A slow moving spring storm system produced significant snowfall across the mountains of northeast Utah.
Every event with a place to put it; 1 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 slow moving spring storm system produced significant snowfall across the mountains of northeast 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 May 21, 1:45 PM MST, 10 hours 15 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
245 PM MDT MON MAY 21 2007
.SHORT TERM (TONIGHT THROUGH TUESDAY)...
SURFACE FRONT AHEAD OF THE STRONG IDAHO TROUGH HAS MOMENTARILY
STALLED ACROSS NWRN UTAH. LIKE PREVIOUS DAYS...CONVECTION HAS FIRED
OVER THE HIGH TERRAIN OF WRN COLORADO...BUT DRIER AIR ADVECTING FROM
THE SOUTHWEST HAS STABILIZED THE AIR MASS TO SOME EXTENT AS
THUNDERSTORM COVERAGE HAS DECREASED DURING THE PAST HOUR. AS LONG
AS THERE IS SOME MID LEVEL MOISTURE...LOOK FOR ISOLATED TSTMS TO
PERSIST OVER WRN COLORADO MOUNTAINS THROUGH EARLY EVENING. GRADIENT
WINDS HAVE INCREASED AHEAD OF THE COOL FRONT ON THE ORDER OF 15 TO
20 KNOTS AND THIS WILL CONTINUE THROUGH THE EARLY EVENING HOURS.
NICE LOOKING RAIN BAND ON SALT LAKES RADAR AND APPEARS WRF AND GFS
MOISTURE FIELDS HAVE GOOD HANDLE ON THIS. BAROCLINIC BAND MOVES
ACROSS NE UTAH THIS EVENING...THEN SPREADS ACROSS NW COLORADO LATER
TONIGHT AND FINALLY REACHES SW COLORADO TUESDAY MORNING. QVECTORS
SHOW SOLID UPWARDS VERTICAL MOTION AND THAT THE PCPN SHIELD WILL BE
MORE DYNAMICALLY INDUCED RATHER THAN OROGRAPHICALLY ENHANCED.
BOOSTED POPS GRIDS LATE TONIGHT AND TUESDAY TO THE MODERATE TO
LIKELY RANGE WITH THE RAIN BAND...INCLUDING THE TYPICALLY DRIER
AREAS LIKE THE GRAND VALLEY. DRY SLOT FOLLOWS THE BAROCLINIC
BAND...BUT LOOK FOR SHALLOW CONVECTIVE SHOWERS TO FORM OVER THE NRN
HIGH TERRAIN IN THE AFTERNOON. TEMPERATURES WILL BE CONSIDERABLY
COOLER...PERHAPS AS MUCH AS 15 TO 20 DEGREES THANKS TO A RAIN COOLED
AIR MASS.
THE 700 MB 0C ISOTHERM DROPS SOUTHWARD NEAR THE COLORADO AND NEW
MEXICO BORDER. WITH A STABILIZING AIR MASS BUT COOL TROUGH AXIS
OVERHEAD...RADIATIONAL COOLING WILL BE MAXIMIZED WITH FREEZING
TEMPERATURES FOR THE HIGH VALLEYS ABOVE 6000 FEET. SPOTTY FREEZING
TEMPS MAY OCCUR IN THE LOWER VALLEYS AND THIS WILL NEED CLOSER
EXAMINATION FOR TUESDAYS FORECAST PACKAGE.
COLD TROUGH AXIS WILL BE OVER THE NRN AND CENTRAL PLAINS BUT BROAD
CYCLONIC FLOW COVERS MOST OF THE WRN CONUS. GRADIENT FLOW ACROSS
UTAH AND WRN COLORADO WILL BE RELATIVELY LIGHT...BUT STILL EXPECT
SOME SHALLOW SHORT LIVED OROGRAPHIC SHOWERS TO POP DURING THE
AFTERNOON.
.LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...
