Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 180825
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
325 AM CDT FRI APR 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 325 AM CDT FRI APR 18 2014

QUIET AND SEASONAL CONDITIONS ARE EXPECTED TODAY AS A SURFACE
RIDGE AXIS SHIFTS EASTWARD INTO THE GREAT LAKES. SOME FOG HAS
DEVELOPED THIS MORNING ACROSS PORTIONS OF NORTH CENTRAL
IOWA...SOUTH CENTRAL MINNESOTA ON UP TO NORTH CENTRAL WISCONSIN
IN RESPONSE TO IDEAL RADIATIONAL COOLING CONDITIONS. VISIBILITY
HAS DROPPED TO BETWEEN 1/4SM TO 2SM AT TIMES...SO WILL HAVE TO
WATCH FOR HOW WIDESPREAD THE FOG BECOMES AND WHETHER ANY DENSE FOG
FORMS. OTHERWISE...WINDS WILL GRADUALLY SHIFT AROUND TO THE EAST
SOUTHEAST AND BE ON THE INCREASE LATER IN THE AFTERNOON AND
EVENING AS THE RIDGE SHIFTS EAST AND THE NEXT SYSTEM REACHES THE
DAKOTAS. TEMPERATURES WILL CLIMB BACK UP TO JUST BELOW SEASONAL
NORMS WITH SOME HIGH LEVEL CLOUD COVER COMING IN AHEAD OF THIS
NEXT SYSTEM.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 325 AM CDT FRI APR 18 2014

THE MAIN FOCUS THROUGH EARLY NEXT WEEK IS ON A FRONT THAT STALLS
OUT ACROSS THE REGION AND PROVIDES SOME SHOTS FOR RAIN AND A FEW
THUNDERSTORMS. AS THE SURFACE LOW THAT CURRENTLY IS IN WYOMING
LIFTS UP INTO ONTARIO SATURDAY NIGHT...IT WILL DRAG A COLD FRONT
INTO THE REGION BEFORE STALLING IT OUT FROM CENTRAL IOWA INTO
SOUTHERN WISCONSIN. THIS AREA WILL BE THE FOCUS FOR RAIN TO
DEVELOP ALONG AS A WEAK MID LEVEL TROUGH COMES ACROSS THE PLAINS
AND DEEPER MID LEVEL TROUGHS TRACK ACROSS SOUTHERN CANADA.
INITIALLY THERE IS NOT MUCH FORCING ALONG THE FRONT SATURDAY NIGHT
INTO EARLY SUNDAY...BUT AS THE MID LEVEL TROUGHS APPROACH LATER ON
SUNDAY...THE FRONT GETS A LITTLE EXTRA SHOT OF LOW LEVEL MOISTURE
TRANSPORT ALONG WITH SOME WEAK INSTABILITY. THIS APPEARS TO BE THE
HIGHEST CHANCE FOR SEEING SOME RAIN OVER THE WEEKEND BEFORE THE
FRONT DRIFTS EAST ON MONDAY. SEVERE WEATHER IS NOT LOOKING LIKELY
AS THE DEEP SHEAR IS NON-EXISTENT AND 18.00Z NAM/GFS PROFILES
SHOW THAT THE MEAGER INSTABILITY THAT DOES DEVELOP IS SKINNY AND
ONLY A FEW HUNDRED J/KG INTO NORTHEAST IOWA.

AFTER A RIDGE MOVES THROUGH MID WEEK...A DEEPER TROUGH WILL MOVE
IN ON THURSDAY WITH ANOTHER ROUND OF CONVECTION POSSIBLE. LOW
LEVEL MOISTURE TRANSPORT LOOKS BETTER WITH THIS DEEPER TROUGH THAT
TAPS INTO THE GULF. THIS SHOULD LEAD TO SOME HIGHER CAPE AS WELL
WITH THUNDER A BIT MORE LIKELY.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1107 PM CDT THU APR 17 2014

THE STUBBORN STRATUS DECK HAS BEEN CLEARING THROUGH THE EVENING.
RST HAS ALREADY CLEARED AND LSE REMAINS ON TRACK TO CLEAR OUT
RIGHT AROUND 06Z. THIS CLEARING COMBINED WITH RELATIVELY HIGH
DEWPOINTS AND LIGHT WINDS SETS THE STAGE FOR BR FORMATION...
ALREADY OCCURRING OVER SOUTH CENTRAL MN. HAVE INCLUDED POTENTIAL
MVFR VISIBILITIES AT BOTH TAF SITES FROM 07-12Z. ANY BR SHOULD BE
VERY THIN AND DISSIPATE QUICKLY WITH SUNRISE. VFR CONDITIONS LOOK
TO PREVAIL THEREAFTER WITH ONLY SOME PERIODS OF ALTOSTRATUS
CROSSING THE TAF SITES DURING THE DAYTIME HOURS.

THE LIGHT WINDS WILL PICK UP OUT OF THE EAST DURING THE DAY...THEN
VEER SOUTHEASTERLY THIS EVENING. LOOKING AT TOP SPEEDS IN THE 8-13
KT RANGE FOR THIS EVENING. THERE ARE INDICATIONS OF LOW LEVEL
WIND SHEAR DEVELOPING AT RST TOWARDS 05Z...BUT SPEEDS ARE MARGINAL
AT 40 KT AT 2000 FT. GIVEN THIS MARGINALITY AND BEING AT THE END
OF THE TAF PERIOD HAVE DECLINED TO MENTION IT IN THE TAF.


&&

.HYDROLOGY...
ISSUED AT 325 AM CDT FRI APR 18 2014

RECENT RAINFALL AND SNOWMELT IS KEEPING RIVER LEVELS ELEVATED
ACROSS THE REGION...PARTICULARLY ALONG THE MISSISSIPPI RIVER. A
FRONT IS EXPECTED TO SLOWLY MOVE ACROSS THE REGION AND STALL OUT
SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH PERIODS OF RAIN EXPECTED
OVER THIS TIME FRAME. CURRENT PROJECTIONS SAY THAT A HALF INCH TO
AN INCH OF RAIN IS POSSIBLE...PARTICULARLY IN AN AREAS WHERE RAIN
TRAINS OVER THE SAME SPOT.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
HYDROLOGY...HALBACH



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