FXUS63 KFSD 252054
AFDFSD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
254 PM CST WED NOV 25 2009

.DISCUSSION....
AS ELUDED TO IN MORNING UPDATE...TRICKY CLOUD COVER FORECAST 
TONIGHT. UPPER LEVEL LOW OVER THE WESTERN GREAT LAKES IS EXPECTED TO 
SHIFT EAST AND AS IT DOES SO GRADIENT SHOULD BEGIN TO RELAX AND 
STRATUS SHOULD SHIFT EAST.  BATCH OF STRATUS POISED TO THE NORTH 
ACROSS NORTH DAKOTA...HOWEVER...MUCH OF STRATUS TO THE WEST OF THE 
JAMES RIVER VALLEY APPEARS AS THOUGH IT IS DRIVEN BY MIXING.  18Z 
RUC HAS SLOWED THE PROGRESSION OF THE CLEARING...WITH 925 MB RH 
REMAINING HIGH ALONG AND EAST OF INTERSTATE 29 THROUGH MUCH OF THE 
NIGHT. NAM IS MUCH QUICKER TO CLEAR IT OUT AS UPPER LEVEL FORCING 
SHIFTS EAST. HAVE MENTION OF FLURRIES ACROSS EASTERN TWO TIERS OF 
COUNTIES ACROSS SOUTHWEST MINNESOTA AND NORTHWEST IOWA THROUGH EARLY 
EVENING...HOWEVER AS DENDRITIC LAYER DRIES OUT BELIEVE WILL JUST BE 
LEFT WITH LINGERING STRATUS.  CLOUDS AND WINDS WILL IMPACT 
LOWS...AND WITH SLOWER CLEARING...HAVE RAISED FORECAST LOWS 3-5 
DEGREES ALONG AND EAST OF INTERSTATE 29.  /BT

THURSDAY SHOULD BE A MILD DAY WITH MUCH LESS WIND TO WORRY ABOUT. A 
WEAK RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE CWA WHICH WILL 
ALLOW WINDS TO TURN FROM THE NORTHWEST TO THE WEST AND SOUTHWEST 
THROUGH THE DAY. MIXING WILL BE LIMITED BUT STILL LOOKS NICE. WENT 
WARMEST OVER SC SD WITH HIGHS RANGING FROM THE UPPER 30S IN SW MN TO 
AROUND 50 IN SC SD.

THURSDAY NIGHT WILL SEE A RELATIVELY WEAK SOUTHWEST FLOW IN THE LOW 
LEVELS SPREAD ACROSS WARMER TEMPERATURES IN THE LOW LEVELS. WITH A 
WEAK SFC GRADIENT...WENT WITH COOLER LOWS THAN PREVIOUSLY 
FORECAST...SO EXPECT A FAIRLY STOUT INVERSION TO DEVELOP BY FRIDAY 
MORNING. LOWS MAINLY IN THE 20S.

FRIDAY HAS THE POTENTIAL TO BE VERY NICE...JUST A MATTER OF HOW MUCH 
HIGH CLOUD COVER AND HOW MUCH OF AN EFFORT IT WILL TAKE TO WARM 
THINGS UP. FOR NOW...WILL TAKE THE OPTIMISTIC ROUTE AND LEAN TOWARDS 
VERY LITTLE CLOUD COVER IN THE AFTERNOON. MAYBE SOME HIGH CLOUDS IN 
THE MORNING...BUT NOT ENOUGH TO CREATE PROBLEMS. OTHERWISE...LOW 
LEVEL FLOW WILL BE WEAK AND WITH A DECENT AMOUNT OF SUNSHINE EXPECT 
EVERYONE TO GET INTO THE UPPER 40S TO MID 50S.

FRIDAY NIGHT A QUIET NIGHT WITH LIGHT WINDS...LOWS RANGING FROM THE 
MID 20S TO AROUND 30.

SATURDAY WILL BEGIN TO SEE UPPER LEVEL SUPPORT WORK INTO THE ROCKIES 
BUT PRECIPITATION NOT EXPECTED DURING THE DAY...AND CLOUD COVER WILL 
AGAIN BE MINIMAL...BUT SHOULD INCREASE THROUGHOUT THE AFTERNOON. 

IN THE LATTER PERIODS(SUN/WED)...OVERALL...FEW CHANGES IN THE MODELS 
FROM YESTERDAY. NORTHERN STREAM WAVE EXPECTED TO SWING A COLD FRONT 
THROUGH ON SATURDAY AS A STRONG JET STREAK DEVELOPS OVER THE 
SOUTHWEST UNITED STATES. MOST INDICATIONS ARE THAT THIS STRONG JET 
STREAK WILL NOT PHASE WITH THE NORTHERN STREAM AND IF IT DOES...IT 
WILL BE TO THE EAST OF THE AREA. SO...PRETTY MUCH THINKING DRY 
THROUGH THE PERIOD WITH BELOW NORMAL TEMPERATURES. TUESDAY STILL A 
LITTLE UP IN THE AIR AS ANOTHER NORTHERN STREAM WAVE IS EXPECTED TO 
DEVELOP OVER THE NORTHWEST UNITED STATES AND DROP SOUTHEAST INTO THE 
NORTHERN PLAINS LATE TUESDAY INTO WEDNESDAY. THE MAIN THREAT HERE 
WILL BE A POTENTIAL FOR ABOVE NORMAL TEMPERATURES LATE MONDAY INTO 
TUESDAY THEN POTENTIALLY SOME SNOW ON WEDNESDAY. VERY LITTLE 
AGREEMENT HOWEVER AMONGST THE VARIOUS MODELS AND GFS ENSEMBLE HAS A 
PRETTY HIGH STANDARD DEVIATION OVER ALL OF THE NORTHERN PLAINS. 
OVERALL...WILL SIDE CLOSEST TO THE 12Z GFS/0Z ECMWF. AFTER 
THIS...LOOKS LIKE A PRETTY GOOD CHANCE FOR BELOW NORMAL TEMPERATURES 
FROM WEDNESDAY THROUGH THE REMAINDER OF THE WEEK. /08

&&

.AVIATION...
MVFR CONDITIONS LINGERING EAST OF THE JAMES RIVER VALLEY LATE THIS 
AFTERNOON.  APPEARS AS THOUGH CLOUD COVER EAST OF THE JAMES MAY 
LINGER THROUGH EARLY EVENING HOURS...THEN STUBBORNLY GRADUALLY 
SHIFTING EAST.  COULD SEE PERIODS OF SNOW REDUCE VISIBILITIES ALONG 
A LINE FROM KMWM TO KSLB TO 2-4 SM AT TIMES THROUGH 00Z THURSDAY. 
THEREAFTER...EXPECT ANY LINGERING FLURRIES TO REDUCE VISIBILITY TO 
5SM THROUGH 03Z...WITH UNRESTRICTED VISIBILITIES THEREAFTER. 
NORTHWEST WINDS WILL DECREASE OVERNIGHT AND REMAIN FAIRLY LIGHT ON 
THURSDAY AS AN AREA OF HIGH PRESSURE SLIDES TO THE SOUTH OF FORECAST 
AREA. 

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

$$