Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 092012
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
312 PM CDT WED JUL 9 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 312 PM CDT WED JUL 9 2014

CLOUDS WILL DECREASE ACROSS THE REGION LATE THIS AFTERNOON INTO
EARLY THIS EVENING WITH THE LOSS OF DAYTIME HEATING. HIGH PRESSURE
WILL SETTLE OVER THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT
PROVIDING DRY AND QUIET WEATHER. WILL HAVE TO KEEP AN EYE ON
PATCHY FOG POTENTIAL OVER CENTRAL WISCONSIN AND RIVER VALLEY
LOCATIONS. FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR SOME
CLOUDS TO SPREAD ACROSS THE REGION TONIGHT INTO EARLY THURSDAY
MORNING WITH BASES AROUND 5KFT. THIS ALONG WITH AN INCREASING
PRESSURE GRADIENT LATE TONIGHT SHOULD LIMIT FOG DEVELOPMENT. THE
HIGHEST CONFIDENCE ON FOG DEVELOPING WILL BE OVER THE WISCONSIN
RIVER VALLEY SO WILL MAINTAIN PATCHY FOG WORDING IN THESE AREAS
AND HAVE DECIDED TO REMOVE FOG ELSEWHERE. ANOTHER COOLER NIGHT IN
STORE FOR THE REGION WITH LOWS RANGING FROM THE MID 40S OVER NORTH
CENTRAL WISCONSIN TO THE MID TO UPPER 50S ACROSS NORTHEAST IOWA.

THE HIGH IS EXPECTED TO START SLIDING EAST OF THE REGION THURSDAY AS
LOW PRESSURE DEVELOPS OVER THE HIGH PLAINS. WINDS WILL INCREASE
OUT OF THE SOUTH AS THIS OCCURS BRINGING SLIGHTLY HIGHER DEWPOINT
AIR INTO THE REGION. IT WILL STILL BE A VERY NICE DAY ACROSS THE
REGION HOWEVER....WITH HIGHS CLIMBING INTO THE UPPER 70S TO AROUND
80 UNDER PARTLY TO MOSTLY SUNNY SKIES.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 312 PM CDT WED JUL 9 2014

A SHORTWAVE TROUGH APPROACHES THE REGION FROM THE DAKOTAS
THURSDAY NIGHT INTO FRIDAY MORNING WITH SHOWERS AND THUNDERSTORMS
SPREADING ACROSS THE FORECAST AREA FROM WEST TO EAST...MAINLY
AFTER MIDNIGHT THROUGH FRIDAY MORNING. FORECAST MODELS ARE IN GOOD
AGREEMENT BRINGING THE STRONGEST 850 MB MOISTURE TRANSPORT INTO
THE LOCAL AREA FRIDAY MORNING INTO EARLY FRIDAY AFTERNOON. HAVE
INCREASED PRECIPITATION CHANCES DURING THIS TIMEFRAME.

A FRONTAL BOUNDARY SLIPS SOUTH AND STALLS OVER THE FORECAST AREA
LATE FRIDAY NIGHT INTO SATURDAY. MODELS CONTINUE TO STRUGGLE A
LITTLE WITH THE EXACT PLACEMENT OF THIS BOUNDARY WHICH WILL HAVE A
VERY LARGE IMPACT ON THE FORECAST. THE ECWMF SHOWS 0-3 KM MUCAPE
VALUES INCREASING TO AROUND 1200-2000 J/KG SATUDAY AFTERNOON INTO
EARLY SUNDAY EVENING. 0-6 KM BULK SHEAR IS WEAK TO START THE
AFTERNOON BUT THEN INCREASES LATE IN THE AFTERNOON INTO SATURDAY
EVENING AS A TROUGH DIVES SOUTH OUT OF CANDADA. THERE REMAINS SOME
DETAILS TO WORK OUT SATURDAY AFTERNOON INTO SATURDAY NIGHT...BUT
CANNOT RULE OUT SOME STRONG TO SEVERE STORMS DURING THIS
TIMEFRAME. A SECONDARY TROUGH DROPS ACROSS THE REGION ON SUNDAY
AND IF THERE IS LINGERING INSTABILITY OVER THE AREA THERE SHOULD
BE STRONGER SHEAR TO WORK WITH. 0-6KM BULK SHEAR VALUES INCREASE
TO 40 TO 50 KTS BUT INSTABILITY WILL BE MORE OF A LIMITING
FACTOR. AT THIS TIME IT APPEARS THE BEST CAPE FOR SEVERE STORMS
WOULD BE OVER NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. BUT
AGAIN...THIS WILL ALL RIDE ON HOW MUCH INSTABILITY REMAINS OVER
THE REGION AFTER THE CONVECTION SATURDAY NIGHT INTO SUNDAY
MORNING.

AN UNSEASONABLY DEEP TROUGH THEN PLUNGES INTO THE UPPER MISSISSIPPI
RIVER VALLEY REGION SUNDAY NIGHT INTO TUESDAY WITH 850 MB
TEMPERATURES FALLING TO AROUND 4 C BY TUESDAY MORNING. 850
STANDARDIZED ANOMALIES FALL INTO THE -1.5 TO -2.0 RANGE...SUGGESTING
THE POTENTIAL TO SEE RECORD COOL HIGH TEMPERATURES. WITH THIS BEING
A CONSISTENT SIGNAL IN THE GUIDANCE DECIDED TO LOWER A HIGHS A FEW
DEGREES ON TUESDAY WITH HIGHS ONLY MAKING IT INTO THE 60S...WHICH
IS UNSEASONABLY COLD FOR THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1245 PM CDT WED JUL 9 2014

CUMULUS FIELD HAS DEVELOPED ACROSS MUCH THE REGION AND WILL
PERSIST THROUGH THE AFTERNOON HOURS AT 3-6KFT. ANY SHOWERS THAT
DEVELOP ARE EXPECTED TO STAY OFF TO THE EAST OF THE TAF SITES.
SKIES WILL CLEAR OUT TONIGHT AS A RIDGE OF HIGH PRESSURE MOVES IN
FROM THE WEST. SOME VALLEY FOG IS POSSIBLE AT LSE...BUT SOME MID
LEVEL CLOUDS MAY BE MOVING IN ALONG WITH SOME STRONGER LOW LEVEL
WINDS...SO CONFIDENCE WAS NOT HIGH ENOUGH TO PUT ANY REDUCTIONS
INTO THE FORECAST.

&&

.HYDROLOGY...
ISSUED AT 312 PM CDT WED JUL 9 2014

THE MISSISSIPPI RIVER LEVEL CONTINUES TO FALL. MCGREGOR AND
GUTTENBERG IOWA ARE THE ONLY ARX FORECAST POINTS THAT REMAIN IN
FLOOD. THESE POINTS ARE EXPECTED TO FALL BELOW FLOOD STAGE BY
THURSDAY. FOR THE CURRENT AND FORECAST RIVER LEVELS...SEE OUR
INTERNET PAGE AT WWW.WEATHER.GOV/LACROSSE.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...HALBACH
HYDROLOGY...WETENKAMP



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