A strong Pacific upper level low pressure system brought strong winds to the Absaroka Mountains and the southern wind corridor from Rock Springs to Casper. These winds were followed by heavy snows in the far west mountains, where 12 to 21 inches was reported.
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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.
A strong Pacific upper level low pressure system brought strong winds to the Absaroka Mountains and the southern wind corridor from Rock Springs to Casper. These winds were followed by heavy snows in the far west mountains, where 12 to 21 inches was reported.
High winds were observed periodically on both Monday, March 29, and Tuesday, March 30. In Clark, 13 cottonwood trees were toppled and a home had two-thirds of its roof removed around 0200MST Monday. A peak gust to 84 mph was measured on Chief Joseph Pass later that morning. High wind was also reported on Monday across western Natrona County.
On Tuesday, sustained winds of 40 mph with occasional gusts near 60 mph were observed in eastern Sweetwater County. The peak gust at the Rock Springs-Sweetwater County Airport ASOS registered 68 mph with the passage of a cold front around 1630MST. Afternoon peak gusts of 59 mph and 62 mph were recorded at Jeffrey City and Casper-Natrona County International Airport, respectively.
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 Mar 29, 2:25 AM MST, 6 hours 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 325 AM MDT MON MAR 29 2010 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT ACTIVE PATTERN CONTINUES TO COME TOGETHER THIS MORNING AS A STRONG 160+KT JET MOVES ON SHORE AND INTO THE NORTHERN ROCKIES. THE JET IS ASSOCIATED WITH THE LARGE PACIFIC TROUGH SPINNING OFF THE PACIFIC N AMERICAN COAST. THE INITIAL AND CONTINUING IMPACT WILL BE STRONG WIND AND THE SECOND WILL BE SIGNIFICANT PRECIPITATION IN THE WEST. FOR THE WIND...GOOD DOWNWARD FORCING UNDER THE JET'S RIGHT EXIT REGION WILL COMBINE WITH A TIGHT GRADIENT ACROSS WYOMING TO PRODUCE WINDY TO EVEN STRONG WINDS OVER MUCH OF THE CWA. HIGH WINDS ARE EXPECTED TODAY AND TONIGHT OVER THE ABSAROKAS AND CODY FOOTHILLS...AS WELL AS SOUTHEAST FREMONT AND NATRONA COUNTIES. BOTH NAM AND GFS SHOWING H7 WINDS OF 50+KTS AS WELL AS A 7 TO 10 MB SURFACE GRADIENT OVER THESE AREAS. THE STRONGEST WINDS WILL LIKELY OCCUR DURING THE LATE EVENING AND EARLY MORNING HOURS TONIGHT...WITH THE STRONGEST H7 WINDS AS WELL AS THE TIGHTEST GRADIENT OCCURRING THEN. WILL UPGRADE THE HIGH WIND WATCH FOR THE CENTRAL WIND CORRIDOR TO A WARNING AT ISSUANCE...9AM TODAY THROUGH NOON TUESDAY. WILL ALSO ALLOW THE ABSAROKA AND CODY FOOTHILL WARNING TO RUN ITS COURSE...6AM TODAY THROUGH 6AM TUESDAY. WINDY TO VERY WINDY CONDITIONS EXPECTED MOST OTHER AREAS OF WESTERN AND CENTRAL WYOMING TODAY AND