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August 2013

Development Possible in Bay of Campeche – Eastern Atlantic Still on Track to Get Active

   Posted by Levi at 8:34pm on August 24, 2013

A couple areas of disturbed weather have developed in the Caribbean and Gulf of Mexico over the last day or so, in response to the unstable pattern in the region. A surface trough developed in the northern Gulf of Mexico a couple days ago, and is bringing rain to the central gulf coast. As I mentioned yesterday on Facebook, although mid-level rotation has been evident, low-level convergence is focused southwest of the main area of thunderstorms, which is keeping the feature decoupled, and development appears unlikely as it moves generally westward along the north gulf coast over the next couple of days. The feature may bring some much-needed rain to coastal Texas.

To the south, a vigorous tropical wave moved into the Yucatan Peninsula last night, and an area of low pressure has developed near the mid-point of the wave axis over land today, designated Invest 95L by the NHC. There appears to be a closed circulation, which may emerge over the extreme southern Bay of Campeche by tomorrow. Given its excellent structure already, development of a tropical depression or storm may ensue immediately after moving over the water if it has enough room away from land. A deep-layer ridge to the north will keep 95L on a generally west or WNW track, and very little time will be spent over water before moving back into Mexico. Thus, the system is expected to be mainly a rainfall threat for Mexico.

Looking to the east, the tropical Atlantic remains quiet for the moment. The ITCZ is much farther north than normal, and low-level wind patterns are very favorable for the development of tropical waves. What is lacking right now is vertical motion to generate thunderstorms. The MJO is expected to move into phase 1 by most of the models during the next week or two, and this should provide a “boost” to the eastern Atlantic beginning by the end of this month and the beginning of September. Once the air finally becomes unstable enough, we should start to see tropical storms forming from tropical waves and ITCZ lows.

A pattern like this can accelerate activity rapidly. If the missing ingredient is added, we could quickly go from no storms at all to multiple storms simultaneously. The global models are starting to see this likely uptick in activity, with the GFS, CMC, and ECMWF now all hinting at development east of the Caribbean in the 6-10 day time frame. Below is the ECMWF forecast for Day 10, showing one or two disturbances trying to develop. This is still in the long-range, but this is the first time this year that the reliable ECMWF has shown tropical development in the central-eastern Atlantic. Take this as another sign that the peak of the season is here, and it won’t be long before our first hurricane forms.

It’s starting to get pretty late for our first hurricane, but in a pattern like we have this year, once the first one forms, it may uncork a burst of storms that doesn’t stop for multiple weeks. Four named storms typically form during the month of September. I think we are likely to see a more active than normal September this year. Be prepared in case any of these storms come your way.