A very moist airmass and low-level upslope flow generated low clouds east of the Continental Divide. Early afternoon reports of funnel clouds were received from Fremont and Johnson Counties.
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The episode as NWS RIW wrote it up.
A very moist airmass and low-level upslope flow generated low clouds east of the Continental Divide. Early afternoon reports of funnel clouds were received from Fremont and Johnson Counties.
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 26, 1:36 AM MST, 9 hours 39 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 236 AM MDT THU JUL 26 2007 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT MCS COMPLEX HAS BEEN DECAYING OVER THE PAST SEVERAL HOURS...THOUGH SOME LIGHT RAIN SHOWERS AND MODERATE THUNDERSTORMS EXIST MAINLY OVER NATRONA AND JOHNSON COUNTY. SHORTWAVE HAS BEEN EVIDENT ON RADAR FROM LATE EVENING ON FROM ITS CIRCULATION AND IS CENTERED OVER NORTHWEST NATRONA COUNTY AS OF 07Z. QUITE A BIT OF RAIN FELL THIS PAST EVENING WITH MANY REPORTS OF FLOODING ON THE OUTSKIRTS OF CASPER AND IN THE VICINITY OF RED CANYON. 1.31 INCHES OF RAIN FELL IN THE CITY OF RIVERTON. AIRMASS EAST OF THE DIVIDE NEARLY SATURATED IN MOST LOCATIONS. EXPECT ANOTHER ACTIVE DAY TODAY WITH THE POTENTIAL FOR MORE HEAVY RAIN OVER THE WIND RIVER...BIG HORN...GREEN AND CASPER MOUNTAINS AS WELL AS THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES. LOW LEVEL UPSLOPE FLOW IN THESE LOCATIONS WITH AN ALREADY SATURATED AIRMASS WILL COMBINE WITH MODERATE INSTABILITY TO INCREASE THE POTENTIAL FOR HEAVY RAIN AND THEREFORE SOME FLOODING. SOME SHORTWAVE ACTIVITY WILL MOVE INTO EASTERN IDAHO AND WESTERN WYOMING TODAY...SO SHOULD GET SOME INTERACTION FROM THESE AS WELL. NAM12 SHOWING ANYWHERES FROM 3 TO 5 INCHES OF QPF WITH THE GFS GIVING 1-3 INCHES. EVEN A FRACTION OF THIS COULD BRING ON FLOODING PROBLEMS THIS AFTERNOON AND EVENING. THEREFORE HAVE POSTED FLASH FLOOD WATCH FOR THESE AREAS THROUGH MIDNIGHT TONIGHT. OTHER AREAS EAST OF THE DIVIDE WILL STILL HAVE SOME POTENTIAL FOR FLASH FLOODING...BUT SHOULD NOT BE AS GREAT AS THOSE LISTED ABOVE. BETTER INSTABILITY EXISTS OVER THE WEST...SO COULD SEE SOME DECENT STORMS FIRE THERE. PLENTY OF DEW POINT OUT WEST AND SHOULD HAVE SOME GOOD SOLAR INSOLATION. RIDGE BEGINS TO BUILD IN FOR FRIDAY...THOUGH PLENTY OF MOISTURE AND INSTABILITY AROUND SO EXPECT SCATTERED THUNDERSTORMS MANY AREAS IN THE AFTERNOON AND EVENING. SHOULD START TO SEE SOME BETTER DRYING SATURDAY AS WELL AS MUCH WARMER TEMPERATURES. STILL SOME LINGERING MOISTURE AND INSTABILITY TO BRING THE CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS. .LONG TERM...SUNDAY THROUGH THURSDAY MINOR DIFFERENCES AND CHANGES STARTING TO OCCUR IN EXTENDED FORECAST WITH TREND FOR A FLATTER HIGH PRESSURE RIDE OVER THE WESTERN U.S. AND PROGRESSION ALONG THE POLAR FRONT ACROSS SOUTHERN CANADA FROM GULF OF ALASKA LOW PRESSURE CENTER. LARGER...MORE ORGANIZED TROUGHS NOW EJECTING EAST ACROSS CANADA AND NORTHERN MONTANA. MAIN IMPACT SHIFTING MONSOON MOISTURE TO THE SOUTH A BIT AND BRINGING SOUTH WEAK COOL SURGES FROM CANADA SLIGHTLY COOLING TEMPERATURES. EXTENDED MODELS DIFFER MOST WITH TIMING AND LOCATIONS OF CANADIAN TROUGHS WHILE IN VERY GOOD AGREEMENT WITH RIDGE OVER THE WEST. STILL EXTENDED FORECAST WILL BE LARGELY DOMINATED BY