Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 220218
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
918 PM CDT MON JUL 21 2014

.UPDATE...OVERNIGHT
ISSUED AT 918 PM CDT MON JUL 21 2014

THE MCS CURRENTLY DEVELOPING ACROSS EASTERN NORTH DAKOTA INTO
NORTHWEST MINNESOTA IS THE FORECAST CONCERN FOR THE LOCAL AREA.
LATEST GUIDANCE SUGGESTS THAT THE 700-800 MB CAP WILL REMAIN
STRONG ENOUGH TO KEEP THE COMPLEX FROM DROPPING TOO MUCH
SOUTHEAST. CORFIDI VECTORS AND MCS MOTION WOULD SUGGEST A PATH
MORE ACROSS NORTHERN MINNESOTA INTO NORTHERN WISCONSIN...WITH A
SLIGHT POSSIBILITY OF CLIPPING THE FAR NORTHERN CWA. THUS...THE
THREAT FOR A DAMAGING WIND EVENT FOR THE AREA CONTINUES TO DROP.

THERE ARE SUGGESTIONS THAT THERE WILL BE AN INCREASE IN 850-700
MB MOISTURE TRANSPORT OVERNIGHT...AND THAT THE CAP WILL WEAKEN
ENOUGH TO ALLOW SHOWERS/STORMS TO DEVELOP TOWARD 10-12Z...MAINLY
ACROSS WESTERN INTO CENTRAL WISCONSIN. THIS WOULD BE IN
CONJUNCTION WITH THE PASSING MCS TO THE NORTH. THE LATEST RUNS OF
THE RAP/HRRR SUGGEST THIS IDEA COULD OCCUR AS WELL...SO HAVE
ADJUSTED PRECIPITATION CHANCES TO MAINLY AFTER 08Z FOR WESTERN
INTO CENTRAL WISCONSIN.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 331 PM CDT MON JUL 21 2014

MAIN FORECAST CONCERNS ARE SEVERE THUNDERSTORM POTENTIAL LATE
TONIGHT OVER NORTH CENTRAL WISCONSIN AND HEAT INDEX VALUES LATE
TUESDAY MORNING INTO TUESDAY AFTERNOON OVER PORTIONS OF NORTHEAST
IOWA INTO FAR SOUTHWEST WISCONSIN.

LATEST RADAR IMAGERY SHOWS THUNDERSTORMS DEVELOPING OVER PORTIONS OF
CENTRAL NORTH DAKOTA. THESE SHOULD BE THE BIRTH OF A THUNDERSTORM
COMPLEX THAT WILL RACE EAST TONIGHT ACROSS NORTHERN MINNESOTA INTO
PORTIONS OF NORTHERN WISCONSIN AND UPPER MICHIGAN. MOST OF THE
MESOSCALE MODEL GUIDANCE KEEPS THIS COMPLEX NORTH OF THE INTERSTATE
94 CORRIDOR. HOWEVER...THE NAM...WHICH IS A MAJOR OUTLIER AT THIS
TIME...SHOWS CONVECTION FIRING OVER WEST CENTRAL MINNESOTA LATE
THIS AFTERNOON INTO THIS EVENING THEN THIS CONVECTION RACES
SOUTHEAST INTO THE FORECAST AREA. LOOKING AT FORECAST SOUNDINGS
OVER MUCH OF THE FORECAST AREA THERE IS AN IMPRESSIVE ELEVATED
MIXED LAYER WHICH IS RESULTING IN A STRONG CAP IN PLACE. THE
CONVECTION WILL HAVE TO OVERCOME THIS CAP AND WITHOUT A STRONG LOW
LEVEL JET THIS WILL BE DIFFICULT TO DO. THE 17Z HRRR SHOWS A FEW
CELLS MAKING IN INTO WEST CENTRAL WISCONSIN AFTER MIDNIGHT SO WILL
HAVE TO SEE IF THIS PANS OUT. HAVE DECIDED TO REDUCE POPS ACROSS
MUCH OF THE FORECAST AREA TONIGHT WITH THE EXCEPTION OF CLARK AND
TAYLOR COUNTY WHERE THE MCS COULD IMPACT THESE AREAS WITH DAMAGING
WINDS THE MAY CONCERN.

