Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 251721
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1221 PM CDT TUE AUG 25 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT TUE AUG 25 2015

AT 3 AM...EXTENSIVE CLOUDINESS WAS LOCATED FROM THE UPPER
MISSISSIPPI RIVER VALLEY EAST INTO THE GREAT LAKES. THESE CLOUDS
ARE ASSOCIATED WITH MOISTURE WRAPPING AROUND A CLOSED LOW LOCATED
JUST NORTH OF GEORGIAN BAY IN EASTERN ONTARIO. WITH A BLOCKING
HIGH LOCATED OVER NEWFOUNDLAND...THIS LOW HAS MOVED VERY LITTLE
SINCE SUNDAY. THE 25.00Z MODELS ARE IN GOOD AGREEMENT THAT THIS
LOW WILL SLOWLY FILL AND BECOME AN OPEN WAVE BY TONIGHT. WATER
VAPOR IMAGERY SHOWS THAT A SHORT WAVE TROUGH ROTATING AROUND ON
THE WESTERN PERIPHERY OF THIS SYSTEM /NORTH OF THE MINNESOTA
ARROWHEAD/ WILL MOVE SOUTH SOUTHEAST ACROSS WISCONSIN TODAY. THIS
SYSTEM WILL KEEP THE CLOUDS IN PLACE ACROSS WISCONSIN...AND THEN
SUBSIDENCE IN THE WAKE OF THIS SYSTEM WILL CAUSE SKIES TO
GRADUALLY CLEAR ACROSS WESTERN WISCONSIN TONIGHT.

MEANWHILE AS HEIGHTS RISE ACROSS MINNESOTA AND IOWA TODAY...DRY
AIR WILL GRADUALLY FILTRATE EAST INTO SOUTHEAST MINNESOTA AND
NORTHEAST IOWA. THIS WILL RESULT IN SOME GRADUAL CLEARING IN THESE
AREAS LATER THIS MORNING AND DURING THE AFTERNOON.

CLOUDS WILL CONTINUE TO KEEP HIGH TEMPERATURES IN THE 60S ACROSS
WESTERN WISCONSIN. MEANWHILE WITH 8 TO 10C 850 MB TEMPERATURES
WEST OF THE MISSISSIPPI RIVER...TEMPERATURES WILL ONLY WARM TO
NEAR 70 DEGREES.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 330 AM CDT TUE AUG 25 2015

FROM THURSDAY NIGHT INTO SATURDAY...THE 25.00Z MODELS ARE
CONTINUING TO SHOW THAT A SHORT WAVE TROUGH...THAT ORIGINATES IN
THE MONSOONAL FLOW CURRENTLY MOVING INTO THE BAJA PENINSULA...
WILL ROUND THE UPPER LEVEL RIDGE AND MOVE SOUTHEAST ACROSS
SOUTHWEST MINNESOTA...AND WESTERN AND SOUTHERN IOWA. THE NAM IS
THE STRONGEST AND FURTHEST NORTH WITH THIS SYSTEM. THIS IS LIKELY
DUE TO SOME CONVECTIVE FEED BACK. MEANWHILE THE GFS...GEM...AND
ECMWF HAVE THE SYSTEM A BIT FURTHER SOUTHWEST. REGARDLESS OF THE
TRACK...IT APPEARS THAT THIS WAVE WILL ENHANCE THE WARM AIR AND
MOISTURE ADVECTION INTO THE REGION. IN ADDITION...A SHORT WAVE
TROUGH MOVING ALONG THE POLAR JET ACROSS SOUTHERN CANADA WILL
BRING A FRONT WHICH WILL HELP FOCUS THE MOISTURE CONVERGENCE
ACROSS THE AREA. DUE TO THIS AND STILL A BIT OF UNCERTAINTY ON THE
TRACK OF THE SOUTHERN STREAM SYSTEM...OPTED TO JUST KEEP THE
PRECIPITATION CHANCES IN THE 30 TO 50 PERCENT RANGE FOR NOW. WITH
VERY MARGINAL MOST UNSTABLE CAPES...KEPT THUNDERSTORM CHANCES IN
THE 20 TO 40 PERCENT RANGE. WITH LITTLE INSTABILITY AND SHEAR...
NOT ANTICIPATING ANY SEVERE STORMS WITH THIS SYSTEM.

FOR THE UPCOMING WEEKEND AND EARLY NEXT WEEK...A STRONG SHORT
WAVE...CURRENTLY IN THE BERING SEA...WILL HELP CARVE OUT A TROUGH
ACROSS THE WEST COAST. THIS WILL HELP BUILD A RIDGE ACROSS THE
PLAINS AND UPPER MISSISSIPPI RIVER VALLEY. AS A RESULT...EXPECT TO
SEE A WARMING TREND DURING THIS TIME FRAME. BY MONDAY...HIGHS ARE
EXPECTED TO BE ABOVE NORMAL IN THE LOWER AND MID 80S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1220 PM CDT TUE AUG 25 2015

BACK EDGE OF STUBBORN MVFR STRATOCUMULUS CURRENTLY HUGGING THE
MISSISSIPPI RIVER...INCLUDING KLSE AND POINTS EAST. LOOK FOR THIS
FIELD OF STRATOCUMULUS TO ERODE EASTWARD THROUGH THE AFTERNOON
WITH KLSE SCATTERING OUT AROUND 20Z. BREEZY NORTHWEST WINDS WILL
SUBSIDE BY EVENING AS A RIDGE OF HIGH PRESSURE BUILDS INTO THE
AREA FROM THE NORTHERN PLAINS. THE RIDGE OF HIGH PRESSURE WILL
CONTINUE TO BUILD OVER THE AREA TONIGHT WITH DECENT DECOUPLING
EXPECTED IN THE MISSISSIPPI RIVER VALLEY LATE TONIGHT. AS A
RESULT...CONFIDENCE IS FAIRLY HIGH ON SOME FOG DEVELOPMENT ON THE
MISSISSIPPI CHANNEL GIVEN LIGHT/VARIABLE WINDS AND CLEAR SKIES
BUT LOW CONFIDENCE FOG WILL ACTUALLY SET UP AT KLSE. FOR
NOW...WENT WITH P6SM BCFG AT KLSE IN THE 10-14Z TIME FRAME AND
WILL LET THE EVENING FORECASTER ASSESS FURTHER. OTHERWISE...VFR
CONDITIONS EXPECTED UNDER THE RIDGE OF HIGH PRESSURE THROUGH
TOMORROW.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DAS



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