper trough is expected to split into a cut-off low in the NW Caribbean today as the main trough moves out, which will shift the diffluent zone back to the west over Jamaica and eastern Cuba tonight, once again bringing rain to the area. During the weekend the upper low will back away towards the SW over Guatemala, bringing showers and thunderstorms with it. This will allow an upper-level high pressure system to build over the western Caribbean in 48-72 hours.
At the surface this morning we still have a weak trough in the western Caribbean that extends from Panama to up west of Jamaica. The convection that was associated with it has all but disappeared today as it loses the support of the upper-level forcing provided by the upper trough. The area remains under 30 knots of wind shear. None of the global models are forecasting a closed low to form anymore, and it's starting to look like the ECMWF is going to win out in having the best solution for this system.
The surface trough will slowly drift northwest over the weekend as the cut-off upper low moves out of the way and allows wind shear to lower over the region. The ULL (upper-level low) will likely amplify the trough and enhance shower activity along its axis, but I do not expect any significant development. Regardless, I will keep an eye on the system early next week as sneaky things can always happen when an upper high builds over top with an ULL backing away. 1-3 inches of rain is expected for Honduras, Nicaragua, Cuba, and Hispaniola over the next 3 days, with a pocket of 3-6 inch amounts expected for Jamaica and the Caymans.
Elsewhere....a tropical wave along 58W with strong low-level turning will bring moisture through the Antilles Islands by tomorrow. The windwards should only get isolated showers with most of the moisture staying confined to Trinidad and Tobago. This wave is currently no threat to develop but should be watched in 3-4 days as it enters the western Caribbean and a more favorable environment.
In 4-7 days the GFS is forecasting a front to drop down from the NE US and drape itself across North Carolina and out into the Atlantic. The GFS forms a low along the tail-end of this front on the back-side of the upper trough that will be moving through to the north. I will keep an eye on this area next week.
So are our chances for a June named storm pretty much over? The answer is no. It will definitely seem unlikely in about a week if nothing has developed and the subtropical jet comes back down into the Caribbean, but it doesn't end there. The MJO is entering phase 8, which centers upward motion over the western Atlantic. The ECMWF/GFS 8-10 day comparison shows the mean upper high to continue to build over the north gulf coast and remain in that area. What this says to us is to watch under the high (by under I mean south of). Sure enough the GFS long-range has been consistently forecasting lots of moisture over the western Caribbean, Central America, and the southern Gulf of Mexico in the 10-15 day period. This is the area to watch for mischief during the last 2 weeks of June.
We shall see what happens!
GFS Forecasted Total Precipitation ending 2am local time June 15th:
Caribbean Visible Satellite: (click image for loop)
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.