Johnson County experienced a strong northerly wind in the wake of a large upper level low pressure system. Gusts to 61 mph were observed at Johnson County Airport in Buffalo.
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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 RIW wrote it up.
Johnson County experienced a strong northerly wind in the wake of a large upper level low pressure system. Gusts to 61 mph were observed at Johnson County Airport in Buffalo. Stronger gusts to 66 mph were recorded by a weather station along Interstate 25 south of Buffalo.
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 Riverton, WY wrote its last area forecast discussion before the first event at Apr 23, 7:31 AM MST, 3 hours 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 831 AM MDT FRI APR 23 2010 .UPDATE... SENT OUT A FORECAST UPDATE TO INCREASE WIND IN THE BIGHORN BASIN AND OWL CREEK MOUNTAINS. MANY SFC OBS SITES REPORTING WIND GUSTS INTO THE 40-45 MPH RANGE WITH HALF DEGREE VELOCITY PRODUCT INDICATING 50-55KTS OF NORTHERLY WIND NEAR MOUNTAIN TOP LEVEL OVER THE OWL CREEKS. REDUCED PRECIP CHANCES OVER NORTHWEST WYOMING SOUTHEASTWARD INTO THE UPPER WIND RIVER BASIN AS LATEST SRF INDICATING DRY MID-LEVEL AIR ADVECTING INTO THIS AREA SLIGHTLY FASTER THAN PREVIOUSLY THOUGHT. ALL IN ALL...A WET DAY IN STORM FOR MANY AREAS TODAY WITH NICE WRAP AROUND TROWEL FEATURE PUMPING IN LOW LEVEL GULF OF MEXICO MOISTURE FROM THE SOUTHEAST. && .PREV DISCUSSION... /ISSUED 325 AM MDT FRI APR 23 2010/ SHORT TERM...TODAY THROUGH SUNDAY NIGHT RATHER COMPLEX STORM SYSTEM OVER THE GREAT BASIN AND SOUTHERN/ CENTRAL ROCKIES THIS MORNING. THE UPPER LOW CENTER BEGINNING TO SPIN UP OVER SOUTHEAST COLORADO AFTER JUMPING THE DIVIDE. H7 LOW AND SURFACE LOW TO DEVELOP UNDER THIS AREA AS WELL. DEFORMATION AXIS OVER NORTHERN AND WEST CENTRAL WYOMING AND EASTERN IDAHO WITH NUMEROUS SHOWERS OVER THESE AREAS...INCLUDING THE WIND RIVER BASIN. AS THE LOW SPINS UP FURTHER LATER THIS MORNING...A NORTH UPSLOPE FLOW DEVELOPS OVER WYOMING. THE WIND WILL BE BREEZY TO WINDY MOST AREAS...ESPECIALLY EAST OF THE DIVIDE. WRAP AROUND MOISTURE WILL INCREASE OVER THE FAVORED UPSLOPE LOCATIONS...BUT SHOULD BE MOST PROMINENT OVER NATRONA COUNTY INCLUDING CASPER AND CASPER MOUNTAIN. THE EASTERN WINDS WILL CONTINUE TO SEE SNOWFALL ABOVE 7500 FEET THIS MORNING AND AFTERNOON WITH ANOTHER 2 TO 4 INCHES POSSIBLE...SO WILL LET THE ADVISORY GO THROUGH NOON. TEMPERATURES WILL BE TOO WARM INITIALLY FOR SNOW AROUND CASPER MOUNTAIN...EXCEPT ABOVE 8000 FEET. COLDER AIR WRAPS IN THE AFTERNOON WITH SNOW LEVELS FALLING BELOW 7K FEET SO WILL START TO SEE SOME GOOD SNOW FALL. SNOW WILL FALL OVER THE BIGHORNS AS WELL WITH SOME 2 TO 4 INCHES POSSIBLE THERE. THE SNOW WILL WIND DOWN THIS EVENING...TAPERING OFF AFTER MIDNIGHT AS THE UPPER LOW LIFTS OUT INTO THE PLAINS. CASPER MOUNTAIN SHOULD SEE A GOOD 4 TO 8 INCHES SO WILL ISSUE AN ADVISORY THERE...RUNNING FROM 21Z THIS AFTERNOON THROUGH 09Z SATURDAY MORNING. ENOUGH COLD AIR MOVES IN OVERNIGHT SO THAT MANY LOW ELEVATIONS WILL SEE THE