A COLD FRONT THEN SAGS SOUTH ACROSS THE AREA ON TUESDAY. SOME OF
THE WARMEST AIR AT 925 MB MAKES IT INTO NORTHEAST IOWA INTO FAR
SOUTHWEST WISCONSIN WHERE 925 MB TEMPERATURES CLIMB TO AROUND 27
C. TEMPERATURES COULD CLIMB TO THE UPPER 80S TO AROUND 90 OVER
PORTIONS OF NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THESE
TEMPERATURES COMBINED WITH DEWPOINTS IN THE MID TO UPPER 70S WILL
PRODUCE HEAT INDEX VALUES AROUND 100. THIS HEAT LOOKS TO BE VERY
SHORT LIVED WITH THE COLD FRONT SWEEPING THROUGH LATE TOMORROW
AFTERNOON SO HAVE HAVE NOT ISSUED A HEAT ADVISORY AT THIS TIME.
SHOWERS AND STORMS WILL BE POSSIBLE ALONG THE FRONT TUESDAY
AFTERNOON INTO EARLY TUESDAY EVENING BUT AGAIN THE CAP WILL BE A
MAJOR LIMITING FACTOR. MOST OF THE FORECAST MODELS KEEP THE AREA
DRY. GIVEN THE AMOUNT OF SURFACE BASED CAPE THAT DEVELOPS AHEAD
OF THE FRONT OVER NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN...COULD SEE A STORM OR TWO DEVELOP ALONG THE FRONT LATE
IN THE AFTERNOON SO WILL KEEP CHANCES FOR SHOWERS AND
THUNDERSTORMS THROUGH THE LATE AFTERNOON INTO THE EARLY EVENING.
VERY COMFORTABLE TEMPERATURES RETURN IN THE WAKE OF THE FRONT
TUESDAY NIGHT WITH TEMPERATURES FALLING INTO THE UPPER 50S TO
LOWER 60S.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 331 PM CDT MON JUL 21 2014

HIGH PRESSURE BUILDS INTO THE REGION TUESDAY NIGHT AND REMAINS OVER
THE REGION THROUGH THURSDAY PROVIDING QUIET AND COMFORTABLE CONDITIONS.
PLAN ON HIGHS IN THE 70S WITH LOWS IN THE 50S TO AROUND 60. WITH
THE HIGH OVERHEAD WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR
SOME PATCHY VALLEY FOG DURING THE LATE NIGHT AND EARLY MORNING
HOURS THURSDAY MORNING...BUT CLOUD COVER COULD PREVENT THIS FROM
FORMING. CHANCES FOR SHOWERS AND THUNDERSTORMS RETURN THURSDAY
NIGHT INTO THE WEEKEND AS ACTIVE NORTHWEST FLOW SETS UP ACROSS THE
REGION. A TROUGH DIVES INTO THE UPPER MISSISSIPPI RIVER VALLEY ON
SUNDAY AND DEEPENS A LARGER SCALE TROUGH OVER THE ENTIRE GREAT
LAKES REGION EARLY NEXT WEEK. THIS WOULD SET THE STAGE FOR WELL
BELOW NORMAL TEMPERATURES OVER THE AREA GOING INTO EARLY NEXT
WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 627 PM CDT MON JUL 21 2014

FOCUS IS ON THUNDERSTORM POTENTIAL OVERNIGHT...WITH STORMS ALREADY
DEVELOPING ACROSS THE DAKOTAS. THIS COULD FORM A LONG-LIVED
COMPLEX...BUT CONFIDENCE IS GROWING THAT THIS FEATURE WILL MISS
KRST/KLSE WELL TO THE NORTH. HOWEVER...SOME INCREASING MOISTURE
TRANSPORT AND WARM ADVECTION COULD GENERATE ELEVATED STORMS
OVERNIGHT...POSSIBLY IMPACTING KRST/KLSE AFTER MIDNIGHT. HAVE
ADDED A VICINITY THUNDERSTORM GROUP FOR THIS POTENTIAL.
OTHERWISE...PLAN ON SOUTHERLY FLOW UNTIL A COLD FRONT PUSHES
THROUGH IN THE LATE MORNING THROUGH AFTERNOON HOURS. WIND SHIFT TO
THE NORTHWEST LOOKS TO TAKE PLACE BETWEEN 18-21Z...AND ANY STORMS
WILL LIKELY DEVELOP SOUTH/EAST OF THE TAF SITES TOMORROW
AFTERNOON.


&&

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

$$

UPDATE.......ZT
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....ZT


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