Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 211140
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CST FRI NOV 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CST FRI NOV 21 2014

CHALLENGES INCLUDE FREEZING PRECIP TONIGHT AND OVERALL EVOLUTION OF
PRECIP TYPE AND AMOUNTS THROUGH MONDAY AS A STRONG EASTERN PACIFIC
WAVE MOVES ACROSS THE UPPER MIDWEST. 21.00Z ECMWF/GFS/NAM IN GOOD
OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION.

FLOW ALOFT BECOMES MORE ZONAL TODAY ALLOWING FOR WARM AIR ADVECTION
REGIME TO OVERSPREAD THE FORECAST AREA. CLEAR SKIES THIS MORNING
WILL GIVE WAY TO INCREASING CLOUD COVER THROUGH THE AFTERNOON. WITH
WARMER AIR ALOFT...TEMPERATURES WILL RISE INTO THE MID TO UPPER 20S
AND PERHAPS EVEN A FEW SPOTS WILL REACH 30 DEGREES. WINDS WILL BE
BREEZY TODAY FROM THE SOUTH WITH OCCASIONAL GUSTS TO 25 MPH ACROSS
SOUTHEAST MN AND NORTHEAST IA.

ATTENTION THEN TURNS TO THIS EVENING AND OVERNIGHT AS 0-2 KM
MOISTURE SURGES NORTHWARD ALONG 30 TO 40 KT 850 HPA JET. WITH VERY
DRY AIR ALOFT...THERE WILL BE NO ICE INTRODUCED INTO THE CLOUD. LOW-
LEVEL WARM AIR ADVECTION AND ISENTROPIC LIFT ON THE 275 K SURFACE
RESULTS IN OMEGA VALUES AROUND 3 UBAR/S IN THIS SUPERCOOLED
SATURATED LAYER...PRODUCING PERIODS OF DRIZZLE. ALTHOUGH SURFACE
TEMPERATURES WILL BE WARMING TO ABOVE FREEZING OVERNIGHT...ROAD
SURFACES WILL REMAIN BELOW 32 DEGREES AND EXPECT SLICK CONDITIONS
TO DEVELOP WITH A GLAZE OF ICE. CONFIDENCE HIGHEST ACROSS NORTHEAST
IA INTO SOUTHWEST WI AND WILL ISSUE A FREEZING RAIN ADVISORY FOR
THESE AREAS FROM 22.05Z TO 22.14Z.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 353 AM CST FRI NOV 21 2014

DRIZZLE DIMINISHES FROM WEST TO EAST ON SATURDAY AS PRIMARY LOW-
LEVEL MOISTURE PLUME SHIFTS TO THE EAST. TEMPERATURES WILL RISE
INTO THE UPPER 30S TO LOWER 40S WITH LIGHT SOUTHWEST WIND. RAIN
CHANCES INCREASE AGAIN SATURDAY NIGHT FROM SOUTH TO NORTH AS
ATMOSPHERIC COLUMN CONTINUES TO WARM AND SATURATES UP TO 700 HPA.

SUNDAY WILL BE WARM AND WET AS PRIMARY SURFACE LOW LIFTS FROM THE
SOUTHERN PLAINS TO THE SOUTHERN TIP OF LAKE MICHIGAN BY 24.06Z.
PRECIP TYPE WILL BE ALL RAIN WITH A FULLY SATURATED COLUMN AND
A THERMAL PROFILE ABOVE FREEZING TO 750 HPA. AFTERNOON HIGHS WILL
SOAR INTO THE MID 40S. PRECIP WILL GRADUALLY CHANGE OVER TO ALL
SNOW SUNDAY NIGHT INTO MONDAY MORNING AFTER MID-LEVEL COLD FRONT
SWEEPS ACROSS THE REGION. ACCUMULATING SNOWFALL IS POSSIBLE
THROUGH THE DAY ON MONDAY IN WRAP-AROUND DEFORMATION ZONE...BUT
AMOUNTS LOOK TO BE ONLY A FEW INCHES AT MOST.

SNOW WILL DIMINISH FROM WEST TO EAST ON TUESDAY...BUT WITH A
RETURN TO A FREEZING AIR MASS. DAY TO DAY TEMPERATURES WILL SLOWLY
FALL THROUGH THE REMAINDER OF THE WEEK WITH HIGHS ON THURSDAY BACK
INTO THE TEENS TO LOWER 20S AND LOWS IN THE LOWER TO MID TEENS.
THE NEXT BEST CHANCE FOR SNOW WILL BE WEDNESDAY AND WEDNESDAY
NIGHT AS THE NEXT SHORT-WAVE DROPS SOUTH FROM CANADA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 540 AM CST FRI NOV 21 2014

HIGH PRESSURE WILL PROVIDE VFR CONDITIONS THROUGH TODAY. AS THE
HIGH SLIPS EAST INTO THE GREAT LAKES REGION THIS BY THIS
AFTERNOON...LOOK FOR INCREASING SOUTH WINDS ALONG WITH AN INCREASE
IN ALTOCUMULUS CLOUDS WITH BASES AOA 12KFT. A SURGE OF MOISTURE
AHEAD OF AN APPROACHING TROUGH OVER THE PLAINS WILL THEN SPREAD
STRATUS INTO THE AREA THIS EVENING THROUGH TONIGHT WITH CIGS
EXPECTED TO DETERIORATE INTO MVFR/IFR CATEGORY. WILL ALSO HAVE TO
KEEP AN EYE ON FREEZING DRIZZLE POTENTIAL LATE TONIGHT INTO EARLY
SATURDAY MORNING. BEST MOISTURE SURGE FOR THIS POTENTIAL LOOKS TO
BE ACROSS NORTHEAST IA INTO FAR SOUTHWEST WI...OR JUST SOUTH OF
THE KRST/KLSE TAF SITES. KEPT MENTION OUT FOR NOW...BUT WILL HAVE
TO MONITOR CLOSELY.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY FROM 11 PM THIS EVENING TO 8 AM CST
     SATURDAY FOR WIZ054-055-061.

MN...NONE.
IA...FREEZING RAIN ADVISORY FROM 11 PM THIS EVENING TO 8 AM CST
     SATURDAY FOR IAZ008>011-018-019-029-030.

&&

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...DAS



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