A storm system brought heavy snow to areas in and near the Front Range Foothillls. Multiple accidents occurred as the onset of the storm occurred during the evening commute.
Every event with a place to put it; 8 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 storm system brought heavy snow to areas in and near the Front Range Foothillls. Multiple accidents occurred as the onset of the storm occurred during the evening commute. A multi-car pileup occurred on eastbound I-70 which forced the closure of a four-mile stretch of the interstate in both directions from C-470 to Lookout Mountain. The Colorado State Patrol said at least 50 cars were involved, but not all crashed. Numerous vehicles became stuck when the slush turned to ice. About 60 flights were cancelled at Denver International Airport. Several cities from around Denver to Broomfield to Boulder were on accident alert.
Storm totals included: 18.5 inches at Eldorado Springs; 15 inches near Golden; 14.5 inches, 6 miles east of Nederland; 14 inches near Idledale and Jamestown; 13.5 inches near Pinecliffe; 12.5 inches, 12 miles northwest of Golden; 11 inches, 4 miles east-northeast of Conifer, the National Weather Service in Boulder and near Tiny Town; 10 inches at Gross Reservoir, Louisville; Ralston Reservoir, Stontia Springs Dam; 9.5 inches in Arvada; 9 inches near Lafayette; 8 inches near Erie, Westminster and Wheat Ridge. Elsewhere along the Urban Corridor, storm totals ranged from 3 to 7 inches.
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 25, 9:57 AM MST, 3 hours 3 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 957 AM MST WED FEB 25 2015 .UPDATE... ISSUED AT 945 AM MST WED FEB 25 2015 STRONG NORTHEAST WINDS ALREADY HAVE MOVED INTO DENVER A SHORT TIME AGO SO HAVE SPED UP THE TIMING BY 2-3 HOURS REGARDING THE ONSET OF PRECIPITATION. HIGHS LIKELY HAVE BEEN MET OR WILL BE MET SHORTLY THEN SHOULD SEE THEM DROP INTO THE 30S THIS AFTERNOON. STILL SOME QUESTION REGARDING THE AMOUNT OF SNOW FOR DENVER...THE ADVISORY MAY NEED TO BE UPGRADED CLOSER TO THE FOOTHILLS AND PALMER DIVIDE BUT STILL NOT SURE AT THIS TIME...WL SEE HOW THINGS DEVELOP THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH TONIGHT ) ISSUED AT 424 AM MST WED FEB 25 2015 A STREAK OF DIFFICULT FORECASTS REMAINS IN TACT. A LOT GOING ON THIS AFTERNOON AND EVENING...AND AGAIN POTENTIAL OF CONVECTION THROWS A LOT OF VARIABILITY INTO MODEL OUTPUT AND FORECAST CONFIDENCE FOR SNOWFALL AMOUNTS IN ANY PARTICULAR AREA. HERE IS WHERE WE ARE...LIGHT SNOW IS OCCURRING IN THE MOUNTAINS EARLY THIS MORNING BUT THIS SHOULD DECREASE AS SOME DRIER AIR ALOFT WORKS ACROSS THE AREA THIS MORNING. ON THE PLAINS...WE SHOULD SEE A FEW RAIN/SNOW SHOWERS SPREADING SOUTHEAST EARLY THIS MORNING...MAINLY EAST OF A GREELEY TO LIMON LINE. CANT EVEN RULE OUT A BIT OF FREEZING VERY LIGHT RAIN/SPRINKLES AS A FEW VALLEY LOCATIONS MAY HOVER JUST BELOW FREEZING AS LIGHT PRECIP BEGINS. CLOSER TO THE FRONT RANGE...OCCASIONAL GUSTY CHINOOK WINDS BUT WARM TEMPERATURES WILL REMAIN IN PLACE...AND ENOUGH DOWNSLOPE TO HAVE SOME BREAKS IN THE CLOUDS. MAIN FORECAST ATTENTION TURNS TOWARD STRONG COLD FRONT ACROSS THE