Year: 2020

A tropical depression has formed in the Gulf, and Texas needs to pay attention

Good evening. The National Hurricane Center says a tropical depression has formed in the Gulf of Mexico, and this system may become Tropical Storm Wilfred in the next day or so. Before we get too deep into the forecast I just wanted to highlight a couple of changes from this morning’s post:

  • The depression is expected to begin moving northward a little sooner than expected, so impacts for Texas could occur sooner
  • The forecast models are now in a little better agreement that the tropical system will come near, or possibly even ashore the Texas coast, increasing the rainfall threat

Alright, now let’s jump into the forecast. The 6pm CT “track” prediction from the hurricane center highlights some of our uncertainty when it comes to the depression. After the storm moves slowly north on Friday and Saturday it should run into high pressure building over Texas after the passage of a front. This is what will likely push the system westward, toward Texas.

6pm CT Thursday track forecast for TD 22. (National Hurricane Center)

After Sunday we’re deep into the realm of speculation, as we’re not sure what will happen by Monday or so. The system could plow west or southwest into Southern Texas or Mexico (track “A”) in the map below. It could follow a track up the Texas coast (“B”). It may also essentially stop, and get pulled to the northeast, toward Louisiana, as the high retreats (“C”). We really do not know and anyone who says they do know right now is not being honest with you. Each of these tracks would have drastically different outcomes for Houston, which is why our overall confidence in next week’s weather is very low.

The National Hurricane Center anticipates the storm will gradually strengthen and come near hurricane strength by Sunday. While the Southern Gulf of Mexico is fairly warm—plenty so for strengthening—the storm will likely take on dry air from the north which will not help its organization. Moreover, a slow-moving system will churn up cooler water from deeper in the Gulf. Bottom line: While we’re always concerned about September storms intensifying in the Gulf, in this case we’re more concerned about the moisture from this system than winds.

Any number of possibilities are open with the depression’s track next week. (National Hurricane Center)

As we’ve been saying, the depression has the potential to become a prodigious rainmaker over the next week for Texas and northern Mexico. We think the cold front and storm’s position will probably keep its heavy rainfall offshore through this weekend, but by Monday or so that may change. It is going to depend how close the storm’s center comes to Texas as most of the heavy rainfall should be near the center, and on the eastern half of its circulation.

Because of the track uncertainty, the entire Texas and Louisiana coasts need to be paying close attention to the potential for heavy rainfall next week. We don’t have to tell you about the potential for mischief from slow-moving tropical systems. But with that said, we are still very much in the wait-and-see mode with this system—the greatest likelihood is that the Houston area sees a few inches of rain next week, not a dozen or more.

GFS ensemble model forecast for precipitation through Thursday, September 24.

Given that this system is likely to exist for at least the next several days we also have concerns about high tides. Coastal tides are already running about 2 feet above normal, and by this weekend may reach 4 to 5 feet above normal, which will pose problems in low-lying areas along the Gulf of Mexico and Galveston Bay. This is our largest concern after the potential for heavy rainfall.

Matt will have our next update on Friday morning by 7:30am CT.

Tracking a cool front, and a developing tropical system in the Gulf

Good morning. We’re continuing to anticipate the arrival of a cool front late on Friday or Saturday morning, which should make for a rather pleasant early fall weekend across the region. It won’t exactly be cold, but it sure will be less humid. Meanwhile, we’re also anticipating the formation of a tropical storm or depression in the Southern Gulf of Mexico fairly soon—this will have to be watched closely but the forecast for now mostly keeps inclement weather out of the Houston region. More on this below.

Thursday

The really hot weather is almost over, we promise. And it has been hot. Both Hobby Airport and Galveston again tied heat records on Wednesday with highs of 96 degrees. Temperatures should be about 5 degrees cooler today with partly cloudy skies, and rain chances of 30 percent or so. These rain chances will be driven by an upper-level low pressure system and enhanced by daytime heating. Low temperatures tonight will be in the mid-70s for most.

Friday and Friday night

Friday should be similar to Thursday in terms of sensible weather, but things should begin to change late Friday night or Saturday morning. As Matt wrote yesterday, this will not be a knock-you-off-your-feet front blowing in from the northwest, but rather over the weekend we’ll gradually see drier air moving in. This should become noticeable on Saturday morning.

Temperature change forecast for Saturday morning, at 3am CT, shows cooler air moving in. (Weather Bell)

Saturday and Sunday

This will leave us with a pleasant weekend. Right now I’d peg highs in the upper 80s, with mostly sunny skies, for most of us. With lower dewpoints, these temperatures will feel much more comfortable. Low temperatures should get into the mid- to upper-60s on Saturday and Sunday mornings, except for the coast, which will stay a bit warmer. So clearly not cold, but after months and months of summer, the difference in humidity will be notable. Enjoy this taste of fall for a few days Houston, you’ve earned it.

