Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 062354
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
654 PM CDT MON JUL 6 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 245 PM CDT MON JUL 6 2015

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS A BROAD AREA OF WEAK
LOW PRESSURE OVER WESTERN WISCONSIN WITH A TRAILING COLD FRONT
FROM NORTHEAST IOWA INTO SOUTHWEST IOWA. LOCAL AND REGIONAL RADARS
SHOWING A DIMINISHING AREA OF DEFORMATION RAINS ON THE NORTHWEST
SIDE OF THE SURFACE LOW WITH JUST SCATTERED ACTIVITY AHEAD OF THE
FRONT. ALMOST ALL THE 06.12Z MESO SCALE MODELS HAD THE SCENARIO
WELL HANDLED AT 18Z AND INDICATE THAT BY 00Z...THE SURFACE LOW
SHOULD PROGRESS INTO NORTHEAST WISCONSIN WITH THE COLD FRONT INTO
SOUTHWEST WISCONSIN AND FAR EASTERN IOWA. THE DEFORMATION AREA OF
RAIN SHOULD CONTINUE TO DIMINISH AND BE CONFINED TO AREAS NORTH OF
THE SURFACE LOW. ANY CONVECTION THAT FIRES THIS AFTERNOON ALONG
THE FRONT WILL LIKELY BE ON THE FAR EASTERN FRINGES OF THE
FORECAST AREA BY 00Z OR FARTHER EAST. BASED ON THESE TRENDS...HAVE
LOWERED THE RAIN CHANCES FOR EARLY THIS EVENING TO THE 60 TO 70
PERCENT RANGE FOR THE FAR EAST AND DRY ACROSS THE NORTHWEST
SECTIONS AND THEN HAVE THE ENTIRE AREA DRY BY 03Z.

ONCE THE RAIN AND FRONT MOVE OFF TO THE EAST...HIGH PRESSURE IN
THE LOW LEVELS WILL START TO BUILD IN. THIS WILL ALLOW SKIES TO
CLEAR OUT WITH DRIER AIR COMING IN OVERNIGHT. LOOKING FOR
TEMPERATURES TONIGHT TO DIP INTO THE 50S BUT NOT EXPECTING THERE
TO BE ANY FOG ISSUES AS THE WINDS WILL STAY UP ENOUGH TO KEEP THE
BOUNDARY LAYER MIXED. BETTER FOG POTENTIAL FOR TUESDAY NIGHT WITH
TEMPERATURES DROPPING INTO THE UPPER 40S AND 50S WITH LIGHT WINDS.
SYSTEM APPROACHING FROM THE SOUTHWEST COULD THROW SOME UPPER
LEVEL CLOUDS OVER THE AREA...SO WITH THIS UNCERTAINTY...HAVE OPTED
NOT TO PUT FOG IN YET.

THE 06.12Z GFS AND 06.00Z ECMWF THEN SHOW THIS SYSTEM FROM THE
SOUTHWEST PASSING THROUGH THE MIDDLE MISSISSIPPI RIVER VALLEY WITH
THE RAIN STAYING SOUTH OF THE AREA. HOWEVER...THE 06.12Z NAM IS
FARTHER NORTH AND BRINGS SOME RAIN ACROSS NORTHERN IOWA INTO
SOUTHERN WISCONSIN. PLAN TO ONLY INCLUDE A VERY SMALL RAIN CHANCE
ACROSS THE EXTREME SOUTHERN SECTIONS OF THE FORECAST AREA
WEDNESDAY NIGHT TO ACCOUNT FOR THE NORTHERN SOLUTION.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 245 PM CDT MON JUL 6 2015

A ZONAL UPPER AIR PATTERN IS EXPECTED TO TURN TO THE SOUTHWEST AS
AN UPPER LEVEL LOW MOVES ONTO THE WEST COAST AND THEN OPENS AND
WEAKENS RAPIDLY AS IT MOVES TO THE NORTHERN ROCKIES BY THE END OF
THE WEEK. THIS PATTERN WILL ALLOW SEVERAL SHORT WAVE TROUGHS TO
COME OVER THE UPPER MIDWEST WITH COME CLUSTERING IN THE MODELS OF
ONE COMING THROUGH FRIDAY NIGHT. THE REMAINS OF THE UPPER LEVEL
LOW MAY THEN START TO RESTRENGTHEN IN THE LEE OF THE NORTHERN
ROCKIES AND THEN SLIDE ACROSS THE UPPER MIDWEST THROUGH THE
WEEKEND. THE FIRST WAVE SHOULD BE ACCOMPANIED BY A NORTHWARD
MOVING SURFACE BOUNDARY TO HELP FOCUS THE POTENTIAL CONVECTION AND
WILL HAVE UP TO SOME 50 PERCENT RAIN CHANCES ACROSS THE SOUTH
FRIDAY NIGHT. WILL ALSO CARRY ANOTHER ROUND OF UP TO 50 PERCENT
RAIN CHANCES SATURDAY NIGHT INTO SUNDAY AS THE UPPER LEVEL LOW
MOVES ACROSS THE REGION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 654 PM CDT MON JUL 6 2015

SMOKE IN THE WAKE OF THE COLD FRONT HAS ALREADY MOVED INTO KRST
WHERE VISIBILITIES HAVE DROPPED 1 3/4 MILES AND IT WILL BE MOVING
INTO KLSE WITHIN THE NEXT HOUR. ACCORDING THE AIR QUALITY FORECAST
GUIDANCE...THIS SMOKE IN THE FORM OF HAZE WILL KEEP VISIBILITIES
MVFR THROUGH 07.10Z AND THEN VISIBILITIES WILL IMPROVE.

WIND SPEEDS WILL DROP TO LESS THAN 10 MPH AND CEILINGS WILL BECOME
VFR BY 07.03Z AT KRST AND 07.04Z AT KLSE. ONCE THIS OCCURS...THEY
WILL REMAIN THAT WAY THROUGH THE REMAINDER OF TH TAF PERIOD.

&&

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

$$

SHORT TERM...04
LONG TERM...04
AVIATION...BOYNE



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