A line of thunderstorms moved quickly to the northeast across Yellowstone National Park downing trees in several locations.
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.
A line of thunderstorms moved quickly to the northeast across Yellowstone National Park downing trees in several locations.
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 Aug 4, 2:14 PM MST, 46 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 314 PM MDT SAT AUG 4 2007 .SHORT TERM...TONIGHT THROUGH TUESDAY ANOTHER ACTIVE EVENING IS IN STORE AS DISTURBANCE IS SPREADING SEVERAL STRONG THUNDERSTORMS ACROSS IDAHO THIS AFTERNOON. IN ADDITION...THE RIGHT ENTRANCE REGION OF A PASSING SPEED MAX MAY WELL WELL SUPPLY SOME ADDED DYNAMICS ACROSS THE NORTH THROUGH THE EVENING HOURS. A FEW OF THESE STORMS WILL LIKELY BE AT OR NEAR SEVERE LEVELS AND WITH THE MOISTURE LEVELS STILL HIGH A FEW OF THE STORMS WILL LIKELY PRODUCE VERY HEAVY RAINFALL. THE MONSOONAL PLUME WILL LIKELY LIFT NWD SOME SUNDAY BRINGING AN INCREASED CHANCE OF THUNDERSTORMS TO OUR SERN ZONES... ESPECIALLY WHEN COMBINED WITH A WEAK FRONTAL BOUNDARY WHICH IS EXPECTED TO STALL OUT IN NATRONA...ERN FREMONT AND POSSIBLY DOWN INTO ERN SWEETWATER COUNTY. SCATTERED STORMS WILL ALSO LIKELY DEVELOP ACROSS THE WEST WITH AT LEAST 20 PERCENT COVERAGE ELSEWHERE. ONCE AGAIN...ANOTHER JET STREAK MAY ADD IN RIGHT ENTRANCE REGION JET DYNAMICS LATE IN THE DAY. THE UPPER LOW CURRENTLY OFF THE NRN CA COAST IS ALSO EXPECTED TO WEAKEN AND LIFT NE TOWARDS NWRN WY LATE SUNDAY NIGHT WHICH MAY ALLOW SOME STORMS TO KEEP FIRING. ON MONDAY...THE NEXT SHORTWAVE MOVES INTO THE GREAT BASIN ON MONDAY WITH YET ANOTHER JET STREAK PUSHING ACROSS MONTANA AND NRN WYOMING. WILL HIT THE MOUNTAINS WITH CHANCE POPS FOR NOW WITH ISOLATED COVERAGE ELSEWHERE. THE NEXT BEGINS TO MOVE INTO ERN IDAHO TUESDAY MORNING WHICH WILL LIKELY INCREASE THE THREAT OF THUNDERSTORMS ON TUESDAY AND THUS WE HAVE INCREASED THE MOUNTAINS AND PARTS OF THE FAR NORTH TO CHANCE POPS WITH ISOLATED ELSEWHERE FOR NOW. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY THE SYNOPTIC PATTERN THROUGH THE LONG TERM WILL CHANGE LITTLE...WITH A MEAN TROUGH ACROSS THE WEST COAST...AND A RIDGE ACROSS THE CENTRAL AND SOUTHEAST U.S. EARLY IN THE EXTENDED...TUESDAY AND WEDNESDAY...THE AREA WILL HAVE THE BEST SHOTS AT GETTING SOME AFTERNOON AND EVENING CONVECTION...AS DISTURBANCES MOVE ACROSS THE AREA IN THE WEST/SOUTHWEST FLOW. THESE DISTURBANCES COULD BE ENHANCED BY SOME WEAK SHORTWAVE TROUGHS MOVING ACROSS SOUTHERN CANADA. THURSDAY THROUGH SATURDAY...MEDIUM RANGE MODELS INDICATE UPPER RIDGING BUILDING WESTWARD AND ENCOMPASSING THE EASTERN 2/3 OF THE COUNTRY. IN ADDITION...MODELS INDICATE DRY AIR WORKING INTO THE AREA FROM THE SOUTHWEST...WHICH SUGGESTS CONVECTION WILL BE HARD TO COME BY. HOWEVER...WILL KEEP ISOLATED AFTERNOON AND EVENING CONVECTION GOING IN FAVORED SOUTHWEST FLOW AREAS DURING THIS TIME FRAME. TEMPERATURES IN THE EXTENDED ARE EXPECTED TO BE SLIGHTLY ABOVE AVERAGE. && .AVIATION... SHOWERS AND THUNDERSTORMS WILL BE FOUND ACROSS WESTERN WYOMING THROUGH 06Z TONIGHT...AND WILL IMPACT THE KJAC AIRPORT ALONG WITH ALL ROUTES INTO AND OUT OF KJAC. STRONGER STORMS THIS AFTERNOON WILL CREATE AREAS OF IFR CONDITIONS DUE TO HEAVY RAIN. ALSO POSSIBLE WITH THESE STORMS WILL BE GUSTY AND ERRATIC WINDS...LIGHTNING...AND SMALL HAIL. WHILE THE