Eric Berger

Good morning. Today marks the autumnal equinox, when the sun shines directly over the equator. Put another way, for the northern hemisphere today is the first day of fall. Alas, it will not feel like fall outside, but rather the dead of summer. In fact, Houston faces five more very hot, August-like days before the first real cool front of the season arrives on Monday, ushering in drier and at least moderately cooler air.

For the last few years we have dubbed the first day it really feels like fall in Houston as FALL DAY. This year that will probably be Tuesday or Wednesday. Along with our partner Reliant Energy, we thought it would be fun to celebrate Fall Day and host our first-ever in-person event with me, Matt, Maria, Lee, and Dwight. Please join us on Sunday, October 2 between 10 a.m. and noon at the Houston Botanic Garden for a fall festive meet-and-greet with activities for kids and adults. Admission is free. Look for more details soon.

Thursday

High pressure will peak over the region today, and accordingly we’re going to see very warm temperatures with highs generally in the upper 90s. A few locations well inland may hit 100 degrees, whereas the coast will reach the low 90s. Skies will be sunny, with rain chances right at zero percent. Winds will be light, generally out of the north, at 5 to 10 mph. Lows tonight will drop into the mid-70s.

Friday

This will be another hot and sunny day, with highs perhaps 1 or 2 degrees lower than Thursday.

Saturday and Sunday

The weekend will see continued hot and sunny conditions, but as the high pressure ridge starts to back off we can expect to see highs dropping into the mid-90s for most of Houston. There is perhaps a slight chance of showers by Sunday afternoon, but I would not bet on it.

Next week

Monday will be hot again, but after then we’re anticipating the arrival of a cold front that will bring drier and cooler air into the region. Days are still going to be plenty warm, with ample sunshine and dry air helping to keep daytime highs in the upper 80s to perhaps 90 degrees. But nights should cool off fairly quickly as the sun goes down, and lows drop into the 60s. With dewpoints in the 40s and 50s for several days it will feel noticeably different. Rain chances stay low.

The tropics

There is a lot going on, including a significant storm headed to Canada in the form of Hurricane Fiona, but for the continental United States all eyes are on a tropical wave known as Invest 98L. The system has yet to show significant organization as it is being affected by strong wind shear, but there is high confidence that this will become a tropical storm, and then probably a hurricane, over the next several days as it moves into the central and the western Caribbean Sea.

After that time there remains some uncertainty on the track forecast as 98L likely turns to the northwest into the Gulf of Mexico. Over the last 24 hours the premiere US forecast model, the Global Forecast System, has brought 98L closer and closer to Texas before it makes landfall in Louisiana about 10 days from now. See below for the latest GFS forecast, which is far enough out that it is probably worthless. I am sharing it for illustration purposes, however.

Under this scenario Invest 98L misses a “trough” that would allow it to move north early next week, and it continues to drift into the central and western Gulf of Mexico before ultimately turning north. In this case we would be watching the system for a long time. While this is certainly possible, at this time I do not consider this a likely outcome.

Why? Because the reality is that the GFS model’s operational run is a significant outlier at this point. The vast majority of model guidance, including many members of the GFS ensembles (shown above) and the European model (shown below), keep 98L in the eastern half of the Gulf of Mexico.

Our confidence in a track forecast should improve during the next 24 to 48 hours as the global models ingest data gathered by hurricane hunters, and the center of Invest 98L starts to form. Until that time expect a fair amount of uncertainty, and we’ll accordingly continue to watch it closely.

Good morning. The season’s first real cool front is on the horizon, but it will be a painful trek to get there. That is because the next six days will bring very hot conditions, including the possibility of 100-degree days, before the arrival of a cooler and drier air later on Monday or Monday night. Rain chances are near zero until the front’s passage.

Wednesday

As high pressure starts to tighten its grip on our weather, highs today will be in the mid- to upper-90s across the region, with sunny skies. Winds will generally be light, out of the north. Lows tonight will drop into the mid-70s under clear skies.

Thursday and Friday

High pressure reaches its peak thickness toward the end of the work week, and as a result these days will bring temperatures in the upper 90s for much of Houston, with 100 degrees possible for inland areas. Some locations probably will set record high temperatures. Expect sunny skies, and light easterly winds, for the most part.

Saturday and Sunday

The ridge starts to back off some this weekend, but we’re still going to be hot and sunny, with highs in the mid- to upper-90s. Some slight rain chances return to the forecast by Sunday afternoon, but they’re probably on the order of 10 or 20 percent.

Next week

We’re still working out the details, but confidence is now pretty high—think, 80 percent or greater—that a cool front will push into the area on Monday, with notably drier air arriving overnight or by Tuesday morning. There is a chance of rain with the front’s passage, but right now it looks pretty low. I’m thinking we’ll see highs in the 80s for a few days next week, with lows perhaps in the low 60s, but we’re still a bit fuzzy on that. Regardless, it’s going to be pretty amazing, I think.

Tropics

The tropics are popping off all over the place. Hurricane Fiona is likely to pass just west of Bermuda and then menace Canada this weekend. Newly formed Tropical Storm Gaston is expectorating all over the northern Atlantic, but is not a threat to much of anything. The system of most interest to us is Invest 98L, shown in red above, which should soon enter the Caribbean Sea.

This storm will very likely become a hurricane in the Caribbean. For us, the big question is what happens next. While it’s not possible to say so with certainty, an eventual turn northward into the Gulf of Mexico about one week from now is the most probable outcome. Those who have read this site for any period of time understand that beyond about seven days weather forecast models become a lot less useful.

Climatologically, this would be late in the season for Texas to be directly impacted by such a storm, and most of the recent modeling guidance keeps the storm over the eastern half of the Gulf of Mexico. Ultimately a lot of factors, including next week’s front, will determine the track of the storm. We’ll keep watching.

