FXUS63 KARX 012025
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
ISSUED BY NATIONAL WEATHER SERVICE QUAD CITIES IA IL
225 PM CST TUE DEC 1 2009

.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT

PRIMARY FOCUS IS TEMPERATURES AS COLD FRONT PUSHES THROUGH
TONIGHT...THEN CHANCES FOR SNOW SHOWERS OR FLURRIES LATER THIS
WEEK. 

AT 19Z...SURFACE ANALYSIS INDICATED LOW PRESSURE CENTERED OVER NW
MN WITH ASSOCIATED COLD FRONT EXTENDING SOUTH INTO NW IA AND SE
NEB. A WEAK WARM FRONT STRETCHED SE ACROSS CENTRAL MN THROUGH S
CENTRAL WI. SOUTH OF THIS BOUNDARY...TEMPERATURES HAD WARMED INTO
THE UPPER 40S TO LOWER 50S ON SRLY WINDS OVER THE SOUTHERN 2/3RDS
OF THE CWA.

SH0RT TERM MODELS FAIRLY STRAIGHT FORWARD DEPICTING THE LOW
CONTINUING TO TRACK EAST...TO SOUTH OF DLH BY 00Z...IN THE AREA OF
HIGHEST 3 HOUR PRESSURE FALLS AT 18Z. IT THEN CONTINUES EAST
ACROSS UPPER MI OVERNIGHT DRAGGING THE COLD FRONT EAST ACROSS THE
FORECAST AREA IN THE EVENING. EXTENSIVE AREA OF LIGHT SNOW ON SURFACE
OBSERVATIONS ACROSS FAR NRN MN AND ND WILL REMAIN WELL TO THE
NORTH ALONG THE LOW LEVEL DEF ZONE AND PRIMARY UPPER LEVEL FORCING
WITH THE UPPER LEVEL SHORTWAVE TROUGH. TIGHT POST FRONTAL
PRESSURE GRADIENT AND MID LEVEL SHORTWAVE SUBSIDENCE WILL RESULT
IN BRISK NW WINDS AND STRONG LOW LEVEL COLD ADVECTION OVERNIGHT.
HAVE ADJUSTED FOR NON-DIURNAL HOURLY TEMPERATURES EARLY TO ACCOUNT
FOR THE FRONTAL PASSAGE IN THE EVENING AND TWEAK MINS SOME...STILL
EXPECTING WIDESPREAD MID 20S WITH PARTIAL CLEARING IN THE NORTH BY
MORNING.

WED THROUGH FRI...BROAD CYCLONIC LOW LEVEL FLOW LINGERS UNDER
DEVELOPING UPPER LOW AND TROUGH OVER ONTARIO TO KEEP COLD AIR IN
PLACE WITH LOW CHANCES FOR FLURRIES. MODELS HAVE STRONGEST UPPER
FORCING IN LATE WED NIGHT INTO THU TIMEFRAME AND HAVE CHANCE POPS
FOR SNOW SHOWERS FOR THU. OTHERWISE...DIFFICULT TO RULE OUT PERIODS
WITHOUT POTENTIAL FOR LIGHT SNOW SHOWERS OR MORE LIKELY FLURRIES
DUE TO LINGERING MOISTURE AND INSTABILITY IN LOW TO MID LEVELS AND
HAVE SLIGHT CHANCE POPS. AS ADVERTISED...TEMPERATURES TAKE A TURN
TO NEAR TO BELOW NORMAL THROUGHOUT WITH HIGHS ONLY IN THE UPPER
20S AND LOWER 30S AND LOWS IN THE TEENS AND 20S BY FRI AM.

.LONG TERM...SATURDAY THROUGH TUESDAY
CONSIDERABLE UNCERTAINTY EXISTS IN THE LONG TERM...ESPECIALLY
TOWARD MON AND TUE AS UPPER LOW OVER ONTARIO LIFTS NE LEAVING MORE
ZONAL MID LEVEL FLOW WITH EMBEDDED SHORTWAVES IMPACTING THE AREA.
AS HTS BEGIN TO RISE SAT AND SUN...TEMPERATURES SHOULD RETURN
CLOSER TO EARLY DECEMBER CLIMO. MEDIUM RANGE MODELS ADVERTISE NEXT
SIGNIFICANT SYSTEM TO POSSIBLY AFFECT THE AREA AROUND TUE INTO
WED. AS CAN BE EXPECTED...THERE ARE CONSIDERABLE DIFFERENCES IN
TIMING AND TRACK...WITH THE ECMWF FASTER AND TRACKING A CYCLONE
LIFTING OUT OF THE CENTRAL PLAINS ON A MORE NRLY PATH COMPARED TO
A SLOWER MORE SRLY GFS. FOR NOW...HAVE GONE WITH COMPROMISE SLIGHT
CHANCES FOR LIGHT SNOW TUE RISING TO LOW CHANCES TUE NIGHT.

&&

.AVIATION...
VFR CONDITIONS THROUGH PERIOD WITH VSBYS AOA 7 MILES.  BKN-OVC HIGH 
CLOUDS TO ARRIVE AFTER 00Z. EXPECT CIGS OF 15-20 PLUS KFT AGL
UNTIL 18Z...THEN CLEARING. NORTHWEST WINDS TO INCREASE TO 10-20
KTS BY WEDNESDAY MORNING WITH SOME HIGHER GUSTS WEDNESDAY MID DAY.
THIS COMBINED WITH COLD AIR ADVECTION COULD PRODUCE LIGHT TO
MODERATE CHOP AFTER 14Z LOWEST 2KFT AGL UNTIL DUSK WEDNESDAY.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT/LONG TERM...SHEETS
AVIATION...NICHOLS