000
FXUS63 KARX 291735
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1135 AM CST FRI NOV 29 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CST FRI NOV 29 2013

THE MAIN FOCUS THROUGH TONIGHT IS ON THE PRECIPITATION CHANCES IN
NORTH CENTRAL WISCONSIN AS A TROUGH MOVES INTO THE REGION.

A BROAD RIDGE OF SURFACE HIGH PRESSURE EXTENDS FROM CENTRAL CANADA
DOWN TO THE SOUTHEASTERN US UNDER NORTHWESTERLY FLOW ALOFT. SKIES
ARE MAINLY CLEAR THROUGHOUT THE UPPER MISSISSIPPI VALLEY THIS
MORNING...HOWEVER SOME HIGH LEVEL CLOUD COVER WILL MOVE IN THROUGH
THE DAY AS A LEAD WEAK MID LEVEL SHORT WAVE TROUGH COMES IN FROM
THE WEST.

THE MAIN MID LEVEL TROUGH IS CURRENTLY IN NORTHERN
ALBERTA/SASKATCHEWAN AND WILL DROP SOUTHEAST TOWARD LAKE SUPERIOR
TONIGHT. THE STRONGEST FORCING WILL BE OUT AHEAD OF THIS TROUGH
AND DOES NOT APPEAR TO GET INTO CLARK/TAYLOR COUNTY.
INSTEAD...THERE IS SOME WEAK LOW LEVEL FORCING VIA WARM AIR
ADVECTION. 29.00Z NAM/GFS SOUNDINGS SHOW THAT LOW LEVEL MOISTURE
INCREASES AS THIS LIFT COMES IN TONIGHT...BUT DOES NOT APPEAR TO
SATURATE UP HIGH ENOUGH FOR ICE TO BE INTRODUCED. EVEN IF THE ICE
DEVELOPS...THERE APPEARS TO BE ENOUGH OF A DEEP ENOUGH OF A DRY
LAYER THAT SEEDER-FEEDER PROCESSES WONT PRODUCE SNOW EITHER.
SO...IT LOOKS LIKE FREEZING DRIZZLE WILL BE THE MAIN PRECIPITATION
TYPE FOR CLARK/TAYLOR COUNTIES IN NORTH CENTRAL WISCONSIN...BUT
CAN NOT COMPLETELY RULE OUT SOME SNOW OCCURRING IF THE MOISTURE
IS DEEPER.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 326 AM CST FRI NOV 29 2013

A FAIRLY UNSETTLED WEEK IS ON TAP AS THE UPPER LEVEL FLOW SHOWS A
BROAD TROUGH DROPPING OUT OF THE DEPTHS OF NORTHWEST CANADA. THIS
DEEPENING TROUGH WILL DROP DOWN INTO THE ROCKIES EARLY IN THE
WEEK BEFORE TRACKING THROUGH THE REGION LATER IN THE WEEK. THE
FIRST MID LEVEL SHORT WAVE TROUGH TO EJECT EAST FROM THIS TROUGH
COMES THROUGH EARLY ON MONDAY AND SHOULD PRODUCE SOME LIGHT SNOW
WITH IT. A LITTLE EARLY FOR SNOW AMOUNTS...BUT THEY GENERALLY LOOK
TO BE ON THE LIGHTER SIDE.

AS THE MAIN TROUGH/SURFACE LOW APPROACH THE REGION INTO MID
WEEK...IT LOOKS LIKE WE WILL HAVE PERIODS OF PRECIPITATION COMING
THROUGH AS ADDITIONAL SHORT WAVE TROUGHS ROUND THE EASTERN
PERIPHERY OF THE MAIN TROUGH. THE 29.00Z GFS/ECMWF HAVE THE SAME
GENERAL IDEA WITH THE TIMING OF THE LOW/TROUGH PASSAGE...BUT HAVE
THE TRACK OF THE SURFACE LOW IN DIFFERENT SPOTS. THE ECMWF IS
FURTHER NORTHWEST AND IS A WARMER SOLUTION...INITIALLY...DUE TO
HOW DEEP IT BUILDS THE TROUGH. THIS ALSO CREATES A MUCH STRONGER
COLD PUSH THAT COMES IN BEHIND IT AND THOUGH IT IS BEYOND THE
SCOPE OF THIS FORECAST PACKAGE...TEMPERATURES ARE EXPECTED TO TAKE
A HUGE PLUNGE GOING INTO NEXT WEEKEND. DETAILS TO EMERGE WITH
LATER FORECASTS...BUT CURRENT INDICATIONS ARE FOR HIGHS IN THE
SINGLE DIGITS. CONFIDENCE IN THAT FORECAST WILL GO UP IF WE PUT
ANY SNOW DOWN ON THE GROUND BEFORE THAT COLD SURGE GETS IN TOWARD
NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1135 AM CST FRI NOV 29 2013

SOUTHERLY WINDS ARE BEGINNING TO INCREASE AT THE TAF SITES...
BETWEEN A DEPARTING HIGH PRESSURE RIDGE IN LOWER MI AND LOW
PRESSURE OVER THE DAKOTAS. THESE WINDS MAY GUST UPWARDS OF 20 KT
AT RST THIS AFTERNOON BEFORE NOCTURNAL COOLING ALLOWS THE GUSTING
TO DIMINISH. SOUTH WINDS WILL REMAIN BREEZY AT RST THROUGH THE
NIGHT...THOUGH...ON THE ORDER OF 15 KT. BOTH TAF SITES LOOK TO
EXPERIENCE LOW LEVEL WIND SHEAR FOR A 6-8 HOUR PERIOD TONIGHT AS
THE WINDS NEAR 2000 FT INCREASE TO 35-45 KT AND TURN
SOUTHWESTERLY. EXPECT THE WIND SHEAR TO DIMINISH LATE TONIGHT AS
THE TROUGH APPROACHES. THAT SAME TROUGH MOVING IN SHOULD RESULT IN
LIGHTER WINDS TOMORROW.

ASIDE FROM THE WINDS...NO OTHER AVIATION IMPACTS ARE EXPECTED WITH
VFR CONDITIONS FORECAST. THERE WAS A CONCERN AN MVFR STRATUS DECK
COULD DEVELOP LATER TONIGHT...BUT THE SOUTH WINDS ARE BRINGING IN
WARMER AIR JUST AS FAST AS THE ACCOMPANYING MOISTURE...WHICH
SHOULD PREVENT ANY LOW STRATUS DECK FROM FORMING.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM....HALBACH
AVIATION...AJ