Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 251943
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
240 PM CDT MON MAY 25 2015

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 240 PM CDT MON MAY 25 2015

THE MORNING ROUND OF THE MEMORIAL HOLIDAY PCPN HAS EXITED NORTH OF
THE FORECAST...BUT LIKELY WON/T BE THE LAST OF THE SHOWERS/STORMS
FOR TODAY/TONIGHT.

A WARM FRONT IS WAVERING ACROSS THE REGION...ROUGHLY FROM CENTRAL
WISCONSIN WEST-SOUTHWEST INTO SOUTHERN MINNESOTA. WITH SUN BREAKING
THROUGH THE CLOUDS IN THE SOUTH...INSTABILITY IS ON THE CLIMB. RAP
SUGGESTS UPWARDS OF 1000 J/KG OF MUCAPE SOUTH OF THE BOUNDARY BY
00Z. SHEAR IS DECENT ALONG THE FRONT...30-35 KTS 0-6 KM...BULK OF
WHICH IS IN THE 0-3 KM LAYER. MESO MODELS PERCOLATE ALONG THE
BOUNDARY BY LATE THIS AFTERNOON...PERSISTING INTO THE EVENING HOURS.
SEE SOME POTENTIAL FOR STRONGER TO EVEN SEVERE STORMS AROUND THE
FRONT...MORE SO THE FARTHER WEST YOU GO. ITS A PRETTY SMALL
THREAT...BUT WILL HAVE TO BE WATCHED. ANYTHING ON THE FRONT WOULD
POSE THE HIGHEST THREAT. MEANWHILE THE NAM AND HOPWRF SUGGEST A
PIECE OF UPPER LEVEL ENERGY SWINGS INTO IOWA THIS EVENING...WHICH
COULD SPARK A FEW SHOWERS/STORMS THERE...WHICH COULD THEN TRACK
ACROSS PARTS OF NORTHEAST IA/SOUTHWEST WI. CURRENTLY - RADAR IMAGERY
POINTS TO A SMALL CLUSTER OF SHOWERS/STORMS HEADED NORTHEAST ACROSS
NORTHEAST IA...CAPTURED WELL IN THE LATEST ARW. THIS IS EXPECTED TO
STREAK ACROSS THE FORECAST AREA...EXITING BY 00Z.

THE WARM FRONT IS STILL HANGING AROUND ON TUE AS UPPER LEVEL
TROUGHING SWINGS OVER THE UPPER MISSISSIPPI RIVER VALLEY. MODELS
DEPICT AN INITIAL BIT OF ENERGY AHEAD OF THE MAIN SHORTWAVE. THE
FIRST PIECE COULD STAY SOUTH OF THE AREA...BUT THE TROUGH LOOKS TO
TRACK THROUGH. SHOULD SEE MORE AREAS OF SHOWERS/STORMS ON TUE AS A
RESULT...WITH THE AFTERNOON THE MORE FAVORED AT THIS TIME. MUDDLED
SKY COVER PROMISES TO KEEP INSTABILITY IN CHECK SOMEWHAT...WITH
PERHAPS 1000 J/KG OF MUCAPE BY 00Z WED. BETTER SHEAR IS EAST/SOUTH
OF THE LOCAL AREA. DEPENDING ON HOW MUCH SUNSHINE CAN BE
REALIZED...A FEW STRONGER STORMS LOOK POSSIBLE TUE AFTERNOON/EARLY
EVENING.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 240 PM CDT MON MAY 25 2015

GFS/ECMWF REMAIN IN GOOD AGREEMENT WITH HOLDING ONTO THE FAIRLY
QUICK MOVING ZONAL FLOW INTO THE UPCOMING WEEKEND. WEDNESDAY STILL
SHAPING UP TO BE THE DRY DAY FOR THE WORK WEEK WITH SHORTWAVE
RIDGING AS A WEAK SFC HIGH SLIDING ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY.

AN UPPER LEVEL TROUGH CENTERED MOSTLY ACROSS CANADA IS EXPECTED TO
SWEEP WEST-EAST...KEEPING THE BULK OF ITS UPPER LEVEL ENERGY TO THE
NORTH. HOWEVER...IT WILL SWEEP A COLD FRONT THROUGH THE REGION THU
NIGHT-FRI NIGHT. SOME LOW LEVEL MOISTURE TRANSPORT WILL LEAD THE
FRONT IN...AND SOME INDICATIONS OF 1000 J/KG OR SO OF SBCAPE ON
FRIDAY. SHEAR WEAK TO MARGINAL AT THIS TIME. ENTIRELY TOO EARLY TO
HAVE CONFIDENCE IN ANY STRONG/SEVERE STORM THREAT - BUT IT IS A TIME
FRAME OF INTEREST AND WILL NEED TO BE MONITORED. GFS/EC ALSO IN
BETTER AGREEMENT THIS GO AROUND WITH PLACEMENT AND TIMING OF THE
VARIOUS WEATHER FEATURES.

FOR THE WEEKEND...THE EC IS CURRENTLY FAVORING HIGH PRESSURE WITH
THE COLD FRONT CONTINUING ITS SAG SOUTH. THE GFS IS SIMILAR...BUT
WOULD TOSS BITS OF ENERGY OUT OF AN UPPER LEVEL LOW OVER THE
SOUTHERN PLAINS INTO THE REGION. RAIN COULD RESULT. CONFIDENCE LOWER
IN THIS PERIOD AND WILL LET CONSENSUS SHAPE THE FORECAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1240 PM CDT MON MAY 25 2015

CHALLENGING TAF FORECAST GIVEN SHOWER/THUNDERSTORM CHANCES AND
ASSOCIATED CEILINGS/VISIBILITY. MULTIPLE UPDATES ARE LIKELY OVER THE
NEXT 24 HOURS.

CONCERNING PRECIPITATION...THERE IS A SMALL CLUSTER OF SHOWERS AND
AN ISOLATED LIGHTNING STRIKE OR TWO ACROSS NORTH-CENTRAL IA...
MOVING TO THE NORTHEAST AT 25 KTS. HOWEVER...CHANCES INCREASE FOR
GREATER SHOWER/THUNDERSTORM COVERAGE LATE THIS AFTERNOON AND EVENING
ALONG A SOUTHWEST TO NORTHEAST ORIENTED BOUNDARY ACROSS PORTIONS OF
THE UPPER MISSISSIPPI RIVER VALLEY. ALL SAID... CONFIDENCE IS LOW
THAT SHOWERS/THUNDERSTORMS WILL DIRECTLY IMPACT TAF AIRFIELDS AND
WILL COVER THREAT WITH VCSH FOR NOW.

MVFR/LOW VFR CEILINGS TO PERSIST THIS AFTERNOON/EVENING WITH HOURLY
OBSERVATIONS SOMETIMES BOUNCY BETWEEN CRITICAL THRESHOLDS (3000 FT
AGL AND 2000 FT AGL). MVFR CEILINGS TO DOMINATE OVERNIGHT AS LARGE
CLOUD MASS ACROSS MN/NORTHERN WI DRIFTS SOUTHWARD. SOUTH-SOUTHWEST
WINDS WILL PERSIST THROUGH THE PERIOD...GUSTING AS HIGH AS 25 KTS AT
TIMES THIS AFTERNOON.


&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....ROGERS


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