A period of moderate to heavy snow developed over the north-central mountains of Colorado, with the highest amounts north of the I-70 Corridor. 5 inches near Winter Park.
Every event with a place to put it; 3 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 BOU wrote it up.
A period of moderate to heavy snow developed over the north-central mountains of Colorado, with the highest amounts north of the I-70 Corridor. Storm totals included: 27 inches, 1 mile north-northeast of Rabbit Ears Pass, 22.5 inches, 4 miles southeast of Mount Zirkel; 18 inches, 9 miles south-southeast of Spicer, 13.5 inches, 6 miles west of Arapahoe Peak; 12 inches near Climax, 5 miles west of Green Mountain Reservoir, and Loveland Pass; 10.5 inches near Copper Mountain, and 7.5 inches near Winter Park.
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 Denver/Boulder, CO wrote its last area forecast discussion before the first event at Feb 4, 3:37 AM MST, 7 hours 23 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 337 AM MST Thu Feb 4 2021 .SHORT TERM...(Today and tonight) Issued at 318 AM MST Thu Feb 4 2021 NW flow aloft will remain over the area today through tonight. Cross-sections show moisture depth in the mtns rather limited thru the aftn, however, orographics will remain favorable. Lapse rates are rather neutral, so any additional snow should be on the light side. Across nern CO, it will be dry with windy conditions late this morning thru the aftn hours. Could see gusts up to 40 mph. Highs across the plains will be in the mid 30s to lower 40s. For tonight, moisture will increase in NW flow aloft as the left front quadrant of an upper level jet moves into nrn CO. Combination of increased lift and favorable orographics should bring steady snow overnight, to the nrn mtns, with heavier snow possible in the Park Range after midnight. Thus will issue a warning for Zn 31 starting tonight. Elsewhere in the mtns winds will increase overnight as well with areas of blowing snow over the higher mtn passes with periods of light snow. May need a snow/blowing snow advisory for 33/34 for late tonight. Meanwhile cross-sections show some potential for a mtn wave overnight with cross barrier flow around 50 kts. Thus could see a few gusts from 60 to 70 mph in the foothills but will hold off on a high wind watch for now. Across nern CO it will be dry with decreasing winds. .LONG TERM...(Friday through Wednesday) Issued at 318 AM MST Thu Feb 4 2021 Strong northwest flow aloft is expected Friday into Saturday. An embedded shortwave trof moves across the state late Friday. This will result in strong winds in the mountains and areas of snow, especially on the western facing slopes. As the shortwave exits the state early Saturday, the atmosphere dries out with only a few mountain snow showers remaining Sunday. On the plains, less wind is expected overall with dry conditions and highs Friday in upper 30s to lower 40s, highs Saturday in the 40s, and highs Sunday in the 50s. Breezy conditions are expected near the Wyoming border and far northeast corner of the state. In addition, the Arctic airmass is lurking just off to the northeast of Colorado, so temperatures could be colder for the far northeast corner. The flow aloft becomes more westerly Sunday into Monday with a shortwave trof moving through northern Colorado on Monday. At the surface, a cold front moves through the eastern plains. We could see snow showers with the front or snow bands develop as the front moves through the northeast plains. Much like the snow band that developed Wednesday night south of the Denver metro area, could see some areas pick up a quick couple of inches, but hard to say where the band would set up. For now, have kept low pops in the forecast as moisture is again limited. The west northwest flow aloft continues Tuesday and Wednesday, with dry weather expected. Temperatures on the plains will be colder during this period with highs generally in the upper teens to around 30 which is colder than normal for this time of year, but still not as cold as our neighbors to the north and east. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 318 AM MST Thu Feb 4 2021 Winds may trend to light drainage by sunrise before switching to northwest by 18z with gusty winds thru the aftn. Winds should decrease by sunset and then go back to drainage by mid evening. Otherwise expect VFR today and tonight. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 8 AM MST this morning for COZ034. Winter Weather Advisory until 9 AM MST this morning for COZ031- 033. Winter Storm Warning from 5 PM this afternoon to 5 AM MST Saturday for COZ031. && SHORT TERM...RPK LONG TERM...Stark AVIATION...RPK
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 459 AM MST Thu Feb 4 2021 COZ030>051-051200- Jackson County Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- Grand and Summit Counties Below 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet- Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet- Central and Southeast Park County- Larimer County Below 6000 Feet/Northwest Weld County- Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County- North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Elbert/Central and East Douglas Counties Above 6000 Feet- Northeast Weld County-Central and South Weld County-Morgan County- Central and East Adams and Arapahoe Counties- North and Northeast Elbert County Below 6000 Feet/North Lincoln County- Southeast Elbert County Below 6000 Feet/South Lincoln County- Logan County-Washington County-Sedgwick County-Phillips County- 459 AM MST Thu Feb 4 2021 ...Winter Weather Advisories for northern Mountains until 9 am this morning... ...Winter Storm Warning for central Mountains until 8 am this morning... ...Winter Storm Warning for the Park Range tonight through Friday night... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Snow will decrease today in the mountains, however, some blowing snow will occur over the higher passes. Tonight, snow and wind will increase in the northern mountains, with heavy snow possible in the Park Range, after midnight. Wind gusts to 60 mph will produce blowing snow and poor visibility over the higher passes late tonight. Across the plains it will be colder and windy. Northwest winds will gust up to 40 mph at times this afternoon. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Snow, gusty winds and blowing snow will be possible in the mountains from Friday into Saturday. Travel may be difficult with slick roads and reduced visibility. A few snow showers will linger in the mountains Sunday along with gusty winds. On Monday, a cold front will bring a chance of snow and colder temperatures to the plains. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight but snowfall reports will be appreciated.