RAIN CHANGE TO SNOW...BUT SHOULD BE AFTER THE BULK OF THE PRECIP HAS ALREADY FALLEN. RIDGE BUILDS IN FOR SATURDAY WITH THE NEXT CLIPPER SYSTEM MOVING ONSHORE. THIS SYSTEM WILL PUSH A COLD FRONT INTO NORTHERN WYOMING SATURDAY NIGHT WITH SOME SNOW MOVING INTO THE MOUNTAINS WITH RAIN OVER THE LOWER ELEVATIONS. THE FRONT MOVES INTO CENTRAL WYOMING SUNDAY WITH SOME LIGHT PRECIP MOVING IN AS WELL...WITH MOSTLY SNOW EXPECTED. THE FRONT WASHES OUT SUNDAY NIGHT AS THE CLIPPER MOVES OUT INTO THE PLAINS. LONG TERM...MONDAY THROUGH FRIDAY AN UPPER LOW OVER EASTERN MONTANA IS EXPECTED TO SHEAR OUT AND PUSH SOUTHEAST INTO THE CENTRAL PLAINS. THIS SYSTEM COULD RESULT IN SOME LIGHT PRECIPITATION EAST OF THE DIVIDE...BUT NOTHING MAJOR. A RIDGE BUILDS INTO THE FORECAST AREA LATE MONDAY/MONDAY NIGHT WITH MAINLY DRY CONDITIONS EXPECTED. A SIGNIFICANT TROUGH IS EXPECTED TO DIG ACROSS THE WEST COAST ON TUESDAY. WEAK DIFLUENT FLOW AHEAD OF THE SYSTEM COULD RESULT IN ISOLATED TO LOCALLY SCATTERED CONVECTION TUESDAY...MAINLY WEST OF THE DIVIDE. SOUTHWEST FLOW OUT AHEAD OF THIS SYSTEM WILL USHER IN WARMER TEMPERATURES FOR TUESDAY. 700MB TEMPS ARE PROJECTED TO BE FROM +3 TO +7 DEG CELSIUS BY 00Z WEDNESDAY. HAVE INCREASED MAX TEMPS CONSIDERABLY FOR TUESDAY...BUT NOT AS WARM AS MEX MOS GUIDANCE. IN ADDITION...STRONG SOUTHWEST WINDS ARE EXPECTED IN NORMAL AREAS SUCH AS BETWEEN ROCK SPRINGS TO CASPER. A STRONG SHORTWAVE TROUGH MOVING THROUGH THE LARGER TROUGH WILL SWING ACROSS THE GREAT BASIN AND NORTHERN/CENTRAL ROCKIES TUESDAY NIGHT AND WEDNESDAY. THIS WILL RESULT IN A STRONG COLD FRONT PUSHING THROUGH THE AREA LATE TUESDAY NIGHT AND WEDNESDAY. BY WEDNESDAY NIGHT...700MB TEMPS ARE PROJECTED TO FALL BETWEEN -5 AND -10 DEG CELSIUS. THE STRONG BAROCLINICITY...SOME JET DYNAMICS AND SHORTWAVE TROUGH SHOULD RESULT IN A DECENT CHANCE OF PRECIPITATION TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THE FLOW AT SURFACE AND ALOFT REMAINS MAINLY WESTERLY DURING THIS TIME FRAME...THUS DOWNSLOPING COULD LIMIT THE PRECIPITATION EAST OF THE DIVIDE. BY THURSDAY...MEDIUM RANGE MODELS ARE SHOWING A LARGE TROUGH OVER WESTERN CONUS WITH TWO MAIN UPPER LOWS. ONE DIVING INTO THE WEST COAST AND ANOTHER ONE OVER THE CENTRAL/NORTHERN PLAINS. BY FRIDAY THE WESTERN LOW IS EXPECTED TO BE ACROSS SOUTHERN CALIFORNIA...WHILE THE OTHER LOW IS EXPECTED TO BE ACROSS THE UPPER MIDWEST...WITH A GENERAL TROUGH IN BETWEEN THESE SYSTEMS. MEDIUM RANGE MODELS ARE SHOWING SOME COLD TEMPS ALOFT WITH THE GFS PROJECTING -30 DEG CELSIUS AT 500MB BY 00Z FRIDAY. THESE COLD TEMPS ALOFT COULD EASILY RESULT IN CONVECTION ESPECIALLY DURING THE AFTERNOON AND EVENING IF ANY HEATING CAN TAKE PLACE. FORECASTED HIGH TEMPERATURES THURSDAY AND FRIDAY ARE ASSUMING THAT THE AREA WILL HAVE A GOOD AMOUNT OF SOLAR RADIATION...BUT PRECIP TYPE ON THURSDAY WOULD PRIMARILY BE SNOW. TEMPERATURES IN THE LONG TERM ARE EXPECTED TO WARM UP MONDAY AND TUESDAY...WITH SEASONAL TO SLIGHTLY ABOVE AVERAGE TEMPS ON TUESDAY. BEHIND THE COLD FRONT LATE TUESDAY NIGHT/WEDNESDAY...EXPECT BELOW AVERAGE TEMPERATURES...ESPECIALLY