Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 250534
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1134 PM CST SAT JAN 24 2015

.UPDATE...
ISSUED AT 538 PM CST SAT JAN 24 2015

MADE TWO ADJUSTMENTS TO THE FORECAST FOR TONIGHT AND SUNDAY.

THE FIRST IS RELATED TO A SOUTH/SOUTHWESTWARD TREND IN POP/QPF
FROM 24.15Z SREF...24.18Z NAM AND LATEST RAP/HRRR RUNS. THIS SEEMS
REASONABLE AS THE SHORTWAVE TROUGH RESPONSIBLE FOR THE
PRECIPITATION OVER THE NEXT 18 HOURS CONTINUES TO DIG MORE TO THE
SOUTH ON THE LATEST WATER VAPOR LOOP...VERSUS SOUTHEAST. HAVE
SHIFTED THE POPS SLIGHTLY SOUTHWESTWARD...ESPECIALLY FOR 06-18Z
SUNDAY WHERE THE NORTHERN PART OF THE FRONTOGENETIC CIRCULATION
HELPS TO DRAG DRIER AIR INTO THE FORECAST AREA.

THE SECOND ADJUSTMENT IS RELATED TO PRECIPITATION TYPE.
TEMPERATURES WARMED UP MUCH MORE THAN EXPECTED TODAY...AND WITH
WARMER AIR OVER NEBRASKA AND IOWA BEING PULLED NORTHEASTWARD
TONIGHT INTO NORTHEAST IOWA/FAR SOUTHWEST WI...THOSE LOCATIONS
COULD SEE MORE RAIN THAN SNOW FOR MUCH OF TONIGHT. MISSISSIPPI
RIVER VALLEY LOCATIONS WOULD ALSO BE INCLUDED FOR A LITTLE MORE
RAIN. THIS IS DEPICTED NICELY IN LATEST RAP/HRRR DATA. THUS...SOME
OF THE SNOWFALL AMOUNTS HAVE BEEN REDUCED SLIGHTLY.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 256 PM CST SAT JAN 24 2015

MAIN FORECAST FOCUS IS ON LIGHT SNOW TONIGHT INTO SUNDAY MORNING.

A LIGHT RAIN/SNOW MIX IS OCCURRING ACROSS PORTIONS OF CENTRAL
NORTH DAKOTA THROUGH EASTERN SOUTH DAKOTA...TRACKING SOUTHEAST.
THIS ACTIVITY IS ASSOCIATED  WITH A SHORTWAVE PUSHING ACROSS
THESE AREAS WHICH IS EXPECTED TO TRACK SOUTHEAST INTO PORTIONS OF
THE UPPER MISSISSIPPI RIVER VALLEY LATE THIS EVENING INTO THE
OVERNIGHT HOURS. FORECAST MODELS HAVE LATCHED ONTO A MORE
SOUTHWEST SOLUTION COMPARED TO PREVIOUS RUNS TAKING THE BULK OF
THE ACCUMULATING SNOW ACROSS PORTIONS OF SOUTHEAST
MINNESOTA...NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE WAVE
DEEPENS AS IT MOVES INTO IOWA THIS EVENING PLACING AN ENHANCED
BAND OF SNOW ALONG THE NORTHERN EDGE OF THE DEEPENING SURFACE LOW.
18Z GUIDANCE IS TRICKLING IN AND IS SUGGESTING A SHIFT EVEN
FURTHER TO THE SOUTHWEST...WITH THE MAIN ACCUMULATING SNOW
OCCURRING SOUTH AND WEST OF THE HIGHWAY 52 CORRIDOR ACROSS
SOUTHEAST MINNESOTA/NORTHEAST IOWA. ANOTHER FEATURE TO KEEP AN EYE
ON THIS EVENING IS A WEAK SHORTWAVE/COLD FRONT DROPPING SOUTHWEST
OUT OF NORTHERN WISCONSIN. WE COULD SEE SOME LIGHT SNOW OUT OF
THIS FEATURE AS IT MOVES IN THIS EVENING. GIVEN THE SOUTHWARD
SHIFT AND SNOW ACCUMULATIONS MAINLY IN THE 1 TO 3 INCH
RANGE...WILL NOT BE ISSUING A WINTER WEATHER ADVISORY AT THIS
TIME. WEST CENTRAL INTO CENTRAL WISCONSIN SHOULD ONLY SEE LIGHT
ACCUMULATIONS...MAINLY IN THE TRACE TO 1 INCH RANGE.
ALSO...TEMPERATURES ARE PRETTY WARM LATE THIS AFTERNOON SO WE
COULD SEE A PERIOD OF LIGHT RAIN BEFORE THE PRECIPITATION SWITCHES
OVER TO SNOW. THE LOW EXITS THE REGION ON SUNDAY WITH SNOW ENDING.
ADDITIONAL ACCUMULATIONS OF 1/2 INCH TO AROUND 1 INCH ARE POSSIBLE
SOUTH OF INTERSTATE 90. PLAN ON SLIPPERY TRAVEL AT TIMES LATE
TONIGHT INTO SUNDAY MORNING.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 256 PM CST SAT JAN 24 2015

