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Atlantic Tropical Weather Update 9/6/08

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[Update 10:45P MDT]:

Just a quick update tonight.  Hurricane Ike’s extended track continues to move further to the south and west and the large-scale flow develops.  Ike is now forecasted to cross over most of Florida from east to west, then emerge over the Gulf of Mexico on Tuesday afternoon as a much weaker hurricane.  Then, the official track takes Ike through the central Gulf.  Extrapolating the track takes Ike quite a bit further west than today’s earlier official forecasts.  This very dangerous storm is going to cause a lot of damage over Cuba for nearly three days, then is likely to threaten some portion of the northern Gulf coast.

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[Update 3P MDT]:

Tropical Storm Hanna is racing across the eastern seaboard, Hurricane Ike has reintensified and is threatening the Bahamas and Cuba, and Tropical Depression Josephine has disorganized to a mere disturbance.

Tropical Storm Hanna’s center is located at 38.5N, 75.8W; has maximum sustained winds of 50mph; is moving quickly towards the NE @ 27mph!; and has a minimum pressure of 994mb. Lots of rain and those strong winds have affected the Carolinas, Virginia this morning and now is impacting Maryland, Pennsylvania and New Jersey. Later tonight and tomorrow morning, New York and the other northeastern states will see Hanna race through. Hanna looks likely to move back off into the Atlantic tomorrow before striking some Canadian provinces through Monday morning. As has been predicted for some time, Hanna will continue racing off towards the east across the Atlantic. By Thursday, Hanna should be between Ireland and Iceland in the north Atlantic. Her tropical characteristics should have been long exhausted by then and will resemble another mid-latitude storm like Gustav did after getting caught up in the westerlies.

Hurricane Ike has reintensified today as the shear affecting him the past day or so has finally been left behind as he moves toward the west across the Atlantic. His center is currently located at 21.4N, 69.7W; has maximum sustained winds back up to 135mph (making Ike a Category 4 storm again); is moving WSW @ 14mph; and his central pressure is back down to 949mb. Ike is currently moving south of the region where Hanna stalled, and thus could avoid the cooler waters she left behind. The WSW motion should continue over the next 24-36 hours as the ridge to Ike’s north continues to direct him.

Which brings us to Monday morning. Hurricane Ike is now forecasted to make landfall along Cuba’s north coast as a Category 4 storm. If this comes to pass, and Ike moves across Cuba as the most recent official forecast indicates, Hurricane Cuba will weaken back to a Category 1 storm before reemerging over the Gulf of Mexico sometime Tuesday afternoon. The majority of the model solutions keep Ike on the northern half of Cuba during his transit. One outlier moves Ike directly across southern Cuba and places Ike in the northern Caribbean Sea in 36 hours. That outlier has done a pretty good job in recent days in correctly forecasting Ike’s continued WSW motion. So it’s not out of the question that Ike could indeed take this path.

The official track forecast places Ike on a direct path toward the northern Gulf coast between Tuesday afternoon and Thursday afternoon. The official intensity forecast calls for Ike to restrengthen to Category 3 strength by Thursday afternoon. The Gulf is still plenty warm and shear isn’t expected to be much of a problem during the forecast period. If the official forecast ends up being correct, extrapolating Ike’s motion from Thursday afternoon places it at the Gulf coast next Saturday. Ike’s potential landfall point is way too far out in the future to identify at this time, so Gulf coast residents need to keep appraised of Ike’s progress. Many residents could unfortunately be required to evacuate again. I hope Gustav’s relative lack of impact (compared to the 2005 storms) on the Gulf coast hasn’t placed too strong a sense of invincibility on the parts of Gulf coast residents. While we don’t know where Ike will land yet, he hold too much potential for destruction to ignore.

[Update 9A MDT]:

And Hurricane Ike’s forecast has changed again this morning as new model runs have become available. Let’s start with the most up-to-date location information:

Center located at 21.9N, 68.8W; maximum sustained winds of 110mph, making Ike a strong Category 2 storm; still moving WSW @ 16mph; minimum pressure of 960mb, down slightly from earlier this morning.

