Strong upper level winds in combination with a tight pressure gradient at the surface prompted a high wind warning for the Laramie Valley and Laramie Mountains due west of Cheyenne.
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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 CYS wrote it up.
Strong upper level winds in combination with a tight pressure gradient at the surface prompted a high wind warning for the Laramie Valley and Laramie Mountains due west of Cheyenne.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at May 22, 2:03 AM MST, 4 hours 57 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 303 AM MDT SAT MAY 22 2010 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT...CURRENT IR SATELLITE LOOP SHOWS MAINLY CLEAR SKIES ACROSS EXTREME SOUTHEAST WYOMING AND WRN NEBRASKA EARLY THIS MORNING WITH SOME SHOWER ACTIVITY AND AN EMBEDDED TSTORM OR TWO WEST OF I25 OVER CENTRAL WYOMING. THE STRONG TSTORMS FROM YESTERDAY HAVE PUSHED EAST...WHERE A STRONG LLVL JET HAS RESULTED IN A MCS OVER THE DAKOTAS EARLY THIS MORNING. EXPECT ISOLATED SHOWERS AND MAYBE A LIGHTNING STRIKE OR TWO OVER CARBON AND ALBANY COUNTY THIS MORNING...MAINLY DUE TO A FRONTAL BOUNDARY IN THE AREA AND A STRONG 120KT JET ALOFT. FURTHER EAST...LLVL MOISTURE HAS REMAINED OVER THE HIGH PLAINS WITH GOOD RADIATIONAL COOLING. THIS HAS RESULTED IN SOME LIGHT MIST OR PATCHY FOG...MAINLY ALONG THE FRONT RANGE FROM CHEYENNE NORTHWARD TO DOUGLAS. ADDED PATCHY FOG TO THE FORECAST THIS MORNING...INCLUDING THE LOWER ELEVATIONS OF WESTERN NEBRASKA. MODELS IN GOOD AGREEMENT THROUGH THE WEEKEND SHOWING THE SAME PACIFIC FRONT...WHICH BROUGHT SEVERE WEATHER TO PORTIONS OF SOUTHEAST WYOMING AND WRN NEBRASKA YESTERDAY...PUSHING EASTWARD ACROSS THE AREA LATER TODAY AND TONIGHT AS ANOTHER DISTURBANCE ALOFT QUICKLY EJECTS NORTHEAST OVER MONTANA. AS A RESULT...WINDS WILL SHIFT MORE INTO THE WEST AND SOUTHWEST BRINGING DRIER AIR TO MOST OF THE REGION. PROBABILITY OF PRECIP AND TSTORMS IS EXPECTED TO BE LOWER TODAY...ESPECIALLY FROM CONVERSE COUNTY EASTWARD INTO NW NEBRASKA. STILL CAN NOT RULE OUT AN ISOLATED SHOWER OR TSTORM AS THE FRONT AND ASSOCIATED STRONG JET PUSH ACROSS THE AREA TODAY AND THIS EVENING. WITH MARGINAL INSTABILITY AND DRIER CONDITIONS...EXPECT TSTORMS TO BE MUCH WEAKER TODAY. TEMPS WILL WARM WELL ABOVE NORMAL AHEAD OF THE FRONT MAINLY EAST OF THE LARAMIE RANGE WITH HIGHS IN THE MID 70S TO MID 80S EXPECTED. WINDS WILL BECOME BREEZY OUT OF THE SOUTHWEST AS WELL...WITH 20 TO 35 MPH SUSTAINED WINDS EXPECTED OVER THE HIGH PLAINS OF WYOMING AND MOUNTAINS. BY SUNDAY...MODELS SHOW A DEEP UPPER LEVEL TROUGH ACROSS THE SOUTHERN GREAT BASIN REGION BEGINNING TO EJECT QUICKLY NORTHEASTWARD AS A STRONG RIDGE OF HIGH PRESSURE REMAINS OVER THE MISSISSIPPI RIVER VALLEY. THE TROUGH IS EXPECTED TO BECOME NEGATIVELY TILTED AS IT PUSHES INTO THE CNTRL AND NRN ROCKIES INTO EARLY MONDAY MORNING. EXPECT PRECIP AND TSTORMS CHANCES TO INCREASE LATE SUNDAY AND INTO SUNDAY NIGHT WITH STRONG NOCTURNAL TSTORMS POSSIBLE ACROSS PORTIONS OF SOUTHEAST WYOMING