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Friday front still on the way, keeping Gulf tropical shenanigans away from us for now

We’ve got a lot of moving parts in the forecast for the next week or so, with each one helping shape what the next one will do. The first big item is our late week front, which seems to be on track. The second item is the tropical disturbance off Mexico that many of you have expressed interest or concerns in, so we’ll explain how those two interact and what it could mean.

Today

Wednesday should be a sunny, hot day. We should see at least a few showers and storms crop up, perhaps more likely north and west of Houston. But I think most of us will be dry. Look for highs in the low- to mid-90s area-wide.

Thursday

For tomorrow, a disturbance in the upper atmosphere is going to approach southeast Texas. We should see more cloud cover Thursday, and we may even have showers in the area by sunrise. As the day goes on, we’ll call it partly to mostly cloudy with scattered thunderstorms developing. After a morning low in the muggy 70s, look for highs in the low-90s or a touch cooler north and west.

Friday to Sunday and cold front

Last week’s cold front was an “in your face” type of frontal passage, where once the front passed your backyard, you knew it was there. I’m not sure this next front will be quite like that. Look for perhaps some showers Thursday night and Friday morning. They’ll drop south on Friday and any more organized storms should focus south of I-10 to the coast before dissipating late. The front itself will lag a bit, but it is expected to pass the northern half of the area Friday morning and afternoon, and it should eventually reach the coast by Friday night or early Saturday. Instead of a sharp change, we will likely see a gradual drop in humidity and clearing later Friday into Saturday.

Yes, Saturday morning should see low temperatures in the 60s away from the city and the coast. (Weather Bell)

Look for Friday morning lows in the 70s still, followed by highs near 90° Friday afternoon. Then on Saturday, look for morning lows in the 60s in suburbs and outlying parts of the area to around 70 in Houston and mid- to upper-70s along the coast. Sunday morning should be similar.

Both Saturday and Sunday look like fine early autumn or late summer days with ample sunshine. A few morning clouds are possible Saturday south of Houston. We will still see highs in the upper-80s to near 90°, but the humidity will be tolerable.

Can the front fail? It’s plausible that the front doesn’t push quite as aggressively offshore, but trends since yesterday have been toward a slightly stronger push and the front basically dissolving 100 to 200 miles offshore. So we think that this is real.

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Eye on the Tropics: No Vacancy

The Atlantic is full. No room at the inn, folks. We’re fresh out of vacancy. If only that were true. Since our last tropical update last Tuesday, we’ve added <checks notes> three more storms. We’re running about three weeks ahead of 2005’s pace and the last name on the list is Wilfred before we shift over to the Greek alphabet. You can argue all day about how many of the storms have been minimal, but a storm is a storm and 2020 is certainly in a unique place based on our historical records. Incidentally, if you want to look back at an interesting analog year to this one, check out 1971.

It was also a year full of mostly minor to moderate storms, including Fern in South Texas and Edith near Cameron, LA. But it included six active systems (including Fern & Edith) at once with one additional in the pipeline. Ginger on that map above is noteworthy for being the longest lived modern Atlantic tropical system. It lasted from September 10th through October 7th, before eventually reaching land in North Carolina. That track map is something to behold. Even better, it was drawn by local hurricane legend Neil Frank.

At present, we are monitoring four systems, none of which are a concern for Houston. There are also two “invests,” neither of which are a serious concern for us either. Plus, we have one “untagged” Gulf disturbance.

There are four active storms, two “invest” areas, and one Gulf disturbance that we’re watching in the Atlantic this week. (Weathernerds.org)

We’ll do our best to sift through the morass for you, starting with that current lineup of storms and then talking the hypothetical systems.

Hurricane Sally

Eric covered Sally earlier today, and not much has changed. Sally remains a category 1 storm with 85 mph winds. It is going to meander just offshore of the Gulf for the next day or so before beginning to move along north and northeast. Water trumps wind in terms of greatest threats with Sally, as persistent onshore flow will keep coastal areas inundated for awhile.

Sally is going to slowly advance north and eventually pick up a little speed as it moves inland, but it will deliver severe flooding to parts of the South. (NOAA)

Meanwhile, heavy rainfall will repeatedly pelt southern Mississippi, Alabama, the Florida Panhandle, and eventually Georgia and the Carolinas leading to widespread and potentially severe flash flooding.

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