In brief: After an extremely warm spell over the last 10 days, some relief arrives this week in the form of a decent front (for September). Helpfully, we’ll also see some rain chances on the rise, although we’re not going to see inches of precipitation. The weekend looks sunny and warm.

Beginning to transition to fall

Houston’s streak of days with temperatures above 95 degrees continued through the weekend as our region’s anomalously warm pattern continued. We may get day number 10 today. However, some relief really is on the way the a cool front arriving on Wednesday, with some decent rain chances, and then cooler weather for the rest of the week. It’s still September, so don’t expect miracles. But daytime highs in the 80s and drier air will make for a nice pattern change for a few days. Another front is possible during the first week of October—so while it won’t feel cool and crisp like fall, we’re definitely entering a pattern during which we’re beginning to transition to fall.

Monday and Tuesday

For the next two days we’re going to be stuck in the cool front waiting room. Highs for most locations should top out in the lower-90s, but some inland locations could reach the mid-90s again. Skies will be mostly sunny. What will change is that increasing atmospheric moisture levels will lead to some decent rain chances. Overall odds will be best for coastal locations, perhaps as high as 50 percent on Tuesday. The likelihood of rain will be lesser for areas further inland.

Wednesday

Some time on Wednesday we should see a line of showers, possibly broken, heralding the arrival of a front. Highs on Wednesday will likely still reach about 90 degrees, with sunny skies following the front’s arrival. Lows on Wednesday night will drop to around 70 degrees in Houston.

Thursday and Friday

These will be a pair of days with high temperatures likely in the mid- to upper-80s for most locations, with sunny skies. Winds from the north will knock dewpoints into the 50s, which will mean the air feels much drier and the mornings and evenings will be quite pleasant. Low temperatures will fall into the mid- to upper-60s for most locations. This is the way of these September fronts—they tease us with fall, they never last long, but after a long summer even a modest change feels great.

Saturday and Sunday

The weekend should be warm and mostly sunny, with rising humidity. I cannot rule out some rain chances, but I’d put them at 10 percent or less, so probably not impactful. Highs will be around 90 degrees on Saturday, and perhaps a tick warmer on Sunday.

Next week

We are likely going back into the low-90s, with sunny skies, for the first half of next week. However, there is a decent amount of support for another front by next Wednesday or Thursday. Please just pencil this one in, however, as it’s still not a sure thing.

Tropics

A tropical system is likely to move into the Gulf of Mexico on Wednesday, and it may strike Florida by as early as Thursday evening. It poses no threat to Texas. However, I am increasingly concerned about this becoming a powerful hurricane in the very warm eastern Gulf of Mexico. We’ll have continuing coverage of its development and impacts on The Eyewall.

As for what’s next for Texas and the tropics, be sure and check Space City Weather tomorrow for an update on that.

In brief: Although a tropical system that will develop in the Gulf of Mexico this week poses no threat to Texas, we’ve been receiving a lot of questions about it on Space City Weather. So we’re sharing this update from The Eyewall in order to tell Texas readers they have nothing to worry about. It’s likely a different story for Florida, however.

The state of the tropical system

We’ve been talking about the potential for a tropical storm to form in the northwest Caribbean Sea for days, and for the time being there’s still not much to look at on satellite. We’re still seeing disorganized showers and thunderstorms in the western Caribbean Sea, in the vicinity of Nicaragua. However, what has changed is that the models we trust the most are now pointing to a more or less similar outcome over the coming week. That is, we expect a tropical system to develop, and then move into the southeastern Gulf of Mexico by around Wednesday. And after that? Well, that’s what the rest of this post will discuss.

Track of the storm

All of our major model guidance now suggests that a tropical system will start to become better organized by Tuesday or Wednesday, with a center of low pressure forming near Cancun, Mexico, or the western tip of the island of Cuba. There is still some discrepancy in the timing and intensity, but we can have pretty high confidence in this outcome.

The timing of this does matter, as a more rapidly developing storm would likely ultimately track further to the east, which is to say toward the west coast of Florida; and a slower developing system has a better chance of going more due north, ultimately making landfall somewhere between the Louisiana delta and Florida panhandle.

If we look at the 06z run of the European ensemble model above, we can get a sense of the most likely locations where the center of this storm could go. Note that this forecast indicates a potential landfall on Friday, but depending on the forward speed of this system, we cannot rule out a tropical storm or hurricane reaching the coast as early as Thursday.

