Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 031137
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
637 AM CDT THU SEP 3 2015

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 334 AM CDT THU SEP 3 2015

SURFACE MAP EARLY THIS MORNING HAS A WARM FRONTAL BOUNDARY EXTENDING
FROM SOUTHERN MN EASTWARD INTO SOUTHERN WI. WEAK MOISTURE TRANSPORT
OVER THE FRONTAL BOUNDARY WAS FUELING A BAND OF STRONG THUNDERSTORMS
FROM CENTRAL WI INTO EAST CENTRAL WI. OTHERWISE THE IMMEDIATE
FORECAST AREA WAS FREE OF ANY SHOWER/THUNDERSTORMS WITH SCATTERED TO
BROKEN STRATOCUMULUS CLOUD COVER. IT WAS ALSO VERY MUGGY WITH
TEMPERATURE/DEW POINTS IN THE MIDDLE 60S TO MIDDLE 70S.

FOR TODAY...THE AFOREMENTIONED FRONTAL BOUNDARY WILL STAY PUT WHILE A
MID-LEVEL TROUGH AND PUSH OF MID-LEVEL PV-ADVECTION DRIFTS SOUTHEAST
ACROSS CENTRAL WI BY LATER THIS AFTERNOON. MOISTURE CONVERGENCE
ALONG THE FRONTAL BOUNDARY AND FORCING FROM MID-LEVEL TROUGH IS
EXPECTED TO FIRE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
EAST OF THE MISSISSIPPI RIVER. NAM DEPICTING AROUND 4000J/KG OF
MUCAPE OFF THE BUFKIT SOUNDING BY LATE THIS AFTERNOON BUT BULK SHEAR
IS RATHER WEAK...LESS THAN 25KT. SO...NO SEVERE WEATHER EXPECTED AT
THIS TIME BUT WITH VERY HUMID AIR MASS WITH PRECIPITABLE WATER
VALUES IN THE 1.5-2 INCH RANGE ANY PULSE TYPE STORM COULD PRODUCE
VERY HEAVY DOWNPOURS AND PERHAPS WIND GUST IN THE 30-40 MPH RANGE.
OTHERWISE...VERY WARM/MUGGY CONDITIONS WILL BE IN PLACE TODAY WITH
HIGHS WELL INTO THE 80S AND HEAT INDICES IN THE 90S SOUTHWEST OF I-
94.

LINGERING ISOLATED STORMS EXPECTED TO CONTINUE INTO THE OVERNIGHT
HOURS //MAINLY EAST OF THE MISSISSIPPI RIVER// AS THAT MID-LEVEL
TROUGH CONTINUES TO PUSH SOUTH ACROSS THE AREA. PLAN ON OVERNIGHT
LOWS IN THE MID 60S TO LOWER 70S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 334 AM CDT THU SEP 3 2015

FRIDAY LOOKS DRY FOR THE MOST PART. KEPT A SMALL-END CHANCE IN FOR
EAST OF THE MISSISSIPPI RIVER IN THE AFTERNOON AS THERE WILL STILL
BE SOME WEAK SURFACE CONVERGENCE AND TROUGHINESS ALOFT WITH FAIRLY
STEEP LAPSE RATES. LOOKING FOR HIGHS WELL INTO THE 80S WITH HEAT
INDICES IN THE 90S AGAIN SOUTHWEST OF I-94.

VERY WARM/MUGGY AIRMASS HANGS ON RIGHT INTO THE WEEKEND WITH SLOWLY
INCREASING SHOWER/THUNDER CHANCES SATURDAY NIGHT THROUGH SUNDAY
AHEAD OF AN APPROACHING COLD FRONT FROM THE NORTHERN PLAINS. PLAN ON
HIGHS SATURDAY AND SUNDAY WELL INTO THE 80S WITH AFTERNOON HEAT
INDICES TOPPING OFF IN THE 90S.

SHOWERS AND STORMS BECOMING LIKELY SUNDAY NIGHT AS THE COLD FRONT
PUSHES EAST INTO THE REGION. SEVERE THREAT WITH THIS COLD FRONTAL
PASSAGE LOOKS MINIMAL AT THIS POINT AS CAPE DIVES OFF AND BETTER
BULK SHEAR BEING POST FRONTAL. WILL HAVE TO KEEP AN EYE ON IT THOUGH.

COOLER WEATHER ON TAP FOR LABOR DAY INTO MID-WEEK AS MID-LEVEL
TROUGH DOMINATES THE REGION. COLD BE A FEW LINGERING SHOWERS AND
STORMS LABOR DAY MORNING...BUT LOOKING TO CLEAR BY MIDDAY AT THIS
TIME. SHOWERS AND STORM CHANCES RE-ENTER THE PICTURE TUESDAY LASTING
THROUGH WEDNESDAY AS A COUPLE EMBEDDED SHORTWAVE TROUGHS WITHIN THE
LONGWAVE TROUGH ROTATE THROUGH.

LOOK FOR HIGHS IN THE UPPER 70S/LOWER 80S ON MONDAY...COOLING
INTO THE MIDDLE 60S/LOWER 70S BY WEDNESDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 637 AM CDT THU SEP 3 2015

NOCTURNALLY DRIVEN MVFR CLOUD AND/OR VISIBILITY WILL DISSIPATE AT
BOTH SITES IN THE 03.14Z TO 03.15Z TIME FRAME WITH VFR CONDITIONS
THEREAFTER. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE
ACROSS CENTRAL/SOUTHERN WI THIS AFTERNOON/EVENING...BUT THINK
CONVECTIVE ACTIVITY WILL REMAIN EAST OF TAF AIRFIELDS AND WILL
KEEP FORECAST DRY. HOWEVER...LOWER VFR CLOUD DECK COULD SPILL
INTO THE MS RIVER VALLEY AND IMPACT KLSE THIS EVENING.

FORECAST GUIDANCE SHOWING LIGHT WIND LAYER TONIGHT DEEPENING TO
BETWEEN 10 AND 15 KFT AT KLSE...MORE THAN ENOUGH FOR DENSE FOG.
HOWEVER...UNCERTAINTY IN DEGREE OF CLOUD COVER PRECLUDES DROPPING
CONDITIONS TOO FAR AT THIS POINT. FOR NOW...WILL INTRODUCE MVFR
VISIBILITY IN MIST AT 04.09Z. AT KRST...SKIES SHOULD BE CLEAR
TONIGHT...BUT WINDS EXPECTED TO BE A BIT STRONGER ABOVE THE
NOCTURNAL INVERSION. WILL STILL INCLUDE MVFR VISIBILITY BY 04.08Z
GIVEN MOIST AIR MASS AND NOCTURNAL COOLING...BUT NOT EXPECTING
WIDESPREAD DENSE FOG AT THIS TIME.

&&

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

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...ROGERS


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