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
1006 AM MST THU FEB 4 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0958 AM SNOW FRISCO 39.59N 106.10W
02/04/2021 M5.5 INCH SUMMIT CO COCORAHS
CO-SU-4.
0954 AM HEAVY SNOW 7 NW SILVERTHORNE 39.73N 106.18W
02/04/2021 M6.5 INCH SUMMIT CO COCORAHS
CO-SU-8.
0937 AM SNOW DILLON 39.63N 106.04W
02/04/2021 M3.0 INCH SUMMIT CO CO-OP OBSERVER
DLLC2.
0940 AM SNOW ANTERO RESERVOIR 38.99N 105.89W
02/04/2021 M3.0 INCH PARK CO CO-OP OBSERVER
ANTC2.
0931 AM SNOW 1 SE GOULD 40.51N 106.01W
02/04/2021 M3.5 INCH JACKSON CO CO-OP OBSERVER
1000 AM SNOW 2 SSW ELKDALE 40.01N 105.89W
02/04/2021 M5.1 INCH GRAND CO COCORAHS
CO-GR-68.
0702 AM SNOW ELIZABETH 39.36N 104.60W
02/04/2021 M3.2 INCH ELBERT CO TRAINED SPOTTER
0650 AM SNOW 5 NE PONDEROSA PARK 39.47N 104.60W
02/04/2021 M1.7 INCH ELBERT CO TRAINED SPOTTER
E593.
0957 AM SNOW 5 SW CASTLE ROCK 39.33N 104.92W
02/04/2021 M5.9 INCH DOUGLAS CO COCORAHS
CO-DG-229.
0956 AM HEAVY SNOW 1 NNE PERRY PARK 39.28N 104.97W
02/04/2021 M6.0 INCH DOUGLAS CO COCORAHS
CO-DG-185.
0955 AM HEAVY SNOW 3 SE SHAMBALLA 39.34N 104.97W
02/04/2021 M6.3 INCH DOUGLAS CO COCORAHS
CO-DG-167.
1153 PM HEAVY SNOW PERRY PARK 39.26N 104.98W
02/03/2021 M9.0 INCH DOUGLAS CO PUBLIC
0948 AM SNOW 3 SSE SILVER PLUME 39.66N 105.71W
02/04/2021 M6.0 INCH CLEAR CREEK CO CO-OP OBSERVER
GCRC2.
1002 AM SNOW 1 ENE MEEKER PARK 40.23N 105.52W
02/04/2021 M5.0 INCH BOULDER CO COCORAHS
CO-BO-394.
0944 AM SNOW 1 WNW CRESCENT VILLAGE 39.94N 105.35W
02/04/2021 M3.0 INCH BOULDER CO TRAINED SPOTTER
LGRC2.
&&The national radar mosaic for the moment the first event began.
2 winter storm, 1 winter weather. Local standard time, as filed.
Storm totals up to 27 inches were observed.
Storm totals ranged from 12 to 18 inches.
Storm totals ranged from 7.5 to 13.5 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2021Every state in 2021This day in weather historyWarnings in Colorado, February 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: 942057, 942058, 942063.