Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 301948
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
248 PM CDT SUN AUG 30 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 248 PM CDT SUN AUG 30 2015

VISIBLE SATELLITE EARLY THIS AFTERNOON SHOWS THE LOW CLOUDS OVER
THE AREA ARE BREAKING UP/CLEARING OUT MUCH QUICKER THAN WHAT
OCCURRED SATURDAY AFTERNOON. WITH THESE TRENDS...EXPECT THAT MOST
IF NOT ALL OF THE AREA WILL BECOME MOSTLY CLEAR THIS EVENING. THE
CONCERN THEN BECOMES WHETHER ANY FOG OR LOW CLOUDS WILL FORM AGAIN
OVERNIGHT. THE 30.12Z NAM FORECAST SOUNDINGS AGAIN SHOW SATURATION
OCCURRING AT THE SURFACE FOR THE VALLEY SITES. HOWEVER...THE WINDS
JUST ABOVE THE SURFACE ARE EXPECTED TO BE BLOWING PRETTY GOOD WITH
THE NAM SHOWING BETWEEN 20 AND 25 KNOTS AROUND 1500 FEET. THIS
SHOULD TEND TO KEEP THE FOG FROM FORMING BUT LEAD TO ANOTHER LOW
CLOUD DECK. NOT SURE HOW EXPANSIVE THE CLOUD DECK WILL BE SO FOR
NOW WILL INCREASE THE CLOUDS INTO THE 40 TO 50 PERCENT RANGE AND
LET THE EVENING SHIFT ADJUST AS NEEDED.

DAYTIME TEMPERATURES STILL LOOK LIKE THEY WILL BE ABOVE NORMAL TO
START THE WEEK. THE LOW LEVEL RIDGE AXIS WILL SLIP INTO THE OHIO
RIVER VALLEY WHICH WILL SET UP A SOUTHWEST FLOW OVER THE REGION.
925 MB TEMPERATURES ARE EXPECTED TO WARM TO AROUND 25C MONDAY AND
THEN COULD REACH THE 27C TO 29C RANGE TUESDAY. AT THE
SURFACE...HIGHS MONDAY SHOULD RANGE FROM THE LOWER TO MIDDLE 80S
WITH SOME UPPER 80S POSSIBLE IN THE VALLEYS AND LOOK FOR MIDDLE TO
UPPER 80S TUESDAY WITH LOWER 90S IN THE VALLEYS.

THERE LOOKS TO BE A SMALL THREAT FOR SOME RAIN TUESDAY NIGHT. A
WEAK SHORT WAVE TROUGH IS FORECAST TO COME ACROSS THE REGION...BUT
THE 30.12Z GFS SHOWS VERY LITTLE HEIGHT FALLS WITH THIS FEATURE.
A DISSIPATING SURFACE TROUGH SHOULD DRIFT INTO THE WESTERN PARTS
OF THE FORECAST AREA WITH SOME WEAK MOISTURE TRANSPORT OCCURRING
INTO THIS BOUNDARY AHEAD OF THE SHORT WAVE TROUGH. FORECAST
SOUNDINGS FOR KRST FROM THE GFS DO NOT INDICATE MUCH MOISTURE IN
THE COLUMN AND WHAT IS THERE IS ABOVE 10000 FEET. WILL CARRY JUST
A VERY SMALL CHANCE FOR SOME RAIN ACROSS THE WESTERN SECTIONS
FOR LATE TUESDAY NIGHT.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN AUG 30 2015

VERY LITTLE PATTERN CHANGE IS EXPECTED TO OCCUR THROUGH THE UP
COMING WEEKEND. THE UPPER LEVEL RIDGE IS EXPECTED TO REMAIN
ANCHORED FROM THE LOWER MISSISSIPPI RIVER VALLEY THROUGH THE OHIO
RIVER VALLEY INTO THE NORTHEAST PART OF THE COUNTRY. THE LONG WAVE
TROUGH WILL TRY TO MOVE SLOWLY EAST FROM THE PACIFIC COAST INTO
THE CANADIAN ROCKIES AND PACIFIC NORTHWEST. THIS WILL MAINTAIN THE
SOUTHWEST FLOW ALOFT OVER THE UPPER MIDWEST WITH THE POSSIBILITY
OF SHORT WAVE TROUGHS COMING OUT OF THE LONG WAVE TROUGH AND
ACROSS THE REGION. THIS FAR OUT IN TIME...IT WILL BE EXTREMELY
DIFFICULT TO TIME ANY OF THESE WEAK WAVES SO WILL STICK WITH THE
MODEL CONSENSUS GRIDS AND SHOW SOME LOW RAIN CHANCES EACH DAY.
SOME HINTS THAT THERE COULD BE A BETTER CHANCE OF RAIN FOR THE UP
COMING WEEKEND IF A SURFACE BOUNDARY CAN WORK INTO THE AREA LIKE
THE GFS IS TRYING TO SHOW...BUT THE 30.12Z ECMWF SUGGESTS THIS
BOUNDARY COULD STAY TO THE WEST OF THE AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1227 PM CDT SUN AUG 30 2015

MVFR STRATO-CU REMAIN PROBLEMATIC EARLY THIS AFTERNOON. HOWEVER...
VIS IMAGERY SHOWED THE LOWER CLOUD DECK WAS ERODING WITH DIURNAL
WARMING/MIXING AND INCREASING SOUTHWEST FLOW IN THE SFC-900MB LAYER.
APPEARS DECK WILL BREAK UP AT KRST AROUND 19Z AND AROUND 20Z AT
KLSE. GOOD VFR EXPECTED FOR THE LATE AFTERNOON AND EVENING
HOURS...BEING AIDED BY MORE SOUTHWEST WIND IN THE SFC-900MB LAYER
FOR STIRRING/MIXING. STILL A SIGNAL FOR SOME INCREASE OF 925MB
MOISTURE TO SPREAD NORTHEAST ACROSS IA TONIGHT...WITH LOWER CLOUDS
RETURNING FOR LATER TONIGHT. THE MOISTURE APPEARS QUITE SHALLOW AND
WITH AROUND 25KTS OF WIND JUST ABOVE THE NOCTURNAL INVERSION THERE
MAY BE TOO MUCH FLOW FOR A SOLID CLOUD DECK WITH THE SHALLOW/THIN
MOISTURE LAYER. LEFT CLOUDS LATE TONIGHT AS A SCT005 LAYER. WILL
HAVE TO WATCH TO OUR SOUTH ACROSS IA LATER TONIGHT IF THERE MAY BE A
MORE SOLID LOW CLOUD DECK ADVECTING NORTHEAST. THE WINDS JUST ABOVE
THE INVERSION LAYER TO HELP KEEP LATE NIGHT/EARLY MORNING BR/FG TO A
MINIMUM AS WELL. DIURNAL WARMING/MIXING EXPECTED TO RESULT IN SCT
CUMULUS ON MONDAY.


&&

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

$$

SHORT TERM...04
LONG TERM...04
AVIATION.....RRS



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