A long wave trough with several short waves moved across northern Arizona producing locally heavy snow.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS FGZ wrote it up.
A long wave trough with several short waves moved across northern Arizona producing locally heavy snow.
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 Flagstaff, AZ wrote its last area forecast discussion before the first event at Dec 27, 8:55 PM MST, 4 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 855 PM MST Mon Dec 27 2021 .SYNOPSIS...Rain and snow showers will continue to develop tonight and spread from west to east. Snow is expected as low as 4500 feet. Significant accumulations are possible above 5000-6000 feet. Windy conditions will continue across the area tonight and Tuesday, which could lead to areas of blowing snow. A second winter storm will move through the region Thursday into Saturday. && .DISCUSSION...A series of s/wvs moving through the mean trough over the western United States will bring a very active period to our CWA for the remainder of this week. The first s/wv is already through the area and was responsible for a windy afternoon, as well as cooling the atmospheric profiles a bit this evening. The second wave is now moving through southern Nevada with a decent area of cooling cloud tops developing out ahead of it. This wave will serve to increase shower activity across the area overnight, especially where upslope showers have already developed. A third wave, seen over the central Sierras, will move into our state Tuesday, with more noticeable cyclonic curvature compared to the first two waves. This will bring a more significant period of precipitation, roughly from Tuesday afternoon through Tuesday evening, lasting longest near the New Mexico border. Finally, a fourth wave moves down the west coast Wednesday and Thursday. This wave may cutoff and delay its arrival, or it may stay progressive and move through on Thursday. The cutoff scenario may also phase with a fifth and final wave dropping down from the north Friday, producing a significant snow event. Still a bit early to say on this one. With regard to winds, gradients have relaxed behind the s/wv from this afternoon, along with the usual diurnal decrease. Gradients will remain tight through Tuesday, but they have relaxed just enough to take down the Wind Advisories that were over the region. That does not mean there will still not be a few shower-driven and/or favored downslope region gusts that exceed 40 mph in the next 24 hours, just not enough areal coverage to justify a large Wind Advisory area. With regard to the current Winter Weather Advisories, they look reasonable. The product was updated to reflect current trends and address timing issues, but storm total amounts look good. Updates have been made periodically through the evening and no further updates are anticipated. && .AVIATION...For the 06Z package...A storm system will bring areas of MVFR/IFR conditions, spreading from west to east, in rain/snow showers tonight. LIFR to VLIFR conditions are possible over the higher terrain aft 18Z Tuesday in +SHSN and low CIGS. Winds remain gusty from the southwest, 15-25 kts with gusts up 40 kts across the high terrain/downwind of terrain. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...A storm system will bring persistent gusty southwest winds, snow down to 4500 feet, lower elevation rain, and continued cold temperatures through Tuesday night. Precipitation will become showery and decrease on Wednesday. Thursday through Saturday...Another storm system will bring more rain, snow, and wind Thursday and Friday. Precipitation will become showery on Saturday. Very cold temperatures are expected Saturday night. && .FGZ WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 PM MST Tuesday for AZZ007-008-015- 016-018. Winter Weather Advisory above 4500 feet from 5 AM to 11 PM MST Tuesday for AZZ037-038. Winter Weather Advisory from 11 AM to 8 PM MST Tuesday for AZZ039. Winter Weather Advisory from 11 AM Tuesday to 5 AM MST Wednesday for AZZ011. Winter Weather Advisory from 5 AM Tuesday to 5 AM MST Wednesday for AZZ017. Winter Weather Advisory above 4500 feet until 5 PM MST Tuesday for AZZ004-006. && PUBLIC...Peterson AVIATION...Peterson FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
The national radar mosaic for the moment the first event began.
2 heavy snow. Local standard time, as filed.
Heavy snow fell across the Western Mogollon Rim. Some reports include (in inches): Arizona Snowbowl (10,800 feet) 13.0, Flagstaff Airport 10.1, Parks 10.0, Kachina Village 9.0, Bellemont (NWS Flagstaff) 7.1, and Mormon Lake 7.0.
Forest Lakes reported 8 inches of snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2021Every state in 2021This day in weather historyWarnings in Arizona, December 2021
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 2026-09-24. Each event’s entry at NCEI: 998804, 998818.