FXUS63 KARX 010822
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
222 AM CST TUE DEC 1 2009

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT

MAIN FORECAST CONCERN IS WITH TEMPERATURES...AS CLOUD COVER AND
PERIODIC LIGHT SNOW CHANCES LINGER THROUGH THE SHORT RANGE PERIOD.

08Z SURFACE ANALYSIS SHOWS THE AREA UNDER THE INFLUENCE OF A WEAK
RIDGE OF HIGH PRESSURE BETWEEN TWO SYSTEMS.  ONE SYSTEM DEPARTING
ACROSS THE NORTHERN GREAT LAKES REGION...WHILE ANOTHER IS
PROGRESSING THROUGH WESTERN ND. SOME MID AND HIGH CLOUD STREAKING
ACROSS THE SKY OVERNIGHT...BUT THE THICKEST AND LOWEST CLOUD COVER
WELL TO THE NORTHEAST AND WEST.

PERUSAL OF VARIOUS SHORT TERM MODEL SOLUTIONS SHOW ALL IN PRETTY
REASONABLE AGREEMENT WITH THE PROGRESSION OF FEATURES ACROSS THE
REGION THROUGH MID-WEEK. LOOKING LIKE WE WILL FINALLY MAKE THE
TRANSITION TO MORE WINTER-ISH CONDITIONS.

THE LOW TO OUR WEST...AND ITS ASSOCIATED UPPER LEVEL SHORT WAVE
TROUGH...WILL MOVE INTO NORTHERN MN BY AFTERNOON...CONTINUING INTO
THE UPPER PENINSULA OF MICHIGAN BY WEDNESDAY MORNING. THIS TRACK
WILL KEEP THE THREAT FOR ANY SIGNIFICANT SNOWFALL WELL TO OUR NORTH.
HOWEVER...AMPLE COLD ADVECTION BEHIND A STRONG COLD FRONT ASSOCIATED
WITH THE SYSTEM SHOULD WORK TO WRING OUT WHAT LIMITED MOISTURE IS
AVAILABLE IN THE BOUNDARY LAYER FOR AT LEAST THE THREAT FOR SOME
LIGHT SNOW OR FLURRIES STARTING LATE WEDNESDAY.  THE FLOW PATTERN
THEN LOOKS TO REALLY BOG DOWN. THE MODELS HAVE ALL TRENDED TOWARD A
LARGE CLOSED LOW OVER EASTERN ONTARIO...WITH SEVERAL SHORT WAVE
TROUGHS ROTATING AROUND IT. THIS WILL KEEP THE PARADE OF COLD AIR
COMING INTO THE UPPER MIDWEST...ALONG WITH AMPLE CLOUD COVER AND
OFF/ON CHANCES FOR LIGHT SNOW.

AFTER A SOMEWHAT MILD DAY TODAY...LOOK FOR TEMPERATURES TO TAKE THE
PLUNGE BACK DOWN TO NORMAL OR BELOW NORMAL FOR EARLY DECEMBER FOR
THE REMAINDER OF THE WEEK. TEMPERATURES SHOULD NOT MOVE MUCH ON
WEDNESDAY WITH COLD ADVECTION ON BRISK NORTHWEST WINDS. DID TEMPER
THE LOW TEMPERATURES WEDNESDAY NIGHT AND THURSDAY NIGHT. WARMED
THEM A FEW DEGREES TO ACCOUNT FOR THE BLANKET OF CLOUD COVER THAT IS
EXPECTED TO BE AROUND. ALL GUIDANCE WAS WARMER THAN WHAT WE HAD
GOING...SO OPTED TO TREND UPWARD.

.LONG TERM...FRIDAY THROUGH MONDAY

MEDIUM RANGE MODEL SOLUTIONS SHOW THE LARGE UPPER TROUGH TO BEGIN
SHIFTING EAST OF THE REGION LATE IN THE WEEK...BUT THERE IS ALSO
ANOTHER CLOSED CIRCULATION OVER THE PACIFIC NORTHWEST THAT IS
POISED TO MOVE IN BEHIND IT.  MODELS STILL HAVING SOME DIFFICULTY
WITH JUST HOW TO HANDLE THIS FEATURE...AND THE EASTWARD TRANSLATION
OF THE LARGE EASTERN TROUGH. WILL NOT MAKE ANY ADJUSTMENT FROM THE
PREVIOUS FORECAST AT THIS POINT...BUT IT APPEARS THE REGION WILL
REMAIN IN OVERALL TROUGHINESS INTO NEXT WEEK.

&&

.AVIATION...TODAY AND TONIGHT

LOOK FOR VFR CONDITIONS TO PERSIST THROUGH MUCH OF TONIGHT...THANKS
TO A DRY LOW LEVEL AIRMASS IN PLACE. SOME CIRRUS CLOUDS ARE EXPECTED
TO CROSS THE TAF SITES THROUGH THE DAY TODAY. EARLY THIS EVENING...A
COLD FRONT WILL MOVE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
REGION...CAUSING WINDS TO SWITCH FROM SOUTHWEST TO NORTHWEST. IN
ADDITION...PLAN ON ALTOSTRATUS CLOUDS TO FORM IN THE WAKE OF THE
FRONT. BETWEEN VERY LATE TONIGHT AND EARLY WEDNESDAY AFTERNOON...A
STRATUS DECK IS FORECAST TO INVADE BOTH TAF SITES FROM THE
NORTHWEST. CEILINGS SHOULD EITHER BE VFR OR HIGH MVFR.

&&

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

$$

SHORT/LONG TERM...MW
AVIATION..........AJ