HOUSTON - When the high temperatures in the northern tier of states are colder than that of the surface of Mars, you know you're in for a blistering arctic punch. Highs in the Dakotas and Minnesota are progged to be in the -10 to -20°F range while the surface of Mars (some parts anyhow) are a "balmy" -9°F (daytime highs only, near the equator). These are minor details but important!
Get ready. The cold is on its way to Houston and there's nothing in its way to stop it.
Sol 1917 (Dec 27, 2017), Sunny, high -19C/-2F, low -80C/-112F, pressure at 7.86 hPa, daylight 05:48-17:31— Mars Weather (@MarsWxReport) December 30, 2017
While temperatures won't be that cold in Houston, it'll be blistering cold by our standards for sure with high temperatures struggling to get above freezing Monday and Tuesday.
The kind of cold snap that we're about to experience is not unusual in southeast Texas. This area has a long, storied history of severe freezes (far worse than what's coming) in the recent past. As recently as 1983 and 1989 featured temperatures in the single digits and low teens with highs in the 20s. We won't be that cold this time around.
The coming cold will pale in comparison to the freezes of yesteryear but given the long stretches of time between such events makes it just as dangerous -- especially given the amount of homes still being rebuilt with no insulation. Take this freeze seriously. Your pipes will burst and your plants will be walking towards the light if they are not protected!
The arctic front is due in on Sunday morning. The daytime high for the day will be set in the morning. Temperatures will drop and continue to fall throughout the day, dropping us into the mid 40s by mid afternoon and many areas below freezing by midnight.
Some areas of southeast Texas may not get above freezing Monday. These areas would be for the far northern sections including Madisonville. Areas further south will struggle to reach above freezing but will likely do so into the mid 30s.
By Tuesday, the possibility exists that all areas north of I-10 could remain at or below freezing all day long. Overnight, temperatures will drop into the upper teens north of I-10 and low to mid 20s inland from the immediate coast and around 30 degrees in Galveston.
It's possible that there could be five consecutive nights of at or below freezing for many areas inland from the beach.
How Low Will It Go?
The coldest temperatures are expected Monday and Tuesday nights with the most wicked temps expected by early Wednesday morning. Mid to upper teens look like a good bet for the northern counties while low to mid 20s look like the best bet for areas south of I-10 with the immediate coast staying in the upper 20s to near 30 at that time.
Wind chills will be a really big deal. Wind chill values will hover between 0° and 15° above zero (scary that I have to designate that, right?). Hypothermia may be an issue for those left outside. We at KHOU and those at the National Weather Service can't stress enough how serious the cold temperatures can be.
What Needs To Be Done?
Protect anything and everything. This is a significant freeze by Houston standards. Anything that begins with a "P" definitely needs protecting including: pipes, plants, pets, pools, people as well as backflow preventers.
As the coldest weather settles in, leave the cabinet doors in your home open to allow the heat from the home to insulate the pipes. Keep a slow drip going overnight. Moving water is harder to freeze than standing water.
Finally, still have those Christmas lights up that aren't LED? Keep them burning! Wrap them around plants and then cover them with a sheet. The sheet must touch the ground to help trap any heat being released from the ground. If the sheet doesn't touch the ground then all you've done is put a funky looking ornament over your plant that offers zero protection.
Hypothermia could be an issue if you're left outdoors. The best way to combat the cold temperatures is not with one heavy jacket but many layers. They don't have to be heavy or thick. Several t-shirts under a sweater and jacket will do you just fine. Long underwear for your legs, gloves, hats, scarfs and earmuffs will also be needed.
Please, please, PLEASE bring your pets in. It is not fair to leave them outside in such extremes. Their fur is not thick enough to protect against those kinds of temperatures, especially overnight. If you insist on leaving them outdoors, make sure their dog house has hay or several thick blankets that they can snuggle up in.
At this time it appears as though any precipitation ahead of the front will shut off before our surface temperatures reach freezing. The problem will be if there is any water left on the roadways by Sunday night after midnight. If so, we could see elevated areas become slick with ice but that appears to be a very minimal chance.
Some models continue to try and spit out a few flakes of snow, the atmosphere will likely be far too dry to allow any dendrites (snowflakes) to make it to the surface before evaporating. Therefore we are not looking for any wintry weather here at all.
How Extreme Is This Freeze Anyway?
If you're from Pittsburgh, Chicago or Cleveland then the answer is not very. If you're a long-time Houstonian, then this is about as cold as it gets without totally going overboard like it has done a few times over the last 100 years.
In the grand scope of things, this freeze is colder than most but hardly historical. Let's not get carried away here. In fact, last January the temperature at Bush-Intercontinental plunged to 21° and 23° on two consecutive nights.
This freeze will be a degree or two colder than that. If we drop less than 20° at IAH then it'll be the coldest temperatures observed in the city in 21 years (Jan. 8, 1996 was the last time). Even then 19°, my current forecast low for Tuesday night/Wednesday morning, will only be tied for the 5th coldest temperature in the last 30 years and hardly a blip in the record book if you go back a hundred or more years.
The coldest temperatures ever observed here are 5 degrees in 1930 followed by 6 degrees on two consecutive nights in 1899, 7 degrees in 1989 and 11 degrees in 1983. We will not be that cold; guaranteed.
Even if the city of Houston does manage to stay below freezing on Tuesday (and that's a big IF), it still makes me yawn. The longest duration freeze in the city is 123 hours (over 5 days!!) back in 1951.
The coldest months for southeast Texas are still ahead of us. February has offered up some of the most superlative winter weather we've ever seen here in Houston. Could this freeze be a dress rehearsal for something more later? I wouldn't bet against it. Only time will tell.
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