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000
FXUS63 KARX 220425
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1025 PM CST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

CHALLENGES ABOUND WITH UPCOMING WINTER STORM TONIGHT THROUGH
CHRISTMAS EVE...WITH PRIMARY CONCERNS BEING PRECIPITATION TYPE
AND AMOUNTS. SURFACE LOW TRACK AND TIMING FROM 21.12Z MODEL SUITE
IN REASONABLE AGREEMENT AND WITH FAIRLY SIMILAR THERMAL/MASS
PROFILES...WILL USE A BLENDED SOLUTION THAT MATCHES WELL WITH
LATEST WPC SNOW AMOUNTS.

FOR TONIGHT...LIGHT PRECIPITATION CURRENTLY ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE TO LIFT NORTHEAST UNDER
WEAK ISENTROPIC LIFT REGIME. EXTENDED DRIZZLE MENTION THROUGH
22.12Z AS SOUNDINGS SHOW A 3000 TO 5000 FT DRY LAYER IN THE MID-
LEVELS THAT SHOULD BE DEEP ENOUGH TO PRECLUDE THE SEEDER-FEEDER
PROCESS. ANY SNOW SHOULD BE MAINLY CONFINED TO TAYLOR/CLARK
COUNTIES WHERE SURFACE TEMPERATURES SHOULD HOVER ABOUT THE
FREEZING MARK. UP TO A HALF INCH ACCUMULATION IS POSSIBLE. ALSO
EXPECT AREAS OF FOG THROUGH THE NIGHT.

SURFACE LOW DROPS FROM SOUTHEAST SD AT 22.12Z INTO CENTRAL IOWA BY
23.12Z. WARM AIR ADVECTION/ISENTROPIC LIFT INDUCED PRECIPITATION
WILL LIFT NORTH AND EAST THROUGH THE DAY...SPREADING ACROSS THE
ENTIRE FORECAST AREA BY MONDAY AFTERNOON. MAXIMUM WEB-BULB
TEMPERATURE THROUGH THE COLUMN REMAINS WITHIN A DEGREE OF ZERO
CELSIUS ACROSS THE REGION. NEAR SURFACE TO 850 HPA LAYER
EVENTUALLY SATURATES ALONG AND JUST BELOW THE ZERO CELSIUS
ISOTHERM. WITH SURFACE TEMPERATURES GENERALLY IN THE MID 30S...
INTRODUCED PERIODS OF A RAIN/SNOW MIX THROUGH THE DAY. UNLESS
SNOWFALL RATE CAN EXCEED THE AFFECTS OF WARM SURFACE TEMPERATURES
FROM 33 TO 38 DEGREES...ACCUMULATIONS WILL BE MINIMAL...NO MORE
THAN A TENTH OR TWO. THE EXCEPTION BEING ACROSS NORTH-CENTRAL
WISCONSIN WHERE UP TO AN ADDITIONAL INCH IS POSSIBLE DUE TO COOLER
TEMPERATURES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

MONDAY NIGHT THROUGH TUESDAY...THE SURFACE LOW EJECTS FROM CENTRAL
IOWA INTO THE WESTERN GREAT LAKES. WARM SURFACE TO 900 HPA LAYER
SURGES NORTHWARD ACROSS THE FORECAST AREA ALLOWING SNOW TUESDAY
MORNING TO CHANGE BACK OVER TO ALL RAIN IN THE AFTERNOON. HOWEVER...
SUB-FREEZING AIR MASS ACROSS CENTRAL MN/NORTHERN WI COULD RESULT
IN A RAIN/SNOW MIX ALONG AND NORTHWEST OF A LINE FROM MEDFORD TO
CHARLES CITY. ACCUMULATIONS TUESDAY WILL GENERALLY BE AN INCH OR
LESS IN THESE AREAS.

DRY SLOT WORKS ITS WAY INTO CENTRAL/SOUTHEAST WI TUESDAY NIGHT
INTO WEDNESDAY WITH DEFORMATION PRECIPITATION AXIS INITIALLY
ACROSS SOUTH-CENTRAL MN INTO NORTHWEST WI...THEN SLIDING ACROSS
THE FORECAST AREA WEDNESDAY NIGHT. COLUMN WILL BE COLD ENOUGH FOR
ALL SNOW...BUT MODELS SUGGEST HIGHEST QPF WILL FALL JUST NORTH
AND WEST OF THE FORECAST AREA. ADDITIONAL ACCUMULATIONS OF A FEW
TENTHS OF AN INCH POSSIBLE THROUGH WEDNESDAY REGION-WIDE.

FOR MONDAY THROUGH CHRISTMAS EVE...EXPECT SNOW AMOUNTS FROM 2 TO 4
INCHES ACROSS TAYLOR/CLARK COUNTIES...1 TO 2 INCHES ACROSS SOUTHEAST
MN INTO PORTIONS OF WESTERN WI AND LESS THAN AN INCH ACROSS
NORTHEAST IA INTO SOUTHWEST WI. THERMAL PROFILES DO NOT SUPPORT
FREEZING RAIN OR SLEET THROUGH THE EVENT.DESPITE LOWER SNOW
AMOUNTS...ROADS LIKELY TO BE SLICK AT TIMES THROUGHOUT THE PERIOD
SO PERSONS WITH HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO
THE LATEST WEATHER FORECASTS AND ROAD CONDITIONS.

CHRISTMAS DAY WILL BE MOSTLY CLOUDY BUT DRY WITH TEMPERATURES
RISING INTO THE MID 30S. CHRISTMAS NIGHT THROUGH FRIDAY...THERE IS
A CHANCE FOR ADDITIONAL SNOWFALL AS ANOTHER SURFACE LOW/WAVE ALOFT
SLICES THROUGH THE UPPER MIDWEST. THE UPCOMING WEEKEND WILL BE
DRY...BUT MUCH COLDER IN THE WAKE OF A STRONG COLD FRONT.
TEMPERATURES EACH DAY WILL ONLY RISE INTO THE TEENS TO LOWER 20S
WITH NIGHTTIME LOWS IN THE SINGLE DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1025 PM CST SUN DEC 21 2014

THE SOUTHERLY FLOW OF MOISTURE CONTINUES INTO THE TAF SITES...
RESULTING IN LIFR CEILINGS AT RST AND MVFR CEILINGS AT LSE.
VISIBILITIES HAVE BEEN BETTER THAN THE PAST FEW DAYS...
THOUGH...MVFR TO VFR. CONDITIONS LOOK TO LOWER SOME FOR THE EARLY
MORNING HOURS WITH THE AID OF NIGHTTIME COOLING...BUT THEN SHOULD
SLIGHTLY IMPROVE LATE IN THE MORNING WITH DAYTIME MIXING. AT THIS
TIME CONDITIONS APPEAR TO STAY STATUS QUO THEN THROUGH THE REST OF
THE DAY AS LIGHT RAIN GRADUALLY MOVES INTO THE SITES. SOME
LOWERING OF THE VISIBILITY TO IFR IS POSSIBLE AT RST IN THE
EVENING...DUE TO THE RAIN SWITCHING OVER TO SNOW FROM COOLER AIR
COMING IN.

REGARDING WINDS...EXPECT 10-20 KT WINDS TO PERSIST OVERNIGHT DUE
TO A TIGHT PRESSURE GRADIENT IN PLACE. ONSET OF DAYTIME MIXING
SHOULD CAUSE 20-25 KT GUSTS TO RETURN AT RST...WHICH THEN
DIMINISH LATE. DID NOT INCLUDE GUSTS AT LSE AS GRADIENT IS A
LITTLE WEAKER. WINDS LOOK TO BACK EASTERLY IN THE EVENING AND
DIMINISH AS LOW PRESSURE BEGINS TO MARCH NORTH TOWARDS THE AREA
FROM MISSOURI.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...AJ





000
FXUS63 KARX 220425
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1025 PM CST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

CHALLENGES ABOUND WITH UPCOMING WINTER STORM TONIGHT THROUGH
CHRISTMAS EVE...WITH PRIMARY CONCERNS BEING PRECIPITATION TYPE
AND AMOUNTS. SURFACE LOW TRACK AND TIMING FROM 21.12Z MODEL SUITE
IN REASONABLE AGREEMENT AND WITH FAIRLY SIMILAR THERMAL/MASS
PROFILES...WILL USE A BLENDED SOLUTION THAT MATCHES WELL WITH
LATEST WPC SNOW AMOUNTS.

FOR TONIGHT...LIGHT PRECIPITATION CURRENTLY ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE TO LIFT NORTHEAST UNDER
WEAK ISENTROPIC LIFT REGIME. EXTENDED DRIZZLE MENTION THROUGH
22.12Z AS SOUNDINGS SHOW A 3000 TO 5000 FT DRY LAYER IN THE MID-
LEVELS THAT SHOULD BE DEEP ENOUGH TO PRECLUDE THE SEEDER-FEEDER
PROCESS. ANY SNOW SHOULD BE MAINLY CONFINED TO TAYLOR/CLARK
COUNTIES WHERE SURFACE TEMPERATURES SHOULD HOVER ABOUT THE
FREEZING MARK. UP TO A HALF INCH ACCUMULATION IS POSSIBLE. ALSO
EXPECT AREAS OF FOG THROUGH THE NIGHT.

SURFACE LOW DROPS FROM SOUTHEAST SD AT 22.12Z INTO CENTRAL IOWA BY
23.12Z. WARM AIR ADVECTION/ISENTROPIC LIFT INDUCED PRECIPITATION
WILL LIFT NORTH AND EAST THROUGH THE DAY...SPREADING ACROSS THE
ENTIRE FORECAST AREA BY MONDAY AFTERNOON. MAXIMUM WEB-BULB
TEMPERATURE THROUGH THE COLUMN REMAINS WITHIN A DEGREE OF ZERO
CELSIUS ACROSS THE REGION. NEAR SURFACE TO 850 HPA LAYER
EVENTUALLY SATURATES ALONG AND JUST BELOW THE ZERO CELSIUS
ISOTHERM. WITH SURFACE TEMPERATURES GENERALLY IN THE MID 30S...
INTRODUCED PERIODS OF A RAIN/SNOW MIX THROUGH THE DAY. UNLESS
SNOWFALL RATE CAN EXCEED THE AFFECTS OF WARM SURFACE TEMPERATURES
FROM 33 TO 38 DEGREES...ACCUMULATIONS WILL BE MINIMAL...NO MORE
THAN A TENTH OR TWO. THE EXCEPTION BEING ACROSS NORTH-CENTRAL
WISCONSIN WHERE UP TO AN ADDITIONAL INCH IS POSSIBLE DUE TO COOLER
TEMPERATURES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

MONDAY NIGHT THROUGH TUESDAY...THE SURFACE LOW EJECTS FROM CENTRAL
IOWA INTO THE WESTERN GREAT LAKES. WARM SURFACE TO 900 HPA LAYER
SURGES NORTHWARD ACROSS THE FORECAST AREA ALLOWING SNOW TUESDAY
MORNING TO CHANGE BACK OVER TO ALL RAIN IN THE AFTERNOON. HOWEVER...
SUB-FREEZING AIR MASS ACROSS CENTRAL MN/NORTHERN WI COULD RESULT
IN A RAIN/SNOW MIX ALONG AND NORTHWEST OF A LINE FROM MEDFORD TO
CHARLES CITY. ACCUMULATIONS TUESDAY WILL GENERALLY BE AN INCH OR
LESS IN THESE AREAS.

DRY SLOT WORKS ITS WAY INTO CENTRAL/SOUTHEAST WI TUESDAY NIGHT
INTO WEDNESDAY WITH DEFORMATION PRECIPITATION AXIS INITIALLY
ACROSS SOUTH-CENTRAL MN INTO NORTHWEST WI...THEN SLIDING ACROSS
THE FORECAST AREA WEDNESDAY NIGHT. COLUMN WILL BE COLD ENOUGH FOR
ALL SNOW...BUT MODELS SUGGEST HIGHEST QPF WILL FALL JUST NORTH
AND WEST OF THE FORECAST AREA. ADDITIONAL ACCUMULATIONS OF A FEW
TENTHS OF AN INCH POSSIBLE THROUGH WEDNESDAY REGION-WIDE.

FOR MONDAY THROUGH CHRISTMAS EVE...EXPECT SNOW AMOUNTS FROM 2 TO 4
INCHES ACROSS TAYLOR/CLARK COUNTIES...1 TO 2 INCHES ACROSS SOUTHEAST
MN INTO PORTIONS OF WESTERN WI AND LESS THAN AN INCH ACROSS
NORTHEAST IA INTO SOUTHWEST WI. THERMAL PROFILES DO NOT SUPPORT
FREEZING RAIN OR SLEET THROUGH THE EVENT.DESPITE LOWER SNOW
AMOUNTS...ROADS LIKELY TO BE SLICK AT TIMES THROUGHOUT THE PERIOD
SO PERSONS WITH HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO
THE LATEST WEATHER FORECASTS AND ROAD CONDITIONS.

CHRISTMAS DAY WILL BE MOSTLY CLOUDY BUT DRY WITH TEMPERATURES
RISING INTO THE MID 30S. CHRISTMAS NIGHT THROUGH FRIDAY...THERE IS
A CHANCE FOR ADDITIONAL SNOWFALL AS ANOTHER SURFACE LOW/WAVE ALOFT
SLICES THROUGH THE UPPER MIDWEST. THE UPCOMING WEEKEND WILL BE
DRY...BUT MUCH COLDER IN THE WAKE OF A STRONG COLD FRONT.
TEMPERATURES EACH DAY WILL ONLY RISE INTO THE TEENS TO LOWER 20S
WITH NIGHTTIME LOWS IN THE SINGLE DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1025 PM CST SUN DEC 21 2014

THE SOUTHERLY FLOW OF MOISTURE CONTINUES INTO THE TAF SITES...
RESULTING IN LIFR CEILINGS AT RST AND MVFR CEILINGS AT LSE.
VISIBILITIES HAVE BEEN BETTER THAN THE PAST FEW DAYS...
THOUGH...MVFR TO VFR. CONDITIONS LOOK TO LOWER SOME FOR THE EARLY
MORNING HOURS WITH THE AID OF NIGHTTIME COOLING...BUT THEN SHOULD
SLIGHTLY IMPROVE LATE IN THE MORNING WITH DAYTIME MIXING. AT THIS
TIME CONDITIONS APPEAR TO STAY STATUS QUO THEN THROUGH THE REST OF
THE DAY AS LIGHT RAIN GRADUALLY MOVES INTO THE SITES. SOME
LOWERING OF THE VISIBILITY TO IFR IS POSSIBLE AT RST IN THE
EVENING...DUE TO THE RAIN SWITCHING OVER TO SNOW FROM COOLER AIR
COMING IN.

REGARDING WINDS...EXPECT 10-20 KT WINDS TO PERSIST OVERNIGHT DUE
TO A TIGHT PRESSURE GRADIENT IN PLACE. ONSET OF DAYTIME MIXING
SHOULD CAUSE 20-25 KT GUSTS TO RETURN AT RST...WHICH THEN
DIMINISH LATE. DID NOT INCLUDE GUSTS AT LSE AS GRADIENT IS A
LITTLE WEAKER. WINDS LOOK TO BACK EASTERLY IN THE EVENING AND
DIMINISH AS LOW PRESSURE BEGINS TO MARCH NORTH TOWARDS THE AREA
FROM MISSOURI.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...AJ




000
FXUS63 KARX 212324
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
524 PM CST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

CHALLENGES ABOUND WITH UPCOMING WINTER STORM TONIGHT THROUGH
CHRISTMAS EVE...WITH PRIMARY CONCERNS BEING PRECIPITATION TYPE
AND AMOUNTS. SURFACE LOW TRACK AND TIMING FROM 21.12Z MODEL SUITE
IN REASONABLE AGREEMENT AND WITH FAIRLY SIMILAR THERMAL/MASS
PROFILES...WILL USE A BLENDED SOLUTION THAT MATCHES WELL WITH
LATEST WPC SNOW AMOUNTS.

FOR TONIGHT...LIGHT PRECIPITATION CURRENTLY ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE TO LIFT NORTHEAST UNDER
WEAK ISENTROPIC LIFT REGIME. EXTENDED DRIZZLE MENTION THROUGH
22.12Z AS SOUNDINGS SHOW A 3000 TO 5000 FT DRY LAYER IN THE MID-
LEVELS THAT SHOULD BE DEEP ENOUGH TO PRECLUDE THE SEEDER-FEEDER
PROCESS. ANY SNOW SHOULD BE MAINLY CONFINED TO TAYLOR/CLARK
COUNTIES WHERE SURFACE TEMPERATURES SHOULD HOVER ABOUT THE
FREEZING MARK. UP TO A HALF INCH ACCUMULATION IS POSSIBLE. ALSO
EXPECT AREAS OF FOG THROUGH THE NIGHT.

SURFACE LOW DROPS FROM SOUTHEAST SD AT 22.12Z INTO CENTRAL IOWA BY
23.12Z. WARM AIR ADVECTION/ISENTROPIC LIFT INDUCED PRECIPITATION
WILL LIFT NORTH AND EAST THROUGH THE DAY...SPREADING ACROSS THE
ENTIRE FORECAST AREA BY MONDAY AFTERNOON. MAXIMUM WEB-BULB
TEMPERATURE THROUGH THE COLUMN REMAINS WITHIN A DEGREE OF ZERO
CELSIUS ACROSS THE REGION. NEAR SURFACE TO 850 HPA LAYER
EVENTUALLY SATURATES ALONG AND JUST BELOW THE ZERO CELSIUS
ISOTHERM. WITH SURFACE TEMPERATURES GENERALLY IN THE MID 30S...
INTRODUCED PERIODS OF A RAIN/SNOW MIX THROUGH THE DAY. UNLESS
SNOWFALL RATE CAN EXCEED THE AFFECTS OF WARM SURFACE TEMPERATURES
FROM 33 TO 38 DEGREES...ACCUMULATIONS WILL BE MINIMAL...NO MORE
THAN A TENTH OR TWO. THE EXCEPTION BEING ACROSS NORTH-CENTRAL
WISCONSIN WHERE UP TO AN ADDITIONAL INCH IS POSSIBLE DUE TO COOLER
TEMPERATURES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

MONDAY NIGHT THROUGH TUESDAY...THE SURFACE LOW EJECTS FROM CENTRAL
IOWA INTO THE WESTERN GREAT LAKES. WARM SURFACE TO 900 HPA LAYER
SURGES NORTHWARD ACROSS THE FORECAST AREA ALLOWING SNOW TUESDAY
MORNING TO CHANGE BACK OVER TO ALL RAIN IN THE AFTERNOON. HOWEVER...
SUB-FREEZING AIR MASS ACROSS CENTRAL MN/NORTHERN WI COULD RESULT
IN A RAIN/SNOW MIX ALONG AND NORTHWEST OF A LINE FROM MEDFORD TO
CHARLES CITY. ACCUMULATIONS TUESDAY WILL GENERALLY BE AN INCH OR
LESS IN THESE AREAS.

DRY SLOT WORKS ITS WAY INTO CENTRAL/SOUTHEAST WI TUESDAY NIGHT
INTO WEDNESDAY WITH DEFORMATION PRECIPITATION AXIS INITIALLY
ACROSS SOUTH-CENTRAL MN INTO NORTHWEST WI...THEN SLIDING ACROSS
THE FORECAST AREA WEDNESDAY NIGHT. COLUMN WILL BE COLD ENOUGH FOR
ALL SNOW...BUT MODELS SUGGEST HIGHEST QPF WILL FALL JUST NORTH
AND WEST OF THE FORECAST AREA. ADDITIONAL ACCUMULATIONS OF A FEW
TENTHS OF AN INCH POSSIBLE THROUGH WEDNESDAY REGION-WIDE.

FOR MONDAY THROUGH CHRISTMAS EVE...EXPECT SNOW AMOUNTS FROM 2 TO 4
INCHES ACROSS TAYLOR/CLARK COUNTIES...1 TO 2 INCHES ACROSS SOUTHEAST
MN INTO PORTIONS OF WESTERN WI AND LESS THAN AN INCH ACROSS
NORTHEAST IA INTO SOUTHWEST WI. THERMAL PROFILES DO NOT SUPPORT
FREEZING RAIN OR SLEET THROUGH THE EVENT.DESPITE LOWER SNOW
AMOUNTS...ROADS LIKELY TO BE SLICK AT TIMES THROUGHOUT THE PERIOD
SO PERSONS WITH HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO
THE LATEST WEATHER FORECASTS AND ROAD CONDITIONS.

CHRISTMAS DAY WILL BE MOSTLY CLOUDY BUT DRY WITH TEMPERATURES
RISING INTO THE MID 30S. CHRISTMAS NIGHT THROUGH FRIDAY...THERE IS
A CHANCE FOR ADDITIONAL SNOWFALL AS ANOTHER SURFACE LOW/WAVE ALOFT
SLICES THROUGH THE UPPER MIDWEST. THE UPCOMING WEEKEND WILL BE
DRY...BUT MUCH COLDER IN THE WAKE OF A STRONG COLD FRONT.
TEMPERATURES EACH DAY WILL ONLY RISE INTO THE TEENS TO LOWER 20S
WITH NIGHTTIME LOWS IN THE SINGLE DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 524 PM CST SUN DEC 21 2014

BREEZY SOUTHERLY FLOW...EXPECTED TO PERSIST THROUGH MONDAY WITH A
BACKING TOWARDS MORE EASTERLY LATE...CONTINUES TO BRING MORE AND
MORE MOISTURE INTO THE TAF SITES. THUS WE SHOULD SEE THE STRATUS
PERSIST. HOWEVER...HIGHER CEILINGS AND VISIBILITIES...MAINLY IN
THE MVFR RANGE...ARE PRESENT ACROSS EASTERN IOWA. THEREFORE...
HAVE TRENDED THE VISIBILITY FORECAST MORE OPTOMISTIC...ONLY
DROPPING TO IFR BETWEEN 06-15Z AT RST AND HOLDING AT MVFR AT LSE.
CEILINGS TOO COULD END UP MORE OPTOMISTIC...BUT A COLD GROUND AND
UPSLOPE FLOW AT RST MAY KEEP CEILINGS IN THE IFR/LIFR RANGE. THE
VALLEY SITE OF LSE PLUS MIXING FROM THE BREEZE SHOULD LIMIT THE
FALL TO PERHAPS IFR FROM NIGHTTIME COOLING LATE TONIGHT. CEILINGS
SHOULD RETURN TO MVFR AT LSE BY LATE MORNING.

ONLY OTHER ITEM TO NOTE IS ON PRECIPITATION TYPE. MOST OF THE
PRECIPITATION THROUGH MONDAY IS EXPECTED AS RAIN OR DRIZZLE.
HOWEVER...LATE MONDAY THERE IS A CHANCE THE PRECIPITATION COULD
SWITCH OVER TO SNOW AT RST. IF THIS OCCURS...VISIBILITIES OF IFR
ARE POSSIBLE.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...AJ




000
FXUS63 KARX 212324
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
524 PM CST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

CHALLENGES ABOUND WITH UPCOMING WINTER STORM TONIGHT THROUGH
CHRISTMAS EVE...WITH PRIMARY CONCERNS BEING PRECIPITATION TYPE
AND AMOUNTS. SURFACE LOW TRACK AND TIMING FROM 21.12Z MODEL SUITE
IN REASONABLE AGREEMENT AND WITH FAIRLY SIMILAR THERMAL/MASS
PROFILES...WILL USE A BLENDED SOLUTION THAT MATCHES WELL WITH
LATEST WPC SNOW AMOUNTS.

FOR TONIGHT...LIGHT PRECIPITATION CURRENTLY ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE TO LIFT NORTHEAST UNDER
WEAK ISENTROPIC LIFT REGIME. EXTENDED DRIZZLE MENTION THROUGH
22.12Z AS SOUNDINGS SHOW A 3000 TO 5000 FT DRY LAYER IN THE MID-
LEVELS THAT SHOULD BE DEEP ENOUGH TO PRECLUDE THE SEEDER-FEEDER
PROCESS. ANY SNOW SHOULD BE MAINLY CONFINED TO TAYLOR/CLARK
COUNTIES WHERE SURFACE TEMPERATURES SHOULD HOVER ABOUT THE
FREEZING MARK. UP TO A HALF INCH ACCUMULATION IS POSSIBLE. ALSO
EXPECT AREAS OF FOG THROUGH THE NIGHT.

SURFACE LOW DROPS FROM SOUTHEAST SD AT 22.12Z INTO CENTRAL IOWA BY
23.12Z. WARM AIR ADVECTION/ISENTROPIC LIFT INDUCED PRECIPITATION
WILL LIFT NORTH AND EAST THROUGH THE DAY...SPREADING ACROSS THE
ENTIRE FORECAST AREA BY MONDAY AFTERNOON. MAXIMUM WEB-BULB
TEMPERATURE THROUGH THE COLUMN REMAINS WITHIN A DEGREE OF ZERO
CELSIUS ACROSS THE REGION. NEAR SURFACE TO 850 HPA LAYER
EVENTUALLY SATURATES ALONG AND JUST BELOW THE ZERO CELSIUS
ISOTHERM. WITH SURFACE TEMPERATURES GENERALLY IN THE MID 30S...
INTRODUCED PERIODS OF A RAIN/SNOW MIX THROUGH THE DAY. UNLESS
SNOWFALL RATE CAN EXCEED THE AFFECTS OF WARM SURFACE TEMPERATURES
FROM 33 TO 38 DEGREES...ACCUMULATIONS WILL BE MINIMAL...NO MORE
THAN A TENTH OR TWO. THE EXCEPTION BEING ACROSS NORTH-CENTRAL
WISCONSIN WHERE UP TO AN ADDITIONAL INCH IS POSSIBLE DUE TO COOLER
TEMPERATURES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

MONDAY NIGHT THROUGH TUESDAY...THE SURFACE LOW EJECTS FROM CENTRAL
IOWA INTO THE WESTERN GREAT LAKES. WARM SURFACE TO 900 HPA LAYER
SURGES NORTHWARD ACROSS THE FORECAST AREA ALLOWING SNOW TUESDAY
MORNING TO CHANGE BACK OVER TO ALL RAIN IN THE AFTERNOON. HOWEVER...
SUB-FREEZING AIR MASS ACROSS CENTRAL MN/NORTHERN WI COULD RESULT
IN A RAIN/SNOW MIX ALONG AND NORTHWEST OF A LINE FROM MEDFORD TO
CHARLES CITY. ACCUMULATIONS TUESDAY WILL GENERALLY BE AN INCH OR
LESS IN THESE AREAS.

DRY SLOT WORKS ITS WAY INTO CENTRAL/SOUTHEAST WI TUESDAY NIGHT
INTO WEDNESDAY WITH DEFORMATION PRECIPITATION AXIS INITIALLY
ACROSS SOUTH-CENTRAL MN INTO NORTHWEST WI...THEN SLIDING ACROSS
THE FORECAST AREA WEDNESDAY NIGHT. COLUMN WILL BE COLD ENOUGH FOR
ALL SNOW...BUT MODELS SUGGEST HIGHEST QPF WILL FALL JUST NORTH
AND WEST OF THE FORECAST AREA. ADDITIONAL ACCUMULATIONS OF A FEW
TENTHS OF AN INCH POSSIBLE THROUGH WEDNESDAY REGION-WIDE.

FOR MONDAY THROUGH CHRISTMAS EVE...EXPECT SNOW AMOUNTS FROM 2 TO 4
INCHES ACROSS TAYLOR/CLARK COUNTIES...1 TO 2 INCHES ACROSS SOUTHEAST
MN INTO PORTIONS OF WESTERN WI AND LESS THAN AN INCH ACROSS
NORTHEAST IA INTO SOUTHWEST WI. THERMAL PROFILES DO NOT SUPPORT
FREEZING RAIN OR SLEET THROUGH THE EVENT.DESPITE LOWER SNOW
AMOUNTS...ROADS LIKELY TO BE SLICK AT TIMES THROUGHOUT THE PERIOD
SO PERSONS WITH HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO
THE LATEST WEATHER FORECASTS AND ROAD CONDITIONS.

