Eric Berger

Harvey redevelops in southern Gulf, will bring major rains to Texas

Just a quick post to note the official redevelopment of Harvey as a tropical depression in the southern Gulf of Mexico. The forecast track mirrors what we’ve been discussing for a couple of days now—the movement of a tropical storm into the Texas coast, after which its slows down, and drenches the eastern part of the state.

Official forecast track for Tropical Depression Harvey. (National Hurricane Center)

The official forecast predicts Harvey will reach hurricane strength—barely a Category 1 storm with 75mph—before it reaches the Texas coast. Tropical Storm watches are in effect for Galveston and the Galveston Bay area. Hurricane watches are in effect for Brazoria County, and areas southwest of Houston. But the primary concern with this system remains widespread rainfall and inland flooding. The hurricane center’s rain forecast for Harvey reflects this:

(National Hurricane Center)

Our forecast from this morning largely holds up, as it is based on similar model data that made up the National Hurricane Center’s outlook. We will post a more comprehensive update this afternoon, around 2:30pm. In the meantime, here is what Matt and I feel you should bear in mind about the next several days.

  • The rainfall hype is real and serious, and although it’s impossible to specifically forecast it at this time, you need to be aware of the threat.
  • The forecast is going change, and in systems like this trying to pin down who gets maximum rainfall is extraordinarily difficult. Patience required.
  • The rains will be spread out from Friday through Tuesday, but for Houston we continue to expect the heavier rain during the latter half of that period.

 

Harvey to re-form soon, bring flooding to the Texas coast

Houston will see continued warm weather—with highs in the low- to mid-90s—and scattered showers during the next couple of days, but our principal focus remains on the likely redevelopment of Tropical Storm Harvey, and its eventual movement toward Texas. Parts of the state will be be utterly soaked by the end of this weekend, and some flooding seems inevitable.

Tropical Storm Harvey at 6am CT on Wednesday. (Space City Weather/NOAA)

As of 6:30am Wednesday, a reconnaissance aircraft is flying around the large area of disturbed weather in the southern Gulf of Mexico, and may find a tropical depression. Some dry air appears to be slowing development right now, but the Gulf is warm and wind shear manageable, so some intensification is likely as the system moves northwest toward Texas during the next couple of days. While we cannot rule out rapid intensification, a phenomenon which is still relatively poorly understood, it is probable that Harvey will come ashore as a tropical storm or Category 1 hurricane. A landfall between Corpus Christi and Matagorda seems most likely at this time. While we may see some storm surges of 3 to 5 feet with such a storm, and tropical storm-force winds, rainfall is by far the biggest concern.

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Yeah, this weekend is looking wet for Texas

Until the remnants of Tropical Storm Harvey are no longer a threat to Texas, we’ll be posting multiple times a day on this site to provide the best available information. Unfortunately, after looking at the latest model data we continue to be concerned about the potential for this tropical system to bring heavy rains to the Texas coast and some inland areas this weekend, and early next week.

As of Tuesday afternoon, the remnants of Harvey are crossing the Yucatan Peninsula, and it appears almost certain that the storm will re-form over the southern Gulf of Mexico during the next 24 to 48 hours.

As of Tuesday afternoon Harvey had not re-formed. Yet. (NOAA)

The forecast models suggest the storm will then move toward the northwest, and come ashore somewhere on Friday(ish) between Brownsville, at the southern end of Texas, and Freeport, which is just down the coast from Galveston. This afternoon, NOAA’s G-IV Hurricane Hunter Jet will fly around the remnants of Harvey, and this should provide useful information that will improve forecast model output tonight, and especially on Wednesday. But frankly, our biggest concern is not where undead Harvey makes landfall (rain, not winds, are most likely the primary threat here), but rather what happens after the storm moves inland. This is because the upper-air pattern later this week and weekend is such that there will be little to steer the movement of the system, and therefore it may wobble around. When you have a tropical system near the warm, moist Gulf of Mexico, this is a bad thing because it means rainfall. Potentially a lot of rainfall.

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Texas faces a tropical threat later this week, heavy rains possible

Houston enjoyed reasonably good weather for the partial eclipse on Monday, and perhaps what was most striking to me is how pleasant it felt outside shortly after 1pm, when about two-thirds of the Sun was obscured by the Moon. If only every August afternoon felt like that. In any case, it is now time for us to focus on the weather, with the potential for a very wet weekend due to tropical moisture.

Photo taken of the eclipse maximum, from Friendswood, with Celestron 8″ telescope. (Darrell Lee)

Tuesday through Thursday

Houston will remain in a summer-like pattern for most of the rest of the work week—with highs in the low- to mid-90s and scattered afternoon showers—with a few twists. Most notably, a cool front will sag into the northern parts of the Houston region by late Wednesday or so, and while this won’t provide much relief from the heat it could raise rain chances a little bit.

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