FXUS63 KFSD 031037
AFDFSD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA 
NATIONAL WEATHER SERVICE SIOUX FALLS SD
435 AM CST THU DEC 3 2009

.DISCUSSION...
WINTER LIKE PATTERN FINALLY GETTING MORE ACTIVE...AND MODELS 
STARTING TO SHOW MORE POTENTIAL FOR A CHANGE. SNOW SHOWERS ASSCD 
WITH COLD CORE UPR LOW MOVG ESEWD OVER NERN HLF CWA THIS MRNG...
WITH ALREADY REPORTS UP TO AN INCH NORTH OF FSD. SHOULD BE 1 TO
2 INCHES OF SNOW VCNTY SW MN THRU EARLY MRNG WITH ISOLD 3 INCHES 
PSBL IN UPSLOPE AREAS OF BUFFALO RIDGE...BEFORE TAPERING OFF FM NW 
TO SE BY LATE MRNG...FASTER THAN MODELS SEEM TO SHOW. OTRW WILL
KEEP SCT TO CHC OF -SHSN IN MUCH OF CWA THRU TDA WITH RELATIVELY 
MOIST UNSTABLE NWLY FLOW OF COLD AIR...DOWN TO SCT FLURRIES TONIGHT. 
CLOUDINESS AND A FEW FLUR SHOULD LINGER EAST OF JAMES RIVER FRI AS 
PER PREV FCST...MOSTLY CLEARING OUT FM W TO E THRU FRI NGT WITH 
DECENT RADIATIONAL COOLING. SATURDAY A NICE TRANSITION DAY AHEAD OF 
NEXT POTENTIAL SYSTEM...WITH SLY FLOW OF MILDER AIR...ESP AFFECTING
THE FAR SRN CWA WHERE ANY SNOW ON THE GROUND WILL BE MINIMAL. 
COMPOSITE OF LATEST MODELS...ESP GFS...SHOW STG UPR TROF DIGGING 
DOWN INTO RCKYS THRU SAT NGT...THEN SWINGING NEWD OUT OVER CNTRL 
PLAINS SUN...AND OVER IOWA AND SRN MN SUN NGT. IF NOT FOR THE FAIRLY 
FAST MOVEMENT OF THIS SYSTEM IT WOULD HAVE THE POTENTIAL FOR SOME 
HEAVY SNOW DUE TO DVLPG NEG TILT AND EFFICIENT ISENTROPIC LIFT FOR 
THE SERN HLF OF THE CWA. IN THE MEANTIME UPPD CHCS SNOW TO 50 PCT
SE TO ONLY 20 TO 30 PCT CHC -SN NW IN CWA FOR SUN AFTN THRU SUN NGT. 
MODELS COULD ALSO UNDERESTIMATE THE NEXT SYSTEM DVLPG INTO CNTRL 
PLAINS FOR TUES...BUT IT COULD STEER MORE SOUTH OF AREA...AND WILL 
HAVE TO MONITOR. CUT BACK HIGHS SOME FOR MON WITH EXPCD NLY FLOW
AND PSBL NEW SNOW COVER./ RYRHOLM

&&

.AVIATION...
AVERAGE CONDITIONS WILL LIKELY BE MVFR TDA ACRS THE AREA. WIDESPREAD 
LIGHT SNOWFALL WILL CONTINUE TO CIRCULATE THROUGH AREAS MAINLY EAST 
OF A KHON TO KSUX AREA. SOME OF THE LOWER VSBYS WL CERTAINLY DIP 
INTO THE IFR CATEGORY MAINLY ALG/E OF I29 THRU THE MORNING...BUT
THE OVERALL BRIEF PERIOD AT THESE LEVELS LKLY WOULD KEEP FROM 
MENTION IN TAFS...OTHER SOME SELECTED TEMPO MENTIONS AT SHORTEST 
TERM. /CHAPMAN

&& 

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

$$