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000
FXUS63 KARX 162043
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
343 PM CDT THU MAY 16 2013

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 343 PM CDT THU MAY 16 2013

WEAK HIGH PRESSURE WAS PROVIDING DRY AND QUIET WEATHER ACROSS THE
FORECAST AREA LATE THIS AFTERNOON. MEANWHILE...A SHORTWAVE WAS
MOVING ACROSS WESTERN/CENTRAL NEBRASKA GENERATING SHOWERS AND
THUNDERSTORMS ACROSS THESE AREAS. A WARM FRONT WAS SITUATED FROM
NORTHEAST NEBRASKA STRETCHING SOUTHEAST INTO SOUTH CENTRAL IOWA
THROUGH CENTRAL ILLINOIS. THE WAVE WILL PUSH EAST TONIGHT WITH
SHOWERS AND THUNDERSTORMS SPREADING INTO SOUTHWEST MINNESOTA AND
NORTHWEST IOWA LATE THIS AFTERNOON INTO THIS EVENING. THE WAVE IS
EXPECTED TO SLIDE ACROSS NORTHERN IOWA/SOUTHERN MINNESOTA LATE
TONIGHT...EDGING INTO THE FORECAST AREA AFTER MIDNIGHT TONIGHT.
LOCATIONS WEST OF HIGHWAY 52 WILL SEE THIS ACTIVITY MOVE IN BETWEEN
MIDNIGHT AND 3AM...THEN IT WILL SPREAD EAST TO ALONG THE MISSISSIPPI
RIVER AROUND SUNRISE. 850 MB MOISTURE TRANSPORT FOCUSES MAINLY ALONG
AND NORTH OF THE INTERSTATE 90 CORRIDOR FRIDAY MORNING INTO EARLY
FRIDAY AFTERNOON. FORECAST MODELS ARE SUGGESTING A MORE NORTHERLY
TRACK WITH THE CLUSTER OF SHOWERS AND STORMS SO HAVE INCREASED
PRECIPITATION CHANCES ACROSS SOUTHEAST MINNESOTA THROUGH NORTH
CENTRAL WISCONSIN. THE WARM FRONT IS EXPECTED LIFT NORTH SLIGHTLY ON
FRIDAY AS A POTENT TROUGH DIGS INTO THE SOUTHWEST CONUS AND SURFACE
LOW PRESSURE DEEPENS OVER THE HIGH PLAINS. BY LATE FRIDAY AFTERNOON
THE FRONT IS EXPECTED TO STRETCH FROM FAR SOUTHWEST WISCONSIN
THROUGH SOUTHERN MINNESOTA. THE CLUSTER OF SHOWERS AND STORMS TO
WEAKEN AND PUSH NORTHEAST OF THE AREA DURING THE LATE AFTERNOON.
HOWEVER...MESOSCALE MODELS....SUCH AS THE ARW...NMM...AND SPC WRF
GENERATE SHOWERS AND STORMS ALONG THE FRONT AS IT LIFTS NORTH INTO
THE UPPER MISSISSIPPI RIVER VALLEY. 0-3 KM MUCAPE VALUES CLIMB TO
1500 J/KG. GUIDANCE SUGGESTS THAT DEWPOINTS CLIMB INTO HE LOWER
60S RIGHT ALONG AND BEHIND THE WARM FRONT. THIS SEEMS REASONABLE
LOOKING AT DEWPOINTS BEHIND THE FRONT THIS AFTERNOON WHERE
DEWPOINTS HAVE CLIMBED INTO THE LOWER TO MID 60S. 0-6 KM BULK
SHEAR VALUES APPROACH 30 KTS ACROSS NORTHEAST IOWA...SOUTHEAST
MINNESOTA AND PORTIONS OF SOUTHWEST WISCONSIN. IF STORMS DEVELOP
FRIDAY AFTERNOON NEAR THE WARM FRONT...CANNOT RULE OUT AN ISOLATED
SEVERE STORM. THE MAIN HAZARD WOULD BE LARGE HAIL. HIGH
TEMPERATURES ON FRIDAY WILL RANGE FROM THE UPPER 50S TO AROUND 60
ACROSS FAR NORTHERN WISCONSIN TO THE MID TO UPPER 70S OVER PORTIONS
OF NORTHEAST IOWA.