ON DAYTIME MAXES. AVIATION... MVFR AND AREAS OF IFR CONDITIONS IN RAIN AND SNOW...SNOW LEVELS BETWEEN 6KFT AND 7KFT...WIDESPREAD MOUNTAIN OBSCURATIONS WILL PREVAIL THROUGH THE MORNING ACROSS MOST OF THE AREA AS AN UPPER LOW PRESSURE SYSTEM INTENSIFIES OVER EASTERN COLORADO. CONDITIONS WILL GRADUALLY IMPROVE NW-SE WEST OF THE DIVIDE 16Z-20Z TODAY. IMPROVING CONDITIONS WILL LIKEWISE OCCUR FROM NW-SE EAST OF THE DIVIDE FROM 20Z FRI-03Z SAT WITH UPSLOPE PRECIPITATION AND IFR/LIFR CONDITIONS LASTLY LINGERING VCNTY KCPR THROUGH 06Z WITH GRADUAL IMPROVEMENT AFTERWARDS. FIRE WEATHER... THE STORM SYSTEM WILL CONTINUE TO BRING MOISTURE TO THE AREA TODAY AND TONIGHT...WITH SIGNIFICANT MOUNTAIN SNOWFALL EXPECTED...ESPECIALLY IN THE WINDS...CASPER MOUNTAIN...BIGHORNS AND THE SOUTHERN ABSAROKAS. THE SNOW WILL TAPER OFF OVER THE WEST THIS MORNING AND AFTERNOON. LOWER ELEVATIONS WILL SEE DECENT RAINFALL. BREEZY TO WINDY NORTH WINDS WILL INCREASE TODAY OVER MUCH OF THE AREA...THOUGH WILL BE STRONGEST EAST OF THE DIVIDE. THE SYSTEM WILL LIFT OUT TONIGHT WITH DRIER CONDITIONS EXPECTED FOR SATURDAY. A CLIPPER SYSTEM WILL PUSH A COLD FRONT INTO NORTHERN WYOMING SATURDAY NIGHT...MOVING INTO THE CENTRAL DURING THE DAY SUNDAY. SOME LIGHT RAIN/SNOW IS EXPECTED. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM MDT SATURDAY WYZ022. WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY WYZ014-015. && UPDATE...CHURCH SHORT TERM...TWB LONG TERM...WM AVIATION...AEM FIRE WEATHER...TWB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 600 AM MDT FRI APR 23 2010 WYZ001>020-022>030-241200- ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST- BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS- EAST SWEETWATER COUNTY-FLAMING GORGE- GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS- NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN- NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS- ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES- SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN- SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY- TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN- UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST- YELLOWSTONE NATIONAL PARK- 600 AM MDT FRI APR 23 2010 ...WINTER WEATHER ADVISORY FOR THE WIND RIVER MOUNTAINS THROUGH NOON TODAY... ...WINTER WEATHER ADVISORY FOR CASPER MOUNTAIN 3 PM THIS AFTERNOON THROUGH 3 AM SATURDAY MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT A STORM SYSTEM OVER EASTERN COLORADO WILL BRING A MOIST...NORTH UPSLOPE FLOW TO AREAS EAST OF THE DIVIDE TODAY. LOWER ELEVATIONS WILL EXPERIENCE SIGNIFICANT RAINFALL TODAY...POSSIBLY CHANGING TO SNOWFALL THIS EVENING BEFORE ENDING AROUND MIDNIGHT. THE MOUNTAINS ARE EXPECTED TO RECEIVE SIGNIFICANT SNOWFALL. THE WIND RIVER MOUNTAINS WILL PICK UP ANOTHER 2 TO 4 INCHES OF SNOWFALL BEFORE TAPERING THIS AFTERNOON. CASPER MOUNTAIN WILL GET IN ON THE ACTION THIS AFTERNOON WITH 4 TO 8 INCHES EXPECTED. THE BIGHORN...ABSAROKA AND OWL CREEK MOUNTAINS WILL LIKELY PICK UP 2 TO 5 INCHES. THE SNOW WILL TAPER OFF OVERNIGHT TONIGHT. MOUNTAIN HIGHWAYS COULD BECOME SLICK AND SNOWPACKED TODAY...ESPECIALLY OVER THE WIND RIVER MOUNTAINS AND CASPER MOUNTAIN. IN ADDITION...ONE TO THREE INCHES OF SNOW IS POSSIBLE THIS MORNING ACROSS SWEETWATER COUNTY...MAINLY ON GRASSY AND ELEVATED SURFACES SUCH AS BRIDGES AND OVERPASSES. