Water levels which climbed from a Memorial Day winter-like storm receded below flood stage on the Blacks Fork River (see May 2011 Storm Data publication for more information).
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The episode as NWS RIW wrote it up.
Water levels which climbed from a Memorial Day winter-like storm receded below flood stage on the Blacks Fork River (see May 2011 Storm Data publication for more information).
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 May 31, 2:36 PM MST, 9 hours 24 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 336 PM MDT TUE MAY 31 2011 .SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT A HIGH PRESSURE RIDGE WILL SLOWLY SHIFT EAST WITH INCREASING SOUTHWEST FLOW OVER WESTERN AND CENTRAL WYOMING. WITH WARMER WINDY CONDITIONS THIS WILL PROVIDE CONDITIONS FOR SIGNIFICANT SNOW MELT WEDNESDAY INTO EARLY FRIDAY WITH A SIGNIFICANT INCREASE IN RUN OFF INTO STREAMS AND RIVERS. AS THE RIDGE MOVES EAST OUT OF THE AREA...A PACIFIC LOW PRESSURE TROUGH WILL MOVE INTO THE WEST THURSDAY WITH INCREASING CLOUDS AND SHOWERS...AND ISOLATED THUNDERSTORMS OVER THE WEST. COOLER TEMPERATURES WILL SPREAD FROM WEST TO EAST THROUGH THURSDAY NIGHT. THE WESTERN MOUNTAINS AND VALLEYS SHOULD SEE BELOW FREEZING TEMPERATURES WHICH WILL STOP THE SNOW MELT IN THE MOUNTAINS. TEMPERATURES WILL BE THE MOST SIGNIFICANT FORECAST AS IT IMPACTS SNOW MELT AND FLOODING THREATS ACROSS THE AREA. REFER TO THE FLOOD WATCH AND FLOOD WARNINGS IN EFFECT AND THOSE THAT MAY BE ISSUED OVER THE NEXT FEW DAYS FOR MORE DETAILS ON THE FLOODING. .LONG TERM...FRIDAY THROUGH TUESDAY THE TROUGH MOVES THROUGH WY ON FRIDAY BRINGING SOME WIND AND COOLER TEMPS TO THE REGION. THE BEST CHANCE OF SHOWERS AND STORMS WILL BE OVER THE NORTH WHERE THE BEST LIFT LOOKS TO OCCUR. THE ACTIVITY OVER THE NORTH ENDS FRIDAY EVENING. OTHERWISE DRY FRIDAY NIGHT. SATURDAY AND SATURDAY NIGHT LOOK DRY WITH SOUTHWEST FLOW ALOFT. THE NEXT UPPER LEVEL STORM SYSTEM DROPS SOUTH ALONG THE WEST COAST OF THE U.S. SATURDAY AND MOVES INTO CALIFORNIA SUNDAY. THE ECMWF IS FASTER WITH THIS THAN THE GFS. IN FACT THE ECMWF EJECTS THIS SYSTEM INTO THE GREAT BASIN SUNDAY NIGHT AND INTO IDAHO FOR MONDAY AND INTO MONTANA MONDAY NIGHT. THE GFS IS SLOWER WITH THIS PROGRESSION BY ABOUT ONE DAY. THE LACK OF AN UPSTREAM KICKER ON THE ECMWF IS CONCERNING WHILE THE GFS DOES NOT HAVE MUCH OF A KICKER EITHER. HAVE DECIDED TO TAKE A BLENDED TIMING OF THE NEXT SYSTEM FOR NOW AND WOULD NOT BE SURPRISED IF THE SYSTEM IS SLOWER TO MOVE INTO THE REGION. SLIGHT CHANCE OF SHOWERS AND STORMS LOOKS OK IN THE WEST SUNDAY AFTERNOON AND SUNDAY NIGHT WITH ISOLATED ACTIVITY AT BEST EAST OF THE DIVIDE. THEN HAVE INCREASED THE CHANCE OF SHOWERS AND THUNDERSTORMS MONDAY AND TUESDAY AS THE SYSTEM MOVES TOWARD AND THROUGH THE NORTHERN ROCKIES. EXPECT BREEZY TO WINDY CONDITIONS MONDAY AND TUESDAY. HIGH TEMPS WILL WARM UP SATURDAY AND SUNDAY. MONDAY MAY STILL BE WARM IN THE CENTRAL AND EAST ZONES WHILE THE WEST SHOULD BE COOLER DUE TO MORE CLOUDS AND PRECIP. COOLER ALL AREAS NEXT TUESDAY IF THE STORM SYSTEM DOES INDEED MOVES THROUGH THE AREA. THUS SNOW MELT SHOULD