AND WRN NEBRASKA. INCREASED POP LATE SUNDAY AND SUNDAY NIGHT...ESPECIALLY NORTH OF I80 WHERE THE BEST CHANCE OF PRECIP AND HEAVY RAIN IS EXPECTED. SUNDAY WILL BE COOLER AFTER THE FRONT MOVES THROUGH THE AREA...WITH TEMPS CLOSER TO NORMAL. .LONG TERM...MONDAY THROUGH FRIDAY...THE 22/00Z NAM...GFS AND ECMWF ARE IN GENERAL AGREEMENT EJECTING THE NEGATIVE TILT TROUGH NNE ACROSS THE NRN/CNTRL ROCKIES/HIGH PLAINS MONDAY THROUGH TUESDAY...WITH AN INTENSIFYING CLOSED LOW MOVING FROM ERN MT INTO MANITOBA CANADA. MONDAY...EXPECT NMRS SHWRS/SCT TSTMS ACROSS NRN CONVERSE/NIOBRARA COUNTIES...TAPERING TO ISOLD ALONG THE CO STATE LINE. CANNOT RULE OUT SOME STRONG STORMS...WITH THE BEST CHANCE FOR SEVERE WEATHER ACROSS THE ERN NEB PANHANDLE INTO THE DAKOTAS WHERE DEEPER MOISTURE/BEST THERMODYNAMICS WILL RESIDE. TEMPS WILL BE NEAR CLIMO NORMS WITH 60S/70S E AND 40S/50S W. ON TUESDAY...MID/UPPER FLOW BECOMES SWLY AS NEXT TROUGH APPROACHES THE PACIFIC COAST. AFTERNOON AND EVENING CONVECTIVE COVERAGE WILL BE ISOLD E OF THE LARAMIE RANGE INTO THE NEB PANHANDLE. LITTLE CHANGE IN HIGH TEMPS FROM MONDAY. ON WEDNESDAY...ISOLD AFTERNOON AND EVENING THUNDERSTORMS WILL DEVELOP N OF A RWL-CYS-SNY LINE IN LOW LEVEL SELY UPSLOPE FLOW. 850-700MB THERMAL RIDGE BEGINS TO SET UP WITH HIGHS FROM THE 50S/60S W TO 70S/NEAR 80 E. THE WARMING TREND CONTINUES ON THURSDAY WITH INCREASING HEIGHTS ALOFT AND 1000-500 MB THICKNESSES RESULTING IN UPPER 70S AND LOWER 80S E OF THE LARAMIE RANGE. WARMING ALOFT WILL INHIBIT MOST CONVECTIVE DEVELOPMENT...WITH ISOLD TSTMS POSSIBLE OVER NRN PORTIONS OF THE CWA. FINALLY ON FRIDAY...MID/UPPER RIDGE DOMINATES THE HIGH PLAINS/GREAT PLAINS STATES...FURTHER SUPPRESSING CONVECTIVE DEVELOPMENT AND PROMOTING ABOVE CLIMO TEMPS. && .AVIATION...06Z TAF ISSUANCE LOW CIGS AND VSBYS HAVE DEVELOPED INVOF CYS SHORTLY AFTER 06Z...AND WILL LIKELY BE TEMPORARY DUE TO SWLY FLOW. PORTIONS OF THE NEB PANHANDLE WILL SEE MVFR CIGS AND VSBYS DEVELOPING TOWARD MORNING. AREAS TO THE W OF THE LARAMIE RANGE WILL REMAIN VFR WITH INTERVALS OF AC/CI CLOUDS. WINDS WILL INCREASE AT LAR AND RWL TOWARD MORNING...AND SPREAD E AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING COLD FRONT. THE LOW CIGS AND VSBYS WILL GIVE WAY TO SCT CU AND SCT-BKN CI CLOUDS LATER THIS MORNING. ISOLD SHWRS/TSTMS WILL DEVELOP ALONG AND JUST E OF THE LARAMIE RANGE THIS AFTERNOON/EARLY EVE AS THE COLD FRONT MOVES THROUGH. THEN GUSTY WINDS WILL SHIFT FROM SW TO W-NW FOLLOWING FROPA. && .FIRE WEATHER...SOMEWHAT DRIER CONDITIONS ARE EXPECTED TODAY AS SURFACE WINDS SHIFT MORE INTO THE SOUTHWEST AHEAD OF THE NEXT PACIFIC DISTURBANCE WHICH WILL PUSH INTO THE GREAT BASIN REGION THIS WEEKEND. DAYTIME MINIMUM HUMIDITIES WILL LOWER INTO THE UPPER TEENS TO MID 20S WITH GUSTY SOUTHWEST WINDS BETWEEN 15 TO 30 KTS THROUGH THIS AFTERNOON WITH LOCALLY HIGHER GUSTS. CAN NOT RULE OUT AN ISOLATED THUNDERSTORM...GENERALLY NORTH OF I80 INTO THIS EVENING. FIRE WEATHER CONCERNS REMAIN LOW...DUE TO HIGH FUEL MOISTURE IN THE AREA AND LOW TO MODERATE FIRE DANGER...MAINLY DUE TO RECENT HEAVY