For about a week now, when looking at the weather for Sunday, Jan. 20, we’ve discussed the timing and strength of a front expected to come through Houston just before or during the Houston Marathon weekend. There is now fairly high confidence the front will make it through on Saturday, and the front appears to be strong. The key questions we have now are rainfall/snow (unlikely, but impossible to rule out) and winds (a potential concern).
Assuming the front pushes through the region on Saturday, the most likely scenario is a clearing out of skies sometime Saturday night or Sunday. Under such a scenario, the region would see ideal cooling for Sunday morning. Right now, there is about a 90 percent chance the temperature on Sunday morning will fall below 40 degrees, and at least a 50 percent chance it falls to 35 degrees or below. Sub-freezing temperatures are certainly possible.
With no precipitation the most likely outcome on Sunday morning, the biggest concern I have is winds. These will of course depend on the timing of the frontal passage (an earlier front would give them time to die down), and other factors including pressure gradient. I think it is possible that we see anything from 5mph northerly winds up to 25mph (with higher gusts). It is impossible to forecast winds this far out, but I think there is a reasonable chance we see sustained winds in the 15-20 mph range in the wake of the front, which would produce wind chills down to around 20 degrees at the start of the race. Brrrr.
Bear in mind we are still a week away from the race, and there is always uncertainty in seven-day forecasts. But confidence right now is pretty high in a cold race day, with a potentially quite cold day given the possibility of winds.