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Since I got a few emails about this this morning.... Things may change pretty quickly with Dolly, so just wanted to put up a reminder to keep watch, especially through the afternoon. Although the westerly track is more likely, if Dolly does get organized and gains strength then northerly is definitely possible as well.

Dvorak T Numbers are around 3.0, so it is doing pretty well convection wise right now. If recon finds evidence of a Low Level Circulation then those numbers will be important.

Everyone in that forecast cone needs to be watching this system.

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Right now Dolly is being guided swiftly along by a ridge axis over the SE U.S. However, most global numerical models predict the influence of this large scale synoptic feature to wane enough to weaken the steering field substantially. This should induce a slowing of the forward speed beginning at ~ 60 hours.

It should be noted that in addition to slowing...a few of the overnight track guidance have shifted substantially north of the previous runs. The 06z GFDL and HWRF, for example, take Dolly to over 90kts and bring her ashore in the TX Bend area...perhaps missing Mexico altogether in these solutions. While such details are far from certain, you do bring up a good point that might be a harbinger, relating to a stronger system having more polar-ward ascent. Overnight...as we noted by a number of posters and apparently confirmed, Dolly did a center jump, such that much of her circulation managed to stay over water...not encountering the deleterious effects of land. This asserts a stronger ramp up curve (potentially), but more importantly, most of the past guidance was based on a weaker system that passed more bodily over the Peninsula. Since that did not take place, the 12z runs will be more telling.

There is a con and a pro at the moment, to faster intensification:
A broad circumavallate requires a longer duration to concentrate a core;
In about 1 day, Dolly will be moving headlong across a very rich oceanic heat content, where the thermocline extends quite deep...indicating more than the usual heat content (we saw what Katrina did when she passed over such feature in the eastern Gulf).

..Because the overall environment has recently gone from marginal/shear, to very little shear with an upper level anticyclone sprawling all the western Gulf, I'm going to go ahead assume the upper ends of the intensity spectrum will be achieved. Part of this decision is also based on tropical cyclones, once garnered enough momentum, tend to exceed guidance better than 50% of the time. Since (finally) a real central axis to the circulation is definable (hi res visible imagery), she's developing an inner core and it appear that threshold is nearing. I like the NHC's idea to go a bit aggressive, while perhaps conserving a little do to Dolly's large size.

Edited by typhoon_tip (Mon Jul 21 2008 05:03 PM)

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