The high waters at the confluence of the Lamar River and Soda Butte Creek combined to undercut and damage a 200-foot-section of Yellowstone National Park's Northeast Entrance road. The first extended period of warm weather caused melting of a large late-season snowpack which increased flow in both channels.
Every event with a place to put it. 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 RIW wrote it up.
The high waters at the confluence of the Lamar River and Soda Butte Creek combined to undercut and damage a 200-foot-section of Yellowstone National Park's Northeast Entrance road. The first extended period of warm weather caused melting of a large late-season snowpack which increased flow in both channels. Flow on the Lamar River peaked on Friday, June 24, at around 11,000 cfs and crested near 9.5 feet. Only the eastbound lane of the road was impacted, but the erosion still necessitated complete closure of the road on June 24, while repairs were made. A second smaller section of the road was also damaged by the high water downstream from the larger washout. Crews used nearly 100 loads of rock and fill dirt to repair and stabilize the road which reopened to traffic the evening of Wednesday, June 29.
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 Jun 24, 2:07 PM MST, 4 hours 53 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 307 PM MDT FRI JUN 24 2011 .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT CYCLONIC SOUTHWEST FLOW WILL BRING UNSTABLE MOIST AIR OVER WESTERN AND CENTRAL WYOMING TONIGHT THROUGH SATURDAY NIGHT. SCATTERED SHOWERS AND THUNDERSTORMS WILL RESULT. A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 9 PM MDT THIS EVENING FOR CENTRAL AND EASTERN AREAS. TEMPERATURES WILL BE SLIGHTLY COOLER SATURDAY WITH SOME WARMING ON SUNDAY WITH FEWER CLOUDS OVER THE AREA. SOME DRYING IS EXPECTED SUNDAY...HOWEVER THE MODELS HAVE NOT DONE WELL WITH THE COVERAGE AND INTENSITY OF CONVECTION BOTH DAY TIME AND NIGHT TIME. OROGRAPHIC LIFT AND UPPER LEVEL DIVERGENCE HAVE PLAYED IN THE DEVELOPMENT OF CONVECTION. THE CONVECTION ON SUNDAY MAY BE MORE WIDESPREAD THAN CURRENTLY FORECAST. .LONG TERM...MONDAY THROUGH FRIDAY MAINLY DRY CONDITIONS EXPECTED MONDAY AND TUESDAY WITH SEASONABLY COOL WEATHER LINGERING EAST OF THE DIVIDE MONDAY...AND MORE SUMMER-LIKE TEMPERATURES IN THE 80S TO NEAR 90 ON TAP FOR THE VALLEYS AND BASINS ON TUESDAY. THE MAIN WEATHER MAKER IN THIS PERIOD WILL MOVE ACROSS THE AREA WEDNESDAY NIGHT AND THURSDAY WITH ISOLATED TO SCATTERED THUNDERSTORMS AHEAD OF THIS SYSTEM WEDNESDAY/WEDNESDAY NIGHT LIFTING INTO NORTHERN WYOMING ON THURSDAY. MAINLY DRY CONDITIONS AND SEASONABLY COOL CONDITIONS WILL FOLLOW ON FRIDAY. MEDIUM-RANGE GLOBAL MODELS ARE IN MUCH BETTER AGREEMENT THIS MORNING THROUGH THURSDAY WITH INCREASING SPREAD LATE IN THE PERIOD. UPPER RIDGE BUILDS INTO THE NORTHERN ROCKIES ON MONDAY AS UPPER LOW DROPS SOUTH ALONG 130W OFF THE NORTHWEST COAST. LOW BOTTOMS OUT ALONG 40N BEFORE PUSHING ONSHORE TUESDAY NIGHT. BOTH GFS AND ECMWF HAVE UPPER LOW NEAR RENO BY 00Z THURSDAY...HOT UPPER HIGH CENTERED OVER OKLAHOMA AND DIFLUENT FLOW IN BETWEEN OVER WYOMING. UPPER LOW THEN OPENS UP AND LIFTS NE ACROSS THE NORTHERN GREAT BASIN WEDNESDAY NIGHT AND ACROSS WYOMING ON THURSDAY. AFTERWARDS...GFS/GEFS MEAN SHOW BROAD CYCLONIC FLOW OVER THE NORTHERN ROCKIES WITH UPPER HIGH REMAINING OVER THE CENTRAL PLAINS. ECMWF ATTEMPTS TO RETROGRADE HIGH BACK INTO FOUR CORNERS AREA ON FRIDAY. FORECAST WEIGHTED TOWARD GFS/PERSISTENCE IN THIS LATTER PERIOD. && .AVIATION... