We’re issuing a Stage 1 flood alert for tonight and tomorrow across Houston, with the greatest risk north

In brief: Although considerable uncertainty remains, the potential definitely exists for heavy rainfall across the Houston metro area beginning this evening, and persisting through Thursday. The greatest risk for strong storms is north of Interstate 10, but heavy rain could still develop further south.

We’re continuing to watch for a potential flash flooding event in the Houston metro area later this evening, overnight, and Thursday. This will be driven by a fairly potent atmospheric disturbance that will drive one or more rounds of showers during the next 24 hours. The heaviest rain is likely to fall between midnight tonight and noon on Thursday, so definitely plan to check conditions before venturing out tomorrow morning.

Some of these storms could be severe, with the threat of damaging winds. But primarily, the main concern is heavy rainfall. This is particularly acute for areas north of Houston, some of which already received 5 to 10 inches of rainfall earlier this week. Soils are wet and rivers and creeks are already high. Major reservoirs are full. So these showers will not be particularly welcome.

Generally, I think areas north of Interstate 10 can expect 2 to 4 inches of rainfall through Thursday night, but what concerns me is the potential for higher bullseyes of 6 or more inches. These accumulations will depend upon the speed at which these lines of storms move through, and that’s just not clear right now. For areas south of Interstate 10 the risk is not zero, but it is lower. I’d expect between 0.5 and 2 inches of rain for locations closer to the coast.

This is a difficult forecast because we’re getting mixed signals. On one hand, there is the potential for a pretty heavy rainfall event, especially north of Houston. Yet there are some scenarios in which things don’t fully pan out. So we’re going with a Stage 1 flood alert to raise awareness about the potential for flooding tonight and on Thursday. Things could get worse than that up north, however.

We’ll be back with an update early on Thursday morning.