Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 021716
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1116 AM CST MON MAR 2 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CST MON MAR 2 2015

THE MAIN FOCUS IS ON THE OVERNIGHT PERIOD AND WHEN SNOW WILL
DEVELOP ACROSS THE REGION.

CURRENTLY...A BROAD SURFACE RIDGE OF HIGH PRESSURE IS IN PLACE
ACROSS MUCH OF THE CENTRAL CONUS WITH SKIES MAINLY CLEAR DUE TO
THE AMOUNT OF DRY AIR/SUBSIDENCE.

HIGH LEVEL CLOUD COVER WILL BE ON THE INCREASE GOING INTO THIS
AFTERNOON AS A 700MB SHORT WAVE TROUGH LIFTS UP INTO THE REGION.
02.00Z MODEL TRENDS ARE FAVORING A SLOWER SATURATION TO THE COLUMN
AS LOW LEVEL WARM AIR ADVECTION LIFTS UP INTO THE REGION. THE
GENERAL CONSENSUS APPEARS TO BE THAT SATURATION WILL OCCUR AFTER
MIDNIGHT ON TOWARD DAYBREAK AS THE LOW/MID LEVEL TROUGH APPROACHES
FROM THE SOUTHWEST. WITH THE WEAK LIFT BATTLING THE DRY AIR
INITIALLY...EXPECT THAT SNOW TOTALS SHOULD GENERALLY STAY ON THE
LIGHT SIDE OVERNIGHT AT AN INCH OR LESS.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 345 AM CST MON MAR 2 2015

THE MAIN CONCERN/QUESTION CONTINUES TO BE WITH WHAT TO DO WITH
THE TUESDAY SYSTEM AS IT OFFERS UP A NUMBER OF ISSUES...ONE BEING
GENERAL CONFIDENCE IN HOW THE SYSTEM WILL PAN OUT. THE FIRST
THREAT COMES FROM THE SNOW WHICH DEVELOPS EARLY TUESDAY MORNING
AND ACCUMULATES THE MOST BETWEEN 6AM-12PM TUESDAY BEFORE LETTING
UP IN THE AFTERNOON. CONFIDENCE REMAINS LOW WITH HOW MUCH SNOW
WILL FALL AS THE 02.00Z GUIDANCE IS STILL ALL OVER THE PLACE WITH
THE TRACK OF THE SURFACE LOW/WARM LAYER. THE OUTLIER NAM CONTINUES
TO HAVE THE FURTHEST NORTH TRACK AND WOULD MEAN LITTLE TO NO SNOW
FOR THE AREA AND MORE OF A MIX/FREEZING DRIZZLE SCENARIO DUE TO A
LOSS OF ICE IN THE WARM SECTOR. WPC CONTINUES TO FAVOR A BLEND OF
THE GFS/ECMWF...SO HAVE ALSO FOLLOWED THAT BLEND AS WELL. THE GFS
DOES BRING THE WARM LAYER A BIT FURTHER NORTHEAST INTO SOUTHERN
WISCONSIN...SO THERE IS A SMALL POTENTIAL FOR SOME SLEET/FREEZING
DRIZZLE IN THAT AREA TUESDAY MORNING. QPF TRENDS ARE GOING DOWN AS
WELL DUE TO THE LOW RESIDENCE TIME OF THE SNOW FROM THE QUICK
MOVEMENT OF THE SURFACE LOW. THE HEAVIEST SNOW BAND WILL LIKELY BE
TO THE NORTHWEST OF THE LOCAL AREA WITH THE DEFORMATION BAND GOING
FROM EASTERN SOUTH DAKOTA INTO CENTRAL MINNESOTA. STILL...HAVE A
DECENT PROBABILITY OF SEEING SOME 4" SNOWS IN NORTH CENTRAL
WISCONSIN DUE TO THE COMBINATION OF SOME HIGHER SNOW:LIQUID
RATIOS.

