Matt Lanza

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.

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.

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.

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.

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.

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.

Well, I was hopeful that maybe we could identify a period over the next several days that didn’t look unsettled. While it isn’t going to rain everywhere the entire weekend, the chance of rain is going to be higher than usual everywhere from tonight through Tuesday or Wednesday of next week. We will walk you through things as best we can today, and we’ll conclude our Friday post with an update on Tropical Storm Elsa.

How much rain through next week?

We’ll start off today’s post by addressing the question most people probably have: How much rain are we expecting, and will it flood? Rainfall totals are going to vary widely from location to location, but we’re confident that most places should 2 to 4 inches through Wednesday. That said, given significant amounts of atmospheric moisture (high precipitable water, or PWATs), any storms will be capable of producing 1 to 3 inch per hour rainfall rates. So it’s pretty obvious that some locations will see a good bit more than 4 inches over the coming days. Where exactly those locations are is to be determined.

But as you can see from the map above, the current bullseye is just east of Houston. For those curious, the European model has its bullseye over the Sabine River, and the GFS does not really have a bullseye. But most models are in good agreement with this forecast above. You can expect a good bit of rain in the coming days.

Will it flood? This question is somewhat thornier. At this point we don’t expect significant flooding, but the reality is that we can’t rule out things getting a little dicey in spots at times. Even though there will likely be street flooding in spots at times, we are not yet going to trigger the Space City Weather Flood Scale. I do think at some point between now and Wednesday we are going to have to give in with a Stage 1 or 2 type event possible. Things can change, so stay with us through the holiday weekend, and make sure you have downloaded our app!

Today

Friday is going to start off fine. Look for sunshine and a few clouds. Today will probably be pretty hot, with highs in the mid-90s likely. I wouldn’t expect much worse than a couple hit or miss showers through 3 PM at this point. After 3 PM, a cold front begins to sag south into northern parts of the area, and we should see more organized storms break out along or north of Highway 105, dropping into Hempstead, Magnolia, The Woodlands, and Liberty this evening.

Tonight & Saturday

Those storms will continue pressing south after dark, reaching I-10 around or just before midnight, although they could weaken some. A few additional scattered storms will be possible overnight.

On Saturday, we get a surge of moisture (near-record PWATs for the date) that should allow for numerous showers and storms to break out across the region. I would expect a bit of atmospheric “bumper cars” to ensue tomorrow as boundaries collide, popping off new storms across the area in a chain reaction of sorts.

Showers could push or focus south of Houston tomorrow late day or evening.

Temperatures will be held down with clouds and rain. Look for lows in the 70s and highs in the mid-80s.

Sunday

Expect numerous showers and thunderstorms throughout Independence Day, with locally heavy rain possible. Highs will be in the 80s.

What to do about fireworks displays? Well, I wouldn’t be cancelling anything just yet. We are certainly talking up a wet weekend here, and the cancellation option is a very plausible one in some places. That said, there is a good chance that some parts of the area will be just fine for fireworks displays, albeit with some soggy ground to watch from. That decision should be as close to a game time one as possible.

Monday & Tuesday

It’s a bit of a tough call as to which day from Saturday through Wednesday has the best chance for the heaviest rain, but if I were a betting man, I might lay a few chips on Monday or Tuesday. We get a boost in moisture on those days, especially Tuesday and some pretty vigorous upper level support for rain too. Not everyone will see their heaviest rain early next week, but I think some people will, and this is where I would begin to perhaps be more mindful of flash flooding risks.

High temperatures will be held down here. Look for mid-80s at best (probably low-80s or even cooler in spots) for highs and 70s for lows.

Wednesday & Thursday

For the middle of next week, we currently expect to see things begin to wind down a bit. Expect scattered thunderstorms on Wednesday, but we are hopeful that the coverage will be noticeably less than it was on Monday and Tuesday. By Thursday, much will depend on what Tropical Storm Elsa does, but assuming it stays well east of us as forecast, we would probably just see sun, clouds, some isolated to scattered storms (unrelated to Elsa) and slightly warmer temperatures. We’ll see. But it appears that the pattern may begin to change back to a more typical summer one by late next week.

Tropical Storm Elsa

(Editor’s Note: Elsa was upgraded to a hurricane immediately after publication) Elsa did some work overnight getting better organized as it approaches Barbados and the southern Leeward Islands today. Max winds are now 60 mph, and although the National Hurricane Center forecast currently falls just short of Elsa becoming the season’s first hurricane, there is some chance it could attain that intensity.