STRONGER OF STORMS THIS AFTERNOON IS EXPECTED TO BE ACROSS NORTHWESTERN WYOMING...ISOLATED ACTIVITY IS ANTICIPATED ELSEWHERE. ISOLATED SHOWERS AND THUNDERSTORMS WILL BE CONTINUE AFTER 06Z TONIGHT. EXPECT GENERALLY VFR CONDITIONS OUTSIDE OF SHOWER ENVIRONMENTS...WITH IFR CONDITIONS POSSIBLE IN SHOWER AND STORM ACTIVITY. && .FIRE WEATHER... STRONG THUNDERSTORMS ARE QUITE POSSIBLE INTO THE EVENING HOURS ACROSS PARTS OF THE AREA...MAINLY THE WESTERN AND NORTHERN SECTIONS. THE STRONGEST STORMS COULD PRODUCE WIND GUSTS OF 40 TO 50 MPH WITH LOCALIZED HIGHER GUSTS ALONG WITH SMALL HAIL. ISOLATED STORMS MAY LINGER OVERNIGHT. ON SUNDAY...THE MONSOONAL MOISTURE WILL EDGE NORTHWARD AGAIN INTO THE RED DESERT AND GREEN MOUNTAIN/RATTLESNAKE RANGE AREA INCREASING THE CHANCE OF THUNDERSTORMS THERE. IN ADDITION...A WEAK FRONTAL BOUNDARY WILL PUSH SOUTH INTO NATRONA...EASTERN FREMONT AND EASTERN SWEETWATER COUNTIES...ALSO ASSISTING WITH AFTERNOON CONVECTION. SCATTERED AFTERNOON AND EVENING THUNDERSTORMS WILL ALSO PREVAIL ACROSS THE WEST AGAIN WITH WIDELY SCATTERED STORMS ELSEWHERE. ON MONDAY... SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS WILL PREVAIL IN THE MOUNTAINS WITH GENERALLY 10-20 PERCENT COVERAGE ELSEWHERE. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...SKRBAC LONG TERM...WM AVIATION...BRANHAM FIRE WEATHER...SKRBAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 341 PM MDT SAT AUG 4 2007 WYZ001>020-022>030-051100- 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- 341 PM MDT SAT AUG 4 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT A FEW THUNDERSTORMS WITH WIND GUSTS TO 50 MPH AND DANGEROUS LIGHTNING IS EXPECTED ACROSS WESTERN AND CENTRAL WYOMING THROUGH THE EVENING HOURS. THE HIGHEST LIKELIHOOD OF THESE STORMS WILL AROUND THE TETONS...YELLOWSTONE NATIONAL PARK...THE ABSAROKA MOUNTAINS...THE NORTHERN PORTIONS OF THE BIG HORN BASIN AND POSSIBLY THE BIG HORN MOUNTAINS. IN ADDITION...ISOLATED STORMS WITH VERY HEAVY RAIN ARE POSSIBLE THROUGH THIS EVENING WHICH MAY CAUSE FLOODING PROBLEMS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THE MONSOONAL MOISTURE WILL INCREASE ACROSS THE RED DESERT AND UP TOWARDS CASPER SUNDAY INCREASING THE CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS. A FEW OF THESE STORMS MAY PRODUCE HEAVY RAINFALL. SCATTERED THUNDERSTORMS ARE ALSO EXPECTED ACROSS WESTERN WYOMING. A FEW OF THESE STORMS MAY PRODUCE STRONG WIND GUSTS OVER 40 MPH AND LOCALLY HEAVY RAIN. SCATTERED MOUNTAIN THUNDERSTORMS ARE EXPECTED THROUGH AT LEAST TUESDAY WITH ISOLATED THUNDERSTORMS ELSEWHERE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ASKED TO REPORT ANY STRONG WIND GUSTS OVER 40 MPH...ANY HAIL...HEAVY RAINFALL AND ANY FLOODING THIS AFTERNOON AND TONIGHT. TRIW
The Pocatello radar (KSFX), 198 km away, was scanning. The volume nearest the first event began at 22:01 UTC.
4 thunderstorm wind. Local standard time, as filed.
At least 12 trees were downed between the South Entrance and Grant Village along the South Entrance Road. Park Service personnel estimated wind of 60 mph.
Burned trees within the Owl Wildfire perimeter were toppled.
Several downed trees caused a power outage at Norris Junction.
Several trees downed near Canyon.
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, August 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: 45216, 45204, 45218, 45199.