Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 242048
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
348 PM CDT THU APR 24 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 348 PM CDT THU APR 24 2014

AT 3 PM...RAIN AND DRIZZLE CONTINUES TO EAST OF RED WING
MINNESOTA TO CHARLES CITY IOWA LINE. THE HEAVIEST RAIN WAS FOUND
EAST OF A MEDFORD TO LANCASTER WISCONSIN LINE. THE ARW...HRRR...
RAP...AND NMM ARE IN GOOD AGREEMENT THAT THE BACK EDGE OF THIS
RAIN WILL CONTINUE TO PROGRESS EAST ACROSS WESTERN WISCONSIN THIS
EVENING...AND CLEAR THE ENTIRE FORECAST AREA BY 25.09Z. THIS BACK
EDGE CORRESPONDS WELL TO THE BACK EDGE OF THE 900 TO 500 MB
FRONTOGENESIS. ADDITIONAL RAINFALL FROM THIS SYSTEM WILL BE LESS
THAN A QUARTER OF AN INCH.

BUFKIT SOUNDINGS ARE IN GOOD AGREEMENT THAT THE SUBSIDENCE IN THE
WAKE OF THE SHORT WAVE WILL BE STRONG ENOUGH TO SCOUR MUCH OF THE
LOW LEVEL MOISTURE OUT OF THE AREA. AS A RESULT...EXPECT CLEARING
SKIES MAINLY WEST OF THE MISSISSIPPI RIVER THIS EVENING...AND
SOUTH OF INTERSTATE 94 IN WESTERN WISCONSIN OVERNIGHT. WINDS OF
THE RIDGE TOPS AND HIGHER ELEVATIONS WILL RANGE FROM 10 TO 15
KNOTS OVERNIGHT. THIS WILL LIKELY PRECLUDE ANY FOG DEVELOPMENT.
HOWEVER IN THE RIVER VALLEYS...THE MODELS SUGGEST THAT THERE WILL
BE ENOUGH DECOUPLING THAT THE WINDS WILL DROP TO LESS THAN 5 KNOTS
IN THE BOUNDARY LAYER. THIS MAY RESULT IN AREAS OF FOG DEVELOPING.

ON FRIDAY...HIGH PRESSURE WILL BUILD ACROSS THE AREA. UNDER MOSTLY
TO PARTLY SUNNY SKIES...THE AREA WILL BE ABLE TO MIX UP TO 800 MB.
THIS WILL ALLOW TEMPERATURES TO WARM INTO THE MID AND UPPER 50S
NORTH OF INTERSTATE 94...AND INTO THE 60S ACROSS THE REMAINDER OF
THE FORECAST AREA.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 348 PM CDT THU APR 24 2014

ON FRIDAY...A SHORT WAVE TROUGH WILL MOVE QUICKLY EAST THROUGH THE
UPPER GREAT LAKES. AS THIS OCCURS...A COLD FRONT WILL QUICKLY MOVE
SOUTH AND SOUTHWEST THROUGH THE FORECAST AREA. SOUNDINGS SUGGEST
THAT THERE WILL ONLY BE SOME MOISTURE BETWEEN 800 AND 700 MB. IN
ADDITION...THERE IS LIMITED OMEGA IN THIS LAYER. AS A RESULT...
REMOVED THE PRECIPITATION CHANCES FROM SOUTHWEST WISCONSIN AND
KEPT THE REMAINDER OF THE AREA DRY.

FROM SATURDAY AFTERNOON INTO SUNDAY...THE 925 AND 850 MB MOISTURE
TRANSPORT GRADUALLY INCREASES ACROSS THE AREA. THIS IS IN RESPONSE
TO A DEEPENING LOW PRESSURE SYSTEM MOVING SLOWLY FROM THE FOUR
CORNERS AREA INTO THE CENTRAL PLAINS. OVERALL...THE BEST MOISTURE
TRANSPORT WILL REMAIN SOUTH AND WEST OF THE AREA FROM SATURDAY
AFTERNOON AND NIGHT...AND THEN INCREASE ACROSS SOUTHEAST
MINNESOTA...NORTHEAST IOWA...AND SOUTHWEST WISCONSIN. WITH THE NAM
HAVING SLIGHTLY MORE INSTABILITY THAN THE GFS AND ECMWF...IT
GENERATES PRECIPITATION AS SOON AS SATURDAY AFTERNOON. MEANWHILE
THE GFS/ECMWF/GEM MODELS DO NOT HAVE THE PRECIPITATION MOVING INTO
THE AREA UNTIL AFTER MIDNIGHT SATURDAY NIGHT. WITH THE NAM BEING A
BIT TOO HIGH IN ITS SURFACE DEW POINTS...TRENDED THE PRECIPITATION
FORECAST MORE TOWARD THE LATTER MODELS. DUE TO THE HIGHER DEW
POINTS...THE NAM HAS MUCH MORE INSTABILITY WEST OF THE MISSISSIPPI
RIVER THAN THE OTHER MODELS. IF THE NAM VERIFIED THERE WOULD BE
SOME CONCERN FOR SOME ISOLATED ELEVATED HAIL PRODUCING SUPER
CELLS. HOWEVER THE DEW POINTS MAKE MUCH MORE SENSE IN THE GFS AND
ECMWF...THEREFORE...THE SHEAR IS MUCH TOO STRONG FOR THE CAPE
WHICH IS AVAILABLE. AS A RESULT...NOT ANTICIPATING ANY SEVERE
WEATHER AT THIS TIME.

