Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 260448
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1148 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 06Z TAFS THROUGH 06Z WEDNESDAY MORNING)
ISSUED AT 1148 PM CDT MON MAY 25 2015

MESSY SET OF TAFS THIS CYCLE WITH A COUPLE ROUNDS OF CONVECTION TO
MOVE ACROSS THE AREA...AND NOT THE CLEAREST OF SIGNALS AMONG THE
MODELS ON THE DETAILS. A WEAK SHORTWAVE WAS LIFTING NORTHEAST ACROSS
IA LATE THIS EVENING...PRODUCING SCT SHRA/TSRA THAT WERE LIFTING
TOWARD THE TAF SITES. BASED ON RADAR TRENDS...THIS TO IMPACT KLSE
MORE AND MAINLY PASS EAST OF KRST DURING THE EARLY OVERNIGHT HOURS.
AFTER THIS ROUND OF CONVECTION PASSES...GENERALLY GOOD VFR EXPECTED
IN THE 09Z-15Z PERIOD BEFORE THE NEXT STRONGER SHORTWAVE...ROUND OF
LIFT AND SHRA/TSRA SPREAD ACROSS THE TAF SITES. SHRA EXPECTED TO
MOVE INTO THE TAF SITES AFTER 15Z...THEN WITH AN INCREASE OF
INSTABILITY AND LIFT WITH THE SHORTWAVE SHRA/TSRA LOOK TO SPREAD
ACROSS THE TAF SITES THRU THE AFTERNOON. CIGS TO DROP INTO MVFR
RANGE AFTER 15Z WITH MVFR VSBYS IN HEAVIER SHRA/BR. LEFT TSRA
MENTION IN THE 18Z-23Z PERIOD AS VCTS/CB...GIVEN THE NUMEROUS SHRA
EXPECTED ACROSS THE AREA AND TSRA LOOKING TO BE SCT IN COVERAGE.
CIGS/VSBYS IN ANY TSRA WOULD DROP TO IFR. EVEN WITH PASSAGE OF THE
SFC-MID LEVEL LOW TUE AFTERNOON...PLENTY OF LOWER LEVEL MOISTURE/
MVFR CLOUDS WRAPPED AROUND THE SYSTEM LOOKING TO KEEP MVFR CIGS
ACROSS THE TAF SITES THRU TUE EVENING.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....RRS


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