Hurricane Ike has been battling the same northeasterly shear that ended up wrecking Hurricane Hanna. We’ll see if he has any better luck at sustaining himself. As a result of the new fixes and large-scale model information, Hurricane Ike’s anticipated trajectory and intensities have changed this morning also. He is currently expected to regain major hurricane status by this time tomorrow as the upper-level feature weakening him is finally left behind. His track should now take him over central Cuba late tomorrow night as a Category 3 storm as he bottoms out his path and begins moving WNW again. This is likely to mean that Ike will transit most of Cuba and re-emerge over the Gulf of Mexico as a weak Category 1 storm Tuesday morning. The last thing the residents of Cuba or the Bahamas need is another storm moving over them, but they’re in the bulls-eye again with Ike.

After Ike moves back over water, he is expected to quickly reintensify from Tuesday through Thursday. His course takes him directly over the Gulf Loop Current, which has plenty of very warm water. It’s his course after Tuesday that has me really worried. Given the large-scale flow, Ike should continue curving toward the north. That should take him on another collision course with the northern Gulf coast. It’s way too early to talk about specific landfall sites, but I will venture a guess and say Louisiana, Mississippi and Alabama look like prime targets yet again.

Things are finally starting to quiet down just a bit in the Atlantic basin. Tropical Storm Hanna made landfall yesterday very close to where she was predicted to for a day or so prior to the event. All the models needed was for the upper-level disturbances to leave her alone and her track became pretty predictable. Here are her vitals of the update this morning:

Center located at 35.6N, 78.1W; maximum sustained winds of 50mph; moving NNE @ 21mph; minimum pressure of 985mb. T.S. Hanna is currently straddling the North Carolina/Virgina border. In the hours before landfall, she became much more tropical looking in her appearance. Her cloud shield extends quite a ways into the northeastern states. Rain from her bands is coming down at good rates throughout Virginia, Maryland and Pennsylvania.

T.S. Hanna is expected to weaken very slowly while moving around the Atlantic ridge. She will impact the northeastern U.S. for the next day or so before moving over southeastern Canada, then out over the open Atlantic. Her eventual path could take her to the north of Ireland and Scotland by Thurday. She will be a rainmaker with gusty winds the entire way.

Hurricane Ike’s future has been updated significantly since I last wrote yesterday afternoon. The strength and location of the Atlantic ridge is becoming better known. Where that ridge is and how strong it is will control Ike’s steering currents. Remember that Ike has a lot of mass, so any adjustments to his track requires overcoming a great deal of inertia. Here are Ike’s vitals this morning:

Center located at 22.0N, 67.9W; maximum sustained winds down a bit to 115mph; moving WSW @ 16mph; minimum pressure up significantly to 962mb. The 115mph winds still qualifies Ike to be a major, Category 3 hurricane. Right now, the official intensity forecast keeps him as a Category 3 storm over the next 24-36 hours. I’m still not convinced they’re picking up on the cooler waters that Hanna dredged to the surface in the region surrounding the Bahamas. The track forecast keeps Ike on his WSW path for the same time period, bottoming out in his curve Sunday into Monday.

The models have been fairly consistent in showing a pattern of curving Ike back toward the west, then northwest after that, but the location of that change has shifted forward in time with each model initiation. The latest initiations (early this morning) show Ike skirting Cuba’s north coast, maybe even coming ashore aways before moving back over the Atlantic, then passing through the Florida Strait on his way toward the Gulf of Mexico and an eventual U.S. landfall at an undetermined location. If Ike does interact with Cuba, I would expect him to weaken as we saw Hurricane Gustav do. The degree to which this occurs obviously depends on the specific amount of time Ike spends over land and the specific interactions of that land with his circulation.

An entry into the Gulf is no better than a strike over Florida or the east coast. In fact, due to the warm Gulf waters, it could potentially be worse for the eventual landfall. About the only thing working in the coast’s favor is the cooler waters located north of the Gulf Loop Current, which is what prevented Gustav from making landfall as a much stronger storm. Time will obviously tell.

Tropical Storm Josephine weakened to a Tropical Depression yesterday. This event was pretty well foretold yesterday as strong shear and dry air entrainment were identified all day. Her strength hasn’t changed today. Here are her vitals this morning: center located at 16.8N, 36.9W; maximum sustained winds of 30mph; moving WNW @ 9mph; minimum pressure of 1007mb. Josephine should continue along this trajectory the remainder of the forecast period. She isn’t expected to regain Tropical Storm status during that period at this time.

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One thought on “Atlantic Tropical Weather Update 9/6/08

  1. http://hummingbunny.wordpress.com/2008/09/01/tropical-storm-ike/

    I found out with Fay that you can copy and paste all the images on NOAA and they will update within a single post automatically. You can also copy and paste radar loops that run and update by themselves.

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