Matt Lanza

Happy Sunday, everyone. I wanted to dedicate a special post to the tropics today because there’s a lot happening, and we just want to let you know where things stand with each area we’re watching.

Tropical outlook in a sentence

We expect activity to crank up a bit this week, with potential for a named storm or two, but at this time none of these is a direct threat to the Houston area.

Quick overview

As of Sunday afternoon, the National Hurricane Center has four areas highlighted for potential development over the next 5 days.

In addition to these four areas, there are some things in the Gulf to watch but none that are likely to develop tropically. We’ll get to all these areas now. Use the map above as your guide.

Area 1 in the Caribbean

Is this a concern for Texas? Not really, but it may help contribute to some rainfall next weekend or after Labor Day

The main area we’ve been watching for a few days now is a disturbance that’s heading into the northwest Caribbean. The GFS model latched onto this system last week, incorrectly it turns out, and was trying to bring this into the Gulf as a substantial storm on occasional runs. Models seem to have latched onto this now and favor a track that’s a bit farther south and into Mexico. Whether it becomes a system or not remains to be seen.

It certainly has a long way to go based on the satellite image above. Why are we confident in this likely staying to our south? Well, for one it’s disorganized. Weaker systems will be less apt to gain latitude and will continue generally off to the west or west-northwest across the Caribbean. The longer this takes to organize, the narrower that exit ramp becomes until perhaps it’s too late and it ends up being forced into Mexico or even Central America.

Even in the case of the more bullish GFS model, one look at the ensemble tells you all you need to know. Wherever the low is this Saturday evening; be it west of the Yucatan over the Bay of Campeche or just approaching the Yucatan, as high pressure builds across the northern Gulf from Bermuda, it will seal off the northward exit door, and even a stronger system would likely be forced into Mexico here. And again, that’s assuming the GFS is correct on developing this…a bit of a stretch right now.

So, at this point, the only real thing this might do in Texas is bring us some rainfall enhancement later next weekend or just after Labor Day. Obviously, we’ll watch for any changes, but at this point, we have limited concerns regarding this system.

Invest 91L

Is this a concern for Texas? At this time, we do not believe this will impact the western Gulf at all.

Invest 91L is likely to garner most of the headlines this week. It has the highest chance to develop right now, and it’s likely to be the one that comes closest to the U.S. This one is going to be a bit of a challenge to predict I think, as the steering currents around it, and the organization of the system itself will ultimately impact its track and both seem complicated.

In the near-term, this thing has to fight dry air all around it, compounded in part by pretty aggressive wind shear on either side.

Over the next 3 to 5 days, as this comes west and west-northwest to just northeast of the Lesser Antilles, it will then likely start feeling the effects of shifting steering currents. Initially, those steering currents may keep an exit door open for 91L to turn out to sea. But if it’s too weak to gain that much latitude, it will stay in place and may actually get turned a bit back to the west again, bringing it a bit closer to the Bahamas or Florida perhaps. This would be the result of that high pressure shifting west across the northern Gulf that helps keep area 1 away from Texas. It may also cause it to slow down some as well.

From there, it’s anyone’s guess. At this point, I am not expecting anything major from this, but it’s worth watching in the Southeast or the larger Caribbean islands and Bahamas. But any impacts in those locations are at least 6 to 8 days away. Never say never, obviously, but at this point it seems unlikely to get to the Gulf.

Invest 92L

Is this a concern for Texas? No.

The second invest in the Atlantic is chilling east of Bermuda. It’s no threat to any land mass at this time, and any development would be slow and probably weak.

Area 2 in the deep Atlantic

Is this a concern for Texas: Not right now, and probably not at all.

The last area of note from the NHC is in the far eastern Atlantic. Right now, things are a bit of a sloppy mess out there, with storms, tropical waves, and more — but nothing organized.

What exactly happens out here is TBD. Models are convinced something should come of this, but none of the model data looks especially significant at this point. Some even turn this out to sea before it even gets halfway across the Atlantic. Whatever the case, this is so far away and so disorganized right now, that there’s little we can intelligently say about this area. So we’ll leave it at that for now.

The Gulf

As of Sunday afternoon, there are no areas of interest outlined in the Gulf by the NHC. Looking at satellite here, that may be somewhat tough to believe.

