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Displaying AFOS PIL: AFDUNR Received: 2014-08-20 17:37 UTC
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491 FXUS63 KUNR 201737 AFDUNR AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1137 AM MDT WED AUG 20 2014 .UPDATE... ISSUED AT 915 AM MDT WED AUG 20 2014 CURRENT SURFACE ANALYSIS SHOWS WEAK LOW PRESSURE OVER WESTERN SD...WITH WARM FRONT EXTENDING SOUTHEAST THROUGH EASTERN NEB. A COLD FRONT ALSO EXTENDS ACROSS NORTHERN MT. UPPER LEVEL ANALYSIS SHOWS A LOW OVER THE NORTHERN GREAT LAKES REGION...WITH HIGH PRESSURE OVER THE SOUTHERN PLAINS. A LARGE SCALE TROF NOW COVERS MUCH OF THE WESTERN CONUS. SOUTHWEST FLOW IN PLACE OVER THE HIGH PLAINS IS BRINGING UNSETTLED WEATHER TO THE AREA. KUDX RADAR SHOWS ISOLATED TO SCATTERED LIGHT SHOWERS OVER MOSTLY WESTERN SD AT THIS TIME. TEMPS ARE IN THE UPPER 60S AND 70S AT THIS HOUR UNDER VARIABLY CLOUDY SKIES. THE BEST CHANCE FOR SHOWERS AND STORMS THROUGH THE AFTERNOON WILL GENERALLY BE ACROSS AREAS NORTH AND EAST OF THE BLACK HILLS...THOUGH ANY PART OF THE CWA COULD SEE A SHOWER OR THUNDERSTORM THROUGH THE DAY. THE BEST INSTABILITY IS PROGGED TO BE NEAR AND EAST OF THE SURFACE LOW...WHICH WILL REMAIN ACROSS WEST CENTRAL SD INTO THE AFTERNOON AND THEN SLOWLY MOVE EAST- SOUTHEAST OF THE AREA. THE SLIGHT RISK FOR SEVERE STORMS THIS AFTERNOON GENERALLY REMAINS NEAR AND EAST OF A LINE FROM LEMMON TO PHILIP TO MARTIN. HAVE UPDATED TO MAKE SOME ADJUSTMENTS TO POPS FOR TODAY AND TO ADD SLIGHT CHANCE POPS TO NORTHEAST WY AND THE BLACK HILLS AREA FOR TONIGHT AS ANOTHER WEAK DISTURBANCE MOVES THROUGH THESE AREAS. HAVE NOT MADE ANY ADJUSTMENTS TO HIGH TEMPS AT THIS POINT...BUT THEY MAY NEED TO BE TWEAKED A BIT IN SOME AREAS THROUGH THE DAY...DEPENDING ON EXTENT OF CLOUD AND SHOWER COVERAGE. && .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 18Z TAFS THROUGH 18Z THURSDAY) ISSUED AT 1134 AM MDT WED AUG 20 2014 SCT TSRA ARE EXPECTED TO DEVELOP THIS AFTN...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. OTHERWISE VFR CONDITIONS ARE EXPECTED. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...26 SHORT TERM...15 LONG TERM...JOHNSON AVIATION...13