A late afternoon thunderstorm produced strong winds in Converse County.
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 CYS wrote it up.
A late afternoon thunderstorm produced strong winds in Converse County.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Aug 7, 1:30 PM MST, 2 hours 23 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 230 PM MDT SUN AUG 7 2011 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT... SOME CONVECTION WILL MOVE ACROSS MAINLY NORTHERN AND EASTERN PARTS OF THE CWA THROUGH THIS EVENING WITH STRONGER STORMS EXPECTED TO EXIT THE CWA BY LATE THIS AFTERNOON AS SFC TROF CONTINUES TO PUSH EASTWARD. REMAINING ACTIVITY SHOULD DISSIPATE THIS EVENING. PUSH OF COOLER AIR WILL BEGIN TO MOVE INTO THE CWA MONDAY AFTERNOON AND SOME SHOWERS AND STORMS POSSIBLE IN ASSOCIATION WITH IT...MAINLY OVER THE NORTHEAST PART OF THE CWA. BETTER CHANCE FOR SOME STORMS TUESDAY AFTERNOON AND EVENING AS SFC WINDS TURN MORE EAST AND SOUTHEAST AND RATHER NARROW STRIP OF INSTABILITY SETS UP JUST EAST OF THE MTNS. TEMPERATURES ABOUT 5-8 DEGREES COOLER OVER THE PLAINS TUESDAY. .LONG TERM...WEDNESDAY THROUGH SUNDAY... MAIN FORECAST CONCERN WILL BE TEMPERATURES AND AFTERNOON CONVECTION CHANCES. ON WED LARGE SCALE UPPER FLOW PATTERN REMAINS ZONEAL WITH WEAK UPPER LEVEL SHORTWAVE ENERGY EJECTING EAST ALONG JET MAX. MEANWHILE SURFACE STATIONARY FRONT WILL REMAIN ALONG NE/WY BORDER WITH MAIN INSTABILITY AND MOISTURE AXIS IN WRN NEB PANHANDLE FOR BEST CHANCE OF TSTMS. THIS PATTERN WILL REMAIN UNTIL SHORTWAVE TROUGH IN MONTANA EJECTS EAST AND MOVES FRONTAL BOUNDARY FARTHER INTO NEBRASKA ON THURSDAY. AS SHORTWAVE TROUGH MOVES THROUGH DAKOTAS ON FRIDAY ANOTHER FRONTAL SURGE WILL SHIFT FRONT BACK WEST TOWARD LARAMIE RANGE WITH COOLER AIR SURGE AND POSSIBLE UPSLOPE SAT AND SUNDAY...ALTHOUGH SURFACE FLOW LOOKS TO BE MORE DUE SOUTH FOR MAINLY ALONG SRN MOUNTAINS. TEMPS STAY AROUND +14C TO +16C AT 700MB ON WED AND THU BEFORE DROPPING TO +7C TO +11C EAST OF LARAMIE RANGE FOR OVERALL COOLING OF TEMPS TO NEAR NORMAL OR SLIGHTLY BELOW. SUNDAY WILL RETURN TO WARMING PATTERN. HAVE ADJUSTED PCPN UP SLIGHTLY ALONG BOUNDARY IN THE EXTENDED WITH MINOR TEMPERATURE CHANGES. && .AVIATION...18Z DISCUSSION... VFR CONDITIONS WILL PREVAIL FROM NE/WY BORDER WEST AS SURFACE TROUGH MOVES EAST WITH DRY WEST TO NORTHWEST SURFACE FLOW. EXPECT POSSIBLE AFTN TSTMS WITH OCCASIONAL MVFR CIGS AND GUSTY SFC WINDS...MAINLY EAST OF CDR AFT 21Z WHERE MAIN INSTABILITY AXIS AND MOISTURE ARE PRESENT. && .FIRE WEATHER... RED FLAG CONDITIONS MET OVER EC WY THIS AFTERNOON WITH WINDS AND LOW RHS. THIS SHOULD END EARLY THIS EVENING THUS RED FLAG WARNING SHOULD EXPIRE AS EXPECTED. LESS WIND EXPECTED MONDAY THUS CONCERNS LESS. WEAK FRONT WILL DROP SOUTH ACROSS THE PLAINS LATE MONDAY WITH A LITTLE COOLER TEMPERATURES FOR TUESDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...RED FLAG WARNING UNTIL 8 PM SUNDAY FOR WYZ101-WYZ102-WYZ103. NE...NONE. && SHORT TERM/FIRE WEATHER...RE LONG TERM/AVIATION...SLA
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 307 PM MDT SUN AUG 7 2011 NEZ019-020-054-WYZ104>106-109>119-081115- SCOTTS BLUFF-BANNER-KIMBALL-FERRIS/SEMINOE/SHIRLEY MOUNTAINS- SHIRLEY BASIN-CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- CENTRAL CARBON COUNTY-NORTH SNOWY RANGE FOOTHILLS- SOUTHWEST CARBON COUNTY-SIERRA MADRE RANGE- UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE-LARAMIE VALLEY- SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 307 PM MDT SUN AUG 7 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE...EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY ISOLATED THUNDERSTORMS WILL BE POSSIBLE MONDAY THROUGH WEDNESDAY AND AGAIN ON FRIDAY AND SATURDAY. THE BEST CHANCES WILL BE