That area of thunderstorms looks better than anything in the tropical Atlantic that’s outlined at this time. But looks are sometimes deceptive. While certainly there is a lot of storm activity in the western Gulf, there is no organization to this area right now, nor is there expected to be. This moisture is expected to come north and northwest over the next 36 hours, and this is likely to enhance our coverage of showers and storms tomorrow and perhaps Tuesday, particularly along the coast but perhaps inland as well. We’ll have more on this for you in our usual Monday morning post, but keep your umbrella handy tomorrow.

Aside from that, the Gulf looks quiet. There are modeling hints of something trying to emerge out of Central America after Labor Day, but it’s so far out and has such modest model support right now that it doesn’t make sense to speculate beyond the fact that we’re always monitoring things this time of year. We’re good this week, and we’ll keep tabs on all the things out there as the week progresses. As good a report as you could ask for on August 28th. More for you tomorrow AM!

As Eric covered this morning, we’re watching rain chances here in the Houston area for the midweek period, as some rainfall rates may lead to street flooding in parts of the area, especially north of I-10. But we wanted to also catch you up on what’s happening elsewhere in Texas, as we know many of you travel to and fro or have friends and relatives across the Lone Star State. Here’s a quick rundown of what’s happened and what to expect.

DFW Metroplex flooded

Incredible amounts of rain fell on the Dallas and Fort Worth Metroplex overnight and into today, with some parts of Dallas and Tarrant Counties seeing 12 to 16 inches of rain in 24 hours. DFW Airport is approaching its single day rainfall record, and at worst it will finish as the second wettest day there on record.

Many roadways are flooded, and if they aren’t, they are littered with flooded cars. Travel is discouraged to Dallas or Fort Worth the rest of today. Tomorrow seems like a better day for that, though you may encounter heavy rainfall between Houston and Dallas. So whatever your plans are, please use caution and budget in patience and pad.

City of Dallas rain total map
Tarrant County rain total map

Next round of flooding concerns

For folks in Dallas, the good news is that rain should ease up a lot this evening as the frontal boundary that has helped focus the rains has sagged south of the city. They will have a chance to clean up. Rainfall should begin to pick up in intensity a bit farther south though, and tonight’s focus could be Hill Country or the San Antonio and Austin areas.

In fact, Hill Country and parts of San Antonio, Austin, and Waco are being highlighted by the National Weather Service Weather Prediction Center (WPC) this afternoon for potential 2 to 3 inch hourly rainfall rates.

In addition to this, areas of northeast Texas may be targeted with heavy rainfall as well, and the flooding threat will extend to places like Texarkana and Tyler. Tyler is under a Flash Flood Warning as of this writing. Flood Watches include those locations, down to Lufkin and east past Shreveport, LA.

Look for flood watches and warnings to shift through the week as the rainfall threat shifts.

Tuesday and Wednesday’s risks

Both Tuesday and Wednesday will see rain drop closer to Houston. We aren’t expecting the level of tremendous rain rates and flooding as seen in Dallas, but we’ll want to watch things closely over the next few days, as model precision in handling rain rates through these types of events is rather poor. As of now, the primary risk of flooding rains will extend from just northeast of San Antonio across northern parts of Houston into Louisiana tomorrow.

Then on Wednesday we’ll deal with residual rain chances in Houston and most flooding risks in Louisiana.

Will this end the drought?

Yes and no. Drought is complicated. The amount of rainfall needed to officially end the drought in Texas is 10 to 15 inches over a wide swath of the state. Other than the Dallas area, we aren’t seeing those kinds of totals over a wide enough area.

Drought is a little more complex than just needing a certain amount of rain, however. There are longer-term droughts, like the one Texas is in, which impacts agriculture, deep soil moisture, water supply, etc. Then there is short-term drought, which we also have had this summer. That leads to all of the above but also things like wildfire risk. This rain will absolutely help, if not end the short-term drought in much of eastern Texas. It will help the long-term drought as well, but we will need more rain in the coming weeks in order for that to be effective. I spoke a bit about this on Texas Standard this morning.

Why is this so bad so fast?

