Weekend weather outlook improves, but isolated street flooding possible

A few days ago we anticipated that the worst of the rains would hit Houston this weekend. However, that no longer is likely to be the case as the biggest threat has begun to shift east of the Houston metro area over Louisiana. Nevertheless, we are going to maintain our Stage 1 flood alert through Sunday, as it will still be possible for localized areas to see heavy rainfall and some brief street flooding this weekend. But to be clear, most of the Houston region will not experience this.

Rainfall totals on Friday and Friday night. (NOAA)

Friday offers a case in point. Whereas most of Houston saw a few drops or perhaps one-tenth of an inch of rain, communities such as Bacliff, San Leon, and Kemah right along the west side of Galveston Bay saw 6 inches or more, which quickly flooded streets and even a few homes. There is the potential for this kind of isolated storm again today. It’s the classic Houston situation, you know? Some areas will see sunshine and dry roads, and a few miles away storms may be training.

NOAA rain accumulation forecast for now through Tuesday. (Weather Bell)

The bottom line is that you should keep an umbrella handy this weekend. Rain chances are fairly high across the region, although we expect most of you to receive 1 inch or less through Sunday. We’re increasingly confident the heavy rainfall threat will end by Sunday evening, after which we’ll transition to a more summer-like pattern. Unless this forecast changes dramatically, we’ll see you on Monday morning.

Heavy rains still expected this weekend, likely to affect roadways

Strong showers and thunderstorms developed on Wednesday evening, quickly dropping 2 to 3 inches of rain over parts of northeast Houston, near Humble. Other areas of the city also saw briefly strong storms with incredibly loud thunder. We still anticipate this heavy rainfall becoming more widespread this weekend, and due to the potential for street flooding we remain under a Stage 1 flood alert for the entire area.

Thursday

Today will be similar to Wednesday in that the daytime should see a mix of sunshine and clouds, allowing high temperatures to get into the upper 80s. As the temperature rises, we’ll see an increase in rain chances this afternoon. Rains will likely start somewhere near or just south of the Interstate 10 corridor, and then slowly lift north. I suspect a few areas will again see bullseyes of 2 to 3 inches of rain today, with most of the area seeing significantly less. Rain chances get lower after sunset.

Friday

At this point, it looks like conditions will favor more widespread rainfall on Friday, with 0.5 to 1.5 inches for much of the region, and higher isolated totals. Friday begins the period of biggest concern for us with these rains, and it will run through about Monday. As is typical with this kind of system, it can be difficult to predict exactly when and where the heaviest rains are going to fall even a few hours beforehand.

So what is this system? Essentially, a slow-moving upper-level low will move across the mountains of northern Mexico into southern Texas on Friday. Then it will meander across the state, with disturbances rotating counter-clockwise around its base. As it does so, the upper-level low and its associated disturbances will draw the Gulf of Mexico’s ample moisture into the coast, and this will set up a wet pattern that we won’t break out of for several days.

That green blob is the upper-level low on Saturday night, sort of wobbling over south Texas. (Weather Bell)

Saturday, Sunday, and Monday

This setup will generate periods of heavy rainfall along the Texas coast this weekend and into Monday. With access to the Gulf moisture, these storms will be capable of producing rainfall rates of 1 to 3 inches per hour, and this quickly backs up streets. It looks like the peak of activity will come from Saturday afternoon through Sunday morning, but again, confidence with predicting specificity this far out is low. Bottom line: prepare for heavy rain this weekend. We expect widespread accumulations of 4 to 6 inches, with higher localized accumulations. Matt and I will be watching all of this closely to keep you informed.

NOAA rainfall accumulation forecast for Houston through Tuesday. (Weather Bell)

Next week

So when does this mess move on? Rain chances will start to slacken by Tuesday or Wednesday, and we think building high pressure will shut the spigot off by later in the week. Probably. Hopefully.

Looking ahead to a wet weekend for the Houston metro area

Good morning. The radar is quiet across the region, and likely will remain so this morning. However, the overall pattern remains favorable for rainfall this week, likely culminating in widespread showers and heavy rainfall on Saturday and Sunday. For this reason, we have instituted a Stage 1 flood alert that will run through the weekend. This is the lowest alert on our flood scale, and means there is the potential for nuisance street flooding.

