A winter storm produced pockets of moderate to heavy snow for areas in and near the Front Range Foothills. U.
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 winter storm produced pockets of moderate to heavy snow for areas in and near the Front Range Foothills. Storm totals included: 10.5 inches, 6 miles south-southeast of Drake; 9.5 inches at the C.S.U. Campus in Fort Collins, 8 inches, 2 miles southwest of Golden and 3 miles southwest of Fort Collins; and 6.5 inches at Loveland.
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 Dec 5, 2:57 PM MST, 5 hours 3 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 257 PM MST SAT DEC 5 2009 .SHORT TERM...UPPER LEVEL TROUGH IS DROPPING SOUTH ACROSS THE NORTHERN ROCKIES AT THIS TIME. WINDS HAVE ALREADY SHIFT TO THE NORTHEAST IN RESPONSE TO A SURFACE LOW FORMING OVER SOUTHERN COLORADO. TEMPERATURES ARE IN THE MID 20S THROUGH SOUTHERN WYOMING SO IT WONT TAKE LONG FOR TEMPERATURES TO FALL. CLOUDS ARE INCREASING AND SOME LIGHT SNOW HAS DEVELOP OVER THE SOUTHERN HALF OF WYOMING. ITS APPEARING THINGS ARE COMING TOGETHER FOR SNOW TONIGHT AND SUNDAY. COLD AIR WILL CONTINUE TO FLOW INTO THE AREA TONIGHT. THE UPPER LEVEL LOW WILL MOVE SOUTH AND BE OVER NORTHERN UTAH COME 12Z SUNDAY MORNING. MODELS SHOWING GOOD QG LIFT OVER THE AREA FROM 06Z TO 18Z SUNDAY. THIS COMBINED UPSLOPE FLOW UP TO 700-750MB WILL CREATE WIDESPREAD SNOW TONIGHT AND SUNDAY. SNOW WILL BEGIN OVER THE MOUNTAINS THIS EVENING AND SPREAD EASTWARD OVERNIGHT. BY SUNDAY MORNING SNOW WILL BE WIDESPREAD OVER THE MOUNTAINS...FOOTHILLS AND OUT ACROSS THE EASTERN PLAINS. THE HEAVIEST SNOW AMOUNTS WILL BE IN THE FOOTHILLS AND IN THE MOUNTAINS EAST OF THE CONTINENTAL DIVIDE WHERE 6 TO 12 INCHES OF SNOW WILL BE POSSIBLE BY SUNDAY EVENING. FOR THE URBAN CORRIDOR...EXPECT 4 TO 8 INCHES WITH THE HIGHER AMOUNTS BEING NEAR THE FOOTHILLS AND LOWER AMOUNTS EAST OF I-25. FOR THE EASTERN PLAINS EXPECT 2 TO 4 INCHES OF SNOW. WIND DIRECTION IS POOR FOR OROGRAPHIC LIFT WEST OF THE DIVIDE AND ONLY EXPECT 2 TO 6 INCHES. HAVE ISSUED WINTER WEATHER ADVISORIES FOR THE MOUNTAINS...FOOTHILLS AND URBAN CORRIDOR FOR THIS SYSTEM. MAIN CONCERN WITH THIS SYSTEM WILL BE THE SNOW AND COLD. BECAUSE THE AIRMASS WILL BE SO COLD...ANY SNOW THAT FALLS WILL STICK TO THE ROADWAYS AND BECOME COMPACTED CREATING SLICK AND SLIPPERY ROADS. .LONG TERM...BROAD MID-LATITUDE TROUGH CARVING OUT OVER THE WESTERN CONUS EARLY IN THE EXTENDED PERIOD PROMISES TO KEEP TEMPERATURES BELOW IF NOT WELL BELOW AVERAGE AND KEEP SNOW CHANCES ON THE HIGH SIDE...PARTICULARLY OVER THE HIGHER TERRAIN. FLAT AXIS TROUGH WITH THE CENTER OF THE 500MB CLOSED LOW JUST OFF THE OREGON COAST SUNDAY NIGHT IS PROGGED TO OPEN UP AS IT ROTATES SEWRD OVER THE NRN GREAT BASIN MONDAY NIGHT AND TUESDAY. AS THE TROUGH SWINGS OUT OF THE PACIFIC NORTHWEST AND ITS AXIS BECOMES MORE VERTICALLY ORIENTED THE MEAN 700-500MB FLOW OVER COLORADO TRANSITIONS FROM A NEAR ZONAL FLOW TO A SWLY COMPONENT. STG JET FLOW ROUNDING THE BOTTOM OF THE TROUGH THEN MERGES WITH A SUBTROPICAL JET LADEN WITH SUBTROPICAL MOISTURE OVER THE DESERT