Eric Berger

2pm CT Saturday: Tropical Storm Beta made its expected turn west earlier today and is now crawling toward the Texas coast at 2 mph, according to the National Hurricane Center. Its maximum sustained winds are 60 mph. Our overall forecast for the Houston metro area has not changed at this time: We still anticipate Stage 2 flood conditions south of Interstate 10, and Stage 1 for areas north of Interstate 10. Bottom line: We have not seen anything today that makes us any more concerned.

I want to start with a satellite image of the Gulf of Mexico this afternoon that illustrates water vapor—a good proxy for convection. When you look at this image there are a couple of important things to notice. One, the precipitation associated with Beta is strongest near its core and well to its east. Second, the reddish hues across Texas indicate dry air. Some of this dry air is wrapping into the circulation of Beta, which is helping to hamper its intensification. Finally, it’s clear that until Beta moves further west the bulk of its precipitation is going to fall over the Gulf, or southern Louisiana.

In this afternoon post I want to discuss the timing of what to expect after today, and when. The usual caveats apply, this is a dynamic weather system, so forecasts will change. But this is our best guess as of 1:30pm Saturday afternoon.

Sunday

Beginning fairly early on Sunday we could see some outer rain bands from Beta moving into the Texas coast. Most likely these will be light to moderate, at least during the daytime hours. Coastal areas may see upwards of 1 to 2 inches of rain, but inland areas will likely see less. All in all, this should not be too disruptive. Coastal areas may see tides 3 to 4 feet above high tide levels, particularly on Sunday evening, and Monday morning. Tropical Storm force winds may arrive along the coast, from Matagorda Bay to Galveston by Sunday evening or during the overnight hours.

Monday

Most of the best available model guidance suggests we will see similar conditions on Monday as the storm’s center nears the Texas coastline, probably near Matagorda Bay. I should note that overall confidence in this track remains somewhat low, and that a northward jog in the track would bring more serious winds and surge into Galveston Bay. However, we don’t expect that right now. Beta will likely will be a high-end tropical storm or a low-end Category 1 hurricane at this time. Winds will probably increase across the Houston area, although I’m not sure they will reach Tropical Storm-force.

Tuesday and Wednesday

These are the days when we can probably expect the heaviest rainfall, although amounts are still to be determined. This is the period when we expect Beta (or the remains of Beta) to begin lifting to the north and then northeast, perhaps bringing its circulation near the Houston metro area. By Thursday we should see improving conditions across Texas.

So really, how much rain?

If you remember the satellite image at the top of this post, almost all of the convection and strong storms lay to the east of the storm’s center. We think that the most likely scenario is that this pattern continues during the coming week, and we end up with a situation where most of the Texas coast north of Corpus Christi sees 4 to 12 inches of rain over the next week, with lesser amounts inland. This is very general, ballpark value. The key thing to remember is that this scenario would not lead to widespread, catastrophic flooding.

However, we cannot discount the possibility of Beta really getting its act together over the next day or two, and becoming a prodigious rainmaker over Texas. In this reasonable worst-case scenario, areas from Matagorda Bay to Galveston to Beaumont are at risk for 20 inches or more of rain, with 10-plus inches for parts of Houston. That is the high-end risk. But again we do not favor that scenario right now; and if our view changes we will let you know post-haste with a hasty post.

Our next update will come no later than 8pm CT this evening.

Good Saturday morning! We’ll be with you here all weekend on Space City Weather to track the progress of Tropical Storm Beta, and its effects on Houston, Texas, and Louisiana. Broadly speaking our forecast has not changed a whole lot. For now, on our Flood Scale, we are still calling for a Stage 2 flood for areas south of Interstate 10, and a Stage 1 flood for areas north of Interstate 10.

With this system we are most concerned about the potential for heavy rainfall next week, and then rising seas along the coast due to a prolonged period of winds from the east-northeast. Probably the most important thing we can tell you this morning is that there is still a lot of uncertainty in the track forecast for Beta, and where the storm’s heaviest rains will fall. We suspect this storm will have some surprises in store.

Track

As anticipated, Tropical Storm Beta has moved north overnight, and now lies nearly 300 miles due east of the mouth of the Rio Grande River. Pretty soon we expect the storm will run into a ridge of high pressure and take a westward turn, gradually moving toward Texas. We are reasonably confident that the storm will then approach the Texas coast somewhere between Corpus Christi and Matagorda Bay on Monday, potentially as a strong tropical storm or a Category 1 hurricane. Through Monday this track should keep most of the heaviest rainfall just along, or off the coast. So far, so good.