FROM SUNDAY NIGHT THROUGH THURSDAY...AN UPPER LEVEL LOW WILL MOVE
SLOWLY EAST FROM THE CENTRAL PLAINS INTO THE SOUTHERN GREAT LAKES.
OVERALL THE BEST INSTABILITY LOOKS TO BE MAINLY SOUTH OF THE
FORECAST AREA...AND THE BEST SHEAR IS NORTH OF THE FORECAST AREA.
AS A RESULT...NOT EXPECTING ANY SEVERE WEATHER. ALSO WITH
TIME...THE BEST MOISTURE TRANSPORT WILL BE PROGRESSIVELY MOVING
AWAY FROM THE FORECAST AREA. THIS WILL LIKELY LIMIT THE RAINFALL
ACROSS THE AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1231 PM CDT THU APR 24 2014

MAIN AVIATION CONCERNS ARE IFR/MVFR CONDITIONS AT BOTH RST AND
LSE TAF SITES THIS AFTERNOON INTO THIS EVENING AND FRIDAY MORNING.
LOW PRESSURE WILL CONTINUE TO PUSH INTO THE UPPER GREAT LAKES
REGION THIS EVENING. LATEST MOSAIC RADAR SHOWING MAINLY
SHOWERS/RAIN ACROSS NORTHEAST IOWA...SOUTHEAST MINNESOTA AND
WESTERN WISCONSIN. LATEST METARS ARE REPORTING CEILING HEIGHTS
UNDERNEATH THE SHIELD OF RAIN/SHOWERS IN THE MVFR TO VFR RANGE
ACROSS THE AREA. THE LATEST 24.12Z NAM/RAP BUFKIT SOUNDINGS
INDICATE IFR/MVFR CEILING CONDITIONS OVER WESTERN MINNESOTA WILL
ADVECT INTO RST/LSE TAF SITES THIS AFTERNOON INTO EARLY THIS
EVENING. HAVE INTRODUCED MVFR CONDITIONS IN THIS TIME FRAME AT
BOTH SITES AND INTRODUCED THE POSSIBILITY OF IFR CONDITIONS FROM
18 TO 21Z AT RST TAF SITE.

NEXT CONCERN IS POSSIBLE FOG POTENTIAL TONIGHT FRIDAY MORNING. DRIER
AIR FILTERS INTO THE REGION BEHIND SURFACE COLD FRONT AFTER 00Z
FRIDAY. VFR CONDITIONS WILL PREVAIL AT BOTH TAF SITES BY 05Z. THE
24.12Z GFS/NAM BUFKIT SOUNDINGS SHOW AN INVERSION DEVELOPING AFTER
06Z FRIDAY. WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS...AREAS
OF FOG AND POSSIBLY DENSE FOG COULD DEVELOP AT THE TAF SITES BY
09Z. AT THIS TIME...HAVE KEPT IN MVFR VISIBILITY CONDITIONS AT RST
AND LSE FROM 09Z TO 14Z.


&&

.HYDROLOGY...TONIGHT THROUGH THURSDAY
ISSUED AT 348 PM CDT THU APR 24 2014

SINCE WEDNESDAY...A HALF TO ONE AND A HALF INCHES OF RAIN HAS FALLEN
ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND WESTERN WISCONSIN.
THIS RAINFALL...IN ADDITION TO SOME MELTING SNOW UPSTREAM OF THE
AREA...WILL CAUSE WITHIN BANK RISES ON AREA RIVERS THIS WEEKEND.

ADDITIONAL...RAIN IS EXPECTED TO FALL FROM SATURDAY NIGHT THROUGH
THE MIDDLE OF NEXT WEEK.  RAINFALL TOTALS OF 1 TO 2 INCHES ARE
POSSIBLE DURING THIS TIME. THIS RAIN WILL CAUSE ADDITIONAL RISES ON
AREA RIVERS. IT IS UNCERTAIN AT THIS TIME WHETHER ANY FLOODING WILL
OCCUR.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DTJ
HYDROLOGY...BOYNE



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