Monsoon moisture allowed thunderstorms to form over much of western Wyoming. The strongest storms produced severe winds at Cody and Pinedale.
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.
Monsoon moisture allowed thunderstorms to form over much of western Wyoming. The strongest storms produced severe winds at Cody and Pinedale.
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 Jul 19, 12:44 PM MST, 5 hours 51 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 144 PM MDT TUE JUL 19 2011 SHORT TERM...TONIGHT THROUGH FRIDAY SUBTROPICAL MOISTURE PLUME CONTINUES OVER THE AREA WITH SOME MID LEVEL DRYING WORKING INTO THE FAR WEST. THUNDERSTORMS FIRING ACROSS THE CENTRAL ZONES ATTM WITH A COUPLE STRONG CELLS. DISTURBANCES IN THE FLOW ARE GENERALLY GOING TO STAY JUST SOUTHEAST OF OUR AREA IN NORTHERN COLORADO AND SOUTHEAST WYOMING. HOWEVER...ENOUGH HEATING HAS OCCURRED TO COMBINE WITH 40 TO 50 DEW POINTS TO PRODUCE AN ACTIVE AFTERNOON AND EVENING OF CONVECTION. THE FAR WEST...IS A ANOTHER CHALLENGE. THE AFOREMENTIONED MID LEVEL DRYING HAS OCCURRED BUT THE SURFACE MOISTURE IS REMAINING. IN ADDITION...THE APPROACHING COLD FRONT AND UPPER JET STREAK WILL PROVIDE INCREASING DYNAMICS BY EARLY EVENING. THIS AREA WILL HAVE TO BE WATCHED THROUGH THE EVENING HOURS FOR SOME STRONGER CELLS. THE APPROACHING SHORTWAVE THEN SUPPRESSES THE SUBTROPICAL PLUME TO THE SOUTH FOR A COUPLE DAYS WITH LITTLE OR NO CONVECTION ACROSS THE FORECAST AREA THROUGH THURSDAY. DID LEAVE IN THE ISOLATED ACROSS SOUTHEASTERN SWEETWATER WEDNESDAY AFTERNOON JUST IN CASE THE PLUME IS NOT TOTALLY SUPPRESSED SOUTH OF US. OTHERWISE...THE NEXT CHANCE OF THUNDERSTORMS WILL SPREAD INTO THE NORTHWEST ON FRIDAY WITH THE APPROACH OF THE NEXT SHORTWAVE DIGGING INTO THE PACIFIC NORTHWEST AND NORTHERN GREAT BASIN. SOME OF THESE STORMS COULD BE QUITE STRONG. A TAD COOLER BEHIND THIS FRONT ON WEDNESDAY THEN IT WILL WARM UP ONCE AGAIN THURSDAY AND FRIDAY. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY DRY...BREEZY/WINDY AND VERY WARM WEATHER PREVAIL ACROSS MOST OF THE AREA FRIDAY. A COLD FRONT WILL PUSH ACROSS THE NORTH FRIDAY NIGHT AND BRING SLIGHTLY COOLER AND DRY WEATHER ON SATURDAY. MAINLY DRY WEATHER...LIGHT WIND...AND ABOVE NORMAL TEMPERATURES FOLLOW SUNDAY AND MONDAY. CHANCES OF SHOWERS AND THUNDERSTORMS RETURN TO THE WEST ON TUESDAY. UPPER LOW OVER SOUTHERN ALASKA EARLY THIS MORNING WILL DIVE SOUTH AND BOTTOM OUT OVER SOUTHERN BRITISH COLUMBIA THURSDAY...AND THEN LIFT INTO STRONG DOWNSTREAM RIDGE ACROSS CENTRAL CANADA. LESS SPREAD EXISTS BETWEEN 00Z TUE MODEL RUNS WITH GFS DETERMINISTIC REMAINING ON THE SLOW END OF GUIDANCE. CONSENSUS IS TOWARD THE FAST END OF GUIDANCE WITH UPPER LOW ACROSS EASTERN ALBERTA BY 00Z SATURDAY. MONSOONAL TAP IS SUPPRESSED TO THE SOUTH AND EAST AHEAD OF THIS TROUGH...WITH MOISTURE/LIFT CLIPPING THE NORTH LATE FRIDAY. AFTERWARDS...UPPER TROUGH SHARPENS ALONG 130W OVER THE WEEKEND WITH UPPER HIGH/RIDGE BUILDING DOWNSTREAM OVER THE ROCKIES. GFS/GEFS