Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 272046
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
346 PM CDT FRI MAR 27 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 345 PM CDT FRI MAR 27 2015

AT 3 PM...A 1025 MB HIGH CENTERED OVER WEST CENTRAL WISCONSIN
KEPT SKIES SUNNY ACROSS THE UPPER MISSISSIPPI RIVER VALLEY.
DESPITE THE ABUNDANT SUNSHINE...THE COMBINATION OF COLD 925 MB
TEMPERATURES /-6 TO -10C/ AND STILL SOME SNOW COVER ACROSS
SOME PARTS OF THE REGION KEPT TEMPERATURES IN THE LOWER AND
MID 30S.

FOR TONIGHT...THE 27.12Z MODELS CONTINUE TO SHOW THAT A SHORT
WAVE TROUGH WILL MOVE QUICKLY SOUTHEAST THROUGH WESTERN MINNESOTA
AND WESTERN IOWA. SOUNDINGS CONTINUE TO SHOW MOISTURE LOCATED
BETWEEN 550 AND 450 MB MAINLY WEST OF THE MISSISSIPPI. THIS
MOISTURE IS CO-LOCATED WITH SOME WEAK OMEGA...SO THERE IS A
POSSIBILITY THAT SOME OF THE MID AND HIGH CLOUDS FROM THIS SYSTEM
MAY CREEP INTO THE AREAS WEST OF THE MISSISSIPPI RIVER DURING THE
EVENING AND EARLY OVERNIGHT. WITH MOSTLY CLEAR SKIES EXPECTED MUCH
OF THE OVERNIGHT AND LIGHT WINDS...IT WILL BE ANOTHER COLD NIGHT
ACROSS THE REGION. THE COLDEST TEMPERATURES /IN THE SINGLE
DIGITS/ WILL BE FOUND IN CENTRAL AND NORTH-CENTRAL WISCONSIN.
MEANWHILE THE REMAINDER OF THE AREA WILL HAVE LOW TEMPERATURES IN
THE TEENS.

ON SATURDAY...THE WINDS WILL BECOME SOUTHERLY AND INCREASE IN
SPEED AS THE HIGH PRESSURE AREA MOVES EAST AWAY FROM THE REGION
AND THE SURFACE PRESSURE GRADIENT INCREASES IN BETWEEN THE
DEPARTING HIGH AND APPROACHING SHORT WAVE FROM THE NORTHERN
PLAINS. THIS WILL BRING WARMER AIR INTO THE REGION. 925 MB
TEMPERATURES ON SATURDAY AFTERNOON WILL BE 2 TO 4C WARMER THAN
TODAY. THIS WILL ALLOW HIGH TEMPERATURES WILL CLIMB TO AROUND 40
DEGREES.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 345 PM CDT FRI MAR 27 2015

FROM LATE SATURDAY NIGHT INTO SUNDAY...THE 27.12Z MODELS CONTINUE
TO STRUGGLE WITH THE TIMING OF A SHORT WAVE TROUGH THROUGH THE
REGION. THE GFS CONTINUES TO BE THE FASTEST AT MOVING THIS SYSTEM
THROUGH THE AREA /BETWEEN 09Z AND 18Z/ AND THE ECMWF IS THE
SLOWEST /BETWEEN 12Z AND 21Z/. WITH MANY OF THE MESO MODELS
SUGGESTING NO PRECIPITATION UNTIL AFTER 09Z SUNDAY...DECIDED TO
SLOW THE ONSET OF PRECIPITATION UNTIL THEN. PRECIPITATION TYPE
STILL LOOKS UNCERTAIN. WITH THE AIR MASS VERY DRY AHEAD OF THIS
WAVE...EVAPORATIVE COOLING WILL BE AN ISSUE AS IT COOLS THE LAYER
BELOW FREEZING ALOFT. THIS AIR MASS THEN RECOVERS AS STRONG WARM
AIR ADVECTION BRINGS A LARGE LAYER OF WARM TEMPERATURES BACK INTO
THE AREA. OTHER ISSUES INCLUDE COLD SURFACE TEMPERATURES. DUE TO
THIS...STILL LOOKING AT A WINTRY MIX TRANSITIONING TO RAIN. BEFORE
THIS OCCURS...THERE MAY BE SOME LIGHT ACCUMULATIONS OF SNOW AND
ICE.

ON SUNDAY AFTERNOON...THE MODELS CONTINUE TO SHOW A TIGHT PRESSURE
GRADIENT AND STEEP LAPSE RATES BELOW 850 MB. THIS WILL ALLOW WIND
GUSTS TO CLIMB UP TO 40 MPH. WE WILL HAVE TO CONTINUE TO WATCH
THIS TIME PERIOD CLOSELY TO SEE WHETHER A WIND ADVISORY MAY BE
NEEDED.

ON MONDAY AFTERNOON AND NIGHT...THE MODELS CONTINUE TO DIFFER ON
WHETHER A SHORT WAVE TROUGH WILL BRING PRECIPITATION TO THE AREA.
FOR THE PAST 2 DAYS...THE GFS HAS KEPT THIS SYSTEM WELL NORTH OF
THE AREA. THE GEM HAS AN OPEN WAVE THAT PRODUCES PRECIPITATION
SOUTH OF INTERSTATE 94. FINALLY...THE ECMWF HAS A CLOSED LOW
MOVING THROUGH THE AREA. THIS SYSTEM BRINGS PRECIPITATION TO THE
ENTIRE AREA.

ON WEDNESDAY NIGHT...THE MODELS ARE COMING TO A CONSENSUS THAT A
COLD FRONT WILL MOVE THROUGH THE AREA DURING THE EVENING. MODEL
CONSENSUS FOR THIS DAY SUGGESTS HIGH TEMPERATURES RANGING FROM THE
MID 50S TO MID 60S. THIS MAY BE 10 TO 15 DEGREES TOO COLD
CONSIDERING THAT MANY OF THE MODELS HAVE 925 MB TEMPERATURES
WARMING TO NEAR 20C AND A PLENTY OF DRY AIR IS BEING BROUGHT INTO
REGION FROM THE PLAINS ALLOWING FOR PLENTY OF SUNSHINE AHEAD OF
THE FRONT. IN ADDITION TO TEMPERATURES BEING AN ISSUE...THERE WAS
SOME DISCUSSION THAT THUNDER MAY HAVE TO BE ADDED TO THE FORECAST.
THIS IS DUE TO 0-3 KM MOST UNSTABLE CAPES UP TO 1200 J/KG /MAY NOT
BE HIGH ENOUGH IF THE HIGHS ARE WARMER/. SINCE THE MODELS HAVE
BEEN STRUGGLING WITH THE TIMING OF THIS WAVE...THE CONSENSUS WAS
TO HOLD OFF AT THIS TIME.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1229 PM CDT FRI MAR 27 2015

SKIES WILL BE CLEAR THROUGH TOMORROW MORNING AS A RIDGE OF HIGH
PRESSURE MOVES THROUGH THE REGION. WINDS WILL BE LIGHT THROUGH THE
OVERNIGHT HOURS BEFORE PICKING UP OUT OF THE SOUTH TOMORROW
MORNING.


&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...HALBACH


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