Flash flood watch issued for Houston as storms approach

As we’ve been saying Houston has to get through one more bout of potentially heavy rain before seeing a reprieve from this wet pattern—and that bout is coming. In anticipation of that the National Weather Service has placed the entire region under a flash flood watch from 10am CT today through midnight.

Although conditions are dry at the surface, just above the surface moisture is starting to stream in from the Gulf of Mexico, and we’re going to see very high levels of atmospheric moisture today. At the same time a large upper-level system is moving in from the west, bringing with it the capability to lift this moisture upward. This lift will help to generate moderate, and then heavy rain later this morning and during the afternoon hours.

In its flash flood watch the National Weather Service is calling for 1 to 3 inches of rain for widespread areas, with up to 5 inches in isolated areas. This seems like a pretty reasonable forecast. Most areas should be able to accommodate these kinds of rains, but where the most intense rains come, in a short period of time, we will definitely see some street flooding at least, and the evening commute could be a bit of a mess. We’ll also have to watch for the potential of more widespread flooding if the storms slow as the move through. The heaviest rains should ease off this evening, although a chance of at least scattered rain is going to persist through the morning hours on Friday.

Aside from flooding, there is a slight threat of severe weather, probably primarily in the form of hail. I’d expect conditions for hail to be most favorable along the coast, where the boundary between warm and cool air is likely to exist.

After the rains end we should see clearing conditions on Friday afternoon, with mostly sunny weather on Saturday and Sunday. Highs will be in the mid- to upper-80s with lows down to around 70. Slight rain chances return late Sunday or Monday.