The Antelope Wildfire was first spotted on Tuesday afternoon, September 14, following a lightning strike which ignited an area of grass and sage on the northeast slope of Mount Washburn in Yellowstone National Park. Unseasonably warm temperatures coupled with dry and windy conditions doubled the size of the fire on Sunday, September 19.
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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 Antelope Wildfire was first spotted on Tuesday afternoon, September 14, following a lightning strike which ignited an area of grass and sage on the northeast slope of Mount Washburn in Yellowstone National Park. Unseasonably warm temperatures coupled with dry and windy conditions doubled the size of the fire on Sunday, September 19. The northwest corner of the fire initially threatened the Tower Fall area but no closures were needed. Over the course of the next week, however, the Grand Loop Road was closed in the vicinity of Tower Fall due to the wildfire. Fire growth was consistent over the next week. A ridge of high pressure over the Great Basin allowed for near-record and record warmth from September 25-28. On Tuesday afternoon, September 28, the fire surged across the Yellowstone River and up a west-facing mountain slope and boosted the fire's size by 1,300 acres. The wildfire was responsible for scorching nearly 4,100 acres by the end of September. More information on the conclusion of this wildfire is contained in the October 2010 Storm Data publication.
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 Sep 14, 2:14 AM MST, 4 hours 46 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 314 AM MDT TUE SEP 14 2010 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT TROUGH MOVING THROUGH THE COASTAL WEST THIS MORNING WITH A SHORTWAVE LIFTING NORTHEAST OVER SOUTH AND EAST IDAHO THIS MORNING. SOME MID AND HIGH CLOUDS SPREADING ACROSS MUCH OF THE CWA AHEAD OF THE WAVE. SOME LIGHT SHOWERS ARE POSSIBLE OVER THE NORTHWEST THIS MORNING...BEFORE THE WAVE LIFTS INTO MONTANA. WILL THEN SEE CLEARING SKIES BEHIND THE WAVE. NEXT WAVE MOVING TOWARDS THE LAX COAST THIS MORNING. IT RAPIDLY MOVES ACROSS THE GREAT BASIN THIS MORNING AND INTO NORTHERN UTAH AND EASTERN IDAHO BY LATE THIS AFTERNOON. IT WILL SPREAD INCREASING MID AND UPPER LEVEL MOISTURE OVER WESTERN AND CENTRAL WYOMING. SOME ISOLATED TO LOW SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE...MAINLY OVER THE WEST AND NORTH THIS AFTERNOON. THIS WAVE WILL ALSO ACCOMPANY THE MAIN TROUGH. SHOWER AND THUNDERSTORM COVERAGE INCREASES DURING THE EVENING AND INTO THE EARLY MORNING. THE SHOWERS WILL BEGIN TO DIMINISH OVER THE WEST AFTER MIDNIGHT...CONTINUING OVER THE BIGHORNS AND THE NORTHERN BASINS AND JOHNSON COUNTY. THE TROUGH MOVES THROUGH THE AREA BY 18Z WEDNESDAY MORNING...WITH SOME LINGERING SHOWERS PERSISTING OVER THE NORTH BEHIND IT IN THE AFTERNOON AND EARLY EVENING. A COLD FRONT MOVES THROUGH THE NORTH AND WEST TUESDAY EVENING AND INTO THE CENTRAL AND WEST AFTER MIDNIGHT. A ZONAL WEST FLOW BUILDS IN BEHIND THE TROUGH WITH AN UPPER LOW ANCHORED WELL OFF THE BRITISH COLUMBIA COAST. SEVERAL WEAK SHORTWAVES SHEAR OFF FROM THE LOW INTO THE ZONAL FLOW. MOISTURE ACCOMPANIES THESE WAVES AS THEY TRAVERSE MONTANA CLIPPING NORTHERN WYOMING WITH ISOLATED SHOWERS AND THUNDERSTORMS POSSIBLE THURSDAY AND THURSDAY NIGHT. TEMPERATURES REMAIN MILD TODAY...COOL OFF WEDNESDAY...THEN BEGIN TO REBOUND THURSDAY. .LONG TERM...FRIDAY THROUGH TUESDAY SHALLOW MODIFIED ARCTIC FRONT MEANDERS NEAR THE MONTANA/WYOMING BORDER FRIDAY AND THROUGH THE WEEKEND WITH SOME LOW CLOUDS AND CHANCES FOR LIGHT PRECIPITATION NORTH OF THE FRONT...AND MILD AND DRY WEATHER SOUTH OF THE FRONT. A COUPLE OF UPPER LEVEL SHORTWAVES AND ASSOCIATED COLD FRONTS WILL BRING MORE UNSETTLED WEATHER MONDAY AND TUESDAY. MEDIUM-RANGE MODELS IN GOOD OVERALL AGREEMENT