Storms have exploded northwest of Houston today with numerous reports of large hail, up to as big as golf ball size or larger. As I write, this large hail is possible near Bryan in the Brazos Valley.
Radar shows strong and severe storms in the Brazos Valley racing southeast toward the Houston area this afternoon. (College of DuPage)
As a result of this, a Severe Thunderstorm Watch has been hoisted for the entire Houston area through 9 PM this evening. The main threat will be between now and 6 PM I think, however. These storms near Bryan-College Station are hauling south and east around 20 to 30 mph, and new storms are trying to blossom out ahead of them.
2:20 PM – Severe-thunderstorm warned storm moving into the BCS area capable of producing golf-ball sized hail, frequent lightning and heavy rainfall.
The main threat from today’s storms is likely to be large hail. Not everyone will see hail, but those that do (most likely along and north of I-10) could see hail to the size of golf balls or even a little larger. The hail threat today is legitimate. A secondary threat will be strong winds, capable of knocking down trees or power lines in spots. A very small tornado threat is there, but it’s not especially high at this time. We’re focused on hail and wind today I think. Heavy rain is also possible from any of these storms.
While the severe threat should fizzle after sunset, we may see additional rounds of showers or even some thunderstorms into later this evening. We’ll update again if things look more significant. But please stay weather aware through this afternoon and evening.
Good evening. Today started out as a spotty day, before thunderstorms really revved up over the northern and western halves of the metro area, including some hail in The Woodlands and eventually a tornado warning for northwest Harris, Waller, and parts of southern Montgomery Counties. As I write this, those storms have reorganized and are making one final push south and east across the area. Carpenter’s Bayou at I-10 near Channelview has received over 1.5 inches of rain in the last 15 minutes. Scattered heavy rains will slowly slide south and east and dissipate over the next few hours.
Rain totals today have been widely, widely variable.
Rain totals have ranged from less than 0.10″ in the Med Center to as much as 4 inches near Crosby. (Harris County Flood Control)
The map above is intentionally skewed to show the north side of the metro area, as there’s been far less rain to the south today. Rain totals on the east side will increase markedly in spots before the night’s up, as this map is only through 7:45 or so. You can view more rain totals and more time scales at Harris County’s outstanding rainfall page. Rain totals were paltry to non-existent southeast of Houston and toward most of Fort Bend County.
Overnight
Looking at radar across Texas this evening, it’s pretty evident that we are not done tonight.
A radar loop over Texas shows additional storms organizing in Hill Country and South Texas. Those will sweep through Houston overnight. (College of DuPage)
Storms are pooling west of I-35 this evening, which is something that had been well telegraphed on weather models the last couple days. Those will move through the area overnight.
So expect conditions to improve between now and midnight, though rain may continue at times. Weather models have been suggesting the next round of storms would arrive in Houston around 3 AM or so. I would not be shocked if that occurs a little sooner based on radar. When that happens, we’ll probably have some loud, wake your dogs up thunder, heavy rain, and potentially some strong gusty winds. The good news is that storms should be moving, so although some brief street flooding may occur, things should not last too terribly long. New rainfall should range from a half-inch to perhaps 2 inches over most of the area.
Memorial Day
Storms will exit after the morning, and we’ll probably be left with clouds and a few showers. The atmosphere will likely need time to recover, so the majority of Monday morning and early afternoon we think will be fine right now. In the late afternoon and evening, we may see conditions become more conducive for storms to redevelop. Exactly where and when? TBD. But those would probably be similar in nature to what we see occurring this evening: Slow movers, occasionally strong, and capable of putting down 2 inches in an hour, meaning a few unlucky spots may receive another few inches of rainfall with those. So yes, street flooding will again be possible under any storms.
Temperatures will be held down in the low- to maybe mid-80s.
Beyond Monday afternoon
With a low pressure system in the upper atmosphere placed just to our north and west for Monday night, Tuesday, and Wednesday, you can expect additional rounds of thunderstorms across the area, with varying degrees of intensity each time. We will likely need to watch for areas of flooding risk over more of the area through that period, details TBD. By Thursday, that upper low should begin to migrate toward Louisiana. That should mean improving weather heading into next weekend, but I don’t want to get your hopes too high just yet. We’ll keep you posted.
An active weather pattern over Texas will slowly increase our shower chances each day this weekend. Generally, the deeper into the holiday weekend you go, the better the rain chances will become. Today and tomorrow probably won’t be too bad. Sunday could see heavier rain west of Houston and Monday could see more widespread coverage of thunderstorms in the Houston area. Specifics beyond “showers and storms are possible” will be hard to come by more than 12 to 18 hours in advance; such is the nature of weather patterns like this. Let’s walk through each day and tell you what we know at this time.