MEAN OFFER THE MOST CONSISTENT SOLUTION WITH HIGH CENTER OVER CO/NM MONDAY WHILE THE ECMWF IS SHOWS BROADER RIDGE ACROSS THE SOUTHERN U.S. WITH HIGH CENTER FURTHER EAST. FORECAST WEIGHTED TOWARD GFS MORE CONSISTENT SOLUTION. THUS...ABOVE NORMAL TEMPERATURES RETURN SUNDAY AND MONDAY WITH JUST SLIGHT CHANCES OF LATE DAY CONVECTION IN THE VICINITY OF BIG HORN MOUNTAINS AND EAST. 130W UPPER TROUGH BEGINS TO PUSH INLAND TUESDAY WITH SOME MONSOONAL MOISTURE PULLED NORTHWARD ACROSS WESTERN WYOMING. GFS ALSO PULLS UP THERMAL RIDGE (20C AT H7...36C AT H85) ACROSS CENTRAL WYOMING TUESDAY...A SCENARIO THAT WOULD RESULT IN NEAR RECORD HEAT WITH SOME TRIPLE DIGITS. AVIATION... A PROMINENT PACIFIC SHORTWAVE TROUGH OF LOW PRESSURE WILL TRACK ACROSS WYOMING THROUGH TONIGHT. THIS WILL RESULT IN SCATTERED THUNDERSTORMS ACROSS MUCH OF WESTERN AND CENTRAL WYOMING LATE THIS AFTERNOON WITH NUMEROUS THUNDERSTORMS EXPECTED ACROSS MUCH OF SWEETWATER COUNTY INCLUDING KRKS...THE UPPER GREEN RIVER BASIN INCLUDING KPNA AS WELL AS THE WIND RIVER MOUNTAINS...THE SALT AND WYOMING RANGES AND THE BIG HORN MOUNTAINS. THESE STORMS WILL BE CAPABLE OF LOCALLY HEAVY RAINFALL AND SMALL HAIL RESULTING IN LOCAL MVFR AND ISOLATED IFR CONDITIONS. SCATTERED THUNDERSTORMS WILL CONTINUE THROUGH THIS EVENING. RAPID CLEARING IS EXPECTED BEHIND THE TROUGH AXIS AFTER MIDNIGHT WITH ANY SCATTERED THUNDERSTORMS LIMITED TO NORTHWEST WYOMING INCLUDING KPNA AND KJAC. VFR CONDITIONS ARE EXPECTED WEDNESDAY. FIRE WEATHER... AN ACTIVE AFTERNOON AND EVENING OF THUNDERSTORMS WILL BE REPLACED BY MUCH DRIER CONDITIONS WEDNESDAY THROUGH THURSDAY. IT WILL CONTINUE QUITE WARM WITH DRIER MIN RH'S THE NEXT COUPLE AFTERNOONS IN THE TEENS. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...SKRBAC LONG TERM...AEM AVIATION...LIPSON FIRE WEATHER...SKRBAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MDT TUE JUL 19 2011 WYZ001>020-022>030-201100- 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 TUE JUL 19 2011 ...FLOOD ADVISORY IN EFFECT THROUGH WEDNESDAY AFTERNOON FOR THE SHOSHONE RIVER IN PARK COUNTY DOWNSTREAM OF BUFFALO BILL RESERVOIR... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT RIVERS AND CREEKS WILL REMAIN HIGH AND SWIFT IN MANY AREAS...FOR AT LEAST THE NEXT SEVERAL DAYS. HOWEVER...OVER THE NEXT SEVERAL DAYS...MOST OF THE RIVERS AND CREEKS WILL CONTINUE TO SLOWLY RECEDE. ONLY LOCALIZED MINOR FLOODING OF MAINLY AGRICULTURE OR LOW LYING AREAS ARE EXPECTED. SHOWERS AND THUNDERSTORMS EXPECTED THROUGHOUT THE DAY WITH COVERAGE INCREASING THIS AFTERNOON. SHOWER AND THUNDERSTORMS MAY PERSIST INTO THE EARLY EVENING HOURS TONIGHT. STORM ACTIVITY WILL HAVE THREATS OF GUSTY WIND TO 45 MPH...SMALL HAIL AND PERIODS OF MODERATE TO HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH SUNDAY WEDNESDAY THROUGH FRIDAY...BREEZY TO WINDY...WARM AND VERY DRY CONDITIONS WILL INCREASE THE FIRE DANGER ACROSS SOUTH AND CENTRAL WYOMING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. TEAM RIVERTON
