**Changing weather pattern suggests a big-time tropical threat is possible in a week or so**
Paul Dorian
This forecast map by the ensemble run of the Euro features upper-level divergence in the atmosphere for next week (September 22nd to September 29th) in the (circled) region encompassing the Gulf of Mexico and Caribbean Sea. Upper-level divergence leads to compensating lower-level convergence which, in turn, enhances upward motion. This upcoming change to the overall weather pattern could result in a major tropical threat for the southern and eastern US in about 7-10 days. Map courtesy ECMWF, Weather Bell Analytics
Overview
The Atlantic Basin tropical season became more active during the past couple of weeks after a relatively quiet stretch since mid-August and it looks like the increased action will persist into October. In fact, the evolving overall weather pattern has a chance to produce a serious tropical threat in about 7 to 10 days with the likely region of interest for initial formation and intensification extending from the Caribbean Sea to the Gulf of Mexico. The movement of a tropical disturbance that propagates eastward around the global tropics will create a change in the atmosphere that will lead to enhanced upward motion later next week over the still very warm waters of the Caribbean Sea and Gulf of Mexico. This pattern change will enhance the chances for tropical storm formation and intensification in this part of the Atlantic Basin. All residents across the Gulf and US east coasts should keep an eye on any tropical storm formation next week as the potential for a powerful storm system is quite high.
This forecast map by the ensemble run of the Euro for the current week (through September 21st) features upper-level convergence in the atmosphere in the (circled) region encompassing the Gulf of Mexico and Caribbean Sea. Upper-level convergence leads to compensating lower-level divergence which acts as an inhibitor to large-scale upward motion and is acting as a "cap" on tropical activity....that "capping lid" comes off later next week. Map courtesy ECMWF, Weather Bell Analytics
Details
Hurricane Francine made landfall last week in central Louisiana and a second tropical system (unnamed) pushed into the Carolinas on Monday producing some serious flooding in that part of the eastern US. Farther east, Tropical Depression Gordon is slowly churning over the eastern Atlantic Ocean. While Gordon has a good chance of strengthening into a tropical storm, it is likely to not impact any land mass in the near-term (or ever) as it’ll likely stay out over the open waters of the eastern Atlantic.
The 00Z GEM model run does indeed suggest a serious tropical threat will exist in the Gulf of Mexico by the middle or latter parts of next week. Map courtesy Canadian Met Centre, tropicaltidbits.com
Looking ahead, the evolving weather pattern may actually become much more conducive to tropical storm formation/intensification in the Caribbean Sea and Gulf of Mexico as upper-level divergence and surface-level convergence become more pronounced. Convergence at the surface level and divergence aloft would enhance upward motion in these areas, potentially leading first to strong thunderstorm development, and ultimately, to the development of a tropical storm. Given the still very warm sea surface temperatures and the likelihood of significant upward motion, the potential is quite high for the development of a powerful tropical system in 7-10 days.
The change to this upper-level pattern with the shifting in position of a tropical disturbance kicks into gear later next week with increasing upward motion specifically destined for the Caribbean Sea/Gulf of Mexico. In other words, the time period of 7-10 days from now could very well feature a powerful tropical system somewhere over the Caribbean Sea/Gulf of Mexico region which could ultimately become a serious threat to the Gulf coast and eastern US…stay tuned…a wide area of the southern and eastern US could be impacted given this evolving weather pattern.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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