The snowpack continued to increase across the northern mountains. Storm totals included: 13 inches at Joe Wright, 12 inches at Elliot Ridge SNOTEL, 9 inches at Columbine SNOTEL, Long Draw Reservoir and Willow Park, with 8 inches at Arapahoe Basin, Deadman Hill and Never Summer.
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.
The snowpack continued to increase across the northern mountains. Storm totals included: 13 inches at Joe Wright, 12 inches at Elliot Ridge SNOTEL, 9 inches at Columbine SNOTEL, Long Draw Reservoir and Willow Park, with 8 inches at Arapahoe Basin, Deadman Hill and Never Summer. Lesser amounts of 4 to 7 inches were reported elsewhere.
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 29, 9:49 AM MST, 1 minute earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 1049 AM MDT FRI APR 29 2011 .UPDATE... && .SHORT TERM...FIRST WAVE OF SNOW IN THE MOUNTAINS CONTINUES TO INCREASE WITH A STRONG JET MOVING OVER THE AREA AND SO WE HAVE HOISTED A WINTER WEATHER ADVISORY FOR ZONES 31 AND 33 THROUGH 12Z SATURDAY. HAVE HELD OFF AT THIS TIME FOR ZONE 34 BUT MAY NEED TO ADD THAT WITH THE AFTERNOON FORECAST. THERE IS A PIECE OF THE APPROACHING TROUGH WITH ENHANCED LIFT NOW HEADING TOWARDS NORTHERN UTAH THAT SHOULD ENHANCE THE SNOW OVERNIGHT. ON THE PLAINS TEMPERATURES HAVE BEEN ADJUSTED TO SHOW THE COOLING ALREADY MOVING IN FROM NORTH TO SOUTH. .AVIATION...WELL DEFINED WIND SHIFT IS STILL APPROACHING DIA FROM THE NORTH BUT IT IS FAR FROM CERTAIN IT WILL MAKE IT WITH THE TIMING SHOWN IN THE TAF UPDATE. WILL CONTINUE TO WATCH CLOSELY FOR NAY ADDITIONAL UPDATES. && .PREV DISCUSSION... /ISSUED 822 AM MDT FRI APR 29 2011/ UPDATE... SHORT TERM...HAVE UPDATED THE GRIDS TO MOVE UP THE TIMING AND INCREASE POPS IN THE MTNS TODAY...ESPECIALLY IN ZONES 31 AND 33. ALSO ADJUSTED THE TEMPERATURES AND LOWERED THEM SLIGHTLY IN THE MOUNTAIN ZONES TODAY. PREV DISCUSSION... /ISSUED 405 AM MDT FRI APR 29 2011/ SHORT TERM...WARM TEMPERATURES ARE STILL EXPECTED TODAY AS WARM SOUTHWESTERLY FLOW WILL CONTINUE ACROSS THE STATE AHEAD OF AN APPROACHING UPPER TROUGH. HIGH TEMPERATURES IN THE LOWER 70S WILL BE QUITE COMMON ACROSS THE PLAINS. DURING THE AFTERNOON...THE WARM TEMPERATURES AND MODERATE TO STRONG WINDS ALOFT WILL COMBINE TO PRODUCE GUSTY SURFACE WINDS...ESPECIALLY ACROSS THE PALMER DIVIDE AND LINCOLN COUNTY. HIGH TEMPERATURES IN LINCOLN COUNTY WILL BE IN THE LOWER TO MID 70S WITH RELATIVE HUMIDITIES DROPPING TO THE MID TEENS. WINDS ARE ALSO EXPECTED TO BE 20 TO 25 MPH...JUST BELOW RED FLAG CRITERIA. WITH