Weekend Weather Blog: A look back at a wild December

Wind chill explained
Published: Jan. 1, 2022 at 4:28 PM MST
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TWIN FALLS, Idaho (KMVT/KSVT) — If you took 2 snapshots of last month - one at the beginning of the month, and one at the end of the month - you’d think they’d be from different years. Record warmth and dryness at the beginning of the month left some worried that winter wasn’t going to come.

However, by the middle of the month, things changed in a big way. This started with a powerful system that brought over a foot of snow, some locales seeing over 2 feet, to much of the Wood River Valley. This very same system then brought powerful wind gusts to much of the Magic Valley and Snake River Plain.

Some locations saw wind gusts up to 70 miles an hour by the morning of December 14th. After the winds subsided, the first measurable snowfall was finally recorded in Twin Falls, with most locations in the Magic Valley seeing around an inch of wet, heavy snow. Another round of snow, dropping anywhere from 1-5″ (depending on where you’re located, came through on the 16th.

Then came winter’s stronghold. Beginning the morning of Christmas eve, multiple rounds of snow came through the entire area. Every day from the 24th to the 30th saw at least some snowfall, combining for over a foot of snow throughout the Magic Valley, up to 3 feet in the south hills, and just over 3 feet in the Wood River Valley.

Current Snow Depth (NOAA)
Current Snow Depth (NOAA)(Current Snow Depth (NOAA))

Above, we can see the official snow depth for the season this year. Most of the Magic Valley, thanks to some of the snowmelt, is currently seeing a snow depth anywhere between 4 and 10 inches, with localized areas seeing greater than 10. Further north into the Wood River Valley, most locations are seeing 20 to 40 inches, with localized areas seeing up to 60 inches.

Despite all of the snowfall in the middle and latter portions of the month, a tough start to the month kept much of the region below average for precipitation. Twin Falls saw 1.07″ of precipitation (liquid equivalent) for the month of December. This was .16″ below the normal of 1.23″. Jerome also fell just short of average, seeing 1.05″. This was .26″ below the normal of 1.31″.

Looking further east, however, above-average precipitation was experienced. Burley saw 1.15″ of precipitation, 0.09″ above the average of 1.06″. Interestingly enough, snowfall was a different story.

ID Central Plains Snow vs Precip Dec 21 (IEM)
ID Central Plains Snow vs Precip Dec 21 (IEM)(ID Central Plains Snow vs Precip Dec 21 (IEM))

Over the central Snake River Plain, December saw just under 20″ of snow (on average over the entire area). This is well above the 5.9 inch normal, and in fact, was the third snowiest December on record for the central plains climate division.

ID Central Mountains Climate Division Snow vs Precip (IEM)
ID Central Mountains Climate Division Snow vs Precip (IEM)(IEM)

Up north, we saw a much similar story. On average, over the Central Mountains climate division (covering a large area from Lewiston all the way to Bellevue), the region saw around 25 inches of snow for the month of December. This was still much above average and finished top 5 in all-time snowfall as well (number 4).

Temperatures, as everyone knows, were very up and down. The record warmth at the beginning of the month kept December’s average high above normal in Twin Falls, finishing at 41.7°. This was 4.8° above the normal of 36.9°. Jerome also finished warmer than normal, seeing an average high of 39.5°, 3.5° above the normal of 36°. Burley continued the above-average trend, finishing with an average high temperature of 42.5°, 5.2° above the average of 37.3°.

Overall, December was quite a month of ups and downs. With the La Nina in place, it’s looking like this up-and-down trend will continue into January.

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