As promised, I’ll be providing daily weather outlooks for the Chevron Houston Marathon from now until race day, Jan. 17th.
At 13 days out there’s still not a whole lot we can say with confidence, especially because forecast accuracy after 7 to 10 days is pretty low even though forecast models run out to 16 days. With that said I’m feeling decent about not seeing abnormally warm conditions on race day, and we may very well see cooler than normal conditions. So let’s discuss what we know, and what we don’t.
Perhaps the best way to gauge conditions from this far out is to look at the ensemble runs of global forecast models. That is, the GFS and European models are each run about 50 different times with slightly different starting conditions. This gives a range of outcomes, and from looking at all of these ensemble runs we can get some probabilities on conditions. For example, do most of the ensemble runs show warmer or colder conditions?
The GFS model is colder than the European during the next two weeks as it predicts a major Arctic outbreak across Texas in about 11 days time. If this event occurs we could see very cold temperatures on marathon day, like in the low 30s on the morning of the run. (Is that too cold for most people?)
Anyway, the model forecasts the probability of a high temperature greater than 50 degrees Fahrenheit at noon to be 30 percent, or less. This is good, obviously, because anything warmer than 50 degrees can become uncomfortable after several hours of running.
As long-time readers will know, the European model tends to do a little better than the GFS when it comes to forecasting. Unlike the GFS model, it does not show the very strong outbreak of Arctic air in about 10 days (it is quite a bit warmer). This is a little bit concerning, but the European does show a cooling trend by the weekend of the marathon.
I reviewed the 50 ensemble members of the European model run for temperatures at 6 a.m. on the morning of the marathon. Of those, 36 show colder than normal temperatures, 2 show neutral conditions, and 12 are warmer than normal. That’s a 75 percent chance of colder-than-normal conditions, if the European model is to be believed.
Here, then, is my latest forecast for conditions on the starting line of the 2016 Houston Marathon.
Temperature
Race-time temperatures will be normal (low 40s), or below normal.
Confidence: Medium
Precipitation
There is a decent chance of light precipitation, depending on the location of low pressure systems.
Confidence: Very Low
Winds
It is difficult to make any predictions about winds at 13 days out.
Confidence: Very low
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Thanks! Been waiting for this – I’ll be following you daily and sharing with my running groups.
Thanks Cindy. I’m far from certain about the forecast, but it’s certainly trending in the right direction.
Temps in the 30s would certainly be chilly for spectators that are standing/sitting still. By itself, it’s still quite bearable by runners. (Don’t be surprised if you even see a handful of shirtless out there!) I will be watching for wind and/or precipitation to gauge my own “cold race misery index.” Stinging winter rain blowing on my face from the north is not my idea of fun!
Thanks, Vince. I haven’t tried to run long distances in the 30s before.
Unless you don’t like cold conditions, one avenue is to dress for the end of the race temperature and conditions, because you will warm up.
Sky conditions would be nice to know, too, as 50 degrees in sun like today feels different (warms you up quicker and longer) than 50 degrees with overcast skies. My preference is overcast, so my energy doesn’t get sapped as quick.
Thanks for the updates and explanations.
The wait time in your corral can be chilly. Folks wear things they can throw to the side once the race starts. Always humorous to see the barricades draped with various garments and tube socks (aka cheap arm warmers). The items are picked up and given to shelters – so it’s a win-win.
By the way, in the event that there is wind and frigid preciptiation, a lawn-and-leaf size garbage bag to wear can be your best friend while waiting in a chilly corral. Rip a hole in the bag bottom to stick your head out of. Once you can get going, you should warm up and be able to ditch it. And yes, I’d say it’s very important to be prepared for end-of-race conditions. Those closing miles on Allen Parkway lack shade and could be surprisingly toasty by late morning if it’s sunny.
Thanks, Vince, that’s great advice!
I am definitely worried about the heat during the last hour or so!
Nice! Thanks for sharing your insights. Low 30s is a little colder than my personal optimal, but is close enough to perfect. I cover my hands, my ears and the top of my head, and wear a long sleeve tech shirt.