PLAINS...WHICH IS ON TIME TO PUSH THROUGH BETWEEN 1 AND 3 PM. TEMPERATURES WILL DROP BEHIND THE FRONT WITH ANTICYCLONIC UPSLOPE DEEPENING. UPSTREAM MOISTURE SEEMS PLENTIFUL BASED ON REAL OBS AND PRECIPITATION OCCURRING TO OUR NORTH. LAPSE RATES BECOME MORE UNSTABLE...ESPECIALLY IN THE NAM WHERE SOME CAPE IS INDICATED...WHILE GFS IS SLIGHTLY MORE STABLE. THE NAM...AS WELL AS SEVERAL MESOSCALE MODELS INCLUDING THE NMM...ARW...AND THE FINAL HOURS OF THE RAP AND HRRR INDICATE CONVECTION BLOSSOMING WITH 2 INCH PER HOUR SNOW RATES. BUT THEY ALSO CONFINE THEM TO AREAS VERY CLOSE TO THE FOOTHILLS...WHICH SEEMS POSSIBLE CONSIDERING THE STRENGTH OF NORTH/NORTHEAST FLOW. IF THIS VERIFIES THEN HEAVIER SNOW WOULD CERTAINLY BE MORE FOCUSED TOWARD THE FOOTHILLS...AND MUCH LESS POTENTIAL FOR MUCH ACCUMULATION TOWARD FORT COLLINS...GREELEY...AND POINTS JUST EAST OF DENVER. WE HAVE TRENDED FORECASTS IN THIS DIRECTION SINCE THE STRONGER NORTHERLY FLOW USUALLY SHUTS THOSE AREAS DOWN PRETTY QUICKLY...AND DRIER LOW LEVEL AIR WITH COLDER ARCTIC AIR THIS EVENING WOULD HAVE A TENDENCY TO DO THE SAME. AT THE SAME TIME...THAT ALSO FOCUSES THE HEAVIER PRECIPITATION TOWARD THE FOOTHILLS SO HAVE OPTED TO ISSUE WINTER STORM WARNINGS FOR FOOTHILL LOCATIONS...MAINLY BOULDER COUNTY FOOTHILLS SOUTHWARD TO JEFFERSON/DOUGLAS COUNTIES. THE SOUTHERN FOOTHILLS HAVE NOT BEEN DOING VERY WELL WITH REGARD TO SNOW AMOUNTS IN THE PAST COUPLE STORMS BUT GIVEN THE STRONGER FLOW LATER TODAY WE DO EXPECT HEAVIER TOTALS THERE. ANOTHER CONCERNING AREA IF CONVECTION BLOSSOMS AS MESOSCALE MODELS INDICATE WOULD BE THE WESTERN SUBURBS FOR POTENTIAL WARNING CRITERIA. HARD TO EXACTLY SAY HOW THIS COMES TOGETHER BUT FOR NOW WILL ISSUE ADVISORIES STARTING AROUND 3 PM FOR THE DENVER/BOULDER METRO AREA AND PALMER DIVIDE. FORT COLLINS PER DISCUSSION ABOVE SEEMS TO GET EXCLUDED FROM HEAVIER PRECIPITATION AGAIN. SOME THREAT WESTERN SUBURBS COULD GET A QUICK 6 INCHES PLUS LATE THIS AFTERNOON/EVENING SO WILL MONITOR FOR POTENTIAL UPGRADE TO WARNING. OVERALL...THERE WILL BE A VERY LARGE DISPARITY WITH SNOW TOTALS WITH LITERALLY TRACE TO 10 INCH AMOUNTS POSSIBLE IN PORTIONS OF THE DENVER METRO AREA...AND HARD TO PINPOINT WHO GETS EXACTLY HOW MUCH. ONCE SNOW DEVELOPS WE DO ANTICIPATE RAPID DETERIORATION OF CONDITIONS AS SNOW INTENSITY COULD TURN DRY AND WARM ROADS INTO A QUICK SHEET OF PACKED SNOW/ICE. THE LATE AFTERNOON/EVENING COMMUTE FOR THE DENVER/BOULDER/PALMER DIVIDE/FOOTHILLS AREAS LOOKS DIFFICULT AT THIS POINT. FOR OVERNIGHT...SNOW INTENSITY IS EXPECTED TO GRADUALLY DECREASE WITH UPSLOPE COMPONENT WEAKENING AND AIRMASS STABILIZING WITH COLDER/DRIER BOUNDARY LAYER FLOW. MOST OF THE ACCUMULATING SNOW SHOULD BE OVER BY DAYBREAK SO WILL RUN WARNINGS AND ADVISORIES TIL 6 AM. