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Atlantic Tropical Weather Update 8/31/08

Hurricane Gustav came off the western portion of Cuba last night as a Category 4 hurricane and maintained that strength while continuing northwest. It appears that interaction with the landmass caused Gustav to weaken slightly since then. As of this morning, Gustav has weakened to a still very dangerous Category 3 storm. Starting with his vitals:

Center located at 25.3N, 86.0W; maximum sustained winds of 120mph; moving NW @ 17mph; minimum pressure of 960mb, about 20mb higher than the last time I looked near 12A MDT.

Gustav’s impressive satellite signature yesterday has degraded so far today. There is no longer a clear eye portion of the storm. Also, the convection and outflow isn’t as symmetric as it was late last night. The strongest convection looks to be confined to the southwestern portion of the storm.

What’s next for Gustav? He is still heading straight for the northern Gulf coast. As the hours tick away, his most likely landfall site is being forecasted with more confidence. Somewhat surprisingly, that location remains southern Louisiana, perhaps a bit to the east of where I thought he would strike the past two days. It looks more likely that the site will be close to New Iberia, LA. Models are forecasting a slight re-increase of strength back to Category 4 status while Gustav is still over the Gulf. Prior to landfall, his strength should begin slowly decreasing and continue to do so after landfall. Landfall is expected to occur during the day on Monday, currently sometime after 8A CDT. Due to the influence of the ridge of high pressure over the eastern U.S., his forward speed should decrease and the possibility of him stalling over Louisiana or Texas remains high.

Storm surge from Gustav is expected all along the northern Gulf coast. A maximum of 12-15 feet of storm surge is possible near the mouth of the Mississippi River and east of New Orleans. The height of surge east and west of this region decreases from there, with up to 12 feet forecasted a good distance away from the River, out toward Abbeville to the west and Biloxi, MS to the east. Combined with rain from convective bands, flooding then becomes a major risk from this storm across a very wide area. The initial storm surge and winds will weaken infrastructure and a stalled storm will only add to the challenges facing those who live and those who will help clean up in the region. Based on Gustav’s current projected path and expected effects, I don’t think the situation looks good for the New Orleans area. Damage from wind and flooding should occur once again. It is obviously too early to tell just how extensive that damage will be, which means that officials along the Gulf coast should be congratulated on acting promptly to move residents away from the area.

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Atlantic Tropical Weather Update 8/30/08

Hurricane Gustav has passed over the deep, very warm waters between Jamaica and Cuba. In doing so, he rapidly strengthened overnight from a Category 1 hurricane to a Category 3 storm this morning, making him the second major hurricane of the 2008 Atlantic season. Bertha was the other major hurricane, but remained well out to sea her entire lifetime. Gustav’s vitals as of 8:30A MDT:

Center located at 20.8N, 81.6W; maximum sustained winds of 120mph; moving NW @ 11mph; minimum pressure is down all the way to 955mb, which is 33mb less than the reading yesterday. That is quite the rapid intensification. In fact, since the pressure has continued to drop steadily this morning, expect Gustav to strengthen even further today before eye-wall replacement cycles, a slightly cooler pool of water and the island of Cuba work to weaken him somewhat.

Gustav should still make landfall over Cuba later tonight as a Category 3 storm. A solid eye-wall did develop overnight. Gustav has an impressive outflowing cloud shield. Hurricane force winds were found on the northeast quadrant on an earlier hurricane hunter flight. As they get going again today, a clearer picture of where they are found will be available. Tropical Storm force winds extend all the way to Cuba, a decent distance from the storm’s center. Western Cuba is under a Hurricane Warning today.

