Matt Lanza

Rain mostly offshore this morning, but a couple more days of storms around Houston

We’ve had quite a 12 hours of storms across the region, particularly from just north of I-10 south to the coast, with some impressive lightning and heavy rainfall. The highest 24 hour total I can find on the Harris County Food Control website is just a hair over 3 inches of rain near Dickinson. Radar estimated rainfall from the last 24 hours is shown here.

Rainfall estimates on radar since yesterday show that areas south and east of Houston hit the jackpot. (NOAA)

This morning’s radar snapshot below shows the bulk of the rainfall hugging the immediate coast, with the heaviest mostly offshore at this time.

The heaviest rain is mostly offshore now, with the exception of the Matagorda Bay area, where heavy rain was between Freeport and Palacios just after 6 AM (NOAA)

So, what’s next?

Today

Often, when we see this sort of cluster of rain offshore, it helps to cut off moisture inflow from the Gulf of Mexico. In other words, significant moisture is involved with the offshore rain, and it could help reduce rain chances on land a bit, especially the first half of today. That doesn’t mean it will be totally dry, but showers should be very isolated this morning for the most part.

As the day wears on and daytime heating takes over and presumably we see offshore rains weaken a bit, look for a few more storms over Houston and other inland locations. But today’s rain and storms will probably be more hit and miss than widespread, and odds may favor you avoiding rain. We’ll see how that goes. As someone flying to Houston in just a bit, I am okay with this.

Other than rain chances, expect clouds and sun. Highs will probably approach 90 degrees.

Wednesday and Thursday

Look for afternoon showers and thunderstorms, driven mostly by daytime heating and the sea breeze for the middle of the week. Not everyone will see storms, but those that do could easily see an inch or two of rain between both days. The overall pattern will stay pretty unsettled on both days, but it’s tough to get too cute with details today. We will know more tomorrow morning. Highs should be in the upper-80s with lows in the 70s.

Friday and weekend

The storm system in the upper atmosphere that will help the midweek period be so unsettled will continue working back to the west Friday, into West Texas. By Sunday, it ends up in Arizona (good news for the drought plagued West), so things should begin to really settle down around here this weekend. With more sun, that means more heat, and high temperatures should go from the low to mid-90s to mid to upper-90s as the weekend progresses. Rain chances are never zero in summer here, but they look to be quite low. We’re coming up on our hottest time of the year, so this isn’t too surprising. But still, be ready.

In addition to all that, it’s likely we’ll be seeing another blast of Saharan dust this weekend.

Saharan dust (purple) is going to blast ashore in Texas this weekend, coinciding with high heat. (NASA via Weather Bell)

It’s going to look, feel, and taste like high summer around Southeast Texas.

There are signs this very hot, drier weather will continue well into next week. If you’ve managed to keep the sprinklers off most of this summer, that may change next week.

Due to travel and work for both Eric and myself, we’ll be foregoing our tropical post today, but there’s honestly not much to discuss right now. The tropics remain quiet, and that should continue for at least another week or so. Things may change heading into August, as they often do, but for now we have nothing in particular to discuss. We will let you know when that changes.

Eye on the Tropics: Quiet for a bit

After a frenetic start to the 2021 Atlantic hurricane season, we’re settling down into a bit of a quiet period, and I am sure no one is complaining. Last week saw Elsa, which was the earliest “E” storm on record. We’ve already fallen off 2020’s insane pace however, as Fay formed on July 9th last year. Gonzalo did not form until the 22nd of July, indicating that we had a bit of a lull last year too.

Tropical outlook in a sentence

The next 7 to 10 days are not currently expected to produce any organized tropical systems of note anywhere in the Atlantic Basin.

So what’s next?

I thought I would keep this post fairly brief this week. Looking at satellite across the Atlantic, there just isn’t much happening right now.

The Atlantic basin has a couple minor tropical waves but nothing that will significantly develop. (College of DuPage)

The National Hurricane Center is tagging that one system off the coast of New Jersey for a 10 percent chance of development, but, yeah. Moving on.

In addition to a lack of any beefy tropical waves, the Atlantic basin is choked in dust at the moment. Dust doesn’t prevent tropical systems from forming, but it does indicate the presence of drier air, which usually inhibits storms.

Anywhere you see yellow, orange, or red color, it indicates dust or dry air. The Atlantic is full of it. (University of Wisconsin)

We are basically in peak dust season now, as is typical, so this is not terribly surprising.

