Sunday’s heavy rains signal a pattern change for Houston

After a prolonged dry spell, rains returned to Houston on Sunday. For some areas such as northwest Houston, rain totals runneth over with 4 to 6 inches. For other areas, including parts of southeast Houston, just a few drops fell. Probably the bigger news is that we’re now likely transitioning toward a wetter period after an extremely dry month. We’re also going to need to watch for a potentially rainy Memorial Day weekend.

Sunday’s rain accumulation. (National Weather Service)

Monday

Like on Sunday, atmospheric moisture levels remain pretty high, and enough instability remains that we’re likely to see widespread showers again later this morning as temperatures rise into the 80s. I don’t think accumulations will be as high as on Sunday, but we’ll definitely need to watch out for a few heavy showers. Temperatures probably will remain in the upper 80s with lots of clouds. I’d expect any remaining showers to die off this evening with the loss of daytime heating.

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Storms rolling through northern half of Houston

Rising moisture levels have combined with rising air to form some moderate-to-strong showers and thunderstorms this afternoon, primarily to the north and west of Houston. The National Weather Service has issued a flood advisory for some of these areas where up to 5 inches of rain have fallen. The advisory (shown below) is in effect through this evening for Houston.

Area of flood advisory in effect until 8:15 pm Sunday. (National Weather Service)

These storms are associated with an outflow boundary, and this complex should slowly move to the southeast this evening. As it does so, rain showers should move into the central and perhaps southern Houston areas, but the storms should also weaken as this happens because atmospheric conditions are less favorable closer to the coast. This is somewhat unfortunate, because the southern half of Houston has not seen significant rainfall in a month. Overall, I would expect showers to die out late this evening, or by around midnight.

Some street flooding is already occurring in areas of the flood advisory, but because the region has been so dry for so long, bayous and creeks should remain within their banks.

Some Houston locations have not seen rain for nearly a month

So far this month, Houston’s Hobby Airport has recorded only a “trace” of rainfall, which means there has been no measurable amount of precipitation. Looking back at the records for Hobby Airport, which date back to 1931, this has happened just twice at the site previously—in 2003 and 1937. Although I think there’s a chance the airport site makes it through this month without getting any measurable rainfall, I think there’s a greater chance that the region finally sees at least some modest rainfall next week. Let’s hope so, because Hobby (and a lot of other locations in the southern half of the metro area haven’t seen meaningful rain since April 21).

Houston’s Hobby Airport hasn’t recorded measurable rain since April 21. (NWS/Space City Weather)

Thursday and Friday

Houston will remain unseasonably warm to end the work week, with high temperatures likely in the low- to mid-90s, and mostly sunny skies. Nighttime lows in the lower 70s. Near zero percent chance of rain.

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Our official outlook for Summer, 2018 in Houston

Long-time readers of this site will know that we don’t place a whole lot of confidence in seasonal forecasting. Trying to predict weather (note that’s “weather” not “climate”) conditions months in advance is not exactly an exact science. Case-in-point: Much of the Houston area has not gotten a drop of rain in the month of May, and the next week or so looks dry. And yet here’s NOAA’s monthly outlook for precipitation for the month of May, issued on April 30th:

Probably of wetter (green) or drier than normal conditions in May. (NOAA)

This forecast, quite clearly, will likely bust. And it was issued the day before the month of May began. So while I do think there is some value in seasonal forecasting, you should not take it to the bank.

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