Before jumping into the forecast for the week ahead, I want to look back at the heavy rains the region received—or in some cases did not receive—to illustrate the perils of Gulf coast precipitation prediction. As you may recall, we predicted widespread variations in rain totals, but said some areas faced a Stage 2 flood alert on our scale. This essentially means we thought parts of Houston would see flash flooding, with mostly localized effects. With that in mind, here are the three-day rainfall totals from the storms:

The first thing I notice on the rainfall map is an extremely tight rainfall gradient. Essentially, if you lived southeast or east of Houston outside the Sam Houston Tollway you saw 2 inches of rain, or less. You might have wondered what the fuss was about with our flood scale. By contrast, a mere 50 miles away, a large swath from Lake Jackson to Sugar Land saw 6 to 12 inches of rainfall. This would have caused significant flooding problems had it set up just a little bit to the northeast, over the metro Houston area. Anyway, in the end, our forecast was pretty good. But if you lived in Galveston, you probably thought we oversold the event. And if you live in Needville, perhaps we undersold it. This is why flood forecasting is extremely difficult across such a large area.

Overall, despite the dreary Saturday that cost many of you weekend plans, this was a beneficial event. We had a dry spring across the region and are about the enter a period of time when 90-degree days are common, and soils dry out more quickly. Before this weekend’s rain, some southern parts of our region were already in an extreme drought (see map below), with large swaths north and south of Harris County in a severe drought. These rains will take a bite out of that drought.

Ok, now that the rains have passed, and we’ve talked a bit about them, let’s jump into the forecast for the week ahead. All in all, it’s pretty nice for the first week of May.

Monday

Today will be a warm one, especially if this morning’s widespread clouds break and skies clear a bit this afternoon. High temperatures have yet to officially reach 90 degrees this year, but could do so this afternoon at Bush Intercontinental Airport as warm air moves in from the Gulf of Mexico. Southerly winds will gust up to 20 mph. Monday night will be warm again, with lows in the 70s and high dewpoints.

Tuesday

A modest front will arrive on Tuesday to bring some relief. It looks like a broken line of showers and thunderstorms will accompany the front’s passage, but rain accumulations overall look fairly slight. The front should reach the central part of the region by around noon, and push off the coast during the afternoon. Winds will turn northerly in the wake of the front, with lows dropping into the 60s Tuesday night.

Wednesday, Thursday, and Friday

It’s May, so our weather is not going to become cold after this front passes. But we should see a nice influx of dry air to make for a pleasant end of the week. These three days will likely be mostly sunny, with highs in the low 80s, and lows in the low- to mid-60s, generally. Enjoy the dry air, as there won’t be all that much of it left before summer arrives.

Saturday and Sunday

A returning southerly flow should make for a warmer weekend, with skies turning partly to perhaps mostly cloudy. Highs will likely return to the mid- to upper-80s with some slight rain chances. This should set the stage for even warmer conditions next week.

Good morning. As our wet pattern continues we’re in for another rainy 24 hours across the Houston region. But these moderate to heavy showers should fall mostly on the beneficial side of impacts, helping to blunt our emerging drought, rather than provoking significant flooding. Therefore we are lowering our Flood Scale alert to Stage 1.

The primary area of concern today and tonight will be areas southwest and south of Houston, closer to the upper-level low that has been responsible for this wet pattern. Areas south of Interstate 10 could see an additional 1 to 3 inches of rain today, with isolated higher totals, while areas north of there should see less. Some parts of the region may see a break in the showers later this afternoon before a final slug of rainfall this evening and overnight. Rain showers should end by sunrise on Sunday, or shortly thereafter.

Our region’s bayous and waterways should be able to handle these kinds of rains, but under slow-moving storms we may still see some streets briefly flood. Bear that in mind if you venture out far from home today. If you’re holding out hope for outdoor activity this weekend, Sunday should be a good bet. I expect skies will turn at least partly sunny during the afternoon hours, with highs in the mid-80s.

If this forecast changes, we’ll update accordingly.