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BRING PERIODS OF MVFR/IFR CIGS WITH MOUNTAIN OBSCURATIONS TO MUCH OF THE AREA THROUGH 06Z SATURDAY. ERRATIC WIND WILL BE COMMON WITH SCATTERED TO NUMEROUS THUNDERSTORMS...PARTICULARLY FOR AREAS EAST OF THE CONTINENTAL DIVIDE. VFR CONDITIONS WILL RESUME AFTER 06Z AS SHOWERS AND THUNDERSTORMS DECREASE IN COVERAGE AND INTENSITY. VFR CONDITIONS WILL REMAIN ON SATURDAY WITH A FEW SHOWERS DEVELOPING AFTER 18Z. && .HYDROLOGY... THE WIND RIVER FROM DUBOIS TO RIVERTON CONTINUES TO RISE WITH FLOOD WARNINGS IN EFFECT. THE GREEN RIVER FROM WARREN BRIDGE TO FONTENELLE CONTINUES TO RISE AND IS EXPECTED TO BE NEAR FLOOD STAGE BY TUESDAY. THE FORKS OF THE SHOSHONE CONTINUE TO RISE AS WELL WITH A FLOOD WATCH THROUGH SUNDAY EVENING. SHELL CREEK AREA HAS RECEIVED FROM .5 TO 1 INCH OF RAIN COMBINING WITH 2 INCHES OF SNOW MELT RUN OFF AND FLOODING IS EXPECTED THIS EVENING. SMALL CREEKS AND HEADWATER STREAMS THAT ARE ALREADY FLOWING AT MODERATE TO HIGH LEVELS ARE EXPECTED TO RUN ABOVE BANKFULL THROUGH SUNDAY. WARMER MOUNTAIN TEMPERATURES TODAY WILL INCREASE SNOWMELT BELOW 10000 FEET. RUN OFF HAS BEEN BETWEEN 1.5 AND 2 INCHES FROM THIS SNOW PACK AND IS EXPECTED TO CONTINUE AROUND THIS RATE. SCATTERED THUNDERSTORMS ARE EXPECTED MAINLY ACROSS NORTHERN AND EASTERN WYOMING THIS EVENING. COOLER TEMPERATURES WILL PREVAIL ACROSS NORTHERN WYOMING SATURDAY WHILE TEMPERATURES WILL REMAIN WARM ACROSS THE SOUTH. THE BEST POTENTIAL FOR SIGNIFICANT RAIN PRODUCING THUNDERSTORMS WILL BE ACROSS NATRONA AND JOHNSON COUNTIES SATURDAY AFTERNOON AND EVENING. SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE MORE ISOLATED SUNDAY WITH NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES ACROSS THE NORTHERN BASINS AND NEAR OR ABOVE NORMAL TEMPERATURES ACROSS THE SOUTH. && .RIW WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM MIDNIGHT MDT TONIGHT THROUGH SUNDAY EVENING WYZ002>004-008>010-012. && SHORT TERM...C.BAKER LONG TERM...AEM AVIATION...BERC FIRE WEATHER...TEAM RIVERTON HYDROLOGY...C.BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 658 PM MDT FRI JUN 24 2011 WYZ001>020-022>030-251300- 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- 658 PM MDT FRI JUN 24 2011 ...FLOOD WARNING FOR THE WIND RIVER FROM DUBOIS TO RIVERTON AND FOR SMALLER CREEKS AND RIVERS OF BIG HORN COUNTY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...REST OF TONIGHT ISOLATED THUNDERSTORMS WILL PREVAIL THROUGH SUNSET. MOST OF THE STORMS WILL BE CONFINED TO AREAS SOUTH OF A LINE FROM AFTON TO RIVERTON TO CASPER. EXCESSIVE SNOWMELT DUE TO WARM TEMPERATURES WILL CAUSE RISING WATER LEVELS ON THE WIND RIVER FROM FROM DUBOIS THROUGH RIVERTON. FLOODING IS LIKELY IN LOW LYING AREAS ADJACENT TO THE WIND RIVER. OTHER FLOODING IS POSSIBLE ON SMALLER CREEKS AND RIVERS OF SOUTHEAST BIG HORN COUNTY AROUND MANDERSON...HYATTVILLE...AND SHELL. