Cold and moist air across western Colorado and eastern Utah combined with an upper level Pacific shortwave trough to produce widespread snowfall. The heaviest snow favored the mountains of southwest Colorado and southeast Utah.
Every event with a place to put it; 4 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 GJT wrote it up.
Cold and moist air across western Colorado and eastern Utah combined with an upper level Pacific shortwave trough to produce widespread snowfall. The heaviest snow favored the mountains of southwest Colorado and southeast Utah.
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 Grand Junction, CO wrote its last area forecast discussion before the first event at Dec 28, 3:48 PM MST, 12 hours 12 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 348 PM MST MON DEC 28 2009 .SHORT TERM...TONIGHT THROUGH WEDNESDAY... CLOUDS WERE INCREASING OVER THE SOUTH THIS AFTERNOON AHEAD OF A SPLIT TROF OVER THE WEST COAST. TEMPERATURES HAD WARMED IN THE UPPER VALLEYS AND LOWER SLOPES THIS AFTERNOON WHILE THE LOWERS VALLEYS LAGGED. THE PACIFIC TROF WILL MOVE ACROSS THE SOUTHWEST TONIGHT WITH MOISTURE SURGING NORTHWARD AHEAD OF IT. THIS WILL BRING INCREASED CLOUDS AND AREAS OF LIGHT SNOW TO THE ZONES SOUTH OF THE I-70 CORRIDOR LATE TONIGHT. SNOW WILL INCREASE IN AREAL COVERAGE TUESDAY WHILE SPREADING SLOWLY NORTHWARD DURING THE DAY. THE EVENT BEGINS WITH WEAK OVERRUNNING AND TRANSITIONS TO MORE OF POSITIVE VORTICITY ADVECTIVE/ OROGRAPHIC EVENT LATE IN THE DAY. THE TROF AXIS PASSES OVER THE REGION TUESDAY NIGHT WITH A DECREASE IN SNOWFALL. SYSTEM NOT VERY ENERGETIC...AS POINTED OUT IN THE PREVIOUS DISCUSSION...AND EXPECT SNOWFALL ACCUMULATIONS WILL BE RELATIVELY LIGHT (EG BELOW ADVISORY CRITERIA). HOWEVER...MODEL CONSISTENCY STRONGER THAN PREVIOUS RUNS... THEREFORE INCREASED POPS SIGNIFICANTLY. NEXT SHORTWAVE IN NORTHWEST FLOW ARRIVES WEDNESDAY BRINGING ANOTHER ROUND OF SNOWFALL TO THE AREA. TEMPERATURES WILL MODERATE BENEATH INCREASED CLOUD COVER BEGINNING TONIGHT. SYSTEMS NOT STRONG ENOUGH TO ERODE LOWER VALLEY INVERSIONS SO WILL CONTINUE TO UNDERCUT MOS FOR THOSE AREAS. .LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY... THE FLOW REMAINS PROGRESSIVE DURING THIS PERIOD AND DECENT CONSENSUS IS SEEN AT LEAST THROUGH THIS WORK WEEK. AS SUCH A HIGH PRESSURE RIDGE EXISTS ALONG 130W COMBINED WITH A DEEP POLAR VORTEX OVER HUDSON BAY. THIS WILL PROVIDE A NORTHWESTERLY FLOW ALOFT TO OUR CWA. AN EMBEDDED WAVE AND ITS ASSOCIATED COLD FRONT WILL PASS OVER THE REGION WEDNESDAY NIGHT. IT APPEARS ENOUGH FORCING AND MOISTURE WILL BE PRESENT FOR SUB-ADVISORY SNOW AMOUNTS OVER THE NRN AND CNTRL MTNS. THE RIDGE AXIS WILL THEN SHIFT EASTWARD THURSDAY AND DRIER MORE STABLE AIR WILL WORK INTO THE REGION. HOWEVER SCATTERED SHOWERS WILL LINGER OVER THE NRN MTNS. THE RIDGE BECOMES FLATTENED FRIDAY AS A PACIFIC SHORT WAVE MOVES THROUGH THE NRN ROCKIES. ENOUGH TRAILING ENERGY TO PRODUCE SCATTERED NRN MTN SHOWERS. RAISED POPS SOME TO REFLECT QPF TRENDS. THE NORTHWEST FLOW ALOFT IS EXPECTED