Oh, my fellow runners, if you want to be depressed then take a look at the GFS ensembles that came out this afternoon. I’ve annotated the forecast, which takes into accout about 50 different runs of the GFS model based upon observed conditions this morning.
What’s depressing is that the range of lows forecast by the GFS model for Sunday morning, January 15th, runs from about 63 to 73 degrees, and the corresponding dewpoints are nearly as high, meaning we’d be looking at a humid race day too. This is about the worst-case scenario, barring fire-and-brimstone-type thunderstorms with tornadoes thrown in.
(Space City Weather is sponsored by Westbury Christian School for this month)
Fortunately the GFS is just one model, and the European model offers a slightly more hopeful forecast. Looking at its ensembles this afternoon, the models show a range of likely low temperatures from the low 50s to the low 70s. However there are some scenarios in which the European model actually drags a cold front through the region before the race day, which would bring even colder weather than that. The only reason I give this model solution some credence is that the global models have been hanging on to high pressure ridges for a little too long this winter.
As for precipitation, there’s not much we can say right now. But if next week is going to be warm (and it is) that means atmospheric moisture levels will be rising. If there are some atmospheric disturbances that arrive by the 15th, then there would be plenty of moisture to work with.
Bottom line: The greatest likelihood (50 percent) for Marathon Day in Houston is still well-above normal temperatures (think lows that morning of 65 degrees or greater). I’d say there’s about a 35 percent chance of lows between 55 and 65 degrees. And for a wild card, I’ll throw in a 15 percent chance that we get really lucky, and a front moves through, bringing use a much colder race day. Once again, our only real saving grace here is that the marathon is still nearly 10 days away, so there’s a fair amount of uncertainty in the forecast. But I have to say the signal for warm weather remains quite strong.