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 424 AM MST WED FEB 25 2015 THE MEDIUM RANGE MODELS CONTINUE TO INDICATE THAT THIS EVENINGS SNOWFALL IS THE BEGINNING OF A PROLONGED PERIOD OF LIGHT SNOW ACROSS MUCH OF THE FORECAST AREA...ESPECIALLY THE MOUNTAINS. THE FLOW PATTERN ALOFT IS FORECAST TO BEGIN AS A CYCLONICALLY CURVED NORTHWESTERLY FLOW WITH A COUPLE EMBEDDED SHORT WAVE TROUGHS. BY FRIDAY EVENING...FLOW ALOFT ACROSS COLORADO WILL BECOME MORE WESTERLY AS AN UPPER TROUGH BEGINS CARVING OUT OVER THE PACIFIC NORTHWEST AND THEN GREAT BASIN. THE WESTERLY FLOW WILL BE MOIST WITH ENOUGH CYCLONIC CURVATURE TO MAINTAIN WEAK QUASI-GEOSTROPHIC FORCING FOR ASCENT ACROSS THE STATE. THIS WILL RESULT IN A CONTINUATION OF LIGHT SNOWFALL THROUGH FRIDAY AND SATURDAY. AT LOWER LEVELS...A VERY COLD AIRMASS WILL MOVE INTO THE REGION BEHIND THIS AFTERNOONS COLD FRONT AND TAKE UP RESIDENCE OVER NORTHEAST COLORADO THROUGH ABOUT SUNDAY. A LARGE SURFACE HIGH OVER THE CENTRAL PLAINS WILL MAINTAIN SOUTHEASTERLY LOW LEVEL FLOW ACROSS EASTERN COLORADO WELL INTO THE WEEKEND. THIS SHOULD CONTINUE FEEDING MOISTURE INTO THE REGION WHICH COULD BE HELD AGAINST THE FOOTHILLS BY A DENVER CYCLONE THAT WILL DEVELOP THURSDAY NIGHT AND LAST THROUGH SATURDAY. WITH WEAK DYNAMICS REMAINING OVERHEAD AND MOIST AIR AT LOWER LEVELS...LIGHT SNOW WILL BE POSSIBLE WHILE THE UPPER FLOW PATTERN REMAINS IN PLACE. BY LATE IN THE WEEKEND...THE UPPER TROUGH WILL SINK TO THE DESERT SOUTHWEST...LEAVING COLORADO UNDER THE DEFORMATION ZONE DOWNSTREAM OF THE UPPER CIRCULATION. THIS WILL PRODUCE THE HEAVIEST SNOWFALL MORE OVER SOUTHWESTERN COLORADO...SIMILAR TO WHAT OCCURRED THIS PAST MONDAY. BUT THE NORTH-CENTRAL COLORADO MOUNTAINS WILL BE ON THE NORTHERN FRINGES OF THIS SYSTEM AND SHOULD RECEIVE AT LEAST LIGHT SNOWFALL. NO FORECAST PERIOD IS EXPECTED TO CONTAIN PARTICULARLY HEAVY SNOWFALL AMOUNTS...BUT SEVERAL CONSECUTIVE PERIODS WITH 2 TO 4 INCHES OF NEW SNOW COULD ADD UP AFTER AWHILE. TEMPERATURE-WISE...THE COLDEST TEMPERATURES FOR NORTHEAST COLORADO WILL BE THURSDAY AND FRIDAY WITH ONLY SLIGHT MODERATION THROUGH THE WEEKEND. DURING THE FIRST HALF OF NEXT WEEK...THE GFS AND ECMWF HAVE SLIGHTLY DIFFERENT SCENARIOS INVOLVING THE WESTERN U.S. TROUGH MOVING ACROSS COLORADO. THIS WILL KEEP THE RATHER UNSETTLED WEATHER OVER THE STATE THROUGH THAT TIME. LITTLE WARMING CAN BE EXPECTED UNTIL AFTER THE MAIN TROUGH CLEARS THE AREA. ALL IN ALL...SNOWPACK CONDITIONS WILL ONLY IMPROVE THROUGH THE NEXT WEEK. && .AVIATION...(FOR THE TAFS THROUGH 18Z THURSDAY MORNING) ISSUED AT 945 AM MST WED FEB 25 2015 STRONG NORTHEAST WINDS ASSOCIATED WITH THE COLD FRONT ALREADY AT KDEN AND WILL BE AT KBJC AND KAPA. TIMING FOR THE ONSET OF PCPN WILL LIKELY MOVE UP AS WELL. VFR CONDITIONS THROUGH 18Z. WINDS NORTHEAST...WITH GUSTS AROUND 25 KNOTS EXPECTED. EXPECT ILS RESTRICTIONS BY 19Z WITH SOME MVFR CIG/VSBY RESTRICTIONS IN THE DEVELOPING SNOW SHOWERS. IFR CONDITIONS AND HEAVIER SNOW SHOWERS DEVELOPING 19Z-22Z WITH POTENTIAL FOR 1-2 INCH PER HOUR SNOW RATES AND TEMPO 1/4SM VISIBILITY 22Z-02Z. HIGHEST THREAT WOULD BE AT KBJC AND KAPA...BUT SOME THREAT AT KDEN TOO. OVERALL INTENSITY SHOULD DECREASE AFTER 04Z BUT IFR CONDITIONS WILL LIKELY LINGER WITH LIGHT SNOW THROUGH EARLY THURSDAY MORNING. