000
FXUS63 KUNR 272122
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
220 PM MST MON DEC 27 2010
.DISCUSSION...A VERY PLEASANT WINTER DAY HAS UNFOLDED OVER THE
BLKHLS REGION THIS AFTERNOON. A DIFFLUENT WESTERLY FLOW ALOFT AND
ADVANCING SURFACE HIGH PRESSURE HAS DISSIPATED MOST OF THE HIGH
LEVEL MOISTURE TRYING TO ENTER THE NORTHERN PLAINS THIS AFTERNOON
LEAVING MOSTLY SUNNY SKIES FROM THE ROCKIES EASTWARD. TEMPERATURES
LEVELED OFF EARLY IN THE DAY DUE TO A LITTLE COOL ADVECTION
ALOFT...BUT THE MORNING FORECAST STILL WORKED OUT VERY WELL.
TONIGHT THROUGH TUESDAY NIGHT...
MORE OF THE SAME IS IN STORE FOR THE NEAR TERM. SEASONABLY MILD
TEMPERATURES AND FAIR SKIES WILL CONTINUE UNDER A ZONAL FLOW ALOFT
AND HIGH PRESSURE AT THE SURFACE.
WEDNESDAY AND WEDNESDAY NIGHT...
A HINT OF WHAT'S IN STORE FOR THE LAST HALF OF THE WEEK WILL BEGIN
SHOWING UP LATE WEDNESDAY. THE LOW LEVEL FLOW BECOMES SOUTHERLY
DURING THE AFTERNOON HOURS AND MOISTURE/CLOUD COVER BEGIN SURGING
NORTH INTO THE NORTHERN PLAINS. TEMPERATURES DURING THE DAY AND FOR
MOST OF THE OVERNIGHT HOURS WEDNESDAY NIGHT WILL REMAIN WARMER THAN
NORMAL...BUT BEGIN TO PLUNGE BEFORE DAYLIGHT THURSDAY WHEN ARTIC AIR
SURGES SOUTHWARD INTO THE BLKHLS REGION BEHIND THE FIRST SHORT WAVE.
EXTENDED...WX MAKER FOR THUR/FRI INTO EARLY SAT IS POWERFUL UPPER
LOW FCST TO MV THRU CENTRAL/NRN PLAINS DURING THE PERIOD. THIS
SYSTEM WILL BRING SNOW TO THE REGION FOR THURSDAY THROUGH FRIDAY
EVENING ALONG WITH MUCH COLDER TEMPS AND STRONG NW WINDS. MODELS
VARY ON EXACT TRACK OF LOW...ECMWF OVR WRN SD WITH GFS GOING ACRS
ERN SD.
ECMWF TRACK WOULD PRODUCE POWERFUL BLIZZARD ACRS WRN SD WITH HEAVY
UPSLOPE SNOWS IN BEAR LODGE/NRN BLACK HILLS. GFS TRACK WOULD BE LESS
SNOW AND WIND BUT LIKELY STILL TO PRODUCE DECENT UPSLOPE SNOWS. AT
THIS TIME WL GO WITH LIKELY POPS FOR THURDAY THRU FRIDAY/INCREASE NW
WINDS AND DROP TEMPS.
AFT SYS MOVES EAST SAT...LKS LIKE DRIER WX AND A WARMING TREND FOR
SUNDAY AND MONDAY. TEMPS SHOULD BOUNCE BACK TO NEAR NORMAL FOR
SUN/MON.
&&
.AVIATION...VFR CONDS ARE EXPECTED THROUGH THE FCST PERIOD.
$$
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