CHRISTMAS DAY WILL BE MOSTLY CLOUDY BUT DRY WITH TEMPERATURES
RISING INTO THE MID 30S. CHRISTMAS NIGHT THROUGH FRIDAY...THERE IS
A CHANCE FOR ADDITIONAL SNOWFALL AS ANOTHER SURFACE LOW/WAVE ALOFT
SLICES THROUGH THE UPPER MIDWEST. THE UPCOMING WEEKEND WILL BE
DRY...BUT MUCH COLDER IN THE WAKE OF A STRONG COLD FRONT.
TEMPERATURES EACH DAY WILL ONLY RISE INTO THE TEENS TO LOWER 20S
WITH NIGHTTIME LOWS IN THE SINGLE DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 524 PM CST SUN DEC 21 2014

BREEZY SOUTHERLY FLOW...EXPECTED TO PERSIST THROUGH MONDAY WITH A
BACKING TOWARDS MORE EASTERLY LATE...CONTINUES TO BRING MORE AND
MORE MOISTURE INTO THE TAF SITES. THUS WE SHOULD SEE THE STRATUS
PERSIST. HOWEVER...HIGHER CEILINGS AND VISIBILITIES...MAINLY IN
THE MVFR RANGE...ARE PRESENT ACROSS EASTERN IOWA. THEREFORE...
HAVE TRENDED THE VISIBILITY FORECAST MORE OPTOMISTIC...ONLY
DROPPING TO IFR BETWEEN 06-15Z AT RST AND HOLDING AT MVFR AT LSE.
CEILINGS TOO COULD END UP MORE OPTOMISTIC...BUT A COLD GROUND AND
UPSLOPE FLOW AT RST MAY KEEP CEILINGS IN THE IFR/LIFR RANGE. THE
VALLEY SITE OF LSE PLUS MIXING FROM THE BREEZE SHOULD LIMIT THE
FALL TO PERHAPS IFR FROM NIGHTTIME COOLING LATE TONIGHT. CEILINGS
SHOULD RETURN TO MVFR AT LSE BY LATE MORNING.

ONLY OTHER ITEM TO NOTE IS ON PRECIPITATION TYPE. MOST OF THE
PRECIPITATION THROUGH MONDAY IS EXPECTED AS RAIN OR DRIZZLE.
HOWEVER...LATE MONDAY THERE IS A CHANCE THE PRECIPITATION COULD
SWITCH OVER TO SNOW AT RST. IF THIS OCCURS...VISIBILITIES OF IFR
ARE POSSIBLE.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...AJ





000
FXUS63 KARX 212056
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
256 PM CST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

CHALLENGES ABOUND WITH UPCOMING WINTER STORM TONIGHT THROUGH
CHRISTMAS EVE...WITH PRIMARY CONCERNS BEING PRECIPITATION TYPE
AND AMOUNTS. SURFACE LOW TRACK AND TIMING FROM 21.12Z MODEL SUITE
IN REASONABLE AGREEMENT AND WITH FAIRLY SIMILAR THERMAL/MASS
PROFILES...WILL USE A BLENDED SOLUTION THAT MATCHES WELL WITH
LATEST WPC SNOW AMOUNTS.

FOR TONIGHT...LIGHT PRECIPITATION CURRENTLY ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE TO LIFT NORTHEAST UNDER
WEAK ISENTROPIC LIFT REGIME. EXTENDED DRIZZLE MENTION THROUGH
22.12Z AS SOUNDINGS SHOW A 3000 TO 5000 FT DRY LAYER IN THE MID-
LEVELS THAT SHOULD BE DEEP ENOUGH TO PRECLUDE THE SEEDER-FEEDER
PROCESS. ANY SNOW SHOULD BE MAINLY CONFINED TO TAYLOR/CLARK
COUNTIES WHERE SURFACE TEMPERATURES SHOULD HOVER ABOUT THE
FREEZING MARK. UP TO A HALF INCH ACCUMULATION IS POSSIBLE. ALSO
EXPECT AREAS OF FOG THROUGH THE NIGHT.

SURFACE LOW DROPS FROM SOUTHEAST SD AT 22.12Z INTO CENTRAL IOWA BY
23.12Z. WARM AIR ADVECTION/ISENTROPIC LIFT INDUCED PRECIPITATION
WILL LIFT NORTH AND EAST THROUGH THE DAY...SPREADING ACROSS THE
ENTIRE FORECAST AREA BY MONDAY AFTERNOON. MAXIMUM WEB-BULB
TEMPERATURE THROUGH THE COLUMN REMAINS WITHIN A DEGREE OF ZERO
CELSIUS ACROSS THE REGION. NEAR SURFACE TO 850 HPA LAYER
EVENTUALLY SATURATES ALONG AND JUST BELOW THE ZERO CELSIUS
ISOTHERM. WITH SURFACE TEMPERATURES GENERALLY IN THE MID 30S...
INTRODUCED PERIODS OF A RAIN/SNOW MIX THROUGH THE DAY. UNLESS
SNOWFALL RATE CAN EXCEED THE AFFECTS OF WARM SURFACE TEMPERATURES
FROM 33 TO 38 DEGREES...ACCUMULATIONS WILL BE MINIMAL...NO MORE
THAN A TENTH OR TWO. THE EXCEPTION BEING ACROSS NORTH-CENTRAL
WISCONSIN WHERE UP TO AN ADDITIONAL INCH IS POSSIBLE DUE TO COOLER
TEMPERATURES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

MONDAY NIGHT THROUGH TUESDAY...THE SURFACE LOW EJECTS FROM CENTRAL
IOWA INTO THE WESTERN GREAT LAKES. WARM SURFACE TO 900 HPA LAYER
SURGES NORTHWARD ACROSS THE FORECAST AREA ALLOWING SNOW TUESDAY
MORNING TO CHANGE BACK OVER TO ALL RAIN IN THE AFTERNOON. HOWEVER...
SUB-FREEZING AIR MASS ACROSS CENTRAL MN/NORTHERN WI COULD RESULT
IN A RAIN/SNOW MIX ALONG AND NORTHWEST OF A LINE FROM MEDFORD TO
CHARLES CITY. ACCUMULATIONS TUESDAY WILL GENERALLY BE AN INCH OR
LESS IN THESE AREAS.

DRY SLOT WORKS ITS WAY INTO CENTRAL/SOUTHEAST WI TUESDAY NIGHT
INTO WEDNESDAY WITH DEFORMATION PRECIPITATION AXIS INITIALLY
ACROSS SOUTH-CENTRAL MN INTO NORTHWEST WI...THEN SLIDING ACROSS
THE FORECAST AREA WEDNESDAY NIGHT. COLUMN WILL BE COLD ENOUGH FOR
ALL SNOW...BUT MODELS SUGGEST HIGHEST QPF WILL FALL JUST NORTH
AND WEST OF THE FORECAST AREA. ADDITIONAL ACCUMULATIONS OF A FEW
TENTHS OF AN INCH POSSIBLE THROUGH WEDNESDAY REGION-WIDE.

FOR MONDAY THROUGH CHRISTMAS EVE...EXPECT SNOW AMOUNTS FROM 2 TO 4
INCHES ACROSS TAYLOR/CLARK COUNTIES...1 TO 2 INCHES ACROSS SOUTHEAST
MN INTO PORTIONS OF WESTERN WI AND LESS THAN AN INCH ACROSS
NORTHEAST IA INTO SOUTHWEST WI. THERMAL PROFILES DO NOT SUPPORT
FREEZING RAIN OR SLEET THROUGH THE EVENT.DESPITE LOWER SNOW
AMOUNTS...ROADS LIKELY TO BE SLICK AT TIMES THROUGHOUT THE PERIOD
SO PERSONS WITH HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO
THE LATEST WEATHER FORECASTS AND ROAD CONDITIONS.

CHRISTMAS DAY WILL BE MOSTLY CLOUDY BUT DRY WITH TEMPERATURES
RISING INTO THE MID 30S. CHRISTMAS NIGHT THROUGH FRIDAY...THERE IS
A CHANCE FOR ADDITIONAL SNOWFALL AS ANOTHER SURFACE LOW/WAVE ALOFT
SLICES THROUGH THE UPPER MIDWEST. THE UPCOMING WEEKEND WILL BE
DRY...BUT MUCH COLDER IN THE WAKE OF A STRONG COLD FRONT.
TEMPERATURES EACH DAY WILL ONLY RISE INTO THE TEENS TO LOWER 20S
WITH NIGHTTIME LOWS IN THE SINGLE DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1135 AM CST SUN DEC 21 2014

POOR AVIATION WEATHER TO CONTINUE WITH FAIRLY WIDESPREAD IFR
THROUGHOUT THE REGION. ALTHOUGH VISIBILITIES DID IMPROVE AS WARM
FRONT LIFTED NORTH...LOW CEILINGS AND INTERMITTENT LIGHT
PRECIPITATION WILL CONTINUE INTO MONDAY. TEMPERATURE PROFILE IS
CLOSE TO RAIN-SNOW LINE BUT BANKING ON CONDITIONS REMAINING WARM
ENOUGH NEAR GROUND LEVEL FOR MAINLY RAIN SO WILL NOT INTRODUCE MIX
AT TAF SITES YET. IF STEADIER RAIN DEVELOPS TONIGHT AS FORCING
INCREASES AHEAD OF SYSTEM...VISIBILITIES COULD IMPROVE AFTER SOME
DECREASE EARLY THIS EVENING BUT THAT WILL TAKE A LOT OF SHORT TERM
TWEAKING.


&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...SHEA





000
FXUS63 KARX 212056
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
256 PM CST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

CHALLENGES ABOUND WITH UPCOMING WINTER STORM TONIGHT THROUGH
CHRISTMAS EVE...WITH PRIMARY CONCERNS BEING PRECIPITATION TYPE
AND AMOUNTS. SURFACE LOW TRACK AND TIMING FROM 21.12Z MODEL SUITE
IN REASONABLE AGREEMENT AND WITH FAIRLY SIMILAR THERMAL/MASS
PROFILES...WILL USE A BLENDED SOLUTION THAT MATCHES WELL WITH
LATEST WPC SNOW AMOUNTS.

FOR TONIGHT...LIGHT PRECIPITATION CURRENTLY ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE TO LIFT NORTHEAST UNDER
WEAK ISENTROPIC LIFT REGIME. EXTENDED DRIZZLE MENTION THROUGH
22.12Z AS SOUNDINGS SHOW A 3000 TO 5000 FT DRY LAYER IN THE MID-
LEVELS THAT SHOULD BE DEEP ENOUGH TO PRECLUDE THE SEEDER-FEEDER
PROCESS. ANY SNOW SHOULD BE MAINLY CONFINED TO TAYLOR/CLARK
COUNTIES WHERE SURFACE TEMPERATURES SHOULD HOVER ABOUT THE
FREEZING MARK. UP TO A HALF INCH ACCUMULATION IS POSSIBLE. ALSO
EXPECT AREAS OF FOG THROUGH THE NIGHT.

SURFACE LOW DROPS FROM SOUTHEAST SD AT 22.12Z INTO CENTRAL IOWA BY
23.12Z. WARM AIR ADVECTION/ISENTROPIC LIFT INDUCED PRECIPITATION
WILL LIFT NORTH AND EAST THROUGH THE DAY...SPREADING ACROSS THE
ENTIRE FORECAST AREA BY MONDAY AFTERNOON. MAXIMUM WEB-BULB
TEMPERATURE THROUGH THE COLUMN REMAINS WITHIN A DEGREE OF ZERO
CELSIUS ACROSS THE REGION. NEAR SURFACE TO 850 HPA LAYER
EVENTUALLY SATURATES ALONG AND JUST BELOW THE ZERO CELSIUS
ISOTHERM. WITH SURFACE TEMPERATURES GENERALLY IN THE MID 30S...
INTRODUCED PERIODS OF A RAIN/SNOW MIX THROUGH THE DAY. UNLESS
SNOWFALL RATE CAN EXCEED THE AFFECTS OF WARM SURFACE TEMPERATURES
FROM 33 TO 38 DEGREES...ACCUMULATIONS WILL BE MINIMAL...NO MORE
THAN A TENTH OR TWO. THE EXCEPTION BEING ACROSS NORTH-CENTRAL
WISCONSIN WHERE UP TO AN ADDITIONAL INCH IS POSSIBLE DUE TO COOLER
TEMPERATURES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 256 PM CST SUN DEC 21 2014

MONDAY NIGHT THROUGH TUESDAY...THE SURFACE LOW EJECTS FROM CENTRAL
IOWA INTO THE WESTERN GREAT LAKES. WARM SURFACE TO 900 HPA LAYER
SURGES NORTHWARD ACROSS THE FORECAST AREA ALLOWING SNOW TUESDAY
MORNING TO CHANGE BACK OVER TO ALL RAIN IN THE AFTERNOON. HOWEVER...
SUB-FREEZING AIR MASS ACROSS CENTRAL MN/NORTHERN WI COULD RESULT
IN A RAIN/SNOW MIX ALONG AND NORTHWEST OF A LINE FROM MEDFORD TO
CHARLES CITY. ACCUMULATIONS TUESDAY WILL GENERALLY BE AN INCH OR
LESS IN THESE AREAS.

DRY SLOT WORKS ITS WAY INTO CENTRAL/SOUTHEAST WI TUESDAY NIGHT
INTO WEDNESDAY WITH DEFORMATION PRECIPITATION AXIS INITIALLY
ACROSS SOUTH-CENTRAL MN INTO NORTHWEST WI...THEN SLIDING ACROSS
THE FORECAST AREA WEDNESDAY NIGHT. COLUMN WILL BE COLD ENOUGH FOR
ALL SNOW...BUT MODELS SUGGEST HIGHEST QPF WILL FALL JUST NORTH
AND WEST OF THE FORECAST AREA. ADDITIONAL ACCUMULATIONS OF A FEW
TENTHS OF AN INCH POSSIBLE THROUGH WEDNESDAY REGION-WIDE.

FOR MONDAY THROUGH CHRISTMAS EVE...EXPECT SNOW AMOUNTS FROM 2 TO 4
INCHES ACROSS TAYLOR/CLARK COUNTIES...1 TO 2 INCHES ACROSS SOUTHEAST
MN INTO PORTIONS OF WESTERN WI AND LESS THAN AN INCH ACROSS
NORTHEAST IA INTO SOUTHWEST WI. THERMAL PROFILES DO NOT SUPPORT
FREEZING RAIN OR SLEET THROUGH THE EVENT.DESPITE LOWER SNOW
AMOUNTS...ROADS LIKELY TO BE SLICK AT TIMES THROUGHOUT THE PERIOD
SO PERSONS WITH HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO
THE LATEST WEATHER FORECASTS AND ROAD CONDITIONS.

CHRISTMAS DAY WILL BE MOSTLY CLOUDY BUT DRY WITH TEMPERATURES
RISING INTO THE MID 30S. CHRISTMAS NIGHT THROUGH FRIDAY...THERE IS
A CHANCE FOR ADDITIONAL SNOWFALL AS ANOTHER SURFACE LOW/WAVE ALOFT
SLICES THROUGH THE UPPER MIDWEST. THE UPCOMING WEEKEND WILL BE
DRY...BUT MUCH COLDER IN THE WAKE OF A STRONG COLD FRONT.
TEMPERATURES EACH DAY WILL ONLY RISE INTO THE TEENS TO LOWER 20S
WITH NIGHTTIME LOWS IN THE SINGLE DIGITS TO LOWER TEENS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1135 AM CST SUN DEC 21 2014

POOR AVIATION WEATHER TO CONTINUE WITH FAIRLY WIDESPREAD IFR
THROUGHOUT THE REGION. ALTHOUGH VISIBILITIES DID IMPROVE AS WARM
FRONT LIFTED NORTH...LOW CEILINGS AND INTERMITTENT LIGHT
PRECIPITATION WILL CONTINUE INTO MONDAY. TEMPERATURE PROFILE IS
CLOSE TO RAIN-SNOW LINE BUT BANKING ON CONDITIONS REMAINING WARM
ENOUGH NEAR GROUND LEVEL FOR MAINLY RAIN SO WILL NOT INTRODUCE MIX
AT TAF SITES YET. IF STEADIER RAIN DEVELOPS TONIGHT AS FORCING
INCREASES AHEAD OF SYSTEM...VISIBILITIES COULD IMPROVE AFTER SOME
DECREASE EARLY THIS EVENING BUT THAT WILL TAKE A LOT OF SHORT TERM
TWEAKING.


&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...SHEA




000
FXUS63 KARX 211735
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1135 AM CST SUN DEC 21 2014

.UPDATE...
ISSUED AT 1135 AM CST SUN DEC 21 2014

WARM FRONT CONTINUES TO PUSH NORTH AND WITH THAT VISIBILITIES HAVE
BEEN IMPROVING AS WELL. HAVE CLEARED DENSE FOG ADVISORY FROM AREA
WITH LITTLE IMPACT EXPECTED REST OF DAY.

MEANWHILE NORTH OF INTERSTATE 94 UPGLIDE OVER FRONT WILL LEAD TO
FURTHER ENHANCEMENT OF LIGHT PRECIPITATION TODAY. NO WARM LAYER
ALOFT WILL MEAN FAIRLY DISTINCT RAIN-SNOW LINE AND OBSERVATIONS SEEM
TO REFLECT THAT. SHORT TERM GUIDANCE ALL SUGGESTS PRECIPITATION
EXPANDING IN THAT AREA AS WELL SO WOULD NOT BE SURPRISED WITH MINOR
ACCUMULATIONS...ESPECIALLY NORTH OF HIGHWAY 29 IN WISCONSIN.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CST SUN DEC 21 2014

THE MAIN FOCUS IS WITH THE DENSE FOG THIS MORNING ALONG WITH THE
DEVELOPING PRECIPITATION TODAY INTO TONIGHT.

DENSE FOG HAS FORMED ALONG AND NORTH OF A WARM FRONT THAT EXTENDS
EAST FROM THE SIOUX FALLS AREA ALONG THE IOWA/MINNESOTA BORDER
THEN RUNS SOUTHEAST INTO NORTHERN ILLINOIS. OBSERVATIONS IN
NORTHEAST IOWA ARE STILL SHOWING 1/4SM...SO PLAN TO LET THE
ADVISORY CONTINUE THROUGH THE MORNING OR UNTIL CONDITIONS IMPROVE.
THE 21.06Z HRRR/RAP SHOW THIS WARM FRONT ADVANCING NORTHWARD THIS
MORNING WITH THE BAND OF LOWEST VISIBILITIES ALSO LIFTING NORTH
AND DIMINISHING AS THE MORNING GOES ON. WILL HAVE TO KEEP AN EYE
ON OBS THROUGH THE MORNING FOR WHETHER THE ADVISORY CAN BE EXPIRED
EARLY.

GOING INTO THIS AFTERNOON...THERE HAS BEEN A FAIRLY CONSISTENT
MESSAGE OF PRECIPITATION DEVELOPING AS A 700MB TROUGH CATCHES UP
TO THE LOW LEVEL WARM AIR ADVECTION. THE HIGHEST CHANCES FOR THIS
PRECIPITATION CONTINUES TO BE ACROSS NORTHERN WISCONSIN WHERE THE
LIFT/MOISTURE WILL BE DEEPEST. THERMAL PROFILES LOOK COLD ENOUGH
TO SUPPORT ALL SNOW AT LEAST INITIALLY BEFORE THE WARM SECTOR
LIFTS NORTH TONIGHT. WITH ABOUT A TENTH OF AN INCH OF QPF AND SNOW
RATIOS AROUND 8:1 OR SO...AM EXPECTING A QUICK INCH OF SNOW IN
CLARK/TAYLOR COUNTIES THIS AFTERNOON WITH AREAS TO THE SOUTH
LIKELY SEEING MORE OF A DRIZZLE/RAIN SITUATION.

THE MAIN QUESTION WITH THIS PRECIPITATION IS WITH A DRY LAYER THAT
SHOWS UP ON 21.00Z NAM/GFS/RAP SOUNDINGS AROUND 800-700MB AND
WHETHER THAT COLUMN WILL BE SMALL ENOUGH FOR SEEDER-FEEDER TO
WORK. ALSO...SURFACE TEMPERATURES WILL BE ABOVE FREEZING...SO THIS
COMBINED WITH HOW DRY THE COLUMN IS LEADS TO SOME QUESTIONS WITH
PRECIPITATION TYPE. WITH FORCING RELATIVELY WEAK...EXPECT THAT THE
DRY LAYER WILL BE DEEP ENOUGH TO KEEP PRECIPITATION MORE AS
RAIN/DRIZZLE...PARTICULARLY WITH THE ABOVE FREEZING NEAR SURFACE
LAYER.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CST SUN DEC 21 2014

FAIRLY GOOD CONSENSUS AMONGST THE GUIDANCE WITH BRINGING THE MAIN
BAND OF PRECIPITATION THROUGH ON MONDAY INTO MONDAY EVENING AS THE
CLOSED MID LEVEL LOW APPROACHES AND A LEAD SHORTWAVE TROUGH LIFTS
NORTHWARD AHEAD OF IT. HAVE MAINLY GONE WITH RAIN AS THE
PRECIPITATION TYPE FOR MONDAY...BUT CONFIDENCE IS NOT VERY HIGH
WITH THIS AS FORECAST SOUNDINGS FROM THE 21.00Z NAM/GFS ONLY SHOW
THE WARM LAYER GETTING TO 1 TO 2C ABOVE FREEZING...IF THAT. 21.03Z
SREF PROBABILITIES SHOW MAINLY RAIN WITH THE EXCEPTION OF NORTHERN
WISCONSIN. IF IT IS NOT ALL RAIN...COULD BE SOME SLEET OR SNOW
THAT MIXES IN THERE AS WELL.

AFTER THE INITIAL BAND MOVES THROUGH BY MONDAY EVENING...THE
NAM/GFS SHOW THE DRY SLOW MOVING IN WHILE THE ECMWF SHOWS A
HEAVIER BAND OF RAIN/SNOW DEVELOPING NORTH OF A SURFACE LOW
TRACKING TO THE NORTH ALONG THE MISSISSIPPI. THE ECMWF THEN
DEVELOPS A DEEPER SURFACE LOW BY TUESDAY AFTERNOON COMPARED TO THE
NAM/GFS. SHOULD THE ECMWF SOLUTION BE THE TREND...WILL HAVE TO
PUSH PRECIPITATION CHANCES/AMOUNTS UP MORE THAN WHAT THEY
CURRENTLY ARE AT.

THE NEXT FEATURE OF NOTE IS WITH A PHASING MID LEVEL TROUGH THAT
LOOKS LIKE IT WILL BRING A BAND OF LIGHT SNOW IN ON THURSDAY
EVENING INTO FRIDAY MORNING. COULD SEE AN INCH OR TWO OF
ACCUMULATION FROM THIS SYSTEM WITH THE 21.00Z GFS/ECMWF NOT TOO
FAR OFF FROM EACH OTHER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1135 AM CST SUN DEC 21 2014

POOR AVIATION WEATHER TO CONTINUE WITH FAIRLY WIDESPREAD IFR
THROUGHOUT THE REGION. ALTHOUGH VISIBILITIES DID IMPROVE AS WARM
FRONT LIFTED NORTH...LOW CEILINGS AND INTERMITTENT LIGHT
PRECIPITATION WILL CONTINUE INTO MONDAY. TEMPERATURE PROFILE IS
CLOSE TO RAIN-SNOW LINE BUT BANKING ON CONDITIONS REMAINING WARM
ENOUGH NEAR GROUND LEVEL FOR MAINLY RAIN SO WILL NOT INTRODUCE MIX
AT TAF SITES YET. IF STEADIER RAIN DEVELOPS TONIGHT AS FORCING
INCREASES AHEAD OF SYSTEM...VISIBILITIES COULD IMPROVE AFTER SOME
DECREASE EARLY THIS EVENING BUT THAT WILL TAKE A LOT OF SHORT TERM
TWEEKING.

&&

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

&&

$$

UPDATE...SHEA
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...SHEA





000
FXUS63 KARX 211735
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1135 AM CST SUN DEC 21 2014

.UPDATE...
ISSUED AT 1135 AM CST SUN DEC 21 2014

WARM FRONT CONTINUES TO PUSH NORTH AND WITH THAT VISIBILITIES HAVE
BEEN IMPROVING AS WELL. HAVE CLEARED DENSE FOG ADVISORY FROM AREA
WITH LITTLE IMPACT EXPECTED REST OF DAY.

MEANWHILE NORTH OF INTERSTATE 94 UPGLIDE OVER FRONT WILL LEAD TO
FURTHER ENHANCEMENT OF LIGHT PRECIPITATION TODAY. NO WARM LAYER
ALOFT WILL MEAN FAIRLY DISTINCT RAIN-SNOW LINE AND OBSERVATIONS SEEM
TO REFLECT THAT. SHORT TERM GUIDANCE ALL SUGGESTS PRECIPITATION
EXPANDING IN THAT AREA AS WELL SO WOULD NOT BE SURPRISED WITH MINOR
ACCUMULATIONS...ESPECIALLY NORTH OF HIGHWAY 29 IN WISCONSIN.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CST SUN DEC 21 2014

THE MAIN FOCUS IS WITH THE DENSE FOG THIS MORNING ALONG WITH THE
DEVELOPING PRECIPITATION TODAY INTO TONIGHT.

DENSE FOG HAS FORMED ALONG AND NORTH OF A WARM FRONT THAT EXTENDS
EAST FROM THE SIOUX FALLS AREA ALONG THE IOWA/MINNESOTA BORDER
THEN RUNS SOUTHEAST INTO NORTHERN ILLINOIS. OBSERVATIONS IN
NORTHEAST IOWA ARE STILL SHOWING 1/4SM...SO PLAN TO LET THE
ADVISORY CONTINUE THROUGH THE MORNING OR UNTIL CONDITIONS IMPROVE.
THE 21.06Z HRRR/RAP SHOW THIS WARM FRONT ADVANCING NORTHWARD THIS
MORNING WITH THE BAND OF LOWEST VISIBILITIES ALSO LIFTING NORTH
AND DIMINISHING AS THE MORNING GOES ON. WILL HAVE TO KEEP AN EYE
ON OBS THROUGH THE MORNING FOR WHETHER THE ADVISORY CAN BE EXPIRED
EARLY.

GOING INTO THIS AFTERNOON...THERE HAS BEEN A FAIRLY CONSISTENT
MESSAGE OF PRECIPITATION DEVELOPING AS A 700MB TROUGH CATCHES UP
TO THE LOW LEVEL WARM AIR ADVECTION. THE HIGHEST CHANCES FOR THIS
PRECIPITATION CONTINUES TO BE ACROSS NORTHERN WISCONSIN WHERE THE
LIFT/MOISTURE WILL BE DEEPEST. THERMAL PROFILES LOOK COLD ENOUGH
TO SUPPORT ALL SNOW AT LEAST INITIALLY BEFORE THE WARM SECTOR
LIFTS NORTH TONIGHT. WITH ABOUT A TENTH OF AN INCH OF QPF AND SNOW
RATIOS AROUND 8:1 OR SO...AM EXPECTING A QUICK INCH OF SNOW IN
CLARK/TAYLOR COUNTIES THIS AFTERNOON WITH AREAS TO THE SOUTH
LIKELY SEEING MORE OF A DRIZZLE/RAIN SITUATION.

THE MAIN QUESTION WITH THIS PRECIPITATION IS WITH A DRY LAYER THAT
SHOWS UP ON 21.00Z NAM/GFS/RAP SOUNDINGS AROUND 800-700MB AND
WHETHER THAT COLUMN WILL BE SMALL ENOUGH FOR SEEDER-FEEDER TO
WORK. ALSO...SURFACE TEMPERATURES WILL BE ABOVE FREEZING...SO THIS
COMBINED WITH HOW DRY THE COLUMN IS LEADS TO SOME QUESTIONS WITH
PRECIPITATION TYPE. WITH FORCING RELATIVELY WEAK...EXPECT THAT THE
DRY LAYER WILL BE DEEP ENOUGH TO KEEP PRECIPITATION MORE AS
RAIN/DRIZZLE...PARTICULARLY WITH THE ABOVE FREEZING NEAR SURFACE
LAYER.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CST SUN DEC 21 2014

FAIRLY GOOD CONSENSUS AMONGST THE GUIDANCE WITH BRINGING THE MAIN
BAND OF PRECIPITATION THROUGH ON MONDAY INTO MONDAY EVENING AS THE
CLOSED MID LEVEL LOW APPROACHES AND A LEAD SHORTWAVE TROUGH LIFTS
NORTHWARD AHEAD OF IT. HAVE MAINLY GONE WITH RAIN AS THE
PRECIPITATION TYPE FOR MONDAY...BUT CONFIDENCE IS NOT VERY HIGH
WITH THIS AS FORECAST SOUNDINGS FROM THE 21.00Z NAM/GFS ONLY SHOW
THE WARM LAYER GETTING TO 1 TO 2C ABOVE FREEZING...IF THAT. 21.03Z
SREF PROBABILITIES SHOW MAINLY RAIN WITH THE EXCEPTION OF NORTHERN
WISCONSIN. IF IT IS NOT ALL RAIN...COULD BE SOME SLEET OR SNOW
THAT MIXES IN THERE AS WELL.

AFTER THE INITIAL BAND MOVES THROUGH BY MONDAY EVENING...THE
NAM/GFS SHOW THE DRY SLOW MOVING IN WHILE THE ECMWF SHOWS A
HEAVIER BAND OF RAIN/SNOW DEVELOPING NORTH OF A SURFACE LOW
TRACKING TO THE NORTH ALONG THE MISSISSIPPI. THE ECMWF THEN
DEVELOPS A DEEPER SURFACE LOW BY TUESDAY AFTERNOON COMPARED TO THE
NAM/GFS. SHOULD THE ECMWF SOLUTION BE THE TREND...WILL HAVE TO
PUSH PRECIPITATION CHANCES/AMOUNTS UP MORE THAN WHAT THEY
CURRENTLY ARE AT.

