Weather Nerd

T.S. Dolly nears hurricane strength

Tropical Storm Dolly’s intensification has finally begun in earnest, with the minimum central pressure dropping to 993 millibars and winds increasing to 65 mph overnight. Hurricane strength begins at 74 mph, and Dolly will likely reach that threshold soon. As Michael Cornelius at FLhurricane.com puts it, “Dolly should become a hurricane later this morning and likely gain strength throughout the day.”

The Houston Chronicle‘s Eric Berger writes: “Tropical Storm Dolly finally appears to be developing an inner core . . . [so] the storm could intensify more rapidly now.” The main reason for this new development is that a cut-off upper-level low pressure system, or “TUTT,” that had been interfering with Dolly’s development all day yesterday — much moreso than forecasters expected — has finally moved off. As a result, Dolly now finally has free reign to intensify. Alan Sullivan writes that Texans should be grateful for the TUTT’s influence:

If that feature had not lingered, Dolly could have intensified explosively. However the adverse influence will fade as Dolly approaches the coast, and the storm will be strengthening rapidly as it makes landfall. Such systems are often more destructive than fading hurricanes. That said, however, it is unlikely that Dolly will get strong enough to be really dangerous.

The official forecast has Dolly reaching 85 mph at landfall. “Given the potential for rapid intensification, however, a stronger storm cannot be ruled out,” Berger writes.

In any case, in Cornelius’s words, folks in the Hurricane Warning areas “should rush any more preparations today as conditions will start to deteriorate this evening.”

Dolly has slowed down, as expected, to a forward speed of 13 mph. Landfall is projected for around midday tomorrow, near the Texas-Mexico border. The official forecast track has shifted ever-so-slightly to the left, and the NHC is now forecasting the storm’s center to come ashore in Mexico rather than Texas. However, the 5:00 AM EDT discussion emphasizes that “DUE TO THE INHERENT UNCERTAINTIES…ONE MUST NOT FOCUS ON THE EXACT LANDFALL POINT IN THIS FORECAST.” Moreover, the strongest winds and storm surge will be in the storm’s right-front quadrant, which, on the current track, would include the southernmost coast of Texas. Brownsville may be in for a rough Wednesday.

Barring unexpectedly rapid intensification, Dolly’s biggest impact will probably be very heavy rainfall. Berger writes:

The latest rainfall estimates from the National Weather Service … suggest[] that a large chunk of the southern Texas Valley could get as much as 11 inches of rainfall from Dolly, with even more in some areas. The storm’s rainfall potential is enhanced because Dolly’s forward motion is expected to decelerate before landfall.

The Colonias, largely clustered just inland from the Gulf and in the storm’s path, could be especially hard hit by Dolly.

Unfortunately, it appears that the most drought-stricken areas of Texas won’t get much relief from Dolly’s rains.

I’m going to be incommunicado again until around 2:00 PM Eastern today. I’ll try to post a brief update shortly after 2:00, before I have to head to the airport. After that I will, unfortunately, be unable to blog for most of the late afternoon and evening, though I may be able to sneak a quick update from an airport here or there. Regardless, you can keep abreast of the latest developments by checking the National Hurricane Center website and the various sites linked in my blogroll at right. Also, here are some other links to visit:

P.S. The Houston Chronicle reports that “Texas officials said they wouldn’t order evacuations along the coast unless Dolly strengthens to a Category 3, with sustained winds of at least 111 mph.” Of course, at this point, if Dolly does unexpectedly strengthen to Cat. 3 status, it’ll be too late to order evacuations! But that’s unlikely to occur.

The Brownsville Herald reports that “no regional evacuations are expected, [but] county judges – who are in charge of emergency management in their jurisdictions – retain authority to call for a mandatory evacuation in their areas.” If they’re going to do that, they need to do it now, because conditions will begin to deteriorate later tonight.