A strong upper level jet stream brought a prolonged period of moderate to heavy banded snow to portions of the North Central Mountains. with 6 to 12 inches elsewhere.
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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 strong upper level jet stream brought a prolonged period of moderate to heavy banded snow to portions of the North Central Mountains. Storm totals in the mountains of western Jackson and western Grand Counties ranged from 14 to 24 inches...with 6 to 12 inches elsewhere. Peak wind gusts to around 75 mph atop Berthoud and Loveland Passes produced blizzard conditions at times in the higher exposed areas. Several accidents, some serious, forced the closure of Interstate 70 west of Denver to Vail for several hours.
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 21, 3:15 PM MST, 4 hours 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 315 PM MST TUE FEB 21 2012 .SHORT TERM...THE NOSE OF THE STRONG NORTHERLY JET IS APPROACHING THE STATE THIS AFTERNOON AND WILL MOVE OVER THE FORECAST AREA LATER TONIGHT. THROUGH THIS AFTERNOON...THE WSR-88D HAS BEEN SHOWING SNOW RIGHT ALONG THE CONTINENTAL DIVIDE. HOWEVER...CROSS SECTIONS HAVE SHOWN A LAYER OF STABILITY OVER THE MOUNTAINS THAT HAS BEEN LIMITING SHOWER ACTIVITY ELSEWHERE IN THE HIGH COUNTRY. STABILITY ABOVE THE BOUNDARY LAYER IS FORECAST TO DIMINISH LATER THIS EVENING WHICH WILL ALLOW SNOW SHOWER ACTIVITY TO INCREASE OVER ZONES 31 AND 33. WITH ADDITIONAL SNOWFALL EXPECTED...WILL LET THE ADVISORY OVER ZONE 31 REMAIN IN PLACE. MODEL CROSS SECTIONS ALSO SHOW A MOUNTAIN-TOP STABLE LAYER REMAINING OVER THE SLOPES EAST OF THE CONTINENTAL DIVIDE WHICH WILL HELP PRODUCE THE AMPLIFIED MOUNTAIN WAVE WHICH WILL DRIVE THE ANTICIPATED CHINOOK HIGH WIND EVENT THROUGH THE NEXT 24 HOURS. CROSS SECTIONS AND PLAN VIEW WIND FIELDS INDICATE THAT THE STRONGEST WINDS SHOULD REMAIN IN THE FOOTHILLS. SINCE THE HIGH WIND WARNING IS ALREADY OUT FOR THE ADJACENT PLAINS...WILL LET IT CONTINUE...EVEN THOUGH CONFIDENCE IS LOW THAT STRONG WINDS WILL MAKE IT AS FAR EAST AS I-25. WINDS MAY EXTEND FURTHER EASTWARD TOMORROW AFTERNOON AS WARM TEMPERATURES ALLOW FOR GOOD MIXING OF THE BOUNDARY LAYER AND TRANSPORT OF THE JET STREAM ENERGY OVER A LARGER AREA. THE WARM TEMPERATURES ACROSS THE PLAINS WILL BE THE OTHER BIG STORY TOMORROW. GFS MOS GUIDANCE SEEMS TO BE OVERDOING THE WARMING...BUT THE NAM MOS GUIDANCE IS NOT WARM ENOUGH. WILL GO WITH AN AVERAGE OF THE TWO...EXCEPT FOR THE EASTERN ADAMS AND WASHINGTON COUNTY AREAS WHERE A SIGNIFICANT SNOWFIELD REMAINS IN PLACE. .LONG TERM...NORTHWESTERLY FLOW ALOFT WILL INCREASE WEDNESDAY NIGHT WITH A 110-130 KNOT JET MAXIMUM TO MOVE SOUTHWARD CROSS THE CWA THURSDAY MORNING. STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE CWA THROUGH THURSDAY EVENING...THEN A 100-120 KNOT JET MAXIMUM WILL MOVE EASTWARD ACROSS THE FORECAST AREA INTO