Sunday morning update: Snow likely tonight for much of Houston, followed by extreme cold

Good morning. Today is the last day most of the Houston area will see above-freezing temperatures until Wednesday. We have a section at the end of this morning’s post about preparations for the upcoming hard freeze, this really is your last opportunity to do so. After today, Houston’s weather is going to be full on winter until at least Friday.

We’re going to discuss this in three phases: Winter storm on Sunday night into Monday, Extreme cold on Tuesday morning, and a Second Arctic front on Wednesday through Friday morning.

Sunday and Monday

Today will be far from pleasant, but for most of Harris and surrounding counties, temperatures through at least the early afternoon should remain above just above freezing. Additionally, any precipitation that falls before around 4 to 6pm this evening should do so as rainfall. (Note: you don’t have to get too far west of Katy, or too far north of Conroe, before you run into freezing rain today). By late afternoon or early evening, temperatures should begin to drop below freezing across the area, from west to east as an Arctic front moves into Houston.

This front will have two immediate effects. From sunset on Sunday to sunrise on Monday, temperatures will plunge into the low 20s across the metro area. And it will bring a healthy dose of precipitation to the region. If this were to fall as rain, it would be about half an inch for most locations, but due to the cold temperatures, we’re going to see some form of winter precipitation. But what kind? We talked yesterday about how, for snow to reach the ground, temperatures must remain freezing from the surface all the way to clouds where precipitation forms.

Current National Weather Service snowfall forecast for Sunday night. Subject to change! (Weather Bell)

On Sunday evening, the atmosphere is unlikely to be below freezing all the way up, so I think most areas will see a glaze of freezing rain fall before it turns to snow. We’re now reasonably confident that areas north of Interstate 10 will see on the order of 1 to 4 inches of snowfall by around mid-morning on Monday. We’re less certain what will happen closer to the coast, where there may be enough lingering “warm” air from the Gulf of Mexico to produce sleet or more freezing rain rather than snow.

The forecast models now suggest this precipitation will end by mid-morning, as the atmosphere dries out. We still can’t have complete confidence in what area roadways will look like, but the potential for a glaze of ice on the surface, covered over by snowfall, is a rather dangerous one. You should be prepared to not go anywhere from Sunday evening through Tuesday morning. Some major roadways may be cleared by authorities, but this kind of winter storm is unprecedented in recent decades because temperatures on Monday will not get high enough to melt roads. Rather, daytime temperatures will remain in the low to mid-20s. So anything that falls, will stick.

Monday night and Tuesday

We still have lots of questions about the severity of cold weather on Tuesday morning, but if the snowfall forecast verifies for Houston it will amplify the cold weather. The combination of snow cover, light winds, clearing skies and an Arctic air mass is pretty much about the most ideal conditions you could conceive for cold temperatures in Houston. However if the region gets more sleet or freezing rain, and clouds linger, temperatures could be somewhat warmer.

As a result, I think we’re looking at a range low temperatures from 5 to 15 degrees for western Harris County and Montgomery County, 10 to 20 degrees in central Houston, and 15 to 25 degrees along the coast. As Matt discussed yesterday, this would be a historic cold snap for the region.

Sunrise temperatures on Tuesday morning. (Weather Bell)

Another question we have is where temperatures may briefly rise above freezing on Tuesday. The coast is a definite yes, where highs may reach the upper 30s. Many areas south of Interstate 10 may briefly see highs of 33 degrees or slightly warmer. I do not know whether this, in combination with mostly sunny skies, will be enough to melt and dry roads. Much of the region north of Interstate 10 will remain below freezing during the daytime. Temperatures Tuesday night will only drop a little bit below freezing.

Wednesday and beyond

Part three of our collision with winter will come later in the week. Yet another storm system will approach from the west early on Wednesday, and it will draw Gulf moisture into the region. Much of the Houston metro area is likely to see another 0.5 to 1.0 inch of precipitation on Wednesday. This may start out as freezing rain early in the morning, but as daytime temperatures climb to about 40 degrees, it should turn to rain. This should also melt any lingering ice on roads.

