We’ll say goodbye to sunshine for a couple of days, and our focus will now turn to the potential for severe weather on Friday night. A strong line of storms will sweep through Houston from west to east, likely from about 9pm to 3am. All of the usual threats will be there—large hail, damaging winds, and potentially tornadoes. Because of the storm’s progressive movement, we do not expect rain totals much above 0.5 to 1.5 for widespread areas, with higher isolated amounts. It may be severe, but it will be over quickly.
Today will be mostly cloudy, with southerly winds continuing to pile moisture into the region. However, a fairly stiff capping inversion—this is situation where warmer temperatures higher up in the atmosphere prevent warm, moist air at the surface from rising—should preclude all but some scattered, light showers today. Highs will reach the upper 70s for most of the area, and temperatures Thursday night will not fall much below 70.
Friday will start out a lot like Thursday, with an increasing chance of storms throughout the afternoon and evening hours. While you may see some showers during the daytime hours (which will be warm, with highs again likely in the upper 70s), the main event will be a line of storms moving through. NOAA’s Storm Prediction Center has expanded the area of “enhanced” weather somewhat southward and westward. This means it will be possible, but by no means certain that we will see strong wind gusts of 75+ mph, large hail and tornadoes. There will be heavy rainfall too, but it should move through quickly. The bottom line is that if you are out and about on Friday night, be very weather aware. (I’d definitely plan to be home before the storms hit). And if you’re at home, be prepared if a tornado warning is issued for your area.
As quickly as it boils up, Friday night’s severe weather will exit the region before sunrise on Saturday. This will lead to clearing skies and pleasant weather, with high temperatures near 60 degrees. Lows Saturday night will be chilly, perhaps around 40 in Houston, and in the 30s in outlying areas.
The second half of the weekend will also bring ample sunshine, and highs in the low 60s. However, a returning flow of moisture from the Gulf will return to warm us up by Sunday night and Monday.
This return flow from the Gulf of Mexico will set the stage for warm and potentially wet weather through the middle of the week. We have no expectations for storms, but rain chances will be on the order of 40 percent or so each day beginning Monday, with cloudy skies. Daytime highs will push into the 70s, with warm nights in the 60s likely.
So what does this mean for the end of next week? We are now 10 days out from the Houston Marathon so we can begin to have some slight confidence in the forecast. Alas there is not too much clarity beyond the warm midweek. The GFS model and its ensembles lean toward a Thursday-ish cold front, while the European ensembles are generally more delayed, leaving it to Friday or Saturday. The former solution, the GFS, would mean that Houston is beginning to warm up by Saturday, with a morning low in the 50s or low 60s. The European solution suggests potentially cooler weather, with lows in the 40s. Right now, if I had to guess, I’d pinpoint the race time temperature at 50 degrees. But I would not feel great about that forecast—at all.