There’s a saying that droughts end in floods for a reason. Texas is a state of extremes, becoming further exacerbated in a warming climate. In this case, a persistent weather pattern that plagued us with drought and heat all summer finally flipped, simultaneous to a bunch of added moisture from the Southwest monsoon (which itself may have been energized somewhat by the old tropical disturbance that flooded parts of South Texas over a week ago), as well as added moisture from this weekend’s PTC 4 that went into Mexico. All of this hit a sagging cold front, and someone will get slammed in that instance.

In a timely turn of events, new research has come out showing how dry soil can exacerbate flooding issues with heavy rain. You can read about that here.

The bottom line: Texas has a history of droughts ending with floods. That’s sort of what’s happening here. While this may not necessarily be the “end” of drought for all of Texas, it will be for some of the state. Please use caution and stay aware of rain risks over the next few days as it all moves through.

As Eric has been alluding to all week, things have now changed, and they will continue to do so in a big way for not just Houston but all of Texas. Last evening’s rowdy (and in some cases damaging) storms were the first phase in what will be a much different weather pattern for the rest of the month. The Texas-wide drought is on notice for what should be significant relief.

Today

We’re starting the morning off with some noisy storms south of Houston. The storms are generally moving east, but the overall trend seems to be to build storms back to the north some. None are severe at this point, but there are some special marine warnings on the coast due to 35 to 45 mph wind gusts, or a bit stronger, as well as the potential for waterspouts.

As the day goes on, storms should continue expanding northward and inland. Locally heavy rain is again possible today. Thus far, rates are fairly manageable, but a few spots may need to be watched today for some street flooding. Most of Southeast Texas has been outlined in a marginal (Level 2/4) risk for flash flooding today. As a precaution, we are going to issue a Stage 1 Flood Alert, based on the SCW Flood Scale.

Street flooding is possible anywhere in the area today, but I would watch areas west of Houston that saw 2 to 3 inches of rain yesterday, as well as areas south of Houston, where the heaviest rain is right now. Yes, this is welcome rain to be sure, but some nuisance street flooding feels possible today, especially through early afternoon.

Storms should calm down by evening. Clouds and showers will keep temperatures down today. Highs should only be in the 80s, though if you see sunshine in your location, you could pop above 90, especially north and west of Houston.

Invest 99L & weekend

The weekend forecast will be hit and miss for most folks. At this point, I think both Saturday and Sunday carry a good chance of at least scattered showers or storms, near the coast in the morning, expanding inland during the afternoon. Locally heavy rain is possible, but widespread heavy rain seems unlikely this weekend. Both days should see some sunshine, which will allow us to punch back into the 90s in most spots, with morning lows in the 70s.

Regarding the tropics, the National Hurricane Center continues to highlight the potential for now-classified Invest 99L to become a tropical depression or storm over the next 24 hours before moving inland over Mexico on Saturday.

This should have no direct impact on our weather in the Houston area, but it’s possible that some heavier rains get close to South Texas later in the weekend or early next week.

Next week

I am not going to even try to pin down the specifics of any day next week. What we know is that there will be rain chances every day. Some of the rain could be heavy. Parts of the state are going to see a lot of rain (see below), probably to the north or northwest of the Houston area. Daytime highs will flirt with 90 every day, but days that see more widespread showers or storms will probably stay in the 80s. Humidity will stay high, so nighttime lows well into the 70s are still likely.

Rain totals

So just how much rain will Texas see over the next week or so? The answer is a lot. The current NWS outlook for rainfall across Texas is below and shows as much as 7 to 8 inches in interior Texas, including the DFW area and possibly the Austin and San Antonio areas as well. Higher amounts are possible, as is flooding across the state.

While the Houston area should see a bit less than other parts of the state, there’s still enough uncertainty in the forecast to think we have a chance at higher amounts, especially north and west of the city. Whatever the specifics, this is a big, big drought denter for the entire state of Texas. We’ll keep you posted as needed over the next few days.

After a summer of fishing for things to talk about in each week’s Eye on the Tropics, we’re quickly transitioning into peak season now, with a number of things to discuss. Today’s post will explain one system that should bring us some boosted rain chances heading into the weekend or next week, the chance of activity in the Atlantic, and what the pattern change expected over Texas will mean for us in terms of tropical risks.

Tropical outlook in a sentence

Activity should begin to ramp up this weekend and next week with a possible weak system in the Bay of Campeche, followed up by some additional tropical waves in the pipeline across the Atlantic worth watching.

