Eric Berger

In brief: A winter storm has brought a mixture of precipitation to Houston overnight, including snow and sleet. This wintry precipitation will end later this morning, and we will see some sunshine and above-freezing temperatures this afternoon before a very cold night.

Storm status

The Houston region has received a mix of snow, sleet, and other forms of wintry precipitation during the overnight hours, setting up slick conditions on Houston area roadways. Total snow amounts have varied widely, from a fine dusting of ice and sleet in some locations to 3 inches or more elsewhere.

Additionally, it is quite cold outside this morning. Air temperatures are generally in the mid- to upper-20s for most of the Houston region. However the addition of brisk northerly winds, gusting up to 25 or even 30 mph from the north, have made it feel like it is in the teens outside.

With temperatures now well below freezing for much of Houston, what is falling is largely sticking to area roadways that have been untreated with salt. There are dozens of reports of ice on area freeways, feeders, and major roadways, some of which are shut down. You can track an list of Houston-area icy roadways on Houston Transtar.

In short, for some areas it is a winder wonderland outside, for some a sleet-fest, and for all a dangerous time to be outside. Please do stay home this morning if it is at all possible.

Tuesday

The latest modeling indicates that the precipitation we are seeing this morning will exit to the east by 9 or 10 am CT. We should then see some clearing skies early this afternoon across Houston, including the coast by later this afternoon. This sunshine should push temperatures toward the upper 30s, allowing for some of the ice and snow on the surface to melt.

Additionally, the combination of sunshine and windy conditions (from the north at about 15 mph) should begin the process of sublimation. Sublimation occurs when snow transitions directly into water vapor, without first becoming liquid water. I’m writing all of this because it is possible that some roads will become clear and dry this afternoon, especially for locations further from the coast where there will be a longer period of sunshine to work with.

This matters because temperatures are going to freeze again tonight. So if there is moisture on roads, it will freeze into ice tonight, and into Wednesday morning. This could lead to black ice or situations in which there are patches of icy, dangerous roads tonight.

The temperature tonight at your location will depend on how much snow cover remains. That’s because new snow has a very high albedo (up to 0.95 out of 1), which means it is highly reflective of heat (radiation) back into space. So locations where there is a snowpack tonight will be 5 or 10 degrees cooler than areas with “darker” surfaces not covered by snow.

Over the last couple of days we have watched as forecast models have really struggled with how cold temperatures will get in the Houston region on Wednesday morning. As a best guess, areas with a layer of snow may drop into the mid-teens tonight, and areas with less or no snow are likely to only fall into the mid-20s or so. My sense is that most of Houston probably will end up in the lower 20s, but we shall see.

Wednesday

After a cold start, high temperatures on Wednesday are expected to reach 40 degrees or even a little warmer under sunny skies. The combination of mostly sunny skies and sublimation should allow for roads to mostly dry out, but for some locations this may not happen until after noon. I realize the uncertainty is no fun, but such snow and ice events are relatively rare in Houston, so we are working on limited data about local roads and their response to icy conditions. Most of Houston will fall into the upper 20s on Wednesday night.

Thursday

A little warmer, with highs generally in the upper 40s to go along with mostly sunny skies. A light freeze is likely Thursday night.

Friday

Expect more sunshine, with highs in the 50s. Some inland areas may see a light freeze on Friday night, but most of us should be in the mid- to upper-30s.

Saturday and Sunday

Expect highs in the 60s this weekend, with nights only in the 50s as a warmer pattern returns. Saturday looks OK for outdoor activities, but rain chances start to increase by Sunday into next week.

Update schedule

We will have an update for you early this afternoon, by 2:30 pm CT, and again this evening to offer the best possible forecast for temperatures and roadways on Wednesday morning.

In brief: We are fast approaching the arrival of a winter storm, which is likely to begin with freezing rain or sleet late on Monday, and transition to snowfall early on Tuesday morning. Although we still have some questions about the details, there is little question that large chunks of Houston are going to get frozen in on Tuesday due to icy roads.

The coast with the most

One of the emerging trends we’re seeing in higher resolution models today is a greater concentration of snow in coastal areas, including Brazoria, Galveston, and Chambers counties. Matt mentioned the possibility of blizzard conditions tomorrow on Galveston Island, and I think it’s distinctly possible. Winds are going to peak between midnight and noon on Tuesday, with gusts likely above 35 mph. When you add the likelihood of heavy snowfall, you have the potential for a once-in-a-lifetime winter storm on the upper Texas coast.

How much snow will I get?

Snowfall forecasts are really difficult. Why? Because 0.1 inch of precipitation in rainfall equates, roughly, to 1 inch of snow. So relatively small differences in total precipitation lead to rather significant differences in snow accumulation. With that in mind, it does look as though the majority of the Houston area is likely to at least see at least 1 to 2 inches on Tuesday between midnight and noon. But totals could run much higher.

