332 FXUS63 KUNR 181042 AFDUNR AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 342 AM MST MON FEB 18 2013 .DISCUSSION...WATER VAPOR IMAGERY SHOWS SHORTWAVE TROUGH OVER THE GREAT PLAINS...WITH THE MAIN AXIS CROSSING THE DAKOTAS. SURFACE ANALYSIS SHOWS BROAD LOW PRESSURE FROM EASTERN KANSAS TO MINNESOTA. STRONG NORTHWESTERLY WINDS ARE CONTINUING OVER THE WESTERN SOUTH DAKOTA PLAINS THIS MORNING AS A STRONG PRESSURE GRADIENT HAS SET UP OVER THE NORTHERN PLAINS. RADAR SHOWS UPSLOPE ENHANCED SNOW/GRAUPEL CONTINUING ACROSS THE NORTHERN BLACK HILLS OVERNIGHT. UPPER WAVE WILL CONTINUE TO PUSH THROUGH THE REGION TODAY. STRONG NORTHWEST WINDS WILL PERSIST ACROSS THE WESTERN SOUTH DAKOTA PLAINS THROUGH THE DAY WITH 25 TO 35 MPH WINDS AND GUSTS UP TO 50 MPH. COLD POOL ALOFT WILL KEEP STEEP LAPSE RATES ACROSS THE AREA WITH SOME SNOW SHOWERS DEVELOPING ACROSS THE PLAINS. IN ADDITION...UPSLOPE CONDITIONS WILL ALSO CONTINUE THROUGH THE DAY OVER THE NORTHERN HILLS...THOUGH ACCUMULATIONS OF LESS THAN TWO INCHES EXPECTED. UPPER RIDGING AND SURFACE HIGH PRESSURE WILL QUICKLY BUILD IN THIS AFTERNOON. AS A RESULT...WINDS WILL WEAKEN AND PRECIP WILL END BY THIS EVENING. STRONG UPPER RIDGING WILL REMAIN IN CONTROL THROUGH TUESDAY AND TUESDAY NIGHT. A STRONG...BUT STATIONARY...FRONTAL BOUNDARY WILL BRING A WIDE RANGE OF MAX TEMPS. HIGHS WILL BE IN THE TEENS OVER CENTRAL SOUTH DAKOTA...AND MID 30S OVER NORTHEAST WYOMING. THE NEXT UPPER TROUGH WILL CROSS THE GREAT BASIN EARLY WEDNESDAY...AND THE CENTRAL ROCKIES WEDNESDAY NIGHT. THIS STORM WILL STRENGTHEN AS IT PUSHES INTO THE CENTRAL PLAINS LATE WEDNESDAY NIGHT AND BRING SNOWFALL TO THE AREA...ESPECIALLY OVER SOUTH CENTRAL SD. SNOWFALL WILL THEN CONTINUE INTO THE LONG TERM...WITH SIGNIFICANT ACCUMULATIONS POSSIBLE OVER PORTIONS OF THE AREA. EXTENDED...MODELS IN VERY GOOD AGREEMENT WITH UPPER LOW MOVING FROM WESTERN KANSAS INTO EASTERN SOUTH DAKOTA ON THURSDAY...RESULTING IN WIDESPREAD SNOW FALL. STRONG ISENTROPIC LIFT DEVELOPS AHEAD OF THE UPPER THURSDAY...ESPECIALLY ACROSS SOUTH CENTRAL SOUTH DAKOTA. AS UPPER LOW TRACKS FROM NEBRASKA INTO EASTERN SOUTH DAKOTA THURSDAY EVENING...TROWAL WRAPS BACK INTO WESTERN SOUTH DAKOTA. SIGNIFICANT ACCUMULATIONS POSSIBLE ACROSS SOUTH CENTRAL SOUTH DAKOTA. UPPER LOW LINGERS ACROSS NORTH DAKOTA ON FRIDAY...WITH LIGHT SNOW/FLURRIES LINGERING THROUGH THE DAY. WEAK UPPER LEVEL RIDGE BUILDS ACROSS THE AREA FOR SATURDAY AS NEXT UPPER TROF DIGS THROUGH THE ROCKIES. THIS NEXT SYSTEM MAY BRING SOME SNOW THE AREA ON SUNDAY. && .AVIATION...12Z TAFS GUSTY NORTHWEST WINDS WILL CONTINUE THROUGH THIS AFTERNOON ON THE SOUTH DAKOTA PLAINS...WITH GUSTS OF 40-45KTS. WIDESPREAD MVFR/LCL IFR CIGS WILL PERSIST THROUGH THIS AFTERNOON. THERE WILL BE OCCASIONAL SNOW SHOWERS ACROSS THE NORTHERN BLACK HILLS...WITH ISOLATED SNOW SHOWERS ELSEWHERE. IFR VSBY WITH THE SNOW SHOWERS. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON FOR BUTTE- HAAKON-HARDING-JACKSON-MELLETTE-NORTHERN MEADE CO PLAINS- PENNINGTON CO PLAINS-PERKINS-RAPID CITY-SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-ZIEBACH. WY...NONE. && $$ SHORT TERM...13 LONG TERM....07 AVIATION...07