TUESDAY AS WELL. AS FOR THE SNOW...MOISTURE WILL INCREASE OVER THE NORTHWEST TODAY WITH SOME LIGHT RAIN FALLING...SNOW ABOVE 9000 FEET...THIS MORNING AND AFTERNOON. THE PRECIPITATION WILL GRADUALLY SPREAD SOUTH OVERNIGHT TONIGHT WITH SNOW LEVELS FALLING TO OR NEAR THE VALLEY FLOORS. STRONG OROGRAPHIC LIFT...ISENTROPIC UPGLIDE AS WELL AS SHORTWAVE DYNAMICS WILL ALLOW THE RAIN/SNOW TO PERSIST TONIGHT AND TUESDAY ACROSS THE WEST. DECENT MOISTURE FETCH WILL REMAIN OPEN FROM OFF THE OR/WA COASTS THROUGH THIS PERIOD. UNCERTAINTY EXISTS WHERE EXACTLY THE SNOWLINE WILL BE AS TEMPERATURES IN THE VALLEYS WILL BE AT THE RAIN/SNOW CHANGE OVER POINT. FOR NOW...WILL ALLOW THE GOING FORECAST OF SNOW TO RIDE. SIGNIFICANT MOISTURE IS EXPECTED...AND IN THE MOUNTAINS 10 TO 20 INCHES OF SNOWFALL IS POSSIBLE WITH 4 TO 8 INCHES IN THE VALLEYS IF THE PRECIP IS ALL SNOW. WILL ALLOW WINTER STORM WATCH TO RIDE AS IS. COLD FRONT MOVES INTO NORTHERN WYOMING TUESDAY AFTERNOON/EARLY EVENING BRINGING SOME RAIN AND MOUNTAIN SNOW THERE. LOOKS LIKE A QUICK SHOT SO SHOULD NOT NEED HIGHLIGHTS. FRONT GETS PUSHED BACK NORTH ON WEDNESDAY AS THE NEXT JET ASSOCIATED WITH THE TROUGH TAKES A FURTHER SOUTH ROUTE INTO THE GREAT BASIN...RE-ENFORCING THE SOUTHWEST TO WEST FLOW. IT WILL REMAIN WINDY MOST AREAS TUESDAY NIGHT AND WEDNESDAY. THE COLD FRONT DRIVES SOUTH AGAIN WEDNESDAY EVENING WITH A DECENT CHANCE OF SOME UPSLOPE SNOW DEVELOPING OVER THE CENTRAL AND SOUTH. .LONG TERM...THURSDAY THROUGH MONDAY MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH A MID LEVEL CIRCULATION/SHORTWAVE TROUGH...ON THE EASTERN PART OF A MEAN TROUGH OVER THE WEST/ROCKIES...PUSHING ACROSS THE COWBOY STATE ON THURSDAY. THIS MID LEVEL CIRCULATION WILL RESULT IN A DECENT CHANCE FOR PRECIPITATION OVER THE SOUTH...AND EAST OF THE DIVIDE. THE 00Z GFS REMAINS PERSISTENT IN PRODUCING DECENT UPSLOPE IN WAKE OF THIS MID LEVEL CIRCULATION...WHILE THE OTHER MODELS KEEP MORE OF A NORTHWEST/WEST COMPONENT. PRECIPITATION ON THURSDAY...SHOULD BE MAINLY SNOWFALL...AS 700MB TEMPS ARE PROJECTED TO BE -5 DEG CELSIUS OR COLDER THURSDAY MORNING...WITH SLIGHT COLD AIR ADVECTION DURING THE DAY. AFTER THURSDAY...THE MAIN EMPHASIS WITH THIS TROUGH WILL SHIFT WELL SOUTH OF THE AREA...WITH A CLOSED LOW PUSHING ACROSS ARIZONA/NEW MEXICO INTO THE SOUTHERN PLAINS FRIDAY. HOWEVER...WILL KEEP SLIGHT TO LOW CHANCE POPS GOING THURSDAY NIGHT/FRIDAY TO RESPECT THE MEAN TROUGH...AND THE POSSIBILITY OF A WEAK DISTURBANCES MOVING ACROSS THE AREA. IN WAKE OF THIS MEAN TROUGH...A MAINLY ZONAL FLOW IS EXPECTED TO DEVELOP FROM THE PACIFIC TO THE ROCKIES FRIDAY NIGHT THROUGH SATURDAY NIGHT. THE 00Z ECMWF AND GEM SHOW A DISTURBANCE IN THIS FLOW AFFECTING THE AREA ON SATURDAY...WHILE THE 00Z GFS CONTINUES TO LIFT THIS FEATURE ACROSS MONTANA/SOUTHERN CANADA. WILL HAVE POPS OVER THE