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A STORM SYSTEM IS EXPECTED TO AFFECT THE AREA TUESDAY NIGHT THROUGH AT LEAST THURSDAY. THIS SYSTEM COULD BRING SIGNIFICANT SNOWFALL ACROSS PORTIONS OF THE AREA...ESPECIALLY IN THE MOUNTAINS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL TODAY AND TONIGHT. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 736 AM MDT FRI APR 23 2010 WYZ028-030-231545- ROCK SPRINGS AND GREEN RIVER-EAST SWEETWATER COUNTY- INCLUDING THE CITIES OF...ROCK SPRINGS...GREEN RIVER...WAMSUTTER 736 AM MDT FRI APR 23 2010 PERIODS OF WIDESPREAD MODERATE TO HEAVY SNOW WILL CONTINUE ALONG INTERSTATE 80 FROM NEAR CHURCH BUTTE EAST TO CRESTON JUNCTION. VISIBILITY WILL BE REDUCED BELOW ONE HALF MILE AT TIMES. MOTORISTS ARE URGED TO SLOW DOWN...AND ALLOW EXTRA TIME TO REACH THEIR DESTINATION THIS MORNING. THE SNOW WILL GRADUALLY MIX WITH OR CHANGE OVER TO RAIN LATE THIS MORNING.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 742 AM MDT FRI APR 23 2010 WYZ004-231900- NORTH BIG HORN BASIN- 742 AM MDT FRI APR 23 2010 ...STRONG NORTHWEST WINDS IN THE NORTHERN BIG HORN BASIN THIS MORNING... NORTHWEST WINDS OF 40 TO 50 MPH ARE EXPECTED TO CONTINUE ACROSS THE NORTHERN BIG HORN BASIN THROUGH AROUND 1 PM THIS AFTERNOON. LIGHT TO OCCASIONALLY MODERATE RAINFALL WILL ACCOMPANY THE WIND. THE WIND IS THE RESULT OF A TIGHT SURFACE PRESSURE GRADIENT AROUND THE BACKSIDE OF A STRONG LOW PRESSURE CENTER CENTERED OVER EASTERN COLORADO. AS THE LOW EXITS EASTWARD INTO THE CENTRAL PLAINS...THE WIND SPEEDS WILL BEGIN TO SLOWLY DIMINISH BY EARLY THIS AFTERNOON. LIPSON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 815 AM MDT FRI APR 23 2010 WYZ007-017-231900- OWL CREEK AND BRIDGER MOUNTAINS-WIND RIVER BASIN- 815 AM MDT FRI APR 23 2010 ...STRONG NORTH WINDS IN THE FAR NORTHERN PORTION OF THE WIND RIVER BASIN... NORTH WINDS OF 25 TO 35 MPH WITH GUSTS TO BETWEEN 35 AND 55 MPH ARE EXPECTED ACROSS THE FAR NORTHERN PORTION OF THE WIND RIVER BASIN JUST SOUTH OF THE OWL CREEK MOUNTAINS...PRIMARILY WEST OF BOYSEN RESERVOIR UNTIL AROUND 1 PM EARLY THIS AFTERNOON. THE SOUTH END OF THE WIND RIVER CANYON AROUND BOYSEN DAM WILL EXPERIENCE WIND GUSTS OF UP TO 45 MPH DURING THIS TIME FRAME. A STEADY LIGHT TO MODERATE RAINFALL WILL ACCOMPANY THE WIND. THE WIND IS THE RESULT OF A TIGHT SURFACE PRESSURE GRADIENT AROUND THE BACKSIDE OF A STRONG LOW PRESSURE CENTER CENTERED OVER EASTERN COLORADO. AS THE LOW EXITS EASTWARD INTO THE CENTRAL PLAINS...THE WIND SPEEDS WILL BEGIN TO SLOWLY DIMINISH BY EARLY THIS AFTERNOON. LIPSON
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
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, April 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: 222596, 222595.