A WEAK FRONT MOVES ACROSS THE REGION SUNDAY NIGHT THOUGH MONDAY AN
MAY GENERATE SOME LIGHT SNOW WITH A SWITCH OVER TO FREEZING DRIZZLE
MONDAY AFTERNOON INTO MONDAY EVENING AS ICE IS LOST ALOFT.  A LIGHT
GLAZE OF ICE IS POSSIBLE IF THE FREEZING DRIZZLE DEVELOPS. RIDGING
SLIDES ACROSS THE AREA WEDNESDAY LEADING TO A RATHER PLEASANT DAY
FOR LATE JANUARY...WITH HIGHS CLIMBING WELL INTO THE 30S AND
POSSIBLY EVEN THE LOWER 40S ALONG AND WEST OF THE MISSISSIPPI RIVER.
A TROUGH THEN SWEEPS THROUGH WEDNESDAY NIGHT INTO THURSDAY BRINGING
A CHANCE OF SNOW TO THE REGION. TEMPERATURES LOOK TO COOL SLIGHTLY
FOR THE END OF THE WEEK WITH HIGHS SLIPPING INTO THE LOWER TO UPPER
20S. ANOTHER SYSTEM LOOKS TO MOVE THROUGH FRIDAY NIGHT INTO SATURDAY
BRINING SNOW CHANCES BACK INTO THE AREA. TEMPERATURES LOOK TO COOL A
LITTLE MORE BEHIND THIS SYSTEM WITH HIGHS FALLING INTO THE LOWER
TEENS TO LOWER 20S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1134 PM CST SAT JAN 24 2015

AN MVFR CEILING DEVELOPED EARLIER THIS EVENING IN A NARROW AREA
BETWEEN MSP AND RST...WHICH HAS STAYED GENERALLY IN PLACE.
MEANWHILE...MVFR CEILINGS ARE JUST LURKING OFF TO THE NORTHEAST OF
LSE. WITH A NORTHEAST FLOW DEVELOPING ASSOCIATED WITH LOW PRESSURE
TRACKING SOUTHEAST ACROSS IOWA...ANTICIPATING BOTH SITES TO BE IN
MVFR STRATUS BY 07Z. SNOW IS LIKELY TO DEVELOP AS WELL BETWEEN
07-09Z...ALLOWING THE CEILING AND VISIBILITY TO DROP TO IFR AT
RST. LSE SHOULD SEE VISIBILITIES DROP TO IFR AS WELL...BUT
ANTICIPATING CEILINGS TO STAY UP AT MVFR. SNOW LOOKS TO BEGIN
DIMINISHING AROUND 13Z...TOTALING UP TO LESS THAN 1 INCH. HOWEVER...A
LINGERING SURFACE TROUGH IN SOUTHEAST MN MAY ALLOW FOR A FEW HOURS
OF LIGHT FREEZING DRIZZLE TO PERSIST UNTIL 16Z. EXPECT WINDS TO
INCREASE TOO THIS MORNING UPWARDS OF 15 KT AT RST. DRIER AIR
COMING IN ON NORTHEAST WINDS LOOKS TO LIFT LSE TO VFR BY
18Z...WITH A SLOWER ARRIVAL TIME OF 00Z NOW AT RST BEING CLOSER TO
THAT OLD SURFACE TROUGH. VFR CONDITIONS WITH LIGHTER WINDS
ANTICIPATED FOR THE EVENING WITH HIGH PRESSURE MARCHING ACROSS THE
TAF SITES.

&&

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

$$

UPDATE...AJ
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...AJ


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