Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 280428
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1028 PM MDT WED AUG 27 2014

.UPDATE...
ISSUED AT 601 PM MDT WED AUG 27 2014

WDSPRD SHRA/TSRA CONTINUES TO LIFT NEWD ACROSS NERN THROUGH SWRN
SD...SO HAVE RAISED POPS SIGNIFICANTLY FOR THIS EVENING THAT AREA...WHILE
ALSO EXPANDING POPS A BIT FURTHER NORTH. SOME OF THIS RAINFALL IS
VERY HEAVY.

&&

.SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT
ISSUED AT 305 PM MDT WED AUG 27 2014

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER FAR NORTHEAST
CO...WITH A NEARLY STATIONARY FRONTAL BOUNDARY FROM SOUTHERN WY TO
CENTRAL KS. UPPER LEVEL ANALYSIS SHOWS LOW PRESSURE OVER NORTHWEST
CO...WITH TROF COVERING THE ROCKIES AND MUCH OF THE HIGH PLAINS.
SKIES HAVE BECOME MOSTLY CLOUDY ACROSS MUCH OF THE AREA...EXCEPT
FOR FAR NORTHWESTERN SD. REGIONAL RADARS SHOW MAIN BAND OF SHOWERS
AND STORMS ROTATING NORTH-NORTHEAST AROUND UPPER LOW ACROSS MUCH
OF EASTERN WY...THE NEB PANHANDLE...AND INTO FAR SOUTHWESTERN SD.
SCATTERED SHOWERS AND STORMS HAVE DEVELOPED ELSEWHERE ACROSS
SOUTHWEST AND SOUTH CENTRAL SD...AS WELL AS OVER THE BLACK HILLS.
SLOW MOVING STORMS OVER WESTERN PORTIONS OF THE BLACK HILLS HAVE
PRODUCED SOME LOCALLY HEAVY RAINFALL EARLY THIS AFTERNOON.
TEMPERATURES ARE IN THE UPPER 60S AND 70S WITH SOUTHEASTERLY
WINDS.

THE GENERAL TREND FOR SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS SHOULD CONTINUE INTO TONIGHT ACROSS SOUTHERN PORTIONS
OF THE CWA AS THE UPPER LOW MOVES SLOWLY EAST INTO THE CENTRAL HIGH
PLAINS BY EARLY THURSDAY. THERE WILL BE A FAIRLY SHARP CUT-OFF TO
THE COVERAGE OF SHOWERS THROUGH THE EVENING...GENERALLY SOUTH OF
INTERSTATE 90. THE THREAT FOR SEVERE STORMS REMAINS LOW WITH MAIN
AREA OF INSTABILITY STAYING SOUTH OF THE FORECAST AREA AND WEAK
SHEAR IN PLACE. HOWEVER...THERE IS A THREAT FOR LOCALLY HEAVY
RAINFALL ACROSS SOUTHERN AREAS THIS EVENING...ESPECIALLY OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD...WHERE PRECIPITABLE WATER VALUES
WILL BE WELL ABOVE AVERAGE AND A COMPLEX OF STORMS COULD MOVE
THROUGH DURING THE EVENING. WITH A LOT OF LOW LEVEL MOISTURE AROUND
THE AREA AND LIGHT WINDS OVERNIGHT...WILL ADD AREAS OF FOG TO MUCH
OF THE WESTERN AND SOUTH CENTRAL SD PLAINS LATE TONIGHT INTO EARLY
THURSDAY.

AS THE UPPER LOW MOVES SLOWLY ACROSS THE CENTRAL HIGH PLAINS LATE
TONIGHT AND THURSDAY...CHANCES FOR SHOWERS AND STORMS SHOULD MOSTLY
BE LIMITED TO THE SOUTH CENTRAL SD AREA. WILL ADD A SLIGHT CHANCE
FOR SHOWERS AND STORMS TO THE CENTRAL AND SOUTHERN BLACK HILLS FOR
THE AFTERNOON WITH SOME LINGERING INSTABILITY AROUND POSSIBLY
PRODUCING A TERRAIN INDUCED SHOWER OR STORM. SKIES WILL BE VARIABLY
CLOUDY...WITH THE MOST SUN ACROSS NORTHERN AND WESTERN PORTIONS OF
THE CWA. WARMER AIR CAN BE EXPECTED ON THURSDAY...ESPECIALLY
ACROSS THESE NORTHERN AND WESTERN AREAS. HIGHS SHOULD RANGE FROM THE
MID 70S TO MID 80S.