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
503 PM MDT TUE JUL 19 2011
WYZ027-200000-
SOUTH LINCOLN COUNTY WY-
503 PM MDT TUE JUL 19 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LINCOLN COUNTY UNTIL
600 PM MDT...
AT 454 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 12 MILES WEST OF U.S. HWY 189 MILE MARKER 10...OR
13 MILES NORTHEAST OF EVANSTON...MOVING NORTHEAST AT 30 MPH.
HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.
THIS STORM WILL BE NEAR...
DIAMONDVILLE AND KEMMERER AROUND 540 PM MDT.
OPAL AROUND 555 PM MDT.
IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.
BRIEF HEAVY RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES
AND NORMALLY DRY WASHES...IS ALSO POSSIBLE. DO NOT DRIVE YOUR
VEHICLE ON A FLOODED ROADWAY.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4186 11053 4188 11023 4169 11010 4157 11035
4158 11096
TIME...MOT...LOC 2302Z 225DEG 31KT 4148 11079
MURRELLSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 504 PM MDT TUE JUL 19 2011 WYZ001-012-013-192345- JACKSON HOLE WY-TETON AND GROS VENTRE MOUNTAINS WY-YELLOWSTONE NATIONAL PARK WY- 504 PM MDT TUE JUL 19 2011 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL TETON COUNTY IN NORTHWEST WYOMING UNTIL 545 PM MDT... AT 455 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A CLUSTER OF STRONG THUNDERSTORM 7 MILES SOUTHWEST OF TETONIA IDAHO...OR 7 MILES WEST OF DRIGGS IDAHO...MOVING NORTHEAST AT 45 MPH. PEA SIZE HAIL AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH SOME OF THESE STORMS...ALONG WITH LOCALLY HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. THIS STORM WILL BE NEAR... GIBSON MEADOWS AROUND 530 PM MDT. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. BRIEF HEAVY RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO POSSIBLE. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. IF OUT HIKING IN THE AREA MOUNTAINS...SEEK SHELTER AT THE FIRST SIGN OF THREATENING WEATHER TO AVOID EXPOSURE TO LIGHTNING. IF OUT BOATING ON AREA LAKES...HEAD TO SHORE AT THE FIRST SIGN OF THREATENING WEATHER. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4423 11105 4436 11097 4391 11024 4347 11105 TIME...MOT...LOC 2259Z 209DEG 38KT 4379 11122 LIPSON
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
544 PM MDT TUE JUL 19 2011
WYZ001-002-012-013-200045-
ABSAROKA MOUNTAINS WY-JACKSON HOLE WY-TETON AND GROS VENTRE MOUNTAINS
WY-YELLOWSTONE NATIONAL PARK WY-
544 PM MDT TUE JUL 19 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN YELLOWSTONE NATIONAL
PARK AND NORTHERN TETON COUNTY IN NORTHWEST WYOMING UNTIL 645 PM
MDT...
AT 537 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 15 MILES SOUTHWEST
OF OLD FAITHFUL...TO NEAR THE SOUTH ENTRANCE TO JENNY LAKE
LODGE...MOVING NORTHEAST AT 40 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THESE STORMS...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.
THESE STORMS WILL BE NEAR...
LEWIS LAKE AND COULTER BAY VILLAGE AROUND 545 PM MDT.
SHOSHONE LAKE AROUND 555 PM MDT.
GRANT VILLAGE AND OLD FAITHFUL AROUND 600 PM MDT.
IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.