Model solutions have come to closer agreement as of today. There is a much narrower band encompassing the solutions through the Gulf of Mexico, which Gustav will enter 12-24 hours from now. While Gustav crosses the central Gulf, he is still forecasted to overrun the Gulf Loop Current’s warmest stretch. The model intensity forecast has him strengthening to a Category 4 hurricane during this time, but I wouldn’t be surprised to see him go all the way to a Category 5. After that, there is very good agreement about the likely landfall location: the middle of the Louisiana coast. He should make landfall between Morgan City and Lake Charles. The timing is coming into better focus. The suite of models are also in pretty good agreement that the landfall could occur Monday night.

Post-landfall may not offer a better story than during landfall. Due to the strength and orientation of the ridge that will remain over the eastern U.S., Gustav could stall over Louisiana. We’ve already dealt with one slow moving storm: Fay dropped incredible amounts of rainfall over Florida just a week or so ago. Gustav shouldn’t dump quite that much rain, but the longer he lingers, the more flooding far inland will be a concern. New Orleans residents are smartly already evacuating. I’m sure other Gulf coast residents will follow similar measures throughout the next two days.

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Atlantic Tropical Weather Update 8/29/08

I would like to start by acknowledging the events of 3 years ago.  Hurricane Katrina by this point in the day, currently 9A MDT, had made landfall and was in the midst of catastrophically damaging one of America’s major cities.  That city still hasn’t recovered from the storm.  Neither have the areas along the Gulf coast that were similarly affected.  The Army Corps of Engineers has since worked to repair the levee system and even announced that they were rebuilt to withstand another Category 3 storm.  Let’s hope the residents of New Orleans don’t have to find out whether that’s true or not.  My opinion is that the levees aren’t strong enough.  It will require elected officials that actually care about their fellow citizens to take serious action in the Gulf coast region.  It will require yet more time and money to prepare the region for the next major storm.

We’re edging closer to the time when Gustav could directly impact the U.S.  He slowly made his way across Jamaica overnight and now has nothing but warm oceans and marginally unfavorable wind shear to contend with.  Let’s begin by looking at his vitals:

Center located at 18.6N, 78.8W; maximum sustained winds of 65mph; moving WNW @ 8mph; minimum pressure of 988mb.

Gustav should strengthen to hurricane status sometime today.  There were readings yesterday even while over Jamaica that Gustav could have wobbled around that threshold, but the NHC decided to stick with a Tropical Storm designation.  Regardless, Gustav should assume a more northwesterly heading by the end of the day, takind aim at Cuba’s west coast tomorrow afternoon/evening as a Category 2 storm.  By Sunday morning, Gustav should enter the Gulf of Mexico, regardless of whether he makes landfall over Cuba or not.  Further strengthening is forecasted throughout this time frame and by the time we wake up Sunday, Gustav could be a Category 3 storm (major hurricane).  By Monday morning, Gustav should be taking aim at a smaller portion of the Gulf Coast.  It really won’t be apparent where he should make landfall until Sunday/Monday.

Gustav’s track should take him just to the right of the warmest portion of the large extra-warm pool of water that is WNW of Jamaica, the Gulf Loop Current.  Despite missing the warmest portion of the pool, Gustav could quickly strengthen over the next 24 hours.  The official track forecast would put Gustav over another very warm pool currently located northwest of Cuba.  That could be the time when we see the most explosive growth of this system, if such a thing does occur.  After passing this pool, there shouldn’t be any other factos that drastically alter Gustav’s strength.  He will of course experience eye-wall replacement cycles, which will cause his intensity to oscillate.  The current official forecast calls for Gustav to make landfall along the Louisiana coast west of the Mississippi River as a Category 3.  But do not be surprised if he is stronger at landfall.  Also, the exact landing site is quite frankly irrelevant.  A storm of this magnitude will affect a large area.

In fact, Louisiana has already declared a state of emergency.  A handful of residents along the Gulf coast have announced that they’re evacuating now, no doubt remembering the chaos of evacuating ahead of Katrina, when it was too late to do so.  If you live along the coast or know someone who does, make sure you’re aware of the development of this system.  It has the potential for significant to catastrophic damage.  Stock up on food, water and other emergency supplies now.

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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.

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