HOUSTON - First, it's not going to snow. I hate to be "that guy" that seemingly takes it all away with the stroke of my wand but the truth is, I don't have that much power. David Paul stripped me of it long ago so blame him. More on the snow an ice that was to be at the bottom of this story.
I can tell you that it's about to get cold so I'm officially issuing a "cuddle alert" beginning as early as Saturday lasting all the way through Christmas. Ergo, those ugly Christmas sweaters and the matching pjs should get good use this year.
Arriving at the Christmas forecast has been difficult at best and getting this far has required much collaboration with the weather team and nearly an entire bottle of Aspirin. In fact, the last few forecasts have been put together by closing my eyes and throwing a dart. I kid of course. In reality, it's required lots of compare and contrast with different models as seen below:
The first of a series of fronts will move through late Friday night into early Saturday morning. This will spark a line of showers and thunderstorms that will rumble through while you sleep. Temperatures behind the front will fall and keep our highs on Saturday governed in the 50s under mostly cloudy skies.
Another front, the big front, will move through on Sunday and that will knock our high temperatures into the 40s for daytime highs for a few days before rebounding into the 50s and 60s by Wednesday and Thursday after Christmas.
If you're traveling north to Dallas, it's not out of the question that you may see a few flurries on Christmas Eve or Day but no accumulations are expected and it'll be just that: flurries. Hardley worth a mention.
Travel to Austin or San Antonio looks great as well but bring the coats. It's expected to be cold everywhere. We've tapered the rain chances leading into Christmas Eve and Christmas Day as it now appears most of the moisture will be pushed out of here leaving behind lots of clouds and cold conditions.
Look for high temperatures to be restricted to the mid and upper 40s Christmas Eve, Christmas Day and the day after before a slow warm up begins on Wednesday.
Models tend to struggle with arctic airmasses so it wouldn't surprise me, or the KHOU weather team, if it was a bit colder than currently forecast.
Overnight lows will likely drop below freezing (upper 20s and lower 30s) for the majority of the area Christmas night and the following night as well. So definitely have a place for the pets ready to go and cover the tender vegetation.
Despite some interesting computer model runs as of late, showing extreme, transcendent cold pouring into the nation around Christmas, there's too much model inconsistencies to touch too much on this possibility. More on that towards the bottom of this article as well.
Travel Weather Nation Wide
This will be a no-brainer: bring the heavy jackets -- especially if you're headed north into the Great Plains, Great Lakes or the northeast.
Very cold weather will dominate the country through the Christmas holiday with temperatures well below average for highs and lows.
Above is the raw model output for the morning of Saturday, December 23rd:
If you're planning on heading to Grandma's house this Saturday, a big storm system may cause delays in Chicago and Detroit, Nashville, Pittsburgh and much of the northeast corridor. The days before and after the 23rd look quiet and great for traveling through Christmas Eve.
Looking for a white Christmas?
A white Christmas is defined as having 1 inch of snow on the ground at 7 a.m. Christmas morning.
Right now it appears the best chance of seeing that will be in the Pacific Northwest, the Rockies and the northeastern corridor where they may see a fresh dusting of snow Christmas morning through the megalopolis of Washington, D.C., Baltimore, Philadelphia, New York and Boston as seen in the latest model above in the light blue shading.
A word about computer model storms and extremes
It's true that for many days the models were stirring up trouble over much of the state in the form of ice and snow leading into Christmas. I remember well -- I suffered from an extreme case of analysis paralysis watching every model run with acute focus.
The GFS (American Model) for over 30 runs in a row depicted a tremendous ice storm that would have paralyzed the state, as seen below in the model run from December 13th (six days ago as of this entry).
After 30 runs, time and time again, we began to mention the possibility of a disruptive storm near Christmas. But guess what? You live by the model, you die by the model. The model gaveth but it also tooketh away.
Looking at the models is certainly fun. They often paint appealing and flashy fantasies of what could happen; very much like the winter storm on Christmas across Texas, Houston included.
However there's a reason why we here at Channel 11 have to detain our emotions and sit on our hands when these superlative events are raging on the models; even though sometimes it requires a tranquilizer to keep me calm. In the back channels of the internet however, twitter, facebook and blog sites, etc, models and extremes are touched on and drooled over. But blogs and twitter posts aren't official forecasts. Therefore always be weary of posts online that show extended forecasts.
For example, this past weekend some of the models began showing a massive arctic high moving into the U.S. The highs were on the order of 1060 to 1070+ millibars in strength -- a lower 48 record if verified (seen above). High pressure cells that large indicate a devastating and deadly arctic outbreak, even for us in Houston. On Monday, the highs for the day after Christmas (over a week out) were showing up in the mid 20s! That hasn't happened here since the 80s and only a handful of times in the last 120 years. On Tuesday, the models snapped back to reality. They are now showing much more reasonable pressures and much more believable temperatures for Houston the day after Christmas (highs in the 40s vs 20s).
On the contrary, last weeks snow event in Houston was poorly forecast! In fact it wasn't clear it was going to snow in Houston until about 24 hours before it happened -- the exact opposite of what long range forecasts were showing.
As we have witnessed this go-around, the models change many, many times. They disagree with competing models and often disagree with themselves with each new run. Extreme events, whether it be a winter storm or blistering cold, they're extreme for a reason. They're several standard deviations below or above the mean. That means they don't happen often.
The winter is young and for those who are looking for another winter storm or looking for that hard freeze to kill the bugs, there is still plenty of time. The hardest freezes and the biggest snows have almost exclusively happened in February. Stay tuned.
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