There likely will be a band of heavier snow, perhaps up to 6 inches or even a little more. I think it’s more likely this banding effect sets up near the coast, or possibly even just offshore. However, it could also line up along Interstate 10. Areas further north, including The Woodlands and College Station, appear to be less likely to get multiple inches of snow on Tuesday.

How cold will it get?

One area in which the models are really struggling is how cold air temperatures will get on Tuesday night and Wednesday morning. There remains a wide variance, and most locations in Houston may get as cold as 15 degrees, or remain relatively warm, in the upper 20s. Some of this variance is due to how the models are handling snowfall totals. In any case, we will try to refine this forecast in coming updates.

When will we thaw out?

Most of the model data continues to indicate that high temperatures will reach about 40 degrees on Wednesday. This, along with ample sunshine, should help to melt and dry out our roadways. If moisture remains on Wednesday night, then it is likely to re-freeze on Thursday morning. However at this time my best guess is that roads are OK beginning Wednesday afternoon, and onward. But it’s something we’ll keep an eye on.

How historic is this?

I’ve been writing about weather in Houston for a quarter of a century, and I’ve never seen a winter storm setup like this. Parts of the region saw several inches of snow back in December 2004, but it was mostly a coastal event, with much of Houston seeing flurries at most. We probably have to go back to 1895 to find an winter storm event that exceeds what the region is likely to experience on Tuesday.

Update schedule

Our next update will come this evening, no later than 10 pm CT. Then we will have full coverage for you on Tuesday, starting before sunrise. Please be safe and warm!

In brief: Houston is less than a day away from the onset of a winter storm that is likely to cripple transportation around the region. We’re still expecting primarily snow, with impacts on roadways through Wednesday morning. Expect two additional updates today on Space City Weather as we share what we know, when we know it.

Cold update

As anticipated, temperatures this morning have fallen a couple of degrees below freezing across the metro area. Fortunately, you still have today to prepare for a winter storm that will very probably bring more snow into the Houston region than we have experienced in at least two decades. The city is likely going to shut down from this evening through Wednesday morning, and it really should do so because we are ill-equipped to handle this kind of winter storm.

Before jumping into the post, I also want to thank the organizers of the Houston Marathon, as well as all of the thousands of volunteers and tens of thousands of spectators who make this such a special event. Yes, it was cold on the course on Sunday, but honestly after a mile or two the colder air felt great. It also feels great to be able to set aside my running shoes for awhile.

Monday

It is MLK Day, which honors the legacy of the civil rights leader Martin Luther King Jr. For kids, it’s a day off of school which, in addition to ‘snow’ days on Tuesday and Wednesday, makes for a five-day weekend. Not bad. It’s almost enough for me to wish I was seven years old again. Almost.

Anyway, today will be a brisk day with increasing clouds and high temperatures of around 40 degrees. A gusty easterly wind will add to the misery. We’ll see a slight chance of showers by around sunset this evening, but for the most part this should be rain in the Houston metro area. Please do plan to be wherever you’re sheltering from the storm this evening by about 8 pm for northern areas such as The Woodlands, and midnight at the absolute latest for central and southern parts of the Houston area.

Monday night and Tuesday

By around midnight temperatures in the region will reach freezing for most of Houston, and light rain will begin to transition to snow, sleet, and possibly freezing rain. The intensity of these snow showers or sleet will pick up on Tuesday morning. Low temperatures will drop to between 25 and 30 degrees for most of the region.

So what will you wake up to? I anticipate that most of the area will see 1 to 4 inches of snow, with some sleet mixed in by mid-morning on Tuesday. We still have some serious questions about the amount of precipitation, and I agree with Matt that there is a decent chance that some parts of Houston receive up to 4 to 6 inches. (Currently the favored region for this is probably along and south of Interstate 10, but we shall see). In any case, this should be wintry setup for which Houston-area roads are not prepared for.

Temperature wise, Tuesday is going to be interesting. The precipitation will end by around noon, and I expect we’ll see clearing skies during the afternoon hours. Temperatures will probably briefly get above freezing during the afternoon hours, and this may cause some of the snow and ice on the roads to briefly melt. However this window will be brief, as temperatures drop to below freezing by around sunset again. It will be a very cold night with slick streets.

Wednesday

How cold will it get? That will depend on the extent of snow cover where you are. I think most of Houston will fall to around 15 to 25 degrees, so a hard freeze all around expect perhaps for the immediate coast, such as Galveston Island. Air temperatures will likely reach above freezing at some point on Wednesday around noon. Then, sunny skies and temperatures in the upper-30s, at least, should help to clear roadways during the afternoon hours. By this time it should be possible to resume somewhat normal activities around the region. But we’ll need to see how the mobility situation plays out.

Thursday and beyond

Lows on Wednesday night will drop into the mid-20s in Houston, so another cold night. However by Thursday afternoon we’ll be well into then 40s. A light freeze is possible again Thursday night. The weekend looks mild, with temperatures climbing back into the 60s. A chance of rain returns by around Sunday, or so.