Wednesday

Skies should be partly sunny today, and this will allow temperatures to warm into the mid- or upper-80s later on. In terms of rain, we expect a cluster of storms to approach the region from the west this afternoon. The question is how long they hold together, and whether they migrate all the way to the coast where a capping inversion should be a bit stronger. Therefore areas west of Interstate 45 and north of I-10 have the best chance for rain this evening through about midnight, and there could be some briefly heavy showers dropping an inch or two of rain over parts of the area. Rain chances fall back late tonight.

HRRR model depiction for radar at 10 pm CT Wednesday. NOTE this is just single model forecast. (Weather Bell)

Thursday

This will be another day with the potential for showers and thunderstorms to develop, with briefly heavy rain across the metro area. About half of the area will probably see some rainfall. As skies will be mostly cloudy, temperatures should remain in the mid-80s on Thursday.

Friday, Saturday, and Sunday

As an upper-level low pressure system moves closer to our region this weekend, we’ll see increasingly favorable conditions for widespread rainfall beginning Friday. As usual, the details are difficult to pin down, but these kinds of atmospheric conditions typically produce heavy rains that can quickly back up streets. If you’re thinking about weekend plans, our best guess is that the period most likely to see showers and thunderstorms will run from mid-day Saturday through Sunday morning. But rain chances will be fairly high from Friday through Sunday, and most of the area will likely see accumulations of 3 to 6 inches. Otherwise, expect partly to mostly cloudy skies, with highs in the low 80s.

NOAA rain accumulation forecast for now through Monday night. (Weather Bell)

Next week

I’d love to tell you that by Monday we’ll see plenty of sunshine, but the reality is that we’ll probably see a continuation of healthy rain chances—in the 50 percent range—through the middle of next week. The overall pattern will then likely turn drier by the end of next week, with more sunshine and temperatures likely approaching the 90s. It is June, after all.

A wet week is on tap for Houston, and we’re issuing a Stage 1 flood alert

Good morning. It’s June 1, which for us marks the beginning of summer and the official start of the Atlantic hurricane season. The next four months are the hottest of the year—with temperatures peaking in August. However this year we’ve had a slower build into summer, with average temperatures about 1 degree cooler than normal in May. This was due, in large measure, to most of the area seeing rain most days during the second half of the month.

This cooler-but-wetter trend looks to continue into at least the first week of June. Overall, our forecast for the week ahead, including next weekend, look quite wet. The combination of a moist atmosphere, feeding off the Gulf of Mexico, and a series of slow-moving atmospheric disturbances will drive rain chances upward through the weekend, at least.

On average, much of the region will probably receive on the order of 4 to 6 inches of rainfall, with some areas receiving more. Over an entire week, this is manageable of course. What we’re more concerned about are areas receiving that much rain in a couple of hours, and causing flooding problems on roadways. Because of this potential for flooding, and our already sodden soils, we’re issuing a Stage 1 flood alert on our flood scale for the entire Houston region, and this is likely to remain in effect through at least Sunday.

Tuesday

The first opportunity for rain comes today, as a band of storms moves from west to east across the region. These storms produced very intense rains overnight in areas far west and north of the Houston metro area, but appear to be weakening as they approach our region and move through today. While most areas will get less, a few parts of Houston may see 1 to 3 inches of rain today. Highs will top out in the low- to mid-80s with the persistent cloud cover.

Wednesday

This will be another day of fairly widespread showers, with half or more of the region seeing at least some rainfall amidst clusters of showers and thunderstorms. Highs will again be moderated by clouds, topping out in the mid-80s. These two days will probably be something like appetizers for the main event later this week.

Thursday, Friday, Saturday and Sunday

The pattern will become even more favorable for heavy rainfall by around Thursday, when a slow-moving upper-level disturbance begins to directly impact our weather. With these slow moving systems we are concerned about the potential for training storms and flooding. While it’s difficult to say much about each of these individual days, there will be the potential for heavy rainfall each day, along with mostly cloudy skies. This will help to moderate temperatures of course, and we expect to remain in the low- to mid-80s through the weekend. If you have outdoor activities planned for the period ahead, please know that you should definitely have a backup plan.

NOAA forecast for rain totals from now through Monday. Some areas will see more. (Weather Bell)

Next week

When will Houston emerge from this wet mess? We don’t have a confident answer for you, but for now I think the pattern will begin to moderate about one week from today. Until that time you should keep an umbrella handy, keep an eye on the radar, and be weather aware. We’ll be here.