However, temperatures on Wednesday night will probably drop below freezing for everywhere but the coast, so this sets up a situation where roads are problematic again on Wednesday night and Thursday morning due to ice. We’ll have to nail down these details in the coming days. Highs Thursday should rise above freezing and will hopefully melt any ice on the roads, but we’re going to remain close to freezing. Again, details to come on this.

Friday morning should produce the last freeze of the week (and perhaps of this winter?) (Weather Bell)

Highs Friday should finally push at least into the mid-40s, with sunny skies. That will be the end of the winter storm. By Saturday, we should be into the 60s.

Final preparation tips

These suggestions were provided by Jeff Lindner, a meteorologist with the Harris County Flood Control District.

PIPES: Protect all and any exposed pipes, shut off and drain sprinkler systems. Open cabinet doors and closet doors to get as much heat against outside facing wall pipes as possible starting Sunday night. In some cases the best course of action may be to shut off water to a structure and drain pipes overnight when water usage is low to avoid pipes freezing and bursting.

PLANTS: Heavily cover and protect any tropical vegetation, citrus, or vulnerable plants. Given the intensity and depth of the freezing conditions this will likely be a killing freeze for much of the tropical landscape of this region.

PETS: Pets and livestock should have proper shelter, feed, and water. Normal water supplies will likely freeze over including stock ponds and lakes.

PEOPLE: Persons should plan to limit outdoor exposure Monday and Tuesday as wind chills will be dangerously cold for our region. Prolonged exposure could result in frostbite and hypothermia. Please ensure your neighbors have adequate heating.

Matt will have our next update on the site by around 4 or 5 pm CT today.

Looking back at some previous historic Houston cold snaps

With the deep freeze on the way to Houston, Eric thought it would be a good idea to take a look at some previous significant cold in Houston, so we can place this outbreak in historical context. As Space City Weather’s unofficial history guru, I’ve taken on the challenge!

Quick forecast update

Eric’s morning post does a nice job discussing what we know and expect over the coming days. Not a whole lot has changed, though I think three things stand out.

1.) First, there is a real chance that there could be some freezing drizzle or light freezing rain overnight tonight and Sunday morning. Please check with us or other local outlets if you are planning to travel anywhere tomorrow morning.

2.) Second, the start time of Sunday evening’s precipitation has sped up a bit, and we may see rain or freezing rain or sleet begin as early as 3 or 4 PM on Sunday.

3.) It seems colder air may push in here a little faster on Sunday night and Monday morning. This is both good and bad. It’s bad in the sense that we’re likely to endure a longer stretch of temperatures in the mid-20s or colder. It’s good, however, in the sense that this might lead to more sleet (or snow) and less freezing rain. Forecasting precipitation types is extremely challenging, as Eric noted this morning, so I expect more curve balls to be thrown our way between now and tomorrow evening, but at least this afternoon, it looks like sleet may be the more common precipitation type we see tomorrow night. We’ll have more for you in the morning.

February 2021

So, to begin our trip through history, let’s set the table with the current cold outbreak.

Current coldest forecast temperature: 10° on Tuesday 2/16
Nights forecast at or below freezing: Five

The current official NWS forecast low for Houston on Tuesday morning (at IAH Airport) is 10 degrees, which would rank as a tie for Houston’s 5th coldest morning all-time (back to 1889). Since official records have been kept at Bush Airport (1969), this would rank as the second coldest, with only December 23, 1989 being colder (7 degrees).

Some may try to talk down this cold outbreak because of its less impressive duration than, say, 1989 which saw three of Houston’s 25 coldest mornings on record. However, the current Monday through Friday forecast (as of Saturday afternoon) shows an average temperature of 28.5 degrees for the 5 day period. This would rank as Houston’s 12th coldest 5 day stretch on record. If that does verify, it will be our coldest 5 day stretch of weather since 1983. So this certainly qualifies as an upper echelon, if not historic cold snap.