ONCE THE LOW/COLD FRONT MOVE THROUGH TUESDAY AFTERNOON...WINDS
WILL INCREASE OUT OF THE WEST NORTHWEST AND CAUSE SOME
BLOWING/DRIFTING OF SNOW...PARTICULARLY IN THE WIND PRONE AREAS OF
NORTHEAST IOWA/SOUTHEAST MINNESOTA. THIS SHOULD CAUSE SOME ISSUES
GOING INTO THE AFTERNOON COMMUTE...BUT CONFIDENCE IS DECREASING A
BIT IN HOW BAD IT WILL BE DUE TO LOWERING SNOWFALL AMOUNTS. DUE TO
THIS...WAS NOT CONFIDENT ENOUGH TO GO WITH A BLIZZARD WARNING
THOUGH WINDS WILL BE STRONGER TO THE WEST THROUGH SOUTHERN
MINNESOTA WHERE MPX WILL BE GOING WITH A BLIZZARD WARNING.
STILL...A FRESH 2-3 INCHES SHOULD BE ENOUGH TO BLOW AROUND FOR AT
LEAST A SMALL PERIOD TUESDAY AFTERNOON AND CAUSE SOME ISSUES.
ACROSS WESTERN WISCONSIN...CONDITIONS WILL LIKELY NOT BE AS BAD
DUE TO LIGHTER WINDS AND A LOWER SNOW:LIQUID RATIO CONTENT TO THE
NEW SNOW.

WENT BACK AND FORTH ON WHETHER OR NOT TO ISSUE AN ADVISORY...BUT
IN THE END IT APPEARS THAT CONDITIONS WILL BE BAD ENOUGH TO
WARRANT ONE. ENOUGH NEIGHBORING OFFICES WANTED TO DO HEADLINES AS
WELL...SO WE HAVE STARTED THE ADVISORY AT 3AM TUESDAY MORNING TO
COVER THE DEVELOPING SNOW FOR THE MORNING COMMUTE AND ENDED IT AT
9 PM TUESDAY EVENING TO COVER THE BLOWING SNOW. A PORTION OF THE
ADVISORY ACROSS WESTERN WISCONSIN MAY BE ABLE TO BE ENDED EARLY IF
THE BLOWING SNOW DOES NOT BECOME AN ISSUE THERE.

BEHIND THIS SYSTEM...COLDER AIR WILL MOVE INTO THE REGION WITH
WIND CHILL ADVISORIES POSSIBLY BEING NEEDED WEDNESDAY AND THURSDAY
MORNINGS. THEN A WARMING TREND TAKES PLACE INTO THE WEEKEND WITH
TEMPERATURES LOOKING LIKE THEY WILL GO BACK ABOVE FREEZING FOR A
PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY NOON)
ISSUED AT 1116 AM CST MON MAR 2 2015

GOOD VFR CONDITIONS EXPECTED THIS AFTERNOON/EVENING AS HIGH PRESSURE
HOLDS BUT ITS CENTER SLOWLY DRIFTS EAST OF THE AREA. CLOUDS THRU
MIDNIGHT INTO THE EARLY OVERNIGHT HOURS TO BE MAINLY MID/HIGH
CLOUDS. SOUTHEAST GRADIENT WINDS WILL INCREASE TONIGHT AS THE
PRESSURE GRADIENT TIGHTENS AHEAD OF LOW PRESSURE MOVING INTO THE
CENTRAL PLAINS. MOISTURE/FORCING/LIFT AHEAD OF THIS LOW SPREADS
INTO/ACROSS THE TAF SITES LATE TONIGHT/TUE MORNING. CONDITIONS
EXPECTED TO QUICKLY DROP TO IFR ONCE SNOW SPREADS INTO THE TAF SITES
IN THE 09-11Z TIME-FRAME. IFR VSBYS...IFR/MVFR CIGS THEN EXPECTED
THRU TUE MORNING AS THE LOW APPROACHES. STRONGEST OF THE LIFT/
HEAVIEST OF THE SNOW LOOKS TO MOVE ACROSS THE TAF SITES IN THE 09-
15Z PERIOD AT KRST AND 12-16Z AT KLSE...WITH VSBYS IMPROVING FOR THE
LATE MORNING HOURS. SNOW AMOUNTS OF 1 TO 2 INCHES EXPECTED AT BOTH
KRST/KLSE LATE TONIGHT/TUE MORNING.

SNOW ENDS EARLY TUE AFTERNOON...BUT STRONG PRESSURE GRADIENT...
NORTHWEST WINDS G30-35KTS THEN EXPECTED TO SPREAD ACROSS THE TAF
SITES WITH BLOWING/DRIFTING SNOW FOR THE MID/LATE AFTERNOON HOURS.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM CST TUESDAY FOR WIZ017-
     029-032>034-041>044-053>055-061.

MN...WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM CST TUESDAY FOR MNZ079-
     086>088-094>096.

IA...WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM CST TUESDAY FOR
     IAZ008>011-018-019-029-030.

&&

$$

SHORT TERM...HALBACH
LONG TERM....HALBACH
AVIATION.....RRS


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