Eric Berger

In brief: On Friday afternoon the National Hurricane Center began tracking an area of low pressure over the northwestern Gulf of Mexico. To put this threat into perspective, we’re going to share content published earlier today on The Eyewall. Though a serious system is not likely to develop, locally heavy rain and flash flooding are a good bet along the coasts of Texas and Louisiana into next week

We’ve been discussing it all week on The Eyewall, but low pressure has now officially formed in the Gulf, with a surface low analyzed offshore of Galveston and Sabine Pass. The National Hurricane Center now highlights this area with a 20 percent chance of development.

The surface low is rather broad, so it’s not as if we have a rapidly intensifying tropical system off the coast. But we have low pressure in the Gulf, which is always something of note. Any development risk from this is very low-end in terms of winds and waves. But in terms of rain, this will be a source for some serious coastal rainfall in the coming days, development or no development. Rain totals through next week may tally up an additional 5 to 10 inches between Galveston and Vermilion Bay in Louisiana.

While there are no flood watches posted currently (except in the New Orleans and Baton Rouge areas), there is some potential for flooding to occur in coastal counties and parishes. Places like Galveston, Port Arthur, and Cameron through Morgan City and New Orleans could definitely see at least localized street flooding crop up. With a surface low now offshore, most of the rain will likely consolidate around that feature, meaning that inland places like Houston and perhaps Lake Charles see less rain, less often.

This will be a very coastal-focused feature. The low should meander in the days ahead offshore. Thankfully, upper level conditions aren’t super conducive for development, so again any organization or strengthening would probably be very sluggish and the ceiling from this is rather low it seems. As the system meanders, it could end up onshore in Louisiana or back toward the middle Texas coast, so proximity to land will also act against its development.

Bottom line: This is not a major concern, but it bears some watching and it will, at the least, deliver locally heavy rain and flash flooding potential on the Texas and Louisiana coasts.

In brief: Today is the first of several days, likely lasting through the Labor Day weekend, that the Houston area will be subject to the potential for widespread showers and thunderstorms. For most of our region these will be a nuisance, but for the immediate coast there is the potential for street flooding, which is why we’re initiating a Stage 1 flood alert for coastal counties.

Stage 1 flood alert

We are putting this flood alert, based upon our flood scale, in place due to the potential for heavy rains near the coast during the next several days. A Stage 1 alert simply highlights the potential for intermittent street flooding, particularly in low-lying areas, and possibly along some feeder roads. I anticipate keeping this alert active through Labor Day Weekend.

It applies to coastal counties across our region: Matagorda, Brazoria, Galveston, Chambers, Jefferson, and Orange. Essentially, that’s the entire upper Texas coast. The reason is that these areas will be closest to the source of moisture, and susceptible to the most frequent rainfall. Some of our latest modeling indicates the heaviest rains will be further east, in the Beaumont-Port Arthur area, but I feel the entire upper Texas coast is at risk. These coastal areas could see 5 to 10 inches of rain over the next week, with higher isolated totals.

Thursday and Friday

After rainfall of a more scattered nature for the last couple of days, showers and thunderstorms should become more widespread beginning today. As noted above, rain chances will greatest right along the coast, but all locations along and south of Interstate 10 will be prone to periods of medium- to heavy rainfall, with lesser chances further inland. Rains today and Friday will be driven by a combination of lots of moisture in the atmosphere along with an upper-level low pressure system that will help drive the formation of storms.

Based upon high-resolution modeling, which is not great but the best we have, I anticipate showers and thunderstorms to start developing over coastal areas around 8 to 10 am this morning and then persist, on and off, for much of the daytime. Activity may diminish somewhat this evening before redeveloping on Friday. With plenty of cloud cover, high temperatures today should remain in the upper 80s for most locations, although some inland areas with scattered sunshine may reach the lower 90s.

Labor Day Weekend

Widespread showers and thunderstorms, particularly for coastal areas, will likely persist from Saturday through Monday as the atmosphere remains ripe for showers. Houston, particularly inland areas, will not see wall-to-wall rain this weekend, but there definitely will be the potential for storms to pop up and mar outdoor activities. Intermittent showers and clouds should help keep highs to the upper 80s to about 90 degrees for most locations this weekend, so this will definitely be one of the cooler Labor Day Weekends we have had of late.

Next week

Rain chances will persist on Tuesday and Wednesday before slackening some toward the second half of next week. This probably will allow high temperatures to claw their way back into the lower 90s. I don’t want to jinx anything, but there is a non-zero chance of a weak cool front pushing through in the September 8 to 10 period. Right now I would give it about a 25 percent chance, based on the medium-range modeling. Even if it doesn’t happen, the mere fact that we’re looking at the possibility of fronts suggests that fall may not be all that far off.

Tropics

As August comes to an end, the lull we’ve been enjoying for awhile now is likely to come to an end as well. There is increasing model support for the development of a tropical system in the Central Atlantic which will then move toward the Caribbean Sea. After that? There’s not agreement in the models, so pretty much anything could happen. But given that we’ll be in early September at that point, it’s definitely worth keeping an eye on the tropics.