THE NEXT FEATURE OF NOTE IS WITH A PHASING MID LEVEL TROUGH THAT
LOOKS LIKE IT WILL BRING A BAND OF LIGHT SNOW IN ON THURSDAY
EVENING INTO FRIDAY MORNING. COULD SEE AN INCH OR TWO OF
ACCUMULATION FROM THIS SYSTEM WITH THE 21.00Z GFS/ECMWF NOT TOO
FAR OFF FROM EACH OTHER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1135 AM CST SUN DEC 21 2014

POOR AVIATION WEATHER TO CONTINUE WITH FAIRLY WIDESPREAD IFR
THROUGHOUT THE REGION. ALTHOUGH VISIBILITIES DID IMPROVE AS WARM
FRONT LIFTED NORTH...LOW CEILINGS AND INTERMITTENT LIGHT
PRECIPITATION WILL CONTINUE INTO MONDAY. TEMPERATURE PROFILE IS
CLOSE TO RAIN-SNOW LINE BUT BANKING ON CONDITIONS REMAINING WARM
ENOUGH NEAR GROUND LEVEL FOR MAINLY RAIN SO WILL NOT INTRODUCE MIX
AT TAF SITES YET. IF STEADIER RAIN DEVELOPS TONIGHT AS FORCING
INCREASES AHEAD OF SYSTEM...VISIBILITIES COULD IMPROVE AFTER SOME
DECREASE EARLY THIS EVENING BUT THAT WILL TAKE A LOT OF SHORT TERM
TWEEKING.

&&

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

&&

$$

UPDATE...SHEA
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...SHEA




000
FXUS63 KARX 211132
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
532 AM CST SUN DEC 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CST SUN DEC 21 2014

THE MAIN FOCUS IS WITH THE DENSE FOG THIS MORNING ALONG WITH THE
DEVELOPING PRECIPITATION TODAY INTO TONIGHT.

DENSE FOG HAS FORMED ALONG AND NORTH OF A WARM FRONT THAT EXTENDS
EAST FROM THE SIOUX FALLS AREA ALONG THE IOWA/MINNESOTA BORDER
THEN RUNS SOUTHEAST INTO NORTHERN ILLINOIS. OBSERVATIONS IN
NORTHEAST IOWA ARE STILL SHOWING 1/4SM...SO PLAN TO LET THE
ADVISORY CONTINUE THROUGH THE MORNING OR UNTIL CONDITIONS IMPROVE.
THE 21.06Z HRRR/RAP SHOW THIS WARM FRONT ADVANCING NORTHWARD THIS
MORNING WITH THE BAND OF LOWEST VISIBILITIES ALSO LIFTING NORTH
AND DIMINISHING AS THE MORNING GOES ON. WILL HAVE TO KEEP AN EYE
ON OBS THROUGH THE MORNING FOR WHETHER THE ADVISORY CAN BE EXPIRED
EARLY.

GOING INTO THIS AFTERNOON...THERE HAS BEEN A FAIRLY CONSISTENT
MESSAGE OF PRECIPITATION DEVELOPING AS A 700MB TROUGH CATCHES UP
TO THE LOW LEVEL WARM AIR ADVECTION. THE HIGHEST CHANCES FOR THIS
PRECIPITATION CONTINUES TO BE ACROSS NORTHERN WISCONSIN WHERE THE
LIFT/MOISTURE WILL BE DEEPEST. THERMAL PROFILES LOOK COLD ENOUGH
TO SUPPORT ALL SNOW AT LEAST INITIALLY BEFORE THE WARM SECTOR
LIFTS NORTH TONIGHT. WITH ABOUT A TENTH OF AN INCH OF QPF AND SNOW
RATIOS AROUND 8:1 OR SO...AM EXPECTING A QUICK INCH OF SNOW IN
CLARK/TAYLOR COUNTIES THIS AFTERNOON WITH AREAS TO THE SOUTH
LIKELY SEEING MORE OF A DRIZZLE/RAIN SITUATION.

THE MAIN QUESTION WITH THIS PRECIPITATION IS WITH A DRY LAYER THAT
SHOWS UP ON 21.00Z NAM/GFS/RAP SOUNDINGS AROUND 800-700MB AND
WHETHER THAT COLUMN WILL BE SMALL ENOUGH FOR SEEDER-FEEDER TO
WORK. ALSO...SURFACE TEMPERATURES WILL BE ABOVE FREEZING...SO THIS
COMBINED WITH HOW DRY THE COLUMN IS LEADS TO SOME QUESTIONS WITH
PRECIPITATION TYPE. WITH FORCING RELATIVELY WEAK...EXPECT THAT THE
DRY LAYER WILL BE DEEP ENOUGH TO KEEP PRECIPITATION MORE AS
RAIN/DRIZZLE...PARTICULARLY WITH THE ABOVE FREEZING NEAR SURFACE
LAYER.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CST SUN DEC 21 2014

FAIRLY GOOD CONSENSUS AMONGST THE GUIDANCE WITH BRINGING THE MAIN
BAND OF PRECIPITATION THROUGH ON MONDAY INTO MONDAY EVENING AS THE
CLOSED MID LEVEL LOW APPROACHES AND A LEAD SHORTWAVE TROUGH LIFTS
NORTHWARD AHEAD OF IT. HAVE MAINLY GONE WITH RAIN AS THE
PRECIPITATION TYPE FOR MONDAY...BUT CONFIDENCE IS NOT VERY HIGH
WITH THIS AS FORECAST SOUNDINGS FROM THE 21.00Z NAM/GFS ONLY SHOW
THE WARM LAYER GETTING TO 1 TO 2C ABOVE FREEZING...IF THAT. 21.03Z
SREF PROBABILITIES SHOW MAINLY RAIN WITH THE EXCEPTION OF NORTHERN
WISCONSIN. IF IT IS NOT ALL RAIN...COULD BE SOME SLEET OR SNOW
THAT MIXES IN THERE AS WELL.

AFTER THE INITIAL BAND MOVES THROUGH BY MONDAY EVENING...THE
NAM/GFS SHOW THE DRY SLOW MOVING IN WHILE THE ECMWF SHOWS A
HEAVIER BAND OF RAIN/SNOW DEVELOPING NORTH OF A SURFACE LOW
TRACKING TO THE NORTH ALONG THE MISSISSIPPI. THE ECMWF THEN
DEVELOPS A DEEPER SURFACE LOW BY TUESDAY AFTERNOON COMPARED TO THE
NAM/GFS. SHOULD THE ECMWF SOLUTION BE THE TREND...WILL HAVE TO
PUSH PRECIPITATION CHANCES/AMOUNTS UP MORE THAN WHAT THEY
CURRENTLY ARE AT.

THE NEXT FEATURE OF NOTE IS WITH A PHASING MID LEVEL TROUGH THAT
LOOKS LIKE IT WILL BRING A BAND OF LIGHT SNOW IN ON THURSDAY
EVENING INTO FRIDAY MORNING. COULD SEE AN INCH OR TWO OF
ACCUMULATION FROM THIS SYSTEM WITH THE 21.00Z GFS/ECMWF NOT TOO
FAR OFF FROM EACH OTHER.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 532 AM CST SUN DEC 21 2014

A WARM FRONT LIFTING NORTHWARD ACROSS THE REGION WILL CONTINUE TO
PRODUCE EXTENSIVE IFR/LIFR CONDITIONS THROUGH THE NEXT 24 HOURS.
MAY BE BRIEF BREAKS INTO MVFR AT KLSE BETWEEN 17Z-02Z. LOOKING
FOR SOME PERIODS OF DRIZZLE THROUGH THE DAY AS WELL AND THEN
LOOKING AT RAIN MOVING INTO THE AREA AFTER 06Z TONIGHT AS LOW
PRESSURE APPROACHES FROM THE NORTHERN PLAINS. OTHERWISE...
TIGHTENING PRESSURE GRADIENT IN ADVANCE OF THE APPROACHING LOW
WILL PRODUCE SOUTH WINDS AROUND 10KT AT KLSE AND IN THE 10-20KT
RANGE AT KRST.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ086-087-
     094-095.

IA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR IAZ008>011-
     018-019-029-030.

&&

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS





000
FXUS63 KARX 211132
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
532 AM CST SUN DEC 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CST SUN DEC 21 2014

THE MAIN FOCUS IS WITH THE DENSE FOG THIS MORNING ALONG WITH THE
DEVELOPING PRECIPITATION TODAY INTO TONIGHT.

DENSE FOG HAS FORMED ALONG AND NORTH OF A WARM FRONT THAT EXTENDS
EAST FROM THE SIOUX FALLS AREA ALONG THE IOWA/MINNESOTA BORDER
THEN RUNS SOUTHEAST INTO NORTHERN ILLINOIS. OBSERVATIONS IN
NORTHEAST IOWA ARE STILL SHOWING 1/4SM...SO PLAN TO LET THE
ADVISORY CONTINUE THROUGH THE MORNING OR UNTIL CONDITIONS IMPROVE.
THE 21.06Z HRRR/RAP SHOW THIS WARM FRONT ADVANCING NORTHWARD THIS
MORNING WITH THE BAND OF LOWEST VISIBILITIES ALSO LIFTING NORTH
AND DIMINISHING AS THE MORNING GOES ON. WILL HAVE TO KEEP AN EYE
ON OBS THROUGH THE MORNING FOR WHETHER THE ADVISORY CAN BE EXPIRED
EARLY.

GOING INTO THIS AFTERNOON...THERE HAS BEEN A FAIRLY CONSISTENT
MESSAGE OF PRECIPITATION DEVELOPING AS A 700MB TROUGH CATCHES UP
TO THE LOW LEVEL WARM AIR ADVECTION. THE HIGHEST CHANCES FOR THIS
PRECIPITATION CONTINUES TO BE ACROSS NORTHERN WISCONSIN WHERE THE
LIFT/MOISTURE WILL BE DEEPEST. THERMAL PROFILES LOOK COLD ENOUGH
TO SUPPORT ALL SNOW AT LEAST INITIALLY BEFORE THE WARM SECTOR
LIFTS NORTH TONIGHT. WITH ABOUT A TENTH OF AN INCH OF QPF AND SNOW
RATIOS AROUND 8:1 OR SO...AM EXPECTING A QUICK INCH OF SNOW IN
CLARK/TAYLOR COUNTIES THIS AFTERNOON WITH AREAS TO THE SOUTH
LIKELY SEEING MORE OF A DRIZZLE/RAIN SITUATION.

THE MAIN QUESTION WITH THIS PRECIPITATION IS WITH A DRY LAYER THAT
SHOWS UP ON 21.00Z NAM/GFS/RAP SOUNDINGS AROUND 800-700MB AND
WHETHER THAT COLUMN WILL BE SMALL ENOUGH FOR SEEDER-FEEDER TO
WORK. ALSO...SURFACE TEMPERATURES WILL BE ABOVE FREEZING...SO THIS
COMBINED WITH HOW DRY THE COLUMN IS LEADS TO SOME QUESTIONS WITH
PRECIPITATION TYPE. WITH FORCING RELATIVELY WEAK...EXPECT THAT THE
DRY LAYER WILL BE DEEP ENOUGH TO KEEP PRECIPITATION MORE AS
RAIN/DRIZZLE...PARTICULARLY WITH THE ABOVE FREEZING NEAR SURFACE
LAYER.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CST SUN DEC 21 2014

FAIRLY GOOD CONSENSUS AMONGST THE GUIDANCE WITH BRINGING THE MAIN
BAND OF PRECIPITATION THROUGH ON MONDAY INTO MONDAY EVENING AS THE
CLOSED MID LEVEL LOW APPROACHES AND A LEAD SHORTWAVE TROUGH LIFTS
NORTHWARD AHEAD OF IT. HAVE MAINLY GONE WITH RAIN AS THE
PRECIPITATION TYPE FOR MONDAY...BUT CONFIDENCE IS NOT VERY HIGH
WITH THIS AS FORECAST SOUNDINGS FROM THE 21.00Z NAM/GFS ONLY SHOW
THE WARM LAYER GETTING TO 1 TO 2C ABOVE FREEZING...IF THAT. 21.03Z
SREF PROBABILITIES SHOW MAINLY RAIN WITH THE EXCEPTION OF NORTHERN
WISCONSIN. IF IT IS NOT ALL RAIN...COULD BE SOME SLEET OR SNOW
THAT MIXES IN THERE AS WELL.

AFTER THE INITIAL BAND MOVES THROUGH BY MONDAY EVENING...THE
NAM/GFS SHOW THE DRY SLOW MOVING IN WHILE THE ECMWF SHOWS A
HEAVIER BAND OF RAIN/SNOW DEVELOPING NORTH OF A SURFACE LOW
TRACKING TO THE NORTH ALONG THE MISSISSIPPI. THE ECMWF THEN
DEVELOPS A DEEPER SURFACE LOW BY TUESDAY AFTERNOON COMPARED TO THE
NAM/GFS. SHOULD THE ECMWF SOLUTION BE THE TREND...WILL HAVE TO
PUSH PRECIPITATION CHANCES/AMOUNTS UP MORE THAN WHAT THEY
CURRENTLY ARE AT.

THE NEXT FEATURE OF NOTE IS WITH A PHASING MID LEVEL TROUGH THAT
LOOKS LIKE IT WILL BRING A BAND OF LIGHT SNOW IN ON THURSDAY
EVENING INTO FRIDAY MORNING. COULD SEE AN INCH OR TWO OF
ACCUMULATION FROM THIS SYSTEM WITH THE 21.00Z GFS/ECMWF NOT TOO
FAR OFF FROM EACH OTHER.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 532 AM CST SUN DEC 21 2014

A WARM FRONT LIFTING NORTHWARD ACROSS THE REGION WILL CONTINUE TO
PRODUCE EXTENSIVE IFR/LIFR CONDITIONS THROUGH THE NEXT 24 HOURS.
MAY BE BRIEF BREAKS INTO MVFR AT KLSE BETWEEN 17Z-02Z. LOOKING
FOR SOME PERIODS OF DRIZZLE THROUGH THE DAY AS WELL AND THEN
LOOKING AT RAIN MOVING INTO THE AREA AFTER 06Z TONIGHT AS LOW
PRESSURE APPROACHES FROM THE NORTHERN PLAINS. OTHERWISE...
TIGHTENING PRESSURE GRADIENT IN ADVANCE OF THE APPROACHING LOW
WILL PRODUCE SOUTH WINDS AROUND 10KT AT KLSE AND IN THE 10-20KT
RANGE AT KRST.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ086-087-
     094-095.

IA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR IAZ008>011-
     018-019-029-030.

&&

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS




000
FXUS63 KARX 210930
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
330 AM CST SUN DEC 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CST SUN DEC 21 2014

THE MAIN FOCUS IS WITH THE DENSE FOG THIS MORNING ALONG WITH THE
DEVELOPING PRECIPITATION TODAY INTO TONIGHT.

DENSE FOG HAS FORMED ALONG AND NORTH OF A WARM FRONT THAT EXTENDS
EAST FROM THE SIOUX FALLS AREA ALONG THE IOWA/MINNESOTA BORDER
THEN RUNS SOUTHEAST INTO NORTHERN ILLINOIS. OBSERVATIONS IN
NORTHEAST IOWA ARE STILL SHOWING 1/4SM...SO PLAN TO LET THE
ADVISORY CONTINUE THROUGH THE MORNING OR UNTIL CONDITIONS IMPROVE.
THE 21.06Z HRRR/RAP SHOW THIS WARM FRONT ADVANCING NORTHWARD THIS
MORNING WITH THE BAND OF LOWEST VISIBILITIES ALSO LIFTING NORTH
AND DIMINISHING AS THE MORNING GOES ON. WILL HAVE TO KEEP AN EYE
ON OBS THROUGH THE MORNING FOR WHETHER THE ADVISORY CAN BE EXPIRED
EARLY.

GOING INTO THIS AFTERNOON...THERE HAS BEEN A FAIRLY CONSISTENT
MESSAGE OF PRECIPITATION DEVELOPING AS A 700MB TROUGH CATCHES UP
TO THE LOW LEVEL WARM AIR ADVECTION. THE HIGHEST CHANCES FOR THIS
PRECIPITATION CONTINUES TO BE ACROSS NORTHERN WISCONSIN WHERE THE
LIFT/MOISTURE WILL BE DEEPEST. THERMAL PROFILES LOOK COLD ENOUGH
TO SUPPORT ALL SNOW AT LEAST INITIALLY BEFORE THE WARM SECTOR
LIFTS NORTH TONIGHT. WITH ABOUT A TENTH OF AN INCH OF QPF AND SNOW
RATIOS AROUND 8:1 OR SO...AM EXPECTING A QUICK INCH OF SNOW IN
CLARK/TAYLOR COUNTIES THIS AFTERNOON WITH AREAS TO THE SOUTH
LIKELY SEEING MORE OF A DRIZZLE/RAIN SITUATION.

THE MAIN QUESTION WITH THIS PRECIPITATION IS WITH A DRY LAYER THAT
SHOWS UP ON 21.00Z NAM/GFS/RAP SOUNDINGS AROUND 800-700MB AND
WHETHER THAT COLUMN WILL BE SMALL ENOUGH FOR SEEDER-FEEDER TO
WORK. ALSO...SURFACE TEMPERATURES WILL BE ABOVE FREEZING...SO THIS
COMBINED WITH HOW DRY THE COLUMN IS LEADS TO SOME QUESTIONS WITH
PRECIPITATION TYPE. WITH FORCING RELATIVELY WEAK...EXPECT THAT THE
DRY LAYER WILL BE DEEP ENOUGH TO KEEP PRECIPITATION MORE AS
RAIN/DRIZZLE...PARTICULARLY WITH THE ABOVE FREEZING NEAR SURFACE
LAYER.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CST SUN DEC 21 2014

FAIRLY GOOD CONSENSUS AMONGST THE GUIDANCE WITH BRINGING THE MAIN
BAND OF PRECIPITATION THROUGH ON MONDAY INTO MONDAY EVENING AS THE
CLOSED MID LEVEL LOW APPROACHES AND A LEAD SHORTWAVE TROUGH LIFTS
NORTHWARD AHEAD OF IT. HAVE MAINLY GONE WITH RAIN AS THE
PRECIPITATION TYPE FOR MONDAY...BUT CONFIDENCE IS NOT VERY HIGH
WITH THIS AS FORECAST SOUNDINGS FROM THE 21.00Z NAM/GFS ONLY SHOW
THE WARM LAYER GETTING TO 1 TO 2C ABOVE FREEZING...IF THAT. 21.03Z
SREF PROBABILITIES SHOW MAINLY RAIN WITH THE EXCEPTION OF NORTHERN
WISCONSIN. IF IT IS NOT ALL RAIN...COULD BE SOME SLEET OR SNOW
THAT MIXES IN THERE AS WELL.

AFTER THE INITIAL BAND MOVES THROUGH BY MONDAY EVENING...THE
NAM/GFS SHOW THE DRY SLOW MOVING IN WHILE THE ECMWF SHOWS A
HEAVIER BAND OF RAIN/SNOW DEVELOPING NORTH OF A SURFACE LOW
TRACKING TO THE NORTH ALONG THE MISSISSIPPI. THE ECMWF THEN
DEVELOPS A DEEPER SURFACE LOW BY TUESDAY AFTERNOON COMPARED TO THE
NAM/GFS. SHOULD THE ECMWF SOLUTION BE THE TREND...WILL HAVE TO
PUSH PRECIPITATION CHANCES/AMOUNTS UP MORE THAN WHAT THEY
CURRENTLY ARE AT.

THE NEXT FEATURE OF NOTE IS WITH A PHASING MID LEVEL TROUGH THAT
LOOKS LIKE IT WILL BRING A BAND OF LIGHT SNOW IN ON THURSDAY
EVENING INTO FRIDAY MORNING. COULD SEE AN INCH OR TWO OF
ACCUMULATION FROM THIS SYSTEM WITH THE 21.00Z GFS/ECMWF NOT TOO
FAR OFF FROM EACH OTHER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ086-087-
     094-095.

IA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR IAZ008>011-
     018-019-029-030.

&&

$$

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





000
FXUS63 KARX 210930
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
330 AM CST SUN DEC 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CST SUN DEC 21 2014

THE MAIN FOCUS IS WITH THE DENSE FOG THIS MORNING ALONG WITH THE
DEVELOPING PRECIPITATION TODAY INTO TONIGHT.

DENSE FOG HAS FORMED ALONG AND NORTH OF A WARM FRONT THAT EXTENDS
EAST FROM THE SIOUX FALLS AREA ALONG THE IOWA/MINNESOTA BORDER
THEN RUNS SOUTHEAST INTO NORTHERN ILLINOIS. OBSERVATIONS IN
NORTHEAST IOWA ARE STILL SHOWING 1/4SM...SO PLAN TO LET THE
ADVISORY CONTINUE THROUGH THE MORNING OR UNTIL CONDITIONS IMPROVE.
THE 21.06Z HRRR/RAP SHOW THIS WARM FRONT ADVANCING NORTHWARD THIS
MORNING WITH THE BAND OF LOWEST VISIBILITIES ALSO LIFTING NORTH
AND DIMINISHING AS THE MORNING GOES ON. WILL HAVE TO KEEP AN EYE
ON OBS THROUGH THE MORNING FOR WHETHER THE ADVISORY CAN BE EXPIRED
EARLY.

GOING INTO THIS AFTERNOON...THERE HAS BEEN A FAIRLY CONSISTENT
MESSAGE OF PRECIPITATION DEVELOPING AS A 700MB TROUGH CATCHES UP
TO THE LOW LEVEL WARM AIR ADVECTION. THE HIGHEST CHANCES FOR THIS
PRECIPITATION CONTINUES TO BE ACROSS NORTHERN WISCONSIN WHERE THE
LIFT/MOISTURE WILL BE DEEPEST. THERMAL PROFILES LOOK COLD ENOUGH
TO SUPPORT ALL SNOW AT LEAST INITIALLY BEFORE THE WARM SECTOR
LIFTS NORTH TONIGHT. WITH ABOUT A TENTH OF AN INCH OF QPF AND SNOW
RATIOS AROUND 8:1 OR SO...AM EXPECTING A QUICK INCH OF SNOW IN
CLARK/TAYLOR COUNTIES THIS AFTERNOON WITH AREAS TO THE SOUTH
LIKELY SEEING MORE OF A DRIZZLE/RAIN SITUATION.

THE MAIN QUESTION WITH THIS PRECIPITATION IS WITH A DRY LAYER THAT
SHOWS UP ON 21.00Z NAM/GFS/RAP SOUNDINGS AROUND 800-700MB AND
WHETHER THAT COLUMN WILL BE SMALL ENOUGH FOR SEEDER-FEEDER TO
WORK. ALSO...SURFACE TEMPERATURES WILL BE ABOVE FREEZING...SO THIS
COMBINED WITH HOW DRY THE COLUMN IS LEADS TO SOME QUESTIONS WITH
PRECIPITATION TYPE. WITH FORCING RELATIVELY WEAK...EXPECT THAT THE
DRY LAYER WILL BE DEEP ENOUGH TO KEEP PRECIPITATION MORE AS
RAIN/DRIZZLE...PARTICULARLY WITH THE ABOVE FREEZING NEAR SURFACE
LAYER.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 330 AM CST SUN DEC 21 2014

FAIRLY GOOD CONSENSUS AMONGST THE GUIDANCE WITH BRINGING THE MAIN
BAND OF PRECIPITATION THROUGH ON MONDAY INTO MONDAY EVENING AS THE
CLOSED MID LEVEL LOW APPROACHES AND A LEAD SHORTWAVE TROUGH LIFTS
NORTHWARD AHEAD OF IT. HAVE MAINLY GONE WITH RAIN AS THE
PRECIPITATION TYPE FOR MONDAY...BUT CONFIDENCE IS NOT VERY HIGH
WITH THIS AS FORECAST SOUNDINGS FROM THE 21.00Z NAM/GFS ONLY SHOW
THE WARM LAYER GETTING TO 1 TO 2C ABOVE FREEZING...IF THAT. 21.03Z
SREF PROBABILITIES SHOW MAINLY RAIN WITH THE EXCEPTION OF NORTHERN
WISCONSIN. IF IT IS NOT ALL RAIN...COULD BE SOME SLEET OR SNOW
THAT MIXES IN THERE AS WELL.

AFTER THE INITIAL BAND MOVES THROUGH BY MONDAY EVENING...THE
NAM/GFS SHOW THE DRY SLOW MOVING IN WHILE THE ECMWF SHOWS A
HEAVIER BAND OF RAIN/SNOW DEVELOPING NORTH OF A SURFACE LOW
TRACKING TO THE NORTH ALONG THE MISSISSIPPI. THE ECMWF THEN
DEVELOPS A DEEPER SURFACE LOW BY TUESDAY AFTERNOON COMPARED TO THE
NAM/GFS. SHOULD THE ECMWF SOLUTION BE THE TREND...WILL HAVE TO
PUSH PRECIPITATION CHANCES/AMOUNTS UP MORE THAN WHAT THEY
CURRENTLY ARE AT.

THE NEXT FEATURE OF NOTE IS WITH A PHASING MID LEVEL TROUGH THAT
LOOKS LIKE IT WILL BRING A BAND OF LIGHT SNOW IN ON THURSDAY
EVENING INTO FRIDAY MORNING. COULD SEE AN INCH OR TWO OF
ACCUMULATION FROM THIS SYSTEM WITH THE 21.00Z GFS/ECMWF NOT TOO
FAR OFF FROM EACH OTHER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ086-087-
     094-095.

IA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR IAZ008>011-
     018-019-029-030.

&&

$$

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




000
FXUS63 KARX 210545
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1145 PM CST SAT DEC 20 2014

.UPDATE...
ISSUED AT 1145 PM CST SAT DEC 20 2014

VISIBILITIES HAVE FALLEN TO LESS THAN 1/4 MILE AT OELWEIN AND
CHARLES CITY. THE 21.00Z HIRES-ARW SEEMS TO HAVE THE BEST HANDLE
ON THE FOG...SUGGESTING IT PERSISTS OVER NORTHEAST IOWA OVERNIGHT
WHILE EXPANDING INTO SOUTHEAST MN. EVENTUALLY DURING THE DAY
SUNDAY IT DIMINISHES AND LIFTS NORTH. SINCE THERE IS A PERSISTENT
FEED OF MOISTURE INTO THE REGION...REPRESENTED BY MID 30S
DEWPOINTS IN SOUTHERN IOWA TRYING TO PUSH INTO TEMPERATURES IN THE
29-32 RANGE...A PERSISTENT DENSE FOG SCENARIO SEEMS LIKELY.
THEREFORE...HAVE ISSUED AN ADVISORY. HAVE KEPT OUT
WABASHA...WINONA AND HOUSTON COUNTIES FOR NOW GIVEN THE LOW LEVEL
FLOW BEING SOUTHEASTERLY. HOWEVER...THESE COUNTIES MAY YET NEED AN
ADVISORY LATER TONIGHT. WOULD NOT COUNT OUT THE HIGHER TERRAIN OF
SOUTHWEST WI NEEDING AN ADVISORY AS WELL.

ALSO...WITH AIR AND ROAD TEMPS AT OR BELOW FREEZING...THERE COULD
BE SOME ICY SPOTS.

&&

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR MNZ086-087-094-095.

IA...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR IAZ008>011-018-019-
     029-030.

&&

$$

UPDATE...AJ
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ




000
FXUS63 KARX 210545
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1145 PM CST SAT DEC 20 2014

.UPDATE...
ISSUED AT 1145 PM CST SAT DEC 20 2014

VISIBILITIES HAVE FALLEN TO LESS THAN 1/4 MILE AT OELWEIN AND
CHARLES CITY. THE 21.00Z HIRES-ARW SEEMS TO HAVE THE BEST HANDLE
ON THE FOG...SUGGESTING IT PERSISTS OVER NORTHEAST IOWA OVERNIGHT
WHILE EXPANDING INTO SOUTHEAST MN. EVENTUALLY DURING THE DAY
SUNDAY IT DIMINISHES AND LIFTS NORTH. SINCE THERE IS A PERSISTENT
FEED OF MOISTURE INTO THE REGION...REPRESENTED BY MID 30S
DEWPOINTS IN SOUTHERN IOWA TRYING TO PUSH INTO TEMPERATURES IN THE
29-32 RANGE...A PERSISTENT DENSE FOG SCENARIO SEEMS LIKELY.
THEREFORE...HAVE ISSUED AN ADVISORY. HAVE KEPT OUT
WABASHA...WINONA AND HOUSTON COUNTIES FOR NOW GIVEN THE LOW LEVEL
FLOW BEING SOUTHEASTERLY. HOWEVER...THESE COUNTIES MAY YET NEED AN
ADVISORY LATER TONIGHT. WOULD NOT COUNT OUT THE HIGHER TERRAIN OF
SOUTHWEST WI NEEDING AN ADVISORY AS WELL.