BRIEF HEAVY RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES
AND NORMALLY DRY WASHES...IS ALSO POSSIBLE. DO NOT DRIVE YOUR
VEHICLE ON A FLOODED ROADWAY.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4488 11037 4470 10995 4430 10980 4409 11005
4389 11009 4380 11036 4373 11065 4414 11081
4424 11105 4443 11105
TIME...MOT...LOC 2341Z 227DEG 36KT 4434 11101 4421 11070
4389 11058
MURRELLSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 623 PM MDT TUE JUL 19 2011 WYZ023>030-200145- EAST SWEETWATER COUNTY-FLAMING GORGE-ROCK SPRINGS AND GREEN RIVER- SALT RIVER AND WYOMING RANGES-SOUTH LINCOLN COUNTY-STAR VALLEY- UPPER GREEN RIVER BASIN-UPPER GREEN RIVER BASIN FOOTHILLS- 623 PM MDT TUE JUL 19 2011 THROUGH 8 PM...ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO AFFECT SOUTHWEST WYOMING...INCLUDING STAR VALLEY...UPPER GREEN RIVER BASIN...SWEETWATER AND SOUTHERN LINCOLN COUNTIES. THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING GUSTY WINDS OF 50 MPH...BRIEF HEAVY RAINFALL...FREQUENT LIGHTNING AND SMALL HAIL. 21
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
631 PM MDT TUE JUL 19 2011
WYZ001-002-012-200115-
ABSAROKA MOUNTAINS WY-TETON AND GROS VENTRE MOUNTAINS WY-YELLOWSTONE
NATIONAL PARK WY-
631 PM MDT TUE JUL 19 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN PARK AND EASTERN TETON
COUNTIES IN NORTHWEST WYOMING UNTIL 715 PM MDT...
AT 627 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 16 MILES NORTHEAST OF U.S. HWY 287/26 MILE MARKER
20...OR 28 MILES NORTHEAST OF MORAN JUNCTION...MOVING NORTHEAST AT 40
MPH.
WIND GUSTS UP TO 45 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH
FREQUENT DANGEROUS LIGHTNING.
THIS STORM WILL MAINLY AFFECT THE SOUTHERN ABSAROKA MOUNTAINS...BUT
COULD AFFECT THE SMALL COMMUNITY OF VALLEY AROUND 700 PM MDT.
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 4451 10956 4428 10952 4395 10922 4397 10984
4397 10994 4402 11006 4394 11006 4391 11011
4421 11037
TIME...MOT...LOC 0029Z 240DEG 36KT 4401 10996
MURRELLSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
730 PM MDT TUE JUL 19 2011
WYZ002-015-016-200215-
ABSAROKA MOUNTAINS WY-UPPER WIND RIVER BASIN WY-WIND RIVER MOUNTAINS
EAST WY-
730 PM MDT TUE JUL 19 2011
...SIGNIFICANT WEATHER ADVISORY FOR WESTERN HOT SPRINGS...EXTREME
SOUTHERN PARK AND NORTHWESTERN FREMONT COUNTIES UNTIL 815 PM MDT...
AT 726 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR DUBOIS...MOVING NORTHEAST AT 40 MPH.
WIND GUSTS UP TO 45 MPH...WITH BRIEF HEAVY RAINFALL ARE EXPECTED
WITH THIS STORM.
THIS STORM WILL BE NEAR...
TORREY LAKE AROUND 735 PM MDT.
WASHAKIE NEEDLES AROUND 815 PM MDT.
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 4397 10930 4377 10899 4336 10965 4350 10979
4356 10990
TIME...MOT...LOC 0130Z 229DEG 33KT 4351 10965
MURRELLThe Riverton/Lander radar (KRIW), 112 km away, was scanning. The volume nearest the first event began at 01:35 UTC.
2 thunderstorm wind. Local standard time, as filed.
A strong thunderstorm produced a 58 mph wind gust at Ralph Wenz Field south of Pinedale.
Wind damage was reported in and east of Cody as a result of outflow wind from collapsing thunderstorms. A recreational trailer was toppled at a residence and large limbs were felled at another causing damage to an automobile and power lines.
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, July 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: 329951, 329952.