Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 070444
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1144 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 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1144 PM CDT MON JUL 6 2015

THE NORTHERN EDGE OF THE SMOKE IS APPROACHING BOTH TAFS SITES.
AS A RESULT...EXPECT THE MVFR VISIBILITY RESTRICTIONS TO IMPROVE
BETWEEN 07.06Z AND 07.10Z. AFTER THIS SMOKE MOVES OUT...
VISIBILITIES WILL BE VFR.

THE MVFR CEILING NORTHERN EDGE IS ALSO CLOSE TO THE TAF SITES AND
THIS CLEARING SHOULD MOVE INTO THEM BETWEEN 07.05Z AND 07.07Z.
ONCE THIS OCCURS...THE CEILINGS WILL BE MAINLY CLEAR. HOWEVER
THERE MAY STILL BE SOME SMOKE AROUND THE AREA ABOVE 15K FEET.

&&

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

$$

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



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