MESOSCALE CONVECTION OVER THE REGION WHICH LARGER SCALE EXTENDED MODELS DO NOT HANDLE WELL OVERALL. && .AVIATION... SHOWERS AND A FEW THUNDERSTORMS WILL PERSIST THE EAST AND CENTRAL PARTS OF THE AREA. LOCAL MVFR CONDITIONS WILL OCCUR IN THIS AREA. SHOWERS WILL RETURN OVER THE WEST THIS MORNING WITH LOCAL MVFR CONDITIONS AND MOUNTAIN OBSCURATIONS IN HEAVIER RAIN SHAFTS. AFTERNOON SHOWERS AND STORMS WILL SPREAD OVER THE AREA MAINLY AFTER 19Z. MVFR TO IFR CONDITIONS WILL OCCUR IN AREAS OF VERY HEAVY RAIN. WIND GUSTS AROUND 30 KNOTS MAY ALSO OCCUR NEAR STORMS. && .FIRE WEATHER... ANOTHER ACTIVE DAY IN STORE ACROSS THE AREA WITH THUNDERSTORMS FIRING AGAIN THIS AFTERNOON AND EVENING. HEAVY RAIN AND LIGHTNING WILL GAIN BE THE PRIMARY THREATS...WITH SOME LOCALIZED FLOODING POSSIBLE. A FLASH FLOOD WATCH IS IN EFFECT FOR THE WIND RIVER MOUNTAINS...GREEN MOUNTAINS...BIG HORN MOUNTAINS...CASPER MOUNTAIN...AND THE LOWER ELEVATIONS OF NATRONA AND JOHNSON COUNTIES THROUGH MIDNIGHT TONIGHT. TEMPERATURES WILL REMAIN ON THE COOLER SIDE TODAY WITH HIGHER RELATIVE HUMIDITIES. A GRADUAL WARMING AND DRYING TREND IS IN STORE BEGINNING FRIDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH THIS EVENING FOR WYZ008>011-015-016- 018>020-022. && SHORT TERM...TWB LONG TERM...C.BAKER AVIATION...AR FIRE WEATHER...TWB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 501 AM MDT THU JUL 26 2007 WYZ001>020-022>030-271101- 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- 501 AM MDT THU JUL 26 2007 ...FLASH FLOOD WATCH IN EFFECT FOR THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES...LANDER FOOTHILLS...WIND RIVER MOUNTAINS...BIG HORN MOUNTAINS...GREEN AND RATTLESNAKE MOUNTAINS AND CASPER MOUNTAIN THROUGH MIDNIGHT TONIGHT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT A VERY MOIST AIRMASS WILL ONCE AGAIN EXIST OVER WESTERN AND CENTRAL WYOMING...INCREASING THE POTENTIAL FOR VERY HEAVY RAIN PRODUCING THUNDERSTORMS WITH SOME LOCALIZED FLASH FLOODING POSSIBLE. OTHERWISE...FREQUENT LIGHTNING AND WIND GUSTS TO 35 MPH CAN BE EXPECTED. THE GREATEST POTENTIAL FOR FLASH FLOODING WILL BE THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES...LANDER FOOTHILLS...WIND RIVER MOUNTAINS...BIG HORN MOUNTAINS...GREEN AND RATTLESNAKE MOUNTAINS AND CASPER MOUNTAIN. A FLASH FLOOD WATCH IS IN EFFECT FOR THESE AREAS THROUGH MIDNIGHT TONIGHT. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY DRIER AIR WILL BEGIN TO MOVE INTO WYOMING FRIDAY...DECREASING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. ISOLATED TO SCATTERED ACTIVITY IS EXPECTED FRIDAY...THEN BECOMING MAINLY ISOLATED OVER THE WEEKEND. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ASKED TO REPORT ANY FLOODING TODAY AND TONIGHT. THANK YOU. TRIW
The Riverton/Lander radar (KRIW), 25 km away, was scanning. The volume nearest the first event began at 18:16 UTC.
2 funnel cloud. Local standard time, as filed.
Motorists on State Highway 789 and a citizen in Ethete reported a funnel cloud west of the highway between Hudson and Lander.
The Johnson County Sheriff's Office reported a funnel cloud near Interstate 90 between Buffalo and Lake DeSmet.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2007Every state in 2007This day in weather historyWarnings in Wyoming, July 2007
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: 38057, 38058.