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June 2012

Gulf Disturbance to Meander and Bring Rains to the GOM Region

   Posted by Levi at 2:37pm on June 20, 2012

An area of low pressure is beginning to develop just southwest of Key West, Florida. The developing center remains exposed with most of the thunderstorm activity off to the east due to moderate wind shear still over the Gulf of Mexico. This should lighten a bit over the next several days, but due to the elongated shape of the area of upward motion, shear will likely be a problem for this system for the rest of its life. Despite the shear, the surface low should slowly become better defined with time over the next few days, and development of a weak tropical storm is still very possible, though it should remain weak. Heavy rains are currently affecting central and southern Florida, the Bahamas, and Cuba.

The forecast for this system is defying the natural laws and becoming more difficult as crunch time gets closer, instead of easier. The models are more split than ever this morning on the system’s future. More models have joined the GFS in trying to take the system out to the northeast over Florida into a trough along the eastern seaboard in 4-6 days, after meandering around in the central gulf for a while. I’m not ready yet to give up on the system getting caught by the Texas ridge and making it into the NW quadrant of the gulf, and the NAEFS ensemble and JMA still support that idea. The models are almost perfectly split in half on which path the system will take. Either one fits perfectly with the Allisons of 1989 and 2001 analogs. The latter in 2001 got blocked by the Texas ridge and then scooted off to the northeast into a trough over the eastern seaboard. The difference from the Allisons here is that our development is coming from farther east and may not get a chance to affect the northwest gulf if the trough catches it. Right now I am not going to sway with the models because they don’t know what they’re doing yet, as evidenced by their disagreement. What we need is for this disturbance to be tagged an invest so that the models can be initialized with the correct coordinates of the low center and then let them run. Hopefully this will happen soon. If you ever need an example of why designating invests is necessary, think of today. Specialized model runs are wonderful.

Overall, this system is not a big worry in terms of wind, as it should remain a weak system in general due to less than ideal environmental conditions, and the main story will be the rainfall that it is bringing to the gulf states. Whether the western gulf gets some will depend on whether the system actually moves in that direction instead of getting caught by the trough and moving northeast. I am still of the opinion that it will take the western road, but again, without unified computer support, the other option is on the table, and we should watch for that as well.

We shall see what happens!

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