Ice Storm Sunday into Monday?

Friday, December 12 -- 10:00AM

Greetings all! Here we are, back for another season of exciting Winter Weather events...

All weather sources point to a fairly significant Ice Storm threat to the STL region beginning Sunday night, and lasting into Monday mid-day. The National Weather Service (NWS) has been advertising this for the last couple of days.

Could it happen? Sure. The odds are in our favor. But before we break out the champagne, I am a little worried about a few of the details.

On the negative side:

• First off, this weekend is supposed to be mild, with temperatures in the upper 50s on Sunday afternoon. It would not shock me if we touch 60 due to the strong southerly winds predicted. This will thaw the ground to the point that it will take quite a bit of freezing precipitation to change the ground temperature.
• Second, with all of this warm air in place Sunday, I am a little worried about the accuracy of the Arctic air intrusion predicted by the models. Models commonly predict an Arctic "Express Train" of cold air, but in reality it usually turns out more to resemble the "Saint Louis Zoo train."
  
• Also, the timing of the onset of frozen precipitation has me concerned: the switchover from rain to freezing rain/sleet is not predicted to occur until after midnight early Monday morning.
• Forecast models have historically not done a good job predicting freezing rain/sleet events 3 days before onset, particularly in November/December.
  

On the positive side:

• That strong southerly flow Sunday will bring the necessary moisture to the Midwest for us. We won't have to overcome dry air before precip starts, as the air will already be saturated.
  
• My prediction that this will be a colder-than-average winter plays into our favor (take that, Global Warming)
  
• My prediction of a wetter-than-average also plays into our favor.

In the final analysis, I am not skeptical that we will get a lot of moisture, and therefore a lot of precipitation. I am just not yet convinced of the cold air intrusion. Three days out, it is simply too early to make that call.

But if you are interested in my prediction, stay tuned, and I will put out a prediction in the next 24-36 hours.

Keep your fingers crossed!

-WD