SOUTHWEST. NAM AND GFS SHOW A LARGE AREA OF MODERATE/STRONG DEEP LAYER ASCENT OVER CALIFORNIA SUNDAY NIGHT AND EARLY MONDAY. MODELS SHOW THIS REGION OF VIGOROUS LIFT CONVERGING WITH THE DEEP MOISTURE STREAMING NEWRD OVER THE DESERT SOUTHWEST DURING THE DAY MONDAY/MONDAY NIGHT. THE TWO THEN SHIFT EAST OVER COLORADO ON TUESDAY. GFS LOOKS A BIT FASTER THAN OTHER MODELS WITH THIS SYSTEM. HPC FAVORS THE FASTER GFS. HOWEVER...MODELS HAVE TRENDED A TAD SLOWER EACH OF THE LAST COUPLE RUNS...POSSIBLY AN INDICATION THAT THIS SYSTEM MAY TURN OUT TO BE STRONGER THAN WHAT THE LATEST MODEL RUN INDICATES. AT ANY CASE...MODELS SHOW THE MEAN TROUGH AXIS POSITIONED JUST EAST OF COLORADO BY TUESDAY EVENING AND THE SWLY FLOW ALOFT BECOMING NWLY OVERNIGHT. ALL THIS POINTS TO A COLD...SNOWY AND WINDY PERIOD FOR THE NORTH- CENTRAL COLORADO MTNS AT LEAST THROUGH TUESDAY NIGHT. AT THIS TIME IT APPEARS SNOWFALL WILL DIMINISH IN THE HIGH COUNTRY SUNDAY NIGHT WITH WEAK SUBSIDENCE AND MID-LVL DRYING. SNOWFALL SHOULD THEN RAMP UP AGAIN MONDAY IN RESPONSE TO INCREASING OROGRAPHIC FORCING AND LARGE SCALE SYNOPTIC SCALE LIFT. SWLY FLOW NOT ALL THAT FAVORABLE FOR HVY SNOW PRODUCTION IN THE NRN MTNS...BUT AS THE TROUGH MOVES CLOSER...LARGE SCALE DYNAMICS SHOULD TRUMP THE LESS THAN FAVORABLE OROGRAPHICS. MTN AREA...ESPLY ALONG AND WEST OF THE CONTINENTAL DVD MAY SEE WARNING CRITERIA SNOWFALL LATE MONDAY THRU LATE ON TUESDAY. FOR LOWER ELEVATIONS...SNOW CHANCES NOT LOOKING ALL THAT GREAT DURING THE SAME THREE DAY PERIOD. THE SWLY FLOW ALOFT ALLUDED TO ABOVE ALSO LESS THAN FAVORABLE FOR AREAS EAST OF THE MTNS. MODELS INDICATE SELY BNDRY LAYER FLOW ON THE PLAINS MONDAY POOLING LOW-LEVEL MOISTURE UP ALONG THE CHEYENNE RIDGE. SLY/DOWNSLOPE FLOW OFF THE PALMER DIVIDE MAY ACTUALLY PRODUCE PARTIAL CLEARING OVER THE DENVER METRO AREA FOR A TIME ON MONDAY. BY NIGHTFALL...GFS SHOWS LOW LEVEL TURNING ELY IN RESPONSE TO FALLING PRESSURE/HEIGHTS OVER THE MTNS. WHILE THE NAM HANGS ONTO A RELATIVELY DRY S-SELY FLOW. WILL GO WITH A BLEND OF THE MODELS AND BEGIN RAMPING UP PRECIP CHANCES ON THE PLAINS...ESPLY UP ALONG THE FRONT RANGE. WILL GO WITH LIKELY POPS IN THIS AREA TUESDAY EVENING AND SCATTERED POPS FARTHER OUT ON THE PLAINS. BUT ITS ON TUESDAY WITH LOW LEVEL CYCLOGENESIS SOMEWHERE SERN COLORADO AND MODERATE QG ASCENT PASSING OVER THE AREA THAT CHANCES ARE GOOD THAT WE/LL SEE SOME ACCUMULATING SNOWFALL ON THE PLAINS. IT DOES NOT APPEAR TO BE A SIGNIFICANT SNOW EVENT...HOWEVER COULD SEE A FEW HRS OF MODERATE SNOWFALL WITH PASSAGE OF ANOTHER FAIRLY STG COLD FRONT LATE IN THE DAY. TEMPERATURE-WISE...DAYTIME READINGS LIKELY TO REMAIN WELL BELOW FREEZING PRETTY MUCH EVERYWHERE THRU TUESDAY NIGHT. THE COLD TEMPS MAY BE THE BIG NEWS MAKER FOR LOWER ELEVATION DURING THE FIRST HALF OF THE WEEK. MAX TEMP AT DENVER EXPECTED TO RUN SOME 25 TO 30 DEGS BELOW AVERAGE MONDAY AND TUESDAY. BY WEDNESDAY SHOULD SEE WARMING...BUT POSSIBLY NOT AS MUCH AS WAS EARLY THOUGHT. REST OF THE WEEK...AREAS EAST OF THE MTNS DRY OUT AND SLOWLY WARM UP..WHILE MTN AREAS MAY CONTINUE TO SEE PERIODS OF SNOW AND WIND AS