Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 231140
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CST FRI JAN 23 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CST FRI JAN 23 2015

THE MAIN FOCUS FOR THE EARLY PART OF THE FORECAST IS ON THE
POTENTIAL FOR FREEZING RAIN AND SLEET THIS MORNING.

CURRENTLY...A NORTHEAST TO SOUTHWEST ORIENTED MID LEVEL SHORT WAVE
TROUGH IS DROPPING SOUTH INTO NORTHERN MINNESOTA WITH A BAND OF
LIGHT PRECIPITATION OUT AHEAD OF IT. AT THE SURFACE/LOW LEVELS...A
NORTH TO SOUTH ORIENTED WARM FRONT IS ADVANCING SOUTHEASTWARD AS
WELL ACROSS MINNESOTA WITH THIS WARM LAYER CAUSING SOME
PRECIPITATION TYPE ISSUES IN NORTHERN MINNESOTA. EVEN THOUGH
SURFACE TEMPERATURES HAVE CLIMBED ABOVE FREEZING...ROAD
TEMPERATURES ARE STILL BELOW FREEZING AND IS CAUSING SOME ICY
CONDITIONS. SIMILAR CONDITIONS ARE NOTED LOCALLY WITH ROAD SENSORS
SAYING ROAD TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO AROUND
30.

THE QUESTION LOCALLY IS WITH HOW MUCH OF THIS PRECIPITATION WILL
MAKE IT DOWN HERE AND HOW FAR SOUTHEAST WILL THE WARM LAYER MAKE
IT. 23.07Z RAP SOUNDINGS SHOW A SUBSTANTIAL DRY LAYER IN THE
LOWEST 5-6KFT OF THE PROFILE IN MOST SITES FROM POINTS SOUTH OF
SOUTHEAST MINNESOTA GOING EAST THROUGH CENTRAL WISCONSIN. FURTHER
NORTH...HOWEVER...TOWARD NORTH CENTRAL WISCONSIN THE POTENTIAL IS
THERE FOR DEEPER SATURATION AND A HIGHER CHANCE FOR PRECIPITATION.
THE WARM LAYER APPEARS TO CREEP UP TOWARD 1 TO 3C ABOVE
FREEZING...SO THERE WILL LIKELY BE SOME MELTING OF ANY ICE/SNOW
THAT TRIES TO FALL THROUGH THE COLUMN. THE WARMER PART OF THE WARM
NOSE APPEARS TO DROP DOWN FROM FAR NORTHWEST WISCONSIN DOWN TO
SOUTHEAST MINNESOTA/NORTH CENTRAL IOWA THIS MORNING...SO THE MAIN
PRECIPITATION TYPE THERE WOULD BE RAIN...IF IT PRECIPITATES. SAY
THAT IT DOES OCCUR...THE QUESTION BECOMES WHAT ROAD TEMPERATURES
WILL DO THROUGH THE MORNING.

OVERALL CONFIDENCE IS HIGHEST IN TAYLOR COUNTY THAT SOME ISSUES
WILL OCCUR WITH FREEZING RAIN/SLEET...SO WILL ADD THEM TO THE
ADVISORY. SHOULD THE PRECIPITATION MAKE IT FURTHER SOUTH...THEN A
SOUTHWARD EXPANSION TO THE ADVISORY MAY BE NEEDED...BUT CONFIDENCE
IS NOT HIGH ENOUGH AT THIS POINT TO DO THAT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 340 AM CST FRI JAN 23 2015

THE MAIN FOCUS IN THE EXTENDED PERIOD IS WITH THE SNOW AMOUNTS ON
SATURDAY NIGHT INTO SUNDAY AS A LOW PRESSURE SYSTEM DROPS DOWN
FROM SOUTHERN CANADA. CONFIDENCE IS HIGH THAT THIS SYSTEM WILL BE
MOVING THROUGH IN THE SATURDAY NIGHT/SUNDAY TIME FRAME...BUT
CONFIDENCE IS RATHER LOW WITH THE TRACK OF THE SYSTEM. THE 23.00Z
ECMWF IS THE FURTHEST SOUTH WITH THE LEAST AMOUNT OF SNOW...THE
23.00Z NAM IS THE SLOWEST AND HAS THE NARROWEST BAND MOVING
THROUGH WEST CENTRAL WISCONSIN AND THE 23.00Z GFS IS SOMEWHERE IN
BETWEEN THESE TWO WITH THE MOST WIDESPREAD AND HEAVIEST SNOW. AT
THIS POINT...CAN ONLY TAKE THE MIDDLE OF THE ROAD WHICH ENDS UP
BEING CLOSE TO THE GFS PATH WITH LESS QPF. STILL...WITH SNOW
RATIOS OF AROUND 13:1 AND QPF OF AROUND A QUARTER OF AN
INCH...COULD SEE SOME 2 TO 4 INCH SNOWS FROM THIS QUICK MOVING
SYSTEM. INCREASED THE PRECIPITATION CHANCES FOR THE EVENT SINCE
IT IS LOOKING LIKE MOST OF THE REGION WILL SEE SOME SNOW...IT IS
JUST A MATTER OF HOW MUCH.

BEYOND THIS...ONLY MADE SOME ADJUSTMENTS TO THE WEDNESDAY HIGH
TEMPERATURE FORECAST FOR WHAT APPEARS TO BE A STRONG SOUTHERLY
FLOW DAY WITH A WARM AIR MASS MOVING IN FROM THE SOUTH.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 540 AM CST FRI JAN 23 2015

INCREASING SOUTHWEST LOW LEVEL FLOW HAS FINALLY PUSHED THE MVFR
CLOUD DECK EAST AND OUT OF THE TAF SITES. GENERALLY GOOD VFR
CONDITIONS EXPECTED TODAY...WITH MODERATE SOUTHWEST WINDS OF 10-
20KTS. A COLD FRONT WILL DROP SOUTH ACROSS THE AREA LATE THIS
AFTERNOON/EARLY THIS EVENING. LOW LEVEL MOISTURE WILL ONCE AGAIN
INCREASE ACROSS THE AREA BEHIND THIS FRONT. MVFR CLOUD DECKS TO MOVE
INTO THE TAF SITES VERY LATE THIS AFTERNOON...THEN PERSIST THRU
TONIGHT. WITH DIURNAL COOLING...CLOUD HGTS EXPECTED TO DROP TO IFR
AT KRST BY MID EVENING. NORTHWEST WINDS 10-15KT ALSO SPREAD ACROSS
THE AREA BEHIND THE FRONT FOR TONIGHT.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR WIZ017.

MN...NONE.
IA...NONE.
&&

$$

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


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