Tuesday, July 22, 2008

Dolly Update: Dolly Still Threat to Western Gulf


Note: 12z=8AM EDT...0z=8PM EDT
Discussion:
Dolly's interaction with the Yucatan, although brief really disrupted the circulation last night, so Dolly has spent all of today trying to develop an inner core, so it really hasn't strengthened yet. However, it looks like a small inner core has formed, and now an "eyewall" is trying to form, although up to this point it isn't very pretty yet. The reason the system is having a tough time wrapping deep convection all the way around the center is because of dry air off to the SE of the COC. However, it appears that Dolly will be moving away from the dry air, which should help convection wrap all the way around the center. Right now, outflow is good in all quadrants except the S/SE quadrant, where some dry air is getting pulled into the system. Also, wind shear is very low and is expected to remain that way. Also, oceanic heat content is moderately favorable for intensification in Dolly's path over the next day. So, over the next day, once Dolly can wrap that "eyewall" all the way around the center, I see no reason while a modest to fairly quick strengthening won't occur. After that, all factors will remain favorable for intensification, except for oceanic heat content which will become a little less favorable for intensification. It will not cause a weakening in Dolly, but will slow strengthening. This little "cooler eddy" of water as described by the NHC may save the western Gulf coast from a major hurricane, but again with modest to good conditions for strengthening over the next 36 hours while it is over water, I believe a CAT 1 hurricane will easily be reached, if not a CAT 2. (less bullish than yesterday, due to inner core taking longer to get organized) Now that you know the reasoning for the intensity forecast, here is the reasoning for the track:
The reasoning for track is similar to yesterday, but with a more westerly movement than expected today, the track has been shifted slightly to the left. Currently, a ridge is keeping Dolly on more of a westerly track rather than a NWerly track. However, this ridge is expected to break down over the next day and allow Dolly to move more WNW. The ridge breaking down will also cause Dolly to slow down some over the next day. However on Wednesday as Dolly approaches landfall, a ridge will start building to the north of Dolly. This will nudge Dolly more to the west again just before landfall. Right now, this solution is supported greatly by all models, as there is a very tight model consensus for both track and speed. Landfall looks to be very near the TX/MX border. This could pose a threat to the Brownsville area which is fairly heavily populated.
Forecast intensities:
12z Tue: 55 knots
0z Wed: 65 knots
12z Wed: 80 knots
0z Thu: 50 knots
Landfall intensity: 85 knots (~97MPH)
Not as bullish as yesterday, due to the Yucatan disrupting the circulation more than expected (not surprising, given that it was a developing cyclone), but you can't blame me for being a little bullish at first, because all the factors were/are there for intensification, but the center took a while after getting back out over water to organize. Still, far southern TX/northern MX need to prepare for a storm surge of 4-7', power outages, and perhaps some structural damage, especially to mobile homes.
NOTE: Some of the links are time sensitive, and I wrote this around midnight. I believe the NHC link, dry air link, shear link, and model link are all time sensitive, so they may not look exactly the way they did when I wrote this discussion.

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