The other global model ensembles are not dissimilar to the European model shown above. Our best high resolution, operational models are starting to coalesce around a landfall somewhere between Destin, Florida, and Cedar Key, Florida. However given that a center of circulation has not formed, overall confidence in where precisely this storm will go about five days from now is necessarily low.

The most important message I want to leave readers with today is that residents of the Gulf coast from southeastern Louisiana all the way to Fort Myers, Florida, should be keeping tabs on this system over the next couple of days.

As a space guy, I’m also watching closely for impacts to NASA’s Crew-9 launch from Cape Canaveral, Florida, presently scheduled for Thursday afternoon.

What about its intensity?

Forecasting the intensity of a tropical system, of course, often more dicey than a track forecast. Because the storm has not been designated an “area of investigation,” or Invest, we do not have access to a suite of tropical-based models that are used to forecast intensity. So far the global models have been all over the place, ranging from tropical storms to a fairly powerful hurricane. However, these models typically do a poor job with intensity.

From a big picture standpoint, what concerns us here at The Eyewall is that there are no obvious things to slow this storm down. If it does start to develop a low pressure center by around Tuesday or Wednesday, then it would have two full days over the Eastern Gulf of Mexico to intensify, and if conditions are right that offers plenty of time to blow up into a powerful hurricane.

The sea surface temperatures in the vicinity of where this system should track are incredibly warm. This is partly because it is late September, and partly because of the background signal of climate change that has pushed oceanic temperatures, generally, to record highs. In addition, when we look at conditions beneath the surface, oceanic heat content is very high. This means that, as a storm churns north across the Gulf of Mexico, it will not necessarily be bringing cooler water to the surface. Deep oceanic heat is often a precursor to rapid intensification.

Wind shear has been fairly high over the eastern Gulf of Mexico over the last several days, but this shear level is now trending lower. And if this pattern continues as expected, the environment for storm formation and strengthening should be neutral in terms of wind shear, if not even favorable. So we cannot really count on shear for assistance.

Perhaps dry air, particularly on the western flank of the storm, may play a role in inhibiting some development. However, when we stack up the extremely warm surface temperatures in the eastern Gulf of Mexico, and the shear environment, I have to believe that a hurricane is likely to form before landfall late this week. This is another reason for residents of the northern Gulf of Mexico and Florida to keep a close tab on things.

Some final thoughts

It’s still too early to say too much about impacts from this system. However, storm surge, wind damage, and inland flooding from rainfall are all on the table. Where these occur, of course, remains highly dependent upon the track.

Given the current trends, it is unlikely that we see a named storm develop before Tuesday or Wednesday. Waiting for a named storm, therefore, will not leave much time for preparation. Again, this is why we’re advising residents to keep a close eye on things over the next couple of days.

In brief: After enduring one of the longest, strongest late season heat waves on record in Houston, we will begin to slowly reduce heat after today and tomorrow. Look for slightly “less hot” weather next week and an opportunity at a weak cool front. We’re also watching the tropics but are not currently too worried about what develops near the Yucatan as it pertains to Houston.

We hit 98 degrees yesterday officially in Houston, our seventh straight day above 95 degrees that began on September 13th. In the history of Houston’s weather records back to the 1880s, a one week stretch above 95 degrees has not ever occurred after September 13th. We had a couple five day stretches back in 2011 and late last September but never a week. If you’re like me and hate September because it only teases and never delivers autumn in any lengthy fashion, then this stretch of weather inspires much loathing. It’s just that it hasn’t been this hot for this long this late in the season before in Houston. We may make a run at an eighth straight day of this today, but the good news is that change is on the horizon.

Today through Sunday

Today and tomorrow should be similar in nature, with highs generally in the mid-90s, give or take, with limited rain chances. We will probably get the same out of Sunday, though it may be a degree or two cooler. It should still be above 90 though. Morning lows should be stable, generally in the mid-70s. If you’re out for a morning walk, it’ll really depend on exactly when you step outside. Either way, it will be quite humid.

Next week

I get the sense that next week is the week we really start to transition to autumn. It won’t be cool and refreshing by any means, but we will see high temperatures shave off a degree or two each day. We’ll start the week on Monday likely in the low-90s and finish the week in the upper-80s. Morning lows will go from the mid-70s Monday to the low-70s by Friday.