RECENT RAINFALL OVER THE PLAINS...FIELDS MIGHT BE GREEN ENOUGH TO LIMIT THE WILDFIRE DANGER THREAT SO NO FIRE WEATHER HIGHLIGHTS AT THIS TIME. BY LATE AFTERNOON...A SURFACE COLD FRONT SHOULD BE DROPPING OVER NORTHEAST COLORADO FROM THE NORTH. WINDS WILL BE SWITCHING TO THE NORTH...BUT IT WILL TAKE SEVERAL HOURS FOR THE AIRMASS TO MOISTEN AND PRODUCE MOSTLY CLOUDY CONDITIONS. IN THE MOUNTAINS...THE APPROACHING UPPER TROUGH SHOULD BEGIN PRODUCING SOME SNOW BY LATE THIS AFTERNOON. SNOW HAS ALREADY BEEN REPORTED IN ROCK SPRINGS WYOMING. THE UPPER TROUGH SHOULD MOVE OVER THE MOUNTAINS FAST ENOUGH TO KEEP NEW SNOW AMOUNTS BELOW ADVISORY CRITERIA. LATER TONIGHT...SHOWERS OF RAIN OR SNOW WILL BE POSSIBLE ACROSS THE PLAINS DUE TO THE UPSLOPE FLOW BEHIND THE COLD FRONT. MODEL SOUNDINGS SHOW A FAIRLY DEEP SATURATED LAYER OVER DENVER AT 09Z AND 12Z. WARM GROUND TEMPERATURES FROM THE PAST COUPLE DAYS OF WARM TEMPERATURES SHOULD KEEP ANY SNOWFALL FROM ACCUMULATING. LONG TERM...THE UPPER LEVEL TROUGH WILL SPLIT AS IT MOVES ACROSS THE AREA ON SAT AS ONE PIECE OF ENERGY MOVES INTO THE NRN AND CNTRL PLAINS WHILE THE OTHER PIECE OF ENERGY MOVES INTO SWRN COLORADO WHICH LEAVES NRN CO IN MAINLY WEAK NLY FLOW ALOFT. MEANWHILE SOME QG ASCENT WILL STILL AFFECT THE AREA SAT MORNING ALONG WITH SOME WK UPSLOPE FLOW MAINLY OVER THE SRN FOOTHILLS AND PALMER DIVIDE SO WILL KEEP BEST CHC FOR PCPN EARLY ON SAT IN THESE AREAS WITH ONLY A SLIGHT CHC ELSEWHERE OVER THE PLAINS. IN THE MTNS CROSS-SECTIONS STILL SHOW QUITE A BIT OF MOISTURE THRU THE AFTN WITH LAPSE RATES AROUND 8 C/KM SO SHOULD SEE CONVECTIVE TYPE SHOWERS. OROGRAPHICS WILL BE VERY WEAK SO AMOUNTS SO GENERALLY BE ON THE LIGHT SIDE. HIGHS ON SAT WILL BE MUCH COOLER AS 850-700 MB TEMPS DROP AROUND 15 DEGREES C SO WILL KEEP HIGHS MAINLY IN THE 45 TO 50 DEGREE RANGE OVER NERN CO. FOR SAT NIGHT BOTH THE NAM AND GFS SHOW ANOTHER SURGE OF COOLER AIR MOVING INTO NERN CO DURING THE EVENING WHICH BRIEFLY ENHANCES UPSLOPE FLOW IN AND NR THE FOOTHILLS. THE GFS GENERATES QUITE A BIT OF PCPN SAT EVENING WITH THIS FEATURE IN THE FOOTHILLS AND ACROSS THE PALMER DIVIDE WHILE THE NAM HAS VIRTUALLY NOTHING. THERE IS SOME MINOR QG ASCENT SAT NIGHT ALONG WITH FAIRLY DECENT LAPSE RATES SO WILL KEEP CHC POPS IN AND NR THE FOOTHILLS AND OVER THE PALMER DIVIDE FOR SAT NIGHT WITH ONLY A SLIGHT CHC OVER THE PLAINS. TEMPS WILL BE COLD ENOUGH FOR RAIN TO CHANGE TO SNOW ALONG THE URBAN CORRIDOR SAT EVENING BEFORE ENDING AROUND MIDNIGHT. IN THE MTNS THE BEST CHC OF PCPN SAT NIGHT WILL BE EAST