Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 031715
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1215 PM CDT TUE MAY 3 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT TUE MAY 3 2016

AT 3 AM...A COLD FRONT WAS LOCATED ACROSS SOUTHERN MANITOBA AND
SOUTHWEST ONTARIO. WITH LIMITED CAPE...VERY LITTLE PRECIPITATION
WAS FOUND ALONG THIS COLD FRONT. THE MESO MODELS ARE IN FAIRLY
GOOD AGREEMENT THAT THIS FRONT WILL MOVE INTO NORTH CENTRAL
WISCONSIN BY EARLY AFTERNOON. THIS FRONT WILL BE THEN LOCATED NEAR
INTERSTATE 90 BY LATE AFTERNOON AND BE EXITING NORTHEAST IOWA AND
SOUTHWEST WISCONSIN BY MID TO LATE EVENING. WITH SURFACE DEW
POINTS ONLY CLIMBING INTO THE MID 40S AHEAD OF THIS FRONT...THE
0-1 KM MEAN LAYER CAPES REMAIN CLOSE TO 500 J/KG. LIKE THE PAST
COUPLE OF DAYS...MUCH OF THE SHEAR REMAINS IN THE 0-3 KM RANGE AND
THE BEST MOISTURE CONVERGENCE IS LOCATED ALONG THE FRONT. AS A
RESULT...EXPECT THAT THE SHOWERS AND SCATTERED THUNDERSTORMS TO BE
PRIMARILY LINEAR ALONG THE COLD FRONT. WITH SOUNDINGS SHOWING AN
INVERTED V IN THE SUB CLOUD LAYER...THERE WILL GUSTY WINDS
ASSOCIATED WITH THESE SHOWERS AND STORMS.

IN ADDITION TO THE GUSTY WINDS ASSOCIATED WITH THE SHOWERS AND
STORMS...THERE WILL BE DEEP DIURNAL MIXING THIS AFTERNOON AND
EVENING. THIS WILL ALLOW THE STRONGER WINDS ALOFT TO MIX TO THE
SURFACE. THE RAP /WHICH SOMETIME HAS ISSUES WITH MIXING TOO DEEP/
HAS THE WIND GUSTS REACHING 40 MPH ACROSS PARTS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA. MEANWHILE THE GFS AND NAM...ONLY
HAVE THE WIND GUSTS REACHING 35 MPH IN THESE AREAS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 400 AM CDT TUE MAY 3 2016

ON WEDNESDAY NIGHT...THE 03.00Z MODELS CONTINUE TO SHOW THAT
TEMPERATURES WILL FALL INTO THE MID 30S ACROSS CENTRAL AND NORTH
CENTRAL WISCONSIN. WITH LIGHT WINDS AND MAINLY CLEAR SKIES...IT
CONTINUES TO LOOK LIKE THERE WILL BE A THREAT FOR SCATTERED
FROST.

ON FRIDAY...THE COMBINATION OF MOSTLY SUNNY SKIES...GUSTY
SOUTHWEST WINDS...COMPRESSIONAL HEATING...AND DEEP MIXING WILL
ALLOW TEMPERATURES TO WARM INTO THE LOWER AND MID 80S. THIS WAS 3
TO 5 DEGREES WARMER THAN THE MODEL BLEND HIGH TEMPERATURES FOR
THIS DAY. HOWEVER THEY DID FIT IN WELL WITH THE BIAS CORRECTED GFS
AND ECMWF GRIDS.

ON FRIDAY NIGHT...THE MODELS CONTINUE TO SHOW THAT A COLD FRONT
WILL MOVE SOUTH THROUGH THE AREA. WITH THE LOSS OF DIURNAL
HEATING...THE SURFACE AND MOST UNSTABLE CAPES ARE ONLY IN THE THE
500 TO 750 J/KG RANGE ALONG AND AHEAD OF THIS FRONT. WITH BOTH
THE 0-3 KM AND 0-6 KM SHEAR LESS THAN 20 KNOTS...NOT ANTICIPATING
ANY SEVERE WEATHER WITH ANY STORMS THAT HAPPEN TO DEVELOP.

