If only the Houston Marathon were run this morning. Yes, it’s cold on the morning a week from the marathon, but temperatures are now above freezing, winds are light, and skies are clear. Unfortunately, as we look ahead to next weekend, the forecast is anything but clear.

Here’s what we know as of Sunday morning about the week ahead: Temperatures this week will be warm. Highs from Tuesday through Saturday will be warm, likely between 70 and 80 degrees for nearly all the metro area. We also know that at some point toward the end of the week a cold front will move into Houston—but the timing is uncertain, and therefore so is the forecast. In addition to concerns about temperatures we’ve also got to worry about precipitation along with the front, especially if the cold front passage occurs between midnight Saturday and noon on Sunday, which seems entirely plausible at this point.

In terms of uncertainty, here’s what I mean. About 28 of the 50 ensemble members of the European model bring the cold front though Houston by 6 am CT on Sunday. But only half of those models bring the front through substantially before the start of the marathon, such that any associated precipitation is likely to have cleared out.

And so it is very difficult to make a forecast for the marathon. There is perhaps a one-third chance that the front moves through on Saturday, making for a clearing and colder race morning. There is perhaps a one-third chance the front arrive just before, or during the race, which makes for a wet race morning, with perhaps 1 inch of rain or so (potentially a wet and windy mess). And there is perhaps a one-third chance the front doesn’t make it through until after the race, making for a warm, humid run.

I hope we will find some clarity in the forecast in a day or two, but as of right now the forecast is a mess because the timing of the front is so close to race day.

(Space City Weather is sponsored by Westbury Christian School for this month)

Given how cold it is this morning across Houston, it’s difficult to imagine warmer temperatures, but the region will indeed warm into the upper 70s by late this week. If you’ve been reading my long-range forecasts for the Houston Marathon, on Jan. 15th, you’ll know that my concern has been that the majority of model guidance has been indicating the heat won’t “break” before race day. However, over the last 24 to 26 hours the forecast models have been shifting their outlook by bringing the next front through sooner. Therefore, although the forecast remains uncertain, there is some cause for optimism. Let’s take a closer look.

GFS model

As has happened a lot this winter, the GFS model has flip-flopped on its forecast in the 7-10 day time frame. During three of the last four model runs the model has brought a cold front through the region on Saturday, Jan. 14th, which would of course be excellent news. If this scenario plays out, we could conceivably see race-time temperatures in the low-40s, with highs in the mid-50s.

This is a nice change from the previous outlooks, but I want to stress that the timing of the cold front remains far from locked in—and a cold frontal passage on Sunday at noon does us runners no good.

The European model

The ECMWF model has also trended colder, but again it boils down to the timing of the next cold front. About half of the ensemble members bring the front in before the beginning of the race, and about half bring it in on Sunday around noon or later. Therefore the European model has a range of low temperatures at race time from 35 to 65 degrees. That’s not very clarifying, is it?

Given the uncertainty, here’s my current thinking is on conditions at the start line:

Temperatures below 50 degrees: 50 percent

Temperatures from 50 to 60 degrees: 25 percent

Temperatures above 60 degrees: 25 percent

Precipitation: Rain chances will be dependent upon the timing of the front. If it comes through on Saturday, Sunday morning should be dry. But if the front pushes through on Sunday, it could make for a messy, wet race day.

Posted by Eric at 9:20am CT on Saturday

Wow! It’s really cold across the region this morning, with a 21-degree mark at Bush Intercontinental matching Jan. 17, 2014, as that site’s coldest temperature in the last half decade. The entire metro area (except for Galveston Island) is in the teens or 20s this morning, including sub-25s for much of the central Houston area. Wind chills across most of Houston are about 10 to 15 degrees.

It doesn’t look as though we’ll set records for low temperatures today, as that’s 19 degrees for both the Bush IAH and Hobby Airport locations, set in 1970. But this is very cold nonetheless.

Conditions today will understandably be cold, despite the clearing skies. The high temperature today will struggle to reach 40 degrees and a northerly breeze will make things feel cold all day long.

(Space City Weather is sponsored by Westbury Christian School for this month)

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