Bay of Campeche & south Texas

This weekend saw tremendously beneficial rains in far south Texas. There may be more coming but who sees them remains a question. A tropical wave located over the southwest Caribbean is expected to move generally northwest over the next few days.

The National Hurricane Center is giving this about a 20% chance of developing into a depression or storm over the next 2 to 5 days. While a lot of folks will see this and be alarmed, there are reasons to think this system will struggle in terms of organization. For one, while wind shear was low in the Gulf as Invest 98L came crashing ashore on Sunday, wind shear in the western Caribbean and Bay of Campeche is not low. It’s fairly robust, and based on most model data I’ve looked at, some elements of shear are going to persist around this system until it comes ashore. My hope is that this will cap the ceiling on intensity potential.

The other reason not to really worry is that the pattern is going to likely keep it from coming up the Texas coast. It will track toward northern Mexico or the Rio Grande Valley as a disorganized tropical low, depression, or low-end storm. No credible modeling shows anything worse than that right now.

While South Texas saw a heck of a lot of rain from Invest 98L, where the rain falls this time around will be a little trickier to project. If the system can organize some, heavier rain is possible again in South Texas, while scattered storms would impact the Houston area at times. If the system remains rather disorganized, it’s possible that South Texas will see limited rain, but the bulk of the moisture coming from this wave will end up entrained in a cold front stalled over north Texas, bringing heavier rain to the Panhandle, DFW area, and into northern Louisiana and Arkansas. In that case, again Houston would see just scattered storms.

So for now, while I wouldn’t worry about this one specifically, I would continue monitoring it to see how rain chances will evolve.

Atlantic waves

Behind this wave, there are a few others in the deeper Atlantic.

Modeling is showing a lot more noise in the Atlantic from these waves now, meaning more ensemble model members are developing some of them. However, there’s not a whole lot of signal in the noise. That’s both good news and bad news. It’s bad because it doesn’t give us anything to hone in on just yet. So, all we can say is “Hey, the tropics are going to be active in late August.” Bold statement! But it’s good because there’s always a chance that the lack of signal indicates the environment will remain somewhat hostile toward tropical development. We’ll continue watching this to see if there’s anything to latch onto in the coming days, but as of now there’s nothing to hang our hats on.

Does the pattern change mean a change in Texas’s tropics risk?

We’ll close today’s note with a quick comment about the big picture pattern. For most of summer, Texas has been shielded by high pressure over the southern Plains and Central United States. This is why June and July were so hot.

That high pressure system acted to basically keep us hot, dry, and protected from any Gulf threats all season. The pattern is changing now, rather dramatically. The new look will feature high pressure mostly anchored in the northern Rockies or western Canada, as well as near Bermuda, with a rather healthy trough in the Eastern United States.

This means a couple things. For one, we’re no longer really “shielded” from the Gulf. So anything that can get into the Gulf will be apt to gain a bit more latitude than it would have back in June, July, or early August. That certainly doesn’t guarantee that we’re at risk for storms, but it has made us more vulnerable. That said, the other element to this is that the trough in the East *may* act to help “pick up” Atlantic systems more easily. In other words, the stuff coming off Africa may be more likely to get lifted north earlier, which favors either out to sea tracks or up the East Coast tracks. So our focus would probably be less on long-tracking storms from Africa and remain on systems like 98L, this week’s system coming out of the Caribbean, or anything that can spin up on the tail end of old fronts. So, this is a good news/bad news sort of scenario for us. The key points I want you take away from this post today are:

• The tropics are finally coming alive, as is usually the case in late August.
• The main system to watch right now, a tropical wave in the Caribbean, will likely track toward far south Texas or Mexico this weekend and increase our rain chances some.
• Additional waves have the potential to develop farther out in the Atlantic next week, but none looks like a slam dunk just yet.
• The general pattern change we will see in Texas is going to leave us open to local, “homebrew” Gulf threats, but there is a chance that the pattern in the Eastern U.S. will favor deep Atlantic systems turning out to sea or perhaps getting closer to the East Coast.
• With the season ramping up now, it’s time to start checking in once each day or two to see what’s happening and make your final checks on emergency kits and plans while we grind through things into September.

This may or may not be our last weekly post on the tropics, as we may have enough to discuss daily now. Regardless, stay with us for updates on anything of note in the days ahead.