TO PREVAIL SATURDAY THROUGH MONDAY AND MODEL CONSENSUS BEGINS TO STRAY SO CONFIDENCE DROPS. WITH THAT SAID THE GFS INDICATES NO SIGNIFICANT WINTER WEATHER... ALTHOUGH SCATTERED MOUNTAIN SNOW SHOWERS WILL CONTINUE MOST NOTABLY ACROSS THE NORTH. TEMPERATURES REMAIN PROBLEMATIC AND GUIDANCE SEEMS TO CONTINUE TO STRUGGLE WITH INVERSION TRAPPED VALLEYS. GENERALLY WENT SEVERAL DEGREES BELOW GUIDANCE ON BOTH MIN AND MAX READINGS IN THE VALLEYS. && .AVIATION... CLOUDS WILL BE INCREASING FROM THE SOUTH TONIGHT REDUCING FOG DENSITY ACROSS THE LOWER VALLEYS LATE TONIGHT AND TUESDAY MORNING. THESE AREAS STILL LIKELY TO SEE PERIODS OF MVFR VSBY AND/OR CIGS FROM MIDNIGHT THROUGH 17Z TUESDAY MORNING. MEANWHILE...SOUTH OF A KCNY- KGJT-KMTJ-KGUC LINE...LIGHT SNOW SHOWERS WILL DEVELOP PRODUCING MVFR CIGS AND VSBY...MAINLY OVER THE SAN JUAN...LA SAL AND ABAJO MOUNTAINS. SNOW WILL INCREASE AND SPREAD NORTHWARD DURING THE DAY FOR MORE WIDESPREAD MVFR CONDITIONS ALONG WITH LOCALIZED IFR CIGS AND VSBYS AT TIMES. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. SHORT TERM...NL LONG TERM....MC AVIATION.....NL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 545 AM MST MON DEC 28 2009 COZ001>014-017>023-UTZ022>025-027>029-291245- ANIMAS RIVER BASIN-ARCHES/GRAND FLAT-CANYONLANDS/NATURAL BRIDGES- CENTRAL COLORADO RIVER BASIN- CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN- CENTRAL YAMPA RIVER BASIN-DEBEQUE TO SILT CORRIDOR- EASTERN UINTA BASIN-EASTERN UINTA MOUNTAINS- ELKHEAD AND PARK MOUNTAINS-FLAT TOPS- FOUR CORNERS/UPPER DOLORES RIVER- GORE AND ELK MOUNTAINS/CENTRAL MOUNTAINS-GRAND AND BATTLEMENT MESAS- GRAND VALLEY-LA SAL AND ABAJO MOUNTAINS-LOWER YAMPA RIVER BASIN- NORTHWEST SAN JUAN MOUNTAINS-PARADOX VALLEY/LOWER DOLORES RIVER- ROAN AND TAVAPUTS PLATEAUS-SAN JUAN RIVER BASIN-SOUTHEAST UTAH- SOUTHWEST SAN JUAN MOUNTAINS-TAVAPUTS PLATEAU- UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE-UPPER GUNNISON RIVER VALLEY- UPPER YAMPA RIVER BASIN-WEST ELK AND SAWATCH MOUNTAINS- 545 AM MST MON DEC 28 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A CHANCE OF SNOW RETURNS TO THE MOUNTAINS TUESDAY WITH SNOW LIKELY ACROSS MOST MOUNTAIN RANGES WEDNESDAY AND WEDNESDAY NIGHT. SNOW WILL THEN CONTINUE OFF AND ON OVER THE NORTHERN MOUNTAINS THROUGH THE WEEKEND. .SPOTTER INFORMATION STATEMENT SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT. TGJT
The national radar mosaic for the moment the first event began.
3 winter weather, 1 winter storm. Local standard time, as filed.
Snowfall of 2 to 5 inches occurred across the area.
Snowfall of 2 to 4 inches occurred across the area.
Snowfall of 2 to 4 inches occurred across the area.
Heavy snowfall of 12 to 20 inches occurred across northern portions of the area, including the La Sal mountains. Southern portions of the area received 5 to 10 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2009Every state in 2009This day in weather historyWarnings in Utah, 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: 204927, 204928, 204926, 204929.