FXUS63 KUNR 272157
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 PM MST FRI NOV 27 2009

.DISCUSSION...CURRENT SURFACE ANALYSIS HAS LOW OVER SOUTHWESTERN 
MB...WITH WARM FRONT OVER THE EASTERN DAKOTAS. COLD FRONT EXTENDS 
WESTWARD ACROSS NORTHERN ND AND MT. UPPER LEVEL ANALYSIS HAS 
WEAKENING RIDGE REMAINING OVER THE REGION WITH TROF MOVING ACROSS 
THE WEST COAST. SKIES ARE VARIABLY CLOUDY WITH CIRRUS...MOST OF IT 
ACROSS NORTHERN PORTIONS OF THE CWA. TEMPS ARE IN THE 50S TO MID 60S 
WITH LIGHT WINDS. 

A COOLDOWN IS ON THE WAY FOR THE WEEKEND AS COLD FRONT TO THE NORTH 
SLOWLY CROSSES THE AREA TONIGHT AND EARLY SATURDAY. UPPER LEVEL TROF 
WILL SLIDE ACROSS SATURDAY AND SATURDAY EVENING...BRINGING A FEW 
RAIN AND SNOW SHOWERS TO THE AREA. DRY WX WILL RETURN FOR SUNDAY AND 
THE FIRST PART OF NEXT WEEK...WITH TEMPS A BIT ABOVE AVERAGE 
LEVELS.

FOR TONIGHT...CLOUDS WILL INCREASE FROM NORTHWEST TO SOUTHEAST AS 
FRONT APPROACHES. TEMPS WILL DROP TO THE 20S AND 30S OVERNIGHT. 
FRONT WILL CROSS MOST OF THE AREA BY SATURDAY MORNING. 

UPPER LEVEL WAVE WILL MOVE EAST ACROSS THE AREA ON SATURDAY DURING 
THE LATE MORNING THROUGH EVENING HOURS. ATMOSPHERE WILL REMAIN 
RELATIVELY DRY SO RAIN AND SNOW SHOWER ACTIVITY SHOULD BE RATHER 
ISOLATED AND ON THE LIGHTER SIDE. PRESSURE GRADIENT WILL INCREASE 
BEHIND THE FRONT AND ALLOW FOR GUSTY NORTHWEST WINDS ACROSS MUCH OF 
THE PLAINS DURING THE LATE MORNING AND AFTERNOON HOURS. STRONGEST 
WINDS WILL BE ACROSS THE NORTHWEST AND WEST CENTRAL SD PLAINS... 
WHERE WINDS WILL GUST TO AROUND 40 MPH. HIGHS WILL MOSTLY BE IN THE 
40S. ANY LINGERING SHOWERS WILL DISSIPATE AND MOVE OUT OF THE AREA 
IN THE EVENING...WITH SOME CLEARING SKIES OVERNIGHT. SUNDAY LOOKS TO 
BE MOSTLY SUNNY WITH HIGHS IN THE 40S AND LIGHTER WINDS.    

EXTENDED...UPPER LEVEL RIDGE WILL FLATTEN ON SATURDAY AHEAD OF 
TROUGH SWINGING OUT OF SOUTHWEST CANADA. COLD FRONT WILL SWEEP 
ACROSS THE CWA EARLY ON TUESDAY AS TROUGH MOVES THROUGH EASTERN 
MONTANA. THIS WILL BRING A SLIGHT CHANCE OF SNOW SHOWERS TO 
NORTHEAST WYOMING AND FAR WESTERN SOUTH DAKOTA TUESDAY INTO TUESDAY 
NIGHT. COLD SURFACE HIGH PRESSURE WILL BUILD INTO THE CWA WEDNESDAY 
INTO THURSDAY...BRINGING MUCH COOLER TEMPERATURES TO THE AREA. AT 
THIS TIME IT IS UNCERTAIN HOW FAR WEST THE COLD AIR WILL SPREAD. 
LATEST GFS GUIDANCE SUGGESTS SLIGHTLY WARMER TEMPERATURES THAN PAST 
RUNS...WHERE THE ECMWF LOOKS COLDER. WILL KEEP HIGH TEMPS IN THE 
UPPER 20S TO LOWER 30S AT THIS TIME FOR WEDNESDAY AND THURSDAY. WEAK 
RIDGING ALOFT WILL MOVE ACROSS THE CWA ON FRIDAY AS TROUGH SWINGS 
INTO THE PACIFIC NORTHWEST AND APPROACHES THE CWA GOING INTO NEXT 
WEEKEND.  
 
&&

.AVIATION...VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

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

$$