Hail and Damaging Winds in Wyoming, August 17, 2015

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
524 PM MDT MON AUG 17 2015

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 315 PM MDT MON AUG 17 2015

CURRENT SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY WELL SOUTH AND
EAST OF THE REGION...WITH HIGH PRESSURE CENTERED OVER NORTHERN ND
AND SOUTHERN SK. UPPER LEVEL ANALYSIS SHOWS TROF OVER THE UPPER
MIDWEST...WITH ZONAL FLOW OVER THE NORTHERN PLAINS. A STRONG
SHORTWAVE LOCATED OVER WESTERN INTO CENTRAL MT IS QUICKLY DIGGING
EAST-SOUTHEASTWARD ACROSS THE NORTHERN ROCKIES. REGIONAL RADARS
SHOW A FEW SHOWERS FROM THE BLACK HILLS INTO CENTRAL SD...WITH
MORE WIDESPREAD AND HEAVIER SHOWER AND THUNDERSTORM ACTIVITY OVER
CENTRAL AND EASTERN MT INTO PORTIONS OF NORTHERN WY. TEMPS REMAIN
QUITE COOL WITH LOTS OF CLOUD COVER...60S AND LOWER 70S ACROSS THE
PLAINS...50S OVER THE BLACK HILLS.

THE SHORTWAVE TO THE WEST WILL MOVE RELATIVELY QUICKLY ACROSS THE
REGION TONIGHT INTO TUESDAY...WITH WIDESPREAD SHOWERS AND EMBEDDED
THUNDERSTORMS DEVELOPING. VARIOUS 12Z MODEL RUNS STILL SHOW RAINFALL
AMOUNTS OF 1 TO 2 INCHES ARE LIKELY ACROSS A GOOD PORTION OF THE
FORECAST AREA. THE EXCEPTION MAY BE ACROSS PARTS OF NORTHEAST WY AND
FAR NORTHWEST SD...WHERE AMOUNTS WILL GENERALLY BE AT LEAST A BIT
LOWER. THERE ARE SOME DIFFERENCES ON TIMING AND EVOLUTION OF UPPER
LOW AS IT CROSSES...BUT THEY ARE RELATIVELY MINOR AT THIS POINT.

FOR LATE THIS AFTERNOON INTO TONIGHT...SHORTWAVE TO THE WEST WILL
BRING INCREASING COVERAGE OF SHOWERS AND STORMS FROM NORTHEAST WY
INTO WESTERN SD. THE BEST INSTABILITY IS PROGGED TO BE FROM
NORTHEAST WY INTO SOUTHWEST SD LATE THIS AFTERNOON AND EARLY
EVENING...WHERE THE MOST BREAKS IN THE CLOUD COVER WILL BE...WITH
CAPE VALUES TAPERING OFF TO THE NORTH AND EAST OF THESE AREAS. SHEAR
WILL BE MOST FAVORABLE IN THIS AREA AS WELL FOR POTENTIALLY ROTATING
STORMS. STRONG TO SEVERE STORMS WITH HAIL AND GUSTY WINDS WILL BE
POSSIBLE OVER NORTHEAST WY AND POSSIBLY INTO FAR SOUTHWEST SD LATE
THIS AFTERNOON AND EARLY EVENING. OTHERWISE...SHOWERS AND ISOLATED
STORMS WILL OVERSPREAD THE FORECAST AREA...ESPECIALLY LATER THIS
EVENING AND OVERNIGHT. DEVELOPING SURFACE LOW TO THE SOUTH OF THE
REGION WILL RESULT IN INCREASING EAST TO NORTHEAST UPSLOPE FLOW AND
LIKELY BRING SOME ENHANCED AREAS OF RAINFALL OVER THE NORTHERN AND
EASTERN SLOPES OF THE BLACK HILLS AREA AND THE ADJACENT PLAINS
OVERNIGHT.

BULK OF HEAVIER RAINFALL WILL BE EAST OF THE BLACK HILLS TUESDAY
MORNING AS THE SHORTWAVE BEGINS TO CLOSE OFF OVER WESTERN INTO
CENTRAL SD. WILL TAPER OFF POPS A BIT FROM THE BLACK HILLS WESTWARD
LATE TONIGHT AND TUESDAY MORNING. HEAVIER RAINFALL SHOULD BE EAST OF
THE CWA BY EARLY TUESDAY AFTERNOON. HIGHS ON TUESDAY WILL ONLY BE IN
THE LOW TO MID 60S ACROSS THE PLAINS...50S OVER THE BLACK HILLS. AS
THE DEVELOPING UPPER LOW WRAPS UP TO THE EAST...ENERGY ALOFT WILL
SLIDE SOUTH ON THE BACK SIDE OF THE SYSTEM...WITH CHANCES FOR
SHOWERS CONTINUING INTO TUESDAY NIGHT ACROSS MUCH OF THE AREA. MOST
OF THE ACTIVITY WILL END OVERNIGHT WITH PARTIAL CLEARING. CHILLY
TEMPS EXPECTED EARLY WEDNESDAY MORNING...WITH SOME 30S OVER THE
BLACK HILLS.

