As expected, a very strong cold front has moved through Houston this morning, and we’re in for a potentially messy day as precipitation falls on and off the day until about sunset. As of 5:45am CT we are already seeing a wintry mix over northwestern Harris County and Montgomery County. More freezing rain and sleet will move into the area later this morning as the freezing line moves from north of Houston, through the city, and down to Galveston by around noon.

Essentially, as the air cools down, the region is likely to see a progression from rain, to freezing rain, to sleet, to snow. This is largely driven by the depth of the warm air, which will decrease throughout the day as cold air moves into the region from the north. Here’s a graphic showing under which conditions each type of wintry precipitation falls.

(National Weather Service)

Our concern for today in Houston, and the reason why schools and some businesses closed, is because of the transition from rain to freezing rain, which has the potential to very quickly ice over roads. Now, let’s take a detailed look at what may transpire later today.

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Winter Storm Warning issued for most of Houston

Posted by Eric Berger at 6:37 PM

Schools are closing for Tuesday, and given what we know about the forecast, that seems a sensible precaution. Already, the National Weather Service has issued a winter storm warning for the entire metro area along and north of Interstate 10, and this effectively means there is a significant potential for snow and ice accumulation.

(National Weather Service)

Basically, a mess is coming. The cold front arriving between midnight and sunrise on Tuesday seems to be a little bit colder than advertised, and this means that a freezing line should move through Houston earlier than expected, perhaps within an hour or two of sunrise. And that means the potential for freezing rain—the worst of all kinds of winter precipitation because it makes roadways incredibly slippery even with slight accumulations—will move into Houston around the same time.

Road crews are treating freeways and other major arteries with a salt-based solution that lowers the freezing temperature of water and could help some, but under the present forecast we can still expect some bridges and overpasses to freeze, in addition to untreated roads. In short, if you don’t have to get up and drive to work on Tuesday morning, don’t. If you run a business, please consider giving your employees the day off. It is by no means certain that some or many Houston roadways will be icy Tuesday morning or midday, but at this point there’s a pretty good chance.

The precipitation, some of which may transition from freezing rain to sleet or snow later on Tuesday across Houston, should end by the afternoon or evening hours. But with temperatures remaining below freezing, and depending on how much rain falls, roads may not improve much after the precipitation stops during the evening and overnight hours.

We will have a comprehensive update by 6am CT on Tuesday.

Latest on winter storm event for Houston on Tuesday

Posted by Eric Berger at 12:35 PM

Just wanted to provide an update on conditions for Tuesday, especially because it now appears as though any freezing precipitation may move into the city a little earlier than expected. I know there are a lot of people and organizations out there looking to make decisions, so as of about 12:30pm CT on Monday, here’s what we know: A cold front is still on track to move through Houston between midnight and sunrise on Tuesday. The key questions are how cold it will get, how soon, and the timing of the precipitation. Here’s a look at what may happen at certain times.

Midnight-6am Tuesday

In the map below we see a mix of sleet and freezing rainfall moving from the northwest into the Houston metro area. This forecast from the GFS model shows accumulations for the 6-hour period from midnight to 6am, and they are slight. However when it comes to freezing rain (shown in pink) it doesn’t take much to cause problems on roadways, especially bridges and roadways.

GFS model forecast for midnight-6am accumulations. (Weather Bell)

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Houston may face yet another winter storm this week

Posted by Eric Berger at 7:40 AM

After a clear and cold weekend, our concerns once again turn to the possibility of a winter storm in Houston—the third time we’ve worried about this kind of thing during the winter of 2017-2018. Fortunately, I’m also pretty confident this is the last time we’ll have to worry about this for this winter.

MLK Day

Fortunately, the inclement weather will hold off for today, allowing for pretty nice conditions across the region for the celebration of MLK Day. We can expect to see high temperatures in the low 60s, with partly sunny skies. Some scattered showers are possible later this afternoon and evening, as temperatures fall to around 50 degrees.

Tuesday

Everything changes on Tuesday as a strong cold front blows into Houston between midnight Monday, and sunrise on Tuesday. Light rain should follow behind this front. We’re not concerned about accumulations, with only a tenth or two of an inch of precipitation for most areas. But we are definitely concerned about the potential for rain turning into a wintry mix north and west of Houston on Tuesday morning (i.e. in the Brazos Valley and the Piney Woods regions), and moving southward into the Houston area later on Tuesday.

GFS model for precipitation from 6am to noon Tuesday. Rain for southern half of Houston, with mostly sleet (ice pellets) to the north. (Weather Bell)

Expect temperatures to fall throughout the day on Tuesday as very cold air advects into the region behind the front. For Houston, we’re primarily concerned about precipitation that lingers into the afternoon and evening on Tuesday, when temperatures fall below freezing. Although the precipitation (rain, sleet, snow?) will be light, you’re going to want to check the weather and road conditions before venturing out on Tuesday evening or Wednesday morning. Overall I’m not too concerned as something like light sleet shouldn’t cause major problems. But we’re nonetheless watching this closely because of its trouble-making potential, and we’ll keep you updated. A winter weather advisory is in effect from 3am Tuesday until 6am Wednesday for the entire metro area.

GFS model for precipitation from noon to 6pm Tuesday shows sleet over most of Houston, with snow up north. (Weather Bell)

The other big story for Tuesday night is low temperatures. Right now I expect we’ll see low 20s for inland areas, mid-20s for central parts of the Houston area, and upper-20s for the coast. Obviously you should take similar precautions as to what you did for the cold snap right at the beginning of the new year.

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