The problem is that, after this point, we’re not really sure what will happen. The National Hurricane Center’s official track brings the storm to the northeast on Tuesday, along the Texas coast, as weakening high pressure allows for an exit. However, it also seems possible the storm could move 50, or even 100 miles inland before making this turn, or remain 100 miles offshore. I know what you’re thinking, slow-moving storm, landfall near Corpus, moving inland—Eric, that sure sounds a lot like Hurricane Harvey. Well, I’ll agree, but there are some key differences here. Most significantly, Beta lacks Harvey’s organization, and will be fighting dry air as it moves toward Texas. This may help to limit inland rainfall. Moreover, the storm really should move away by Tuesday or Wednesday, so we are probably not looking at a four- or five-day heavy rainfall event.

Rainfall

So how much is it going to rain next week? The global models have trended slightly downward in terms of rainfall accumulation during recent runs, and I think a good general expectation is 2 to 8 inches across much of the Houston metro area, with coastal areas potentially seeing 6 to 12 inches between later Sunday and Thursday. That much rain over four days is manageable, so our concerns are very high rainfall rates—which tropical storms produce—and higher than anticipated totals. We can’t rule out some 20-inch bullseyes, but so far there’s not much support for this in our best models. I think the bottom line is that we need to prepare for heavy rainfall through Wednesday or so of next week, and the possibility of flash flooding. But it may not come to that.

Storm surge

The other issue we’re going to face is storm surge as Beta produces strong easterly winds over the area. For now, Hurricane Laura’s water levels, plus one or two feet, is probably a good guide for what to expect from Beta along Galveston Island, Bolivar Peninsula, and Galveston Bay. However, this part of the forecast remains very much subject to change, given Beta’s track and intensity.

Winds

Winds will begin to increase across the area on Sunday and Monday, and there is a 30 to 40 percent chance that the Houston metro area will see tropical-storm force winds next week, with higher chances along the coast. This forecast, too, is very dependent on track and intensity so winds are a work in progress. But right now the expectation is that wind should not be too disruptive in terms of power outages across Houston.

Our next update will be posted no later than 2pm CT today.

Welcome to another crazy day in the tropics. While we we’ve been waiting for Tropical Depression 22 to strengthen into a tropical storm, a system in the deep tropics became Wilfred this morning. And then, at noon, Subtropical Storm Alpha improbably formed off the coast of Portugal. Neither of these storms remotely concern the Gulf of Mexico, so our focus will remain on the depression that will become—checks notes—Tropical Storm Beta later today.

We are issuing our first Flood Scale forecast for this depression, with the caveat that this is subject to change. Simply put, there remains a healthy amount of uncertainty about where the heaviest rains will come over the next five or six days. However, for now, we are calling for a Stage 2 flood for areas south of Interstate 10, and a Stage 1 flood for areas north of Interstate 10. The biggest rainfall risks for Texas are right along the coast, from Brownsville to Galveston.

Now let’s talk track, because that ultimately will determine what happens with the depression’s rainfall.

Where will Beta bend?

This will be the story of two turns. The following graphic shows the National Hurricane Center’s official forecast track (as of 10am CT Friday) in black. I’ve made several annotations that I want to talk through to help you understand the track forecast and the uncertainties that we’re dealing with.

Alright, so we’re fairly confident in the storm’s track today and tomorrow, when it should run into high pressure associated with the front that has moved through Houston already. This should push the system westward, toward Texas. The big question after this is how far west the storm will get—probably very close to the coast, and perhaps even a little bit inland (I’ve tried to highlight this area with the white rectangle). The storm does its coast-hugging, slow moving routine on Monday. At this time it will produce a lot of rain, but hopefully most of this will fall east of the center, offshore.

The second turn

By around Tuesday, the storm should begin to lift to the north and then northeast, perhaps moving close to the coast (as indicated by the official forecast), or further inland (wetter for Texas) or further offshore (drier). Because we have so little confidence in the track for Tuesday and beyond it’s hard to say how much rainfall we will see in the Houston region. For example, I could envision 5 inches of rain in Galveston, or 20 inches. I could envision 2 inches of rain in Houston, or 8 inches. We’re pretty confident that rain chances will perk up on Sunday, with the really heavy stuff possible from Monday through perhaps Thursday morning. For more precise totals you’re going to have to hang in there with us until we get a better handle on the storm’s track.

Coastal flooding

The other issue is coastal flooding. Generally, we anticipate the potential for water levels to rise 1 to 2 feet higher than the region experienced with Hurricane Laura three weeks ago. Waters will start to rise on Saturday, and increase on Sunday. After that any additional rises will depend upon the intensity of the depression—we still think it’s going to become a tropical storm or a Category 1 hurricane at most—and its track. So these hazards are to be determined as well.

That’s all we have for now. Matt will have our next update at 8:30pm CT this evening. By that time Beta probably will have formed. Alas, Beta won’t be a fish storm.