Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 020748
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
247 AM CDT SUN AUG 2 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 247 AM CDT SUN AUG 2 2015

OH THE FUN OF PREDICTING SUMMER TIME CONVECTION. LACK OF ACTIVITY
ALONG WARM FRONT SATURDAY EVENING HAS ALLOWED WARM FRONT TO LIFT
FARTHER NORTHEAST THAN EXPECTED. WITH MODEST LOW LEVEL JET FORMING
OVERNIGHT...HAVE ALREADY SEEN ELEVATED STORMS FORM NORTH OF
INTERSTATE 94 WITH LARGE HAIL. THIS ACTIVITY LIKELY TO CONTINUE INTO
DAY BREAK WITH MODEST MIXED LAYER CAPE AND ENOUGH CONVERGENCE FOR
REGENERATION OF STORMS.

THIS WARM FRONT PLACEMENT DOES HAVE IMPLICATIONS ON WEATHER LATER
TODAY AS STRONGER SHORT WAVE TROUGH DROPS OUT OF CANADIAN PRAIRIES
INTO WESTERN GREAT LAKES BY TONIGHT. TEMPERATURES AND DEW POINTS
WILL BE HIGHER THAN PREVIOUSLY EXPECTED LEADING TO HIGHER MIXED
LAYER CAPE VALUES /2500-3500 J/KG/ AS ASSOCIATED COLD FRONT
APPROACHES. COMBINE THIS WITH MODEST SHEAR AND STRONGER MID LEVEL
WINDS...ORGANIZED CONVECTIVE COMPLEXES POSSIBLE ACROSS MAINLY
WISCONSIN THIS AFTERNOON.

SOME QUESTION ON WHERE MAIN DEVELOPMENT WILL OCCUR BUT WEAK
PERFORMING MESOSCALE MODELS TEND TO HINT AT STORMS FORMING EAST OF
AREA AND COULD BACK BUILD TO THE WEST INTO HIGHER CAPE REGION. THIS
LEADS TO VERY CONDITIONAL THREAT FOR OUR WISCONSIN COUNTIES...BUT
WORTH WATCHING CLOSELY THROUGH THE DAY.

UPSTREAM WAVE SHOULD KEEP CONVECTION VERY PROGRESSIVE...MOVING
THREAT AREA QUICKLY SOUTHEAST OF THE AREA THIS EVENING SO RAIN
THREATS DROP OFF QUICKLY TO MATCH.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 247 AM CDT SUN AUG 2 2015

SHIFT OF UPPER LOW FROM HUDSON BAY INTO ONTARIO WILL PUSH BOUNDARY
SOUTH OF THE AREA AND MAKE FOR A FEW QUIET DAYS TO START THE WEEK IN
NORTHWEST FLOW. THIS WILL ALSO MAKE FOR COOLER TEMPERATURES...BELOW
NORMAL FOR A FEW DAYS. DROPPED FAVORED COLD BOGS A FEW CATEGORIES AT
NIGHT AS WELL.

MEDIUM RANGE MODELS REMAIN RELATIVELY INCONSISTENT FROM RUN TO RUN
FROM MID WEEK ON. HINTS THAT AMPLIFICATION IN FLOW TO THE WEST COULD
BREAK DOWN AS SERIES OF SHORT WAVES MOVE ACROSS THE NORTHERN TIER OF
STATES. WITH FORECAST CONFIDENCE LOW...SMALL RAIN THREATS REMAIN
LITTERED IN OUTER FORECAST PERIODS. STRONGEST POTENTIAL WAVE APPEARS
TO BE WEDNESDAY NIGHT INTO THURSDAY WHICH COULD GENERATE A COMPLEX
OF STORMS WITH INSTABILITY RESIDING JUST SOUTHWEST OF THE AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1153 PM CDT SAT AUG 1 2015

A WEAK WARM FRONT HAS MOVED NORTH THROUGH BOTH TAF SITES THIS
EVENING. THE LOW LEVEL JET WAS BEGINNING TO IMPINGE ON THIS FRONT
TO PRODUCE SOME MID LEVEL CLOUDS AND A LITTLE BIT OF CONVECTIVE
ACTIVITY NORTH OF THE FRONT. SINCE THE FRONT IS ALREADY PAST BOTH
TAF SITES...DO NOT SEE ANY OF THIS CONVECTION AFFECTING EITHER
SITE THROUGH THE NIGHT AND WILL JUST HAVE THE SCATTERED MID LEVEL
CLOUDS. THE LOW LEVELS WILL CONTINUE TO WARM THROUGH SUNDAY BEHIND
THE WARM FRONT AND AHEAD OF THE COLD FRONT TO PRODUCE A PRETTY
SIZABLE CAP. THIS SHOULD KEEP ANY AFTERNOON STORMS THAT FIRE
ALONG THE FRONT TO THE EAST OF BOTH TAF SITES CLOSER TO THE
SURFACE LOW AND SHORT WAVE TROUGH MOVING ACROSS NORTHERN WISCONSIN
WHERE THIS FORCING MAY BE ENOUGH TO BREAK THE CAP. THE SOUTHWEST
WINDS AHEAD OF THE FRONT WILL BE STRONG ENOUGH FOR SOME GUSTS TO
AROUND 25 KNOTS. ONCE THE COLD FRONT COMES THROUGH THE WIND WILL
SWITCH AROUND TO THE NORTHWEST AND COULD INCREASE FOR A COUPLE OF
HOURS AS THE CAP ERODES DEEPENING THE MIXED LAYER. THE WINDS
SHOULD SETTLE DOWN EARLY SUNDAY EVENING AS THE LOW LEVEL INVERSION
DEVELOPS.

&&

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

$$

SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...04


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