ALSO...WITH AIR AND ROAD TEMPS AT OR BELOW FREEZING...THERE COULD
BE SOME ICY SPOTS.

&&

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR MNZ086-087-094-095.

IA...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR IAZ008>011-018-019-
     029-030.

&&

$$

UPDATE...AJ
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ





000
FXUS63 KARX 210458
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1058 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ




000
FXUS63 KARX 210458
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1058 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ





000
FXUS63 KARX 210458
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1058 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ





000
FXUS63 KARX 210458
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1058 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT OVER SOUTHERN
IOWA AND ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF
SITES. THEREFORE...THE STRATUS WILL PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. RST STANDS TO
SEE THE WORST CONDITIONS BEING A HIGHER ELEVATION...AND LIFR TO
VLIFR CONDITIONS ARE POSSIBLE BY 12Z. ADDITIONALLY...WITH THE
APPROACH OF THE WARM FRONT...ANTICIPATING DZ/FZDZ TO FORM. THIS
TOO SHOULD BE MORE PREVALENT AT RST. ANY IMPROVEMENT ON SUNDAY
SHOULD BE VERY SLOW TO OCCUR...IF AT ALL...GIVEN THE PERSISTENT
MOISTURE FEED. IF THERE IS NOT ANY IMPROVEMENT ON SUNDAY...WILL
HAVE TO WATCH VISIBILITIES SUNDAY NIGHT CLOSELY AT RST. RIGHT NOW
BROUGHT RST BACK DOWN TO LIFR. CEILING SHOULD ALSO LOWER AT LSE TO
IFR WITH CONTINUED INFLUX OF MOISTURE AND NIGHTTIME COOLING.

REGARDING THE WINDS...EXPECT THEM TO INCREASE THROUGH THE NEXT 24
HOURS AS THE GRADIENT TIGHTENS. 15-20 KT WINDS SHOULD BE COMMON AT
RST IN THE AFTERNOON AND EVENING...AND AROUND 10 KT AT LSE.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ




000
FXUS63 KARX 202345
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
545 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 545 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT NEAR I-70 AND
ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF SITES.
THEREFORE...THE STRATUS IS LIKELY TO PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. NIGHTTIME
COOLING WILL ALSO AID IN LOWERING CEILINGS AND VISIBILITIES. RST
STANDS TO SEE THE WORST CONDITIONS BEING A HIGHER TERRAIN
SITE...AND LIFR TO VLIFR CONDITIONS ARE POSSIBLE BY 12Z.
ADDITIONALLY...WITH THE APPROACH OF THE WARM FRONT...ANTICIPATING
DZ/FZDZ TO FORM. THIS TOO SHOULD BE MORE PREVALENT AT RST. ANY
IMPROVEMENT ON SUNDAY SHOULD BE VERY SLOW TO OCCUR...IF AT
ALL...GIVEN THE PERSISTENT MOISTURE FEED. IF THERE IS NOT ANY
IMPROVEMENT ON SUNDAY...WILL HAVE TO WATCH VISIBILITIES SUNDAY
NIGHT CLOSELY.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ





000
FXUS63 KARX 202345
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
545 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 545 PM CST SAT DEC 20 2014

STRATUS REMAINS AT BOTH TAF SITES WITH MVFR CEILINGS AT LSE AND
IFR CEILINGS AT RST. SOUTHERLY FLOW IS EXPECTED TO CONTINUE
THROUGH THE NEXT 24 HOURS...ALLOWING A WARM FRONT NEAR I-70 AND
ITS ASSOCIATED MOISTURE TO LIFT NORTH INTO THE TAF SITES.
THEREFORE...THE STRATUS IS LIKELY TO PERSIST WITH THE INCOMING
MOISTURE ALLOWING CEILINGS AND VISIBILITIES TO FALL. NIGHTTIME
COOLING WILL ALSO AID IN LOWERING CEILINGS AND VISIBILITIES. RST
STANDS TO SEE THE WORST CONDITIONS BEING A HIGHER TERRAIN
SITE...AND LIFR TO VLIFR CONDITIONS ARE POSSIBLE BY 12Z.
ADDITIONALLY...WITH THE APPROACH OF THE WARM FRONT...ANTICIPATING
DZ/FZDZ TO FORM. THIS TOO SHOULD BE MORE PREVALENT AT RST. ANY
IMPROVEMENT ON SUNDAY SHOULD BE VERY SLOW TO OCCUR...IF AT
ALL...GIVEN THE PERSISTENT MOISTURE FEED. IF THERE IS NOT ANY
IMPROVEMENT ON SUNDAY...WILL HAVE TO WATCH VISIBILITIES SUNDAY
NIGHT CLOSELY.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ




000
FXUS63 KARX 202045
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
245 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1138 AM CST SAT DEC 20 2014

LOW STRATUS/FOG/DRIZZLE WILL CONTINUE TO BE PROBLEMATIC THROUGH THE
PERIOD...ALTHOUGH GUIDANCE NOT RESOLVING LOW-LEVEL MOISTURE WELL. AS
A RESULT...OVERALL FORECAST CONFIDENCE IS LOW. 20.18Z TAFS WILL
CLOSELY FOLLOW RECENT OBSERVATIONAL TRENDS WITH IFR CEILINGS/ MVFR
VISIBILITIES AT KRST AND MVFR CEILINGS/VFR VISIBILITIES AT KLSE.
LIFT INCREASES OVERNIGHT IN THE SHALLOW NEAR SURFACE SATURATED
LAYER...SO WILL DROP KRST CEILING BACK DOWN TO 200 FT AGL WITH 1/2SM
IN FZFG/FZDZ BY 21.11Z. WILL ALSO DROP KLSE A CATEGORY BY 12.10Z...
BUT KEEP OUT FZFG/FZDZ FOR NOW. FOR BOTH SITES...WILL NEED TO
CLOSELY WATCH OBSERVATIONAL TRENDS AS AMENDMENTS ARE LIKELY THROUGH
THE PERIOD.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....ROGERS





000
FXUS63 KARX 202045
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
245 PM CST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THRU SUNDAY NIGHT)
ISSUED AT 245 PM CST SAT DEC 20 2014

THE MAIN FCST CONCERNS THIS PERIOD...PRECIP TYPES/CHANCES THRU THE
PERIOD...TEMPERATURES.

DATA ANALYSIS AT 18Z HAD BROAD HIGH PRESSURE RIDGING FROM QUEBEC TO
AR WITH LOW PRESSURE DEVELOPING IN THE LEE OF THE US/CAN ROCKIES.
VIS IMAGERY/SFC OBS SHOWING A BROAD LOW STRATUS SHIELD  ACROSS
THE UPPER MIDWEST AND NEARBY AREAS EARLY THIS AFTERNOON. PRESSURE
GRADIENT SLOWLY INCREASING ACROSS MN/IA/WI AS THE HIGH MOVES EAST
AND PRESSURES FALL IN THE NORTHERN PLAINS. SOUTHERLY FLOW SLOWLY
BRINGING WARMER AIR NORTHWARD...WITH TEMPS UNDER THE LOW STRATUS
DECK SLOWLY CREEPING TO NEAR/ABOVE 32F ACROSS MUCH OF IA/SOUTHERN
MN/WESTERN WI.

20.12Z MODELS INITIALIZED WELL AND SOLUTIONS QUITE SIMILAR FOR
TONIGHT THRU SUN NIGHT. STRONG ENERGY WITH THE 180-190KT 250-300MB
PAC JET COMES ONSHORE NEAR THE US/CAN BORDER LATE THIS AFTERNOON/
TONIGHT...KICKING A SHORTWAVE NEAR THE MT/ND BORDER EAST/NORTHEAST
TONIGHT/EARLY SUN. THIS PAC ENERGY THEN DEVELOPS STRONGER
TROUGHING IN THE CENTRAL/NORTHERN PLAINS SUN/SUN NIGHT AS THE
STRONG JET MAX DIGS THRU CENTRAL/NORTHERN ROCKIES. SHORT-TERM
FCST CONFIDENCE REMAINS GOOD THIS CYCLE.

FOR THE SHORT TERM...SOUTH TO SOUTHWEST SFC-700MB FLOW OVER THE AREA
INCREASES THRU THE PERIOD AS HGTS FALL AND SFC LOW PRESSURE DEEPENS
IN THE NORTHERN PLAINS. SFC-850MB TEMPS WARM IN THIS PERSISTENT
SOUTH/SOUTHWEST LOW LEVEL WARM ADVECTION FLOW. THRU LATE TONIGHT/
SUN MORNING THE SFC-925MB LAYER IS PROGGED TO WARM ABOVE 0C ACROSS
ALL BUT THE NORTH END OF THE FCST AREA. THIS ABOVE FREEZING LAYER
DEEPENS TO 900-850MB THRU SUN AFTERNOON/NIGHT OVER THE CENTRAL/
SOUTH PARTS OF THE FCST AREA. THIS LAYER DOES NOT APPEAR TO GET
OVERLY WARM...WITH MAX TEMPS IN THE LAYER BETWEEN +2C AND +4C.
THIS LAYER NOT A TRUE WARM LAYER ALOFT EITHER AS THERE IS NO
FREEZING LAYER BETWEEN IT AND THE SFC. THUS TOP-DOWN APPROACH
WOULD LIMIT PRECIP TYPES BY THE DEPTH OF THE WARM LAYER MELTING
PARTICLES AS THEY FALL THRU IT AND THE GROUND/SFC TEMPS. THIS
LIMITS PRECIP TYPES BY LATER SUN/SUN NIGHT TO -RA/-SN OR -FZRA IF
THE GROUND SFCS ARE COLD ENOUGH. ROAD TEMP SENSOR DATA THAT IS
AVAILABLE SHOWING READINGS IN THE UPPER 20S TO MID 30S THIS
AFTERNOON...AND ONLY LIKELY TO GO UP THE NEXT 36-48HRS. WITH A BIT
STRONGER SURGE OF SFC-850MB WARM ADVECTION TONIGHT AND INCREASING
WINDS FOR BOUNDARY LAYER MIXING...LOWS TONIGHT MAY WELL BE IN THE
EVENING WITH STEADY/SLOWLY RISING TEMPS OVERNIGHT. TOP OF MOISTURE
COLUMN ONLY AROUND 850MB TONIGHT WITH CLOUD-TOP TEMPS WARMER THAN
-5C. WILL CONTINUE THE PATCHY/AREAS -FZDZ LATER TONIGHT
TRANSITIONING TO -RA OR A -RA/-SN MIX FOR SUN/SUN NIGHT AS THE
DEPTH OF MOISTURE/WARM LAYER AND LIFT INCREASE. WILL CONTINUE
SOME -FZRA MENTION SUN MORNING WHEN ROAD SFCS MAY STILL BE COLD
ENOUGH TO FREEZE THE DROPS.

AGAIN TRENDED TOWARD WARMER OF GUIDANCE LOWS FOR TONIGHT/SUN NIGHT
WITH THICK LOW CLOUDS AND INCREASING SOUTH GRADIENT WINDS. USED A
BLEND OF THE GUIDANCE HIGHS FOR SUN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 245 PM CST SAT DEC 20 2014

FCST CONCERNS FOR MON THRU TUE NIGHT...PRECIP CHANCES/TYPES AND
TEMPERATURES THRU THE PERIOD.

20.12Z MODELS IN GENERAL AGREEMENT FOR A DEEPENING TROUGH OVER THE
CENTRAL CONUS MON THRU TUE NIGHT. HOWEVER MODELS DIFFER QUITE A BIT
ON THE DETAILS IN THIS TROUGH AND RESULTING LOW LEVEL FEATURES/FIELDS
BY LATER MON NIGHT AND FOR TUE/TUE NIGHT. OVERALL TREND IS MORE OF
THE ENERGY IN THE SOUTHERN/BOTTOM PORTION OF THE TROUGH BY TUE/TUE
NIGHT WITH LESSER RUN-TO-RUN CONSISTENCY IN THESE PERIODS. SUSPECT
THIS TREND WILL CONTINUE IN FUTURE RUNS WITH A WEAKER LOOK/SLOWING
OF THE UPSTREAM SYSTEM BEHIND IT OVER THE EASTERN PAC. FCST
CONFIDENCE IS AVERAGE TO GOOD MON/MON NIGHT THEN AVERAGE FOR TUE/TUE
NIGHT.

DEPTH OF MOISTURE AND STRENGTH/DEPTH OF FORCING/LIFT INCREASE FOR
MON AS THE MAIN BAND OF LOWER LEVEL THERMODYNAMIC FORCING AND A
ROUND OF 500-300MB PV ADVECTION WITH SOME OF THE LEAD SHORTWAVE
ENERGY IN THE TROUGH ROTATES ACROSS THE REGION. RAISED PRECIP
CHANCES MON INTO THE 70-90 PERCENT RANGE. MODEL SOUNDINGS/X-SECTIONS
SHOW THE SFC-900MB LAYER SHOULD BE WARM ENOUGH FOR THE BULK OF THIS
TO FALL AS RAIN ACROSS THE FCST AREA...POSSIBLY MIXED WITH SOME SNOW
ACROSS THE NORTH END OF THE FCST AREA WHERE THE FREEZING LEVEL MAY
BE MORE BETWEEN 950-925MB. WITH THE DEVELOPING SPLIT OF THE ENERGY
IN THE TROUGH THE NORTHERN SFC-700MB CIRCULATION REMAINS WEST/NORTH
OF THE FCST AREA THRU MON NIGHT. A WEAK SFC-700MB FRONT/TROUGH SOUTH
OF THIS LOW SLIDES ACROSS THE AREA MON NIGHT...WITH SLOW COOLING OF
THE LOWER PORTIONS OF THE COLUMN. A 700-500MB DRY WEDGE SPREADS
NORTHEAST ACROSS THE FCST AREA AS WELL MON NIGHT...SO MAY LOSE ICE
IN THE CLOUDS. PRECIP TO TAPER OFF MON NIGHT AND GRADUALLY MIX
WITH/CHANGE TO -SN. WITH LOSS OF ICE WOULD TRANSITION TO -DZ. CARRIED
HIGHEST CHANCES OVER THE EAST HALF OF THE FCST AREA MON EVENING.

COLUMN CONTINUES TO COOL TUE/TUE NIGHT AS THE NORTHERN SFC-700MB LOW
WEAKENS AND DRIFTS ACROSS THE REGION. ENERGY TRANSFERRING TO THE
SOUTHERN PORTION OF THE TROUGH DEVELOPS ANOTHER LOW IN THE SOUTHERN
MS VALLEY TUE AND LIFTS IT NORTH/NORTHEAST TUE NIGHT. PLENTY OF
TIMING/DETAIL/TRACK DIFFERENCES WITH THIS LOW AND RESULTING
FORCING/LIFT/MOISTURE FIELDS FOR LATER TUE/TUE NIGHT. LEFT -RA/-SN
CHANCES TUE IN THE 30-50 PERCENT RANGE AND SNOW CHANCES TUE NIGHT IN
THE 20-30 PERCENT RANGE...PENDING WHICH MODEL OUTCOME MAY BE MORE
CORRECT. USED A BLEND OF THE GUIDANCE HIGHS FOR MON/TUE AND TRENDED
TOWARD WARMER OF GUIDANCE LOWS FOR MON/TUE NIGHT.

FOR WEDNESDAY THRU SATURDAY...DAYS 4 TO 7...

FCST CONCERNS THIS PERIOD...SNOW CHANCES WED AND FRI...
TEMPERATURES THRU THE PERIOD.

20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR WED THRU
SAT...BUT THIS LEAVES SOME OF THEM WITH RATHER POOR RUN-TO-RUN
CONSISTENCY. MODELS IN AGREEMENT TO SWEEP THE FULL LATITUDE
TROUGH/LOW OVER THE CENTRAL CONUS QUICKLY INTO THE EASTERN CONUS FOR
THU...WITH SHORTWAVE RIDGING BUILDING OVER THE UPPER MIDWEST FOR
THU. NEXT ENERGY THRU THE FLOW HEADS TOWARD THE REGION FROM THE
CENTRAL ROCKIES FRIDAY...THEN COLD TROUGHING/NORTHWEST FLOW OVER THE
REGION SAT. FCST CONFIDENCE AVERAGE FOR WED THEN AVERAGE TO BELOW
FOR THU-SAT UNTIL MODELS SETTLE ON A MORE RUN-TO-RUN CONSISTENT
SOLUTION.

MORE ENERGY IN THE SOUTHERN PORTION OF THE TROUGH WED DRAGS ANY MID
LEVEL LOW AND THE DEEPER FORCING/LIFT/MOISTURE EVEN FURTHER SOUTH/
EAST OF THE FCST AREA FOR WED. BULK OF SNOW ON WED NOW LOOKING TO BE
EAST OF THE FCST AREA AS THE LOW LIFTING OUT OF THE LOWER MS VALLEY
WOULD DEEPEN OVER MI OR THE OH VALLEY...LEAVING WED TO MAINLY BE A
BREEZY DAY WITH SOME -SN OR FLURRIES. NOW LOOKING LIKE ANY PRE-
CHRISTMAS SNOW FOR THE AREA LATER TUE INTO WED WILL BE AN INCH OR
LESS. TROUGH/MID LEVEL LOW BEING PULLED EAST MORE QUICKLY SPREADS
DRYING NORTHWEST FLOW ALOFT ACROSS THE AREA FOR WED NIGHT. WEAK
RIDGE OF SFC HIGH PRESSURE TO SLIDE INTO/ACROSS THE AREA LATER WED
NIGHT/THU. SYSTEM COMING FROM THE CENTRAL ROCKIES FRI WOULD SPREAD A
ROUND OF LIFT ACROSS THE AREA...BUT IN THE WAKE OF THE STRONGER
SYSTEM LIFTING THRU THE EASTERN CONUS WED/WED NIGHT APPEARS THIS ONE
WILL HAVE MINIMAL MOISTURE TO WORK WITH. 35-45 PERCENT -SN CHANCES
CENTERED ON FRI GOOD FOR NOW. CAN HIGH PRESSURE WOULD BUILD IN FOR
SAT UNDER DRIER/COLDER NORTHWEST FLOW ALOFT. MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS FOR WED THRU SAT APPEAR GOOD AT THIS TIME.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1138 AM CST SAT DEC 20 2014

LOW STRATUS/FOG/DRIZZLE WILL CONTINUE TO BE PROBLEMATIC THROUGH THE
PERIOD...ALTHOUGH GUIDANCE NOT RESOLVING LOW-LEVEL MOISTURE WELL. AS
A RESULT...OVERALL FORECAST CONFIDENCE IS LOW. 20.18Z TAFS WILL
CLOSELY FOLLOW RECENT OBSERVATIONAL TRENDS WITH IFR CEILINGS/ MVFR
VISIBILITIES AT KRST AND MVFR CEILINGS/VFR VISIBILITIES AT KLSE.
LIFT INCREASES OVERNIGHT IN THE SHALLOW NEAR SURFACE SATURATED
LAYER...SO WILL DROP KRST CEILING BACK DOWN TO 200 FT AGL WITH 1/2SM
IN FZFG/FZDZ BY 21.11Z. WILL ALSO DROP KLSE A CATEGORY BY 12.10Z...
BUT KEEP OUT FZFG/FZDZ FOR NOW. FOR BOTH SITES...WILL NEED TO
CLOSELY WATCH OBSERVATIONAL TRENDS AS AMENDMENTS ARE LIKELY THROUGH
THE PERIOD.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....ROGERS




000
FXUS63 KARX 201738
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1138 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CST SAT DEC 20 2014

THE MAIN FOCUS TODAY INTO TONIGHT CONTINUES TO BE ON THE
PROBABILITIES OF SEEING SOME FREEZING DRIZZLE AND FLURRIES.

CURRENTLY IN WEAK SOUTHERLY FLOW IN THE LOW LEVELS WITH A RIDGE
OVER THE CENTRAL GREAT LAKES AND LOW PRESSURE OVER THE EASTERN
ROCKIES. A CLOSED MID LEVEL LOW IS DRIFTING EAST ACROSS SOUTHERN
MANITOBA/ONTARIO WHILE A SHORT WAVE TROUGH DIVES SOUTH OF IT INTO
IOWA. SOME WEAK LOW LEVEL WARM AIR ADVECTION HAS LEAD TO SOME
LOWER STRATUS TO FORM ALONG AND EAST OF THE INTERSTATE 35
CORRIDOR. THERE IS JUST ENOUGH LIFT THERE TO PRODUCE SOME DRIZZLE AND
WITH TEMPERATURES BELOW FREEZING THERE HAS BEEN SOME SPOTS THAT
HAVE REPORTED SOME LIGHT GLAZING ON ROADS AND OTHER EXTERNAL
SURFACES. THIS WAA APPEARS TO WEAKEN FOR A PERIOD TODAY BEFORE
STRENGTHENING AGAIN TONIGHT ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN. COULD SEE SOME MORE OF THE SAME WITH THE COLUMN NOT
HAVING ANY ICE PRESENT AND SURFACE TEMPERATURES BELOW FREEZING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 339 AM CST SAT DEC 20 2014

QUITE THE MESSY PATTERN THROUGH THE WEEK WITH THURSDAY LOOKING THE
MOST LIKELY TO BE THE ONLY DRY ONE OF THE BUNCH. PRECIPITATION
SHOULD BECOME A BIT MORE WIDESPREAD...THOUGH STILL LIGHT...ON
SUNDAY AS A 700MB TROUGH INTERACTS WITH THE LOW LEVEL WARM AIR
ADVECTION. LIFT/MOISTURE LOOKS DEEP ENOUGH TO INTRODUCE SOME ICE
THOUGH IT ALSO BRINGS AN ABOVE FREEZING WARM LAYER IN AROUND 850MB
AS WELL. THEREFORE...PRECIPITATION TYPE IS A MESS FOR SUNDAY WITH
PERHAPS SOME FREEZING DRIZZLE TO START IN THE MORNING AS THE DRY
AIR BETWEEN 900-700MB IS TOO DEEP FOR SEEDER FEEDER TO WORK. AS
THE COLUMN STARTS TO SATURATE UNDER THE DEEPER LIFT IN THE
AFTERNOON...THE WARM LAYER MOVES IN WITH THE PRECIPITATION TYPE
LIKELY BEING SNOW OR SLEET INITIALLY. 20.00Z NAM/GFS SOUNDINGS
THEN INDICATE THAT AS THE PRECIPITATION FALLS THAT THE WARM LAYER
SHOULD COOL AGAIN WITH THE PRECIP TYPE CHANGING BACK TO SNOW. AS
THE WAVE THEN SHIFTS TO THE EAST SUNDAY NIGHT...IT APPEARS AS
THOUGH ICE IS LOST AND THAT THE PRECIPITATION TYPE THEN GOES BACK
TO BEING DRIZZLE.

WARMER AIR SHOULD THEN MOVE IN ON MONDAY AS A MORE POTENT TROUGH
DEVELOPS OVER THE DAKOTAS. THE 20.00Z NAM/ECMWF TRENDS APPEAR TO
BE PREFERRED OVER THE 20.00Z GFS WHICH IS MUCH FASTER WITH THE
CLOSED LOW. THE NAM/ECMWF SOLUTION BRINGS A BAND OF RAIN THROUGH
AND LIFTS IT TO THE NORTHEAST BY MONDAY EVENING WITH THE DRY SLOT
OF THE SYSTEM MOVING IN. THE GFS HAS THE SURFACE LOW MUCH FURTHER
SOUTH AS WELL AND WOULD KEEP PRECIP AROUND MUCH LONGER.
OVERALL...CONFIDENCE IN HOW THIS SYSTEM WILL PLAY OUT IS PRETTY
LOW AT THIS POINT.

COLDER AIR WILL MOVE IN BY MID WEEK WITH ANY PRECIPITATION
FALLING THROUGH THE REST OF THE WEEK EXPECTED TO BE SNOW. A SYSTEM
OF INTEREST IS WITH WHAT THE 20.00Z ECMWF IS SHOWING FOR THURSDAY
NIGHT THROUGH FRIDAY NIGHT. WHILE THE 20.00Z GFS ONLY HAS A WEAK
INVERTED TROUGH MOVING THROUGH THE ECMWF SHOWS A POTENT STORM
SYSTEM TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY REGION
WITH A DEEPENING SURFACE LOW PROPAGATING FROM THE SOUTHERN PLAINS
THROUGH NORTHERN ILLINOIS ON TOWARD CENTRAL LAKE MICHIGAN. MODEL
CONSISTENCY HAS BEEN ALL OVER THE PLACE FOR THIS TIME FRAME...SO
WILL HAVE TO WAIT AND SEE WHAT LATER RUNS COME UP WITH.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1138 AM CST SAT DEC 20 2014

LOW STRATUS/FOG/DRIZZLE WILL CONTINUE TO BE PROBLEMATIC THROUGH
THE PERIOD...ALTHOUGH GUIDANCE NOT RESOLVING LOW-LEVEL MOISTURE
WELL. AS A RESULT...OVERALL FORECAST CONFIDENCE IS LOW. 20.18Z TAFS
WILL CLOSELY FOLLOW RECENT OBSERVATIONAL TRENDS WITH IFR CEILINGS/
MVFR VISIBILITIES AT KRST AND MVFR CEILINGS/VFR VISIBILITIES AT
KLSE. LIFT INCREASES OVERNIGHT IN THE SHALLOW NEAR SURFACE SATURATED
LAYER...SO WILL DROP KRST CEILING BACK DOWN TO 200 FT AGL WITH
1/2SM IN FZGF/FZDZ BY 21.11Z. WILL ALSO DROP KLSE A CATEGORY BY
12.10Z...BUT KEEP OUT FZFG/FZDZ FOR NOW. FOR BOTH SITES...WILL
NEED TO CLOSELY WATCH OBSERVATIONAL TRENDS AS AMENDMENTS ARE
LIKELY THROUGH THE PERIOD.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ROGERS





000
FXUS63 KARX 201738
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1138 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CST SAT DEC 20 2014

THE MAIN FOCUS TODAY INTO TONIGHT CONTINUES TO BE ON THE
PROBABILITIES OF SEEING SOME FREEZING DRIZZLE AND FLURRIES.

CURRENTLY IN WEAK SOUTHERLY FLOW IN THE LOW LEVELS WITH A RIDGE
OVER THE CENTRAL GREAT LAKES AND LOW PRESSURE OVER THE EASTERN
ROCKIES. A CLOSED MID LEVEL LOW IS DRIFTING EAST ACROSS SOUTHERN
MANITOBA/ONTARIO WHILE A SHORT WAVE TROUGH DIVES SOUTH OF IT INTO
IOWA. SOME WEAK LOW LEVEL WARM AIR ADVECTION HAS LEAD TO SOME
LOWER STRATUS TO FORM ALONG AND EAST OF THE INTERSTATE 35
CORRIDOR. THERE IS JUST ENOUGH LIFT THERE TO PRODUCE SOME DRIZZLE AND
WITH TEMPERATURES BELOW FREEZING THERE HAS BEEN SOME SPOTS THAT
HAVE REPORTED SOME LIGHT GLAZING ON ROADS AND OTHER EXTERNAL
SURFACES. THIS WAA APPEARS TO WEAKEN FOR A PERIOD TODAY BEFORE
STRENGTHENING AGAIN TONIGHT ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN. COULD SEE SOME MORE OF THE SAME WITH THE COLUMN NOT
HAVING ANY ICE PRESENT AND SURFACE TEMPERATURES BELOW FREEZING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 339 AM CST SAT DEC 20 2014

QUITE THE MESSY PATTERN THROUGH THE WEEK WITH THURSDAY LOOKING THE
MOST LIKELY TO BE THE ONLY DRY ONE OF THE BUNCH. PRECIPITATION
SHOULD BECOME A BIT MORE WIDESPREAD...THOUGH STILL LIGHT...ON
SUNDAY AS A 700MB TROUGH INTERACTS WITH THE LOW LEVEL WARM AIR
ADVECTION. LIFT/MOISTURE LOOKS DEEP ENOUGH TO INTRODUCE SOME ICE
THOUGH IT ALSO BRINGS AN ABOVE FREEZING WARM LAYER IN AROUND 850MB
AS WELL. THEREFORE...PRECIPITATION TYPE IS A MESS FOR SUNDAY WITH
PERHAPS SOME FREEZING DRIZZLE TO START IN THE MORNING AS THE DRY
AIR BETWEEN 900-700MB IS TOO DEEP FOR SEEDER FEEDER TO WORK. AS
THE COLUMN STARTS TO SATURATE UNDER THE DEEPER LIFT IN THE
AFTERNOON...THE WARM LAYER MOVES IN WITH THE PRECIPITATION TYPE
LIKELY BEING SNOW OR SLEET INITIALLY. 20.00Z NAM/GFS SOUNDINGS
THEN INDICATE THAT AS THE PRECIPITATION FALLS THAT THE WARM LAYER
SHOULD COOL AGAIN WITH THE PRECIP TYPE CHANGING BACK TO SNOW. AS
THE WAVE THEN SHIFTS TO THE EAST SUNDAY NIGHT...IT APPEARS AS
THOUGH ICE IS LOST AND THAT THE PRECIPITATION TYPE THEN GOES BACK
TO BEING DRIZZLE.

