Good morning. Very heavy rains have fallen overnight along a nearly stationary boundary that is anchored across west Houston. As a result, as much as 5 to 7 inches of rainfall have come down near Katy and the Addicks and Barker reservoirs. A flash flood warning is in effect for these areas through 10 a.m. Thursday morning, and you can expect widespread street flooding.
Houston radar shortly before 6am CT. (Radar Scope)
Thursday
The heavy rainfall over the western part of the region should wane somewhat during the daytime hours. However, the overall pattern facing the region remains more or less the same. Very high atmospheric moisture levels coupled with an unstable atmosphere will continue to support heavy rainfall for the next day or two.
While we think there may be something of a break in storms today, another atmospheric disturbance should move into the area tonight, bringing another healthy chance of widespread showers and thunderstorms. It seems unlikely that any areas will see 7 inches more on Thursday night, but this pattern has already shown what it is capable of. Aside from rain chances today, mostly cloudy skies will limit highs in the mid-80s, with a light south wind.
Friday
By Friday the threat of heavy rainfall should be declining—although it is not going to go entirely away. The driver of this will be a slowly drying air mass that should help to set an upper limit on rainfall rates. Nevertheless, we still expect fairly widespread moderate showers and thunderstorms on Friday, with cloudy skies and highs in the mid-80s.
Today ended up being a mostly quiet one again for most of the region, with just a few showers here and there. Rainfall since about 7 AM today has been more than manageable with most areas seeing minor amounts. A couple areas, notably up toward Conroe and south toward Santa Fe and Galveston have seen close to or in excess of an inch of rain since 7 AM today.
Rain totals since 7 AM have been mostly minor, with a couple exceptions. (Harris County Flood Control)
So we’ve done alright so far. Heading into tonight, I will level with you: Eric and I are scratching our heads a bit. Yesterday, it appeared we had a pretty favorable setup for heavy rain leading into the nighttime, and yes it materialized, but not in the way we were anticipating until late in the game. Tonight we are presented with a set of data that is different than yesterday but does offer up some risk of heavier rainfall in spots.
Brace yourselves, some serious nerd-speak is coming in this paragraph: I just dug through a lot of the meteorology here, and what I’m coming up with does make me think some areas could see some locally heavy rainfall tonight. For one, we have a weak upper level low over Southeast Texas. Those are notoriously fickle systems, and they can become more active at night. Second, it appears there is some sort of weak boundary at the surface that’s roughly along US-59/I-69 from Victoria through Houston that then arcs to the east toward Beaumont. Boundaries like this can act as focusing points for thunderstorms. Third, model parameters suggest a good bit of instability in the atmosphere tonight. Higher instability means thunderstorms can develop and sustain themselves. Fourth, models suggest plenty of atmospheric moisture is available right now. Observations back this up, as the weather balloon launched at 7 PM from Lake Charles shows precipitable water values in the 90th percentile for this time of year, which means if storms can get going, they can rain heavily. Lastly, it appears that winds about 5,000 feet above the surface are going to increase off the Gulf from south to north tonight, aimed east of Houston. Winds at that level can act to provide additional ingredients and moisture needed for heavy rainfall.
This is a long winded way of saying that the meteorology that’s showing up right now backs up the idea that we could see some heavy rainfall tonight.
The question, as always, is can the ingredients actually come together in such a way to allow this to transpire. I really don’t know. These are fickle, tricky situations, so there’s always a chance a few things don’t happen and you end up with a couple isolated showers and storms and that’s that. But, if things do come together, we could be talking about repetitive showers and storms for some areas.
So, for most of the area tonight, let’s just call it a few showers or a storm possible. Some folks will see nothing. Others some heavy rain for a time. Totals of a quarter inch to an inch.
NOAA’s rainfall forecast through Thursday morning at 7 AM shows better odds of heavier rains east of Houston. Most places will just see some sporadic showers, but a few may see some more sustained, heavier rainfall. (Weather Bell)
Put a pin over downtown Houston and if you go south of there and east of there, you stand the chance of seeing perhaps some more sustained rainfall. In those places, I would say your odds of seeing a quarter inch to inch of rain are higher than northwest of Houston. There may also be a few isolated locations that see as much as 2 to 4 inches of rain or a bit more in a worst case scenario. The odds of that happening are not high, but as I laid out above, the ingredients are certainly in place. If I had to focus on an area tonight for the highest risk of this it would be from Baytown to Beaumont.
Anyway, we just wanted to provide some situational awareness for you this evening. Be safe!
Good morning. Houston’s wet pattern will continue through the work week, although the most organized heavy rainfall should wind down over the course of this morning after a storm system pushes through the area. Please take care if you have cause to be out and about this morning before conditions should improve later today.
Wednesday
Moisture continues to move in from the Gulf, combining with an upper-level storm system to bring heavy rains to the metro area on Wednesday morning. The heaviest rains are generally to the south of the city now, and this mess should slowly begin to slide generally eastward, exiting the area entirely by 9 a.m. or 10 a.m. In the meantime, these storms should put a manageable 1 to 3 inches of rain down for most of the metro area—with the heaviest rains coming and lingering near the coast.
Storms are rotating around an upper-level low on Wednesday morning. (KKTV)
Although this will end our Stage 1 flood event, the rain won’t be over. Even as the storm system rotates away from Houston, additional moisture will be pulled inland and more showers will likely develop this afternoon. We’re not sure about this, because the atmosphere should be somewhat stabilized after this morning. In any case, storms this afternoon should be less organized. Highs today will likely only reach the mid-80s with cloud cover and rain.
Thursday
Healthy rain chances continue on Thursday, with a higher likelihood of moderate-to-heavy rain along the coast where moisture levels should be highest. Accumulations should be less than on Wednesday, however. Temperatures should remain in the upper 80s for most with cloudy skies.
Good afternoon. We’re continuing to monitor the threat of heavy rainfall during the overnight hours as a front sags into the Houston area, and stalls. And at this point, we believe this threat warrants a Stage 1 alert on the Space City Weather Flood Scale. However, we’re following the situation closely, and it may require an upgrade to Stage 2 this evening.
In anticipation of this threat, the National Weather Service has issued a flash flood watch for the entire metro Houston area, in effect from 7 p.m. tonight through 7 a.m. Wednesday morning. In terms of overall accumulations, they are forecasting widespread totals of two to four inches of rain through tomorrow morning, with isolated areas of six to eight inches possible. This is reasonable. However, these kinds of potentially heavy rainfall events, with a slow-moving system and very high levels of atmospheric moisture, are notoriously hard to predict.
At this time we do not have much confidence in where the rains will be heaviest—it could be anywhere from south of the city to the northeast. The good news is that we expect the storms to begin to clear the area by around sunrise, or shortly thereafter. By then the atmosphere will probably be pretty worked over, and we think storm coverage should be less during the daytime on Wednesday.
