Wind gusts over 40 mph combined with a half inch to inch snowfall to cause whiteout conditions on Idaho Highway 32 between Tetonia and Ashton. The road closed at 1 pm MST on December 22nd.
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The episode as NWS PIH wrote it up.
Wind gusts over 40 mph combined with a half inch to inch snowfall to cause whiteout conditions on Idaho Highway 32 between Tetonia and Ashton. The road closed at 1 pm MST on December 22nd. The road re-opened later that evening.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Pocatello, ID wrote its last area forecast discussion before the first event at Dec 21, 1:40 PM MST, 23 hours 20 minutes earlier.
Area Forecast Discussion National Weather Service Pocatello ID 140 PM MST Mon Dec 21 2020 .SHORT TERM (Tonight - Thursday)... We've seen quite a bit of warming across the Magic Valley and lower Snake Plain with temperatures climbing into the 50s in Burley and Pocatello. Not everyone is seeing these warmer temps however as the Upper Snake Plain and eastern Highlands remain on the chillier side in the lower 40s. Southerly winds out ahead of an approaching front could allow for additional warming over the next few hours bringing daytime highs close to record values. These warmer temps will be very short- lived however as the aforementioned front will push through the region tomorrow bringing some light snow, gusty winds and much colder temperatures for the remainder of the week. Not much has changed with the forecast thinking for tomorrow, as hi- res models show the front nearing the Central Mountains during the overnight hours and bring it through the Snake Plain roughly around, perhaps just before, daybreak Tuesday. Best chance for light snow accumulations will be across the higher terrain of the central mountains and eastern Highlands where 1-4 inches will be possible. Highest totals will be across the highest terrain, while in the Snake Plain generally less than an inch. Most recent runs of the hi- res NAM and HRRR have been trending towards a more broken line of moderate snow as it nears the Snake Plain so it's possible our snow may be more scattered in nature as it moves through the Snake Plain. Regardless, snowfall rates might be in the 0.5-1" per/hr range over the short duration snow event. An additional concern will be the gusty winds associated with the frontal passage. Seems likely that wind advisory criteria will be met for about a 6-9 hr window tomorrow so went ahead and issued a wind advisory for much of the Snake Plain, eastern Magic Valley and Arco Desert given the likelihood of gusts in the 40-50 mph range. Given the gusty winds, blowing snow will be a concern as well, mainly across the higher terrain where more snow (and snowpack) will be present. Winds will gradually diminish by Tuesday night with colder air settling in over the region as we head towards the Christmas holiday. Our area looks dry, but cold, with highs below freezing Wednesday with lows in the single digits to well below zero in the normally colder spots. McKaughan .LONG TERM (Thursday through Monday)... Will have dry conditions under upper level ridge Thursday and Friday with temperatures near seasonal normals with generally good travel conditions expected Christmas Eve and Christmas day. A Pacific trof and associated cold front may return snow to the central mountains Friday night with a chance for widespread light snow on Saturday and Saturday night with light accumulations of 1 to 4 inches in the mountains and under an inch in the Snake Plain for early projections. Fairly low confidence on amounts right now. Models diverge Sunday and Monday with the European having a much wetter solution than the GFS which is dry. For now have light mainly eastern highland snow in for Sunday and Monday. Temperatures will be right around late December normal through the entire extended period with highs in the 20s mountains and upper 20s to mid 30s in the Snake Plain. GK && .AVIATION... Low ceilings continuing at DIJ this afternoon with MVFR at IDA occasionally. Should improve later this afternoon. Other sites maintain VFR conditions. Main impact will be very strong cold front moving through Idaho overnight and Tuesday morning. Should be a burst of snow with the front more prominently at SUN and DIJ and drop visibility to 3 miles at 11Z at SUN and to 2 miles at 14Z at DIJ. Kept visibility 4 miles or greater at BYi, PIH and IDA but increased wind speeds to sustained 25 to 35 knots at BYi, PIH and IDA by 14Z. Went with 15 to 20 knots at SUN and DIJ. GK && .PIH WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 5 AM to 5 PM MST Tuesday for IDZ051>055. &&
The national radar mosaic for the moment the first event began.
1 winter weather. Local standard time, as filed.
Wind gusts over 40 mph combined with a half inch to inch snowfall to cause whiteout conditions on Idaho Highway 32 between Tetonia and Ashton. The road closed at 1 pm MST on December 22nd. The road re-opened later that evening.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2020Every state in 2020This day in weather historyWarnings in Idaho, December 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 929723.