Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 250830
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
330 AM 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 NEW FOUNDLAND...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 SATUTRDAY...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 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1133 PM CDT MON AUG 24 2015

WILL BE DEALING WITH CONTINUED HIGHER BASED AND THIN STRATUS DECK AS
IT ROTATES AROUND LARGE UPPER LOW OVER SOUTHERN ONTARIO. ALTHOUGH
VFR THROUGHOUT...TYPICAL CHALLENGE IS TRYING TO TIME EVENTUAL
CLEARING. BACK EDGE IS VERY PERSISTENT AND CONSISTENT THIS
EVENING... AND WITH SHORT TERM GUIDANCE SUGGESTING ANOTHER MINOR
WAVE AROUND BACKSIDE OF LOW BRINGING REINFORCEMENT OF CLOUDS...
HAVE SLOWED DOWN CLEARING TREND EVEN MORE.

AFTER 25.18Z THOUGH...PRETTY GOOD SIGNAL FOR MOISTURE TO RETREAT
EAST SO EXPECT CLEARING TO WORK IN BY TUESDAY EVENING AS WINDS
CONTINUE TO DIMINISH AS WELL.

GRADIENT WILL HAVE TO BE WATCHED LOOKING AHEAD TO WEDNESDAY MORNING
FOR VALLEY FOG GIVEN LIGHTER WINDS.


&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...SHEA



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