On top of all that, if you look out in fantasyland on the GFS or European models and ensembles, you can’t even scrounge up some make-believe activity. Even the usually turbocharged Canadian ensemble only has one or two members showing minimal systems in the Atlantic over the next 2 weeks. So it’s quiet, and model agreement is strong for that. Without going into too much detail here, this is true for good reason: The background environment over the Gulf, Caribbean, and Atlantic is not favorable for tropical development right now or over the next 10-plus days. What is happening in the background is helping to “suppress” thunderstorm development a bit. That doesn’t mean something can’t spin up, but the overall base state of things right now is hostile toward tropical systems, which is good news for all of us.

This may change in the final days of July and first few days of August, so I do expect we’ll have something to talk about when you see this post on July 27th (due to schedules we won’t be posting next Tuesday). But there is no sign of anything right now.

Where activity is busy is in the Eastern Pacific. There are two areas of high probability development over the next 5 days, and there may be more to follow beyond that.

While the Atlantic is quiet, there will likely be a handful of substantial systems in the East Pacific. None are a threat to land for now, and none are expected to reach Hawaii at this time. (Weathernerds.org)

Everything is currently projected to head out into the open ocean, away from Mexico, and not reach Hawaii so that is also good news.

That’ll do it for this week. Hopefully our next tropical post is equally quiet!

Some street flooding possible in spots for the Friday morning commute; drier weather for Houston this weekend

Well, the rains of last night didn’t get going until very late in any organized capacity. So the significant flooding feared last night southwest of Houston never materialized. That’s good news for sure. But that has changed this morning.

This morning

We have a pretty healthy area of rainfall this morning that extends from The Woodlands south to the coast. This started south of the area and has migrated north, and flood advisories are posted for Brazoria County, Brazos Bend State Park, and just east of Bay City in Matagorda County, as of 6:30 A.M. A new flood advisory was just hoisted for most of Houston inside the Beltway, Sugar Land, Kingwood, and Baytown as well. Also, a Flash Flood Warning is in effect for Jackson and Matagorda Counties (west of Bay City) through at least 9:30 AM.

As of 6:30 A.M., areas of heavy rain are lifting north across much of the area, most heavily concentrated southwest of the city. (RadarScope)

Rainfall is occurring right now at the rate of 2 to 3 inches an hour at its worst. Things are moving enough to keep the heaviest rain from falling over the same area for long enough to cause serious problems, but with wide areas of heavy rainfall around, it would seem that some street flooding is going to be likely in spots this morning, especially in the western half of the metro area. Additionally, heavy rain is clobbering western Matagorda County this morning, so folks down there and into Wharton County should expect areas of flooding over the next few hours. That particular area of rain may also get into Fort Bend County later this morning as well, so please be on the lookout for areas of street flooding.

The rain is all lifting generally due north, with some “noise” within the overall rain. This should prevent the heaviest rain from settling over any one area for too, too long. Still, it will likely be enough for some street flooding in spots. (College of DuPage)

Everything is moving generally due north. Again, this setup should prevent any one area from seeing so much rain at one time to cause serious problems. We are going to refrain from invoking the Space City Weather Flood Scale this morning for that reason (and given a few radar trends here late). This is a ripe street flooding setup for scattered areas, but it shouldn’t be too out of the ordinary for us. Just please use caution and give yourself extra time if you are commuting or you must be out and about this morning.

Eric or I will have another update on the rainfall situation before Noon today.

Rest of today

Look for this mess to gradually begin to wind down. The rain may actually not so much exit as “thin out” in place today. Coverage of showers will probably diminish beginning early to mid-afternoon and by evening, just some isolated downpours should be expected. Highs will likely be in the 80s for most spots.

Total rainfall between now and evening will be 1 to 3 inches on average, with some smaller, highly localized areas perhaps seeing as much as 4 to 6 inches, especially southwest of Houston and Sugar Land. Areas east of Houston and down toward Galveston may see a bit less total rain.

Saturday

The good news is that the weekend should see things begin to finally unwind a bit over Texas. This doesn’t mean bone dry every day, but this does mean that showers will ease back appreciably and we should return to some element of “normal summer.” We will go from widespread showers and storms like we’ve been having to more scattered showers and storms tomorrow. Look for highs near 90° after morning lows in the 70s.

Sunday

There is a chance that the vast majority of the area stays dry on Sunday. It will probably be sunny and hot and humid, with highs back up into the low-90s. Sea breeze showers may be the only game in town and those may even be a bit spotty. The best chance for anything organized will likely be north of Huntsville as yet another front drops into Texas Sunday afternoon.