CONFINED TO AREAS EAST OF THE LARAMIE RANGE. THE BEST THUNDERSTORM COVERAGE LOOKS TO BE ON TUESDAY...WHERE A FEW SEVERE THUNDERSTORMS WILL BE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE NEZ002-003-021-055-095-096-WYZ101>103-107-108-081115- DAWES-BOX BUTTE-MORRILL-CHEYENNE-NORTH SIOUX-SOUTH SIOUX- CONVERSE COUNTY LOWER ELEVATIONS-NIOBRARA COUNTY- NORTH LARAMIE RANGE-EAST PLATTE COUNTY-GOSHEN COUNTY- 307 PM MDT SUN AUG 7 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE AND EAST CENTRAL WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO MOVE ACROSS THE AREA INTO EARLY THIS EVENING BEFORE ENDING. A FEW THUNDERSTORMS MAY BECOME STRONG WITH SMALL HAIL AND GUSTY WINDS THE MAIN THREAT. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY ISOLATED THUNDERSTORMS WILL BE POSSIBLE MONDAY THROUGH WEDNESDAY AND AGAIN ON FRIDAY AND SATURDAY. THE BEST THUNDERSTORM COVERAGE LOOKS TO BE ON TUESDAY...WHERE A FEW SEVERE THUNDERSTORMS WILL BE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THIS AFTERNOON AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
155 PM MDT SUN AUG 7 2011
NEZ021-055-072045-
CHEYENNE NE-MORRILL NE-
155 PM MDT SUN AUG 7 2011
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN MORRILL AND
NORTHEASTERN CHEYENNE COUNTIES UNTIL 245 PM MDT...
AT 150 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR DALTON...OR 21 MILES NORTH OF SIDNEY...
MOVING EAST AT 20 MPH.
HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM.
LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
DALTON...
&&
LAT...LON 4133 10311 4151 10315 4161 10263 4161 10262
4140 10262 4140 10261 4135 10260
TIME...MOT...LOC 1955Z 260DEG 15KT 4144 10300
APFELPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
158 PM MDT SUN AUG 07 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0157 PM HAIL DALTON 41.41N 102.97W
08/07/2011 M0.50 INCH CHEYENNE NE TRAINED SPOTTER
MOSTLY PEA SIZED DIAMETER HAIL. ALSO MODERATE RAINFALL.
&&
MWEILANDPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
201 PM MDT SUN AUG 07 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0200 PM HAIL DALTON 41.41N 102.97W
08/07/2011 M1.00 INCH CHEYENNE NE TRAINED SPOTTER
&&
MWEILANDPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
215 PM MDT SUN AUG 07 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0213 PM HAIL DALTON 41.41N 102.97W
08/07/2011 M1.25 INCH CHEYENNE NE TRAINED SPOTTER
HAIL DIAMETER RANGED FROM ONE INCH TO ONE AND ONE QUARTER
INCHES. HAIL HAS CONTINUED SINCE 2 PM.
&&
MWEILANDSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 254 PM MDT SUN AUG 7 2011 NEZ055-072130- CHEYENNE NE- 254 PM MDT SUN AUG 7 2011 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN CHEYENNE COUNTY UNTIL 330 PM MDT... AT 250 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 12 MILES NORTH OF SUNOL...OR 19 MILES NORTHEAST OF SIDNEY...MOVING EAST AT 30 MPH. HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... MAINLY RURAL AREAS OF EXTREME NORTHEASTERN CHEYENNE COUNTY. && LAT...LON 4123 10279 4140 10274 4139 10260 4123 10260 TIME...MOT...LOC 2054Z 269DEG 28KT 4132 10266 APFEL
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
432 PM MDT SUN AUG 07 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0410 PM TSTM WND GST DEER CREEK 42.83N 105.78W
08/07/2011 M51 MPH CONVERSE WY DEPT OF HIGHWAYS
WINDS WERE SUSTAIJED AT 30 MPH.
&&
MWEILANDThe Cheyenne radar (KCYS), 189 km away, was scanning. The volume nearest the first event began at 22:53 UTC.
1 thunderstorm wind. Local standard time, as filed.
ASOS wind sensor at the Converse County Airport measured a peak wind gust of 63 mph.
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, August 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: 323472.