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Atlantic Tropical Weather Update 8/28/08


The next few days should prove to be very interesting for the tropical Atlantic. Tropical Storm Gustav was really weakened quite a bit by the high terrain of Haiti. His center floated considerably further south than most realized yesterday. This morning, that distancing has worked in Gustav’s favor. He has begun restrengthening. His vitals:

17.8N, 75.6W is where his center lies. That’s just off the east coast of Jamaica and 1S of where he was yesterday morning. This morning, his maximum sustained winds have increased back to 70mph. He is moving WSW @ 5mph. His central pressure is back down to 988mb.

Model output is in good agreement regarding the next day or two’s motion. Gustav should continue moving W to WNW, impacting Jamaica. The official track forecast has him moving just south of Jamaica, but he could move directly over the island instead. After that, his motion should be steady northwestward. Model solutions differ on his exact path in the region of Cuba still. He could make landfall over the western portion of the country or pass between the island and the Yucutan. That hasn’t changed much over the past 2-3 days.

The 4-5 day forecast is steadily moving closer to U.S. shores. Last night, the official track forecast wasn’t pretty. It indicated a landfall on Louisiana’s southern coast, southwest of New Orleans as a potential major hurricane. This morning, the official track forecast has been moved to the west slightly. It looks like Gustav could make landfall somewhere between Lake Charles, LA and Abbeville, LA. The envelope of model solutions has Gustav making landfall somewhere along the coast of Louisiana and it is this envelope that folks should be paying attention to. The intensity forecast has Gustav strengthening to at least Category 3 status by the time it is in the central Gulf of Mexico. It is likely, under current forecast projections, to be at that strength when he eventually makes landfall. As such, hurricane and tropical storm force winds will extend quite a ways from the center of the storm. The east and north sides of the storm will be especially dangerous. So landfall is currently projected to occur sometime on Tuesday. That could change, of course.

Activity is picking up somewhat across the Atlantic basin. Tropical Depression Eight has formed from the disturbance known as Invest-95. It is expected to reach Tropical Storm strength later today as it continues to get organized. If it does so, it would be designated Tropical Storm Hanna. This storm could strengthen further to hurricane status by Sunday. It’s current location is centered at 19.8N, 57.9W. It is moving WNW @ 4mph, has maximum sustained winds of 35mph, and its lowest pressure is estimated to be 1004mb. It is forecasted to turn more towards the west in the 4-5 day time range, though that’s pretty uncertain right now. If it does so, it would be moving west toward the Bahamas and Florida. We’ll see what happens.

There are three other disturbances scattered across the Atlantic: one in Gulf and one west of the Cape Verde Islands that have a 20% chance of developing within the next day. The third is just emerging off the west coast of Africa and has a 20-50% chance of development.


[Update 2:25P MDT]:

Gustav has nearly strengthened back to hurricane status, as expected. Based on hurricane hunter information from this morning, here are Gustav’s latest set of vitals:

Located at 17.9N, 76.2W; maximum sustained winds of 70mph (just beneath Category 1 hurricane strength); moving W @ 4mph; minimum central pressure of 983mb. Gustav looks a little more impressive in satellite imagery this afternoon. Outflow is most prominent on the southern half of the storm.

Gustav’s center is coming very close to Jamaica, which remains under a hurricane warning. The official track forecast has Gustav hugging Jamaica’s southern coast, or possibly moving just inland. Once clear of Jamaica, Gustav has a straight shot across an open Caribbean Sea that is plenty warm (sea surface temperatures in excess of 29C the whole way). Thereafter, Gustav’s center could pass over western Cuba or move through relatively unimpeded, but that’s still somewhat uncertain at this time.

The news of Gustav’s likely path toward the U.S. coast has definitely hit the major corporate media, as well it should have. The model suite still shows a likely Louisiana landfall, but uncertainty remains high to the forecast length involved.

Alternatively, the eighth tropical storm of the season has formed. Tropical Storm Hanna is centered on 20.7N, 60.1W; she has 40mph sustained winds; she is moving WNW @ 12mph; her minimum central pressure is about 1003mb. As I discussed earlier, she is forecasted to move more or less northwestward for a couple of days before bending more toward the west around next Monday. She could strengthen to a Category 1 storm by that time.

There has also been a change with Invest-96, the disturbance that is in the Gulf of Mexico. I-96 is very close to land and should move ashore within the next day, cutting off any chance of development. The primary threat from this system will be locally heavy rains for portions of Mexico.


I’m going to interject a little politics into this post. I hadn’t considered this facet of Gustav’s future, but if he reaches Category 3 strength and makes landfall in Louisiana Monday, the same night President Bush is scheduled to address the RNC, it will be a stark reminder that Hurricane Katrina made landfall only 3 years ago. I hardly think that Republicans want the public to be reminded that they failed to respond to that disastrous event. Life is rich with irony, isn’t it?


[Update 6:25P]:

There is an important factor in Tropical Storm Gustav’s future that needs to be relayed to as much of the Gulf Coast public as possible, as soon as possible: a portion of the Gulf Stream Loop Current could break off the Stream and act as a huge reservoir of energy for any storms that cross through the Gulf north and northwest of Cuba.  This exact thing occurred back in 2005 and helped Katrina and Rita explode into Category 5 storms.  This map from the Naval Research Laboratory shows that a large pool of very warm water lies just of the northwest coast of Cuba right now.  Tropical Storm Gustav is likely to overrun a similar pool once he clears Jamaica later tonight.  About the only thing working in the Gulf Coast’s favor is a cooler pool of water is currently located between the Loop Current and the shore.  That should act to limit the intensity of what will be Hurricane Gustav if he makes it to the area early next week.

Interestingly, a good-sized volume of water that exited the Gulf of Mexico east of Florida has similar characteristics to those in the Gulf.  If Tropical Storm Hanna overruns that region, expect her to strengthen very quickly as well.


2 thoughts on “Atlantic Tropical Weather Update 8/28/08

  1. will any of these tropical storms or hurricans effect the Texas coast near Corpus Christi

  2. rachel – right now it’s hard to say with any confidence. It is unlikely given current conditions. By the time Gutav moves into the Gulf, we should have a better idea of his potential track and where he is likely to impact the coast.

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