Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 191132
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
632 AM CDT SUN APR 19 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CDT SUN APR 19 2015

MAIN FORECAST CONCERNS ARE ON SHOWER AND THUNDERSTORM CHANCES TODAY.
FOCUS THEN TURNS TO PRECIPITATION CHANCES AND COOLER TEMPERATURES INTO
THE WORK WEEK.

LATEST WATER VAPOR IMAGERY SHOWED AN UPPER LOW OVER THE CENTRAL
PLAINS WHILE A NORTHERN STREAM TROUGH WAS PUSHING EAST ACROSS THE
DAKOTAS/WESTERN MINNESOTA. THESE TWO FEATURES ARE CREATING A
COMPLEX PATTERN ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WITH NO
REAL STRONG FOCUS FOR PRECIPITATION  UNTIL THIS AFTERNOON ALONG A
COLD FRONT MARCHING EAST ACROSS THE FORECAST AREA. THEREFORE...BROAD
WARM AIR ADVECTION  ACROSS THE FORECAST  AREA EARLY TODAY WILL
RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS MAINLY ACROSS FAR
WESTERN WISCONSIN INTO NORTHEAST IOWA AND SOUTHEAST MINNESOTA.
HAVE REDUCED PRECIPITATION CHANCES FROM LATE THIS MORNING INTO
EARLY AFTERNOON WHEN WE SHOULD SEE A FEW BREAKS IN THE ACTIVITY.
THEN SURFACE BASED CAPE LOOKS TO BUILD AHEAD OF THE COLD FRONT TO
AROUND 300 J/K KG RESULTING IN SHOWERS AND THUNDERSTORMS
DEVELOPING ALONG THE FRONT MAINLY ACROSS NORTHEAST
IOWA...SOUTHEAST MINNESOTA...AND SOUTHWEST WISCONSIN. SHEAR IS
RATHER WEAK ACROSS THE REGION TODAY SO SEVERE THUNDERSTORMS ARE
NOT EXPECTED. THE NORTHERN STREAM TROUGH CONTINUES TO EDGE
EASTWARD LATE THIS AFTERNOON AS LOW PRESSURE LIFTS NORTHWARD FROM
THE MIDDLE MISSISSIPPI RIVER VALLEY. THE TROUGH WILL CONTINUE TO
DEEPEN AND THE RIGHT ENTRANCE OF A 250 MB JET STREAK WILL MOVE
OVER THE FORECAST AREA. WITH THE UPPER LEVEL SUPPORT WE SHOULD SEE
A SWATH OF RAIN SHOWERS MARCH EAST ACROSS THE AREA THIS EVENING
INTO THE OVERNIGHT HOURS. THIS IS WHEN MUCH OF WESTERN INTO
CENTRAL  WISCONSIN WILL SEE THE BULK OF THE RAINFALL OUT OF THIS
SYSTEM.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 332 AM CDT SUN APR 19 2015

A MAJOR PATTERN SHIFT IS IN STORE FOR THE ENTIRE GREAT LAKES
REGION GOING INTO THE WORK WEEK AS LOW PRESSURE SETS UP ACROSS
SOUTHER ONTARIO/LAKE SUPERIOR BRINGING COOL NORTHWEST FLOW TO THE
FORECAST AREA. 850 MB TEMPERATURES GO FROM +10 C ON SUNDAY THEN
FALL TO 0 TO -3 C BY MONDAY AFTERNOON. SHORTWAVES WILL ROTATE
AROUND THE TROUGH BRINGING CHANCES FOR RAIN SHOWERS TO THE AREA
MONDAY THROUGH TUESDAY. SOME SNOW MAY MIX IN AT TIMES MONDAY NIGHT
AND AGAIN TUESDAY NIGHT BUT SIGNIFICANT ACCUMULATIONS ARE NOT
EXPECTED. COOL NORTHWEST FLOW CONTINUES ACROSS THE REGION THROUGH
THE REMAINDER OF THE WORK WEEK AS SURFACE HIGH PRESSURE BUILDS IN.
QUIET AND COOL CONDITIONS ARE EXPECTED THROUGH THIS PERIOD WITH
HIGHS IN THE 40S TO LOWER 50S. RIDGING BUILDS ACROSS THE CENTRAL
CONUS THIS WEEKEND AND ATTEMPTS TO EDGE EASTWARD INTO THE WESTERN
GREAT LAKES. THIS WILL ALLOW HIGH TEMPERATURES TO GRADUALLY WARM
INTO THE LOWER TO MID 50S BY SATURDAY UNDER PARTLY TO MOSTLY
SUNNY SKIES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 632 AM CDT SUN APR 19 2015

TAFS SITES/FCST AREA GENERALLY BETWEEN WAVES OF PRECIPITATION THIS
MORNING INTO EARLY THIS AFTERNOON. ONLY ISOLATED TO SCT -SHRA WITH
VFR CONDITIONS EXPECTED THIS MORNING INTO EARLY THIS AFTERNOON. COLD
FRONT WILL APPROACH WITH STRONGER FORCING AND LIFT THIS AFTERNOON. A
BAND OF SHRA AND A FEW TSRA EXPECTED TO DEVELOP ALONG IT AND MOVE
SLOWLY ACROSS THE TAF SITES...MAINLY IN THE 19Z-02Z TIME-FRAME AT
KRST AND 22-08Z PERIOD AT KLSE. TSRA/CB APPEAR LIMITED TO THE FIRST
2 TO 3 HRS OF THE PRECIP PERIOD AT EACH TAF SITE...WHEN THE FRONT
WILL BE NEARBY AND INSTABILITY WILL BE THE STRONGEST. SOME LOWER
MVFR CIGS/VSBYS IN -SHRA AND BEHIND THE FRONT DURING THE MID/LATER
PORTIONS OF THE PRECIP PERIOD AT EACH TAF SITE. CIGS/VSBYS RETURN TO
VFR BY LATER EVENING AT KRST AND LATER OVERNIGHT AT KLSE AS FRONT
MOVES WELL EAST OF THE TAF SITES AND SUBSIDENCE/DRYING WITH HIGH
PRESSURE SPREADS IN. TIGHTER PRESSURE GRADIENT WITH THE HIGH FOR
BRISK/GUSTY NORTHWEST WINDS LATER THIS EVENING AND OVERNIGHT AS
WELL.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....RRS



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