RAINS. A PACIFIC COLD FRONT WILL PASS THROUGH THE AREA LATE SATURDAY...RESULTING IN COOLER TEMPERATURES AND A DECENT CHANCE OF SHOWERS AND TSTORMS SUNDAY THROUGH EARLY NEXT WEEK. && .HYDROLOGY...ELEVATED RIVERS AND STREAMS RESULTING FROM RECENT HEAVY RAINS AND MOUNTAIN SNOW MELT ARE EXPECTED TO CONTINUE INTO THE WEEKEND. A FLOOD WATCH REMAINS IN EFFECT FOR SOUTHWEST CARBON COUNTY THROUGH THIS EVENING. OBSERVATIONS OF INCREASED FLOWS ALONG THE SAVERY CREEK AND TRIBUTARIES FLOWING INTO THE LITTLE SNAKE RIVER NEAR BAGGS HAVE DECREASED SLIGHTLY BUT MAY INCREASE AGAIN TODAY DUE TO SNOWMELT. OTHER AREA RIVERS HAVE REMAINED BELOW ACTION STAGE AND ARE EXPECTED TO REMAIN BELOW ACTION STAGE THROUGH THE WEEKEND. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...FLOOD WATCH UNTIL MIDNIGHT SUNDAY FOR WYZ111. NE...NONE. && SHORT TERM/FIRE WEATHER...TJT LONG TERM/AVIATION...JAMSKI HYDROLOGY...JAMSKI/TJT
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 440 AM MDT SAT MAY 22 2010 NEZ002-003-019>021-054-055-095-096-WYZ101>119-231045- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS- NIOBRARA COUNTY-NORTH LARAMIE RANGE- FERRIS/SEMINOE/SHIRLEY MOUNTAINS-SHIRLEY BASIN- CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- EAST PLATTE COUNTY-GOSHEN COUNTY-CENTRAL CARBON COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTHWEST CARBON COUNTY- SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE- LARAMIE VALLEY-SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 440 AM MDT SAT MAY 22 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE...EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...TODAY AND TONIGHT AN UPPER LEVEL DISTURBANCE AND APPROACHING COLD FRONT WILL TRIGGER ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS...MAINLY NORTH AND WEST OF A LINE FROM ALLIANCE TO CHEYENNE. SEVERE THUNDERSTORMS ARE NOT EXPECTED. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP SUNDAY AND MONDAY AS A SERIES OF UPPER LEVEL DISTURBANCES MOVE NORTHEAST ACROSS THE REGION. STRONG STORMS WILL BE POSSIBLE MONDAY...ESPECIALLY EAST OF THE LARAMIE RANGE INTO THE NEBRASKA PANHANDLE. ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY AND WEDNESDAY...WITH LITTLE OR NO PRECIPITATION EXPECTED THURSDAY AND FRIDAY AS A UPPER LEVEL RIDGE BUILDS OVER THE PLAINS. MOREOVER...WARMER TEMPERATURES WILL CAUSE AN INCREASE IN SNOW MELT AND WHEN COMBINED WITH LOCALLY HEAVY RAINFALL FROM THUNDERSTORMS...MAY RESULT IN INCREASED RIVER AND STREAM LEVELS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE JAMSKI
The national radar mosaic for the moment the first event began.
4 high wind. Local standard time, as filed.
Sustained winds at or above 40 mph and gusts have been in excess of 60 mph since 700MST. According to law enforcement trees have been blown down and there are widespread power outages in Laramie.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2010Every state in 2010This day in weather historyWarnings in Wyoming, May 2010
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: 226668, 226666, 226667, 226669.