Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 181725
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1225 PM 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 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1225 PM CDT FRI APR 18 2014

HIGH PRESSURE WILL DRIFT EAST OF THE AREA THIS AFTERNOON...WHILE A
COLD FRONT MOVES ACROSS THE DAKOTAS AND INTO WESTERN MN BY SAT
MORNING. GENERALLY DRY LOW/MID LEVEL AIR WILL REMAIN OVER THE TAF
SITES THIS AFTERNOON THRU SAT...WITH GOOD VFR CONDITIONS EXPECTED.

THE PRESSURE GRADIENT OVER THE AREA WILL TIGHTEN TONIGHT AND SAT.
LIGHTER GENERALLY EAST WINDS THIS AFTERNOON WILL GRADUALLY INCREASE
TONIGHT AND BECOME SOUTHEAST. THESE WINDS WILL KEEP THE BOUNDARY
LAYER STIRRED AND ANY LATE NIGHT/EARLY MORNING HZ/BR TO A MINIMUM.
WITH DIURNAL WARMING/MIXING...WINDS WILL INCREASE THRU SAT
MORNING...BECOMING SOUTH AT 15-20KTS G25-30KTS THRU SAT MORNING AND
FOR SAT AFTERNOON.

&&

.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.....RRS
HYDROLOGY....HALBACH



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