In brief: Today will again see scattered rainfall across the metro area before more widespread showers and storms push into our region beginning tomorrow. The period of Thursday through next Tuesday should see daily rain chances above 50 percent, so make any Labor Day plans in Houston and Galveston with a backup indoor option.

Wednesday

Today is probably the final day with only “scattered” showers and thunderstorms rather than more widespread storms. Locations south of Interstate 10 probably have about a 50 percent chance of rain today, with lesser chances inland. Skies will, accordingly, be partly sunny and high temperatures for most regions are likely to reach the lower 90s. This probably will be our hottest day for the next week. Low temperatures will drop into the upper 70s on Wednesday night.

Thursday and Friday

Rain chances will be higher to end the work week, likely in the vicinity of 70 or 80 percent for most locations. I expect these to be mostly passing showers, so accumulations during each storm will likely be one-half inch of rain, or less. With partly to mostly cloudy skies, most locations should see high temperatures in the upper 80s to around 90 degrees.

Labor Day weekend

Unfortunately, if you were hoping to end summer with a beach bash over Labor Day weekend, you’re likely to be disappointed. The combination of plenty of moisture from the Gulf of Mexico and a couple of upper-level low pressure systems will keep the threat of daily rainfall high, especially for locations closer to the coast. Daily rain chances over the holiday weekend will be in the 60 to 80 percent range. These showers won’t last all day, to be sure, but they’re likely to put a damper on outdoor activities. Highs will range from the upper 80s to about 90 degrees for most locations.

Next week

Conditions on Monday and Tuesday of next week may become even more favorable for showers, and the potential for heavy rainfall. We’re not ready to call for a Stage 1 flood alert for coastal areas, as I want to see more data. But the potential is there. Regardless, the threat of moderate to heavy rainfall will persist for the entire region, along with highs in the upper 80s to 90 degrees.

By Wednesday or so, the potential for widespread showers starts to diminish, and the latter half of next weekend probably will start to see more sunshine and less rainfall. Highs probably will get back into the low-90s.

Tropics

The National Hurricane Center is continuing to track a couple of areas that have a low-end chance of developing, but in terms of the Gulf of Mexico there is not a whole lot that gives me pause about the next week or so.

In brief: Houston will continue to see scattered showers and cooler temperatures for a couple of days. Then, rain showers should become more widespread during the second half of the week, and we are starting to see the possibility of heavy rainfall by next Monday or so.

Potential flooding

Over the last day or so, the model trends have been pushing toward a wetter pattern than expected for the next week to 10 days. Since the region has been so dry, and rain chances will be hit or miss over the next several days, I’m not anticipating any serious flooding during this week. However, in part due to a front stalling north of the region early next week, we could see the potential for more widespread and sustained showers.

The bottom line is that we’re watching things, and something like a Stage 1 flood alert may be necessary for early next week, potentially the Monday and Tuesday time frame, for coastal areas. Again, even in a worst case scenario, we’re probably talking about something that floods lower-lying streets. I just wanted you to be aware of our thinking.

Tuesday

Today will be something of a repeat of Monday, with showers developing offshore and moving inland during the morning and early afternoon hours. However, coverage does look likely to be slightly less than on Monday. Skies, otherwise, will be partly sunny, with highs in the low 90s. Rain chances will slacken during the evening hours. Lows on Tuesday night will drop into the upper 70s.

Wednesday

Like on Tuesday, rain Wednesday will be of a fairly scattered nature, with perhaps only about half of the area seeing a passing shower. Accumulations should not be too significant, with the hardest hit areas perhaps picking up a half inch or so, and most of the region less. Highs, again, should be in the vicinity of the low 90s with partly sunny skies.

Thursday, Friday, Saturday, and Sunday

Rain chances will increase as we get into the second half of the week, and weekend. I can’t find much to differentiate the weather on any of these four days, which is why I’ve lumped them together. Each day is more likely than not to see rainfall, and there will be chances for showers overnight as well. High temperatures each day will range from the upper 80s to lower 90s, so quite a bit cooler than is typical for late August. I don’t really have any flooding concerns for this period, but showers could definitely put a damper on outdoor activities. It certainly won’t be raining all the time, but showers may pop up any time.

Early next week

As a front stalls north of the area, this should provide some additional lift and juice our rain chances. Since we’re talking about a period a week from now, the details are going to be hazy. But with the potential for widespread showers, and some heavy rainfall, we necessarily cannot rule out the possibility of some flooding. We’ll see. Daily highs will remain in the vicinity of 90 degrees. Most of our modeling shows rain chances slackening as we get toward the second half of next week, for what it’s worth. Which probably is not a whole lot.

Atlantic tropics

After a quiescent period, there is a new system to watch. There is a chance that an area of low pressure in the Atlantic could develop over the next week or so, as it moves toward the Caribbean Sea. Yesterday afternoon some of our best global models were hot to trot, and ready to develop this system into a tropical storm, but this morning they’ve backed off some. There’s not much else we can do but watch at this point—the next month is the period during which we should be most concerned about the potential for powerful hurricanes to strike Texas. For more detailed coverage, be sure to check out The Eyewall.