Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 141120
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
620 AM CDT SUN SEP 14 2014

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 325 AM CDT SUN SEP 14 2014

IR SATELLITE SHOWING INCREASING NE-SW BAND OF WARM AIR ADVECTION
CLOUD STRETCHING FROM NORTHERN WI THROUGH SOUTHERN MN. THIS WARM AIR
ADVECTION/CLOUD WAS IN RESPONSE TO A MID-LEVEL/SURFACE TROUGH MOVING
ACROSS THE NORTHERN PLAINS. TEMPERATURES ACROSS THE AREA EARLY THIS
MORNING RANGED FROM THE MIDDLE 30S ACROSS THE CRANBERRY/SAND COUNTRY
OF CENTRAL WI...TO THE LOWER AND MIDDLE 40S ELSEWHERE.

SURFACE LOW PRESSURE WILL MOVE ACROSS SOUTHERN CANADA WITH THE
NORTHERN PLAINS TROUGH PUSHING INTO/ACROSS NORTHERN WI AND UPPER
MISSISSIPPI RIVER VALLEY BY THIS AFTERNOON. MODELS KEEP BEST WARM
AIR ADVECTION/ISENTROPIC LIFT FORCING FOR SHOWER POTENTIAL CONFINED
ACROSS UPPER MI/FAR NORTHERN WI...OR JUST OUTSIDE OUR FORECAST AREA.
OTHERWISE...EXPECTING PARTLY SUNNY SKIES TODAY WITH HIGHS TOPPING
OFF IN THE 60S.

GENERAL/BROAD CYCLONIC FLOW ALOFT BRINGS ANOTHER MID-LEVEL TROUGH
INTO THE AREA TONIGHT. DYNAMICS A BIT BETTER WITH THIS WAVE SUCH AS:
RIGHT ENTRANCE REGION OF 300MB JET/FAIRLY STRONG 700-300MB PVA AND
MODERATE 700-500MB FRONTOGENESIS. THESE FORCING SIGNALS HAVE BECOME
INCREASINGLY CONSISTENT OVER THE LAST SEVERAL MODEL RUNS...SO KICKED
SHOWER CHANCES INTO CATEGORICAL RANGE BY LATE IN THE NIGHT. COULD
SEE SOME MODERATE RAINFALL AS WELL GIVEN THE STRENGTH/FOCUS OF THE
DYNAMICS. THINKING AREAS GENERALLY ALONG AND SOUTH OF I-90 COULD
PICK UP 1/4 TO 1/2 INCH BY MORNING. OTHERWISE...OVERNIGHT LOWS
EXPECTED TO BOTTOM OUT IN THE UPPER 30S ACROSS NORTH CENTRAL
WISCONSIN....AND IN THE 45-50 DEGREE RANGE SOUTH OF I-94.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 325 AM CDT SUN SEP 14 2014

TROUGH CONTINUES TO ROTATE SOUTHEAST THROUGH THE AREA MONDAY MORNING
FOR SHOWERS MAINLY ALONG AND SOUTH OF I-90. AS THE WAVE PULLS OFF IN
THE AFTERNOON AND HIGH PRESSURE BUILDS IN FROM THE NORTHERN
PLAINS...EXPECT THE SHOWERS TO EVENTUALLY PUSH OUT WITH DECREASING
CLOUDS ACROSS THE AREA FROM NORTHWEST TO SOUTHEAST. PLAN ON HIGHS IN
THE UPPER 50S TO THE LOWER 60S.

FOR MONDAY NIGHT....HIGH PRESSURE SETTLES INTO THE REGION FOR MOSTLY
CLEAR SKIES. THIS WILL SET UP IDEAL RADIATIONAL COOLING CONDITIONS
AND FOG POTENTIAL. THE RIDGE AXIS WILL STILL BE SLIGHTLY WEST OF THE
MISSISSIPPI RIVER REGION...SO COULD STILL BE ENOUGH LIGHT NORTHWEST
WIND TO MITIGATE FOG FORMATION. FOR NOW...CONFINED FOG MENTION TO
RIVER VALLEYS/TRIBUTARIES WHERE WIND DECOUPLING AND BETTER FOG
PRODUCTION SHOULD EXIST.

HIGH PRESSURE STRENGTHENS ACROSS THE REGION TUESDAY THROUGH THURSDAY
FOR A DRY STRETCH WITH A SLOW WARMING TREND. TEMPERATURES STILL LOOK
TO REMAIN SOME 5 TO 10 DEGREES BELOW NORMAL WITH HIGHS IN THE
60S...POSSIBLY PUSHING A FEW LOWER 70S BY THURSDAY.

SHOWER AND THUNDERSTORM CHANCES WILL BE SEEN FRIDAY INTO SATURDAY AS
THE RIDGE SLIPS EAST...ALLOWING A TROUGH TO APPROACH FROM THE
NORTHERN PLAINS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 620 AM CDT SUN SEP 14 2014

LOW PRESSURE SYSTEM MOVING ACROSS NORTHERN MN TOWARD SOUTHERN
ONTARIO. WARM ADVECTION VFR CLOUD BAND EXTENDS FROM SW-NE ACROSS
THE REGION AHEAD OF THE SYSTEM. AS SYSTEM MOVES INTO NORTHERN
GREAT LAKES TODAY...CLOUD BAND WILL SHIFT EAST. NEXT SHORT WAVE
TROUGH WILL QUICKLY MOVE IN FROM THE WEST TONIGHT. TRAILING FRONT
FROM THE FIRST SYSTEM WILL EXTEND FROM NORTHERN WI BACK INTO
NORTHWEST IA BY EVENING. ONCE AGAIN...WARM ADVECTION AND
FRONTOGENETIC FORCING WILL HELP FOCUS LIFT NEAR THE BOUNDARY.
EXPECT SUFFICIENT LIFT TO GENERATE HIGH BASED -RA/-SHRA FOR THE
EVENING AND OVERNIGHT HOURS. AT THIS TIME DO NOT ANTICIPATE
PRECIPITATION WILL BE QUITE HEAVY ENOUGH TO REDUCE VISIBILITY AND
CEILING BELOW VFR. BUT TREND HAS BEEN FOR A BIT STRONGER AND MORE
DYNAMIC SYSTEM SO THIS MAY NEED TO BE ALTERED.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION...MW


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