Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 052044
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
344 PM CDT TUE MAY 5 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 343 PM CDT TUE MAY 5 2015

AT 3 PM...LIGHT RAIN CONTINUES TO FALL ALONG AND SOUTH OF THE
INTERSTATE 90 CORRIDOR. HOURLY RAINFALL AMOUNTS ARE RANGING FROM
JUST A TRACE TO 0.05 INCHES PER HOUR. THIS RAIN IS BEING PRODUCED
BY 900 TO 800 MB FRONTOGENESIS AND A SURFACE WARM FRONT IN
NORTHERN IOWA. 05.12Z MODELS CONTINUE TO SHOW THAT THE WARM FRONT
WILL MOVE SLOWLY NORTH TO THE INTERSTATE 90 CORRIDOR TONIGHT AND
INTO CENTRAL MINNESOTA AND NORTHERN WISCONSIN ON WEDNESDAY. THIS
FRONTOGENESIS AND WARM FRONT WILL CONTINUE TO BE FOCUS OF RAIN.
WITH SOME DRIER AIR IN THE MID LEVELS MOVING INTO THE REGION
DURING IN THE WARM SECTOR OF THIS FRONT...THINKING THAT THIS AREA
COULD BE DRY MUCH OF WEDNESDAY. BOTH THE ARW AND NMM SUGGEST THIS
POSSIBILITY FOR MUCH OF THE DAY.

INSTABILITY LOOKS REALLY WEAK FROM TONIGHT INTO WEDNESDAY...BUT
WITH THE FRONT IN THE AREA AND 850 TO 700 MB LAPSE RATES IN THE 8
TO 10 C/KM RANGE...CANNOT COMPLETELY RULE OUT A THUNDERSTORM...SO
JUST KEPT AN ISOLATED STORM IN THE FORECAST.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 343 PM CDT TUE MAY 5 2015

FROM WEDNESDAY NIGHT INTO THURSDAY...THE 05.12Z MODELS CONTINUE TO
SHOW THAT THE AREA WILL BE LOCATED IN THE WARM SECTOR OF THE
SYSTEM. THERE CONTINUES TO BE MODERATE MOISTURE TRANSPORT INTO THE
AREA...BUT THE BEST CONVERGENCE REMAINS NORTH AND WEST OF THE
AREA SO THERE IS A POSSIBILITY THAT THIS PERIOD COULD BE DRY. THIS
IS ESPECIALLY THE CASE IN WESTERN WISCONSIN. AS A RESULT...KEPT
THE PRECIPITATION CHANCES THE LOWEST IN THESE AREAS.

ON THURSDAY NIGHT...THE COLD FRONT WILL MOVE EAST THROUGH THE
AREA. 0-1 KM MIXED LAYER CAPES CLIMB INTO THE 1 TO 2K RANGE AHEAD
OF THIS FRONT. LIKE THE PAST COUPLE OF DAYS...THE 0-6 KM SHEAR
REMAINS LESS THAN 30 KNOTS...SO NOT EXPECTING ANY SUPERCELLS.
HOWEVER WITH THE COLD FRONT PRODUCING LINEAR CONVECTION AND 0-3 KM
UP TO 40 KNOTS COULD NOT RULE SOME ISOLATED DAMAGING WIND.

FROM FRIDAY INTO SATURDAY...THE MODELS DIVERGE SOME. THE GFS
BUILDS A HIGH PRESSURE AREA INTO THE AREA. MEANWHILE THE GEM AND
ECMWF STALL THE FRONT TO OUR SOUTHEAST AND SEVERAL WAVES OF LOW
PRESSURE CONTINUE TO BRING ROUNDS PRECIPITATION INTO THE SOUTHEAST
PORTION OF THE FORECAST AREA. WITH QUITE A BIT OF UNCERTAINTY IN
THIS TIME FRAME...JUST STAYED WITH THE MODEL CONSENSUS.

FOR EARLY NEXT WEEK...THE GFS CONTINUES TO TRACK THE SURFACE LOW
TO OUR SOUTHEAST. MEANWHILE THE ECMWF HAS TRENDED A BIT FURTHER
NORTHEAST AND IT HAS PARTS OF SOUTHWEST WISCONSIN AND NORTHEAST
IOWA ENTERING THE WARM SECTOR OF THIS SYSTEM. DUE TO INCONSISTENT
SIGNALS IN THE TRACK AND EVEN TIMING...OPTED TO STAY WITH THE
MODELS CONSENSUS FOR NOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1230 PM CDT TUE MAY 5 2015

A WARM FRONT WAS LOCATED ACROSS CENTRAL IA AND NORTHERN IL AT MID=-
DAY...ROUGHLY NEAR I-80. NORTH OF THIS FRONT WAS A BROAD BAND OF
MVFR/IFR CIGS/VSBYS. A BAND OF LIGHT RAIN WAS EXITING THE TAF SITES
EARLY THIS AFTERNOON...BUT THIS RAIN GENERALLY HAVING LITTLE IMPACT
ON VSBYS. SFC-850MB FLOW WAS EAST TO SOUTHEAST ACROSS THE AREA. THIS
FLOW WILL BECOME MORE SOUTHERLY LATE THIS AFTERNOON/TONIGHT...
LIFTING THE FRONT NORTHWARD ACROSS THE AREA...AND SPREADING THE
LOWER CIGS/VSBYS ACROSS THE TAF SITES THIS AFTERNOON/TONIGHT.
TRENDED KRST/KLSE TAFS TOWARD MORE MVFR/IFR CIGS THIS AFTERNOON AND
ESPECIALLY TONIGHT AS THE FRONT LIFTS TOWARD/INTO THE AREA. ADDED
MVFR/IFR VSBYS IN BR LATER TONIGHT INTO EARLY WED MORNING AS WELL.
FRONT IS LOOKING TO LIFT NORTH OF I-90 BY 13Z WED...WITH GENERALLY
VFR CONDITIONS FOR WED MORNING ONCE THE FRONT LIFTS NORTH OF THE TAF
SITES. MAY BE SOME SCT -SHRA AROUND LATER TONIGHT/WED MORNING
WARRANTING A VCSH...BUT PROBABILITIES AND CONFIDENCE IN ANY OF THE
SHRA DETAILS AFTER 06Z ON THE LOWER SIDE AND LEFT THESE MENTIONS OUT
OF THE TAFS FOR NOW. WINDS MAINLY SOUTHEAST AROUND 10KTS THRU THE
PERIOD.


&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION.....RRS



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