The forecast right now is officially comfortably east of our area, with a focus on Florida by Wednesday or Thursday of next week. There is still a very wide spread of options available to Elsa beyond day 3 or so, meaning that folks from Central Louisiana through the Bahamas, including all of Florida should still be monitoring Elsa’s progress closely. We continue to think this won’t be a direct issue for Texas, but we will monitor its progress and any track forecast changes through the weekend anyway.

Welcome to another edition of our weekly tropical outlook. The last two hurricane seasons have been full of many quick developing, lower-end storms. Some folks deride the National Hurricane Center for “wasting time” naming these things, but if it looks like a duck and quacks like a duck, whether bloated, thin, short, tall, round, square, or what, it’s still a duck. And that’s why we have added another storm since last week.

If you blinked, you might have missed Tropical Storm Danny yesterday, but it formed off the coast of South Carolina, made landfall and weakened to a depression within about 12 to 18 hours. It wasn’t quite like Imelda, and its fast forward motion will keep it from becoming a Carolina or Georgia version of Imelda, but it went quickly, and it came from an area I didn’t even mention a week ago. So go the tropics.

Tropical outlook in a sentence

While there is one area in the Atlantic for us to monitor, it will likely face an uphill battle to make it to the Gulf in a position to develop any more significantly.

Invest 95L

The area people have been watching a good bit since last week is Invest 95L, which today does not pose much risk of making it to the Gulf. It will likely either stay disorganized and continue across the Caribbean (where it will face mountains of shear) or it will develop a little and get pulled north toward the Bahamas, Florida, or Eastern Gulf. Colloquially, some of us in meteorology will use the phrase “weaker, wester” to describe these things. It seems highly unlikely that 95L makes it to Houston. The National Hurricane Center has just lowered odds of development risk on 95L to 30 percent over the next 5 days.

Invest 97L

The one area I want to focus on is the new Invest 97L, which now has a 40 percent chance of developing over the next 5 days according to the National Hurricane Center (up from 20 percent this morning).

As you can see on satellite above, Invest 97L has some loose thunderstorm activity, but it is not yet organized. The one thing about Tropical Storm Danny: Say what you will about it being “pathetic” or whatever, but at least it had that swirly cinnamon bun look going for it yesterday. 97L is not there yet.

Invest 97L will be steered west or west-northwest around the periphery of high pressure in the Atlantic. Both key operational models, the Euro and GFS tend to buy into Invest 97L developing over the next three days. However, they differ significantly on *how* much development occurs. I’ve plotted the GFS and European models below, showing you what we call 850 mb vorticity. What? That’s a good map to look at to gauge where things stand with potential development risk. And you can indeed see both the GFS & Euro show ample “spin” (yellow & orange) and low pressure near the entrance to the Caribbean on Friday morning, with the Euro on the left and the GFS on the right.

The difference is that the GFS is far, far more aggressive in organizing Invest 97L over the next 3 days. Why does this matter? Because the GFS has been the only model showing this coming to the Gulf as a significant storm. If it’s unrealistically strong 3 days from now, that doesn’t bode well for its accuracy on days 7 to 10. So right now, using context clues, there is a good shot we see the potential for a tropical depression or storm approaching the southern Lesser Antilles by the end of this week.

From there, this will have a mountain to overcome. The Caribbean is full of shear, and any system will not be greeted by favorable conditions on the other side of the islands. While the GFS keeps this going somewhat across the Caribbean, the Euro rips it to shreds. Neither model’s ensemble is particularly bullish on this system’s future either. So sitting here on Tuesday, I find it difficult to think that Invest 97L will make it to Texas as an organized tropical entity.

That said, the weather pattern over Texas is likely to say fairly cool and wet for most of the next 2 weeks. It gets tough to think that a tropical system makes it here as an organized system, but a bigger risk could be that the moisture gets here and exacerbates an already wet Texas.

That’s a wet Texas to say the least. So the bottom line is that we’ll want to sort of watch this system for its moisture. But at least at this point there’s no reason to think it’s going to become a problem for us, and I can’t point you to any reliable, outlier model guidance that says it will. We will let you know if that were to change.

Beyond this, expect a quieter tropics for a little while, as the atmospheric background signals (what we often call the “intraseasonal phase” of the atmosphere) is fairly suppressed over the Atlantic basin, meaning it will inhibit storm formation. That doesn’t mean we won’t see a storm or two, but in general, storm development risk should be lower than it has been. This could allow for our first significant Saharan dust event of the summer as well sometime in mid-July. We will see.