Good morning. Houston has one more week of exceptionally hot September weather before the pattern should change, with an increasing likelihood of a decent front pushing into the region. In this post we’ll also discuss the potential for a tropical system to move into the Gulf of Mexico next week.

Tuesday

Temperatures maxed out in the low- to mid-90s across Houston on Monday, and conditions will be similar today under mostly sunny skies. But whereas about 20 percent of the region saw a passing shower or thunderstorm, that number is probably 10 percent today. And if you think that is low, wait until you see the precipitation forecast for the remainder of the week. Winds will be light, out of the east at about 5 mph. Lows tonight should drop into the low 70s.

Wednesday

Look for sunny conditions, and highs in the mid-90s. Rain chances will be near zero.

Thursday and Friday

A ridge of high pressure will reach its peak toward the end of this week, and it’s going to push high temperatures to the upper 90s, and for some inland locations, possibly 100 degrees. This is very late in the year for such hot days. In nearly 150 years of records, the latest 100-degree day ever recorded during the calendar came on September 27, 2005. (Friday is September 23). Rain chances are zero each day, with sunny skies.

Saturday and Sunday

As the aforementioned ridge starts to retreat a bit, we’ll see high temperatures back off slightly. But I’d still anticipate highs in the mid-90s, with sunny skies, on Saturday and Sunday. A few scattered showers and thunderstorms are possible by Sunday, but at this point I’d peg chances at 20 percent or less.

Next week

While the pattern is not yet set in stone, it now appears likely that a cold front will push through on Monday or so of next week, and this should bring some notably drier and cooler air. Don’t expect miracles from the first front of the year, but we should see nighttime temperatures drop into the 60s for inland areas, with dewpoints comfortably in the 50s.

Tropics

Fiona is now a major hurricane pulling northward of the Dominican Republic, and it will affect Turks and Caicos and the southeastern Bahamas today. In a few days, the storm could threaten Bermuda.

Of more interest to the continental United States is a tropical wave in the Atlantic Ocean, a day or two away from entering the Caribbean Sea. Global models have become more bullish on the development of this system during the last 24 hours, and it has a plausible path to reach the Gulf of Mexico in a week or ten days from now. Here’s a map of the European ensembles for this system, one week from today:

There is good agreement here about a tropical system reaching the western Caribbean Sea early next week. Importantly, this is about as far as we can reasonably rely on model guidance. After five to seven days, the accuracy of such models breaks down. And indeed, when we run the forecast forward just two days, to Thursday September 29, there is an extremely wide variance of outcomes. Some of the models start to turn the storm northward toward Florida, and others continue to push it westward toward the Gulf of Mexico, where it could wind up anywhere from Mexico to the Florida peninsula.

So what does all this mean for Texas? We are fast reaching the time of year when it is less likely for storms to track into Texas, but that does not mean it’s impossible. In this case, the models are sending a strong signal that this system will develop in the Caribbean Sea, and become a tropical storm or a hurricane. After that time it may very well move into the Gulf of Mexico, but there are just too many variables to sort out before we can have any confidence in where it will go. Our best forecasting tools are just not up to the task of delineating a clear track for a tropical system that has not yet formed, nine or ten days from now.

Bottom line: If you’re living near the Texas coast, this is not something I would lose too much sleep over. But it’s definitely worth watching, and we’ll be doing just that.

As Matt so accurately wrote on Friday, a “second summer” has descended upon Houston. It will reach its peak this week, and conditions will be pretty brutal for late September, with high temperatures nearing or possibly surpassing 100 degrees. The good news is that we do see a light at the end of the tunnel, with the potential for a decent cold front pushing into Houston next week. This is not something we can guarantee yet, but I would say that if you can hold on for about one more week of Houston summer, we probably should start to transition into more fall-like weather soon.

But yeah, this week is going to be brutal.

Monday

Today will bring more weather like we experienced on Sunday, with mostly sunny skies and highs in the mid-90s for much of the region. We will again see the potential for some isolated to widely scattered showers, with chances only in the 20 percent range for coastal areas, and perhaps 10 percent for inland areas. Winds will be light, out of the east at 5 to 10 mph. Lows tonight drop into the mid-70s.

Tuesday, Wednesday, Thursday, and Friday

The middle of this week will be hot, hot, hot. High pressure will dominate our weather, and this is going to drive temperatures into the upper 90s and possibly 100 degrees for areas well inland. Thursday looks like the hottest day of the week. There is no way to sugarcoat what is going to be anomalously warm, potentially record heat for late September. Rain chances will be near zero after Monday.

Saturday and Sunday

High pressure starts to back off some this weekend, but I think we’ll still be solidly in the mid-90s in terms of temperatures, with mostly sunny skies. Rain chances remain fairly low, but it’s difficult to rule out precipitation this far out.

Next week

Much, but not all, of the model guidance shows a pretty decent cold front arriving in Houston next Monday or Tuesday. This is far enough away that we cannot fully buy into it yet, but at this point I think the chances are better than 50-50. This front has the potential to drop highs into the 80s, and lows into the 60s, and could be strong enough that I’d classify it has Houston’s first “real” front of the season. We should have a more definitive answer on the front in a couple of days, and obviously we’re watching it closely.

Tropics

Hurricane Fiona, with sustained wind speeds of 90 mph, ravaged the island of Puerto Rico this weekend, knocking out power to the entire island and dropping 1 to 2 feet of rain. The US territory will need our help in the weeks ahead. The storm is beginning to turn northwest, affecting the Dominican Republic, and will eventually turn northward and threaten Bermuda.

Beyond Fiona there’s not much to write home about. We are getting close to the end of the Texas hurricane season, but I’m not quite ready to declare it over yet. But soon, probably. Check back Thursday.