As I discussed on my blog entry last Friday, the disturbance in the western Caribbean looked poised to develop. Our thinking was that it would eventually strike northeastern Mexico, possibly as a hurricane, on Wednesday evening, June 30th. When I compared our initial 5-day forecast for Tropical Depression One (which became Hurricane Alex), our 5-day track point just offshore of northeast Mexico at 6pm Wednesday, June 30th was off by only 12 miles! I’d say that forecast was extraordinary. But now the bar is raised quite high for the other 17 named storms we’ve predicted for 2010. Unfortunately, we may have our next opportunity to forecast a developing storm by the end of next week.
Over the last 3-4 model runs (which come in every 6 hours), several models are predicting that a storm will develop in the western Caribbean Sea around July 8-9. First it was the American GFS model, then the Canadian, and now the European model is predicting the same thing. All the models seem to be keying on a very strong tropical wave located in the central Tropical Atlantic that we’ve identified as “Disturbance 17″. We’ve been following this wave since it moved off the west coast of Africa 3-4 days ago. Although it’s presently lacking in any organized thunderstorms, it contains a tremendous amount of moisture and we can see evidence of rotation in the mid levels of the atmosphere. In fact, it looks very much like the disturbance which produced Alex did about two weeks ago. This tropical wave should be reaching the western Caribbean Sea around the date that the models are predicting development late next week.
A check of the current wind shear situation across the Western Atlantic reveals some quite strong winds aloft across the Gulf and northwest Caribbean (below). Much of that wind shear is due to the clockwise outflow from Alex over northeastern Mexico.
Unfortunately, the upper-level wind pattern is constantly changing out across the tropics. The image below is the latest model projection for July 9th, a little over a week from now. That’s quite a change, but not too abnormal for July. Typically, as the season progresses from June into July, wind shear across the tropics decreases significantly.
So, at least three models are now in agreement that there may be an elevated risk of tropical development in the northwest Caribbean or the southwestern Gulf of Mexico late next week. The next question to ask is where might such a developing storm track? The same models that are predicting development also provide guidance as to the steering currents that will be in place next week. As of today, indications are that the strong area of high pressure across the central U.S. which helped steer Alex westward into Mexico may not be present next week. That would mean a more northward track toward the northern Gulf Coast would be a good possibility. That’s something we certainly don’t want to see for a number of reasons. But any possible impact across the northern Gulf of Mexico is still a good a good 9-10 days away. Development is by no means certain, but it’s something we’ll be watching for very closely through the holiday weekend.
