The Sheep Herder Hill Fire started on the southeast side of Casper Mountain off of Circle Drive on Sunday, September 9. The wildfire was spread rapidly east and northeast by high temperatures, strong wind, and dry fuels.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 Sheep Herder Hill Fire started on the southeast side of Casper Mountain off of Circle Drive on Sunday, September 9. The wildfire was spread rapidly east and northeast by high temperatures, strong wind, and dry fuels. The afternoon that the blaze erupted was characterized by southwest wind gusting 30 to 40 mph and relative humidity of less than 10%. Structural damage from the fires began the first evening with at least 6 structures destroyed. By the following morning the fire had already consumed about 5,000 acres. The rapid rate of spread continued on September 10 with wind gusts again topping 30 mph for 7 hours during the afternoon and evening. A cold front swept across the fire site the evening of September 11. Cooler temperatures and a reprieve from the gusty southwest wind and low relative humidity followed frontal passage. As a result, containment of the fire began on September 12, with 100% containment achieved on the evening of September 16. A total of 15,556 acres burned. Many roads up Casper Mountain were closed for several days. Also, 38 residences, 23 outbuildings, and 5 vehicles were destroyed with an additional 2 residences damaged. In addition to property damage, the cost to fight the fire was estimated at around $4.5 to $5 million.
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 9, 2:12 PM MST, 1 hour 18 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 312 PM MDT SUN SEP 9 2012 .SHORT TERM...TONIGHT THROUGH WEDNESDAY DRY AND WINDY CONDITIONS PRESENT ACROSS MUCH OF THE AREA THIS AFTERNOON. SEVERAL LOCATIONS ARE EXPERIENCING CRITICAL FIRE WEATHER CONDITIONS...WITH NUMEROUS LOCATIONS EXPECTED TO FOLLOW SUIT THROUGH THE EVENING. HUMIDITY IS EXPECTED TO RECOVER WITH LOSS OF DAYLIGHT...AND WIND IS EXPECTED TO WEAKEN THROUGH THE LATE EVENING HOURS. A SURGE OF MONSOONAL MOISTURE IS STILL ANTICIPATED ACROSS SOUTHWEST WYOMING FOR MONDAY...THOUGH MODELS HAVE SIGNIFICANTLY WEAKENED THE AMOUNT OF PRECIPITATION ASSOCIATED WITH THIS SURGE. WITH WEAKENED PRECIPITATION EXPECTED...INCLUDED ISOLATED DRY THUNDERSTORMS ACROSS ALL AREAS ANTICIPATING SHOWER ACTIVITY. THIS ALSO GOES ALONG WELL WITH THE CONTINUED RED FLAG WARNING FOR AREAS OF WESTERN AND SOUTHERN WYOMING FROM MONDAY AFTERNOON THROUGH MONDAY EVENING. CONDITIONS AGAIN EXPECTED TO IMPROVE LATE MONDAY EVENING ACROSS IMPACTED AREAS. TUESDAY MAY ALSO SEE INCREASE FIRE BEHAVIOR AS A COLD FRONT MOVES THROUGH THE AREA. A WEAKER SURGE OF MONSOONAL MOISTURE MAY GET INTO SOUTHERN WYOMING AHEAD OF THE FRONT...TO HELP GENERATE ADDITIONAL THUNDERSTORMS DURING THE AFTERNOON HOURS. OTHERWISE...THE COLD FRONT WILL RESULT IN A SHARP WIND SHIFT...WITH NEAR CRITICAL DRY AND GUSTY CONDITIONS TUESDAY AFTERNOON FOR WESTERN WYOMING. WEDNESDAY WILL SEE A DRIER NORTHWEST FLOW DEVELOPING ACROSS THE AREA. PORTIONS OF WESTERN AND SOUTHERN WYOMING MAY EXPERIENCE INCREASED AFTERNOON WIND WITH LOWERING DAYTIME HUMIDITY. THIS MAY...AGAIN...BRING CRITICAL FIRE BEHAVIOR ACROSS WESTERN WYOMING. THE REMAINDER OF THE AREA IS EXPECTED TO HAVE LIGHT WIND THROUGH WEDNESDAY AFTERNOON. ALL AREAS OF CENTRAL AND WESTERN WYOMING WITH INCREASED FIRE CONCERNS WILL CONTINUE TO BE MONITORED. PLEASE CHECK OUR FIRE WEATHER PRODUCTS OFTEN FOR UPDATES. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY A SHORTWAVE TROUGH MOVING THROUGH THE AREA WEDNESDAY NIGHT WILL BE MOSTLY MOISTURE STARVED SO WIDESPREAD SHOWER ACTIVITY IS UNLIKELY. A FEW SHOWERS ARE POSSIBLE OVER NATRONA COUNTY IN THE MOIST AIR AHEAD OF THE WAVE INTO EARLY THURSDAY. OTHERWISE...THE EXTENDED FORECAST PERIOD WILL BE MAINLY DRY AS HIGH PRESSURE BUILDS OVER THE WESTERN CONUS. COOL AND DRY CONDITIONS WILL PREVAIL THURSDAY WITH HIGH TEMPERATURES STRUGGLING TO REACH 70 OVER MOST OF THE AREA. FRIDAY WILL SEE A RETURN OF WARMER TEMPERATURES AS THE RIDGE TAKES HOLD. WARMING TEMPERATURES AREA EXPECTED THROUGH SATURDAY WHEN THE RIDGE BEGINS TO FLATTEN UNDER THE INFLUENCE OF THE NEST LARGE UPPER TROUGH. MODELS DISAGREE ON THE STRENGTH AND LOCATION OF THE TROUGH WITH THE ECMWF DEVELOPING THE DEEPEST TROUGH WHICH WOULD BRING WINDY CONDITIONS AND PRECIPITATION FOR SUNDAY. LOW CONFIDENCE IN THE EVOLUTION ANS IMPACTS ON SUNDAYS WEATHER BUT HAVE GONE WITH ISOLATED SHOWERS AND THUNDERSTORMS IN THE WEST AND COOLER CONDITIONS FOR NOW. && .AVIATION.../00Z ISSUANCE/ VFR CONDITIONS WILL PREVAIL ACROSS MUCH OF THE AREA THROUGH 18Z MONDAY. A COLD FRONT WILL MOVE INTO FAR WESTERN WYOMING AFTER 21Z WITH SOME LIGHT SHOWER ACTIVITY BEHIND IT. CLOUDS WILL INCREASE ACROSS WESTERN WYOMING BEHIND THE FRONT BUT VFR CIGS WILL REMAIN. SMOKE FROM WILDFIRES WILL CAUSE MVFR VSBY AT TIMES TO AREAS OF WESTERN AND NORTHWESTERN WYOMING INCLUDING KJAC. THUNDERSTORM ACTIVITY WILL INCREASE OVER SOUTHERN AND WESTERN WYOMING WITH ISOLATED STORMS OVER THE MOUNTAINS ELSEWHERE AFTER 18Z WITH A FEW STORMS POSSIBLE IN THE WEST A BIT EARLIER. LOCAL MVFR CONDITIONS AND GUSTY WIND TO 40KT CAN BE EXPECTED AROUND ANY STORMS THAT DO FORM. && .FIRE WEATHER... MUCH OF THE AREA WILL CONTINUE TO EXPERIENCE...OR DEVELOP CRITICAL FIRE WEATHER BEHAVIOR THROUGH THIS AFTERNOON. CONDITIONS WILL PERSIST INTO THE EVENING HOURS BEFORE WEAKENING. MONSOONAL MOISTURE WILL BRING SOME SHOWER ACTIVITY ACROSS MUCH OF THE AREA MONDAY...WITH THE POTENTIAL FOR DRY THUNDERSTORMS IN THE AFTERNOON...AND INTO THE EARLY EVENING. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA MONDAY NIGHT AND THROUGH TUESDAY MORNING. SOME MOISTURE MAY BE PRESENT ACROSS SOUTHERN WYOMING ALONG WITH THE FRONTAL PASSAGE TO BRING ANOTHER ROUND OF POTENTIALLY DRY THUNDERSTORMS ACROSS THE AREA. MODELS HAVE ALSO BEGUN TO HINT AT INCREASED AFTERNOON WIND ACROSS WESTERN WYOMING ON WEDNESDAY...WITH DRY CONDITIONS EXPECTED. ALL SCENARIOS WILL CONTINUE TO BE MONITORED. PLEASE CONTINUE TO CHECK OUR FIRE WEATHER PRODUCTS FOR THE MOST UP TO DATE INFORMATION. && .RIW WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 9 PM MDT MONDAY WYZ277-279>281-285>289-300-414>416. RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING WYZ140-283. FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING WYZ275-276-278. && SHORT TERM...BRANHAM LONG TERM...BERC AVIATION...BERC FIRE WEATHER...BRANHAM
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 320 PM MDT SUN SEP 9 2012 WYZ001>020-022>030-101100- 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- 320 PM MDT SUN SEP 9 2012 ...RED FLAG WARNINGS FOR MUCH OF WEST AND CENTRAL WYOMING THROUGH 9 PM MONDAY... ...FIRE WEATHER WATCH FOR UPPER GREEN RIVER BASIN AND NORTHERN BIG HORN BASIN MONDAY AFTERNOON AND EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT VERY DRY...WARM AND BREEZY CONDITIONS WILL RESULT IN EXTREME FIRE BEHAVIOR AND EXPLOSIVE FIRE GROWTH ACROSS PORTIONS OF WEST AND CENTRAL WYOMING THROUGH THIS EVENING. PLEASE SEE RED FLAG WARNING PRODUCT FOR MORE INFORMATION. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY MONDAY...ISOLATED TO LOCALLY SCATTERED THUNDERSTORMS ARE EXPECTED WITH STORMS MOST NUMEROUS ACROSS THE SOUTHWEST. THE COMBINATION OF THE POTENTIAL FOR LIGHTNING TO IGNITE NEW FIRES ALONG WITH BREEZY TO WINDY CONDITIONS WILL RESULT IN CONTINUED CRITICAL FIRE WEATHER CONDITIONS ACROSS THE SOUTH AND WEST CENTRAL. CONTINUED VERY DRY... WARM AND BREEZY TO WINDY CONDITIONS WILL RESULT IN CRITICAL FIRE WEATHER CONDITIONS ACROSS THE NORTH CENTRAL AND EAST. PLEASE SEE RED FLAG WARNING AND FIRE WEATHER WATCH PRODUCTS FOR MORE INFORMATION. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. 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 2012Every state in 2012This day in weather historyWarnings in Wyoming, September 2012
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: 411972.