Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 211753
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1153 AM CST FRI NOV 21 2014

.UPDATE...
ISSUED AT 1153 AM CST FRI NOV 21 2014

BASED ON FREEZING RAIN AND DRIZZLE POTENTIAL BEFORE 11 PM...HAVE
DECIDED TO BACK UP THE ADVISORY START TIME ACROSS OUR SOUTHERN
AREA TO 9 PM.

AFTER ASSESSING THE DEPTH OF THE MOISTURE LAYER MOVING NORTHWARD
INTO THE AREA...AND WITH MORE TRAVELERS WITH DEER HUNTING WEEKEND
IN WISCONSIN...HAVE DECIDED TO EXPAND THE FREEZING RAIN ADVISORY
NORTHWARD TO I-90 IN WISCONSIN. THIS IS A LOWER PROBABILITY AREA
FOR IMPACT BUT FEEL THAT SOME LIGHT GLAZING IS POSSIBLE ON THE
NORTHWEST EXTENT OF THE MOISTURE SURGE HEADING IN.

MAIN IMPACT AREA WILL STILL BE EASTERN IA...SOUTHERN WI...AND NRN
IL FOR ICING. FRINGE COUNTIES ON NW SIDE OF ADVISORY WE EXPECT
MINOR/PATCHY IMPACT AND LOWER ICING COVERAGE. JUST CANT MESS
AROUND WITH ICING...JUST A BIT WILL CAUSE PROBLEMS.

&&

.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 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1131 AM CST FRI NOV 21 2014

INCREASING SOUTHERLY WINDS THIS MORNING...IN THE 10-20 KT RANGE
AND STRONGEST AT RST...HAS HELPED BRING MORE MOISTURE INTO THE TAF
SITES. THE BREEZY WINDS WILL CONTINUE THROUGH SATURDAY...BRINGING
IN A STRATUS DECK THATS RACING NORTHEASTWARD OUT OF THE CENTRAL
PLAINS. THOSE WINDS ARE PROGGED STRONG ENOUGH TO EVEN WARRANT A
LOW LEVEL WIND SHEAR MENTION AT LSE FOR MUCH OF TONIGHT. ANTICIPATING
THE STRATUS DECK TO MOVE INTO THE TAF SITES IN THE 02-03Z TIME
WINDOW AS AN MVFR CEILING...LOWERING TO IFR AT RST BY 05Z. SOME
FREEZING DRIZZLE IS POSSIBLE AROUND 06Z AT LSE AT THE ONSET...
CHANGING OVER TO DRIZZLE A FEW HOURS LATER AS AIR TEMPERATURES
WARM. BOTH SITES SHOULD SEE FURTHER LOWERING OF CEILINGS AS WE
APPROACH 12Z SATURDAY IN RESPONSE TO CONTINUED MOISTURE BEING
PUSHED INTO THE COLDER AIR HERE. VISIBILITIES COULD EVEN START TO
BE IMPACTED...ESPECIALLY AT THE HIGHER TERRAIN OF RST WHERE MVFR
MENTION IS ADDED.

LOOKING AHEAD...CONDITIONS REMAIN FAVORABLE FOR A DENSE FOG EVENT
SATURDAY NIGHT INTO SUNDAY MORNING...ESPECIALLY AT RST.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY FROM 9 PM THIS EVENING TO 8 AM CST
     SATURDAY FOR WIZ054-055-061.

     FREEZING RAIN ADVISORY FROM 11 PM THIS EVENING TO 8 AM CST
     SATURDAY FOR WIZ041>044-053.

MN...FREEZING RAIN ADVISORY FROM 11 PM THIS EVENING TO 8 AM CST
     SATURDAY FOR MNZ096.

IA...FREEZING RAIN ADVISORY FROM 9 PM THIS EVENING TO 8 AM CST
     SATURDAY FOR IAZ008>011-018-019-029-030.

&&

$$

UPDATE...BAUMGARDT
SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...AJ


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