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THUNDERSTORMS WILL MAINLY BE CONFINED TO NORTHERN WYOMING FOR THE WEEKEND. THE STORMS WILL BE LESS WIDESPREAD AND INTENSE THAN IN RECENT DAYS. THUNDERSTORM COVERAGE WILL BEGIN TO BECOME MORE WIDESPREAD BY THE MIDDLE OF NEXT WEEK AS MOISTURE SURGES INTO THE STATE AHEAD OF ANOTHER WEATHER SYSTEM. CREEKS AND RIVERS WILL CONTINUE TO RUN HIGH AND SWIFT AS MOUNTAIN SNOWPACK CONTINUES TO MELT THROUGH THE WEEKEND. THE WIND RIVER... SHOSHONE RIVER...AND BIG HORN RIVER BASINS WILL BE MOST SUSCEPTIBLE TO THE HIGH RUNOFF. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT HAIL...GUSTY WIND...AND FLOODING TO THE NATIONAL WEATHER SERVICE AT 1-800-211-1448. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
246 PM MDT FRI JUN 24 2011
WYZ014>019-025-026-242130-
GREEN MOUNTAINS AND RATTLESNAKE RANGE WY-LANDER FOOTHILLS WY-UPPER
GREEN RIVER BASIN WY-UPPER GREEN RIVER BASIN FOOTHILLS WY-UPPER WIND
RIVER BASIN WY-WIND RIVER BASIN WY-WIND RIVER MOUNTAINS EAST WY-WIND
RIVER MOUNTAINS WEST WY-
246 PM MDT FRI JUN 24 2011
...SIGNIFICANT WEATHER ADVISORY FOR EASTERN SUBLETTE AND CENTRAL
FREMONT COUNTIES UNTIL 330 PM MDT...
AT 242 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR HUDSON...OR 11 MILES SOUTHWEST OF
RIVERTON...MOVING EAST AT 35 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM.
THIS STORM WILL BE NEAR...
FREMONT COUNTY FAIRGROUNDS AROUND 255 PM MDT.
STATE HWY 135 MILE MARKER 10 AROUND 305 PM MDT.
GAS HILLS RD MILE MARKER 10 AROUND 310 PM MDT.
GAS HILLS RD MILE MARKER 20 AROUND 325 PM MDT.
A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM MDT FRIDAY
EVENING FOR NORTH CENTRAL WYOMING.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4334 10927 4336 10843 4280 10774 4227 10919
4331 10993
TIME...MOT...LOC 2046Z 260DEG 32KT 4291 10848
LAVOIESPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
342 PM MDT FRI JUN 24 2011
WYZ002-007-014>019-025-026-242245-
ABSAROKA MOUNTAINS WY-GREEN MOUNTAINS AND RATTLESNAKE RANGE WY-LANDER
FOOTHILLS WY-OWL CREEK AND BRIDGER MOUNTAINS WY-UPPER GREEN RIVER
BASIN WY-UPPER GREEN RIVER BASIN FOOTHILLS WY-UPPER WIND RIVER BASIN
WY-WIND RIVER BASIN WY-WIND RIVER MOUNTAINS EAST WY-WIND RIVER
MOUNTAINS WEST WY-
342 PM MDT FRI JUN 24 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN HOT SPRINGS...EASTERN
SUBLETTE AND FREMONT COUNTIES UNTIL 445 PM MDT...
AT 336 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
STRONG THUNDERSTORMS OVER THE AREA...MOVING NORTHEAST AT 30
MPH.
WIND GUSTS UP TO 50 MPH...AND PEA SIZED HAIL...ARE EXPECTED WITH
THIS STORM.
THESE STORMS MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO
AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR
ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL
WEATHER SERVICE.
A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM MDT FRIDAY
EVENING FOR NORTH CENTRAL WYOMING.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4364 10915 4348 10759 4249 10755 4226 10935
4288 10985
TIME...MOT...LOC 2139Z 245DEG 28KT 4292 10865
LAVOIESPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
413 PM MDT FRI JUN 24 2011
WYZ019-020-022-242245-
CASPER MOUNTAIN WY-GREEN MOUNTAINS AND RATTLESNAKE RANGE WY-NATRONA
COUNTY LOWER ELEVATIONS WY-
413 PM MDT FRI JUN 24 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN NATRONA COUNTY UNTIL
445 PM MDT...
AT 411 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 9 MILES EAST OF HWY 487 MILE MARKER 50...OR 23
MILES SOUTH OF CASPER...MOVING NORTHEAST AT 35 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM.