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 315 PM MDT MON AUG 17 2015

UPPER LOW MOVES TO WESTERN GREAT LAKES WEDNESDAY...WITH
DRIER NORTHWEST FLOW ACROSS THE NORTHERN PLAINS. MARGINAL
INSTABILITY/MOISTURE FOR A FEW SHOWERS OVER THE BLACK HILLS
WEDNESDAY AFTERNOON. FLOW BECOMES ZONAL FOR THU-FRI...WITH DRY
WEATHER AND WARMER TEMPERATURES. NEXT UPPER TROF MOVES INTO THE NRN
PLAINS EARLY IN THE WEEKEND FOR AN INCREASING CHANCE OF
PCPN...ESPECIALLY SATURDAY...AND COOLER TEMPS. DRY WEATHER AND
WARMER TEMPS RETURN EARLY NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 515 PM MDT MON AUG 17 2015

SCT SHRA/TSRA WILL SPREAD EAST THIS EVENING WITH DETERIORATING
FLIGHT CONDS BEHIND A STRONG COLD FRONT. WDSPRD RAIN IS THEN
EXPECTED TONIGHT WITH WDSPRD IFR CONDS...AREAS OF LIFR POSSIBLE
TOO. GUSTY WINDS CAN BE EXPECTED BEHIND THE COLD FRONT...ESP ON
THE SD PLAINS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

SHORT TERM...26
LONG TERM...JOHNSON
AVIATION...JC

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
1045 AM MDT MON AUG 17 2015

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-181300-
HARDING-PERKINS-BUTTE-NORTHERN MEADE CO PLAINS-ZIEBACH-
NORTHERN BLACK HILLS-NORTHERN FOOT HILLS-RAPID CITY-
SOUTHERN FOOT HILLS-CENTRAL BLACK HILLS-SOUTHERN BLACK HILLS-
CUSTER CO PLAINS-PENNINGTON CO PLAINS-HAAKON-FALL RIVER-SHANNON-
JACKSON-BENNETT-MELLETTE-TODD-TRIPP-STURGIS/PIEDMONT FOOT HILLS-
SOUTHERN MEADE CO PLAINS-HERMOSA FOOT HILLS-NORTHERN CAMPBELL-
SOUTHERN CAMPBELL-WESTERN CROOK-WYOMING BLACK HILLS-WESTON-
NORTHEASTERN CROOK-
1045 AM MDT MON AUG 17 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TODAY AND TONIGHT

A STRONG UPPER LEVEL SYSTEM WILL BRING INCREASING CHANCES FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON AND ESPECIALLY TONIGHT. THERE IS
A SLIGHT RISK FOR SEVERE THUNDERSTORMS ACROSS MUCH OF NORTHEAST
WYOMING THIS AFTERNOON AND EARLY EVENING. LARGE HAIL AND STRONG
WIND GUSTS WILL BE THE MAIN THREATS WITH ANY SEVERE STORMS. A
STRONG STORM OR TWO WITH HAIL AND GUSTY WINDS IS ALSO POSSIBLE
ACROSS THE BLACK HILLS AND SOUTHWEST SOUTH DAKOTA THIS AFTERNOON
AND EVENING.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO TUESDAY...ALONG WITH
WELL BELOW AVERAGE TEMPERATURES. WIDESPREAD SEVERE WEATHER IS NOT
EXPECTED AT THIS TIME. MANY AREAS OF NORTHEAST WYOMING AND
WESTERN SOUTH DAKOTA WILL RECEIVE AN INCH OR MORE OF RAINFALL FROM
LATE TODAY THROUGH TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.

&&

STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER DETAILS OR UPDATES...
OR CHECK OUR WEB SITE AT WEATHER.GOV/RAPIDCITY

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RAPID CITY SD
602 PM MDT MON AUG 17 2015

SDZ001-012-180100-
BUTTE SD-HARDING SD-
602 PM MDT MON AUG 17 2015

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN BUTTE AND
SOUTHWESTERN HARDING COUNTIES UNTIL 700 PM MDT...

AT 601 PM MDT...DOPPLER RADAR WAS TRACKING A LINE OF STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM NEAR WEST SHORT PINES TO 11
MILES NORTHEAST OF ALZADA...AND MOVING EAST AT 25 MPH.

DIME SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
REDIG...GUSTAVE AND NORTHWESTERN BELLE FOURCHE RESERVOIR.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THESE STORMS.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.

&&

LAT...LON 4532 10313 4473 10378 4497 10407 4499 10406
      4501 10404 4530 10405 4531 10403
TIME...MOT...LOC 0001Z 286DEG 23KT 4536 10392 4511 10421

AWARD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
655 PM MDT MON AUG 17 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0645 PM     TSTM WND GST     16 WSW DOWNTOWN GILLETT 44.22N 105.81W
08/17/2015  M53 MPH          CAMPBELL           WY   DEPT OF HIGHWAYS

&&

JC