Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 200859
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
259 AM MDT WED AUG 20 2014

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 218 AM MDT WED AUG 20 2014

UPPER LEVEL ANALYSIS HAS RIDGE OVER THE CENTRAL CONUS WITH LARGE
TROF ACROSS THE WESTERN CONUS. RIDGE AXIS RESIDES OVER THE DAKOTAS
WITH SOUTHWEST UPPER FLOW MOVING INTO THE AREA. SKIES ARE MOSTLY
CLOUDY ACROSS MUCH OF THE FORECAST AREA WITH SCATTERED LIGHT
SHOWERS ACROSS SOUTH CENTRAL SOUTH DAKOTA...NORTHEAST
WYOMING...AND FAR WESTERN SOUTH DAKOTA. AT THE SURFACE...LOW
PRESSURE IS LOCATED ACROSS SOUTHEAST MONTANA WITH WEAK WARM
FRONTAL BOUNDARY EXTENDING INTO WESTERN SOUTH DAKOTA. TEMPERATURES
AT 2 AM ARE IN THE 60S AND 70S...WITH GENERALLY LIGHT WINDS. THE
EXCEPTION...BREEZY SOUTHWEST WINDS ACROSS PARTS OF NORTHEAST
WYOMING JUST SOUTH OF THE SURFACE LOW.

TODAY AND TONIGHT...CHANCES FOR SHOWERS AND STORMS WILL CONTINUE
TODAY WITH BEST CHANCES ACROSS NORTHWESTERN SD AS THE MAIN UPPER
SHORTWAVE MOVES SLOWLY NORTHEAST AND EVENTUALLY INTO ND BY LATE IN
THE DAY. PCPN CHANCES WILL GENERALLY DECREASE FURTHER SOUTH AND
EAST ACROSS THE CWA. SKIES WILL BE VARIABLY CLOUDY...WITH THE MOST
CLOUDS ACROSS NORTHERN AREAS. HIGHS WILL RANGE FROM THE LOWER 80S
ACROSS NORTHWESTERN SD TO THE LOWER 90S ACROSS PORTIONS OF
SOUTHERN SD. A SURFACE TROF WILL SLOWLY MOVE ACROSS THE AREA
DURING THE DAY...SWITCHING WINDS TO THE WEST/NORTHWEST BEHIND IT.
THE FOCUS FOR POTENTIAL STRONG TO SEVERE STORMS WILL BE MAINLY
ACROSS CENTRAL SD DURING THE AFTERNOON...AHEAD OF THE TROF AND IN
REGION OF STRONGER INSTABILITY. PCPN CHANCES SHOULD TAPER OFF FROM
SOUTHWEST TO NORTHEAST DURING THE LATE AFTERNOON AND EVENING
HOURS...WITH PCPN ENDING ACROSS THE AREA AFTER MIDNIGHT. LOW
TEMPERATURES WILL BE IN THE MID 50S TO MID 60S.

THURSDAY...UPPER LEVEL FLOW REMAINS SOUTHWEST AS WEAK SURFACE HIGH
PRESSURE MOVES INTO THE DAKOTAS. WEAK SHORTWAVE ENERGY WILL LIFT
THROUGH WESTERN AND NORTHERN PORTIONS OF THE FORECAST
AREA...BRINGING ANOTHER ROUND OF SHOWERS AND STORMS TO NORTHEAST
WYOMING AND FAR WESTERN SOUTH DAKOTA. HIGH TEMPERATURES WILL CLIMB
INTO THE 80S TO NEAR 90 DEGREES...WITH SOME 70S ACROSS THE BLACK
HILLS.

&&

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 218 AM MDT WED AUG 20 2014

LARGE UPPER TROF WILL WORK THROUGH THE ROCKIES ON
FRIDAY/SATURDAY...THEN PUSH INTO THE PLAINS SUNDAY THROUGH EARLY
NEXT WEEK. TEMPS WILL GRADUALLY COOL THROUGH THE WEEKEND...WITH
SUNDAY LIKELY BEING THE COOLEST DAY IN THE EXTENDED WITH TEMPS
STRUGGLING TO GET OUT OF THE 60S IN MANY AREAS...ESPECIALLY NERN
WY/BLKHLS/NWRN SD. TEMPS WILL THEN SLOWLY MODERATE EARLY NEXT WEEK
BUT STILL REMAIN WELL BELOW AVERAGE. PCPN CHANCES WILL CONTINUE
THROUGH MOST OF THE EXTENDED PERIOD...WITH THE BEST CHANCES
OCCURRING EARLY IN THE WEEKEND.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT
ISSUED AT 218 AM MDT WED AUG 20 2014

SCT TSRA ARE EXPECTED OVER THE AREA TODAY...WITH A DECREASE IN
COVERAGE TONIGHT. THE BEST CHANCES WILL BE FROM THE BLKHLS THROUGH
NWRN SD. LOCAL IFR CIGS/VSBYS WILL OCCUR WITH THE HEAVIEST STORMS.
OUTSIDE OF STORMS...VFR CONDITIONS WILL PREVAIL.

&&

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

$$

SHORT TERM...15
LONG TERM...JOHNSON
AVIATION...JOHNSON






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