Isaac a Dangerous Storm for Hispaniola - U.S. to get Hit After

By: Levi32 , 3:56 PM GMT on August 22, 2012

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Tropical Depression #10 has formed well east of Isaac in the central Atlantic, and is forecasted to pass north of the Antilles islands. This storm can be safely ignored for now while we deal with Isaac hitting land.

Tropical Storm Isaac was named yesterday, and has shown a healthy increase in thunderstorm activity, though the center remains under the northern edge of the main convective mass, and the northeast quadrant remains void of thunderstorms due to light wind shear and a lack of low-level convergence in that part of the storm. Isaac has not deepened during the last 12 hours, and is only up to 45mph winds right now. Only gradual strengthening should occur as Isaac crosses into the eastern Caribbean near Guadeloupe today, and the intensity forecast continues to keep Isaac under hurricane strength on approach to Hispaniola due to the time it will take for the large circulation to tighten, and the fast trade winds in the eastern Caribbean. This is still a less aggressive short-term intensification scheme than the NHC, though their forecast has come down several notches over the last couple of days, and is closer to my forecast now. Isaac should weaken while interacting with the high mountains of the Greater Antilles, but once clear of them, should restrengthen faster than it did in the Caribbean, and could quickly become a hurricane in the vicinity of Florida if it gets at least a couple of days of water time.

The track forecast philosophy remains generally unchanged. The trough currently over the eastern U.S. is lifting out to the northeast, but the southern part of this trough is being left behind as a trough-split over the SE U.S. during the next few days. This will be helping to erode the western periphery of the Bermuda High as it retreats eastward over the Atlantic, and the models generally agree that this will create an open weakness north of the Bahamas in 48-72 hours. The models then diverge on whether Isaac will move right into this weakness. The CMC continues to be the easterly outlier, taking Isaac well east of Florida. The GFS has Isaac approach the weakness but get entangled with the greater Antilles and miss it, not recurving until it reaches southwest Florida. The ECMWF remains persistent that the weakness will close off and a rebuilt ridge will direct Isaac into the central Gulf of Mexico as a major hurricane. Thus, there is still a large amount of uncertainty beyond 72 hours. For now, the forecast track remains close to, but just east of the consensus of the non-ECMWF models, and takes Isaac into the Bahamas just east of Florida with the assumption that Isaac's large circulation will be able to feel the weakness in the ridge north of the Bahamas. However, there is considerable inherent uncertainty to the west and south of the forecast track due to Isaac's interaction with the greater Antilles. The high mountains there have a tendency to jerk storms around in an unpredictable fashion, and could throw the track off at any time. Additionally, any further entanglement with the islands could reduce Isaac's intensity and prolong his recurvature, putting Florida and the eastern gulf coast at greater risk. The forecast cone reflects this, and interests from the Carolinas to the central gulf coast should monitor Isaac's progress closely.

We shall see what happens!

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17. steelmagnolia44
12:27 PM GMT on August 23, 2012
Thank you, Levi. I'll be watching for your updates about Issac. Your analysis and explanations are always so clear and easy to understand. You definitely have a talent for this.

Member Since: August 24, 2005 Posts: 0 Comments: 45
16. LakeWorthFinn
2:27 AM GMT on August 23, 2012
Thanks Levi, I'm hooked to Tidbits :)
Member Since: October 6, 2005 Posts: 69 Comments: 7986
15. AllyBama
1:02 AM GMT on August 23, 2012
Good evening Levi...thanks for your thoughts on Isaac. I hate this watching and waiting period and am ready for Isaac to make a move now!
Member Since: August 3, 2006 Posts: 134 Comments: 20677
14. hurigo
12:11 AM GMT on August 23, 2012
Oh Levi, the presentation of your work is excellent, as though explaining complexities in easy to understand language is just... natural to you. I also very much enjoyed your explanation about your track cone and not using the NHC default, but rather showing/explaining that you had extended your cone to the west to allow for the (sorry can't think of the right word) but I expect you'll know what I am trying to say.

Good Job My Man!

Member Since: October 9, 2005 Posts: 100 Comments: 6819
13. AtHomeInTX
6:21 PM GMT on August 22, 2012
Thanks Levi. I can't imagine what Haiti will go through. And I don't want this in the gulf. Hopefully it will stay weak and east.
Member Since: August 24, 2010 Posts: 0 Comments: 591
12. seflagamma
5:41 PM GMT on August 22, 2012
Good job Levi,

There is a lot of area in that possible cone these days. Will just have to wait and see what the Islands to do Isaac.

Member Since: August 29, 2005 Posts: 315 Comments: 41228
11. waterskiman
5:34 PM GMT on August 22, 2012
Thanks Levi,

Yep I hope it shoots the gap (weakness) but wasn't to sure if that other low or spin coming down from above would keep it more southerly for longer.
Member Since: June 6, 2010 Posts: 0 Comments: 4654
10. acyddrop
5:27 PM GMT on August 22, 2012
Thanks for the update Levi
Member Since: October 12, 2010 Posts: 0 Comments: 48
9. Hoff511
5:17 PM GMT on August 22, 2012
Thanks Levi!
Member Since: September 2, 2009 Posts: 0 Comments: 274
8. kwgirl
5:09 PM GMT on August 22, 2012
Great Levi. I am hoping it follows the weakness up the East coast. Selfish of me I know:)
Member Since: March 28, 2008 Posts: 0 Comments: 1547
7. OGal
5:00 PM GMT on August 22, 2012

Great update Levi. You make so much more sense then any of our Orlando weather gurus. Keep up the awesome work and thank you.
Member Since: August 28, 2005 Posts: 72 Comments: 19224
6. rmbjoe1954
4:56 PM GMT on August 22, 2012

Thank you for your scientific analysis. I see you as a future NHC director- and good luck with your studies in Physics!
Member Since: June 16, 2005 Posts: 0 Comments: 2126
5. RobDaHood
4:34 PM GMT on August 22, 2012
Really great job explaining your thoughts. My uncertainty with this system is the "wild card" of the islands. You never know what you're going to end up with until it's back in the water.

Member Since: September 2, 2008 Posts: 121 Comments: 43080
3. johnbluedog69
4:29 PM GMT on August 22, 2012
Thank you levi,your forcasts are very well thought out.Your effort is very much apprieciated.
Member Since: October 26, 2009 Posts: 0 Comments: 438
2. catastropheadjuster
4:27 PM GMT on August 22, 2012
Levi~ Awsome Blog, you really explain it very well. At least to where I can understand it. Thank you for taking your time and doing this for us. We Appreciate it so very much. You have a great day.

Member Since: August 24, 2006 Posts: 21 Comments: 3689
1. moonlightcowboy
4:19 PM GMT on August 22, 2012
Excellent point on the larger degree of error on the south side of the cone. Good job, Levi.
Member Since: July 9, 2006 Posts: 184 Comments: 29682

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Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.

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