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June 2012

Atlantic quiet for now; Watching for GOM Development June 18th-25th

   Posted by Levi at 7:42pm on June 8, 2012

The Atlantic is currently quiet, with the only feature of interest being an old frontal boundary over the northern Gulf of Mexico that poses no significant threat for tropical development over the next few days, though it will bring rainfall to the gulf coast. As discussed back when Beryl was making landfall in Florida, the first half of June here is quiet, and will continue to be so through at least the 15th.

However, the signs for the next round of tropical activity have already been showing themselves, as the MJO is unanimously forecasted to come back into phases 8 and 1 in 10-15 days, bringing upward motion back to the Atlantic. At the same time, the models are forecasting anomalous ridging to develop over the Great Lakes and Hudson Bay region, and the fact that these anomalies are that far north means we have to watch to the south of the ridge for tropical activity in the Gulf of Mexico and northwest Caribbean. All of the ensemble means show a significant lowering of pressures in the region after Day 10, with about half of the GFS ensemble members and CMC ensemble members all showing tropical development of some kind during the 10-15 day period.

The CPC analogs based off of the GFS ensemble Day 11 forecast are also very interesting. Looking at the top 3:

1) June 23rd, 1989 – Allison developed the next day and moved into Texas.

2) June 2th, 2005 – Arlene developed 6 days later and moved into Florida as a near-hurricane.

3) June 27th, 1975 – Amy developed in the Bahamas and moved up towards North Carolina.

So one can see that in very similar patterns to the one we are headed into, development has occurred multiple times. We always have to watch to the south of big ridges over the Great Lakes, as it usually means trouble of some kind. Notice that when Alberto and Beryl formed, a blocking ridge was found to their north over New England and the NW Atlantic, but here the ridge is shifting west, implying that the development region should shift west with it, and the Gulf of Mexico will have a shot at early-season development. Details on any potential development here will remain vague for a while since it is still a long ways out, but the period of June 18th-25th will likely see a significant uptick in activity in the northwest Caribbean and Gulf of Mexico.

We shall see what happens!