So let’s look back at some other memorable Houston cold snaps through the years.

January 2018

Coldest temperature: 19° on 1/17
Nights at or below freezing: 10, split up over 20 days

We’ve gotten a few comments from folks questioning how this upcoming cold could be classified as “coldest in years” when we just had cold like this in January 2018. Well, the reality is that January 2018, while impressive, was split up over 3 weeks and came with comparatively mild daytime highs.

January 2018 had its share of cold, including our coldest morning since 1996, but we weren’t able to string together a stretch quite like this week. (NOAA)

We did hit 19 degrees, which at that time was our coldest low temperature since 1996. We managed to reach the upper 30s on both days, which isn’t overly impressive. That event also came with snow, sleet, and ice. Impressive, but probably not historic.

February 2011

Coldest temperature: 21° on 2/2
Nights at or below freezing: 12 over 2 weeks

Another one we hear about is 2011. I remember February 2011 vividly because I moved to Houston for a time that month and arrived at the end of January. Quite the welcome. Houston officially bottomed out at 21 degrees on February 2nd. We registered 5 straight days with lows in the 20s from February 1-5 and 4 days from February 9-12. There was also an ice storm of sorts on the 4th. Eric wrote about it at the Houston Chronicle. I actually remember forecasting this and it being a really good lesson in the challenges of forecasting winter weather in the South.

While this was not really a record-setting event in Houston, other parts of Texas saw some impressive records. El Paso’s coldest February day on record was February 3, 2011. Dallas was plagued with cold and wintry weather as well, marring the 2011 Super Bowl.

December 1989

Coldest temperature: 7° on 12/23
Nights at or below freezing: 14 over 2-3 weeks

In pantheon of modern Houston cold snaps, December 1989 is front and center.

The front page of the Houston Chronicle from December 23, 1989, the day after Houston officially recorded 1.7″ of snow and the day that Houston recorded the coldest December day on record. (Houston Chronicle)

Six record low temperatures still stand from 1989.

December 12: 25°
December 13: 19°
December 16: 19°
December 22: 13°
December 23: 7°
December 24: 11°

December of 1989 was Houston’s coldest December on record back to the 1880s. Between crop losses and other damage, the cold of December 1989 was estimated at the time to cause $300 to $500 million in damage (up to $1 billion in 2021 dollars) in Southeast and Coastal Texas, according to NOAA’s December 1989 StormData publication. This event merits a whole post on its own, which we’ll hopefully one day get to!

December 1983

Coldest temperature: 11° on 12/25
Nights at or below freezing: 12, including 11 in a row to close the month.

The December 1983 cold wave was another hall of fame event for Houston. We closed the month with 11 straight mornings below freezing, including four full days that failed to crack above 32 degrees.

The Christmas morning Houston Chronicle featured pictures of fountains turned into ice sculptures in Houston. (Houston Chronicle)

The 1983 cold snap caused an estimated $50 to $100 million in damage in Texas at the time (up to about $250 million today). December 1983 is Houston’s second coldest December behind 1989. December 1983 was to Dallas what December 1989 was to Houston, leading to their coldest December on record.

January 1978

Coldest temperature: 21° on 1/20
Nights at or below freezing: 20 (!) over the course of the month

The January 1978 cold snap doesn’t have much intensity on any single day, but it makes up for that in terms of duration, which ultimately led to 1978 being our coldest January (and coldest month) on record.

Frequent fronts ushered in cold, Arctic air through most of January 1978, which led to a low to moderate intensity, but sustained cold air outbreak over Houston. (NOAA)

The 1970s had some pretty amazing winters across the United States, and for Houston this was almost certainly the peak. Although, 1973 saw four days of snow in Houston between January and February.

January-February 1951

Coldest temperature: 14° on 2/2
Nights at or below freezing: 6 in a row

January 1951 started off quite mild with 14 days in the 70s. The switch flipped on January 28, when temperatures dropped 40, and then January 29 when they kept dropping to 24 degrees. We then had four straight days below freezing all day long. The January 29-February 3 period remains Houston’s coldest stretch of 6 days on record, averaging 26.3 degrees.