INCREASE THIS COMING WEEKEND INTO EARLY NEXT WEEK BASED ON THIS FORECAST PACKAGE. STAY TUNED. && .AVIATION... EXCEPT FOR ISOLATED SHOWERS THIS AFTERNOON AND WEDNESDAY AFTERNOON...EXPECT VFR CONDITIONS TO PREVAIL. && .HYDROLOGY... WARMER WINDY CONDITIONS WILL PROVIDE CONDITIONS FOR SIGNIFICANT SNOW MELT WEDNESDAY INTO EARLY FRIDAY WITH A SIGNIFICANT INCREASE IN RUN OFF INTO STREAMS AND RIVERS. COOLER TEMPERATURES ARE EXPECTED TO DECREASE SNOW MELT AND RUN OFF FRIDAY AND FRIDAY NIGHT. TEMPERATURES WILL THEN CLIMB ON SATURDAY WITH A PROLONGED WARM UP SUNDAY...MONDAY AND TUESDAY WITH ANOTHER PERIOD OF SIGNIFICANT RUN OFF INCREASE AND STREAM AND RIVER RESPONSE EXPECTED. A FLOOD WATCH HAS BEEN ISSUED TO ADDRESS THE FIRST WARM UP PERIOD STARTING AT 6 PM WEDNESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM WEDNESDAY EVENING THROUGH FRIDAY AFTERNOON WYZ001>020-022>030. && SHORT TERM...C.BAKER LONG TERM...AR AVIATION...LIPSON FIRE WEATHER...TEAM RIVERTON HYDROLOGY...C.BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 101 PM MDT TUE MAY 31 2011 WYZ001>020-022>030-011100- 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- 101 PM MDT TUE MAY 31 2011 ...A FLOOD WARNING IS IN EFFECT FOR THE BLACKS FORK RIVER AND ITS TRIBUTARIES NEAR LITTLE AMERICA...AFFECTING THE TOWN OF GRANGER IN SWEETWATER COUNTY... ...A FLOOD WARNING REMAINS IN EFFECT FOR THE SALT RIVER AND ITS TRIBUTARIES IN STAR VALLEY... ...A FLOOD WATCH IS IN EFFECT FOR ALL OF WESTERN AND CENTRAL WYOMING FROM WEDNESDAY EVENING THROUGH FRIDAY AFTERNOON DUE TO RAPID SNOW MELT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY WARMER TEMPERATURES ARE STILL FORECAST FOR WEDNESDAY AND THURSDAY. THIS HAS PROMPTED THE ISSUANCE OF A FLOOD WATCH FOR ALL OF WESTERN AND CENTRAL WYOMING AS A RESULT OF RAPID SNOW MELT IN THE MOUNTAINS BELOW 9000 FEET FEEDING AREA HEADWATER SMALL CREEKS AND STREAMS. COOLER HIGHS ARE FORECAST FOR FRIDAY. THIS WOULD TEMPORARILY SLOW THE RATE OF SNOW MELT IN THE HIGHER MOUNTAINS. THEN TEMPERATURES ARE TO WARM AGAIN SATURDAY AND SUNDAY. THIS WOULD INCREASE THE RATE OF SNOW MELT THIS COMING WEEKEND INTO EARLY NEXT WEEK. STAY TUNED FOR UPDATES AND ADDITIONAL INFORMATION. A CHANCE OF THUNDERSTORMS OVER THE NORTHWEST QUARTER OF WYOMING THURSDAY AND THURSDAY NIGHT AS A COLD FRONT MOVES THROUGH THAT AREA. ISOLATED THUNDERSTORMS ARE POSSIBLE EAST OF THE CONTINENTAL DIVIDE THURSDAY AFTERNOON AND NIGHT AS THE COLD FRONT PUSHES THROUGH THIS REGION. THERE WILL BE A CHANCE OF SHOWERS AND ISOLATED STORMS OVER THE NORTH ON FRIDAY. .SPOTTER INFORMATION STATEMENT... SPOTTERS...PLEASE REPORT ANY FLOODING ALONG RIVERS...CREEKS AND STREAMS. PLEASE REPORT ANY SNOWFALL AMOUNTS. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Water levels on the Blacks Fork River retreated below flood stage as snowmelt run-off and rainfall from the previous weekend progressed downstream. Other than lowland flooding, there was no impact to public or private property.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2011Every state in 2011This day in weather historyWarnings in Wyoming, June 2011
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: 316839.