FXUS63 KUNR 110343
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
845 PM MST THU DEC 10 2009
.DISCUSSION...AT 03Z SFC MAP SHOWS WK RIDGE OF HIGH PRES ACRS
WRN NEB/NERN WY...ALOFT BROAD NW FLOW CONTS ACRS THE NRN PLAINS.
SCT-BKN MID LEVEL CLOUDS MVG ACRS MT/ND AND INTO NERN WY AND
WRN SD. OTHER THAN A FEW MID CLOUDS SHOULD BE A QUITE NIGHT.
CURRENT FCST IN GOOD SHAPE AND WILL NOT UPDATE.
PREVIOUS FORECAST DISCUSSION:(230PM MST)...
MODELS CONTINUE TO SHOW THE CYCLONIC FLOW ALOFT TRANSITIONING INTO
A MORE ZONAL TYPE PATTERN HEADING INTO THE WEEKEND. WARMER AIR WILL
CONTINUE TO ADVECT OVERNIGHT TONIGHT INTO FRIDAY WITH HIGHS REACHING
THE 20S ACROSS NORTHWEST AND CENTRAL SOUTH DAKOTA...AND LOWER 30S
ACROSS SOUTHWEST SOUTH DAKOTA THROUGH THE BLACK HILLS INTO NORTHEAST
WYOMING. MOSTLY SUNNY TO PARTLY CLOUDY SKIES ARE FORECAST FOR THE
AREA. ANOTHER QUIET DAY IS EXPECTED SATURDAY...WITH TEMPERATURES
WARMER THAN FRIDAY. MODELS SHOW A SHORTWAVE OVER IDAHO MOVING
EASTWARD WITHIN THE ZONAL FLOW...WITH A DEVELOPING UPPER LOW OVER
THE NORTHWEST PACIFIC COAST. THE WAVE IS PROGGED TO APPROACH THE CWA
LATE SATURDAY...POSSIBLY BRINGING SOME SNOW TO NORTHEASTERN WYOMING
AND FAR WESTERN SOUTH DAKOTA. IT IS POSSIBLE THE LOWER LEVELS WILL
BE TOO DRY TO SUPPORT ANY PRECIP...BUT WILL LEAVE IN THE SLIGHT
CHANCE POPS FOR NOW IN CASE TRENDS SUGGEST A FASTER WAVE OR BETTER
AVAILABLE MOISTURE. HAVE REMOVED ALL POPS FOR EARLIER SATURDAY
HOWEVER. THE BETTER CHANCES FOR PRECIP WILL BE AFTER SATURDAY NIGHT
IN THE LONG TERM FORECAST.
EXTENDED...NEXT SHOT OF ARCTIC AIR IS SET TO ARRIVE LATE SUNDAY...
WITH ALL THE 12Z GUIDANCE IN GOOD AGREEMENT. EXPECT THERE WILL BE
ENOUGH MOISTURE TO COMBINE WITH THE INTENSE COLD ADVECTION TO
PRODUCE SOME LIGHT SNOW ACROSS THE AREA SO HAVE BOOSTED POPS FOR
SUNDAY NIGHT INTO MONDAY. THIS SHOT OF COLD AIR SHOULD BE SHORT
LIVED...THOUGH...AS UPR RIDGE WILL BE QUICK TO REBUILD INTO THE NRN
ROCKIES. TEMPS COULD WARM TO ABOVE AVERAGE READINGS TOWARDS THE
MIDDLE/END OF NEXT WEEK.
&&
.AVIATION...VFR CONDS WILL CONT THRU FORECAST PERIOD.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
