Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 051130
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
630 AM CDT SAT SEP 5 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM CDT SAT SEP 5 2015

FORECAST FOCUS IS ON RAIN CHANCES TODAY WITH WEAK DISTURBANCE
MOVING THROUGH THE REGION. AMOUNT OF CLOUD COVER AND RESULTING
TEMPERATURES THEN ON THE FOREFRONT.

REGIONAL RADAR LOOPS SHOW NARROW BAND OF SHOWERS MOVING SLOWLY
EAST THROUGH THE FORECAST AREA...LOCATED RIGHT ALONG THE
MISSISSIPPI RIVER AT 07Z. THIS OCCURRING IN A FAVORABLE
THERMODYNAMIC FORCING RIBBON. THIS EXPECTED TO TRANSLATE EAST
AND WEAKEN WITH TIME THIS MORNING. ONCE THIS AREA MOVES OFF...
HAZY SUNSHINE AND HUMID CONDITIONS WILL ONCE AGAIN PREVAIL SIMILAR
TO THE PAST FEW DAYS. MODELS ALL POINT TO ANOTHER WEAK SHORT WAVE
TROUGH MOVING NORTHEAST UP THE RIDGE AND INTO WESTERN MN BY
EVENING. THIS SHOULD HELP FIRE CONVECTION TO THE WEST OF THE
FORECAST AREA...AND SOME OF THIS COULD TRY AND SNEAK IN TO THE
WESTERN FRINGES OF OUR FORECAST AREA OVERNIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 250 AM CDT SAT SEP 5 2015

A PATTERN SHIFT WILL TAKE PLACE AS THE UPPER RIDGE SHIFTS EAST AND
FLATTENS IN RESPONSE TO THE LARGER WESTERN LONG WAVE TROUGH
OPENING AND EJECTING NORTHEAST INTO SOUTHERN CANADA BY SUNDAY. AS
THE FORCING FROM THE MAIN WAVE PASSES...IT SENDS A COLD FRONT
THROUGH THE LOCAL AREA LATE SUNDAY. WARM AIR AND DEEP MIXING AHEAD
OF THE FRONT WILL KEEP TEMPERATURES AND HEAT INDEX VALUES UP FOR
ONE LAST DAY. CAPE IS EXPECTED TO RISE TO 1500-2000 J/KG BUT SHEAR
WILL BE LIMITED...LAGGING THE FRONTAL PASSAGE. SOME STRONG STORMS
ARE POSSIBLE BUT NOT VERY CONFIDENT IN ANY SIGNIFICANT SEVERE
POTENTIAL. RAIN WILL END AND MUCH MORE SEPTEMBER-LIKE TEMPERATURES
ANTICIPATED BEHIND THE FRONT NEXT WEEK. AS UPPER FLOW BECOMES
ZONAL TO SLIGHTLY NORTHWEST...SOME WEAK RIPPLES WILL BE
TRANSITIONING THROUGH THE AREA. ONE SUCH DISTURBANCE MAY BRING
RAIN MONDAY NIGHT AND TUESDAY...WITH ANOTHER WEDNESDAY NIGHT INTO
THURSDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 630 AM CDT SAT SEP 5 2015

ISOLATED/SCT -SHRA AROUND KLSE WILL CONTINUE TO WEAKEN/MOVE EAST
EARLY THIS MORNING. CONVECTION WELL WEST OF KRST WAS LIFTING NORTH-
NORTHEAST...WITH ALL MODELS SHOWING THIS TO WEAKEN/END THRU THE
MORNING THUS LEFT ANY TSRA/SHRA MENTION OUT OF KRST TAF THIS
MORNING. GOOD VFR CONDITION THEN EXPECTED FROM MID MORNING THRU
TONIGHT AS MAIN FORCING/LIFT FOR CONVECTION IS MAINLY WEST OR WELL
NORTH OF THE AREA. PRESSURE GRADIENT OVER THE AREA CONTINUES TO
SLOWLY TIGHTEN AS LOW PRESSURE OVER WESTERN SD EARLY THIS MORNING
LIFTS INTO EASTERN ND BY 12Z SUN. SOUTH WINDS GUSTING AROUND 20KTS
EXPECTED AT KRST THIS AFTERNOON. SOUTH WINDS EXPECTED TO REMAIN 8-
12KTS TONIGHT. THIS BOUNDARY LAYER STIRRING PLUS A BKN CLOUD DECK
AROUND 15K FT AFTER 06Z SHOULD KEEP THE LATE NIGHT/EARLY MORNING
RADIATIONAL FOG ACROSS THE AREA TO A MINIMUM.

&&

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

$$

SHORT TERM...MW
LONG TERM....MW
AVIATION.....RRS


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