WARMER AIR SHOULD THEN MOVE IN ON MONDAY AS A MORE POTENT TROUGH
DEVELOPS OVER THE DAKOTAS. THE 20.00Z NAM/ECMWF TRENDS APPEAR TO
BE PREFERRED OVER THE 20.00Z GFS WHICH IS MUCH FASTER WITH THE
CLOSED LOW. THE NAM/ECMWF SOLUTION BRINGS A BAND OF RAIN THROUGH
AND LIFTS IT TO THE NORTHEAST BY MONDAY EVENING WITH THE DRY SLOT
OF THE SYSTEM MOVING IN. THE GFS HAS THE SURFACE LOW MUCH FURTHER
SOUTH AS WELL AND WOULD KEEP PRECIP AROUND MUCH LONGER.
OVERALL...CONFIDENCE IN HOW THIS SYSTEM WILL PLAY OUT IS PRETTY
LOW AT THIS POINT.

COLDER AIR WILL MOVE IN BY MID WEEK WITH ANY PRECIPITATION
FALLING THROUGH THE REST OF THE WEEK EXPECTED TO BE SNOW. A SYSTEM
OF INTEREST IS WITH WHAT THE 20.00Z ECMWF IS SHOWING FOR THURSDAY
NIGHT THROUGH FRIDAY NIGHT. WHILE THE 20.00Z GFS ONLY HAS A WEAK
INVERTED TROUGH MOVING THROUGH THE ECMWF SHOWS A POTENT STORM
SYSTEM TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY REGION
WITH A DEEPENING SURFACE LOW PROPAGATING FROM THE SOUTHERN PLAINS
THROUGH NORTHERN ILLINOIS ON TOWARD CENTRAL LAKE MICHIGAN. MODEL
CONSISTENCY HAS BEEN ALL OVER THE PLACE FOR THIS TIME FRAME...SO
WILL HAVE TO WAIT AND SEE WHAT LATER RUNS COME UP WITH.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1138 AM CST SAT DEC 20 2014

LOW STRATUS/FOG/DRIZZLE WILL CONTINUE TO BE PROBLEMATIC THROUGH
THE PERIOD...ALTHOUGH GUIDANCE NOT RESOLVING LOW-LEVEL MOISTURE
WELL. AS A RESULT...OVERALL FORECAST CONFIDENCE IS LOW. 20.18Z TAFS
WILL CLOSELY FOLLOW RECENT OBSERVATIONAL TRENDS WITH IFR CEILINGS/
MVFR VISIBILITIES AT KRST AND MVFR CEILINGS/VFR VISIBILITIES AT
KLSE. LIFT INCREASES OVERNIGHT IN THE SHALLOW NEAR SURFACE SATURATED
LAYER...SO WILL DROP KRST CEILING BACK DOWN TO 200 FT AGL WITH
1/2SM IN FZGF/FZDZ BY 21.11Z. WILL ALSO DROP KLSE A CATEGORY BY
12.10Z...BUT KEEP OUT FZFG/FZDZ FOR NOW. FOR BOTH SITES...WILL
NEED TO CLOSELY WATCH OBSERVATIONAL TRENDS AS AMENDMENTS ARE
LIKELY THROUGH THE PERIOD.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ROGERS




000
FXUS63 KARX 201127
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
527 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CST SAT DEC 20 2014

THE MAIN FOCUS TODAY INTO TONIGHT CONTINUES TO BE ON THE
PROBABILITIES OF SEEING SOME FREEZING DRIZZLE AND FLURRIES.

CURRENTLY IN WEAK SOUTHERLY FLOW IN THE LOW LEVELS WITH A RIDGE
OVER THE CENTRAL GREAT LAKES AND LOW PRESSURE OVER THE EASTERN
ROCKIES. A CLOSED MID LEVEL LOW IS DRIFTING EAST ACROSS SOUTHERN
MANITOBA/ONTARIO WHILE A SHORT WAVE TROUGH DIVES SOUTH OF IT INTO
IOWA. SOME WEAK LOW LEVEL WARM AIR ADVECTION HAS LEAD TO SOME
LOWER STRATUS TO FORM ALONG AND EAST OF THE INTERSTATE 35
CORRIDOR. THERE IS JUST ENOUGH LIFT THERE TO PRODUCE SOME DRIZZLE AND
WITH TEMPERATURES BELOW FREEZING THERE HAS BEEN SOME SPOTS THAT
HAVE REPORTED SOME LIGHT GLAZING ON ROADS AND OTHER EXTERNAL
SURFACES. THIS WAA APPEARS TO WEAKEN FOR A PERIOD TODAY BEFORE
STRENGTHENING AGAIN TONIGHT ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN. COULD SEE SOME MORE OF THE SAME WITH THE COLUMN NOT
HAVING ANY ICE PRESENT AND SURFACE TEMPERATURES BELOW FREEZING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 339 AM CST SAT DEC 20 2014

QUITE THE MESSY PATTERN THROUGH THE WEEK WITH THURSDAY LOOKING THE
MOST LIKELY TO BE THE ONLY DRY ONE OF THE BUNCH. PRECIPITATION
SHOULD BECOME A BIT MORE WIDESPREAD...THOUGH STILL LIGHT...ON
SUNDAY AS A 700MB TROUGH INTERACTS WITH THE LOW LEVEL WARM AIR
ADVECTION. LIFT/MOISTURE LOOKS DEEP ENOUGH TO INTRODUCE SOME ICE
THOUGH IT ALSO BRINGS AN ABOVE FREEZING WARM LAYER IN AROUND 850MB
AS WELL. THEREFORE...PRECIPITATION TYPE IS A MESS FOR SUNDAY WITH
PERHAPS SOME FREEZING DRIZZLE TO START IN THE MORNING AS THE DRY
AIR BETWEEN 900-700MB IS TOO DEEP FOR SEEDER FEEDER TO WORK. AS
THE COLUMN STARTS TO SATURATE UNDER THE DEEPER LIFT IN THE
AFTERNOON...THE WARM LAYER MOVES IN WITH THE PRECIPITATION TYPE
LIKELY BEING SNOW OR SLEET INITIALLY. 20.00Z NAM/GFS SOUNDINGS
THEN INDICATE THAT AS THE PRECIPITATION FALLS THAT THE WARM LAYER
SHOULD COOL AGAIN WITH THE PRECIP TYPE CHANGING BACK TO SNOW. AS
THE WAVE THEN SHIFTS TO THE EAST SUNDAY NIGHT...IT APPEARS AS
THOUGH ICE IS LOST AND THAT THE PRECIPITATION TYPE THEN GOES BACK
TO BEING DRIZZLE.

WARMER AIR SHOULD THEN MOVE IN ON MONDAY AS A MORE POTENT TROUGH
DEVELOPS OVER THE DAKOTAS. THE 20.00Z NAM/ECMWF TRENDS APPEAR TO
BE PREFERRED OVER THE 20.00Z GFS WHICH IS MUCH FASTER WITH THE
CLOSED LOW. THE NAM/ECMWF SOLUTION BRINGS A BAND OF RAIN THROUGH
AND LIFTS IT TO THE NORTHEAST BY MONDAY EVENING WITH THE DRY SLOT
OF THE SYSTEM MOVING IN. THE GFS HAS THE SURFACE LOW MUCH FURTHER
SOUTH AS WELL AND WOULD KEEP PRECIP AROUND MUCH LONGER.
OVERALL...CONFIDENCE IN HOW THIS SYSTEM WILL PLAY OUT IS PRETTY
LOW AT THIS POINT.

COLDER AIR WILL MOVE IN BY MID WEEK WITH ANY PRECIPITATION
FALLING THROUGH THE REST OF THE WEEK EXPECTED TO BE SNOW. A SYSTEM
OF INTEREST IS WITH WHAT THE 20.00Z ECMWF IS SHOWING FOR THURSDAY
NIGHT THROUGH FRIDAY NIGHT. WHILE THE 20.00Z GFS ONLY HAS A WEAK
INVERTED TROUGH MOVING THROUGH THE ECMWF SHOWS A POTENT STORM
SYSTEM TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY REGION
WITH A DEEPENING SURFACE LOW PROPAGATING FROM THE SOUTHERN PLAINS
THROUGH NORTHERN ILLINOIS ON TOWARD CENTRAL LAKE MICHIGAN. MODEL
CONSISTENCY HAS BEEN ALL OVER THE PLACE FOR THIS TIME FRAME...SO
WILL HAVE TO WAIT AND SEE WHAT LATER RUNS COME UP WITH.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 527 AM CST SAT DEC 20 2014

WEAK TROUGH OF LOW PRESSURE OVER NORTHEAST IA EARLY THIS MORNING
WILL PUSH EAST OF THE AREA BY LATER THIS MORNING. THIS IS EXPECTED
TO BRING AN END TO LIGHT SNOW/FREEZING DRIZZLE ACTIVITY AROUND THE
AREA. OTHERWISE...PLAN ON IFR CONDITIONS AT KRST TO IMPROVE INTO
MVFR RANGE BY 18Z WHILE MVFR CIGS ARE EXPECTED TO CONTINUE AT
KLSE. ANOTHER TROUGH OF LOW PRESSURE MOVES TOWARD THE REGION
TONIGHT FOR ANOTHER BOUT OF FZDZ. KEPT OUT OF THE BODY OF THE
KRST/KLSE TAFS FOR NOW AS BEST SATURATION FOR FZDZ POTENTIAL
REMAINS JUST SOUTH OF THE SITES THROUGH 12Z. APPEARS KLSE REMAINS
MVFR THROUGH TONIGHT WHILE KRST IS EXPECTED TO SLIP INTO IFR ONCE
AGAIN AFTER 06Z.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS





000
FXUS63 KARX 201127
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
527 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CST SAT DEC 20 2014

THE MAIN FOCUS TODAY INTO TONIGHT CONTINUES TO BE ON THE
PROBABILITIES OF SEEING SOME FREEZING DRIZZLE AND FLURRIES.

CURRENTLY IN WEAK SOUTHERLY FLOW IN THE LOW LEVELS WITH A RIDGE
OVER THE CENTRAL GREAT LAKES AND LOW PRESSURE OVER THE EASTERN
ROCKIES. A CLOSED MID LEVEL LOW IS DRIFTING EAST ACROSS SOUTHERN
MANITOBA/ONTARIO WHILE A SHORT WAVE TROUGH DIVES SOUTH OF IT INTO
IOWA. SOME WEAK LOW LEVEL WARM AIR ADVECTION HAS LEAD TO SOME
LOWER STRATUS TO FORM ALONG AND EAST OF THE INTERSTATE 35
CORRIDOR. THERE IS JUST ENOUGH LIFT THERE TO PRODUCE SOME DRIZZLE AND
WITH TEMPERATURES BELOW FREEZING THERE HAS BEEN SOME SPOTS THAT
HAVE REPORTED SOME LIGHT GLAZING ON ROADS AND OTHER EXTERNAL
SURFACES. THIS WAA APPEARS TO WEAKEN FOR A PERIOD TODAY BEFORE
STRENGTHENING AGAIN TONIGHT ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN. COULD SEE SOME MORE OF THE SAME WITH THE COLUMN NOT
HAVING ANY ICE PRESENT AND SURFACE TEMPERATURES BELOW FREEZING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 339 AM CST SAT DEC 20 2014

QUITE THE MESSY PATTERN THROUGH THE WEEK WITH THURSDAY LOOKING THE
MOST LIKELY TO BE THE ONLY DRY ONE OF THE BUNCH. PRECIPITATION
SHOULD BECOME A BIT MORE WIDESPREAD...THOUGH STILL LIGHT...ON
SUNDAY AS A 700MB TROUGH INTERACTS WITH THE LOW LEVEL WARM AIR
ADVECTION. LIFT/MOISTURE LOOKS DEEP ENOUGH TO INTRODUCE SOME ICE
THOUGH IT ALSO BRINGS AN ABOVE FREEZING WARM LAYER IN AROUND 850MB
AS WELL. THEREFORE...PRECIPITATION TYPE IS A MESS FOR SUNDAY WITH
PERHAPS SOME FREEZING DRIZZLE TO START IN THE MORNING AS THE DRY
AIR BETWEEN 900-700MB IS TOO DEEP FOR SEEDER FEEDER TO WORK. AS
THE COLUMN STARTS TO SATURATE UNDER THE DEEPER LIFT IN THE
AFTERNOON...THE WARM LAYER MOVES IN WITH THE PRECIPITATION TYPE
LIKELY BEING SNOW OR SLEET INITIALLY. 20.00Z NAM/GFS SOUNDINGS
THEN INDICATE THAT AS THE PRECIPITATION FALLS THAT THE WARM LAYER
SHOULD COOL AGAIN WITH THE PRECIP TYPE CHANGING BACK TO SNOW. AS
THE WAVE THEN SHIFTS TO THE EAST SUNDAY NIGHT...IT APPEARS AS
THOUGH ICE IS LOST AND THAT THE PRECIPITATION TYPE THEN GOES BACK
TO BEING DRIZZLE.

WARMER AIR SHOULD THEN MOVE IN ON MONDAY AS A MORE POTENT TROUGH
DEVELOPS OVER THE DAKOTAS. THE 20.00Z NAM/ECMWF TRENDS APPEAR TO
BE PREFERRED OVER THE 20.00Z GFS WHICH IS MUCH FASTER WITH THE
CLOSED LOW. THE NAM/ECMWF SOLUTION BRINGS A BAND OF RAIN THROUGH
AND LIFTS IT TO THE NORTHEAST BY MONDAY EVENING WITH THE DRY SLOT
OF THE SYSTEM MOVING IN. THE GFS HAS THE SURFACE LOW MUCH FURTHER
SOUTH AS WELL AND WOULD KEEP PRECIP AROUND MUCH LONGER.
OVERALL...CONFIDENCE IN HOW THIS SYSTEM WILL PLAY OUT IS PRETTY
LOW AT THIS POINT.

COLDER AIR WILL MOVE IN BY MID WEEK WITH ANY PRECIPITATION
FALLING THROUGH THE REST OF THE WEEK EXPECTED TO BE SNOW. A SYSTEM
OF INTEREST IS WITH WHAT THE 20.00Z ECMWF IS SHOWING FOR THURSDAY
NIGHT THROUGH FRIDAY NIGHT. WHILE THE 20.00Z GFS ONLY HAS A WEAK
INVERTED TROUGH MOVING THROUGH THE ECMWF SHOWS A POTENT STORM
SYSTEM TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY REGION
WITH A DEEPENING SURFACE LOW PROPAGATING FROM THE SOUTHERN PLAINS
THROUGH NORTHERN ILLINOIS ON TOWARD CENTRAL LAKE MICHIGAN. MODEL
CONSISTENCY HAS BEEN ALL OVER THE PLACE FOR THIS TIME FRAME...SO
WILL HAVE TO WAIT AND SEE WHAT LATER RUNS COME UP WITH.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 527 AM CST SAT DEC 20 2014

WEAK TROUGH OF LOW PRESSURE OVER NORTHEAST IA EARLY THIS MORNING
WILL PUSH EAST OF THE AREA BY LATER THIS MORNING. THIS IS EXPECTED
TO BRING AN END TO LIGHT SNOW/FREEZING DRIZZLE ACTIVITY AROUND THE
AREA. OTHERWISE...PLAN ON IFR CONDITIONS AT KRST TO IMPROVE INTO
MVFR RANGE BY 18Z WHILE MVFR CIGS ARE EXPECTED TO CONTINUE AT
KLSE. ANOTHER TROUGH OF LOW PRESSURE MOVES TOWARD THE REGION
TONIGHT FOR ANOTHER BOUT OF FZDZ. KEPT OUT OF THE BODY OF THE
KRST/KLSE TAFS FOR NOW AS BEST SATURATION FOR FZDZ POTENTIAL
REMAINS JUST SOUTH OF THE SITES THROUGH 12Z. APPEARS KLSE REMAINS
MVFR THROUGH TONIGHT WHILE KRST IS EXPECTED TO SLIP INTO IFR ONCE
AGAIN AFTER 06Z.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS




000
FXUS63 KARX 200939
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
339 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CST SAT DEC 20 2014

THE MAIN FOCUS TODAY INTO TONIGHT CONTINUES TO BE ON THE
PROBABILITIES OF SEEING SOME FREEZING DRIZZLE AND FLURRIES.

CURRENTLY IN WEAK SOUTHERLY FLOW IN THE LOW LEVELS WITH A RIDGE
OVER THE CENTRAL GREAT LAKES AND LOW PRESSURE OVER THE EASTERN
ROCKIES. A CLOSED MID LEVEL LOW IS DRIFTING EAST ACROSS SOUTHERN
MANITOBA/ONTARIO WHILE A SHORT WAVE TROUGH DIVES SOUTH OF IT INTO
IOWA. SOME WEAK LOW LEVEL WARM AIR ADVECTION HAS LEAD TO SOME
LOWER STRATUS TO FORM ALONG AND EAST OF THE INTERSTATE 35
CORRIDOR. THERE IS JUST ENOUGH LIFT THERE TO PRODUCE SOME DRIZZLE AND
WITH TEMPERATURES BELOW FREEZING THERE HAS BEEN SOME SPOTS THAT
HAVE REPORTED SOME LIGHT GLAZING ON ROADS AND OTHER EXTERNAL
SURFACES. THIS WAA APPEARS TO WEAKEN FOR A PERIOD TODAY BEFORE
STRENGTHENING AGAIN TONIGHT ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN. COULD SEE SOME MORE OF THE SAME WITH THE COLUMN NOT
HAVING ANY ICE PRESENT AND SURFACE TEMPERATURES BELOW FREEZING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 339 AM CST SAT DEC 20 2014

QUITE THE MESSY PATTERN THROUGH THE WEEK WITH THURSDAY LOOKING THE
MOST LIKELY TO BE THE ONLY DRY ONE OF THE BUNCH. PRECIPITATION
SHOULD BECOME A BIT MORE WIDESPREAD...THOUGH STILL LIGHT...ON
SUNDAY AS A 700MB TROUGH INTERACTS WITH THE LOW LEVEL WARM AIR
ADVECTION. LIFT/MOISTURE LOOKS DEEP ENOUGH TO INTRODUCE SOME ICE
THOUGH IT ALSO BRINGS AN ABOVE FREEZING WARM LAYER IN AROUND 850MB
AS WELL. THEREFORE...PRECIPITATION TYPE IS A MESS FOR SUNDAY WITH
PERHAPS SOME FREEZING DRIZZLE TO START IN THE MORNING AS THE DRY
AIR BETWEEN 900-700MB IS TOO DEEP FOR SEEDER FEEDER TO WORK. AS
THE COLUMN STARTS TO SATURATE UNDER THE DEEPER LIFT IN THE
AFTERNOON...THE WARM LAYER MOVES IN WITH THE PRECIPITATION TYPE
LIKELY BEING SNOW OR SLEET INITIALLY. 20.00Z NAM/GFS SOUNDINGS
THEN INDICATE THAT AS THE PRECIPITATION FALLS THAT THE WARM LAYER
SHOULD COOL AGAIN WITH THE PRECIP TYPE CHANGING BACK TO SNOW. AS
THE WAVE THEN SHIFTS TO THE EAST SUNDAY NIGHT...IT APPEARS AS
THOUGH ICE IS LOST AND THAT THE PRECIPITATION TYPE THEN GOES BACK
TO BEING DRIZZLE.

WARMER AIR SHOULD THEN MOVE IN ON MONDAY AS A MORE POTENT TROUGH
DEVELOPS OVER THE DAKOTAS. THE 20.00Z NAM/ECMWF TRENDS APPEAR TO
BE PREFERRED OVER THE 20.00Z GFS WHICH IS MUCH FASTER WITH THE
CLOSED LOW. THE NAM/ECMWF SOLUTION BRINGS A BAND OF RAIN THROUGH
AND LIFTS IT TO THE NORTHEAST BY MONDAY EVENING WITH THE DRY SLOT
OF THE SYSTEM MOVING IN. THE GFS HAS THE SURFACE LOW MUCH FURTHER
SOUTH AS WELL AND WOULD KEEP PRECIP AROUND MUCH LONGER.
OVERALL...CONFIDENCE IN HOW THIS SYSTEM WILL PLAY OUT IS PRETTY
LOW AT THIS POINT.

COLDER AIR WILL MOVE IN BY MID WEEK WITH ANY PRECIPITATION
FALLING THROUGH THE REST OF THE WEEK EXPECTED TO BE SNOW. A SYSTEM
OF INTEREST IS WITH WHAT THE 20.00Z ECMWF IS SHOWING FOR THURSDAY
NIGHT THROUGH FRIDAY NIGHT. WHILE THE 20.00Z GFS ONLY HAS A WEAK
INVERTED TROUGH MOVING THROUGH THE ECMWF SHOWS A POTENT STORM
SYSTEM TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY REGION
WITH A DEEPENING SURFACE LOW PROPAGATING FROM THE SOUTHERN PLAINS
THROUGH NORTHERN ILLINOIS ON TOWARD CENTRAL LAKE MICHIGAN. MODEL
CONSISTENCY HAS BEEN ALL OVER THE PLACE FOR THIS TIME FRAME...SO
WILL HAVE TO WAIT AND SEE WHAT LATER RUNS COME UP WITH.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM CST FRI DEC 19 2014

CEILINGS HAVE STAYED UP A LITTLE HIGHER THAN EXPECTED THIS
EVENING...WHICH MIGHT BE A FUNCTION OF NOT BEING IN THE HIGHER
MOISTURE RETURN TAKING PLACE ALONG AND WEST OF I-35. A SOUTH TO
SOUTHEAST WIND TO THIS POINT HAS HELPED KEEP LOW CEILINGS OFF TO
THE WEST. HOWEVER...JUST ABOVE THE GROUND THE WINDS ARE FORECAST
TO TURN MORE TO THE SOUTHWEST OVER THE NEXT FEW HOURS. AS A
RESULT...ANTICIPATING RST TO LOWER FROM MVFR TO IFR BY 10Z...ALONG
WITH THE FORMATION OF SOME MVFR BR. AT LSE...CONDITIONS WILL STAY
MVFR...BUT CEILINGS SHOULD DROP SOME. TOWARDS THE MIDDLE OF THE
DAY...DAYTIME HEATING PLUS THE FLOW JUST ABOVE THE GROUND BACKING
MORE SOUTHERLY SHOULD ALLOW CEILINGS TO COME UP SOME...AT LEAST
ENOUGH TO PULL RST OUT OF IFR. THE FLOW STAYS CONSISTENT INTO THE
EVENING...THUS HELD CEILINGS STEADY. ITS POSSIBLE RST FALLS TO
IFR LATE IN THE EVENING...BUT CONFIDENCE IS TOO LOW TO INCLUDE AT
THIS TIME.


&&

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

$$

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





000
FXUS63 KARX 200939
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
339 AM CST SAT DEC 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CST SAT DEC 20 2014

THE MAIN FOCUS TODAY INTO TONIGHT CONTINUES TO BE ON THE
PROBABILITIES OF SEEING SOME FREEZING DRIZZLE AND FLURRIES.

CURRENTLY IN WEAK SOUTHERLY FLOW IN THE LOW LEVELS WITH A RIDGE
OVER THE CENTRAL GREAT LAKES AND LOW PRESSURE OVER THE EASTERN
ROCKIES. A CLOSED MID LEVEL LOW IS DRIFTING EAST ACROSS SOUTHERN
MANITOBA/ONTARIO WHILE A SHORT WAVE TROUGH DIVES SOUTH OF IT INTO
IOWA. SOME WEAK LOW LEVEL WARM AIR ADVECTION HAS LEAD TO SOME
LOWER STRATUS TO FORM ALONG AND EAST OF THE INTERSTATE 35
CORRIDOR. THERE IS JUST ENOUGH LIFT THERE TO PRODUCE SOME DRIZZLE AND
WITH TEMPERATURES BELOW FREEZING THERE HAS BEEN SOME SPOTS THAT
HAVE REPORTED SOME LIGHT GLAZING ON ROADS AND OTHER EXTERNAL
SURFACES. THIS WAA APPEARS TO WEAKEN FOR A PERIOD TODAY BEFORE
STRENGTHENING AGAIN TONIGHT ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN. COULD SEE SOME MORE OF THE SAME WITH THE COLUMN NOT
HAVING ANY ICE PRESENT AND SURFACE TEMPERATURES BELOW FREEZING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 339 AM CST SAT DEC 20 2014

QUITE THE MESSY PATTERN THROUGH THE WEEK WITH THURSDAY LOOKING THE
MOST LIKELY TO BE THE ONLY DRY ONE OF THE BUNCH. PRECIPITATION
SHOULD BECOME A BIT MORE WIDESPREAD...THOUGH STILL LIGHT...ON
SUNDAY AS A 700MB TROUGH INTERACTS WITH THE LOW LEVEL WARM AIR
ADVECTION. LIFT/MOISTURE LOOKS DEEP ENOUGH TO INTRODUCE SOME ICE
THOUGH IT ALSO BRINGS AN ABOVE FREEZING WARM LAYER IN AROUND 850MB
AS WELL. THEREFORE...PRECIPITATION TYPE IS A MESS FOR SUNDAY WITH
PERHAPS SOME FREEZING DRIZZLE TO START IN THE MORNING AS THE DRY
AIR BETWEEN 900-700MB IS TOO DEEP FOR SEEDER FEEDER TO WORK. AS
THE COLUMN STARTS TO SATURATE UNDER THE DEEPER LIFT IN THE
AFTERNOON...THE WARM LAYER MOVES IN WITH THE PRECIPITATION TYPE
LIKELY BEING SNOW OR SLEET INITIALLY. 20.00Z NAM/GFS SOUNDINGS
THEN INDICATE THAT AS THE PRECIPITATION FALLS THAT THE WARM LAYER
SHOULD COOL AGAIN WITH THE PRECIP TYPE CHANGING BACK TO SNOW. AS
THE WAVE THEN SHIFTS TO THE EAST SUNDAY NIGHT...IT APPEARS AS
THOUGH ICE IS LOST AND THAT THE PRECIPITATION TYPE THEN GOES BACK
TO BEING DRIZZLE.

WARMER AIR SHOULD THEN MOVE IN ON MONDAY AS A MORE POTENT TROUGH
DEVELOPS OVER THE DAKOTAS. THE 20.00Z NAM/ECMWF TRENDS APPEAR TO
BE PREFERRED OVER THE 20.00Z GFS WHICH IS MUCH FASTER WITH THE
CLOSED LOW. THE NAM/ECMWF SOLUTION BRINGS A BAND OF RAIN THROUGH
AND LIFTS IT TO THE NORTHEAST BY MONDAY EVENING WITH THE DRY SLOT
OF THE SYSTEM MOVING IN. THE GFS HAS THE SURFACE LOW MUCH FURTHER
SOUTH AS WELL AND WOULD KEEP PRECIP AROUND MUCH LONGER.
OVERALL...CONFIDENCE IN HOW THIS SYSTEM WILL PLAY OUT IS PRETTY
LOW AT THIS POINT.

COLDER AIR WILL MOVE IN BY MID WEEK WITH ANY PRECIPITATION
FALLING THROUGH THE REST OF THE WEEK EXPECTED TO BE SNOW. A SYSTEM
OF INTEREST IS WITH WHAT THE 20.00Z ECMWF IS SHOWING FOR THURSDAY
NIGHT THROUGH FRIDAY NIGHT. WHILE THE 20.00Z GFS ONLY HAS A WEAK
INVERTED TROUGH MOVING THROUGH THE ECMWF SHOWS A POTENT STORM
SYSTEM TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY REGION
WITH A DEEPENING SURFACE LOW PROPAGATING FROM THE SOUTHERN PLAINS
THROUGH NORTHERN ILLINOIS ON TOWARD CENTRAL LAKE MICHIGAN. MODEL
CONSISTENCY HAS BEEN ALL OVER THE PLACE FOR THIS TIME FRAME...SO
WILL HAVE TO WAIT AND SEE WHAT LATER RUNS COME UP WITH.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM CST FRI DEC 19 2014

CEILINGS HAVE STAYED UP A LITTLE HIGHER THAN EXPECTED THIS
EVENING...WHICH MIGHT BE A FUNCTION OF NOT BEING IN THE HIGHER
MOISTURE RETURN TAKING PLACE ALONG AND WEST OF I-35. A SOUTH TO
SOUTHEAST WIND TO THIS POINT HAS HELPED KEEP LOW CEILINGS OFF TO
THE WEST. HOWEVER...JUST ABOVE THE GROUND THE WINDS ARE FORECAST
TO TURN MORE TO THE SOUTHWEST OVER THE NEXT FEW HOURS. AS A
RESULT...ANTICIPATING RST TO LOWER FROM MVFR TO IFR BY 10Z...ALONG
WITH THE FORMATION OF SOME MVFR BR. AT LSE...CONDITIONS WILL STAY
MVFR...BUT CEILINGS SHOULD DROP SOME. TOWARDS THE MIDDLE OF THE
DAY...DAYTIME HEATING PLUS THE FLOW JUST ABOVE THE GROUND BACKING
MORE SOUTHERLY SHOULD ALLOW CEILINGS TO COME UP SOME...AT LEAST
ENOUGH TO PULL RST OUT OF IFR. THE FLOW STAYS CONSISTENT INTO THE
EVENING...THUS HELD CEILINGS STEADY. ITS POSSIBLE RST FALLS TO
IFR LATE IN THE EVENING...BUT CONFIDENCE IS TOO LOW TO INCLUDE AT
THIS TIME.