THIS STORM WILL BE OVER AND SOUTH OF CASPER MOUNTAIN AND OVER RURAL
PORTIONS OF SOUTHEASTERN NATRONA COUNTY.
IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4243 10632 4261 10652 4283 10613 4283 10608
4244 10607
TIME...MOT...LOC 2212Z 236DEG 29KT 4253 10622
JONESSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 512 PM MDT FRI JUN 24 2011 WYZ030-250000- EAST SWEETWATER COUNTY WY- 512 PM MDT FRI JUN 24 2011 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL SWEETWATER COUNTY UNTIL 600 PM MDT... AT 506 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 7 MILES NORTHEAST OF STATE HWY 430 MILE MARKER 20...OR 20 MILES EAST OF ROCK SPRINGS...MOVING NORTHEAST AT 30 MPH. WIND GUSTS UP TO 50 MPH...AND PEA SIZED HAIL...ARE EXPECTED WITH THIS STORM. THIS STORM WILL BE NEAR... I80 EXIT 136 AROUND 530 PM MDT. I80 EXIT 139 AROUND 535 PM MDT. BITTER CREEK REST AREA AND I80 EXIT 142 AROUND 540 PM MDT. I80 EXIT 146 AROUND 545 PM MDT. I80 EXIT 150 AROUND 550 PM MDT. I80 EXIT 152...I80 EXIT 154 AND TABLE ROCK AROUND 555 PM MDT. I80 EXIT 156 AND I80 EXIT 158 AROUND 600 PM MDT. THIS INCLUDES INTERSTATE 80 IN WYOMING BETWEEN MILE MARKERS 134 AND 161. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4182 10829 4149 10813 4141 10888 4157 10897 TIME...MOT...LOC 2311Z 247DEG 28KT 4153 10881 LAVOIE
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 649 PM MDT FRI JUN 24 2011 WYZ019-030-250115- EAST SWEETWATER COUNTY WY-GREEN MOUNTAINS AND RATTLESNAKE RANGE WY- 649 PM MDT FRI JUN 24 2011 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN SWEETWATER AND EXTREME SOUTHEASTERN FREMONT COUNTIES UNTIL 715 PM MDT... AT 642 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 10 MILES NORTHEAST OF CHAIN LAKES...OR 26 MILES SOUTH OF JEFFREY CITY...MOVING NORTHEAST AT 25 MPH. WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM. THIS STORM WILL BE NEAR... BAIROIL AROUND 715 PM MDT. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4216 10785 4230 10752 4209 10751 4200 10773 TIME...MOT...LOC 0049Z 241DEG 20KT 4213 10768 LAVOIE
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
732 PM MDT FRI JUN 24 2011
WYZ019-020-022-250230-
CASPER MOUNTAIN WY-GREEN MOUNTAINS AND RATTLESNAKE RANGE WY-NATRONA
COUNTY LOWER ELEVATIONS WY-
732 PM MDT FRI JUN 24 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN NATRONA COUNTY UNTIL 830
PM MDT...
AT 729 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
STRONG THUNDERSTORMS OVER NORTHERN CARBON COUNTY. THESE STORMS WERE
MOVING NORTHEAST AT 35 MPH.
DANGEROUS CLOUD-TO-GROUND LIGHTNING...WIND GUSTS OF 40 TO 50 MPH...
AND PEA SIZED HAIL ARE ALL EXPECTED WITH THESE STORMS.
THESE STORMS WILL BE NEAR...
DEVIL'S GATE AROUND 735 PM MDT.
U.S. HWY 220 MILE MARKER 60 AROUND 740 PM MDT.
INDEPENDENCE ROCK AROUND 745 PM MDT.
PATHFINDER RESERVOIR BY 800 PM MDT.
ALCOVA AROUND 810 PM MDT.
BOATERS ON PATHFINDER AND ALCOVA RESERVOIRS ARE STRONGLY ENCOURAGED
TO HEAD TO SHORE AND SEEK SAFE SHELTER INDOORS. THE GUSTY WIND AND
LIGHTNING WILL MAKE ACTIVITES ON AND AROUND THE RESERVOIRS HAZARDOUS.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4243 10608 4243 10754 4252 10754 4294 10693
4258 10607
TIME...MOT...LOC 0129Z 229DEG 30KT 4249 10745 4207 10646
JONESThe national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
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: 325522.