A thunderstorm produced heavy rain over portions of southern Crook County. Two and a half inches of rain fell in less than 30 minutes south of Keyhole Reservoir.
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The episode as NWS UNR wrote it up.
A thunderstorm produced heavy rain over portions of southern Crook County. Two and a half inches of rain fell in less than 30 minutes south of Keyhole Reservoir.
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 Rapid City, SD wrote its last area forecast discussion before the first event at Aug 3, 9:55 AM MST, 3 hours 5 minutes earlier.
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1055 AM MDT WED AUG 3 2011 .DISCUSSION...WATER VAPOR IMAGERY SHOWS UPPER RIDGING ACROSS THE CENTRAL CONUS WITH DEEP SOUTHWESTERLY FLOW ACROSS THE CWA. SEVERAL WAVES WERE MOVING WITHIN THE FLOW ACROSS WYOMING INTO EASTERN MONTANA. REGIONAL RADAR SHOWING A BAND OF SHOWERS AND STORMS ASSOCIATED WITH SOME OF THESE WAVES MOVING ACROSS PARTS OF NORTHEAST WYOMING INTO NORTHWEST SOUTH DAKOTA. MORE SHOWERS AND STORMS ARE EXPECTED TO DEVELOP THROUGH THE DAY AS THE WAVES IN WY APPROACH THE AREA. MODELS ARE INDICATING A GREAT DEAL OF MOISTURE ACROSS THE AREA. PWATS ARE EXPECTED TO INCREASE TO UP TO 150 TO 180 PERCENT OF NORMAL ALONG WITH GOOD MOISTURE CONVERGENCE. HAVE INCREASED POPS AND ADDED MENTION OF LOCALLY HEAVY RAINFALL THIS AFTERNOON AND EVENING. NO OTHER CHANGES NEEDED. && .PREV DISCUSSION... /ISSUED 200 AM MDT WED AUG 3 2011/ DISCUSSION...CURRENT SURFACE ANALYSIS PLACES HIGH PRESSURE OVER CENTRAL SOUTH DAKOTA/NEBRASKA WITH RETURN FLOW SETTING UP OVER NERN WYO INTO FAR WRN SD. UPPER LEVEL ANALYSIS SHOWS PERSISTENT HIGH OVER THE SRN PLAINS WITH MONSOONAL FLOW STARTING TO DEVELOP INTO OUR AREA. VARIOUS WAVES NOTED IN THE FLOW. FOR TODAY...UNSETTLED PATTERN DEVELOPS AS MONSOONAL FLOW CONTINUES TO INCREASE ACROSS THE AREA. PRIMARY WAVE TO PUSH INTO THE AREA TODAY IS CURRENTLY PUSHING TO THE EAST OF SALT LAKE SLIDING INTO SOUTHWEST WY...AND SHOULD START SLIDING INTO OUR AREA BY LATE MORNING. EXPECT CONVECTION TO DEVELOP LATE MORN INTO THE AFT WITH THIS ADVANCING WAVE. SEVERE POTENTIAL IS EXPECTED TO REMAIN MINIMAL WITH CAPE VALUES ~0.5-1.5 KJ/KG (MAINLY OVER WRN CWFA) AND MARGINAL SHEAR...THOUGH AN ISOLATED STRONG STORM OR TWO CANNOT BE RULED OUT. EXPECT STORM POTENTIAL TO CONTINUE INTO THE EVENING AS LOW LEVEL JET/THETA-E ADVECTION INCREASES OVER PTNS OF THE SODAK PLNS. ON THURSDAY...PATTERN REMAINS SIMILAR WITH MINIMAL INSTABILITY AND MARGINAL SHEAR THROUGHOUT MUCH OF THE CWFA...SO WILL CONTINUE THUNDERSTORM CHANCES WITH MINIMAL SEVERE THREAT. FOR FRIDAY...ACTIVE PATTERN CONTINUES. MODELS NOW SHOWING SFC LOW DEVELOPING OVER SERN MONTANA WITH WARM FRONT SETTING UP OVER NWRN SD BEFORE SLOWLY PUSHING EAST-SERLY IN THE LATE AFT/EVE. INSTABILITY STRENGTHENS ACROSS THE CWFA (1.5-2.5 J/KG IN EARLY AFT) WITH STRONGEST INSTABILITY NEAR THE NODAK BORDER. STRONGEST 0-6KM BULK SHEAR ALSO IS STRONGEST IN THIS AREA...WITH LOW LEVEL SHEAR INCREASING THROUGH THE DAY NE OF SFC LOW. WILL HAVE TO KEEP AN EYE ON HOW THE NEXT FEW MODEL RUNS HANDLE THIS SYSTEM AS THIS COULD BE OUR NEXT SEVERE EVENT. EXTENDED...A MOIST WEST-NORTHWEST UPPER FLOW WILL CONTINUE THRU THE EXTENDED PERIOD. PERIODIC UPPER DISTURBANCES WILL MOVE THRU THE UPPER FLOW BRINGING A DAILY CHANCE OF SHOWERS/TSTMS...MAINLY IN THE AFTERNOON AND EVENING. TEMPERATURES WILL REMAIN NEAR AVERAGE THRU THE PERIOD. && .AVIATION...SCATTERED THUNDERSTORMS ARE POSSIBLE WITH LOCAL MVFR/ IFR CONDITIONS POSSIBLE IN AND NEAR ANY THUNDERSTORMS. OTHERWISE VFR CONDITIONS ARE EXPECTED. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RAPID CITY SD 1101 AM MDT WED AUG 3 2011 SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058- 071-041300- BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON- HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK- NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS- NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY- SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS- SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP- WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH- 1101 AM MDT (1201 PM CDT) WED AUG 3 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED TODAY INTO TONIGHT WITH LOCALLY HEAVY RAINFALL POSSIBLE. A FEW STORMS MAY BECOME CAPABLE OF PRODUCING SMALL HAIL AND GUSTY WINDS...SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY CHANCES FOR THUNDERSTORMS WILL CONTINUE OVER MUCH OF THE AREA EACH DAY THROUGH EARLY NEXT WEEK. AT THIS TIME THE GREATEST CHANCE FOR SEVERE WEATHER WILL COME ON FRIDAY...PARTICULARLY TO NORTHWEST SOUTH DAKOTA...AS A LOW PRESSURE SYSTEM MOVES THROUGH THE AREA. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RAPID CITY SD 1226 PM MDT WED AUG 3 2011 WYZ054>056-058-031915- NORTHERN CAMBELL WY-SOUTHERN CAMPBELL WY-WESTERN CROOK WY-WESTON WY- 1226 PM MDT WED AUG 3 2011 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN CAMPBELL...SOUTHWESTERN CROOK AND NORTHWESTERN WESTON COUNTIES UNTIL 115 PM MDT... AT 1222 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR MOORCROFT...OR 24 MILES EAST OF DOWNTOWN GILLETTE...MOVING NORTHEAST AT 15 MPH. HAIL UP TO THE SIZE OF PENNIES IS EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... MOORCROFT... KEYHOLE RESERVOIR... PINE HAVEN... THIS INCLUDES INTERSTATE 90 BETWEEN WYOMING MILE MARKERS 146 AND 167... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. BUNKERS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RAPID CITY SD 1234 PM MDT WED AUG 3 2011 WYZ054>056-058-031930- NORTHERN CAMBELL WY-SOUTHERN CAMPBELL WY-WESTERN CROOK WY-WESTON WY- 1234 PM MDT WED AUG 3 2011 ...SIGNIFICANT WEATHER ADVISORY FOR EXTREME EASTERN CAMPBELL... SOUTHWESTERN CROOK AND NORTHWESTERN WESTON COUNTIES UNTIL 130 PM MDT... AT 1231 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR MOORCROFT...OR 25 MILES EAST OF DOWNTOWN GILLETTE...MOVING NORTHEAST AT 15 MPH. HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... MOORCROFT... KEYHOLE RESERVOIR... PINE HAVEN... THIS INCLUDES INTERSTATE 90 BETWEEN WYOMING MILE MARKERS 149 AND 164... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. BUNKERS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RAPID CITY SD 135 PM MDT WED AUG 3 2011 WYZ056-057-032030- WESTERN CROOK WY-WYOMING BLACK HILLS WY- 135 PM MDT WED AUG 3 2011 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN CROOK COUNTY UNTIL 230 PM MDT... AT 131 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 11 MILES NORTHWEST OF INYAN KARA MOUNTAIN...OR 12 MILES SOUTHWEST OF SUNDANCE...MOVING EAST AT 20 MPH. HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... SUNDANCE... INYAN KARA MOUNTAIN... MOSKEE... THIS INCLUDES INTERSTATE 90 BETWEEN WYOMING MILE MARKERS 166 AND 191... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. BUNKERS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RAPID CITY SD 137 PM MDT WED AUG 3 2011 SDZ012-025-072-073-032015- BUTTE SD-NORTHERN FOOT HILLS SD-SOUTHERN MEADE CO PLAINS SD-STURGIS/PIEDMONT FOOT HILLS SD- 137 PM MDT WED AUG 3 2011 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN LAWRENCE...WESTERN MEADE AND SOUTHERN BUTTE COUNTIES UNTIL 215 PM MDT... AT 136 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR FRUITDALE...OR 5 MILES SOUTHEAST OF DOWNTOWN BELLE FOURCHE...MOVING EAST AT 20 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... FRUITDALE... BELLE FOURCHE RESERVOIR... NISLAND... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. BUNKERS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RAPID CITY SD 154 PM MDT WED AUG 3 2011 SDZ012-025-072-073-032045- BUTTE SD-NORTHERN FOOT HILLS SD-SOUTHERN MEADE CO PLAINS SD-STURGIS/PIEDMONT FOOT HILLS SD- 154 PM MDT WED AUG 3 2011 ...SIGNIFICANT WEATHER ADVISORY FOR EXTREME NORTHEASTERN LAWRENCE... WESTERN MEADE AND SOUTHERN BUTTE COUNTIES UNTIL 245 PM MDT... AT 150 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR VALE...OR 11 MILES NORTH OF DOWNTOWN STURGIS...MOVING EAST AT 15 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... VALE... AREAS NORTH OF BEAR BUTTE STATE PARK... TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. BUNKERS
The national radar mosaic for the moment the first event began.
1 heavy rain. Local standard time, as filed.
Heavy rain briefly caused minor flooding along a 100 foot section of Wagner Road south of Interstate 90.
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: 347652.