&&

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

$$

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




000
FXUS63 KARX 200509
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1109 PM CST FRI DEC 19 2014

.SHORT TERM...(TONIGHT THRU SATURDAY NIGHT)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FORECAST CONCERNS THIS PERIOD...LOW LEVEL MOISTURE/CLOUDS AND
ANY -FZDZ CHANCES...TEMPERATURES.

18Z DATA ANALYSIS HAD A BROAD AREA OF HIGH PRESSURE FROM EASTERN ONT
SOUTHWEST TO MO. 19.12Z RAOBS SHOWED A RATHER STRONG INVERSION NEAR
900MB ACROSS THE REGION...WITH PLENTY OF MOISTURE TRAPPED IN/UNDER
IT PRODUCING RATHER WIDESPREAD LOWER STRATUS CLOUDS ACROSS THE
REGION. SOME BREAKS IN THE CLOUDS OVER PARTS OF IL/EASTERN WI.
OTHERWISE DEVELOPING SOUTHEAST TO SOUTH FLOW ON THE WEST SIDE OF THE
RIDGE AXIS WAS ADVECTING MORE MOISTURE NORTHWARD INTO IA/MN. WITH
LACK OF SNOW COVER...TEMPS ACTUALLY WARMING A BIT TODAY UNDER THE
CLOUDS IN THE DEVELOPING SOUTHERLY WARM ADVECTION FLOW.

19.12Z MODELS LOOK TO HAVE INITIALIZED WELL...THOUGH ALL WERE ABOUT
1MB TOO HIGH WITH SFC PRESSURES IN THE BROAD HIGH FROM ONT TO THE
MID MS VALLEY. SOLUTIONS SIMILAR FOR TONIGHT THRU SAT NIGHT AND
CONVERGING TOWARD A TIGHTER COMPROMISE OF THEIR EARLIER RUNS AS
ONE SHORTWAVE PASSES SOUTH OF THE AREA TONIGHT AND ANOTHER MOVES
INTO MN SAT NIGHT. SHORT-TERM FCST CONFIDENCE IS GENERALLY GOOD
THIS CYCLE.

IN THE SHORT TERM...THE MAIN CONCERN TONIGHT THRU SAT NIGHT IS THE
DEPTH OF THE LOWER LEVEL MOISTURE/STRATUS AND EXTENT OF ANY LIFT
IN/JUST ABOVE THE MOISTURE LAYER. THIS MOISTURE REMAINS TRAPPED
UNDER AN INVERSION AROUND 850MB TONIGHT AND AROUND 900MB SAT NIGHT.
DEEPEST MOISTURE IS OVER THE FCST AREA LATE THIS AFTERNOON/EVENING
BUT MOST CLOUD BASES IN THE 1500-2500 FT RANGE WITH SFC TEMP-DEW
POINT SPREADS OF 5F TO 10F. THIS NOT OVERLY CONDUCIVE TO TO -DZ/
-FZDZ AND REMOVED ANY -FZDZ MENTION THRU THIS EVENING. WEAK/MDT
925MB WARM ADVECTION AND 280-285K PERSIST ACROSS THE AREA TONIGHT
THRU SAT NIGHT. SOME OF THE STRONGER OF THIS SAT NIGHT AS THE 925MB
FLOW INCREASE TO AROUND 20KTS. SFC-925MB SATURATION INCREASES THRU
TONIGHT...WITH LOWERING CIGS AND TEMP-DEW POINT SPREADS. WILL
CONTINUE THE PATCHY -FZDZ SPREADING ACROSS MUCH OF THE FCST AREA
DURING THE LATE EVENING/OVERNIGHT HOURS INTO EARLY SAT MORNING.
ADDED A PATCHY FOG MENTION OVERNIGHT INTO SAT MORNING AS WELL. LEFT
THE BULK OF SAT/SAT EVENING DRY BUT CANNOT RULE OUT ISOLATED -DZ/
-FZDZ AND PATCHY FOG. CONTINUED THE PATCHY -FZDZ MENTION LATER SAT
NIGHT WITH THE INCREASE OF LIFT LATE BUT DID REMOVE ANY -SN MENTION
AS TOP OF THE MOISTURE COLUMN LATER SAT NIGHT WOULD ONLY BE ABOUT
-5C AT THE COLDEST WITH NO ICE IN THE CLOUDS. ADDED SOME FOG FOR
THIS PERIOD AS AN INCREASINGLY MOIST SFC-925MB AIRMASS IS PUSHED
NORTHWARD OVER THE COLD LANDSCAPE. FAVORED WARMER OF GUIDANCE LOWS
TONIGHT/SAT NIGHT WITH THE THICKENING LOW CLOUDS AND A BLEND OF
GUIDANCE HIGHS FOR SAT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FCST CONCERNS FOR SUN THRU MON NIGHT...PRECIP TYPES/CHANCES AS
THE TROUGH/LOW DEEPEN AND APPROACH...TEMPERATURES.

19.12Z MODELS SHOW A TIGHTENING CONSENSUS AS STRONG SHORTWAVE ENERGY
TOPS THE WESTERN NOAM RIDGING SUN THEN DROPS INTO THE CENTRAL/
NORTHERN PLAINS SUN NIGHT/MON. THIS CONSENSUS FAVORS SLOWER/
STRONGER OF THE EARLIER RUNS AT 00Z TUE. GOOD AGREEMENT AMONG GFS/
ECMWF/NAM FOR A 500MB LOW NEAR KFSD BY 00Z TUE...MIGRATING TOWARD
KDSM BY 12Z TUE. CAN-GEM MORE PROGRESSIVE/FURTHER NORTH AND
APPEARS AS AN OUTLIER BY MON NIGHT. GIVEN GOOD/TIGHT CONSENSUS
AMONG NAM/ECMWF/ GFS THRU 12Z TUE...FCST CONFIDENCE FOR SUN THRU
MON NIGHT REMAINS GENERALLY GOOD.

FALLING HGTS AND STRENGTHENING LOW PRESSURE IN THE NORTHERN PLAINS
CONTINUES THE SOUTH/SOUTHWEST LOW LEVEL FLOW INTO THE AREA SUN/SUN
NIGHT. SFC THRU 850MB LOW REMAINS NORTHWEST OF THE FCST AREA THRU
00Z TUE. THIS PERSISTENT SOUTH/SOUTHWEST WARM ADVECTION FLOW AHEAD
OF THE LOW WARMS THE SFC-925MB LAYER TO NEAR/ABOVE 0C BY MON/MON
NIGHT. DEPTH OF MOISTURE THE AREA STARTS TO INCREASE SUN ALONG WITH
THE STRENGTH/DEPTH OF THE FORCING/LIFT. MOISTURE/LIFT INCREASE EVEN
MORE FOR SUN NIGHT THRU MON NIGHT WITH PRECIP BECOMING LIKELY FOR
MUCH OF THE AREA MON/MON NIGHT. TRANSITIONED ANY PRECIP FROM -DZ
TO -RA SUN MORNING WITH DEEPER MOISTURE AND ONE STRONGER SURGE OF
850- 700MB WARM ADVECTION LIFTING ACROSS THE AREA. BIT OF A LULL
IN THE LIFT SUN NIGHT WITH THE INCREASE OF DYNAMIC LIFT/PV
ADVECTION AHEAD OF THE TROUGH/SHORTWAVE MOVING ACROSS MON/MON
NIGHT. RAISED PRECIP CHANCES MON INTO MON NIGHT. ADDED PATCHY FOG
FOR SUN NIGHT/MON MORNING AS WELL WITH INCREASING DEW POINTS OVER
THE COLD GROUND. TRENDED PRECIP SUN NIGHT THRU MON NIGHT TOWARD
MORE -RA AS MODEL SOUNDINGS AND X-SECTIONS FOR THIS PERIOD SHOWING
AT LEAST THE SFC- 900MB LAYER WARMING INTO THE 0C TO +3C RANGE...
ESPECIALLY OVER THE CENTRAL/SOUTH PARTS OF THE FCST AREA. LINGERED
A -SN CHANCE MAINLY DURING THE NIGHTTIME/EARLY MORNING HOURS WITH
A COOLER BOUNDARY LAYER AND ANY HEAVIER PRECIP RATES IF THEY OCCUR
CAPABLE OF COOLING THE COLUMN ENOUGH FOR SNOWFLAKES TO REACH THE
GROUND. WILL ALSO HAVE TO WATCH THE LATE NIGHT/EARLY MORNING HOURS
OF SUN/MON NIGHTS FOR -FZRA ON COLD GROUND SURFACES. USED A BLEND
OF THE GUIDANCE HIGHS/ LOWS FOR SUN THRU MON NIGHT...RAISING LOWS
A BIT SUN NIGHT WITH THE SOUTHERLY BOUNDARY LAYER FLOW/THICK LOW
CLOUDS OVER THE AREA.

FOR TUESDAY THRU FRIDAY...DAYS 4 TO 7...

MAIN FORECAST CONCERNS THIS PERIOD...PRECIP CHANCES/TYPES TUE/WED
AND AGAIN FRI...TEMPERATURES.

MEDIUM RANGE MODEL RUNS OF 19.00Z/19.12Z IN QUITE GOOD AGREEMENT TUE
WITH THE TROUGH DEEPENING OVER THE CENTRAL CONUS. TREND FAVORS
SLOWER/STRONGER OF THE EARLIER RUNS. CONSISTENCY REMAINS GOOD FOR
THE TROUGH TO BE PROGRESSIVE INTO THE EASTERN CONUS WED/THU AS
STRONG ENERGY ROTATES UP THE EAST SIDE OF THE TROUGH. IMPROVING
SIGNAL FOR SHORTWAVE RIDGING TO BUILD OVER THE MID/UPPER MS VALLEY
FOR CHRISTMAS DAY...AS ONE TROUGH LIFTS INTO THE CAN MARITIMES AND
MORE ENERGY DIGS INTO THE CENTRAL/SOUTHERN ROCKIES. POTENTIAL FOR
SOME PORTION OF THE ENERGY TO LIFT TOWARD/INTO THE MID/UPPER MS
VALLEY FRI. PLENTY OF SPREAD AMONG THE MODELS AND ENSEMBLE
MEMBERS WITH THE DETAILS BY DAY 7. CONFIDENCE IN THE DAY 4-7
PERIOD IS AVERAGE TO GOOD TUE-THU THEN AVERAGE TO BELOW FOR FRI.

IMPROVING MODEL CONSENSUS FOR THE SFC-700MB LOW TO BE OCCLUDING/
AS IT MOVES ACROSS THE UPPER MIDWEST TUE. FORCING/LIFT OVER THE
FCST AREA WEAKENS THRU TUE/TUE NIGHT WITH THE MOISTURE CONVEYOR
BEING PUSHED FURTHER FROM THE AREA BY THE OCCLUSION. COLUMN DOES
COOL TUE AS THE OCCLUDING LOW/MID LEVEL TROUGH AXIS PASS. HIGHER
CHANCES OF PRECIP TUE/TUE NIGHT AS A DEFORMATION BAND WOULD
ROTATE ACROSS THE AREA. MIX OF -RA/-SN TUE MORNING GIVING WAY TO
-SN FOR LATE TUE/TUE NIGHT. STRONG ENERGY IN THE SOUTHERN PORTION
OF THE LONGWAVE TROUGH ROTATING UP THE EASTERN SEABOARD WED DRAGS
THE MID LEVEL LOW INTO THE EASTERN GREAT LAKES BY WED NIGHT...
SPREADING DRYING NORTHWEST 850-500MB FLOW OVER THE REGION. ANY
LINGERING -SN LOOKING TO TAPER OFF FROM SOUTHWEST TO NORTHEAST
WED/WED EVENING. SFC THRU MID LEVEL RIDGING PROGGED TO SLIDE
ACROSS THE UPPER MIDWEST THU...WITH OUR BEST SHOT AT SOME SUNSHINE
NEXT WEEK ON CHRISTMAS DAY. CONFIDENCE AVERAGE AT BEST FRI BUT
LATEST DETERMINISTIC MODEL RUNS WOULD LIFT A PORTION OF THE
ROCKIES ENERGY INTO THE UPPER MIDWEST AT THE END OF THE WEEK.
PLENTY OF LOWER LEVEL DETAIL DIFFERENCES BY FRI WITH ANY
POTENTIAL SFC LOW TRACK/STRENGTH AND HOW MUCH WARM AIR IS DRAWN
NORTH AHEAD OF THE SYSTEM FOR PRECIP TYPE ISSUES. WILL STAY WITH
THE MODEL/ENSEMBLE CONSENSUS ON FRI FOR NOW. MODEL/ENSEMBLE
CONSENSUS OF HIGHS/LOWS FOR TUE-FRI SEEMS TO HAVE THEM WELL
TRENDED AS WELL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM CST FRI DEC 19 2014

CEILINGS HAVE STAYED UP A LITTLE HIGHER THAN EXPECTED THIS
EVENING...WHICH MIGHT BE A FUNCTION OF NOT BEING IN THE HIGHER
MOISTURE RETURN TAKING PLACE ALONG AND WEST OF I-35. A SOUTH TO
SOUTHEAST WIND TO THIS POINT HAS HELPED KEEP LOW CEILINGS OFF TO
THE WEST. HOWEVER...JUST ABOVE THE GROUND THE WINDS ARE FORECAST
TO TURN MORE TO THE SOUTHWEST OVER THE NEXT FEW HOURS. AS A
RESULT...ANTICIPATING RST TO LOWER FROM MVFR TO IFR BY 10Z...ALONG
WITH THE FORMATION OF SOME MVFR BR. AT LSE...CONDITIONS WILL STAY
MVFR...BUT CEILINGS SHOULD DROP SOME. TOWARDS THE MIDDLE OF THE
DAY...DAYTIME HEATING PLUS THE FLOW JUST ABOVE THE GROUND BACKING
MORE SOUTHERLY SHOULD ALLOW CEILINGS TO COME UP SOME...AT LEAST
ENOUGH TO PULL RST OUT OF IFR. THE FLOW STAYS CONSISTENT INTO THE
EVENING...THUS HELD CEILINGS STEADY. ITS POSSIBLE RST FALLS TO
IFR LATE IN THE EVENING...BUT CONFIDENCE IS TOO LOW TO INCLUDE AT
THIS TIME.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ





000
FXUS63 KARX 200509
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1109 PM CST FRI DEC 19 2014

.SHORT TERM...(TONIGHT THRU SATURDAY NIGHT)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FORECAST CONCERNS THIS PERIOD...LOW LEVEL MOISTURE/CLOUDS AND
ANY -FZDZ CHANCES...TEMPERATURES.

18Z DATA ANALYSIS HAD A BROAD AREA OF HIGH PRESSURE FROM EASTERN ONT
SOUTHWEST TO MO. 19.12Z RAOBS SHOWED A RATHER STRONG INVERSION NEAR
900MB ACROSS THE REGION...WITH PLENTY OF MOISTURE TRAPPED IN/UNDER
IT PRODUCING RATHER WIDESPREAD LOWER STRATUS CLOUDS ACROSS THE
REGION. SOME BREAKS IN THE CLOUDS OVER PARTS OF IL/EASTERN WI.
OTHERWISE DEVELOPING SOUTHEAST TO SOUTH FLOW ON THE WEST SIDE OF THE
RIDGE AXIS WAS ADVECTING MORE MOISTURE NORTHWARD INTO IA/MN. WITH
LACK OF SNOW COVER...TEMPS ACTUALLY WARMING A BIT TODAY UNDER THE
CLOUDS IN THE DEVELOPING SOUTHERLY WARM ADVECTION FLOW.

19.12Z MODELS LOOK TO HAVE INITIALIZED WELL...THOUGH ALL WERE ABOUT
1MB TOO HIGH WITH SFC PRESSURES IN THE BROAD HIGH FROM ONT TO THE
MID MS VALLEY. SOLUTIONS SIMILAR FOR TONIGHT THRU SAT NIGHT AND
CONVERGING TOWARD A TIGHTER COMPROMISE OF THEIR EARLIER RUNS AS
ONE SHORTWAVE PASSES SOUTH OF THE AREA TONIGHT AND ANOTHER MOVES
INTO MN SAT NIGHT. SHORT-TERM FCST CONFIDENCE IS GENERALLY GOOD
THIS CYCLE.

IN THE SHORT TERM...THE MAIN CONCERN TONIGHT THRU SAT NIGHT IS THE
DEPTH OF THE LOWER LEVEL MOISTURE/STRATUS AND EXTENT OF ANY LIFT
IN/JUST ABOVE THE MOISTURE LAYER. THIS MOISTURE REMAINS TRAPPED
UNDER AN INVERSION AROUND 850MB TONIGHT AND AROUND 900MB SAT NIGHT.
DEEPEST MOISTURE IS OVER THE FCST AREA LATE THIS AFTERNOON/EVENING
BUT MOST CLOUD BASES IN THE 1500-2500 FT RANGE WITH SFC TEMP-DEW
POINT SPREADS OF 5F TO 10F. THIS NOT OVERLY CONDUCIVE TO TO -DZ/
-FZDZ AND REMOVED ANY -FZDZ MENTION THRU THIS EVENING. WEAK/MDT
925MB WARM ADVECTION AND 280-285K PERSIST ACROSS THE AREA TONIGHT
THRU SAT NIGHT. SOME OF THE STRONGER OF THIS SAT NIGHT AS THE 925MB
FLOW INCREASE TO AROUND 20KTS. SFC-925MB SATURATION INCREASES THRU
TONIGHT...WITH LOWERING CIGS AND TEMP-DEW POINT SPREADS. WILL
CONTINUE THE PATCHY -FZDZ SPREADING ACROSS MUCH OF THE FCST AREA
DURING THE LATE EVENING/OVERNIGHT HOURS INTO EARLY SAT MORNING.
ADDED A PATCHY FOG MENTION OVERNIGHT INTO SAT MORNING AS WELL. LEFT
THE BULK OF SAT/SAT EVENING DRY BUT CANNOT RULE OUT ISOLATED -DZ/
-FZDZ AND PATCHY FOG. CONTINUED THE PATCHY -FZDZ MENTION LATER SAT
NIGHT WITH THE INCREASE OF LIFT LATE BUT DID REMOVE ANY -SN MENTION
AS TOP OF THE MOISTURE COLUMN LATER SAT NIGHT WOULD ONLY BE ABOUT
-5C AT THE COLDEST WITH NO ICE IN THE CLOUDS. ADDED SOME FOG FOR
THIS PERIOD AS AN INCREASINGLY MOIST SFC-925MB AIRMASS IS PUSHED
NORTHWARD OVER THE COLD LANDSCAPE. FAVORED WARMER OF GUIDANCE LOWS
TONIGHT/SAT NIGHT WITH THE THICKENING LOW CLOUDS AND A BLEND OF
GUIDANCE HIGHS FOR SAT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FCST CONCERNS FOR SUN THRU MON NIGHT...PRECIP TYPES/CHANCES AS
THE TROUGH/LOW DEEPEN AND APPROACH...TEMPERATURES.

19.12Z MODELS SHOW A TIGHTENING CONSENSUS AS STRONG SHORTWAVE ENERGY
TOPS THE WESTERN NOAM RIDGING SUN THEN DROPS INTO THE CENTRAL/
NORTHERN PLAINS SUN NIGHT/MON. THIS CONSENSUS FAVORS SLOWER/
STRONGER OF THE EARLIER RUNS AT 00Z TUE. GOOD AGREEMENT AMONG GFS/
ECMWF/NAM FOR A 500MB LOW NEAR KFSD BY 00Z TUE...MIGRATING TOWARD
KDSM BY 12Z TUE. CAN-GEM MORE PROGRESSIVE/FURTHER NORTH AND
APPEARS AS AN OUTLIER BY MON NIGHT. GIVEN GOOD/TIGHT CONSENSUS
AMONG NAM/ECMWF/ GFS THRU 12Z TUE...FCST CONFIDENCE FOR SUN THRU
MON NIGHT REMAINS GENERALLY GOOD.

FALLING HGTS AND STRENGTHENING LOW PRESSURE IN THE NORTHERN PLAINS
CONTINUES THE SOUTH/SOUTHWEST LOW LEVEL FLOW INTO THE AREA SUN/SUN
NIGHT. SFC THRU 850MB LOW REMAINS NORTHWEST OF THE FCST AREA THRU
00Z TUE. THIS PERSISTENT SOUTH/SOUTHWEST WARM ADVECTION FLOW AHEAD
OF THE LOW WARMS THE SFC-925MB LAYER TO NEAR/ABOVE 0C BY MON/MON
NIGHT. DEPTH OF MOISTURE THE AREA STARTS TO INCREASE SUN ALONG WITH
THE STRENGTH/DEPTH OF THE FORCING/LIFT. MOISTURE/LIFT INCREASE EVEN
MORE FOR SUN NIGHT THRU MON NIGHT WITH PRECIP BECOMING LIKELY FOR
MUCH OF THE AREA MON/MON NIGHT. TRANSITIONED ANY PRECIP FROM -DZ
TO -RA SUN MORNING WITH DEEPER MOISTURE AND ONE STRONGER SURGE OF
850- 700MB WARM ADVECTION LIFTING ACROSS THE AREA. BIT OF A LULL
IN THE LIFT SUN NIGHT WITH THE INCREASE OF DYNAMIC LIFT/PV
ADVECTION AHEAD OF THE TROUGH/SHORTWAVE MOVING ACROSS MON/MON
NIGHT. RAISED PRECIP CHANCES MON INTO MON NIGHT. ADDED PATCHY FOG
FOR SUN NIGHT/MON MORNING AS WELL WITH INCREASING DEW POINTS OVER
THE COLD GROUND. TRENDED PRECIP SUN NIGHT THRU MON NIGHT TOWARD
MORE -RA AS MODEL SOUNDINGS AND X-SECTIONS FOR THIS PERIOD SHOWING
AT LEAST THE SFC- 900MB LAYER WARMING INTO THE 0C TO +3C RANGE...
ESPECIALLY OVER THE CENTRAL/SOUTH PARTS OF THE FCST AREA. LINGERED
A -SN CHANCE MAINLY DURING THE NIGHTTIME/EARLY MORNING HOURS WITH
A COOLER BOUNDARY LAYER AND ANY HEAVIER PRECIP RATES IF THEY OCCUR
CAPABLE OF COOLING THE COLUMN ENOUGH FOR SNOWFLAKES TO REACH THE
GROUND. WILL ALSO HAVE TO WATCH THE LATE NIGHT/EARLY MORNING HOURS
OF SUN/MON NIGHTS FOR -FZRA ON COLD GROUND SURFACES. USED A BLEND
OF THE GUIDANCE HIGHS/ LOWS FOR SUN THRU MON NIGHT...RAISING LOWS
A BIT SUN NIGHT WITH THE SOUTHERLY BOUNDARY LAYER FLOW/THICK LOW
CLOUDS OVER THE AREA.

FOR TUESDAY THRU FRIDAY...DAYS 4 TO 7...

MAIN FORECAST CONCERNS THIS PERIOD...PRECIP CHANCES/TYPES TUE/WED
AND AGAIN FRI...TEMPERATURES.

MEDIUM RANGE MODEL RUNS OF 19.00Z/19.12Z IN QUITE GOOD AGREEMENT TUE
WITH THE TROUGH DEEPENING OVER THE CENTRAL CONUS. TREND FAVORS
SLOWER/STRONGER OF THE EARLIER RUNS. CONSISTENCY REMAINS GOOD FOR
THE TROUGH TO BE PROGRESSIVE INTO THE EASTERN CONUS WED/THU AS
STRONG ENERGY ROTATES UP THE EAST SIDE OF THE TROUGH. IMPROVING
SIGNAL FOR SHORTWAVE RIDGING TO BUILD OVER THE MID/UPPER MS VALLEY
FOR CHRISTMAS DAY...AS ONE TROUGH LIFTS INTO THE CAN MARITIMES AND
MORE ENERGY DIGS INTO THE CENTRAL/SOUTHERN ROCKIES. POTENTIAL FOR
SOME PORTION OF THE ENERGY TO LIFT TOWARD/INTO THE MID/UPPER MS
VALLEY FRI. PLENTY OF SPREAD AMONG THE MODELS AND ENSEMBLE
MEMBERS WITH THE DETAILS BY DAY 7. CONFIDENCE IN THE DAY 4-7
PERIOD IS AVERAGE TO GOOD TUE-THU THEN AVERAGE TO BELOW FOR FRI.

IMPROVING MODEL CONSENSUS FOR THE SFC-700MB LOW TO BE OCCLUDING/
AS IT MOVES ACROSS THE UPPER MIDWEST TUE. FORCING/LIFT OVER THE
FCST AREA WEAKENS THRU TUE/TUE NIGHT WITH THE MOISTURE CONVEYOR
BEING PUSHED FURTHER FROM THE AREA BY THE OCCLUSION. COLUMN DOES
COOL TUE AS THE OCCLUDING LOW/MID LEVEL TROUGH AXIS PASS. HIGHER
CHANCES OF PRECIP TUE/TUE NIGHT AS A DEFORMATION BAND WOULD
ROTATE ACROSS THE AREA. MIX OF -RA/-SN TUE MORNING GIVING WAY TO
-SN FOR LATE TUE/TUE NIGHT. STRONG ENERGY IN THE SOUTHERN PORTION
OF THE LONGWAVE TROUGH ROTATING UP THE EASTERN SEABOARD WED DRAGS
THE MID LEVEL LOW INTO THE EASTERN GREAT LAKES BY WED NIGHT...
SPREADING DRYING NORTHWEST 850-500MB FLOW OVER THE REGION. ANY
LINGERING -SN LOOKING TO TAPER OFF FROM SOUTHWEST TO NORTHEAST
WED/WED EVENING. SFC THRU MID LEVEL RIDGING PROGGED TO SLIDE
ACROSS THE UPPER MIDWEST THU...WITH OUR BEST SHOT AT SOME SUNSHINE
NEXT WEEK ON CHRISTMAS DAY. CONFIDENCE AVERAGE AT BEST FRI BUT
LATEST DETERMINISTIC MODEL RUNS WOULD LIFT A PORTION OF THE
ROCKIES ENERGY INTO THE UPPER MIDWEST AT THE END OF THE WEEK.
PLENTY OF LOWER LEVEL DETAIL DIFFERENCES BY FRI WITH ANY
POTENTIAL SFC LOW TRACK/STRENGTH AND HOW MUCH WARM AIR IS DRAWN
NORTH AHEAD OF THE SYSTEM FOR PRECIP TYPE ISSUES. WILL STAY WITH
THE MODEL/ENSEMBLE CONSENSUS ON FRI FOR NOW. MODEL/ENSEMBLE
CONSENSUS OF HIGHS/LOWS FOR TUE-FRI SEEMS TO HAVE THEM WELL
TRENDED AS WELL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM CST FRI DEC 19 2014

CEILINGS HAVE STAYED UP A LITTLE HIGHER THAN EXPECTED THIS
EVENING...WHICH MIGHT BE A FUNCTION OF NOT BEING IN THE HIGHER
MOISTURE RETURN TAKING PLACE ALONG AND WEST OF I-35. A SOUTH TO
SOUTHEAST WIND TO THIS POINT HAS HELPED KEEP LOW CEILINGS OFF TO
THE WEST. HOWEVER...JUST ABOVE THE GROUND THE WINDS ARE FORECAST
TO TURN MORE TO THE SOUTHWEST OVER THE NEXT FEW HOURS. AS A
RESULT...ANTICIPATING RST TO LOWER FROM MVFR TO IFR BY 10Z...ALONG
WITH THE FORMATION OF SOME MVFR BR. AT LSE...CONDITIONS WILL STAY
MVFR...BUT CEILINGS SHOULD DROP SOME. TOWARDS THE MIDDLE OF THE
DAY...DAYTIME HEATING PLUS THE FLOW JUST ABOVE THE GROUND BACKING
MORE SOUTHERLY SHOULD ALLOW CEILINGS TO COME UP SOME...AT LEAST
ENOUGH TO PULL RST OUT OF IFR. THE FLOW STAYS CONSISTENT INTO THE
EVENING...THUS HELD CEILINGS STEADY. ITS POSSIBLE RST FALLS TO
IFR LATE IN THE EVENING...BUT CONFIDENCE IS TOO LOW TO INCLUDE AT
THIS TIME.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ




000
FXUS63 KARX 192310
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
510 PM CST FRI DEC 19 2014

.SHORT TERM...(TONIGHT THRU SATURDAY NIGHT)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FORECAST CONCERNS THIS PERIOD...LOW LEVEL MOISTURE/CLOUDS AND
ANY -FZDZ CHANCES...TEMPERATURES.

