FXUS63 KFSD 042135
AFDFSD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA 
NATIONAL WEATHER SERVICE SIOUX FALLS SD
330 PM CST FRI DEC 4 2009

.DISCUSSION...

SFC RIDGE OF HIGH PRESSURE WL CONT TO SLIDE OFF TO THE EAST OF THIS 
FA TONIGHT...BRINGING THE WINDS AROUND TO A LIGHT SLY DIRECTION. 
THIS MAKES THE MIN TEMPS TONIGHT RATHER PROBLEMATIC. FIRST OF ALL... 
THE STRATOCU IN NW IA WL EITHER EXIT OR DRY UP BY SUNSET...LEAVING 
ONLY CI TO BE FOUND THRU THIS AREA. CI HAS BEEN STREAMING SWD ALL 
AFTERNOON DOWN THE ERN HALF OF THE FA FM S CENTRAL CANADA...DUE TO 
AN UPPER LOW IN THAT REGION. THIS CI SHOULD EXIT THIS EVENING...ONLY 
TO BE REPLACED BY MORE CI ENTERING FM WRN CANADA OVERNIGHT AND LATE 
TONIGHT. IT IS DOUBTFUL WHETHER THESE HIGH CLOUDS WL BE THICK ENOUGH 
TO MODERATE ANY TEMPERATURES. HOWEVER...THE LIGHT SOUTH WINDS COULD. 
THEREFORE DID NOT TOTALLY PLUMMET THE MINS LIKE A ROCK...DESPITE 
SOME NEW SNOW COVER OVER PARTS OF OUR EAST. BUT DID HEDGE THEM ONCE 
AGAIN TOWARD THE COOLER MET GUIDANCE WHICH WORKED WELL IN THIS COLD 
AIRMASS LAST NIGHT. I ACTUALLY PLACED THE LOWEST TEMPS AROUND 
07Z-09Z LATE TONIGHT. THEN WITH THE LIGHT SOUTH WIND...BEGAN TO 
STEADY THEM OUT AND EVEN ROSE SOME OF THEM SLIGHTLY BEFORE SUNRISE. 
/MJF

SATURDAY LOOKING TO BE THE NICER DAY OF THE NEXT FEW WITH MODERATING 
TEMPERATURES. WINDS WILL BE FROM THE SOUTH EARLY IN THE DAY...THEN 
TAKE ON A NORTHERLY COMPONENT LATER IN THE DAY WITH THE PASSAGE OF A 
WEAK BOUNDARY. WILL KEEP A GOOD BIT OF HIGH CLOUDINESS THROUGH THE 
DAY...THEN SOME LOWER CLOUDS MOVE INTO OUR NORTH LATER IN THE 
AFTERNOON WITH THE PASSAGE OF THE BOUNDARY.  HIGHS WILL RANGE FROM 
THE MID/UPPER 20S NORTH TO THE MID 30S SOUTHEAST.

MODELS TRENDING FARTHER SOUTH WITH SUNDAYS SYSTEM...WITH THE NAM 
OFFERING THE NORTHERN MOST SOLUTION. THE GFS WOULD KEEP ALMOST ALL 
OF THE PRECIP SOUTH OF OUR AREA...WITH THE ECMWF OFFERING AN 
INTERMEDIATE SOLUTION. ANYWAY...NOT A WHOLE LOT EXPECTED IN TERMS OF 
QPF...WITH AREAS MAINLY ALONG THE MISSOURI RIVER CORRIDOR INTO 
NORTHWEST IOWA AFFECTED...WHERE UP TO AN INCH OR TWO COULD 
ACCUMULATE...WITH THE HIGHER AMOUNTS IN OUR FAR SOUTHEAST. WITH 
COLDER AIR CONTINUING TO FILTER SOUTHWARD...HIGHS ON SUNDAY WILL BE 
COOLER...IN THE UPPER TEENS TO LOWER 20S. WILL HAVE ANOTHER BREAK ON 
MONDAY AS A SURFACE RIDGE BUILDS INTO THE NORTHERN PLAINS WITH HIGHS 
SIMILAR TO SUNDAY.

FARTHER INTO NEXT WEEK...MODELS IN PRETTY GOOD AGREEMENT WITH THE 
UPPER LEVEL LOW WHICH WILL SWING OUT OF COLORADO ON TUESDAY. COULD 
SEE SOME LIGHT SNOW BREAK OUT OVER THE CWA ON MONDAY NIGHT WITH 
MIDLEVEL WAA IN ADVANCE OF THE SYSTEM...THEN A BETTER CHANCE ON 
TUESDAY AS THE LOW TRACKS THROUGH THE CENTRAL/SOUTHERN PLAINS. AT 
THIS POINT...TRACK LOOKS FAR ENOUGH TO THE SOUTH THAT MAINLY OUR 
SOUTHERN AREAS WILL BE AFFECTED. WHILE THERMAL PROFILES WARM 
SLIGHTLY ON TUESDAY...WITH MORE CLOUDINESS HIGHS MAY BE A COUPLE OF 
DEGREES COOLER THAN ON MONDAY. AFTER THAT...MODELS INDICATING SOME 
REALLY COLD AIR DRAINING IN BEHIND THE EXITING SYSTEM...WITH 925 MB 
TEMPERATURES ON WEDNESDAY SOMEWHERE IN THE RANGE OF -12 TO -17 C 
ACROSS THE CWA...SO LOWERED MIN/MAXS FOR WEDNESDAY. THE SHORTWAVE 
TRAIN LOOKS TO CONTINUE TOWARD THE END OF NEXT WEEK...WITH MODELS 
POINTING TOWARD ANOTHER SYSTEM PUSHING OUT OF THE CENTRAL ROCKIES IN 
THE LATE THURSDAY TO FRIDAY TIME FRAME...THOUGH AGAIN APPEARS THAT 
GREATEST THREAT OF SNOW WILL BE IN OUR SOUTH. WHILE THERE WILL BE 
SOME WARMING FOR THE END OF THE WEEK...TEMPERATURES LOOK TO REMAIN 
BELOW NORMAL.  /JM

&&

.AVIATION...

LAST REMNANTS OF THIS AFTERNOONS STRATOCU...WHICH IS NEAR THE 
THRESHOLD OF MVFR/VFR...WL EXIT NW IA OR DRY UP AT SUNSET. THEREFORE 
TONIGHT AND SATURDAY MORNING WL BE VFR...ALTHOUGH WITH LIGHT SLY 
WINDS ONE CANNOT RULE OUT MVFR TYPE FOG AROUND SUNRISE SATURDAY. 
/MJF

&&

.FSD WATCHES/WARNINGS/ADVISORIES...

SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

$$