Clark
(Meteorologist)
Wed Aug 10 2005 06:18 PM
Re: Irene's unpredictability

emackl -- please, by all means, feel free to ask if there's something you don't understand. We'll be more than happy to help you out.

As for Irene...nice little transformation today. The older bits of Irene appear to be the sharp trough with weak rotation along 22-28N/62W, while the center has reformed with the mid-level organization early on today. The QuikSCAT passes last night gave some idea that some reorganization was occuring, while the visible satellite imagery today gives us a better idea of what has occurred. It's similar, it seems, to what it did several days ago with new LLCs forming...except this time, it wasn't the northern & western one that won out.

The storm is still a bit disorganized -- as of this time, my best guess on the center's location is 23N/58W, placing it a bit on the NW side of the convection -- but getting better organized with time. If current trend continue, the system should be a tropical storm later tonight. It's pretty much where we thought it'd be once it initially formed, but it's gotten there for all of the wrong reasons (compared to predictions) and is nowhere near the caliber of storm that was predicted.

That said, the threat to somewhere along the SE/Mid-Atlantic coast is rising...the strength of the storm and the strength/extent of the ridge will give the keys as to where. I don't feel safe excluding anyone along the US coastline at this point, including South Florida. There will be a chance for Irene to turn more towards the north at days 4 and 5; how much of a turn, as noted, depends upon how strong it is and what the upper-level pattern looks like at that point. For now though, everyone needs to be watching this one for a potential US impact in 5-6 days. Intensity...NHC intensity looks good initially, maybe a little stronger in the long run assuming the favorable upper-level winds come into play and as the storm hits the Gulf Stream. The absolute high end of intensity is cat 2/3 status, I feel -- conditions are ripe, but not all that ripe -- with weak hurricane status (cat 1, 75-85mph) more likely at landfall. We'll be watching this for any changes, however.

Elsewhere...potential is there for another central Atlantic development in about 3 days, but it's likely to start out weak. Colorado State's Experimental TC Genesis product (http://www.cira.colostate.edu/ramm/gparm/genesis.asp) has spiked upward lately, with conditions becoming increasingly favorable, so it's only a matter of time. One to watch for the longer-term...give it, say, a 30% shot at development right now. We've changed around our MM5 (http://moe.met.fsu.edu/mm5/) a bit in an attempt to reduce the number of terrain-induced vortices; we'll have to see how it impacts the overall forecasts, but results are promising so far.

More tomorrow...



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