WEST AND NORTH...WITH BETTER CHANCES OVER NORTHWEST WYOMING FOR THIS SYSTEM. FLOW BEGINS TO BACK ON SUNDAY IN RESPONSE TO A TROUGH/UPPER LOW DIGGING OFF THE WEST COAST. IN RESPONSE TO THIS BACKING FLOW...WARMER 700 MB TEMPERATURES WILL QUICKLY MOVE NORTHEAST INTO THE AREA SUNDAY...WITH 700MB TEMPS BETWEEN +2 AND -2 DEG CELSIUS. THE TROUGH APPROACHES THE ROCKIES ON MONDAY...WITH THE MAIN ENERGY ASSOCIATED WITH AN UPPER LOW PUSHING INTO THE DESERT SOUTHWEST. SOUTHWEST FLOW AHEAD OF THE MEAN TROUGH/UPPER LOW WILL CONTINUE TO PUSH WARMER TEMPS INTO THE AREA...AND A CHANCE OF CONVECTION OVER THE WEST. TEMPERATURES ARE EXPECTED TO BE BELOW AVERAGE THURSDAY AND FRIDAY...WITH ABOVE AVERAGE TEMPERATURES EXPECTED IN MOST LOCATIONS SUNDAY AND MONDAY. && .AVIATION... WINDY WEATHER WILL BE THE MAIN AVIATION HAZARD TODAY INTO THIS EVENING AT MOST OF THE AIRPORTS. KCPR...KCOD...AND KRKS WILL SEE THE STRONGEST WIND SPEEDS AND GUSTS. OTHERWISE VFR CONDITIONS WILL PREVAIL TODAY AND THIS EVENING OVER THE AREA. IN NW WY CLOUDS WILL BE INCREASING AND LOWERING DURING THE AFTERNOON WITH SCATTERED RAIN AND SNOW SHOWERS DEVELOPING BY 21Z. AFTER 00Z IN NW WY A GREATER COVERAGE OF RAIN AND SNOW WILL OCCUR WITH MVFR CONDITIONS AND INCREASING MOUNTAIN OBSCURATION. SOME OF THIS PRECIPITATION WILL MAKE IT INTO THE KJAC AIRPORT AROUND 00Z TUE WITH RAIN SHOWERS...THEN A MIX OF RAIN AND SNOW SHOWERS AROUND 06Z TUE WITH POSSIBLE MVFR CONDITIONS. && .FIRE WEATHER... STRONG WINDS ARE EXPECTED TODAY ACROSS MUCH OF THE AREA AND TUESDAY WITH HIGH WIND WARNINGS IN EFFECT FOR PORTIONS OF THE DISTRICT. THESE AREAS INCLUDE SOUTHEAST FREMONT AND NATRONA COUNTIES...AS WELL AS THE ABSAROKAS AND CODY FOOTHILLS. THE WINDS WILL COMBINE WITH MILD TEMPERATURES AND LOW RH'S EAST OF THE DIVIDE TO INCREASE THE FIRE WEATHER DANGER. MOISTURE WILL BUILD INTO THE WEST TODAY WITH SOME RAIN AND SNOW SHOWERS DEVELOPING...BECOMING WIDESPREAD OVER THE NORTHWEST BY LATE AFTERNOON. THE PRECIPITATION WILL SPREAD INTO SOUTHWEST WYOMING OVERNIGHT. SNOW LEVELS WILL INITIALLY BE AROUND 9000 FEET TODAY...THEN DESCEND TO NEAR THE VALLEY FLOORS OVERNIGHT. THE RAIN/SNOW WILL PERSIST OVER THE WEST INTO TUESDAY EVENING. NUMEROUS WINTER STORM WATCHES ARE IN EFFECT TONIGHT AND TUESDAY OVER THE FAR WEST. A COLD FRONT COULD BRING THE PRECIP EAST OF THE DIVIDE TUESDAY NIGHT AND WEDNESDAY NIGHT. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM 6 AM THIS MORNING TO 6 AM MDT TUESDAY WYZ002-003. WINTER STORM WATCH FROM THIS EVENING THROUGH LATE TUESDAY NIGHT WYZ001-012>014-023-024. HIGH WIND WARNING FROM 9 AM THIS MORNING TO NOON MDT TUESDAY WYZ019-020. && SHORT TERM...TWB LONG TERM...WM AVIATION...AR FIRE WEATHER...TWB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MDT MON MAR 29 2010 WYZ001>020-022>030-301200- 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- 