Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 251140
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CST SUN JAN 25 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CST SUN JAN 25 2015

THE MAIN FOCUS IS ON THE DEPARTING SNOW THIS MORNING FOLLOWED BY
THE TEMPERATURE TRENDS TONIGHT.

CURRENTLY...AN OPEN MID LEVEL TROUGH IS PROPAGATING EAST ACROSS
IOWA WITH A SURFACE LOW ANALYZED NEAR DES MOINES. TRENDS CONTINUE
TO BE FOR THIS SYSTEM TO BE FURTHER SOUTH THAN PREVIOUSLY FORECAST
WHICH IS REDUCING THE SNOW AMOUNTS LOCALLY AND ALSO GOING TO MEAN
THAT THE PRECIPITATION SHOULD END SOONER AS WELL. THERE IS A
SMALL CHANCE THAT THE COLUMN LOSES ICE ALONG THE NORTHERN FRINGE
OF THE PRECIPITATION SHIELD BUT IT APPEARS THAT SUBSIDENT AND
DRIER AIR MOVES IN RATHER QUICKLY THROUGH THIS MORNING. STORM
TOTAL SNOW AMOUNTS LOOK TO BE RATHER MEAGER AT AN INCH OR LESS.

HIGH TEMPERATURES WILL BE MET FIRST THING THIS MORNING WITH COLDER
AIR MOVING DOWN FROM THE NORTHEAST THROUGHOUT THE DAY. A SURFACE RIDGE
OF HIGH PRESSURE WILL MOVE THROUGH THE REGION THIS EVENING WITH
RETURN SOUTHERLY LOW LEVEL FLOW KICKING IN OVERNIGHT. THIS SHOULD
LEAD TO A NON-DIURNAL TEMPERATURE TREND WITH LOW TEMPERATURES
OCCURRING IN THE EVENING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 331 AM CST SUN JAN 25 2015

THE NEXT ROUND OF PRECIPITATION LOOKS LIKE IT WILL COME IN EARLY
ON MONDAY AS A WEAK MID LEVEL SHORTWAVE TROUGH DIVES DOWN INTO THE
WESTERN GREAT LAKES THROUGH THE NORTHWEST FLOW ALOFT. PRECIPITATION
TYPE APPEARS TO BE THE MAIN QUESTION...PARTICULARLY WITH WHETHER
THERE WILL BE ICE IN THE COLUMN OR NOT. 25.00Z NAM/GFS SOUNDINGS
ARE SHOWING SOME DEEPER MOISTURE/LIFT FURTHER NORTHEAST TOWARD
THE SURFACE LOW. AFTER A BRIEF PERIOD OF SNOW IN THE MORNING...IT
APPEARS THAT THE COLUMN LOSES ICE YET KEEPS SOME STRONG LOW LEVEL
FORCING/MOISTURE IN PLACE AS THE WARM FRONT MOVES IN. PERHAPS THE
BIGGEST QUESTION IS WITH WHETHER THE MODELS ARE OVERDOING THE
AMOUNT OF LOW LEVEL RH/LIFT OR IF IT IS LEGIT...PARTICULARLY
ALONG/NEAR THE FRONT. WITH SURFACE TEMPERATURES STARTING OFF BELOW
FREEZING...THERE IS SOME CONCERN THAT SOME ICING COULD
OCCUR...PARTICULARLY IN THE LATE MORNING TO AFTERNOON HOURS.

MID TO UPPER LEVEL RIDGING WILL THEN MOVE IN WITH WARMER AIR BEING
ADVECTED IN FROM THE SOUTHWEST ON WEDNESDAY. STILL SOME QUESTIONS
ABOUT HOW WARM IT WILL BE AS GUIDANCE HAS TAKEN A BIT OF A STEP
DOWN ON TEMPERATURES...POSSIBLY DUE TO HOW MUCH CLOUD COVER THERE
WILL BE. ANOTHER QUICK MOVING MID LEVEL SHORT WAVE TROUGH IS
EXPECTED TO DROP DOWN INTO THE WESTERN GREAT LAKES REGION ON
WEDNESDAY NIGHT INTO THURSDAY WITH SNOW EXPECTED TO BE THE MAIN
PRECIPITATION TYPE OF THIS EVENT. BEYOND THIS...AM EXPECTING A BIT
OF A COOLING TREND GOING INTO NEXT WEEKEND AS A COLD LOW LEVEL AIR
MASS DROPS DOWN FROM CANADA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 540 AM CST SUN JAN 25 2015

SNOW THREAT HAS ALREADY EXITED THE TAF SITES EARLY THIS MORNING...
BUT AN MVFR/IFR STRATUS DECK HAS BEEN LEFT BEHIND. THIS TO GRADUALLY
LIFT AND SCATTER OUT AS DRIER SFC-850MB AIR SPREADS IN FROM THE
NORTHEAST...IN THE 15-18Z TIME-FRAME AT KLSE AND 18-21Z TIME-FRAME
AT KRST. GENERALLY GOOD VFR CONDITIONS THEN EXPECTED FROM LATE THIS
AFTERNOON THRU TONIGHT AS A WEAK RIDGE OF HIGH PRESSURE BUILDS
ACROSS THE UPPER MIDWEST AND MOISTURE IS MAINLY AT AND ABOVE 700MB.

NEXT TROUGH AND SHORTWAVE QUICKLY DROPS INTO THE AREA LATE TONIGHT/
MON MORNING...WITH INCREASING -SN/-FZDZ CHANCES AND MVFR CLOUD DECKS
SPREADING IN TOWARD DAYBREAK MON. -SN/-FZDZ CHANCES MON MAINLY
ALONG/EAST OF THE MS RIVER BUT MVFR CLOUD DECKS MON LOOKING TO
SPREAD WESTWARD ACROSS MUCH OF MN/IA.

&&

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

$$

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


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