Another storm system brought more snow to the north-central mountains. Storm totals included: 10 inches at Copper Mountain Ski Area, 9 inches at Lake Eldora, 8 inches at Winter Park Ski Area, 7 inches at Breckenridge Ski Area and Rough and Tumble, with 6 inches at Bear Lake and Summit Ranch.
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 BOU wrote it up.
Another storm system brought more snow to the north-central mountains. Storm totals included: 10 inches at Copper Mountain Ski Area, 9 inches at Lake Eldora, 8 inches at Winter Park Ski Area, 7 inches at Breckenridge Ski Area and Rough and Tumble, with 6 inches at Bear Lake and Summit Ranch.
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 Apr 23, 2:47 AM MST, 8 hours 13 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 347 AM MDT SAT APR 23 2011 .SHORT TERM...SWLY FLOW ALOFT WILL BE OVER THE AREA THRU TONIGHT AS A COUPLE OF DISTURBANCES MOVE ACROSS. FIRST DISTURBANCE IS WELL DEFINED OVER SWRN UTAH AND SHOULD AFFECT THE MTN AREAS BY LATE MORNING OR EARLY AFTN WITH SOME INCREASE IN SNOWFALL MAINLY ALONG THE I-70 CORRIDOR. OVERALL OROGRAPHIC FLOW IS WEAK AND LAPSE RATES ARE NOT VERY IMPRESSIVE. IN ADDITION QG ASCENT IS RATHER WEAK AS WELL THUS MODELS COULD BE OVERESTIMATING PCPN AMOUNTS. EAST OF THE MTNS AIRMASS WILL BE VERY STABLE WITH LAPSE RATES IN THE 3-4 C/KM RANGE THUS EXPECT DRY CONDITION THRU AFTN EXCEPT CLOSER TO THE FOOTHILLS AND OVER THE PALMER DIVIDE WHERE A FEW SHOWERS MAY DVLP BY LATE AFTN. HIGHS THIS WILL BE COOLER WITH READINGS MAINLY IN THE LOWER 50S ACROSS NERN CO. FOR TONIGHT A SECOND WAVE IS SUPPOSED TO MOVE ACROSS THE RGN OVERNIGHT WITH LAPSE RATES SLIGHTLY MORE UNSTABLE HOWEVER OROGRAPHICS IN THE MTNS WILL STILL BE RATHER WEAK. COULD SEE ADVISORY NUMBERS OVER ZN 34 AND PARTS OF ZN 33. AT LOWER ELEVATIONS SFC HIGH PRESSURE WL WEAKEN AND MOVE EAST INTO THE CNTRL PLAINS AS SFC LOW PRES DVPS NR DENVER. THIS ALLOWS FOR ESE LOW LEVEL FLOW OVER MOST OF NERN CO EXCEPT NR THE FOOTHILLS WHERE FLOW BECOMES MORE ENE AND OVER THE PALMER DIVIDE WHERE A CONVERGENCE ZONE EXISTS. COULD SEE SOME CONVECTION DVLP ALONG THIS BNDRY BY EARLY EVENING OVER THE PALMER AND POSSIBLY IN THE NRN FOOTHILLS. MEANWHILE ADDITIONAL PCPN IS SUPPOSED TO DVLP ACROSS THE URBAN CORRIDOR BY AROUND 06Z AS 2ND WAVE MOVES ACROSS AND THEN SPREAD NE ACROSS THE PLAINS BY 12Z. SOUNDINGS SHOW WET BULB ZEROS LOWERING TO BLO 6000 FT BY MIDNIGHT WITH RAIN MIXING WITH OR CHANGING TO SNOW BEFORE DECREASING BY 12Z. COULD SEE AN INCH OR TWO ON GRASSY AREAS DEPENDING ON HOW QUICKLY PCPN CHANGES TO SNOW. .LONG TERM...LATEST INDICATIONS SHOW THAT Q-G LIFT ASSOCIATED WITH THE 2ND SHORT WAVE MENTIONED ABOVE WILL BE EXITING THE AREA BY EARLY SUNDAY MORNING. AS A RESULT...MOST RAIN/SNOW SHOWERS