Next week

Sunday’s cold front will try to nudge closer to our area Monday, which means we should see more numerous showers and storms. This will be especially true north of I-10 I think. So be prepared for a wet start to the week. Fortunately, that front pretty much washes out over the state to our north by Tuesday, meaning we can resume “typical summer” for most of next week. I would expect sun, clouds, low-90s by day, mid to upper-70s by night, and the requisite 20 to 40 percent coverage of showers each afternoon with daytime heating and the sea breeze. Days with less rain coverage could be a little hotter, days with more a little cooler.

The tropics look quiet Gulf and Atlantic-wide for the next 7 to 10 days. Our first real Saharan dust event of the season may occur Monday and Tuesday, so be on the lookout for that. Additional dust may arrive late next week. We’ll update you more on Tuesday when our weekly Eye on the Tropics series resumes.

Significant rain southwest of Houston tonight toward Matagorda Bay

Eric and I just want to provide a quick update on the situation that is expected to evolve tonight southwest of the Houston metro area. There have been a few things that have come together today to lead us to think a significant thump of rain is possible in the Matagorda Bay area, extending into Wharton and possibly southern Fort Bend and Brazoria Counties at times. For the vast majority of the Houston metro area, periods of rain are expected, some of which could be heavy, especially in the southern half of the metro area. But serious, widespread flooding is not a concern for us at this time.

How much rain is expected?

As of right now, the thinking is that a general 4 to 8 inches of rain will fall between this evening and tomorrow morning for those areas in Matagorda, Wharton, and Jackson Counties.

Rainfall expected between this evening and Friday morning will be significant in the Matagorda Bay area. (Weather Bell)

There are a couple models we utilize for higher resolution in these types of events that are spitting out some pretty hefty totals, in excess of 10 to 15 inches. So in a worst case scenario, we could be talking about some pretty big rain totals down there. Some of the heavier rains could extend into southern Fort Bend, Brazoria, or Colorado Counties. Galveston County could be on the fringe of heavier rain at times also.

Why is this a problem?

Besides the obvious reason that 8 to 10 inches or more is a lot of rain, the area just southwest of the Houston metro is especially vulnerable right now to flash flooding. Gauge data from the Lower Colorado River Authority (LCRA) shows that once you get close to Bay City, 72 hour rainfall totals have been up over 4 to 7 inches.

LCRA rain totals in excess of 7 inches have been reported in the Matagorda Bay area over the last 3 days. (LCRA)

Basically, an area that has seen this much rain already cannot handle 8 to 10 inches or more of it, so flash flooding is very likely to begin quickly as heavy rain falls.

Could the rain forecast change?

Absolutely. Models are pretty locked in on the region of greatest impact tonight (southwest of Houston), but their performance has struggled at times this week. We are dealing with a slow moving non-tropical system that is behaving like a tropical system. There’s inherent uncertainty on the finer details of the forecast, but for the most part we know that heavy rain is likely in spots, primarily southwest of Houston, and that heavy rain should be enough to cause flash flooding down that way.

Is there a chance this shifts to the Houston area?

As noted above, forecasts can change of course. But right now we feel pretty confident that the risk of serious flooding will not expand into the Houston metro area. Modeling is in good agreement on this, the meteorological variables are best aligned for heavy rain to the southwest, and those areas have had much more rain than the Houston metro has over the last 3 days. That doesn’t mean there won’t be periods of heavy rain in spots tonight. That also doesn’t mean that we won’t have any street flooding issues to contend with. Those are possible, as they always are when heavy downpours are forecast. But we do not expect serious, widespread flooding in Houston.

Why no flood scale alert?

This is a little trickier to answer, but basically since we don’t expect more than some nuisance street flooding in the Houston metro area right now, we are holding back the flood scale. At best it would be a Stage 1 for Houston. But for Matagorda, this would be higher than that, so we don’t want to confuse people southwest of Houston, needlessly panic the bulk of our readers in the Houston metro area, or send any kind of mixed message in general.

The bottom line is: Heavy rain is possible anywhere tonight. Street flooding is always a possibility, though we don’t believe it will be a huge deal in Houston. Significant, potentially widespread flooding is possible in Wharton, Jackson, and Matagorda Counties.

How does Friday look?

Without getting into too much detail: Expect scattered showers and thunderstorms, but the overall coverage of the rain should begin to decrease again tomorrow, as previously expected. We will have the latest for you on that in the morning.