Tropic Watch 7/27/11

By: SouthDadeFish , 12:45 AM GMT on July 28, 2011

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This blog entry will focus on newly classified Tropical Storm Don as of 21Z 7/27/11. The NHC waited for the hurricane hunters to fly in and confirm a surface circulation before classifying 90L as a tropical cyclone, even though satellite imagery was very telling. Nonetheless, the fourth tropical storm of the 2011 Atlantic Hurricane Season is here, and for the first time it appears likely we will see a direct landfall in the United States this year.


Figure 1.1: Final visible shot of Tropical Storm Don before the sun sets. Time is 23:15Z 7/27/11. Outflow is very impressive in the western semicircle and banding has been improving throughout the day.

Recon flew into Don earlier and found a central pressure of 1000mb and sustained surface winds of 35 knots. Don is a somewhat smaller storm than the norm, but has time to grow as he travels the very warm waters of the Gulf of Mexico.


Figure 2.1: This map displays the Tropical Cyclone Heat Potential (TCHP) in the Gulf of Mexico. To put it roughly, TCHP is a measure of the heat energy below the surface of the ocean that hurricanes use as fuel. Values above 80 kJ/cm^2 are often associated with rapid intensification. Don will be traversing waters near this value up until landfall, which will strongly favor intensification.

In addition to very warm waters, Don will be encountering low wind shear. Current analysis puts Don under values near 10 knots. Values under 12 knots are usually favorable for intensification. According to SHIPS forecast Don should be in a favorable environment up until landfall. Don is in a region between a retreating upper-level low pressure center in the western Gulf of Mexico and a trough over the NE Gulf of Mexico. The western ULL will continue to slide west and help ventilate Don. The trough to its north will be more of the wild card in terms of wind shear as it will begin to impose easterly winds over the storm as Don travels WNW to NW over the next two days. All in all, I see this as a favorable pattern for intensification over the next 60 hours. I do see the potential for Don to become a hurricane before landfall. My personal forecast calls for Don to reach 80 mph (category 1) before making landfall on the Texas coast.

On a side note, the U.S. has not received a landfall from a hurricane since Ike in 2008. This is very unusual to have a duration of this time frame without a hurricane landfall.

In terms of track, Tropical Storm Don is traveling around the periphery of a high pressure system located over the SE United States. This ridge should keep Don on a WNW to NW track as the ridge itself continues to build westward. Landfall should take place in about 60 hours (late Friday night-early Saturday morning). Anywhere along the western Gulf Coast from Louisiana to Northern Mexico should monitor the progress of Tropical Storm Don. However, if I had to pick the most likely landfall spot at this time, it would be the Matagorda Bay area in Texas.

At this time you should have all your hurricane supplies ready as the start of hurricane season has come and gone. This is a great time to go over your checklist and hurricane plan to make sure everything is in place. I have more information on this topic on my website.

Please stay tuned to all National Hurricane Center advisories if you live on the Western Gulf Coast as they are the authority in tropical weather.

Thanks for reading,
Fish

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3. Toddzing
1:05 AM GMT on July 28, 2011
Thanks Fish! Nice update!
Member Since: June 2, 2011 Posts: 0 Comments: 16
2. KoritheMan
12:51 AM GMT on July 28, 2011
Really enjoyed this. Thanks! Keep it up!
Member Since: March 7, 2007 Posts: 582 Comments: 20779
1. TropicalAnalystwx13
12:49 AM GMT on July 28, 2011
Thanks!
Member Since: July 6, 2010 Posts: 113 Comments: 32254

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About SouthDadeFish

I have my B.S. in atmospheric science from Florida International University and am currently in graduate school conducting hurricane research.

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