18Z DATA ANALYSIS HAD A BROAD AREA OF HIGH PRESSURE FROM EASTERN ONT
SOUTHWEST TO MO. 19.12Z RAOBS SHOWED A RATHER STRONG INVERSION NEAR
900MB ACROSS THE REGION...WITH PLENTY OF MOISTURE TRAPPED IN/UNDER
IT PRODUCING RATHER WIDESPREAD LOWER STRATUS CLOUDS ACROSS THE
REGION. SOME BREAKS IN THE CLOUDS OVER PARTS OF IL/EASTERN WI.
OTHERWISE DEVELOPING SOUTHEAST TO SOUTH FLOW ON THE WEST SIDE OF THE
RIDGE AXIS WAS ADVECTING MORE MOISTURE NORTHWARD INTO IA/MN. WITH
LACK OF SNOW COVER...TEMPS ACTUALLY WARMING A BIT TODAY UNDER THE
CLOUDS IN THE DEVELOPING SOUTHERLY WARM ADVECTION FLOW.

19.12Z MODELS LOOK TO HAVE INITIALIZED WELL...THOUGH ALL WERE ABOUT
1MB TOO HIGH WITH SFC PRESSURES IN THE BROAD HIGH FROM ONT TO THE
MID MS VALLEY. SOLUTIONS SIMILAR FOR TONIGHT THRU SAT NIGHT AND
CONVERGING TOWARD A TIGHTER COMPROMISE OF THEIR EARLIER RUNS AS
ONE SHORTWAVE PASSES SOUTH OF THE AREA TONIGHT AND ANOTHER MOVES
INTO MN SAT NIGHT. SHORT-TERM FCST CONFIDENCE IS GENERALLY GOOD
THIS CYCLE.

IN THE SHORT TERM...THE MAIN CONCERN TONIGHT THRU SAT NIGHT IS THE
DEPTH OF THE LOWER LEVEL MOISTURE/STRATUS AND EXTENT OF ANY LIFT
IN/JUST ABOVE THE MOISTURE LAYER. THIS MOISTURE REMAINS TRAPPED
UNDER AN INVERSION AROUND 850MB TONIGHT AND AROUND 900MB SAT NIGHT.
DEEPEST MOISTURE IS OVER THE FCST AREA LATE THIS AFTERNOON/EVENING
BUT MOST CLOUD BASES IN THE 1500-2500 FT RANGE WITH SFC TEMP-DEW
POINT SPREADS OF 5F TO 10F. THIS NOT OVERLY CONDUCIVE TO TO -DZ/
-FZDZ AND REMOVED ANY -FZDZ MENTION THRU THIS EVENING. WEAK/MDT
925MB WARM ADVECTION AND 280-285K PERSIST ACROSS THE AREA TONIGHT
THRU SAT NIGHT. SOME OF THE STRONGER OF THIS SAT NIGHT AS THE 925MB
FLOW INCREASE TO AROUND 20KTS. SFC-925MB SATURATION INCREASES THRU
TONIGHT...WITH LOWERING CIGS AND TEMP-DEW POINT SPREADS. WILL
CONTINUE THE PATCHY -FZDZ SPREADING ACROSS MUCH OF THE FCST AREA
DURING THE LATE EVENING/OVERNIGHT HOURS INTO EARLY SAT MORNING.
ADDED A PATCHY FOG MENTION OVERNIGHT INTO SAT MORNING AS WELL. LEFT
THE BULK OF SAT/SAT EVENING DRY BUT CANNOT RULE OUT ISOLATED -DZ/
-FZDZ AND PATCHY FOG. CONTINUED THE PATCHY -FZDZ MENTION LATER SAT
NIGHT WITH THE INCREASE OF LIFT LATE BUT DID REMOVE ANY -SN MENTION
AS TOP OF THE MOISTURE COLUMN LATER SAT NIGHT WOULD ONLY BE ABOUT
-5C AT THE COLDEST WITH NO ICE IN THE CLOUDS. ADDED SOME FOG FOR
THIS PERIOD AS AN INCREASINGLY MOIST SFC-925MB AIRMASS IS PUSHED
NORTHWARD OVER THE COLD LANDSCAPE. FAVORED WARMER OF GUIDANCE LOWS
TONIGHT/SAT NIGHT WITH THE THICKENING LOW CLOUDS AND A BLEND OF
GUIDANCE HIGHS FOR SAT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FCST CONCERNS FOR SUN THRU MON NIGHT...PRECIP TYPES/CHANCES AS
THE TROUGH/LOW DEEPEN AND APPROACH...TEMPERATURES.

19.12Z MODELS SHOW A TIGHTENING CONSENSUS AS STRONG SHORTWAVE ENERGY
TOPS THE WESTERN NOAM RIDGING SUN THEN DROPS INTO THE CENTRAL/
NORTHERN PLAINS SUN NIGHT/MON. THIS CONSENSUS FAVORS SLOWER/
STRONGER OF THE EARLIER RUNS AT 00Z TUE. GOOD AGREEMENT AMONG GFS/
ECMWF/NAM FOR A 500MB LOW NEAR KFSD BY 00Z TUE...MIGRATING TOWARD
KDSM BY 12Z TUE. CAN-GEM MORE PROGRESSIVE/FURTHER NORTH AND
APPEARS AS AN OUTLIER BY MON NIGHT. GIVEN GOOD/TIGHT CONSENSUS
AMONG NAM/ECMWF/ GFS THRU 12Z TUE...FCST CONFIDENCE FOR SUN THRU
MON NIGHT REMAINS GENERALLY GOOD.

FALLING HGTS AND STRENGTHENING LOW PRESSURE IN THE NORTHERN PLAINS
CONTINUES THE SOUTH/SOUTHWEST LOW LEVEL FLOW INTO THE AREA SUN/SUN
NIGHT. SFC THRU 850MB LOW REMAINS NORTHWEST OF THE FCST AREA THRU
00Z TUE. THIS PERSISTENT SOUTH/SOUTHWEST WARM ADVECTION FLOW AHEAD
OF THE LOW WARMS THE SFC-925MB LAYER TO NEAR/ABOVE 0C BY MON/MON
NIGHT. DEPTH OF MOISTURE THE AREA STARTS TO INCREASE SUN ALONG WITH
THE STRENGTH/DEPTH OF THE FORCING/LIFT. MOISTURE/LIFT INCREASE EVEN
MORE FOR SUN NIGHT THRU MON NIGHT WITH PRECIP BECOMING LIKELY FOR
MUCH OF THE AREA MON/MON NIGHT. TRANSITIONED ANY PRECIP FROM -DZ
TO -RA SUN MORNING WITH DEEPER MOISTURE AND ONE STRONGER SURGE OF
850- 700MB WARM ADVECTION LIFTING ACROSS THE AREA. BIT OF A LULL
IN THE LIFT SUN NIGHT WITH THE INCREASE OF DYNAMIC LIFT/PV
ADVECTION AHEAD OF THE TROUGH/SHORTWAVE MOVING ACROSS MON/MON
NIGHT. RAISED PRECIP CHANCES MON INTO MON NIGHT. ADDED PATCHY FOG
FOR SUN NIGHT/MON MORNING AS WELL WITH INCREASING DEW POINTS OVER
THE COLD GROUND. TRENDED PRECIP SUN NIGHT THRU MON NIGHT TOWARD
MORE -RA AS MODEL SOUNDINGS AND X-SECTIONS FOR THIS PERIOD SHOWING
AT LEAST THE SFC- 900MB LAYER WARMING INTO THE 0C TO +3C RANGE...
ESPECIALLY OVER THE CENTRAL/SOUTH PARTS OF THE FCST AREA. LINGERED
A -SN CHANCE MAINLY DURING THE NIGHTTIME/EARLY MORNING HOURS WITH
A COOLER BOUNDARY LAYER AND ANY HEAVIER PRECIP RATES IF THEY OCCUR
CAPABLE OF COOLING THE COLUMN ENOUGH FOR SNOWFLAKES TO REACH THE
GROUND. WILL ALSO HAVE TO WATCH THE LATE NIGHT/EARLY MORNING HOURS
OF SUN/MON NIGHTS FOR -FZRA ON COLD GROUND SURFACES. USED A BLEND
OF THE GUIDANCE HIGHS/ LOWS FOR SUN THRU MON NIGHT...RAISING LOWS
A BIT SUN NIGHT WITH THE SOUTHERLY BOUNDARY LAYER FLOW/THICK LOW
CLOUDS OVER THE AREA.

FOR TUESDAY THRU FRIDAY...DAYS 4 TO 7...

MAIN FORECAST CONCERNS THIS PERIOD...PRECIP CHANCES/TYPES TUE/WED
AND AGAIN FRI...TEMPERATURES.

MEDIUM RANGE MODEL RUNS OF 19.00Z/19.12Z IN QUITE GOOD AGREEMENT TUE
WITH THE TROUGH DEEPENING OVER THE CENTRAL CONUS. TREND FAVORS
SLOWER/STRONGER OF THE EARLIER RUNS. CONSISTENCY REMAINS GOOD FOR
THE TROUGH TO BE PROGRESSIVE INTO THE EASTERN CONUS WED/THU AS
STRONG ENERGY ROTATES UP THE EAST SIDE OF THE TROUGH. IMPROVING
SIGNAL FOR SHORTWAVE RIDGING TO BUILD OVER THE MID/UPPER MS VALLEY
FOR CHRISTMAS DAY...AS ONE TROUGH LIFTS INTO THE CAN MARITIMES AND
MORE ENERGY DIGS INTO THE CENTRAL/SOUTHERN ROCKIES. POTENTIAL FOR
SOME PORTION OF THE ENERGY TO LIFT TOWARD/INTO THE MID/UPPER MS
VALLEY FRI. PLENTY OF SPREAD AMONG THE MODELS AND ENSEMBLE
MEMBERS WITH THE DETAILS BY DAY 7. CONFIDENCE IN THE DAY 4-7
PERIOD IS AVERAGE TO GOOD TUE-THU THEN AVERAGE TO BELOW FOR FRI.

IMPROVING MODEL CONSENSUS FOR THE SFC-700MB LOW TO BE OCCLUDING/
AS IT MOVES ACROSS THE UPPER MIDWEST TUE. FORCING/LIFT OVER THE
FCST AREA WEAKENS THRU TUE/TUE NIGHT WITH THE MOISTURE CONVEYOR
BEING PUSHED FURTHER FROM THE AREA BY THE OCCLUSION. COLUMN DOES
COOL TUE AS THE OCCLUDING LOW/MID LEVEL TROUGH AXIS PASS. HIGHER
CHANCES OF PRECIP TUE/TUE NIGHT AS A DEFORMATION BAND WOULD
ROTATE ACROSS THE AREA. MIX OF -RA/-SN TUE MORNING GIVING WAY TO
-SN FOR LATE TUE/TUE NIGHT. STRONG ENERGY IN THE SOUTHERN PORTION
OF THE LONGWAVE TROUGH ROTATING UP THE EASTERN SEABOARD WED DRAGS
THE MID LEVEL LOW INTO THE EASTERN GREAT LAKES BY WED NIGHT...
SPREADING DRYING NORTHWEST 850-500MB FLOW OVER THE REGION. ANY
LINGERING -SN LOOKING TO TAPER OFF FROM SOUTHWEST TO NORTHEAST
WED/WED EVENING. SFC THRU MID LEVEL RIDGING PROGGED TO SLIDE
ACROSS THE UPPER MIDWEST THU...WITH OUR BEST SHOT AT SOME SUNSHINE
NEXT WEEK ON CHRISTMAS DAY. CONFIDENCE AVERAGE AT BEST FRI BUT
LATEST DETERMINISTIC MODEL RUNS WOULD LIFT A PORTION OF THE
ROCKIES ENERGY INTO THE UPPER MIDWEST AT THE END OF THE WEEK.
PLENTY OF LOWER LEVEL DETAIL DIFFERENCES BY FRI WITH ANY
POTENTIAL SFC LOW TRACK/STRENGTH AND HOW MUCH WARM AIR IS DRAWN
NORTH AHEAD OF THE SYSTEM FOR PRECIP TYPE ISSUES. WILL STAY WITH
THE MODEL/ENSEMBLE CONSENSUS ON FRI FOR NOW. MODEL/ENSEMBLE
CONSENSUS OF HIGHS/LOWS FOR TUE-FRI SEEMS TO HAVE THEM WELL
TRENDED AS WELL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 510 PM CST FRI DEC 19 2014

A 5-10KT SOUTHERLY FLOW IS FORECAST TO PERSIST AT THE TAF SITES
THROUGH SATURDAY...WHICH EVER SO SLOWLY WILL BRING IN MORE
MOISTURE. EXPECT THIS MOISTURE TO MANIFEST AS A PERSISTENT STRATUS
DECK...WITH CEILINGS MAINLY MVFR AT LSE AND MVFR/IFR AT RST. THE
BEST CHANCE FOR IFR AT RST AS WELL AS MVFR BR IS FROM LATE THIS
EVENING INTO SATURDAY MORNING...COINCIDING WITH THE DIURNAL
MINIMUM. ADDITIONALLY...IFR CEILINGS AND MVFR VISIBILITIES ARE NOT
FAR AWAY FROM RST...NEAR I-35.

CANNOT RULE OUT SOME PATCHY FREEZING DRIZZLE AT RST...BUT
CONFIDENCE IS TOO LOW TO INCLUDE AT THIS TIME.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION...AJ





000
FXUS63 KARX 192100
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
300 PM CST FRI DEC 19 2014

.SHORT TERM...(TONIGHT THRU SATURDAY NIGHT)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FORECAST CONCERNS THIS PERIOD...LOW LEVEL MOISTURE/CLOUDS AND
ANY -FZDZ CHANCES...TEMPERATURES.

18Z DATA ANALYSIS HAD A BROAD AREA OF HIGH PRESSURE FROM EASTERN ONT
SOUTHWEST TO MO. 19.12Z RAOBS SHOWED A RATHER STRONG INVERSION NEAR
900MB ACROSS THE REGION...WITH PLENTY OF MOISTURE TRAPPED IN/UNDER
IT PRODUCING RATHER WIDESPREAD LOWER STRATUS CLOUDS ACROSS THE
REGION. SOME BREAKS IN THE CLOUDS OVER PARTS OF IL/EASTERN WI.
OTHERWISE DEVELOPING SOUTHEAST TO SOUTH FLOW ON THE WEST SIDE OF THE
RIDGE AXIS WAS ADVECTING MORE MOISTURE NORTHWARD INTO IA/MN. WITH
LACK OF SNOW COVER...TEMPS ACTUALLY WARMING A BIT TODAY UNDER THE
CLOUDS IN THE DEVELOPING SOUTHERLY WARM ADVECTION FLOW.

19.12Z MODELS LOOK TO HAVE INITIALIZED WELL...THOUGH ALL WERE ABOUT
1MB TOO HIGH WITH SFC PRESSURES IN THE BROAD HIGH FROM ONT TO THE
MID MS VALLEY. SOLUTIONS SIMILAR FOR TONIGHT THRU SAT NIGHT AND
CONVERGING TOWARD A TIGHTER COMPROMISE OF THEIR EARLIER RUNS AS
ONE SHORTWAVE PASSES SOUTH OF THE AREA TONIGHT AND ANOTHER MOVES
INTO MN SAT NIGHT. SHORT-TERM FCST CONFIDENCE IS GENERALLY GOOD
THIS CYCLE.

IN THE SHORT TERM...THE MAIN CONCERN TONIGHT THRU SAT NIGHT IS THE
DEPTH OF THE LOWER LEVEL MOISTURE/STRATUS AND EXTENT OF ANY LIFT
IN/JUST ABOVE THE MOISTURE LAYER. THIS MOISTURE REMAINS TRAPPED
UNDER AN INVERSION AROUND 850MB TONIGHT AND AROUND 900MB SAT NIGHT.
DEEPEST MOISTURE IS OVER THE FCST AREA LATE THIS AFTERNOON/EVENING
BUT MOST CLOUD BASES IN THE 1500-2500 FT RANGE WITH SFC TEMP-DEW
POINT SPREADS OF 5F TO 10F. THIS NOT OVERLY CONDUCIVE TO TO -DZ/
-FZDZ AND REMOVED ANY -FZDZ MENTION THRU THIS EVENING. WEAK/MDT
925MB WARM ADVECTION AND 280-285K PERSIST ACROSS THE AREA TONIGHT
THRU SAT NIGHT. SOME OF THE STRONGER OF THIS SAT NIGHT AS THE 925MB
FLOW INCREASE TO AROUND 20KTS. SFC-925MB SATURATION INCREASES THRU
TONIGHT...WITH LOWERING CIGS AND TEMP-DEW POINT SPREADS. WILL
CONTINUE THE PATCHY -FZDZ SPREADING ACROSS MUCH OF THE FCST AREA
DURING THE LATE EVENING/OVERNIGHT HOURS INTO EARLY SAT MORNING.
ADDED A PATCHY FOG MENTION OVERNIGHT INTO SAT MORNING AS WELL. LEFT
THE BULK OF SAT/SAT EVENING DRY BUT CANNOT RULE OUT ISOLATED -DZ/
-FZDZ AND PATCHY FOG. CONTINUED THE PATCHY -FZDZ MENTION LATER SAT
NIGHT WITH THE INCREASE OF LIFT LATE BUT DID REMOVE ANY -SN MENTION
AS TOP OF THE MOISTURE COLUMN LATER SAT NIGHT WOULD ONLY BE ABOUT
-5C AT THE COLDEST WITH NO ICE IN THE CLOUDS. ADDED SOME FOG FOR
THIS PERIOD AS AN INCREASINGLY MOIST SFC-925MB AIRMASS IS PUSHED
NORTHWARD OVER THE COLD LANDSCAPE. FAVORED WARMER OF GUIDANCE LOWS
TONIGHT/SAT NIGHT WITH THE THICKENING LOW CLOUDS AND A BLEND OF
GUIDANCE HIGHS FOR SAT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FCST CONCERNS FOR SUN THRU MON NIGHT...PRECIP TYPES/CHANCES AS
THE TROUGH/LOW DEEPEN AND APPROACH...TEMPERATURES.

19.12Z MODELS SHOW A TIGHTENING CONSENSUS AS STRONG SHORTWAVE ENERGY
TOPS THE WESTERN NOAM RIDGING SUN THEN DROPS INTO THE CENTRAL/
NORTHERN PLAINS SUN NIGHT/MON. THIS CONSENSUS FAVORS SLOWER/
STRONGER OF THE EARLIER RUNS AT 00Z TUE. GOOD AGREEMENT AMONG GFS/
ECMWF/NAM FOR A 500MB LOW NEAR KFSD BY 00Z TUE...MIGRATING TOWARD
KDSM BY 12Z TUE. CAN-GEM MORE PROGRESSIVE/FURTHER NORTH AND
APPEARS AS AN OUTLIER BY MON NIGHT. GIVEN GOOD/TIGHT CONSENSUS
AMONG NAM/ECMWF/ GFS THRU 12Z TUE...FCST CONFIDENCE FOR SUN THRU
MON NIGHT REMAINS GENERALLY GOOD.

FALLING HGTS AND STRENGTHENING LOW PRESSURE IN THE NORTHERN PLAINS
CONTINUES THE SOUTH/SOUTHWEST LOW LEVEL FLOW INTO THE AREA SUN/SUN
NIGHT. SFC THRU 850MB LOW REMAINS NORTHWEST OF THE FCST AREA THRU
00Z TUE. THIS PERSISTENT SOUTH/SOUTHWEST WARM ADVECTION FLOW AHEAD
OF THE LOW WARMS THE SFC-925MB LAYER TO NEAR/ABOVE 0C BY MON/MON
NIGHT. DEPTH OF MOISTURE THE AREA STARTS TO INCREASE SUN ALONG WITH
THE STRENGTH/DEPTH OF THE FORCING/LIFT. MOISTURE/LIFT INCREASE EVEN
MORE FOR SUN NIGHT THRU MON NIGHT WITH PRECIP BECOMING LIKELY FOR
MUCH OF THE AREA MON/MON NIGHT. TRANSITIONED ANY PRECIP FROM -DZ
TO -RA SUN MORNING WITH DEEPER MOISTURE AND ONE STRONGER SURGE OF
850- 700MB WARM ADVECTION LIFTING ACROSS THE AREA. BIT OF A LULL
IN THE LIFT SUN NIGHT WITH THE INCREASE OF DYNAMIC LIFT/PV
ADVECTION AHEAD OF THE TROUGH/SHORTWAVE MOVING ACROSS MON/MON
NIGHT. RAISED PRECIP CHANCES MON INTO MON NIGHT. ADDED PATCHY FOG
FOR SUN NIGHT/MON MORNING AS WELL WITH INCREASING DEW POINTS OVER
THE COLD GROUND. TRENDED PRECIP SUN NIGHT THRU MON NIGHT TOWARD
MORE -RA AS MODEL SOUNDINGS AND X-SECTIONS FOR THIS PERIOD SHOWING
AT LEAST THE SFC- 900MB LAYER WARMING INTO THE 0C TO +3C RANGE...
ESPECIALLY OVER THE CENTRAL/SOUTH PARTS OF THE FCST AREA. LINGERED
A -SN CHANCE MAINLY DURING THE NIGHTTIME/EARLY MORNING HOURS WITH
A COOLER BOUNDARY LAYER AND ANY HEAVIER PRECIP RATES IF THEY OCCUR
CAPABLE OF COOLING THE COLUMN ENOUGH FOR SNOWFLAKES TO REACH THE
GROUND. WILL ALSO HAVE TO WATCH THE LATE NIGHT/EARLY MORNING HOURS
OF SUN/MON NIGHTS FOR -FZRA ON COLD GROUND SURFACES. USED A BLEND
OF THE GUIDANCE HIGHS/ LOWS FOR SUN THRU MON NIGHT...RAISING LOWS
A BIT SUN NIGHT WITH THE SOUTHERLY BOUNDARY LAYER FLOW/THICK LOW
CLOUDS OVER THE AREA.

FOR TUESDAY THRU FRIDAY...DAYS 4 TO 7...

MAIN FORECAST CONCERNS THIS PERIOD...PRECIP CHANCES/TYPES TUE/WED
AND AGAIN FRI...TEMPERATURES.

MEDIUM RANGE MODEL RUNS OF 19.00Z/19.12Z IN QUITE GOOD AGREEMENT TUE
WITH THE TROUGH DEEPENING OVER THE CENTRAL CONUS. TREND FAVORS
SLOWER/STRONGER OF THE EARLIER RUNS. CONSISTENCY REMAINS GOOD FOR
THE TROUGH TO BE PROGRESSIVE INTO THE EASTERN CONUS WED/THU AS
STRONG ENERGY ROTATES UP THE EAST SIDE OF THE TROUGH. IMPROVING
SIGNAL FOR SHORTWAVE RIDGING TO BUILD OVER THE MID/UPPER MS VALLEY
FOR CHRISTMAS DAY...AS ONE TROUGH LIFTS INTO THE CAN MARITIMES AND
MORE ENERGY DIGS INTO THE CENTRAL/SOUTHERN ROCKIES. POTENTIAL FOR
SOME PORTION OF THE ENERGY TO LIFT TOWARD/INTO THE MID/UPPER MS
VALLEY FRI. PLENTY OF SPREAD AMONG THE MODELS AND ENSEMBLE
MEMBERS WITH THE DETAILS BY DAY 7. CONFIDENCE IN THE DAY 4-7
PERIOD IS AVERAGE TO GOOD TUE-THU THEN AVERAGE TO BELOW FOR FRI.

IMPROVING MODEL CONSENSUS FOR THE SFC-700MB LOW TO BE OCCLUDING/
AS IT MOVES ACROSS THE UPPER MIDWEST TUE. FORCING/LIFT OVER THE
FCST AREA WEAKENS THRU TUE/TUE NIGHT WITH THE MOISTURE CONVEYOR
BEING PUSHED FURTHER FROM THE AREA BY THE OCCLUSION. COLUMN DOES
COOL TUE AS THE OCCLUDING LOW/MID LEVEL TROUGH AXIS PASS. HIGHER
CHANCES OF PRECIP TUE/TUE NIGHT AS A DEFORMATION BAND WOULD
ROTATE ACROSS THE AREA. MIX OF -RA/-SN TUE MORNING GIVING WAY TO
-SN FOR LATE TUE/TUE NIGHT. STRONG ENERGY IN THE SOUTHERN PORTION
OF THE LONGWAVE TROUGH ROTATING UP THE EASTERN SEABOARD WED DRAGS
THE MID LEVEL LOW INTO THE EASTERN GREAT LAKES BY WED NIGHT...
SPREADING DRYING NORTHWEST 850-500MB FLOW OVER THE REGION. ANY
LINGERING -SN LOOKING TO TAPER OFF FROM SOUTHWEST TO NORTHEAST
WED/WED EVENING. SFC THRU MID LEVEL RIDGING PROGGED TO SLIDE
ACROSS THE UPPER MIDWEST THU...WITH OUR BEST SHOT AT SOME SUNSHINE
NEXT WEEK ON CHRISTMAS DAY. CONFIDENCE AVERAGE AT BEST FRI BUT
LATEST DETERMINISTIC MODEL RUNS WOULD LIFT A PORTION OF THE
ROCKIES ENERGY INTO THE UPPER MIDWEST AT THE END OF THE WEEK.
PLENTY OF LOWER LEVEL DETAIL DIFFERENCES BY FRI WITH ANY
POTENTIAL SFC LOW TRACK/STRENGTH AND HOW MUCH WARM AIR IS DRAWN
NORTH AHEAD OF THE SYSTEM FOR PRECIP TYPE ISSUES. WILL STAY WITH
THE MODEL/ENSEMBLE CONSENSUS ON FRI FOR NOW. MODEL/ENSEMBLE
CONSENSUS OF HIGHS/LOWS FOR TUE-FRI SEEMS TO HAVE THEM WELL
TRENDED AS WELL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1133 AM CST FRI DEC 19 2014

IFR CEILINGS/MVFR VISIBILITY IN MIST IS STAYING JUST WEST OF
KRST/KLSE ACROSS MUCH OF CENTRAL MN/IA LATE THIS MORNING. LATEST
FORECAST GUIDANCE SUGGESTS THESE LOW CLOUDS WILL SLOWLY PUSH EAST
THROUGH THE PERIOD...BUT WITH A PREDOMINANT SOUTH WIND...DELAYED
ONSET OF LOWER CEILINGS AT KRST UNTIL 19.22Z AND AT KLSE UNTIL
20.03Z. PATCHY FREEZING DRIZZLE POSSIBLE OVERNIGHT...BUT COVERAGE
UNCERTAINTY PRECLUDES MENTION IN 19.18Z TAFS. WILL NEED TO WATCH
FOR A FURTHER LOWERING OF CEILINGS/VISIBILITY IN THE HOURS AROUND
DAYBREAK SATURDAY MORNING. OTHERWISE...CONDITIONS SHOULD REBOUND
SLIGHTLY NEAR THE END OF THE PERIOD. SOUTHERLY WINDS WILL
CONTINUE...GENERALLY 10 KTS OR LESS.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....ROGERS




000
FXUS63 KARX 192100
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
300 PM CST FRI DEC 19 2014

.SHORT TERM...(TONIGHT THRU SATURDAY NIGHT)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FORECAST CONCERNS THIS PERIOD...LOW LEVEL MOISTURE/CLOUDS AND
ANY -FZDZ CHANCES...TEMPERATURES.

18Z DATA ANALYSIS HAD A BROAD AREA OF HIGH PRESSURE FROM EASTERN ONT
SOUTHWEST TO MO. 19.12Z RAOBS SHOWED A RATHER STRONG INVERSION NEAR
900MB ACROSS THE REGION...WITH PLENTY OF MOISTURE TRAPPED IN/UNDER
IT PRODUCING RATHER WIDESPREAD LOWER STRATUS CLOUDS ACROSS THE
REGION. SOME BREAKS IN THE CLOUDS OVER PARTS OF IL/EASTERN WI.
OTHERWISE DEVELOPING SOUTHEAST TO SOUTH FLOW ON THE WEST SIDE OF THE
RIDGE AXIS WAS ADVECTING MORE MOISTURE NORTHWARD INTO IA/MN. WITH
LACK OF SNOW COVER...TEMPS ACTUALLY WARMING A BIT TODAY UNDER THE
CLOUDS IN THE DEVELOPING SOUTHERLY WARM ADVECTION FLOW.