TRANSITIONING REX-BLOCK OVER GULF OF ALASKA/NE PACIFIC TO MORE OF AN OMEGA BLOCK BY FRIDAY...AND THEN TO HIGH AMPLITUDE RIDGE OVER ALASKA UNDERCUT BY PACIFIC ENERGY EARLY NEXT WEEK. FURTHER DOWNSTREAM...UPPER LOW OVER THE NW PASSAGES EARLY THIS MORNING PLUNGES SOUTH ACROSS CENTRAL CANADA BEFORE TAKING A TURN EAST TOWARD HUDSON BAY FRIDAY. SHALLOW MODIFIED ARCTIC AIRMASS EXPECTED TO PLUNGE INTO NORTHERN PLAINS...BACKING INTO NORTHEAST WYOMING FRIDAY. THE FRONT WILL REMAIN NEARLY STATIONARY ACROSS THE NORTH AND EAST THROUGH THE WEEKEND WITH THE COLDEST DEEPEST AIR EXPECTED FURTHER NORTH AND EAST. THE SHALLOW FRONT WILL LIKELY RETREAT DURING THE AFTERNOONS AS PRESSURES FALL AND SW FLOW INCREASES ACROSS CENTRAL WYOMING AND THEN ADVANCE SOUTHWARD DURING THE EVENING. UPPER LOW OVER EASTERN PACIFIC OPENS UP AND GETS KICKED ONTO WEST COAST SUNDAY AS ENERGY BEGINS TO UNDERCUT BLOCKING UPPER HIGH OVER ALASKA. BOTH GFS AND ECMWF SHOW PACIFIC TROUGH PUSHING THROUGH GREAT BASIN AND NORTHERN ROCKIES MONDAY FOLLOWED BY KICKER COMING OUT OF THE GULF OF ALASKA INTO NORTHERN ROCKIES TUESDAY. THE PACIFIC TROUGH WILL BRING A CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS ACROSS MAINLY THE NORTH ON MONDAY FOLLOWED BY THE KICKER USHERING IN COOLER AIRMASS WITH A CHANCE OF SHOWERS ON TUESDAY. && .AVIATION... VFR CONDITIONS WILL OCCUR TODAY THROUGH THIS EVENING. SHOWERS AND THUNDERSTORMS WILL FORM IN THE WEST AFTER 19Z AND INCREASE IN AREAL COVERAGE AROUND 00Z WED. IN THE CENTRAL A FEW SHOWERS OR STORMS WILL DEVELOP AFTER 22Z WITH ADDITIONAL DEVELOPMENT AFTER 00Z WED. THE MAIN THREAT FROM THE SHOWERS AND STORMS WILL BE THE OUTFLOW WIND GUSTS...AS HIGH AS 40 KNOTS. && .FIRE WEATHER... ACTIVE WEATHER PATTERN SHAPING UP FOR TODAY AND WEDNESDAY AS A PACIFIC TROUGH APPROACHES TODAY THEN MOVES THROUGH TONIGHT INTO WEDNESDAY MORNING. SHOWERS AND THUNDERSTORMS INCREASE OVER THE WEST AND NORTH THIS AFTERNOON AND ESPECIALLY THIS EVENING. ISOLATED ACTIVITY EXPECTED OVER THE SOUTH AND CENTRAL. GUSTY WINDS TO 50 MPH AND LIGHTNING WILL BE THE MAIN THREATS WITH THE STORMS. SOME SOUTHWEST BREEZES CAN BE EXPECTED TODAY OVER THE SOUTHERN TWO THIRDS AND WESTERN MOUNTAINS. RH'S WILL DIP INTO THE LOW TEENS OVER THE LOWER ELEVATIONS OF THESE AREAS AS WELL...INCREASING THE FIRE WEATHER DANGER. A COLD FRONT MOVES ACROSS THE AREA TONIGHT SHIFTING THE WIND TO THE NORTHWEST TO NORTH. SOME LINGERING SHOWERS AND THUNDERSTORMS CAN BE EXPECTED OVER THE NORTH WEDNESDAY...DIMINISHING BY LATE AFTERNOON/EARLY EVENING. COOLER AND NOT QUITE AS LOW RH'S CAN BE EXPECTED FOR WEDNESDAY. WEST FLOW INCREASES THURSDAY WITH SEVERAL DISTURBANCES MOVING ACROSS MONTANA...WITH A FEW SHOWERS OR THUNDERSTORMS POSSIBLE OVER THE FAR NORTH. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...TWB LONG TERM...AEM AVIATION...AR FIRE WEATHER...TWB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MDT TUE SEP 14 2010 WYZ001>020-022>030-151100- 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 SEP 14 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT A LOW PRESSURE TROUGH WILL APPROACH WYOMING TODAY WITH THUNDERSTORM COVERAGE INCREASING AND SPREADING ACROSS THE WEST AND NORTH THIS AFTERNOON AND EVENING. MORE ISOLATED ACTIVITY IS EXPECTED OVER THE CENTRAL AND SOUTH. GUSTY WINDS TO 50 MPH AND LIGHTNING WILL BE THE PRIMARY THREATS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THE TROUGH MOVES THROUGH WEDNESDAY MORNING...WITH THE THUNDERSTORM THREAT BECOMING ISOLATED AND CONFINED MAINLY TO THE NORTHERN MOUNTAINS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ASKED TO REPORT WINDS OVER 40 MPH TODAY. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
1 wildfire. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2010Every state in 2010This day in weather historyWarnings in Wyoming, September 2010
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: 254218.