500 AM MDT MON MAR 29 2010 ...WINTER STORM WATCHES ARE IN EFFECT FOR MUCH OF FAR WESTERN WYOMING AND THE WEST SLOPES OF THE WIND RIVER MOUNTAINS TONIGHT THROUGH EARLY WEDNESDAY MORNING... ...HIGH WIND WARNING IS IN EFFECT FOR THE EAST SLOPES OF THE ABSAROKA MOUNTAINS AND THE CODY FOOTHILLS THROUGH 6 AM TUESDAY... ...HIGH WIND WARNING IS IN EFFECT FOR SOUTHEAST FREMONT AND THE LOWER ELEVATIONS OF NATRONA COUNTY FROM 9 AM TODAY THROUGH NOON TUESDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT STRONG WEST TO SOUTHWEST WINDS WILL DEVELOP ACROSS SOUTHEAST FREMONT COUNTY...LOWER ELEVATIONS OF NATRONA COUNTY...CODY FOOTHILLS...AND THE EAST SLOPES OF THE ABSAROKA MOUNTAINS THIS MORNING. SOUTHWEST TO WEST WINDS OF 35 TO 45 MPH WITH GUSTS OF 60 MPH OR GREATER ARE EXPECTED OVER LOWER ELEVATIONS...WITH 45 TO 55 MPH WITH GUSTS UP TO 75 MPH ARE EXPECTED OVER THE ABSAROKAS AND AROUND CLARK. STRONG WINDS ARE ALSO EXPECTED ALONG THE EAST SLOPES OF THE WIND RIVER MOUNTAINS WITH SUSTAINED WEST OT SOUTHWEST WINDS OF 40 TO 50 MPH WITH GUSTS UP TO 70 MPH. THE REST OF CENTRAL AND WESTERN WYOMING BE QUITE WINDY TODAY AND TONIGHT. WIDESPREAD SNOW IS EXPECTED IN THE MOUNTAINS OF WESTERN WYOMING TONIGHT THROUGH TUESDAY NIGHT...WITH SIGNIFICANT SNOWFALL EXPECTED. NUMEROUS WINTER STORM WATCHES ARE IN EFFECT FOR TONIGHT THROUGH TUESDAY NIGHT. SNOW LEVELS WILL INITIALLY BE AROUND 9000 FEET...BUT WILL DESCEND TO NEAR THE VALLEY FLOORS BY TUESDAY MORNING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE STRONG WINDS WILL BEGIN TO WIND DOWN...BUT WILL REMAIN QUITE WINDY. THE SNOW WILL PERSIST...POSSIBLY HEAVY AT TIMES...OVER WESTERN WYOMING TUESDAY AND BEGIN TO WIND DOWN TUESDAY NIGHT. SNOWFALL ACCUMULATIONS OF 10 TO 25 INCHES COULD OCCUR OVER THE WESTERN MOUNTAINS...WITH 5 TO 10 INCHES IN THE LOWER ELEVATIONS. EAST OF THE DIVIDE WILL MAINLY BE IMPACTED BY THIS SYSTEM WEDNESDAY AND THURSDAY...WITH SIGNIFICANT SNOWFALL POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT WIND GREATER THAN 40 MPH AS WELL AS SNOWFALL OVER 2 INCHES. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 647 AM MDT MON MAR 29 2010 WYZ005-292000- SOUTHWEST BIG HORN BASIN- 647 AM MDT MON MAR 29 2010 ...WINDY WEATHER FOR TODAY... STRONG SOUTHWEST WINDS BETWEEN 20 AND 35 MPH...WITH GUSTS BETWEEN 40 AND 55 MPH WILL BE COMMON TODAY ACROSS HOT SPRINGS COUNTY...INCLUDING THERMOPOLIS. MOTORISTS SHOULD BE PREPARED FOR THESE STRONG AND SUDDEN WIND GUSTS. LIGHT WEIGHT AND HIGH PROFILE VEHICLES SHOULD EXERCISE EXTREME CAUTION. 21
The national radar mosaic for the moment the first event began.
7 high wind, 3 winter storm. 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, March 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: 215050, 215049, 215051, 215052, 215046, 215047, 215048, 215846, 215856, 215855.