19.12Z MODELS LOOK TO HAVE INITIALIZED WELL...THOUGH ALL WERE ABOUT
1MB TOO HIGH WITH SFC PRESSURES IN THE BROAD HIGH FROM ONT TO THE
MID MS VALLEY. SOLUTIONS SIMILAR FOR TONIGHT THRU SAT NIGHT AND
CONVERGING TOWARD A TIGHTER COMPROMISE OF THEIR EARLIER RUNS AS
ONE SHORTWAVE PASSES SOUTH OF THE AREA TONIGHT AND ANOTHER MOVES
INTO MN SAT NIGHT. SHORT-TERM FCST CONFIDENCE IS GENERALLY GOOD
THIS CYCLE.

IN THE SHORT TERM...THE MAIN CONCERN TONIGHT THRU SAT NIGHT IS THE
DEPTH OF THE LOWER LEVEL MOISTURE/STRATUS AND EXTENT OF ANY LIFT
IN/JUST ABOVE THE MOISTURE LAYER. THIS MOISTURE REMAINS TRAPPED
UNDER AN INVERSION AROUND 850MB TONIGHT AND AROUND 900MB SAT NIGHT.
DEEPEST MOISTURE IS OVER THE FCST AREA LATE THIS AFTERNOON/EVENING
BUT MOST CLOUD BASES IN THE 1500-2500 FT RANGE WITH SFC TEMP-DEW
POINT SPREADS OF 5F TO 10F. THIS NOT OVERLY CONDUCIVE TO TO -DZ/
-FZDZ AND REMOVED ANY -FZDZ MENTION THRU THIS EVENING. WEAK/MDT
925MB WARM ADVECTION AND 280-285K PERSIST ACROSS THE AREA TONIGHT
THRU SAT NIGHT. SOME OF THE STRONGER OF THIS SAT NIGHT AS THE 925MB
FLOW INCREASE TO AROUND 20KTS. SFC-925MB SATURATION INCREASES THRU
TONIGHT...WITH LOWERING CIGS AND TEMP-DEW POINT SPREADS. WILL
CONTINUE THE PATCHY -FZDZ SPREADING ACROSS MUCH OF THE FCST AREA
DURING THE LATE EVENING/OVERNIGHT HOURS INTO EARLY SAT MORNING.
ADDED A PATCHY FOG MENTION OVERNIGHT INTO SAT MORNING AS WELL. LEFT
THE BULK OF SAT/SAT EVENING DRY BUT CANNOT RULE OUT ISOLATED -DZ/
-FZDZ AND PATCHY FOG. CONTINUED THE PATCHY -FZDZ MENTION LATER SAT
NIGHT WITH THE INCREASE OF LIFT LATE BUT DID REMOVE ANY -SN MENTION
AS TOP OF THE MOISTURE COLUMN LATER SAT NIGHT WOULD ONLY BE ABOUT
-5C AT THE COLDEST WITH NO ICE IN THE CLOUDS. ADDED SOME FOG FOR
THIS PERIOD AS AN INCREASINGLY MOIST SFC-925MB AIRMASS IS PUSHED
NORTHWARD OVER THE COLD LANDSCAPE. FAVORED WARMER OF GUIDANCE LOWS
TONIGHT/SAT NIGHT WITH THE THICKENING LOW CLOUDS AND A BLEND OF
GUIDANCE HIGHS FOR SAT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 PM CST FRI DEC 19 2014

MAIN FCST CONCERNS FOR SUN THRU MON NIGHT...PRECIP TYPES/CHANCES AS
THE TROUGH/LOW DEEPEN AND APPROACH...TEMPERATURES.

19.12Z MODELS SHOW A TIGHTENING CONSENSUS AS STRONG SHORTWAVE ENERGY
TOPS THE WESTERN NOAM RIDGING SUN THEN DROPS INTO THE CENTRAL/
NORTHERN PLAINS SUN NIGHT/MON. THIS CONSENSUS FAVORS SLOWER/
STRONGER OF THE EARLIER RUNS AT 00Z TUE. GOOD AGREEMENT AMONG GFS/
ECMWF/NAM FOR A 500MB LOW NEAR KFSD BY 00Z TUE...MIGRATING TOWARD
KDSM BY 12Z TUE. CAN-GEM MORE PROGRESSIVE/FURTHER NORTH AND
APPEARS AS AN OUTLIER BY MON NIGHT. GIVEN GOOD/TIGHT CONSENSUS
AMONG NAM/ECMWF/ GFS THRU 12Z TUE...FCST CONFIDENCE FOR SUN THRU
MON NIGHT REMAINS GENERALLY GOOD.

FALLING HGTS AND STRENGTHENING LOW PRESSURE IN THE NORTHERN PLAINS
CONTINUES THE SOUTH/SOUTHWEST LOW LEVEL FLOW INTO THE AREA SUN/SUN
NIGHT. SFC THRU 850MB LOW REMAINS NORTHWEST OF THE FCST AREA THRU
00Z TUE. THIS PERSISTENT SOUTH/SOUTHWEST WARM ADVECTION FLOW AHEAD
OF THE LOW WARMS THE SFC-925MB LAYER TO NEAR/ABOVE 0C BY MON/MON
NIGHT. DEPTH OF MOISTURE THE AREA STARTS TO INCREASE SUN ALONG WITH
THE STRENGTH/DEPTH OF THE FORCING/LIFT. MOISTURE/LIFT INCREASE EVEN
MORE FOR SUN NIGHT THRU MON NIGHT WITH PRECIP BECOMING LIKELY FOR
MUCH OF THE AREA MON/MON NIGHT. TRANSITIONED ANY PRECIP FROM -DZ
TO -RA SUN MORNING WITH DEEPER MOISTURE AND ONE STRONGER SURGE OF
850- 700MB WARM ADVECTION LIFTING ACROSS THE AREA. BIT OF A LULL
IN THE LIFT SUN NIGHT WITH THE INCREASE OF DYNAMIC LIFT/PV
ADVECTION AHEAD OF THE TROUGH/SHORTWAVE MOVING ACROSS MON/MON
NIGHT. RAISED PRECIP CHANCES MON INTO MON NIGHT. ADDED PATCHY FOG
FOR SUN NIGHT/MON MORNING AS WELL WITH INCREASING DEW POINTS OVER
THE COLD GROUND. TRENDED PRECIP SUN NIGHT THRU MON NIGHT TOWARD
MORE -RA AS MODEL SOUNDINGS AND X-SECTIONS FOR THIS PERIOD SHOWING
AT LEAST THE SFC- 900MB LAYER WARMING INTO THE 0C TO +3C RANGE...
ESPECIALLY OVER THE CENTRAL/SOUTH PARTS OF THE FCST AREA. LINGERED
A -SN CHANCE MAINLY DURING THE NIGHTTIME/EARLY MORNING HOURS WITH
A COOLER BOUNDARY LAYER AND ANY HEAVIER PRECIP RATES IF THEY OCCUR
CAPABLE OF COOLING THE COLUMN ENOUGH FOR SNOWFLAKES TO REACH THE
GROUND. WILL ALSO HAVE TO WATCH THE LATE NIGHT/EARLY MORNING HOURS
OF SUN/MON NIGHTS FOR -FZRA ON COLD GROUND SURFACES. USED A BLEND
OF THE GUIDANCE HIGHS/ LOWS FOR SUN THRU MON NIGHT...RAISING LOWS
A BIT SUN NIGHT WITH THE SOUTHERLY BOUNDARY LAYER FLOW/THICK LOW
CLOUDS OVER THE AREA.

FOR TUESDAY THRU FRIDAY...DAYS 4 TO 7...

MAIN FORECAST CONCERNS THIS PERIOD...PRECIP CHANCES/TYPES TUE/WED
AND AGAIN FRI...TEMPERATURES.

MEDIUM RANGE MODEL RUNS OF 19.00Z/19.12Z IN QUITE GOOD AGREEMENT TUE
WITH THE TROUGH DEEPENING OVER THE CENTRAL CONUS. TREND FAVORS
SLOWER/STRONGER OF THE EARLIER RUNS. CONSISTENCY REMAINS GOOD FOR
THE TROUGH TO BE PROGRESSIVE INTO THE EASTERN CONUS WED/THU AS
STRONG ENERGY ROTATES UP THE EAST SIDE OF THE TROUGH. IMPROVING
SIGNAL FOR SHORTWAVE RIDGING TO BUILD OVER THE MID/UPPER MS VALLEY
FOR CHRISTMAS DAY...AS ONE TROUGH LIFTS INTO THE CAN MARITIMES AND
MORE ENERGY DIGS INTO THE CENTRAL/SOUTHERN ROCKIES. POTENTIAL FOR
SOME PORTION OF THE ENERGY TO LIFT TOWARD/INTO THE MID/UPPER MS
VALLEY FRI. PLENTY OF SPREAD AMONG THE MODELS AND ENSEMBLE
MEMBERS WITH THE DETAILS BY DAY 7. CONFIDENCE IN THE DAY 4-7
PERIOD IS AVERAGE TO GOOD TUE-THU THEN AVERAGE TO BELOW FOR FRI.

IMPROVING MODEL CONSENSUS FOR THE SFC-700MB LOW TO BE OCCLUDING/
AS IT MOVES ACROSS THE UPPER MIDWEST TUE. FORCING/LIFT OVER THE
FCST AREA WEAKENS THRU TUE/TUE NIGHT WITH THE MOISTURE CONVEYOR
BEING PUSHED FURTHER FROM THE AREA BY THE OCCLUSION. COLUMN DOES
COOL TUE AS THE OCCLUDING LOW/MID LEVEL TROUGH AXIS PASS. HIGHER
CHANCES OF PRECIP TUE/TUE NIGHT AS A DEFORMATION BAND WOULD
ROTATE ACROSS THE AREA. MIX OF -RA/-SN TUE MORNING GIVING WAY TO
-SN FOR LATE TUE/TUE NIGHT. STRONG ENERGY IN THE SOUTHERN PORTION
OF THE LONGWAVE TROUGH ROTATING UP THE EASTERN SEABOARD WED DRAGS
THE MID LEVEL LOW INTO THE EASTERN GREAT LAKES BY WED NIGHT...
SPREADING DRYING NORTHWEST 850-500MB FLOW OVER THE REGION. ANY
LINGERING -SN LOOKING TO TAPER OFF FROM SOUTHWEST TO NORTHEAST
WED/WED EVENING. SFC THRU MID LEVEL RIDGING PROGGED TO SLIDE
ACROSS THE UPPER MIDWEST THU...WITH OUR BEST SHOT AT SOME SUNSHINE
NEXT WEEK ON CHRISTMAS DAY. CONFIDENCE AVERAGE AT BEST FRI BUT
LATEST DETERMINISTIC MODEL RUNS WOULD LIFT A PORTION OF THE
ROCKIES ENERGY INTO THE UPPER MIDWEST AT THE END OF THE WEEK.
PLENTY OF LOWER LEVEL DETAIL DIFFERENCES BY FRI WITH ANY
POTENTIAL SFC LOW TRACK/STRENGTH AND HOW MUCH WARM AIR IS DRAWN
NORTH AHEAD OF THE SYSTEM FOR PRECIP TYPE ISSUES. WILL STAY WITH
THE MODEL/ENSEMBLE CONSENSUS ON FRI FOR NOW. MODEL/ENSEMBLE
CONSENSUS OF HIGHS/LOWS FOR TUE-FRI SEEMS TO HAVE THEM WELL
TRENDED AS WELL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1133 AM CST FRI DEC 19 2014

IFR CEILINGS/MVFR VISIBILITY IN MIST IS STAYING JUST WEST OF
KRST/KLSE ACROSS MUCH OF CENTRAL MN/IA LATE THIS MORNING. LATEST
FORECAST GUIDANCE SUGGESTS THESE LOW CLOUDS WILL SLOWLY PUSH EAST
THROUGH THE PERIOD...BUT WITH A PREDOMINANT SOUTH WIND...DELAYED
ONSET OF LOWER CEILINGS AT KRST UNTIL 19.22Z AND AT KLSE UNTIL
20.03Z. PATCHY FREEZING DRIZZLE POSSIBLE OVERNIGHT...BUT COVERAGE
UNCERTAINTY PRECLUDES MENTION IN 19.18Z TAFS. WILL NEED TO WATCH
FOR A FURTHER LOWERING OF CEILINGS/VISIBILITY IN THE HOURS AROUND
DAYBREAK SATURDAY MORNING. OTHERWISE...CONDITIONS SHOULD REBOUND
SLIGHTLY NEAR THE END OF THE PERIOD. SOUTHERLY WINDS WILL
CONTINUE...GENERALLY 10 KTS OR LESS.

&&

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

$$

SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....ROGERS





000
FXUS63 KARX 191733
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1133 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1133 AM CST FRI DEC 19 2014

IFR CEILINGS/MVFR VISIBILITY IN MIST IS STAYING JUST WEST OF
KRST/KLSE ACROSS MUCH OF CENTRAL MN/IA LATE THIS MORNING. LATEST
FORECAST GUIDANCE SUGGESTS THESE LOW CLOUDS WILL SLOWLY PUSH EAST
THROUGH THE PERIOD...BUT WITH A PREDOMINANT SOUTH WIND...DELAYED
ONSET OF LOWER CEILINGS AT KRST UNTIL 19.22Z AND AT KLSE UNTIL
20.03Z. PATCHY FREEZING DRIZZLE POSSIBLE OVERNIGHT...BUT COVERAGE
UNCERTAINTY PRECLUDES MENTION IN 19.18Z TAFS. WILL NEED TO WATCH
FOR A FURTHER LOWERING OF CEILINGS/VISIBILITY IN THE HOURS AROUND
DAYBREAK SATURDAY MORNING. OTHERWISE...CONDITIONS SHOULD REBOUND
SLIGHTLY NEAR THE END OF THE PERIOD. SOUTHERLY WINDS WILL
CONTINUE...GENERALLY 10 KTS OR LESS.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ROGERS




000
FXUS63 KARX 191733
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1133 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1133 AM CST FRI DEC 19 2014

IFR CEILINGS/MVFR VISIBILITY IN MIST IS STAYING JUST WEST OF
KRST/KLSE ACROSS MUCH OF CENTRAL MN/IA LATE THIS MORNING. LATEST
FORECAST GUIDANCE SUGGESTS THESE LOW CLOUDS WILL SLOWLY PUSH EAST
THROUGH THE PERIOD...BUT WITH A PREDOMINANT SOUTH WIND...DELAYED
ONSET OF LOWER CEILINGS AT KRST UNTIL 19.22Z AND AT KLSE UNTIL
20.03Z. PATCHY FREEZING DRIZZLE POSSIBLE OVERNIGHT...BUT COVERAGE
UNCERTAINTY PRECLUDES MENTION IN 19.18Z TAFS. WILL NEED TO WATCH
FOR A FURTHER LOWERING OF CEILINGS/VISIBILITY IN THE HOURS AROUND
DAYBREAK SATURDAY MORNING. OTHERWISE...CONDITIONS SHOULD REBOUND
SLIGHTLY NEAR THE END OF THE PERIOD. SOUTHERLY WINDS WILL
CONTINUE...GENERALLY 10 KTS OR LESS.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ROGERS





000
FXUS63 KARX 191140
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 540 AM CST FRI DEC 19 2014

EXTENSIVE DECK OF MVFR CLOUD COVER IN PLACE ACROSS THE REGION.
THERE IS A THIN SLIVER OF VFR CLOUD CIGS EXTENDING FROM VCNTY KRST
SOUTHEASTWARD INTO NORTHEAST IA...BUT THINKING THIS WILL QUICKLY
FILL IN WITH MVFR CLOUD AS WELL THIS MORNING. IN ADDITION...SOME
PATCHY FREEZING DRIZZLE MAY SEEN ACROSS PORTIONS OF NORTHEAST IA
INTO SOUTHEAST MN BY MID-MORNING INTO THIS AFTERNOON AS SOUTHERLY
FLOW BRINGS MORE MOISTURE INTO THE AREA AHEAD OF A TROUGH OF LOW
PRESSURE MOVING OUT OF THE PLAINS.EXPECTING PATCHY FREEZING
DRIZZLE TO SPREAD EAST OF THE MISSISSIPPI LATER TONIGHT INTO
SATURDAY MORNING AS THE TROUGH MOVES INTO THE REGION. SINCE THIS
FREEZING DRIZZLE IS EXPECTED TO BE PATCHY IN NATURE...DECIDED TO
KEEP OUT OF THE BODY OF THE TAF FOR NOW...BUT WILL CONTINUE TO
MONITOR CLOSELY. OTHERWISE...LOOK FOR KRST CIGS TO SLIP FROM MVFR
TODAY INTO IFR AFTER 04Z.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS




000
FXUS63 KARX 191140
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 540 AM CST FRI DEC 19 2014

EXTENSIVE DECK OF MVFR CLOUD COVER IN PLACE ACROSS THE REGION.
THERE IS A THIN SLIVER OF VFR CLOUD CIGS EXTENDING FROM VCNTY KRST
SOUTHEASTWARD INTO NORTHEAST IA...BUT THINKING THIS WILL QUICKLY
FILL IN WITH MVFR CLOUD AS WELL THIS MORNING. IN ADDITION...SOME
PATCHY FREEZING DRIZZLE MAY SEEN ACROSS PORTIONS OF NORTHEAST IA
INTO SOUTHEAST MN BY MID-MORNING INTO THIS AFTERNOON AS SOUTHERLY
FLOW BRINGS MORE MOISTURE INTO THE AREA AHEAD OF A TROUGH OF LOW
PRESSURE MOVING OUT OF THE PLAINS.EXPECTING PATCHY FREEZING
DRIZZLE TO SPREAD EAST OF THE MISSISSIPPI LATER TONIGHT INTO
SATURDAY MORNING AS THE TROUGH MOVES INTO THE REGION. SINCE THIS
FREEZING DRIZZLE IS EXPECTED TO BE PATCHY IN NATURE...DECIDED TO
KEEP OUT OF THE BODY OF THE TAF FOR NOW...BUT WILL CONTINUE TO
MONITOR CLOSELY. OTHERWISE...LOOK FOR KRST CIGS TO SLIP FROM MVFR
TODAY INTO IFR AFTER 04Z.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS





000
FXUS63 KARX 190933
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
333 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1026 PM CST THU DEC 18 2014

SOME CHANGES HAVE BEEN MADE TO THE PREVIOUS AVIATION FORECAST...
WHICH BEGUN ON A 0130Z AMENDMENT TO RST. MVFR STRATUS STILL
PERSISTS OVER THE TAF SITES. HOWEVER...A WEDGE OF DRY AIR BELOW AN
ALTOSTRATUS DECK HAS MADE ITS WAY FROM I-35 TOWARDS RST. RST
SHOULD GO VFR FOR THE START OF THE TAF PERIOD AS A SOUTHWEST WIND
AT THE HEIGHT OF THE CLOUDS PUSHES THE DRY AIR EASTWARD. IN
FACT...THIS DRYING COULD MAKE IT ALL THE WAY TO LSE LATER IN THE
MORNING...BETWEEN 15-19Z TO ALLOW FOR TEMPORARY SCATTERING OUT
THERE. LATE IN THE AFTERNOON...AROUND 20Z...MVFR STRATUS OVER
WESTERN IA AND MN LOOKS TO MOVE INTO RST. MEANWHILE...LIGHT FLOW
SHOULD ALLOW MVFR STRATUS TO REASSERT ITSELF AT LSE. ANTICIPATING
THEN CONDITIONS TO STAY MVFR INTO THE EVENING AS THE TWO STRATUS
DECKS MERGE UP.


&&

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

$$

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




000
FXUS63 KARX 190933
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
333 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1026 PM CST THU DEC 18 2014

SOME CHANGES HAVE BEEN MADE TO THE PREVIOUS AVIATION FORECAST...
WHICH BEGUN ON A 0130Z AMENDMENT TO RST. MVFR STRATUS STILL
PERSISTS OVER THE TAF SITES. HOWEVER...A WEDGE OF DRY AIR BELOW AN
ALTOSTRATUS DECK HAS MADE ITS WAY FROM I-35 TOWARDS RST. RST
SHOULD GO VFR FOR THE START OF THE TAF PERIOD AS A SOUTHWEST WIND
AT THE HEIGHT OF THE CLOUDS PUSHES THE DRY AIR EASTWARD. IN
FACT...THIS DRYING COULD MAKE IT ALL THE WAY TO LSE LATER IN THE
MORNING...BETWEEN 15-19Z TO ALLOW FOR TEMPORARY SCATTERING OUT
THERE. LATE IN THE AFTERNOON...AROUND 20Z...MVFR STRATUS OVER
WESTERN IA AND MN LOOKS TO MOVE INTO RST. MEANWHILE...LIGHT FLOW
SHOULD ALLOW MVFR STRATUS TO REASSERT ITSELF AT LSE. ANTICIPATING
THEN CONDITIONS TO STAY MVFR INTO THE EVENING AS THE TWO STRATUS
DECKS MERGE UP.


&&

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

$$

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





000
FXUS63 KARX 190933
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
333 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1026 PM CST THU DEC 18 2014

SOME CHANGES HAVE BEEN MADE TO THE PREVIOUS AVIATION FORECAST...
WHICH BEGUN ON A 0130Z AMENDMENT TO RST. MVFR STRATUS STILL
PERSISTS OVER THE TAF SITES. HOWEVER...A WEDGE OF DRY AIR BELOW AN
ALTOSTRATUS DECK HAS MADE ITS WAY FROM I-35 TOWARDS RST. RST
SHOULD GO VFR FOR THE START OF THE TAF PERIOD AS A SOUTHWEST WIND
AT THE HEIGHT OF THE CLOUDS PUSHES THE DRY AIR EASTWARD. IN
FACT...THIS DRYING COULD MAKE IT ALL THE WAY TO LSE LATER IN THE
MORNING...BETWEEN 15-19Z TO ALLOW FOR TEMPORARY SCATTERING OUT
THERE. LATE IN THE AFTERNOON...AROUND 20Z...MVFR STRATUS OVER
WESTERN IA AND MN LOOKS TO MOVE INTO RST. MEANWHILE...LIGHT FLOW
SHOULD ALLOW MVFR STRATUS TO REASSERT ITSELF AT LSE. ANTICIPATING
THEN CONDITIONS TO STAY MVFR INTO THE EVENING AS THE TWO STRATUS
DECKS MERGE UP.


&&

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

$$

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




000
FXUS63 KARX 190933
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
333 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE MAIN FORECAST CHALLENGE INTO TONIGHT IS WITH THE LOW LEVEL
MOISTURE AND WHETHER IT WILL BE ENOUGH TO PRODUCE SOME FREEZING
DRIZZLE OR FLURRIES.

CURRENTLY...A BAND OF 1-2KFT STRATUS THAT EXTENDS FROM NORTHWEST
WISCONSIN DOWN THROUGH SOUTHERN WISCONSIN HAS BEEN PRODUCING SOME
FLURRIES DUE TO SOME WEAK LIFT ASSOCIATED WITH A COLD FRONT THAT
EXTENDS FROM SOUTHERN MICHIGAN WEST-NORTHWEST INTO WESTERN
WISCONSIN. THIS FEATURE WILL PULL EASTWARD THIS MORNING/AFTERNOON
AND SHOULD TAKE THESE FLURRIES EAST AS WELL. TO THE SOUTHWEST
TOWARD DES MOINES...ANOTHER BAND OF LOW LEVEL MOISTURE ASSOCIATED
WITH SOME RETURN SOUTHERLY FLOW/WARM AIR ADVECTION HAS FORMED SOME
FREEZING DRIZZLE AND FLURRIES IN THAT REGION. THE QUESTION FOR
TODAY/TONIGHT IS WHETHER THAT FREEZING DRIZZLE/FLURRIES HOLDS
TOGETHER.

19.00Z NAM/GFS AND 19.06Z RAP SOUNDINGS CERTAINLY SHOW THE SURFACE
TO 800MB LAYER MOISTENING UP THROUGH TONIGHT...ITS JUST A MATTER
OF WHETHER THERE IS ANY LIFT THERE. GIVEN THAT THERE CURRENTLY IS
SOME PRECIPITATION OCCURRING UPSTREAM...THERE DOES APPEAR TO BE
ENOUGH LIFT AND HAVE GONE AHEAD AND ADDED A MENTION OF SOME
PATCHY FREEZING DRIZZLE IN FOR TODAY IN SE MN/NE IA WITH IT
SPREADING EASTWARD OVERNIGHT AS THE MOISTURE SHIFTS EAST. DMX HAS
REPORTED SOME FLURRIES OCCURRING AS WELL AT THE MOMENT MEANING
THAT THERE IS SOME ICE BEING INTRODUCED IN THE LOW LEVELS THOUGH
MOST OF THE FORECAST SOUNDINGS SHOW THAT SATURATED LAYER BEING TOO
WARM TONIGHT TO PRODUCE ANY FLURRIES LOCALLY. NOT SURE WHETHER
THIS FREEZING DRIZZLE IS GOING TO BE ADVISORY WORTHY GIVEN THAT
THERE IS NOT MUCH FOCUS FOR LOW LEVEL LIFT...BUT CONDITIONS WILL
HAVE TO BE MONITORED SINCE AIR/ROAD TEMPERATURES WILL BE BELOW
FREEZING.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 333 AM CST FRI DEC 19 2014

THE PATTERN BECOMES MORE ACTIVE GOING INTO THE LATER PORTION OF
THE WEEKEND ON INTO EARLY NEXT WEEK AS A SERIES OF MID LEVEL SHORT
WAVE TROUGHS PROPAGATE ON THROUGH. THE NEXT DECENT CHANCE FOR
PRECIPITATION APPEARS TO COME IN ON SUNDAY AS LOW LEVEL WARM AIR
ADVECTION WILL COMBING WITH SOME WEAK 700MB TROUGHING TO DEVELOP
SOME PRECIPITATION. PRECIPITATION TYPE IS TRICKY WITH THIS SYSTEM
AS THERE IS A WEAK WARM LAYER THAT REACHES +1 TO +2C AND WOULD
MELT SOME OF THE SNOW THAT FALLS THROUGH IT. THERE ALSO APPEARS
TO BE A DRY LAYER BETWEEN THE 700MB MOISTURE AND SURFACE/LOW LEVEL
MOISTURE WHICH BRINGS INTO QUESTION HOW DEEP THE LIFT REALLY WILL
BE. SURFACE TEMPERATURES WILL ALSO BE CLIMBING TOWARD AND ABOVE
FREEZING WHICH COMPLICATES HOW MUCH SNOW COULD ACCUMULATE. KEPT
SNOW ACCUMULATIONS ON THE LOW SIDE...HALF INCH OR LESS...GIVEN ALL
OF THE QUESTIONS WITH THIS ROUND OF PRECIP.

A DEEPER TROUGH DEVELOPS ACROSS THE DAKOTAS SUNDAY NIGHT INTO
TUESDAY AND WILL BRING A MORE WIDESPREAD SHOT OF
PRECIPITATION...MAINLY RAIN BEFORE CHANGING OVER TO SNOW ON THE
BACKSIDE TUESDAY. THE 19.00Z GFS/ECMWF ARE IN DECENT AGREEMENT
WITH THIS SYSTEM IN REGARD TO TIMING BUT ARE DIFFERENT WITH THEIR
PROGRESSION OF THE SURFACE LOW WITH THE GFS DIGGING DEEPER EARLIER
WITH THE ECMWF KEEPING PRECIPITATION AROUND A TAD LONGER. BOTH
MODELS HAVE THE SNOW OFF TO THE EAST BY CHRISTMAS DAY WITH JUST
SOME WEST TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1026 PM CST THU DEC 18 2014

SOME CHANGES HAVE BEEN MADE TO THE PREVIOUS AVIATION FORECAST...
WHICH BEGUN ON A 0130Z AMENDMENT TO RST. MVFR STRATUS STILL
PERSISTS OVER THE TAF SITES. HOWEVER...A WEDGE OF DRY AIR BELOW AN
ALTOSTRATUS DECK HAS MADE ITS WAY FROM I-35 TOWARDS RST. RST
SHOULD GO VFR FOR THE START OF THE TAF PERIOD AS A SOUTHWEST WIND
AT THE HEIGHT OF THE CLOUDS PUSHES THE DRY AIR EASTWARD. IN
FACT...THIS DRYING COULD MAKE IT ALL THE WAY TO LSE LATER IN THE
MORNING...BETWEEN 15-19Z TO ALLOW FOR TEMPORARY SCATTERING OUT
THERE. LATE IN THE AFTERNOON...AROUND 20Z...MVFR STRATUS OVER
WESTERN IA AND MN LOOKS TO MOVE INTO RST. MEANWHILE...LIGHT FLOW
SHOULD ALLOW MVFR STRATUS TO REASSERT ITSELF AT LSE. ANTICIPATING
THEN CONDITIONS TO STAY MVFR INTO THE EVENING AS THE TWO STRATUS
DECKS MERGE UP.


&&

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

$$

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





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