SHOULD HAVE MOVED EAST OF THE FRONT RANGE METRO AREAS AND INTO THE FAR NORTHEAST CORNER OF THE STATE. STILL CANT TOTALLY RULE OUT A FEW LIGHT SHOWERS LINGERING DUE TO THE NEARLY NEUTRAL MID LEVEL LAPSE RATES AND A HINT OF Q-G LIFT...SO WILL KEEP A SLIGHT CHANCE OF RAIN/SNOW SHOWERS IN THE EASTER MORNING FORECAST FOR NOW. BY AFTERNOON... AIRMASS WILL DESTABILIZE AGAIN WITH DAYTIME HEATING AND MORE INSTABILITY AS SHOWN IN THE FORECAST SOUNDINGS. IN ADDITION...THERE IS ANOTHER WAVE OF Q-G LIFT REACHING THE FORECAST AREA BY AFTERNOON WHICH WILL FURTHER AID SHOWER DEVELOPMENT. AIRMASS IS UNSTABLE ENOUGH TO WARRANT ISOLATED THUNDERSTORMS IN THE FORECAST AT LEAST IN THE MOUNTAINS...AND MAY HAVE TO ADD THUNDER IN THE LOWER ELEVATIONS DEPENDING ON SPEED OF APPROACHING SHORT WAVE. RIGHT NOW...THE BEST LIFT HOLDS OFF UNTIL SUNDAY EVENING...SO WENT AHEAD AND INCREASED POPS INTO THE LIKELY CATEGORY FOR THE ENTIRE FORECAST AREA AT THAT TIME. TEMPERATURES ARE COLD ENOUGH TO WARRANT ALL SNOW IN THE MOUNTAINS AND A MIX OF RAIN/SNOW IN THE FOOTHILLS AND MOUNTAIN VALLEYS BELOW ABOUT 9000 FEET. ON THE PLAINS...TEMPERATURES ARE JUST A COUPLE DEGREES WARMER TO KEEP PRECIPITATION MOSTLY IN THE FORM OF RAIN...ALTHOUGH CANT RULE OUT A LITTLE SLUSHY SNOW LATE SUNDAY NIGHT. HOWEVER...LATEST MODEL RUNS SHOW WET BULB ZERO LEVELS ONLY DROPPING TO AROUND 7000 FEET WHICH WOULD KEEP PRECIPITATION ALL RAIN. MODELS ARE STILL CONSISTENT IN SHOWING SUBSIDENCE AND DOWNSLOPING ACROSS THE FRONT RANGE BY MONDAY...BUT STILL ENOUGH INSTABILITY PRESENT TO KEEP ISOLATED SHOWERS IN THE FORECAST THROUGH MONDAY EVENING. IN THE MOUNTAINS...SNOW SHOWERS SHOULD CONTINUE WITH SOME OROGRAPHIC HELP. BY LATE MONDAY NIGHT INTO TUESDAY...A STRONGER WEST/NORTHWEST FLOW ALOFT WILL DEVELOP ACROSS COLORADO AS A STRONG 150 KNOT JET NOSES INTO NEVADA AND UTAH. THIS WILL HELP OROGRAPHIC FLOW INTO THE MOUNTAINS AND ALSO IMPROVE SYNOPTIC SCALE Q-G LIFT. COLD ADVECTION WILL ALSO BE UNDERWAY...ANOTHER FAVORABLE FACTOR FOR MORE SNOW IN THE HIGH COUNTRY WHEN AN ADVISORY MAY BE REQUIRED. ON THE PLAINS...INSTABILITY AND THE INCREASING LIFT FROM APPROACHING SHORT WAVE SHOULD ALSO IMPROVE THE ODDS OF SHOWERS...SO WENT ABOVE CLIMATOLOGY POPS FOR THIS PERIOD. MODELS ARE IN REASONABLE AGREEMENT FOR WEDNESDAY AND WEDNESDAY NIGHT WITH RIDGING...DRYING...AND WARMING. NEXT SYSTEM MAY BEGIN TO IMPACT THE NORTHERN MOUNTAINS BY LATE THURSDAY/THURSDAY NIGHT...WITH A SLIGHT CHANCE OF SHOWERS SPREADING ONTO THE PLAINS BY FRIDAY. && .AVIATION...WEAK UPSLOPE HAS ALLOWED CEILINGS IN THE 5000 FT RANGE TO DVLP EARLY THIS MORNING WITH SOME VIRGA AROUND. BNDRY LAYER IS STILL VERY DRY SO COULD SEE A SPRINKLE OR FLURRY EARLY THIS MORNING. SOUNDINGS FOR THIS AFTN SHOW AIRMASS PRETTY STABLE SO WL ONLY MENTION