January 30, 1951 front page of the Houston Chronicle, one of several days that saw the region dealing with disruption and damage due to ice and excessive cold. (Houston Chronicle)

In addition to the cold, what is likely the worst ice storm in city history led to serious damage and disruption. Almost an inch and a half of precipitation fell during the cold snap. Another event likely worthy of its own post.

January 1940

Coldest temperature: 10° on 1/19
Nights at or below freezing: 11 in a row

The 1940 cold snap came with snow on January 22nd, with up to 3 inches reported from Houston into southern Louisiana and more elsewhere in the states. Only twice has Houston seen 11 straight days of low temperatures at or below freezing: January 1983 and January 1940. The 1940 cold is notable for both intensity and duration.

January 1930

Coldest temperature: 5° on 1/18
Nights at or below freezing: 8, coming in two 4-day waves

January 18, 1930 is Houston’s coldest morning on record, with a low of 5 degrees above zero. The cold came in two punches, this first strong one, followed by a second one a couple days later in which we bottomed out at 15 degrees on the 22nd.

The January 18, 1930 Houston Chronicle trumpeting the news of Houston’s coldest recorded day. (Houston Chronicle)

Five days after hitting 15 degrees, we were back up near 70, so further proof it won’t stay cold forever!

February 1899

Coldest temperature: 6° on 2/12 and 2/13
Nights at or below freezing: 9 in a row

The February 1899 cold snap covered most of the eastern half of the United States, and it could be deemed the granddaddy of them all in the South. Several records from that event still stand today, including the coldest on record for Amarillo (-16°), Dallas (-8°), Galveston (8°), and the Texas all-time record (Tulia was -23°, a record shared with Seminole in 1933). In addition to Texas, state records still stand or are shared today from this cold snap in Nebraska, Ohio, Louisiana, and Florida.

The February 13, 1899 edition of the Houston Post described the cold snap thusly:

“When a younger friend approaches him now and suggests to him, with a degree of profanity based on the length of time he has been exposed to the chilling, biting, nipping North wind, that ‘it’s pretty cold,’ the oldest inhabitant cannot yawn, draw closer to the welcome fire, and say, with an air of conscious superiority, ‘Yes, but away back in ’73 there was a norther that–.’ He has no recourse but to moodily assent, put a few more coals in the blazing grate and reflect on what has been, what might have been and what may be. And all this makes him sad, very, very sad.”

February 1899 is front and center in the pantheon of cold as well.

February 1895

Coldest temperature: 10° on 2/8
Nights at or below freezing: 12 over the course of 2 weeks

February 1895 was a memorable cold snap, with 4 daily records still standing today. But what set 1895 apart for Houston was our greatest snowstorm of 20 inches, which we conveniently wrote about back in 2017!

The final word

So, will 2021 join these memorable cold snaps? Probably. But ultimately, whether it really can join the ranks of a 1989 or 1983 or 1899 will depend on just how cold it gets Tuesday morning.

Here’s the latest on Houston’s winter storm and exceptional cold

Good morning. Before jumping in to the forecast, I wanted to spend just a moment discussing why some areas of the region will see snow on Sunday night and Monday, and others sleet or freezing rain. It has to do with the temperature in the column of air above the surface, through which precipitation falls.

Snowflakes form high in the atmosphere, and if the temperature remains below 32 degrees as they fall thousands of feet to the surface, they remain snow. However, if there are pockets of warmer air and then sub-freezing temperatures again, sleet will form as snowflakes, melt, and then re-freeze as small ice pellets. And finally, if there is warmer air near the surface, but not at the surface, we’ll get freezing rain. The graphic below helps depict these processes.