The Weather Prediction Center’s forecast map for next Wednesday does show a cold front pushing into our area. This won’t be a sudden ultra-refreshing change, but I think this will reinforce this idea of a slow drift back toward “less hot” weather next week. With high humidity early in the week and an approaching front there will be a slight chance of showers each day, especially south and east of Houston. But meaningful rain seems unlikely next week.

Tropics

Yesterday evening I pushed a post out at our companion site, The Eyewall to discuss the latest on the Caribbean disturbance we expect to try to develop next week. In the post, I included a section about Texas and why I don’t believe this one is our storm. Meteorologically, the setup is such that whatever it becomes should move very slowly in the southern Gulf or near the Yucatan for several days before eventually getting scooped up by a trough in the Eastern U.S. and whisked off to the northeast. Overnight modeling did nothing to dispel that thinking on my end, so I’ll refer you to the post yesterday to get a better understanding of why we’re not currently too worried. That said, we’ll keep monitoring things this weekend and have the latest for you on Monday, assuming this remains likely to stay away. We will also update The Eyewall this weekend with more. For those of you with travel plans next weekend in that region, you’ll want to keep tuned in.

In brief: Houston’s weather should begin to cool off slightly after two hot days, and then some real change may arrive next week. We’re still not certain about the timing of one or two fronts, but it does seem probable that relief is eventually coming. We also discuss an area of low pressure in the Caribbean Sea that should eventually become a tropical system.

Thursday and Friday

If you came to this forecast hoping to see some immediate change from the heat we’ve seen of late, you’re out of luck. For the last six days Houston has recorded high temperatures of 96 or 97 degrees at Bush Intercontinental Airport, and that trend is going to continue through the end of the work week. We are looking at high temperatures generally in the mid-90s the next couple of days, with slightly higher readings further inland, and slightly cooler near the coast. Skies will be mostly sunny, winds will be light, and nights warm. We did see some isolated showers pop up near downtown on Wednesday, so while rain chances are very low, they’re not zero. We’re looking at 5 to 10 percent chances of a rogue shower, probably.

Saturday and Sunday

More sunshine, but as high pressure starts to weaken we should see slightly cooler daytime temperatures. Much of the Houston region will probably be in the low- to mid-90s during the daytime, with nighttime temperatures falling into the mid-70s. There is a slight chance of some rain showers near the coast. The bottom line is that if you have weekend plans outdoors, you should be good to go—with proper hydration.

Next week

Here’s where things begin to get a little more interesting. High temperatures will start the week in the lower-90s, but as high pressure backs off even further we’ll see the atmosphere open up a little more to the potential for some rainfall. We’re still probably talking only 20 to 30 percent chances each day, but there will also be some clouds mixed in with the sunshine.

By Thursday or Friday there is a chance that a weak front pushes into the Houston area. At this point it’s difficult to be sure this happen, but my sense is that we’ll see a very slight reduction in temperatures and some slightly lower humidity. A stronger push of cooler and drier air could happen next weekend, which may drop nighttime lows down into the low- to mid-60s. This is far enough out that I don’t have super-high confidence in this scenario, but there is a fair amount of support in the ensembles at this point. Fingers crossed.

Tropics

The National Hurricane Center has increased the likelihood of a tropical depression or storm forming in the Caribbean Sea during the next seven days to 40 percent. This is the area we’ve been talking about for several days now. It’s likely that something will eventually develop, but whether it stays mired in the Bay of Campeche, or eventually lifts north into the Gulf of Mexico remains an open question. Where it goes will, to some extent, be determined by the fronts I discussed above. Matt did a nice job of discussing this uncertainty, and why we just don’t have confidence in any scenario, here. The only thing to do is continue to watch it, and not get fixated on any single model run. They’re still bouncing around like crazy.

Note

I wanted you to know that I’ve got a new book coming out next Tuesday. I’m mentioning it here because I worked really hard to write a compelling tale. REENTRY tells the story behind the story of SpaceX’s Falcon 9 rocket—from its first launches, landings and failures, to ultimate success—as well as the Dragon spacecraft. You can buy the book anywhere, but if you want a signed and personalized copy you’ll need to order from a Houston-based store, Blue Willow Bookshop, by Friday afternoon. Here’s the link.