PRETTY QUIET WEATHER EXPECTED WED-THU AS THE FORECAST AREAS SHOULD
BE BETWEEN UPPER TROUGHS WITH WEAK SHORT TERN RIDGING. MARGINAL
INSTABILITY AND DAYTIME HEATING WILL KEEP A SLIGHT CHANCE OF SOME CO
MTN SHOWERS. THE NEXT TROF DEEPENS OVER THE GRT BASIN THURSDAY NIGHT
AND THEN SHOWS LITTLE EWRD PROGRESSION OTHER THAN SOME WEAK
EJECTING WAVES. AS SUCH SCT SHOWERS WILL PERSIST OVER THE MTNS MAINLY
NORTH OF I-70. NO SIGNIFICANT DIFFERENCES SEEN BETWEEN HPC GUIDANCE
AND GFS...ALTHOUGH HGHTS SLIGHTLY HIGHER WITH HPC MODEL. SOME
WEAK RIDGING SEEN LATE IN THE PERIOD AS THE NEXT TROF DEEPENS
ALONG THE WEST COAST. LITTLE CHANGE MADE TO THE CURRENT PRECIP GRIDS
AS A RESULT. TEMPS LIKELY TO REMAIN NEAR SEASONAL NORMS AND NOT
RETURN TO ABOVE NORMAL UNTIL RIDGE BUILDS IN SUN/MON.
&&
.AVIATION...WINDY CONDITIONS WITH GUST TO 30 KNOTS WILL OCCUR NORTH
OF LINE FROM KCNY TO KEGE. LESS GUSTY WINDS WILL OCCUR SOUTH OF THIS
LINE BUT STILL BREEZY WITH SUSTAINED WINDS OF 10 TO 15 KNOTS.
SCATTERED THUNDERSTORMS WILL EXIST OVER THE HIGH MOUNTAINS OF
WESTERN COLORADO WITH LOCALIZED OUTFLOW WINDS TO 35 KNOTS. COLD
FRONT REACHES KVEL AT 02Z...MOVES SOUTHEAST AND WILL BE ON A LINE
FROM KCNY-KGJT-KRIL-KEGE BETWEEN 06Z-09Z...AND KCEZ AND KDRO BETWEEN
12Z-15Z. SHOWERS AND ISOLATED THUNDERSTORMS CAN BE EXPECTED ALONG
AND BEHIND THE COLD FRONT FOR A FEW HOURS. VFR CONDITIONS WILL
PREVAIL TODAY THROUGH TUESDAY MORNING...HOWEVER MVFR CONDITIONS MAY
OCCUR WITH FRONTAL PASSAGE. EXPECT MOUNTAIN OBSCURATION WITH
SHOWERS.
&&
.FIRE WEATHER...
WINDS...MAINLY OVER THE NORTHERN HALF...HAVE BEEN INCREASING THIS
AFTERNOON AHEAD OF THE COLD FRONT THAT HAS BEEN APPROACHING FROM THE
NORTHWEST. ALSO HUMIDITY IS ON ITS WAY DOWN WITH KGJT AT 16% AT 200
PM MDT. HOWEVER HUMIDITY AT MOST SITES STILL ABOVE CRITERIA FOR THE
RED FLAG WARNING FOR ZONES 201 AND 203. BUT IT LOOKS LIKE A DRY SLOT
WILL ALLOW SKIES TO CLEAR FOR AN HOUR OR SO LATE THIS AFTERNOON INTO
EARLY THIS EVENING. AND DEWPOINTS ARE LOWER JUST WEST OF THE UT/CO
BORDER EARLY THIS AFTERNOON. SO EXPECT HUMIDITIES WILL CONTINUE TO
DROP AND STILL EXPECT THAT CRITERIA WILL BE MET ACROSS MUCH OF THE
ZONES COVERED.
AS THE FRONT PUSHES ACROSS THE FORECAST AREA SOUTHWEST WINDS WILL
INCREASE OVER THE SOUTH AHEAD OF THE FRONT...WITH NORTHWEST WINDS
DECREASING BEHIND IT. EXPECT WINDS TO REMAIN STRONG OVER THE SOUTH...