FRIDAY AFTERNOON. THE REST OF FRIDAY AND FRIDAY NIGHT...THE FLOW ALOFT WILL DECREASE AND BECOME ZONAL BY 12Z SATURDAY MORNING WITH AN UPPER RIDGE MOVING IN. WEAK UPWARD SYNOPTIC SCALE ENERGY IS PROGGED OVER THE EASTERN HALF OF THE CWA WEDNESDAY EVENING...THEN DOWNWARD VERTICAL VELOCITY IS PROGGED THROUGH FRIDAY. THE BOUNDARY LAYER WIND PROGGS HAVE WESTERLY DOWNSLOPING WEDNESDAY EVENING. AFTER MIDNIGHT...STRONGER NORTHWESTERLIES KICK IN AND CONTINUE THROUGH THURSDAY NIGHT. THE LOW LEVEL GRADIENT RELAXES FRIDAY AND FRIDAY NIGHT...WITH NORMAL DIURNAL WIND PATTERNS EXPECTED. FOR MOISTURE... IT INCREASES WEDNESDAY NIGHT OVER ALL THE FORECAST AREA...ESPECIALLY IN THE MOUNTAINS. EARLY THURSDAY MORNING...THE EASTERN PLAINS MOISTEN UP PRETTY GOOD. THE MOUNTAINS HAVE PRETTY DEEP MOISTURE IN PLACE THURSDAY AND THURSDAY EVENING...THEN IT DECREASES. THERE IS SOME MID AND UPPER LEVEL MOISTURE OVER THE PLAINS THURSDAY AND THURSDAY NIGHT. FRIDAY IS PRETTY DRY...FRIDAY NIGHT IS VERY DRY. THE QPF FIELDS HAVE LIMITED MEASURABLE SNOWFALL OVER THE MOUNTAINS...WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THERE IS A TAD OF PRECIPITATION OVER THE PLAINS FROM 06Z TO 18Z THURSDAY...BUT IT IS VERY LIMITED. THERE IS NOTHING ON FRIDAY OR FRIDAY NIGHT. FOR POPS IN THE MOUNTAINS...WILL GO WITH 60-80% WEDNESDAY NIGHT THROUGH THURSDAY EVENING. MOISTURE AND OROGRAPHICS ARE GOOD...AND THERE IS SOME COLD AIR ADVECTION AS WELL. WILL DECREASE ALPINE POPS AFTER MIDNIGHT THURSDAY NIGHT...WITH NOTHING FRIDAY AND FRIDAY NIGHT. FOR THE PLAINS...WILL HAVE POPS IN THE FROM WEDNESDAY NIGHT MIDNIGHT THROUGH THURSDAY. THE BEST POPS WILL BE OVER THE EASTERN HALF WITH A BETTER POTENTIAL FOR UPSLOPE AND BETTER MOISTURE. THERE IS PRETTY FIERCE DOWNSLOPING OVER THE WESTERN PLAINS. THE PLAINS WILL BE DRY THURSDAY NIGHT THROUGH FRIDAY NIGHT. CONCERNING THE WIND THREAT...WILL KEEP HIGHLIGHTS AS IS FOR WINDS GOING WEDNESDAY NIGHT. THE MOUNTAIN WAVE SET-UP STILL LOOKS SIGNIFICANT. FOR TEMPERATURES...THURSDAY HIGHS ARE 7-12 C COLDER THAN WEDNESDAY'S HIGHS. FRIDAY'S READINGS ARE UP 1-2 C FROM THURSDAY. FOR THE LATER DAYS...SATURDAY THROUGH TUESDAY...MEDIUM RANGE MODELS HAVE AN UPPER RIDGE OVER COLORADO SATURDAY. BY SUNDAY...UPPER TROUGHING MOVES. THE ECMWF IS QUICKER WITH THIS THAN THE GFS. THE UPPER TROUGH STICKS AROUND THROUGH TUESDAY FOR THE MOST PART. RUN TO RUN MODEL CONSISTENCY WITH THIS FEATURE HAS NOT BEEN GREAT. MANY OF THE SPECIFICS...MOISTURE...TEMPERATURE...TO NAME A FEW ARE ALL OVER THE PLACE. IT SHOULD COOL DOWN FROM SATURDAY AND THERE SHOULD BE A "SLIGHT CHANCE" OR A "CHANCE" OF SNOW OVER ALL THE FORECAST AREA FROM SUNDAY THROUGH TUESDAY. && .AVIATION...CEILINGS AND VSBYS WILL REMAIN UNLIMITED THROUGH THE NEXT 24 HOURS...BUT WINDS ARE GOING TO PRESENT THE GREATER OPERATIONAL CHALLENGE. STRONG NORTHWEST FLOW ALOFT IS GOING TO CONTINUE THROUGH WEDNESDAY NIGHT WITH PERIODS OF GUSTY WINDS ALONG THE FOOTHILLS. PERIODS