THE GFS SHOWS YET ANOTHER U/A DISTURBANCE PASSING OVER THE AREA ON WEDNESDAY/ERLY THURSDAY AND W-NWLY UPSLOPE FLOW/CAA ADVECTION CONTINUING FOR THE REMAINDER OF THE WEEK. && .AVIATION...LOW CLOUDS WILL SPREAD SOUTH FROM WYOMING THIS EVENING WITH CEILINGS OF 2000-3000 FEET MOVING IN AROUND 02Z. SNOW WILL NOT BE FAR BEHIND AND DEVELOP AROUND 05Z. VISIBILITY AND CEILINGS WILL FALL THROUGH THE NIGHT. EXPECT VISIBILITY TO BOTTOM OUT AROUND A MILE AND CEILINGS TO LOWER TO 500-1000 FEET. CONDITIONS MAY IMPROVE SLIGHTLY SUNDAY AFTERNOON AS SNOW DECREASES. SNOWFALL AMOUNTS THROUGH SUNDAY AFTERNOON WILL BE 3-6 INCHES FOR KDEN...AND 4-8 INCHES FOR KAPA AND KBJC. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. MEIER/BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER CO 1108 AM MST SAT DEC 05 2009 COZ030>051-061300- 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- 1108 AM MST SAT DEC 05 2009 ...WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR PARTS OF THE AREA... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT SNOW WILL DEVELOP OVER THE MOUNTAINS THIS EVENING AND SPREAD EAST ACROSS THE PLAINS OVERNIGHT. SNOW ACCUMULATIONS THROUGH SATURDAY NIGHT WILL BE ONE TO THREE INCHES FOR MOST AREAS...WITH UP TO 6 INCHES IN THE FOOTHILLS AND OVER THE MOUNTAINS EAST OF THE CONTINENTAL DIVIDE. TEMPERATURES WILL COOL SHARPLY THIS EVENING WITH READINGS IN THE TEENS ON THE PLAINS AND SOME SINGLE DIGITS IN THE MOUNTAINS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SNOWFALL WILL CONTINUE DURING THE DAY SUNDAY WITH TEMPERATURES WELL BELOW AVERAGE FOR THE DATE. TOTAL SNOW ACCUMULATIONS BY SUNDAY EVENING WILL RANGE FROM 6 TO 12 INCHES IN THE FRONT RANGE FOOTHILLS AND MOUNTAIN AREAS ALONG AND EAST OF THE CONTINENTAL DIVIDE. SNOW TOTALS WITHIN THE I-25 URBAN CORRIDOR THE WILL RANGE FROM 4 TO 8 INCHES WITH THE HEAVIER AMOUNTS WEST OF I-25. AREAS FARTHER OUT ON THE PLAINS AS WELL AS MOUNTAIN AREAS WEST OF THE DIVIDE WILL SEE LIGHTER AMOUNTS WITH TOTALS RANGING FROM 2 TO 5 INCHES. MOST AREAS SHOULD SEE SNOWFALL DIMINISHING SUNDAY NIGHT...ONLY TO INCREASE AGAIN DURING THE DAY MONDAY AS ANOTHER PACIFIC STORM SYSTEM PASSES OVER THE REGION. SNOWFALL SHOULD COME TO AN END ON THE PLAINS BY WEDNESDAY BUT CONTINUE IN THE HIGH COUNTRY POSSIBLY THROUGH THE END OF THE WEEK. TEMPERATURES FOR THE FIRST PART OF THE WEEK WILL REMAIN WELL BELOW NORMAL...THEN GRADUALLY WARM DURING THE LATTER HALF OF THE WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. MEIER/BAKER
The national radar mosaic for the moment the first event began.
3 winter weather. Local standard time, as filed.
Storm totals included 10.5 inches, 6 miles south-southeast of Drake.
Storm totals included 8 inches, 2 miles southwest of Golden.
Storm totals included 9.5 inches at the C.S.U. Campus in Fort Collins, 8 inches, 3 miles southwest of Fort Collins and 6.5 inches at Loveland.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2009Every state in 2009This day in weather historyWarnings in Colorado, December 2009
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: 204284, 204285, 204286.