ESPECIALLY THE MOUNTAINS...THROUGH THE NIGHT. BUT THE STRONGEST
WINDS THERE WILL NOT COINCIDE WITH THE LOW DAYTIME RHS.
MUCH COOLER AIR WILL MOVE OVER THE ARE FROM THE NORTH BEHIND THE
FRONT...ENDING FIRE WEATHER CONCERNS FOR THE NEXT COUPLE DAYS.
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...RED FLAG WARNING FOR FIRE WEATHER ZONES 201 AND 203 BELOW 8000
FEET...NORTHWEST AND WEST CENTRAL COLORADO...UNTIL 8 PM MDT
THIS EVENING.
.UT...NONE.
PF/MC/EHHAZARDOUS WEATHER OUTLOOK...CORRECTED NATIONAL WEATHER SERVICE GRAND JUNCTION CO 611 AM MDT MON MAY 21 2007 COZ001>014-017>023-UTZ022>025-027>029-221145- 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- 611 AM MDT MON MAY 21 2007 ...RED FLAG WARNING FOR ELEVATIONS BELOW 8000 FEET IN WEST CENTRAL AND NORTHWEST COLORADO THIS AFTERNOON AND EARLY EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT BREEZY TO WINDY CONDITIONS WILL DEVELOP ACROSS THE AREA THIS MORNING AND CONTINUE THROUGH THIS EVENING AS A STRONG COLD FRONT MOVES INTO THE AREA. VERY DRY RELATIVE HUMIDITIES...COMBINED WITH SOUTHWEST WINDS FROM 15 TO 25 MPH WITH FREQUENT GUSTS TO NEAR 40 MPH WILL RESULT IN DANGEROUS FIRE WEATHER CONDITIONS ACROSS PORTIONS OF WESTERN COLORADO TODAY. AS A RESULT...RED FLAG WARNINGS HAVE BEEN ISSUED...PLEASE VISIT THE GRAND JUNCTION NATIONAL WEATHER SERVICE WEB SITE AT HTTP://WEATHER.GOV/GJT FOR MORE INFORMATION. IN ADDITION...ISOLATED THUNDERSTORMS WILL OCCUR OVER THE HIGHER ELEVATIONS THIS AFTERNOON WITH GUSTY WINDS TO 50 MPH AND BRIEF HEAVY RAINFALL EXPECTED. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS WILL SPREAD ACROSS THE REGION THIS EVENING AS THE COLD FRONT MOVES THROUGH. EXPECT FREQUENT LIGHTNING...STRONG WINDS AND LOCALLY HEAVY RAINFALL AS THE FRONT SWEEPS THROUGH. SHORTLY AFTER MIDNIGHT...SNOW IS EXPECTED TO DEVELOP OVER THE NORTHERN AND CENTRAL MOUNTAINS OF WESTERN COLORADO...WITH ACCUMULATIONS UP TO 4 INCHES POSSIBLE BY EARLY TUESDAY MORNING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY COOL...MOIST AND UNSTABLE CONDITIONS WILL BE IN PLACE ON TUESDAY WITH SCATTERED VALLEY RAIN SHOWERS AND MOUNTAIN SNOW SHOWERS. NO SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED FOR THE MOUNTAINS... ALTHOUGH MOUNTAIN HIGHWAYS WILL LIKELY BECOME ICY AND SNOWPACKED IN SPOTS. WARMER WEATHER MOVES IN ON WEDNESDAY AND CONTINUES THROUGH THE END OF THE WEEK...WITH A SLIGHT CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS EACH DAY...MAINLY OVER THE MOUNTAINS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY AND TONIGHT. JDC
The national radar mosaic for the moment the first event began.
1 winter weather. Local standard time, as filed.
Snowfall amounts of 5 to 7 inches occurred mainly along the north side of the eastern Uinta Mountains while 2 to 4 inches fell elsewhere.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2007Every state in 2007This day in weather historyWarnings in Utah, May 2007
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: 39214.