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