Today has worked out rather well so far for most of the area. South and east of Houston was minimally impacted as expected, with under an inch in most locales. North and west of Houston saw roughly 1 to 3 inches on average. The jackpot occurred in Waller County, as Eric discussed this morning. Threemile Creek at FM 362 just northeast of Prairie View was today’s champion with nearly 6.5 inches of rain.

While that’s certainly a lot of rain, thankfully flooding has so far been restricted to some sporadic street flooding and some lowland flooding in rural Waller County. If you do need to travel between Magnolia and Prairie View tonight, use caution.

So as of 8:30 PM the radar is quiet in our area. There are two clusters of rain right now: One is just moving east of I-35, east of Austin and San Antonio. The other is sitting offshore between Corpus Christi Bay and Matagorda Bay. Everything looks fairly innocuous now, but after midnight tonight, storms are likely going to explode to our southwest. Significant, widespread heavy rain is likely, well to the southwest of Houston. The area between Corpus Christi and Victoria seems to be the most likely to see significant 4 to 8 inch totals, well away from the Houston area. The HRRR model depiction of what radar could look like overnight is shown below.

Folks in Wharton or Matagorda Counties will want to pay attention to things overnight I think, but even they may be a bit far enough northeast to avoid the real heavy stuff. This area of rain is likely going to creep closer to the Houston area on Saturday morning. Thankfully, it should also begin weakening around the same time, so while I would plan on some rain for your Saturday morning activities, if everything goes according to forecast, we should see minimal issues on area roadways.

As always with upper lows, there is a tinge of uncertainty underlying everything. However, there is very good model agreement on the general theme of things tonight and tomorrow, so we aren’t especially worried. With that said, we will maintain a Stage 2 flood alert. But honestly, that’s mainly for areas that have already been hard hit, like Waller County, although the rains don’t look too serious there tonight and the first half of Saturday.

Also, folks near Galveston Bay have been removed from the NWS Flash Flood Watch as of late this afternoon. Depending on how things go tonight and early tomorrow, Eric and I will consider pulling back to a Stage 1 alert on Saturday. Fingers crossed.

Saturday afternoon and evening

As of this evening we think most Saturday afternoon plans should be fine. There may be a few showers or some light rain around, so have an umbrella handy. But you might be able to swing most plans without issue. Saturday evening may see conditions go downhill with a line of thunderstorms coming out of Central Texas and sweeping across Houston after 9-11 PM or so. Conditions would improve greatly on Sunday. We’ll update you on that tomorrow morning.

Here’s a quick breakdown of how Saturday looks:

6 AM-Noon: Heavy rain possible, especially west of I-45 and south of I-10. Scattered showers and storms possible elsewhere.

Noon-6 PM: Scattered showers or some light rain, but intensity and coverage of rainfall is expected to diminish.

6 PM-Midnight: Increasing chances of rain and thunderstorms as you get closer to midnight.

We will freshen things up for you again tomorrow morning. Have a good night!

The most intense storms that developed early Friday morning have been winding down as we approach the middle of the day, and this general weakening trend should continue through the afternoon.

For most of us, the rains have been more than manageable so far, with 1 to 2 inches across much of the region. But areas north and northwest of central Houston, including northern Waller County and western Montgomery County, have received 4 to 6 inches. While bayous remain mostly within their banks, these rains have saturated soils in the region.

Given the unpredictability of this kind of weather system, we still have lots of questions about the forecast. As a best guess, the next area to watch later today will be the Matagorda Bay region, and the potential for storms that develop there to migrate into the Houston area overnight and on Saturday.

Matt did an excellent job of summarizing things in this morning’s post, but the bottom line is that we still expect a situation where some area roadways may see high water during heavy rains. However, we’re not concerned about flooding of homes and businesses at this time, and think bayous are well positioned to handle these rains. For this reason we remain solidly in a Stage 2 flood alert, and don’t anticipate the need to increase this.

There may be some let up in storms on Saturday afternoon or evening, before a final round of storms pulses through the area on Saturday night and Sunday morning. Again, we think this will be mostly manageable for the area’s floodways, but you should be aware of the potential for moderate travel disruptions through Sunday morning.

We will post our update no later than 9 pm CT on Friday evening.