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000
FXUS63 KARX 182321
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
621 PM CDT TUE JUN 18 2013

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 217 PM CDT TUE JUN 18 2013

WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A SHORTWAVE TROUGH
ROTATING THROUGH SOUTHERN WI...WITH OUR AREA IN GENERAL
SUBSIDENCE BEHIND THIS WAVE. OTHERWISE...A HIGHLY AMPLIFIED RIDGE WAS
BUILDING ACROSS THE INTERMOUNTAIN WEST AND HIGH PLAINS AREA WHILE A
DEEP TROUGH WAS DIGGING ALONG THE WEST COAST. RIDGE BUILDING AND
ASSOCIATED INCREASING HEAT/HUMIDITY COMBINED WITH OCCASIONAL ENERGIES
EJECTING OUT OF THE WESTERN TROUGH OVER THE RIDGE WILL SET THE STAGE
FOR AN INCREASINGLY ACTIVE CONVECTIVE SCHEME THROUGH THE WEEKEND.

FOR TONIGHT...SURFACE HIGH PRESSURE CENTERS ITSELF OVER LOWER
MICHIGAN WITH WEAK EAST-SOUTHEAST WINDS OVER THE FORECAST AREA.
MOSTLY CLEAR SKIES AND LIGHT WINDS EXPECTED TO YIELD FAIRLY COOL
TEMPERATURES...RANGING FROM THE MID 40S ALONG/NORTH OF I-94...TO THE
LOWER/MIDDLE 50S ELSEWHERE.

ON WEDNESDAY...SURFACE HIGH PRESSURE CONTINUES TO PUSH EAST INTO THE
EASTERN CONUS WHILE THAT LOW OVER THE WEST COAST MOVES INTO THE
INTERMOUNTAIN WEST. THIS SETS UP INCREASING 850MB MOISTURE TRANSPORT
INTO THE PLAINS WITH THE EASTERN PERIPHERY OF THIS TRANSPORT NOSING
INTO MN/IA. MEANWHILE...MODELS SHOWING A WEAK MID-LEVEL TROUGH
MOVING ACROSS THE DAKOTAS WHILE ANOTHER WAVE SLIPS SOUTHEAST THROUGH
WESTERN ONTARIO/NORTHERN MN. THIS IS EXPECTED TO SEND SOME
MID-CLOUD/ACCAS INTO AREAS WEST OF THE MISSISSIPPI RIVER...BUT LOOKS
TO REMAIN DRY WITH SHOWERS/THUNDERSTORMS HOLDING OFF TO OUR WEST.
OTHERWISE...WARM AIR ADVECTION PUSHES TEMPERATURES INTO THE
MID/UPPER 70S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 217 PM CDT TUE JUN 18 2013

FOR WEDNESDAY NIGHT INTO THURSDAY...SHOWER AND THUNDERSTORM CHANCES
INCREASE ACROSS THE FORECAST AREA AS A WARM FRONT PUSHES NORTH AND
850MB MOISTURE TRANSPORT AXIS TAKES AIM ON THE UPPER MISSISSIPPI
RIVER REGION. IN FACT...THE NAM IS DEPICTING 4500-4800J/KG OF 0-3KM
MUCAPE AND AROUND 1500J/KG MLCAPE ALONG WITH 0-3KM BULK SHEAR IN THE
25KT RANGE GOING INTO THURSDAY AFTERNOON. WILL HAVE TO WATCH THIS
CLOSELY FOR SEVERE POTENTIAL AS THE WARM FRONT MAKES ITS WAY ACROSS
THE AREA. ECMWF/GFS THEN SHOW A CONSISTENT SIGNAL SETTING UP FOR AN
EXTENDED WARM/HUMID AND ACTIVE CONVECTIVE PATTERN THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. LOOKS LIKE SOUTHWEST FLOW ALOFT SET TO
EJECT SYNOPTIC MID-LEVEL TROUGHS ALONG WITH MCV/S OUR WAY WHICH WILL
INTERACT WITH WARM/HUMID AIRMASS IN PLACE FOR A CHANCE OF SHOWERS
AND THUNDERSTORMS EVERY DAY. OTHERWISE...WITH HIGHS IN THE 80S AND
DEW POINTS INCREASING INTO THE 70S FOR FRIDAY AND INTO THE
WEEKEND...LOOK FOR AFTERNOON/EARLY EVENING HEAT IN DICES IN THE
MID/UPPER 90S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 621 PM CDT TUE JUN 18 2013

VFR CONDITIONS THROUGH THE PERIOD AS HIGH PRESSURE SLOWLY DRIFTS
EAST/SOUTHEAST. EVENING CUMULUS WILL GIVE WAY TO CLEAR SKIES
OVERNIGHT...AND WINDS WILL SHIFT TO THE SOUTH BY MID MORNING
WEDNESDAY. DAYTIME HEATING AND GRADUAL MOISTURE INCREASE WILL LEAD
TO A SCATTERED CUMULUS FIELD IN THE AFTERNOON WITH BASES BETWEEN 3
TO 4 KFT.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION...ZT