Today
Expect some clouds and some sun today, with sun probably becoming more dominant as we roll toward afternoon. There’s a little more moisture available today, so we will at least mention that a shower or storm is possible. As I am finishing writing this, it’s evident that some showers have popped up out toward Wharton County and up through Columbus, well west of Houston but somewhat sudden and unexpected this morning. We think most activity should be spotty (call it like 10 to 20 percent or so), and storms should be very much the exception, not the rule today but hopefully these morning showers are not a harbinger of a busted forecast to come. We will see!
It’ll be hot and humid with highs around 90° or so for the fifth day in a row.
Tonight
Another round of showers and storms in North Texas may just have enough “oomph” to hold together as it drops south and east late tonight. We could see a shower or a thunderstorm, mainly north of Houston after 3 AM or so. For most of us? Just mostly cloudy with a slight shower chance or some mist. Lows will be in the 70s.
Saturday
On Saturday, the best ingredients for thunderstorms remain mostly inland or to our west, which means Hill Country may be the favored area for more numerous showers. We’ll call it a spotty day once again for Houston with a few showers or storms possible, once more being the exception rather than the rule. Odds of storms may go up a bit as you go to the north and west of Houston.
Rainfall between Saturday morning and Sunday morning is likely going to be most significant west of I-35, or way back in Hill Country or parts of South Texas. For Houston? Probably not too significant. (NOAA via Weather Bell)
Look for another hot day with highs likely staying in the upper-80s or low-90s under partly to mostly cloudy skies.
Sunday
So on Sunday, the best ingredients for storms drift a little closer to Houston. While we think the coverage of storms will still be highest to the west of Houston, there should be slightly better odds for much of the area to see storms. I would say storm chances jump up close to 50 percent on average for Sunday afternoon, higher west of I-45, lower east of I-45.
Storm chances on Sunday will still be highest north & west of Houston, but most of the area will be at least at risk for some storms Sunday afternoon. (NOAA via Weather Bell)
Sunday’s storms could also be better organized than what we see Saturday in Texas, so heavier rain is possible. We would say that areas west of Grand Parkway up through Conroe stand the best chance of heavier rains impinging on plans Sunday afternoon. But again, specific details are tough to pin down, so most of the area has at least a chance at some storms Sunday.
A muggy Sunday morning in the 70s will give way to highs only in the mid-80s, maybe upper-80s with clouds.
Storms this afternoon were expected to dump heavy rain in a few small areas around the region. What we are seeing is something more robust than that, as widespread heavy rain and some areas of street flooding are ongoing. Flood Advisories are posted for the entire Houston area, and the Pasadena area is now under a Flash Flood Warning through 5:15 PM.
Areas south and east of Houston, including Pasadena have been hardest hit by heavy rain, and a flash flood warning is posted until 5:15 PM there. (NOAA)
Radar as of 3:15 PM shows a cluster of heavy rain that has migrated west over most of the Houston area.
Radar shows widespread heavy storms in the Houston metro area, with the heaviest rain south and east of the city and also migrating westward. (RadarScope)
This is basically going to need to rain itself out now over the next 3 to 4 hours. Pasadena has been fairly hard hit with nearly 4 inches of rain so far.
Rain totals of nearly 4 inches have occurred so far today near Pasadena. It is still pouring there. (Harris County Flood Control)
For the sake of simplicity I’ve just shown part of the metro area above. You can always check rain totals over various times over the larger area at the fantastic Harris County Flood Control gage site. Some folks will see little to no rain (especially northeast of IAH Airport and perhaps well south toward Lake Jackson and Freeport). Others may tally 5 to 6 inches or more when all is said and done this afternoon.
So heavy rain, storms, and street flooding are likely in many spots through 7 PM. Storms will fade after that. We enter a quiet period later this evening and into the early overnight.
Round 2 of storms will arrive here later in the overnight. The timing of the next wave of storms has sped up since this morning, and it now appears we will see heavy rain and storms resume after 2-3 AM (about 2 to 3 hours faster than expected this morning). Below is what one model thinks radar will look like at 3 AM Saturday.
The HRRR model suggests a large cluster of heavy thunderstorms will plow through the region between 2 and 5 AM Saturday. (Weather Bell)
Other models vary a bit on timing and orientation, but all show the entirety of the region seeing a period of heavy rainfall. Another 1 to 3 inches of rain will be possible with this. This would likely lead to widespread street flooding, especially around the hardest hit areas so far with today’s rains, where the ground will be very saturated.
As for Saturday afternoon? There is a chance we see another round of rain and storms, but we still do not have much confidence in details yet to determine whether we need to be concerned or not. We will update you either tonight or early Saturday morning. A reminder that we went with a Stage 1 on our Flood Scale this morning. See our earlier post for more details on that. Stay safe, and remember to never drive through flooded roadways.
