How The Rockies Protect The West From Arctic Outbreaks

I’m not a big beer drinker. However, I always have a few cans of Coors in my fridge in case some friends come over and want to crack a cold one. Why Coors? Because the mountains turn blue when it’s “as cold as the Rockies,” and since I have no stock in the taste, the cans and price are the only real factors in my purchasing decision. Laugh if you want, but it’s the honest truth!

Unfortunately, the folks at Coors don’t have a good understanding of the climatology of the Rockies – the mountains turn blue when the temperature reaches 46 degrees, which is far too mild for the Rockies. If I was head of marketing I’d brand the beer “as cold as the Appalachians” to ensure that we are referencing the correct climate zones in our advertising. Such a change would probably have disastrous effects on sales however, so it’s probably best that I’m not in marketing or sales.

Why am I talking about beer in a weather blog? We’ll see a massive pattern shift towards much cooler weather this week across the nation, but the truly frigid air will be kept at and east of the Continental Divide. The Rockies will experience their coldest temperatures of the year and will live up to Coors’ branding, however misleading it may be. But the Rockies will also prevent the coldest air from moving into the Columbia Basin or Intermountain West. There’s a reason why Coors doesn’t bill their beer as “cold as the Cascades!”


We saw a steady drip of light rain today as a weak, cool atmospheric river slowly pushed inland. Tuesday will feature mostly cloudy skies with showers as a cool upper-level trough slowly moves inland, with the heaviest showers occurring late Tuesday night/early Wednesday morning as the trough moves overhead. Snow levels should be in the 2,000 – 3,000 foot range and snow advisories are in effect for 8-16″ of snow over the Southern Washington/Northern Oregon Cascades from 10am Tuesday through 4am Wednesday, and there is even a slight chance of weak thundershowers along the coast where the atmosphere will be a bit more unstable.

Showers should end near or shortly after sunrise (7:29 am for Portland) Wednesday, and the rest of the week will be relatively pleasant as a weak ridge begins to build overhead. Expect patchy fog both Thursday and Friday mornings due to light winds aloft coupled with residual moisture at the surface, and mostly cloudy skies in the afternoon with just a few showers both days, primarily over Washington. By Saturday, this ridge will strengthen further and direct the storm track all the way north to the Alaskan Panhandle, giving us partly cloudy skies with highs rising into the low 50s.

Predicted 500mb height anomalies at 7am PST Sat 2/6 from the 12Z 2/1 ECMWF deterministic model. Note the ridge along the West Coast but deep trough and “polar vortex” over the Northern Plains
Credit: Weatherbell

But while this ridge will bring pleasant weather to the Pacific Northwest, it will also allow the dreaded “polar vortex” to slip south into the Upper Plains, bringing them the coldest temperatures of the season. Look at all those negative temperatures over Montana, Wyoming, and the Dakotas Saturday morning! And winds over the Northern Plains should be in the 15-25 mph range at this time, bringing windchills all the way to -30 to -45 or even less in the coldest/windiest spots!

Predicted 2-meter temps at 7am PST Sat 2/6 from the 12Z 2/1 ECMWF deterministic model
Credit: Weatherbell

Notice how the Rockies completely block this frigid air from moving into the Intermountain West. In the image above, Browning in Northwest Montana just to the east of the Rockies is sitting at -7 while Spokane, WA is at 31. Granted, Browning is about 2,500 feet higher than Spokane, but still, this illustrates how well the Rockies protect us from frigid, arctic air. Because arctic air is so dense, it is channeled by terrain and does not flow above it, so the Rockies simply direct this arctic air east. A topographical map of the US is below for reference – you can really see how the Rockies “guide” this cold, dense air eastward and prevent it from moving into the Intermountain West.

Topographic map of the US.
Credit: Joe Grim

And now, back to beer. Did the marketing department at Coors choose the coldest, most refreshing mountain range, or are there even colder mountains in the Lower 48? In my opinion, they got the right mountain range; the combination of high altitude and susceptibility to arctic outbreaks makes the Rockies a force to be reckoned with. But if you really want the most refreshing beer, just make sure you crack your cold one east of the crest, where the real arctic air lies.

Or, you could just go to the Appalachians, where the beer will be chilled and more importantly, in liquid form. 🙂

Have a great week,
Charlie

Featured image: Valley of the Ten Peaks and Moraine Lake, Banff National Park, Canada. Mountains from left to right: Tonsa (3057 m), Mount Perren (3051 m), Mount Allen (3310 m), Mount Tuzo (3246 m), Deltaform Mountain (3424 m), Neptuak Mountain (3233 m)Credit: Wikimedia user Gorgo

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