FROM SATURDAY INTO SUNDAY...THE 03.00Z MODELS ARE BEGINNING TO
TREND DRY. THE GFS AND GEM EVEN KEEP THE AREA DRY ON SUNDAY NIGHT
AND MONDAY. MEANWHILE THE ECMWF HAS THE PRECIPITATION RETURNING ON
SUNDAY NIGHT AND MONDAY AS THE FRONT TO OUR SOUTH THIS WEEKEND
MOVES BACK TO THE NORTH AHEAD OF A LONG WAVE TROUGH IN THE CENTRAL
PLAINS. SINCE THIS IS A RELATIVELY NEW TREND...STAYED WITH WITH
CONSOLIDATED MODEL GRIDS FOR NOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1215 PM CDT TUE MAY 3 2016

A STRONG SHORTWAVE AND COLD FRONT ARE STILL SET TO MOVE SOUTH ACROSS
THE TAF SITES LATER THIS AFTERNOON/EARLY THIS EVENING. TIGHTER
GRADIENT/DEEPER DIURNAL MIXING AHEAD OF THE FRONT WILL PRODUCE WEST/
NORTHWEST WINDS 13-18KT G25-30KTS DURING THE EARLY/MID AFTERNOON
HOURS. FRONT AND LIFT FROM THE SHORTWAVE ARE EXPECTED TO PRODUCE A
BAND OF SHRA/SCT TSRA AS IT THEY MOVE SOUTH ACROSS THE AREA IN THE
ROUGHLY 21Z-02Z TIME-FRAME. TIMING ESTIMATE REMAINS 23-01Z THRU KRST
AND 00-02Z THRU KLSE. OUTSIDE OF ANY SHRA/TSRA...GOOD VFR EXPECTED
THRU THIS TAF PERIOD...AND MOVED SHRA AND ANY POTENTIAL CIG/VSBY
RESTRICTIONS WITH THEM TO A TEMPO MENTION AS THE FRONT PASSES.
ANY SHRA/TSRA LOOKING TO ONLY IMPACT THE KRST/KLSE AIRFIELDS FOR
1/2HR OR LESS. NORTHWEST WINDS AROUND 10KTS TO CONTINUE TONIGHT/
EARLY WED MORNING BEHIND THE FRONT. DIURNAL WARMING/MIXING BY LATE
WED MORNING TO RESULT IN AN INCREASE OF AND SOME GUSTINESS OF THE
NORTHWEST WINDS AFTER 04.15Z.

&&

.FIRE WEATHER...THROUGH THIS EVENING
ISSUED AT 400 AM CDT TUE MAY 3 2016

WEST WINDS OF 15 TO 25 MPH WITH GUSTS UP TO 40 MPH ARE POSSIBLE
THIS AFTERNOON AHEAD OF A COLD FRONT PUSHING SOUTHWARD THROUGH
THE REGION. IN ADDITION...AFTERNOON MINIMUM RELATIVE HUMIDITY
VALUES WILL FALL INTO THE 25 TO 35 PERCENT RANGE. THE LOWEST
RELATIVE HUMIDITY VALUES WILL BE IN CENTRAL WISCONSIN. WHILE THERE
WILL BE A LINE OF SHOWERS AND STORMS ALONG THE FRONT...THE RAIN
WILL LIKELY NOT BE WIDESPREAD. RAIN AMOUNTS WILL GENERALLY LESS
THAN 0.25 INCH. IN THE WAKE OF THIS FRONT...THE WIND WILL BECOME
NORTHERLY AND WIND SPEEDS WILL FALL BELOW 10 MPH.

&&

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

$$

SHORT TERM.....BOYNE
LONG TERM......BOYNE
AVIATION.......RRS
FIRE WEATHER...BOYNE


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