GOM Development Possible Late Next Week – Ghost of Allison?

   Posted by Levi at 2:47pm on June 12, 2012

The developing pattern continues to look favorable for tropical development in the Gulf of Mexico later next week as the MJO moves into phase 1, lending upward motion support to the western Atlantic, which is usually necessary for getting a June development. The ridging pattern over the Great Lakes also supports piling up of air to the south of the United States, which leads to upward motion and lowering of pressures in the Gulf of Mexico, and this is being echoed by all of the models. What the models are not seeing consistently yet is actual development of a storm, with only last night’s CMC currently showing one, but we are still 7-12 days away. The models will likely become more consistent one way or another once the MJO stops racing across the Pacific and settles down in phase 1, which it is forecasted to do.

Figure 1. 0z CMC 240-hour forecast

The pattern looks very similar to when Allison formed in June 1989, as well as the more recent Allison in June 2001. Here are their tracks:

Figure 2. The tracks of the Allisons of 1989 and 2001.

Both storms were very similar, both moving quickly into Texas and then getting blocked, causing flooding. In the video I show the pattern that led to the blocking of both storms and compare it to the similar ensemble forecasts for next week, and the retrogressive pattern that occurred during both Allisons is supported by the currently very progressive MJO. This is a pattern that favors development more than usual for June standards, but even further than that, we may have to watch for the ghost of Allison with this setup, where a quick-hitting storm tries to develop in the gulf, move inland, and then potentially get blocked, either over land or water, causing a heavy rain event for the gulf coast.

We shall see what happens!

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