Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 191736
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1236 PM 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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1236 PM CDT SUN APR 19 2015

MAIN TAF CONCERNS ARE THUNDERSTORM CHANCES AT BOTH RST AND LSE TAF
SITES LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS...THEN IFR TO
MVFR CEILING CONDITIONS THIS AFTERNOON INTO MONDAY MORNING. THE
LATEST SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE CENTRAL PLAINS
STATES WITH A COLD FRONT EXTENDING NORTH INTO CENTRAL MINNESOTA.
LATEST 19.12Z NAM SUGGEST SOME ELEVATED INSTABILITY TO DEVELOP
ALONG AND JUST AHEAD OF THE COLD FRONT BY 20Z TODAY AND QUICKLY
WEAKENS THE INSTABILITY AROUND 00Z MONDAY. AS THE FRONT PUSHES
EAST THIS AFTERNOON...THE LIFT ASSOCIATED WITH THE FRONT WILL
ALLOW SHOWERS TO DEVELOP...WITH A FEW EMBEDDED THUNDERSTORMS. WILL
CONTINUE TO MENTION VCTS AT BOTH RST AND LSE TAF SITES BETWEEN 20Z
TODAY- 01Z MONDAY.

NEXT CONCERN ARE MVFR TO IFR CEILING CONDITIONS AT THE TAF SITES.
THE 19.12Z NAM/GFS SHOW LOW LEVEL SATURATION TO OCCUR ALONG THE COLD
FRONT THIS AFTERNOON. THE 19.12Z NAM BUFKIT SOUNDINGS INDICATE
MVFR CONDITIONS AT BOTH TAF SITES THROUGH MONDAY MORNING
HOURS...AND SUGGEST THE POSSIBILITY OF IFR CONDITIONS AT RST TAF
SITE THIS EVENING INTO THE EARLY MORNING HOURS. FOR NOW...WILL
CONTINUE MVFR CEILING CONDITIONS AT BOTH RST/LSE TAF SITES AROUND
12-15Z MONDAY AND LET LATER SHIFTS TO MONITOR IF IFR CONDITIONS
DEVELOP.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION...DTJ


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