How different types of winter precipitation form. (National Weather Service)

This is the primary reason we think freezing rain is most likely near the coast—where the Arctic air mass will be most modified by the warmer Gulf of Mexico near the surface—and snow most likely over areas well inland. In terms of roads and potentially power lines, freezing rain is most problematic because it only takes a little to stick to roads and make them icy, and not that much more to accrue on power lines and weigh them down, or become more susceptible to blowing winds.

We’re starting to get closer to Monday, so higher resolution models are beginning to come into our forecasts, and as they do so confidence in which types of winter precipitation, and how much will fall, will increase.

Saturday

Temperatures are above freezing across the Houston area this morning, but only barely. They won’t rise a whole lot today, likely only reaching the upper 30s in Houston, and near 40 degrees along the coast. Buy hey, that’s better than freezing, right? In terms of wintry precipitation, our concerns now begin tonight for parts of the metro area northwest of a line from Katy to Tomball to Conroe. This is because lows for those areas are now expected to fall to about 30 degrees. This, in concert with light precipitation, could lead to some icing on elevated roads and bridges.

Sunday

Highs on Sunday should get into the mid-30s for even these inland areas, and warmer in Houston itself, so traveling across the metro area after mid-morning on Sunday should be fine. But the further west and north you go, you’re still going to run into freezing conditions.

Conditions begin to deteriorate by around sunset on Sunday in Houston. This is when we expect widespread precipitation to move into the area, and temperatures to begin to fall below 32 degrees. Some inland areas won’t see above freezing temperatures again until Wednesday.

Freezing temperatures begin to reach northern and western Houston by sunset on Sunday. (Weather Bell)

Sunday night and Monday

This is when conditions on area roadways will become treacherous. As noted above, we expect snow to fall across inland areas where temperatures are the coldest, but we don’t know where snow will switch to sleet, only that this line will likely be somewhat north of Interstate 10. In terms of accumulations, here is our best forecast at this time, but it remains highly subject to change as additional high-resolution forecast models enter the picture.

Snowfall: For areas that receive it, about 1 inch, with 2 or more inches possible for Conroe and areas north of there.

Sleet: About 1 inch for central parts of the Houston metro area, with less north (where there will be more snow) and south (where freezing rain is more likely).

Freezing rain: About one-quarter inch for areas along and south of Interstate 10.

It now appears likely that precipitation will wrap up by around Noon on Monday, if not shortly before. Unfortunately, because temperatures at that time will probably only be in the low 20s for most of the area, whatever falls on the roads is not going anywhere. Moreover, with winds gusting out of the north above 30 mph, especially along the coast, it will feel like 10 degrees or below. Finally, these winds could play havoc with iced over power lines. So yeah, Monday is a day to stay home and hunker down.

Tuesday

After the precipitation ends, skies may begin to clear overnight. With extremely cold air in place, this will allow for ideal cooling conditions heading into Tuesday morning. And it will be exceptionally cold for Houston. Areas where there is snow on the ground, well west and north of Houston, may see temperatures of 5 to 10 degrees, and the coast will only be marginally warmer, in the low 20s. (The all-time record low for Houston is 5 degrees, set in 1930.)

Forecast temperatures for 6am CT Tuesday. (Weather Bell)

Temperatures should reach above freezing, if barely, for areas south of Interstate 10 on Tuesday. But areas north of that line may continue to see freezing temperatures throughout Tuesday and Tuesday night. Lows will not fall much Tuesday night.

What this all means for roadways in the Houston for Tuesday morning and beyond is unclear. It will depend on how much precipitation falls Monday, in what form, and whether efforts to de-ice roadways are effective. I can offer no good predictions here, sorry.

Wednesday, Thursday, and Friday

Unfortunately, another round of precipitation is likely on Wednesday, as moisture moves inland from the Gulf of Mexico, and another front approaches. This will fall as rain on Wednesday, but for inland areas at least it could turn into sleet or freezing rain on Wednesday night—at least for areas along and north of Interstate 10.

The details of this are still very much in flux, but there’s a chance for more icy roads on Wednesday night and Thursday morning. At this time we do anticipate less impact than we’re likely to experience on Monday. Lows drop into the 20s on Thursday night, probably, before finally warming well above freezing on Friday.

