A Pacific trough produced significant amounts of late season snowfall in some mountain areas of western Colorado.
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.
A Pacific trough produced significant amounts of late season snowfall in some mountain areas of western Colorado.
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 May 7, 3:39 AM MST, 6 hours 21 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 439 AM MDT MON MAY 7 2012 .SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT) ISSUED AT 431 AM MDT MON MAY 7 2012 SHRTWV ENERGY DIGGING SOUTHWEST ACROSS WYOMING AND NORTHERN UTAH WILL EVENTUALLY CLOSE OFF AS A DEEPENING LOW PRESSURE SYSTEM AS IT SAGS SOUTH INTO WESTERN ARIZONA TONIGHT. DEEP EASTERLY FLOW WILL HELP TO DRAG HIGH PLAINS MOISTURE WESTWARD ACROSS THE DIVIDE AND INTO WESTERN COLORADO TODAY. INCREASED INSTABILITY AS A RESULT OF COLDER AIR ALOFT MOVING OVER WILL RESULT IN INCREASED COVERAGE OF SHOWERS AND AFTERNOON THUNDERSTORMS TODAY. SOME SNOW EXPECTED ABOVE 9000 FEET...WITH THE INTERSTATE 70 IMPACTED NEAR VAIL PASS...ALONG WITH MONARCH PASS AND THE HIGHER PASSES THROUGH THE SAN JUANS. IMPACT ON HIGHWAYS EXPECTED TO BE NEGLIGIBLE AS A RESULT OF THE RECENT WARM WEATHER...SO NO WINTER HIGHLIGHTS PLANNED AT THIS TIME. CONVECTION ONGOING FROM THE AFTERNOON INSTABILITY LOOKS TO BE SUSTAINED INTO THE EVENING AND EARLY MORNING HOURS OVER THE SOUTHERN TWO-THIRDS OF THE CWA BY UPPER DYNAMICS. THIS UPPER SUPPORT WILL BE COMING FROM A DEFORMATION ZONE BEING PULLED THROUGH NORTHERN PORTIONS OF COLORADO AND UTAH BY THE MAIN UPPER LOW RETROGRADING SOUTHWARD THROUGH WESTERN ARIZONA. DRIER AIR MOVING IN BEHIND THE DEFORMATION ZONE SHOULD LEAD TO CLEARING SKIES ACROSS THE FAR NORTH. WITH CLOUDS IN PLACE MOST OTHER AREAS...LOWS WILL BE SLOW TO FALL AND THE CURRENT FORECAST LOOKS ON TRACK. TUESDAY THE DEFORMATION ZONE LOOKS TO STALL OVER THE SOUTHERN CWA AND MID LEVEL MIXING RATIO/S SUGGEST THE MOISTURE WILL BE TRAPPED OVER THE SOUTHERN CWA AS WELL. THIS MOISTURE SHOULD HELP INCREASE AFTERNOON INSTABILITY WITH MODELS STILL INDICATING LOW LEVEL CONVERGENCE ALONG THE SOUTHERN DIVIDE INTO THE WESTERN SAN JUANS SO CONFIDENCE STILL QUITE HIGH THAT THE LIKELY POPS STILL LOOK ON TRACK AND MADE VERY LITTLE CHANGES. TEMPERATURES WILL REBOUND ON TUESDAY AS CLOUD AND PRECIPITATION COVERAGE WILL BE REDUCED OVER THE REMAINDER OF THE CWA WITH THE BIGGEST CHANGE IN THE NORTHERN VALLEYS...WITH AFTERNOON READING PUSH BACK TO NEAR NORMAL. WITH THE UPPER SUPPORT WEAKENING THE CONVECTION SHOULD BE ABLE TO END OVER MOST OF THE AREA TUESDAY NIGHT AND HAVE REDUCED POPS ESPECIALLY AFTER MIDNIGHT. THE MODELS WANT TO KEEP THE CONVERGENT ZONE AND RESIDUAL MOISTURE IN PLACE ACROSS OUR SOUTHERN MOUNTAINS SO AGAIN HAVE ADDED AFTERNOON SHOWERS AND THUNDERSTORMS FROM THE CENTRAL DIVIDE INTO THE SAN JUAN RANGE BUT LEFT THEM LOW END SCATTERED TO ISOLATED. TEMPERATURES WILL CONTINUE THE TREND UPWARD AND HAVE SHOULD BE PUSH UP ANOTHER 5 DEGREES OR SO AS AN UPPER RIDGE OF HIGH PRESSURE IF NOSED INTO OUR CWA BY THE NEXT ARRIVING TROF AND PACIFIC JET TO THE NORTHWEST STATES. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 431 AM MDT MON MAY 7 2012 WESTERLY FLOW ALOFT STARTS OFF THIS PERIOD WITH A SUBTLE WAVE DROPPING INTO THE FORECAST AREA. THIS WILL KEEP UNSETTLED CONDITIONS OVER THE REGION AS SUFFICIENT MOISTURE REMAINS IN THE AREA TO KEEP SCATTERED CONVECTION GOING DURING THE AFTERNOON AND EVENING HOURS. THE WESTERLY COMPONENT TO THE FLOW LIFTS NORTH BY THE WEEKEND...WITH WESTERN RIDGE BECOMING MORE ESTABLISHED. HOWEVER...SOME ENERGY GETS TRAPPED UNDER THE BUILDING RIDGE WITH WEAKNESS NOTED OVER THE GREAT BASIN. MOISTURE POOLING ALONG THE FRONT RANGE WILL CONTINUE TO DRIFT WESTWARD THROUGH THIS PERIOD WITH DIURNALLY DRIVEN SHOWERS EXPECTED THROUGH THE WEEKEND. NO MAJOR QPF MAKERS EXPECTED AT THIS TIME...SO WILL KEEP POPS IN THE SCATTERED CATEGORIES AT BEST FOR NOW. TEMPERATURES WILL REMAIN ABOVE SEASONAL NORMS THROUGH THE PERIOD...IN SPITE OF THE INCREASED CLOUD COVER AND SHOWERS IN THE REGION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY NIGHT) ISSUED AT 431 AM MDT MON MAY 7 2012 VFR CONDITIONS EXPECTED TO CONTINUE AT ALL TAF SITES ACROSS WESTERN CO AND EASTERN UT THROUGH MID MORNING...WITH SHOWERS DEVELOPING OVER THE CONTINENTAL DIVIDE BY MIDDAY...DRIFTING WESTWARD THIS AFTERNOON. SOME MOUNTAIN OBSCUREMENT LIKELY TO OCCUR WITH SHOWERS AND LOWERING CLOUDS THIS AFTERNOON WITH THUNDERSTORM ACTIVITY INCREASING. MVFR CIGS POSSIBLE AT KASE AND KEGE FROM 16Z THROUGH 03Z THIS EVENING...WITH SHOWERS THEN DIMINISHING BY MIDNIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && SHORT TERM...JDC/15 LONG TERM...JDC AVIATION...JDC
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
The national radar mosaic for the moment the first event began.
4 winter weather. Local standard time, as filed.
Snowfall accumulations of 3 to 6 inches were measured above the 9000 foot level. Locally higher amounts included 8 inches on Schofield Pass.
Snowfall accumulations of 3 to 6 inches were measured above the 10,000 foot level.
Snowfall accumulations of 2 to 5 inches were measured above the 10,000 foot level.
Snowfall accumulations around an inch were measured across the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2012Every state in 2012This day in weather historyWarnings in Colorado, May 2012
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: 385000, 385003, 385004, 385002.