CLOUDS WILL CONTINUE TO GRADUALLY DECREASE FROM NORTHWEST TO
SOUTHEAST LATE THURSDAY INTO THURSDAY NIGHT...WITH MOSTLY CLEAR
SKIES OVERNIGHT. SOME FOG COULD AGAIN BE POSSIBLE OVER THE SD PLAINS
LATE...BUT WILL TAKE A CLOSER LOOK AT THAT TOMORROW. LOWS WILL BE IN
THE 50S AND LOWER 60S WITH MOSTLY LIGHT AND VARIABLE WINDS.

&&

.LONG TERM...FRIDAY THROUGH WEDNESDAY
ISSUED AT 305 PM MDT WED AUG 27 2014

FRIDAY...A SHORTWAVE WILL MOVE ACROSS MT/ND PUSHING A COLD FRONT
SOUTH OF THE CWA AS HIGH PRESSURE BUILDS IN OVER SOUTH CENTRAL
CANADA. DEPENDING ON THE AMOUNT OF LOW LEVEL SUBSIDENCE BEHIND THE
SHORTWAVE...A NARROW BAND OF SUFFICIENT CAPE/SHEAR PRESENT FOR
POST FRONTAL ISOLATED STRONG/SEVERE STORMS ACROSS NORTHWEST HALF
OF CWA...BUT CONFIDENCE LOW. TEMPERATURES WILL BE TRICKY WITH WEAK
COOL AIR ADVECTION.

SATURDAY...ANOTHER SHORTWAVE WILL MOVE ACROSS SOUTHERN MT/NORTHERN
WY AHEAD OF LEE TROUGH...WHICH WILL DEVELOP A LOW ALONG IT IN
SOUTHEAST MT AND DRAG ANOTHER COLD FRONT THROUGH THE CWA SATURDAY
NIGHT. SUFFICIENT CAPE/SHEAR WILL BE PRESENT FOR STRONG/SEVERE
STORMS...BUT MLCIN MAY BE NOTABLE GIVEN DEVELOPING THERMAL RIDGE
AHEAD OF SHORTWAVE. TEMPERATURES WILL BE NEAR NORMAL.

HAVE ADDED/EXPANDED POPS BOTH FRIDAY/SATURDAY TO ACCOUNT FOR LATEST
THINKING.

SUNDAY THROUGH WEDNESDAY...ACTIVE PATTERN CONTINUES WITH NORTHWEST
FLOW ALOFT SUNDAY THROUGH TUESDAY...WITH A SLOW TRANSITION TO
RIDGING ACROSS THE NORTHERN PLAINS FOR THE MIDDLE OF THE WEEK.
COOLISH TEMPERATURES TO START SUNDAY BEHIND SATURDAY/S COOL
FRONT...BUT THEN WARMING BACK TO NEAR NORMAL FOR THE MIDDLE OF NEXT
WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1025 PM MDT WED AUG 27 2014

WDSPRD SHRA WILL CONTINUE TONIGHT...ESPECIALLY EAST OF THE BLKHLS
INTO CNTRL SD. LOCAL IFR VSBY IN HEAVIER -SHRA. THE PCPN WILL THEN
SHIFT EAST OF THE REGION ON THURSDAY. MVFR CIGS EXPECTED TO
REDEVELOP ON THE PLAINS OF WRN SD OVERNIGHT...WITH LCL IFR
CIGS/VSBY IN FOG. CONDITIONS WILL SLOWLY IMPROVE ON THURSDAY.

&&

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

$$

UPDATE...JOHNSON
SHORT TERM...26
LONG TERM...HELGESON
AVIATION...JOHNSON





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