The southeast U.S. to get a subtropical soaking; Bigger problems may arise by mid-month

   Posted by Levi at 8:29am on October 7, 2011

Thunderstorm activity is on the increase near and east of Florida as an upper trough digs into the eastern Gulf of Mexico. This is the catalyst that we talked about yesterday that would be needed to spark stormy weather that could lead to subtropical development early next week. The air is still very dry in this area, and won’t magically become a sauna, but gradually these thunderstorms will throw enough moisture into the air that some feedback should be able to occur and consolidate into an area of low pressure just east of Florida. The ECMWF and CMC are still hanging on tight to their idea of the low forming in the eastern Gulf of Mexico, but I continue to favor the GFS solution for being farther east, to the east of the trough axis where the dynamics are more favorable. Even if we get weak low pressure to stack with the upper trough in the Gulf of Mexico initially, a secondary low should form to the east and become dominant as it phases northward into the southeastern states. Even farther up the eastern seaboard may see some interesting weather if the system waits long enough so that it can phase with the trough coming out of the plains in 6-7 days.

Overall, several days of very blustery weather with heavy rains, up to several inches, and gale-force winds in places, is in store for Florida and surrounding areas this weekend and into next week. This won’t be anything particularly dangerous, but we might get a named subtropical system out of this mess that makes life interesting for a few days. This development fits perfectly into the pattern that we’ve been discussing, where high pressure builds strongly over the eastern United States while the MJO is shifting back into our area of the world, supporting mischief.

This is far from the last we will hear from the tropics in this pattern though. As I have spoken of, as soon as our subtropical entity gets absorbed into the east coast trough, it shifts east and allows the eastern U.S. to get charged up with high pressure a second time, focusing convergence down in the Caribbean again. With the MJO becoming fully focused in our area of the world as the two eastern Pacific storms move eastward, the monsoonal circulation may have a chance to ignite on the Caribbean side in 8-12 days, allowing a storm of more truly tropical nature to develop and move northward towards the southeastern United States, just as I have been warning about for so long in this pattern. The GFS and ECMWF are both starting to consistently show this 2nd system developing in 8-10 days. I show in the video how the monsoon circulation makes a massive leap eastward during the next week, setting this up.

We shall see what happens!

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