Best sledding in Houston

It’s kind of insane, but we’ve reached the point where we can legitimately talk about sledding here. Now Houston is a pretty flat city, so there are not a lot of great hills. But there are a few, such as the hill at Miller Outdoor Theater in Hermann Park. However, when choosing a locale for sledding on Tuesday (and possibly Wednesday) it would be foolish to choose a spot you have to drive to. Since we’re not going to be driving around on Tuesday, are we? In reality the best place for you to sled in Houston the steepest hill you can walk to.

Which doesn’t lead down into a pond or a bayou.

Update schedule

We plan on having two additional updates today. One will come this afternoon, probably around 3 or 4 pm; and another later this evening when we should be able to provide real-time information on the developing winter storm.

In brief: It is the final hours before the Arctic freeze sets in, and we’ve got the latest information on what to expect in terms of cold and wintry precipitation, and when to expect it. The bottom line is that Tuesday and possibly Wednesday both look very iffy for traveling around Houston.

It could be worse

As I type this, the Houston Texans are kicking off against the Kansas City Chiefs in the Divisional round of the NFL Playoffs. Game-time temperatures are in the low 20s, with gusty northwesterly winds. By Tuesday morning the low temperature there is expected to be -1 degree Fahrenheit. So yes, Houston is going to get cold this coming week, but it could always be worse. Also, let’s go Texans!

Temperatures will soon begin falling

It’s fairly pleasant outside, with temperatures in the low 60s across much of the Houston region. But don’t be fooled. Winds are steady from the northwest, and as the Sun falls toward the horizon, temperatures will follow. Lows tonight will drop to around freezing in Houston, and with gusty northerly winds the apparent temperature will feel as if it is in the low 20s, at least tomorrow morning. So if you’re joining me at the Houston Marathon, bundle up, wear layers, and use the cold as motivation to go faster. Despite the cold start, Sunday will be fine in terms of getting out and about. Highs will reach the low- to- mid-40s with sunny skies.

MLK Day

Houston will likely see a light freeze on Monday morning, although some inland areas (i.e. along and north of Highway 105) could see lows drop into the mid- to upper-20s. But Monday should be mostly fine for any last minute preparations ahead of a winter storm. Highs will be around 40 degrees. I’m afraid it’s a dreary forecast for MLK Day festivities, with increasing clouds and gusty easterly winds keeping a distinct chill in the air.

Monday night through Wednesday morning

You should plan to be home by around 9 pm CT or so on Monday. Although temperatures probably won’t fall below freezing until a few hours later, we might start to see some light sleet or snow by around this time. Temperatures reach freezing levels by midnight or so, when precipitation coverage should also begin to increase.

This is the point of the forecast where we are still mired in uncertainty. The key questions are a) how much moisture will be available for precipitation to form and fall, and b) what kind of wintry mix will develop. Neither is answerable yet. For areas along and north of Interstate 10, I continue to think snow is the most likely option (perhaps 1-3 inches, or more), but we could see sleet mixed in. For areas south of Interstate 10, sleet may be more likely than snow, although we may still see some snow there. Further to the southwest, in Matagorda and Brazoria counties, we may see freezing rain as the dominant precipitation.

The bottom line is that when you wake up on Tuesday, some sort of winter wonderland (or nightmare) is going to exist outside. Snow/sleet/freezing rain is likely to continue through the morning hours on Tuesday, and possibly into the early afternoon. We may see some partially clearing skies by evening. However, temperatures will struggle to reach above freezing on Tuesday, and if they do in Houston it may only be for an hour or two. So I don’t think we’re going to get enough warmth to melt and clear streets.

Depending on how much snow cover there is overnight, temperatures in Houston will either be in the upper teens or lower 20s on Wednesday morning, which will be the coldest of the week. Virtually the entire metro area, aside from the coast, is likely to experience a hard freeze. This is going to help maintain ice or snow on area roads, and my sense is that Wednesday morning will likely once again be a no-go for traveling around the area.

By Wednesday afternoon, the combination of (slightly) above freezing temperatures and sunny skies will probably help clear roads. But it’s difficult to be certain of this right now.

The end

Highs finally get back into the mid- to upper-40s on Thursday, so at this time we think Houston will return to normal by that time. Next weekend looks to be fairly mild.

Will my power go out

Honestly, we can’t answer that. However, our supposition is that things probably will be OK in Houston in terms of electricity. ERCOT issued an update on Friday saying that while it is monitoring grid conditions closely, they are expected to remain “normal” during the upcoming winter weather. That means officials are fairly confident the grid will hold up during the colder weather. Additionally, Houston is not expected to get significant accumulations of freezing rain, which can build up on power lines and snap them. So, cautiously, we’re optimistic. But we will see.

Next update

Since I’m running the marathon tomorrow and will be cooked for the rest of the day, Matt will be covering on Sunday. We’ll have a morning and late afternoon update on the winter storm situation, similar to today.