OF GUSTY WEST WINDS WILL EXTEND OUT TO KDEN AT TIMES THROUGH THE NEXT 24 HOURS. GUSTS TO 35 KNOTS OR MORE WILL BE POSSIBLE DURING WINDY PERIODS...ESPECIALLY BETWEEN 15Z AND 00Z ON WEDNESDAY. && .BOU WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM 11 PM THIS EVENING TO 5 AM MST THURSDAY FOR COZ033>036-038-039. WINTER WEATHER ADVISORY UNTIL NOON MST WEDNESDAY FOR COZ031. && SHORT TERM...KDRBY LONG TERM....RJK AVIATION...KDRBY
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER CO 1109 AM MST TUE FEB 21 2012 COZ030>051-221300- 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- 1109 AM MST TUE FEB 21 2012 ...HIGH WIND WARNING FRONT RANGE MOUNTAINS...FOOTHILLS...AND NEARBY PLAINS LATE TONIGHT THROUGH WEDNESDAY NIGHT... ...WINTER WEATHER ADVISORY NORTHERN GORE AND PARK RANGE THROUGH WEDNESDAY MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT GUSTY WEST WINDS WILL CONTINUE OVER THE HIGH MOUNTAIN PEAKS AND ALONG THE EASTERN SLOPES AND FOOTHILLS. AN UPPER LEVEL JET STREAM WILL MOVE OVER THE STATE TONIGHT...CAUSING PRESSURE GRADIENTS OVER NORTHEAST COLORADO TO STRENGTHEN. THIS WILL BRING EVEN STRONGER WINDS TO THE FOOTHILLS AND ADJACENT PLAINS. A HIGH WIND WARNING WILL BE IN EFFECT FOR POTENTIALLY DAMAGING WINDS TONIGHT. IN ADDITION TO STRONG WIND GUSTS...ROADWAYS NEAR OPEN FIELDS OF SNOW MAY BECOME SLICK BECAUSE OF BLOWING AND DRIFTING SNOW. MOISTURE MOVING INTO THE NORTHERN MOUNTAINS WILL CONTINUE PRODUCING SCATTERED SNOW SHOWERS IN THE COLORADO HIGH COUNTRY. ACCUMULATIONS IN THE NORTHERN GORE AND PARK RANGES MAY EXCEED 6 INCHES. OTHER MOUNTAIN RANGES WILL SEE LESSER AMOUNTS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY STRONG WINDS WILL OCCUR IN AND NEAR THE FRONT RANGE MOUNTAINS AND FOOTHILLS WEDNESDAY...WITH A GRADUAL RELAXING OF THE WINDS WEDNESDAY NIGHT. PEAK GUSTS APPROACHING 80 MPH CAN BE EXPECTED WEST OF I-25...WITH A FEW WIND PRONE AREAS IN THE FOOTHILLS SEEING WIND GUSTS NEAR 100 MPH. SNOW IS EXPECTED IN THE MOUNTAINS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...WITH SEVERAL INCHES OF ADDITIONAL SNOW ACCUMULATION LIKELY. THE PLAINS WILL SEE A CHANCE OF SNOW WEDNESDAY NIGHT LATE INTO EARLY THURSDAY EVENING. THE BEST CHANCE WILL BE OVER THE EASTERN HALF OF THE PLAINS. DRY WEATHER IS EXPECTED OVER THE FORECAST AREA FRIDAY THROUGH SATURDAY. THE NEXT STORM WILL MOVE INTO THE FORECAST AREA SATURDAY NIGHT...BRINGING A CHANCE OF SNOW INTO EARLY NEXT WEEK TO MOST AREAS. TEMPERATURES WILL BE BELOW SEASONAL NORMALS MUCH OF THE TIME...WITH SATURDAY BEING WARMER. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. DANKERS/RJK
The national radar mosaic for the moment the first event began.
2 winter weather, 1 winter storm. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2012Every state in 2012This day in weather historyWarnings in Colorado, February 2012
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: 365994, 365995, 365996.