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Yes you're right, Montana is climatologically very weird due to the geography.
Averages in most cities there are quite lame compared to, say, ND or MN, but the extremes are still comparable or even colder. This is apparent by comparing, for instance, Billings to Fargo or Duluth. I would be willing to believe that the geography can create those extremes.
Elevation must play a part, too. Even if locally the averages aren't that cold, if an especially airmass moves in from the Great Plains, it wouldn't get Great Plains surface weather, it would get Great Plains temperatures at the 800-850 mb level. Of course, 850 mb temperatures don't go down to -70°F, additional radiational cooling in a frost hollow must help
Elevation must play a part, too. Even if locally the averages aren't that cold, if an especially airmass moves in from the Great Plains, it wouldn't get Great Plains surface weather, it would get Great Plains temperatures at the 800-850 mb level. Of course, 850 mb temperatures don't go down to -70°F, additional radiational cooling in a frost hollow must help
That's very true, it's pretty much the opposite of a Chinook. When a cold snap comes in from the east it tends to intensify because of the higher elevation. If you look at a lot of the coldest days in Front Range locations, the wind direction is usually NE/NNE/ENE.
That's very true, it's pretty much the opposite of a Chinook. When a cold snap comes in from the east it tends to intensify because of the higher elevation. If you look at a lot of the coldest days in Front Range locations, the wind direction is usually NE/NNE/ENE.
February 1996. That month reached 80 degrees and 0 degrees. a 80 degree temp range! talk about extreme. in Raleigh nc!
February 1996. That month reached 80 degrees and 0 degrees. a 80 degree temp range! talk about extreme. in Raleigh nc!
I thought we were talking about deviations from average lows, not monthly ranges.
If you want to talk about monthly range, I'm sure the title goes to Montana as well. Apparently Loma MT has had a 103F range within a single 24-hour period. A chinook in Jan 1972 rose the temp from -54 to 49F.
I thought we were talking about deviations from average lows, not monthly ranges.
If you want to talk about monthly range, I'm sure the title goes to Montana as well. Hell, Loma MT has had a 103F range within a single 24-hour period.
850 mb scale bottoms out at -28°C. There was a cold air mass centered around Manitoba.
(Well, if you believe Meteociel has accurate data 60 years back.) Looking at the 850mb temps that day, it looks like they were around -25C or even below at 12:00 (UTC). Now, the temps at 5600 ft in Rogers Pass should be slightly below the 850mb temp, so I find it somewhat plausible that a high of -22F was possible that day. Now, in order for the -70 to happen, undoubtedly the place where the gauge was located was in a frost hollow, and there needed to be really calm winds that allowed for an incredibly strong temp inversion. But still seems kind of unlikely. Then again, many extreme events do before they actually happen.
(Well, if you believe Meteociel has accurate data 60 years back.) Looking at the 850mb temps that day, it looks like they were around -25C or even below at 12:00 (UTC). Now, the temps at 5600 ft in Rogers Pass should be slightly below the 850mb temp, so I find it somewhat plausible that a high of -22F was possible that day. Now, in order for the -70 to happen, undoubtedly the place where the gauge was located was in a frost hollow, and there needed to be really calm winds that allowed for an incredibly strong temp inversion. But still seems kind of unlikely. Then again, many extreme events do before they actually happen.
Here's NCEP reanalysis of the same day, which is probably the source Meteociel is using. Plot shape is a bit easier to read:
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in Raleigh nc!
