Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 261314
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
814 AM CDT WED AUG 26 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT WED AUG 26 2015

AT 3 AM...THE WATER VAPOR IMAGERY SHOWS ANOTHER SHORT WAVE TROUGH
ON THE SOUTHWEST PERIPHERY OF THE CLOSED LOW SOUTH OF HUDSON
BAY WAS MOVING SOUTHEAST THROUGH NORTHEAST WISCONSIN. THIS LIKELY
HELPED WITH THE CLOUDS ADVANCING WEST INTO WEST CENTRAL AND
SOUTHWEST WISCONSIN OVERNIGHT. CURRENT TREND ON THE 11 TO 3.9
MICRON SATELLITE IMAGE SUGGEST THAT SKIES WILL BEGIN TO CLEAR THIS
MORNING. IT LOOKS LIKE THIS CLEARING WILL OCCUR AT LA CROSSE
WITHIN THE NEXT HOUR. AS THIS OCCURS...THERE IS STILL A
POSSIBILITY THAT MAYBE SOME PATCHY VALLEY MAY DEVELOP OR EVEN A
STRATUS DECK. WE ARE ALREADY NOTICING A MOISTURE LAYER DEVELOPING
OVER VALLEY THIS MORNING.

WITH FULL SUNSHINE TODAY...EXPECT THAT THE VALLEYS WILL WARM ABOUT
4F ABOVE THE NAM MOS AND WOULD MOST LIKELY BE NEAR OR A COUPLE OF
DEGREES WARMER THAN THE GFS MOS.

FOR LATE TONIGHT AND THURSDAY MORNING...THE MODELS CONTINUE TO
SHOW THAT THE LIGHT WINDS WILL EXTEND UP TO 7K FEET AND MOSTLY
CLEAR SKIES. THESE CONDITIONS WILL BE FAVORABLE FOR AREAS OF
VALLEY FOG TO DEVELOP.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 345 AM CDT WED AUG 26 2015

FROM THURSDAY NIGHT INTO SATURDAY...THE 26.00Z GFS AND ECMWF HAVE
TRENDED MORE TOWARD THE 25.00Z NAM SOLUTION. THESE 3 MODELS ARE
NOW IN AGREEMENT THAT A WELL DEVELOPED SHORT WAVE TROUGH AND
SURFACE LOW WILL TRACK EAST ACROSS THE FORECAST AREA. THIS TRACK
MAKES SENSE WITH A LONG WAVE TROUGH DEVELOPING ALONG THE WEST
COAST NORTH OF NORTHERN CALIFORNIA CAUSING THE RIDGE CURRENTLY
OVER THE ROCKIES TO SHIFT EAST WITH TIME AND UPPER LEVEL RIDGING
DEVELOPING ACROSS THE SOUTHEAST UNITED STATES AHEAD OF TROPICAL
STORM ERIKA. AT THIS TIME...THESE MODELS ARE IN GOOD AGREEMENT
THAT STRONG MOISTURE TRANSPORT WILL OCCUR NEAR THE INTERSTATE 90
CORRIDOR. WHILE PRECIPITABLE WATER VALUES WILL BE CLIMBING TO
AROUND 1.7 INCHES...THE WARM CLOUD LAYER DEPTH IS AROUND 3.5 KM
AND MOST UNSTABLE CAPES LESS THAN 500 J/KG ARE NOT AS FAVORABLE
FOR HEAVY RAIN. BOTH THE GFS AND NAM PRODUCE A 2 TO 4 INCH BAND OF
RAIN ALONG AND JUST NORTH OF INTERSTATE 90. MEANWHILE THE ECMWF
HAS 1 TO 2 INCHES OF RAIN IN THIS SAME AREA. CONSIDERING THE WARM
CLOUD LAYER DEPTHS AND INSTABILITY...LEANING MORE TOWARD THE
ECMWF RAINFALL TOTALS FOR THURSDAY NIGHT INTO FRIDAY NIGHT. EVEN
THOUGH FOLLOWED THE ECMWF RAIN TOTALS...WAS NOT AS CERTAIN WITH
IT HOLDING ONTO THE RAIN INTO SATURDAY EVENING...THUS OPTED TO
FOLLOW MORE THE GFS/NAM CONSENSUS WHICH HAS MUCH OF SATURDAY DRY.

FROM MONDAY INTO TUESDAY...A STRONG UPPER LEVEL RIDGE WILL BUILD
ACROSS THE AREA. BOTH THE GFS AND ECMWF ARE SHOWING 925 MB
TEMPERATURES CLIMBING INTO THE 26 TO 28C RANGE WHICH WOULD RESULT
IN TEMPERATURES IN THE LOWER 90S IN THE RIVER VALLEYS. THIS IS 3
TO 5 DEGREES WARMER THAN THE MODEL CONSENSUS. DUE TO THIS...OPTED
TO RAISE THE RIVER VALLEYS BY 2F WHICH RAISED THEM INTO THE UPPER
80S AND WILL CONTINUE TO MONITOR THIS TREND OVER THE NEXT COUPLE
OF DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 812 AM CDT WED AUG 26 2015

VALLEY FOG AT KLSE LOOKS LIKELY THURSDAY MORNING AS CLEAR
SKIES...LIGHT WINDS TO 6KFT...AND DRY AIR ABOVE THE SURFACE ARE
ALL IN PLACE. HAVE PLACED AN INTRODUCTION OF THE FOG AND FORECASTS
WILL TREND FROM THIS POINT DEPENDING ON THE LATEST OBSERVATIONS
AND GUIDANCE. OTHERWISE...VFR CONDITIONS.

&&

.HYDROLOGY...THURSDAY NIGHT INTO FRIDAY NIGHT
ISSUED AT 345 AM CDT WED AUG 26 2015

THE GFS...NAM...AND ECMWF ARE IN FAIRLY GOOD AGREEMENT THAT 1 TO
2 INCHES OF RAIN LOOKS POSSIBLE ALONG THE INTERSTATE 90 CORRIDOR
FROM THURSDAY NIGHT INTO FRIDAY NIGHT. ELSEWHERE RAINFALL AMOUNTS
LOOK TO BE LESS THAN AN INCH.

WITH HOURLY RAIN RATES LESS THAN AN INCH AN HOUR...NOT ANTICIPATING
ANY ISSUES WITH URBANIZED FLOODING. IN ADDITION...AREA RIVERS AND
STREAMS HAVE FLOWS CURRENTLY RUNNING ANYWHERE FROM 25 TO 50 PERCENT
OF CLIMATOLOGY. AS A RESULT...THIS RAIN SHOULD ONLY RESULT IN BANK
RISES.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...BAUMGARDT
HYDROLOGY...BOYNE



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