Friday Update: Arctic Cold is Coming, and Here to Stay Awhile

Temperatures to plummet
Overall things remain on track for a big change to our weather pattern next week. If you haven’t located your winter jacket (and let’s face it, we’ve hardly needed to), this weekend would be a good time to do so. Temperatures will be warm through the weekend, but then the bottom falls out.

Unlike most of our recent highly transient “cold” outbreaks, it appears as though this arctic blast will hang around awhile, and possibly a long while. Today’s 12z GFS has us dropping below freezing by Monday evening, and staying at or below freezing virtually through the end of the run (which is Sunday, Nov 23). Not only that, but it’s bringing multiple waves of reinforcing cold air to the region during this period. This is not to say this is a done deal, but other models have a very similar look. Here’s the 12z ECM deterministic which (rather dramatically) drops our temperatures Monday and keeps them below 32 degrees through the 17th.

WeatherBell Analytics

Take a look at these forecast 2 meter maximum temperatures for 12z next Thursday… COLD, with a good dose of below zero readings across Wyoming and Montana.

Weather5280 Models

With an unusually strong (for November) Arctic high overhead…

WeatherBell Analytics

The snow elephant in the room
The question we’re getting a lot, and rightfully so (we’re well overdue), is if, and how much, will it snow. The long and the short of it is, I’m still not all that impressed the snowfall outlook for next week, at least with the initial push of cold air. That being said, I do think there’s a good chance we at least see some snow by the second half of the day Monday, even if not a lot.

I’ll also add this: while these patterns aren’t typically big snow producers for us, they have a way of over performing every once and awhile. Couple that with high snow ratios (typically 20:1 to 30:1) with such cold temps, and the fact the GFS, EURO and Canadian all show multiple impulses over the extended period, it could be we come out of the freeze with more than just conversational flakes to ‘talk’ about.

There is still plenty of time to hash out the details around snowfall potential. For now, plan on a chance of snow by Monday and Monday night, and another chance already by the Wednesday/Thursday timeframe.

Be sure to check back in this weekend as you can bet there will be plenty to cover for this week’s State of the Atmosphere!

I’ll leave you with this cold and unsettled look from today’s 12z GFS run… #winter.

GFS Precip GIF

Brendan Heberton

Brendan is founder of Weather5280. He is co-founder of FreshyMap, and develops software for geospatial data analysis and visualization.

Denver, Colorado
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