And that’s the end. Saturday should get into the 50s or so, and by Sunday we’re back to highs in the 60s. Until then, it’s going to be absolutely frigid. Stay safe, y’all.

Matt will have a brief update on the forecast later today, and also take a first stab at historical significance of this kind of winter event for Houston.

 

 

 

Some Friday evening thoughts on Houston’s looming winter storm

Good evening. The overall forecast picture has not changed much today. We still expect a winter storm on Monday, with widespread problems on area roadways, followed by an extremely cold night and frigid Tuesday. Matt’s post from this morning still holds up well, but I just wanted to add a few more things that are becoming clearer as we get closer to the hard freeze.

There is still time to prepare

Conditions have fallen below freezing across much of the state, but most of the Houston metro area should remain above freezing until Sunday evening. That’s not to say it will be pleasant this weekend—highs are unlikely to rise above the low 40s, and there will be a chance of drizzle or light rain, especially Saturday night.

High temperatures on Sunday, which is your last day to prepare. (Weather Bell)

However, that means you still have the weekend to prepare for the winter storm, from wrapping your pipes or covering your garden for a hard freeze, to running to the grocery store. However, it now seems likely that by as early as Sunday evening light rain could turn to freezing precipitation. This means you should plan to be home, or wherever you’re going to hunker down, by around sunset on Sunday.

Monday looks pretty bad

Temperatures will fall below freezing Sunday night, and stay there for all of Monday, with the possible exception of Galveston and other beach locations. By tomorrow the higher resolution models should provide us more clarity on exactly what type of freezing precipitation will fall in Houston. But for the most part, we expect a mix of freezing rain and sleet in the city, with a greater likelihood of snow north of Houston.

Freezing rain would be the worst outcome, because as little as one-tenth of an inch will be enough to glaze over roadways. As more falls, it starts to accumulate on power lines, and that could eventually lead to power outages. Some recent models are leaning more toward sleet (ice pellets) than freezing rain, which would be good. We expect precipitation to end by early Monday afternoon, but with temperatures below freezing the ice isn’t going anywhere.

The bottom line: many if not all roads will be a mess either way, and you should stay home. If you’re an employer, you should at the very least tell employees to come in late on Monday, pending a final call. By early Monday morning we should have a better sense of just how bad things will get.

Models have trended slightly colder

If anything, the major models have trended slightly colder with lows on Monday night and into Tuesday morning. It now seems possible that areas of west Houston (i.e. Katy or Sugar Land) could see temperatures drop to around 10 degrees, with central Houston at about 15 degrees.

This is extraordinary cold. The all-time record low temperature for Houston is 5 degrees, set in 1930.

Current forecast for low temperatures on Tuesday morning. (Weather Bell)

I would caution that there is still some wiggle room in the temperature forecast. There are a couple of factors that will ultimately determine lows on Tuesday: extent of snow cover, if any; whether clouds clear out before sunrise, and how calm winds become. But we are highly confident in a very hard freeze for the entire area.

When does this end?

Something else we’re trying to track is when this mess ends. It now seems pretty clear that any roads iced over will remain so through Tuesday night given the cold temperatures. The big question is whether temperatures will warm up enough on Tuesday to melt any icy or snowy roads.

There is not much agreement on this in the forecast models, but for now I think at the very least areas along Interstate 69, and closer to the coast, will warm to above freezing levels. I’m less certain about west and northwest parts of the metro area. Wednesday should bring above-freezing temperatures back to the area.

However, yet another front will bring more Arctic air into the region toward the end of the work week. We think there is a chance of yet another hard freeze on Thursday or Friday morning, and we can’t preclude more of a wintry mix on Wednesday or Thursday. We are reasonably confident that temperatures will recover by next weekend. So if you’re looking for an end to the winter madness, it’s likely coming about seven days from right now.

We’ll have a full update on the forecast on Saturday morning.