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM MST THURSDAY FOR COZ039>041. WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 6 AM MST THURSDAY FOR COZ035-036. WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 6 AM MST THURSDAY FOR COZ033-034. && UPDATE...COOPER SHORT TERM...BARJENBRUCH LONG TERM...DANKERS AVIATION...COOPER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER/BOULDER CO 1022 AM MST WED FEB 25 2015 COZ030>051-261730- 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- 1022 AM MST WED FEB 25 2015 ...WINTER STORM WARNINGS FOR THE FRONT RANGE FOOTHILLS... ...WINTER WEATHER ADVISORY FOR DENVER METRO AREA...PALMER DIVIDE...AND MOUNTAINS THIS AFTERNOON AND TONIGHT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT CONDITIONS ARE EXPECTED TO CHANGE RAPIDLY THIS AFTERNOON FOLLOWING THE PASSAGE OF A STRONG COLD FRONT THAT HAS ALREADY MOVED INTO THE DENVER AREA. SNOW WILL LIKELY BECOME HEAVY AT TIMES IN AND RIGHT NEXT TO THE FOOTHILLS BY 1 TO 2 PM...STARTING FIRST IN THE NORTHERN FOOTHILLS AND THEN SPREADING ONTO THE NEARBY ADJACENT PLAINS. ONCE THE SNOW DEVELOPS...EXPECT A RAPID DETERIORATION IN TRAVEL CONDITIONS WHICH WILL LIKELY IMPACT THE AFTERNOON AND EVENING RUSH WITH SLOW AND HAZARDOUS TRAVEL CONDITIONS. DRY ROADS MAY RAPIDLY BECOME SNOWPACKED AND ICY IN THE HEAVIER SNOW AREAS. THERE MAY ALSO BE SIGNIFICANT VARIATIONS IN SNOWFALL AND ROAD CONDITIONS GIVEN THE LOCALIZED NATURE OF THE HEAVY SNOW SHOWERS ANTICIPATED THROUGH THIS EVENING. TOTAL SNOW ACCUMULATIONS OF 6 TO 12 INCHES IS EXPECTED FOR THE FOOTHILLS BY LATE TONIGHT...AND 3 TO 8 INCHES IN THE DENVER METRO AREA WITH THE HEAVIEST ACCUMULATIONS IN THE WESTERN SUBURBS AND SOUTH OF DENVER TOWARDS MONUMENT. FARTHER NORTH AND EAST TOWARD FORT COLLINS...GREELEY...AND LIMON ACCUMULATIONS WILL MOSTLY RANGE BETWEEN 1 AND 3 INCHES. SIGNIFICANT VARIATIONS ARE POSSIBLE...SO STAY TUNED FOR THE LATEST UPDATES. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY AREAS OF LIGHT SNOW WILL LINGER OVER THE MOUNTAINS...FOOTHILLS AND ADJACENT PLAINS ON THURSDAY WITH MUCH COLDER TEMPERATURES THAT WILL CONTINUE INTO FRIDAY. HIGH TEMPERATURES ON THE PLAINS MAY ONLY BE IN THE UPPER TEENS AND LOWER 20S THURSDAY AND FRIDAY WITH OVERNIGHT LOWS IN THE SINGLE DIGITS. ADDITIONAL SNOW ACCUMULATIONS ON THURSDAY OVER THE EASTERN PLAINS WILL BE LIGHT WITH HIGHER ACCUMULATIONS CLOSER TO THE FOOTHILLS. HIGHER MOUNTAINS AND FOOTHILLS COULD SEE ANYWHERE FROM 6 TO 8 INCHES BY THURSDAY EVENING WITH LOCALLY HIGHER AMOUNTS OVER THE HIGHER MOUNTAIN PASSES. LIGHT SNOW WILL CONTINUE IN THE MOUNTAINS THROUGH THE WEEKEND WITH A FEW INCHES OF ADDITIONAL ACCUMULATION EACH DAY. CONTINUED COLD TEMPERATURES AND A SLIGHT CHANCE OF SNOW WILL BE THE RULE ACROSS THE NORTHEAST COLORADO PLAINS AS WELL. EARLY NEXT WEEK...AN INCREASE IN SNOW TO THE MOUNTAINS IS POSSIBLE AS ANOTHER STORM SYSTEM MOVES IN. TEMPERATURES ON THE PLAINS WILL BE SLIGHTLY WARMER BUT WILL STILL BE COOLER THAN NORMAL FOR THE FIRST WEEK OF MARCH. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. HOWEVER...ANY REPORTS OF ACCUMULATING SNOWFALL WILL BE APPRECIATED.
The national radar mosaic for the moment the first event began.
5 winter weather, 3 heavy snow. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2015Every state in 2015This day in weather historyWarnings in Colorado, February 2015
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: 553366, 553367, 553369, 553370, 553371, 553372, 553373, 553368.