A SLIGHT CHC OF -SHRA. WINDS EARLY THIS MORNING WILL BE ENE AND THEN BECOME MORE ESE BY LATE MORNING AND THEN SELY BY 20Z. HRRR SHOWS WINDS BECOMING GUSTY SLY BY 21Z AS A SFC LOW WINDS UP NR THE AIRPORT WHILE THE NAM AND GFS KEEP WINDS SELY THRU 00Z. FOR NOW WILL GO WITH THE NAM AND GFS. FOR TONIGHT SHOULD SEE AN INCREASE IN SHOWER ACTIVITY AFTER 03Z WITH RAIN MIXING WITH OR CHANGING TO SNOW BY 06Z WITH MVFR CONDITIONS AND BRIEF IFR IN HEAVIER PCPN. COULD SEE LOCALLY UP TO AN INCH OF SNOW AT THIS AIRPORT HOWEVER WITH WRM GROUND TEMPS WOULD EXPECT RUNWAYS TO REMAIN WET. WINDS THIS EVENING COULD BRIEFLY BECOME MORE ENE DUE TO CIRCULATION NR THE AIRPORT BUT THEN SHIFT BACK TO MORE SELY AFT 06Z. IF WINDS REMAIN SELY OVERNIGHT WOULD THINK THIS WOULD LIMIT THE POTENTIAL FOR LIFR CONDITIONS SUN MORNING AS BEST CHC FOR FOG AND CEILINGS BLO 1000 FT WOULD STAY TO THE N AND NE OF THE AIRPORT. && .HYDROLOGY...NO HYDROLOGY ISSUES FOR THE FOURMILE BURN AREA TODAY OR TONIGHT AS RAINFALL RATES WILL STAY WELL BLO THRESHOLD CRITERIA. && .BOU WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY FROM NOON TODAY UNTIL 6 AM SUNDAY MORNING NRN MTNS...ZNS 33 AND 34. && RPK/BARJENBRUCH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER CO 1117 AM MDT SAT APR 23 2011 COZ030>051-241200- 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- 1117 AM MDT SAT APR 23 2011 ...SNOW ADVISORY FOR THE NORTHERN MOUNTAINS FROM NOON TODAY THROUGH 6 AM SUNDAY MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT SNOW SHOWERS WILL CONTNINUE IN THE MOUNTAINS THROUGH THIS AFTERNOON AND TONIGHT. ACCUMULATIONS OF 5 TO 10 INCHES WILL BE POSSIBLE. AT LOWER ELEVATIONS...AREAS OF RAIN OR SNOW WILL CONTINUE THROUGH TODAY...BUT WITH LITTLE ACCUMULATION. SHOWER ACTIVITY WILL INCREASE OVER THE PLAINS TONIGHT WITH ACCUMULATIONS OF 2 TO 5 INCHES IN THE FOOTHILLS AND AN INCH OR TWO POSSIBLE OVER THE URBAN CORRIDOR... MAINLY AFTER MIDNIGHT. OVER THE FAR NORTHEAST PLAINS THE BEST CHANCE FOR RAIN AND SNOW SHOWERS WILL BE AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY AN UNSETTLED WEATHER PATTERN WILL REMAIN OVER THE AREA THROUGH TUESDAY AS A SERIES OF WEATHER DISTURBANCES TO MOVE ACROSS COLORADO. EACH OF THESE DISTURBANCES WILL BRING A FEW INCHES OF SNOW TO THE MOUNTAINS...WITH RAIN SHOWERS OVER THE PLAINS. TEMPERATURES MAY BE COLD ENOUGH LATE SUNDAY NIGHT TO ALLOW A LITTLE SNOW TO MIX IN WITH THE RAIN ACROSS THE PLAINS. DRIER AND WARMER WEATHER IS EXPECTED TO DEVELOP BY THE MIDDLE PART OF NEXT WEEK. .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. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2011Every state in 2011This day in weather historyWarnings in Colorado, April 2011
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: 303210, 303211.