OF THE DIVIDE WHERE UPSLOPE FLOW IS ENHANCED. ON SUN THE FLOW ALOFT WILL BE WEAK NELY AS THE UPPER LEVEL TROUGH WILL REMAIN OVER SWRN CO AS BEST QG ASCENT IS ACROSS SRN CO. LINGERING MOISTURE COMBINED WITH DECENT INSTABILITY WILL STILL ALLOW FORO A CHC OF SNOW SHOWERS IN THE MTNS. AT LOWER ELEVATIONS BOTH THE NAM AND GFS SHOW LOWER LEVELS WILL BE PRETTY DRY ON SUN HOWEVER WITH DECENT INSTABILITY AND MID LVL MOISTURE STILL COULD SEE A SLIGHT CHC OF SHOWERS DURING THE AFTN AND EARLY EVENING HOURS. MEANWHILE 850-700 MB TEMPS WILL ONLY RISE A DEGREE OR TWO SO AFTN HIGHS ACROSS NERN CO WILL STILL BE FROM 10-15 DEGREES BLO NORMAL. BY MON THE UPPER LEVEL TROUGH WILL SLOWLY MOVE SE INTO NRN NEW MEXICO WITH A DRIER AIRMASS DEVELOPING ACROSS THE AREA. HOWEVER ENOUGH MID LVL MOISTURE MAY LINGER FOR A LEAST A SLIGHT CH OF SNOW SHOWERS IN THE MTNS. OVER NERN CO WILL KEEP FCST DRY ALTHOUGH COULD SEE AN ISOLD AFTN SHOWERS NR THE FOOTHILLS AND OVER THE PALMER DIVIDE. HIGHS ON MON SHOULD BEGIN TO MODERATE SOME WITH READINGS RISING INTO THE 55 TO 60 DEGREE RANGE OVER NERN CO. BY TUE MAINLY DRY NW FLOW ALOFT WILL BE OVER THE AREA SO WILL NOT MENTION ANY PCPN. MEANWHILE A SFC LEE TROUGH WILL DEVELOP WITH DOWNSLOPE LOW LEVEL FLOW WHICH SHOULD ALLOW FOR HIGHS TO RISE BACK TO SEASONAL LEVELS ACROSS NERN CO WITH READINGS IN THE 60S. ON WED THE FLOW ALOFT WILL REMAIN NWLY WITH CROSS-SECTIONS NOT MUCH MOISTURE SO WILL KEEP FCST MAINLY DRY EXCEPT FOR A SLIGHT CHC OF SHOWERS IN THE MTNS. BOTH ECMWF AND GFS SHOW A WK FNT MOVING INTO NERN CO BY AFTN SO HIGHS ON WED MAY END UP A FEW DEGREES COOLER. FOR WED NIGHT INTO EARLY THU THE ECMWF SHOWS AN UPPER TROUGH AFFECTING NRN CO AS ANOTHER FNT MOVES ACROSS NERN CO WITH A CHC OF PCPN WHILE THE GFS HAS DRY NWLY FLOW ALOFT AND NO PCPN. THIS IS THE SECOND NIGHT IN A ROW BOTH MODELS HAVE SHOWN DIFFERENT SOLUTIONS SO WILL KEEP A SLIGHT CHC OF PCPN IN THE FCST UNTIL IT BECOMES MORE CLR WHICH WAY TO TREND. AVIATION...VISUAL LANDING CONDITIONS WILL PREVAIL THROUGH THIS EVENING WITH CEILINGS EXPECTED TO REMAIN ABOVE 10000 FT AGL THROUGH ABOUT 02Z. SOUTHERLY WINDS THIS MORNING WILL BECOME SOUTHWEST TO WESTERLY AND STRENGTHEN BY MIDDAY. A SFC COLD FRONT IS EXPECTED TO MOVE THROUH THIS EVENING WITH WINDS SWITCHING TO THE NORTH. THROUGH THE EVENING CEILINGS WILL GRADUALLY LOWER TO BELOW 6000 FT AGL BY 07Z WITH RAIN OR A MIX OF RAIN AND SNOW DEVELOPING BETWEEN 06Z AND 10Z. HYDROLOGY...LIGHT PRECIPITATION IS EXPECTED TO DEVELOP THIS EVENING AND OVERNIGHT. RAINFALL AMOUNTS SHOULD BE LIGHT WITH PRECIPITATION CHANGING OVER TO SNOW OVER THE FOURMILE BURN AREA BY MIDNIGHT. NO HYDROLOGY THREATS ARE EXPECTED. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 AM MDT SATURDAY FOR COZ031-033. && SHORT TERM...SZOKE LONG TERM....099 AVIATION...SZOKE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER CO 601 AM MDT FRI APR 29 2011 COZ030>051-291700- 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- 601 AM MDT FRI APR 29 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT WARM AND BREEZY CONDITIONS WILL PREVAIL ACROSS THE NORTHEAST COLORADO PLAINS TODAY...AHEAD OF AN APPROACHING WEATHER SYSTEM THAT WILL BRING CHANGES THAT WILL LAST THROUGH THE WEEKEND. HIGH TEMPERATURES ARE EXPECTED TO BE IN THE LOWER AND MID 70S ACROSS THE NORTHEAST COLORADO PLAINS TODAY...BUT GUSTY WINDS WILL ACCOMPANY THE WARM TEMPERATURES. SOUTHWEST WINDS UP TO 25 MPH CAN BE EXPECTED TO DEVELOP BY AFTERNOON...WITH AREAS ON THE PALMER DIVIDE AND ACROSS LINCOLN COUNTY EXPERIENCING GUSTS UP TO 40 MPH. THE FRONT RANGE FOOTHILLS AND HIGHER MOUNTAIN PEAKS WILL ALSO HAVE GUSTY WINDS TODAY. LATE THIS AFTERNOON...CONDITIONS WILL BEGIN TO CHANGE AS A COLD FRONT MOVES OVER THE NORTHEAST PLAINS. WINDS WILL SWITCH TO NORTHERLY AND TEMPERATURES WILL BECOME SHARPLY COLDER. OVERNIGHT THERE WILL BE A CHANCE OF RAIN OR SNOW AS UPSLOPE WINDS CONTINUE BEHIND THE FRONT. IN THE MOUNTAINS...AN UPPER LEVEL TROUGH WILL MOVE OVER THE STATE TONIGHT BRINGING SNOW TO THE HIGH COUNTRY. NEW SNOW ACCUMULATIONS UP TO 4 TO 8 INCHES WILL BE POSSIBLE FROM THIS AFTERNOON THROUGH TONIGHT. GUSTY WEST TO SOUTHWEST WINDS WILL ALSO OCCUR OVER THE HIGH COUNTRY...MAINLY THROUG THIS AFTERNOON. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY AN UPPER LEVEL TROUGH WILL LINGER OVER THE AREA FROM SATURDAY INTO SUNDAY WITH A COOL AN UNSETTLED PATTERN. SNOW SHOWERS WILL OCCUR BOTH DAYS IN THE MOUNTAINS WITH A CHANCE OF SNOW SHOWERS IN THE FOOTHILLS AND OVER THE PALMER DIVIDE. OVER NORTHEAST COLORADO THERE WILL BE A CHANCE OF SNOW SHOWERS SATURDAY MORNING MAINLY NEAR THE FOOTHILLS AND AGAIN SATURDAY EVENING AS ANOTHER SURGE OF COOLER AIR MOVES ACROSS THE PLAINS. FOR MONDAY AND TUESDAY A DRIER PATTERN WILL BE OVER THE AREA WITH A WARMING TREND. ANOTHER SYSTEM COULD AFFECT THE REGION BY THE MIDDLE OF THE WEEK AND BRING ANOTHER CHANCE OF PRECIPITATION TO THE AREA. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. DANKERS/RPK
The national radar mosaic for the moment the first event began.
3 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: 303213, 303214, 303215.