.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 PM CDT THU MAY 16 2013

THE WARM FRONT IS EXPECTED TO DRIFT NORTHWARD FRIDAY NIGHT THROUGH
EARLY SATURDAY MORNING AS A VIGOROUS TROUGH DIGS INTO HE CENTRAL
PLAINS. RIDGING DEVELOPS OVER THE UPPER MISSISSIPPI RIVER VALLEY
FRIDAY NIGHT INTO SATURDAY MORNING AS MOIST...WARM AIR FLOWS INTO
THE FORECAST AREA IN THE WAKE OF THE FRONT. ONCE THE WARM FRONT
LIFTS NORTH OF THE AREA AND RIDGING MOVES IN THERE IS VERY LITTLE
FORCING TO WORK WITH WITHIN THE WARM SECTOR AND WARMER AIR MOVES IN
AT 850 MB...WITH CAPPING HOLDING STRONG THROUGH MUCH OF THE DAY.
DECIDED TO INCREASE HIGH TEMPERATURES ACROSS MUCH OF THE FORECAST
AREA. WILL HAVE TO KEEP A CLOSE WATCH ON THE CAP AND ANY WEAK
FORCING THAT COULD TRIGGER A THUNDERSTORM. IF A SURFACE BASED STORM
WOULD DEVELOP IT WOULD HAVE THE POTENTIAL TO PRODUCE LARGE HAIL.
THIS LOOKS UNLIKELY AT THIS POINT WITH THE RIDGING OVERHEAD AND
THE CAP STRENGTHENING THROUGH THE LATE AFTERNOON HOURS.

A VIGOROUS WAVE LIFTS NORTH OUT OF THE CENTRAL PLAINS SUNDAY
AFTERNOON AND IS EXPECTED TO MOVE INTO THE UPPER MISSISSIPPI RIVER
VALLEY. THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THE LATE MORNING
INTO THE EARLY AFTERNOON HOURS. CAPE AND SHEAR PROFILES WOULD SUPPORT
SEVERE THUNDERSTORMS WITH THE POTENTIAL FOR SUPERCELLS. 0-3 KM MUCAPE
VALUES INCREASE TO AROUND 1700 J/KG OVER SOUTHEAST MINNESOTA AND
NORTHEAST IOWA BY 18Z ON SUNDAY. 0-6 KM BULK SHEAR OF 25 TO 30
KTS...SUNDAY AFTERNOON...INCREASES TO 35 TO 40 KTS LATE IN THE
AFTERNOON INTO THE EVENING HOURS AS SURFACE LOW PRESSURE DEEPENS
OVER NORTHWEST IOWA/SOUTHEAST SOUTH DAKOTA. 0-1 KM SHEAR ALSO
INCREASES TO AROUND 20 KTS LATE SUNDAY AFTERNOON INTO SUNDAY
EVENING. THE HIGHEST CHANCES FOR SEVERE THUNDERSTORMS APPEARS TO
BE ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA SUNDAY AFTERNOON
INTO SUNDAY EVENING. LARGE HAIL...DAMAGING WINDS...AND POSSIBLY AN
ISOLATED TORNADO CANNOT BE RULED OUT. ANOTHER ROUND OF STRONG TO
POSSIBLY SEVERE THUNDERSTORMS ARE POSSIBLE ON MONDAY INTO MONDAY
NIGHT AS THE TROUGH CLOSES INTO A LOW OVER SOUTH DAKOTA AND
EMBEDDED WAVES IN SOUTHWEST FLOW ALOFT CONTINUE TO IMPACT THE
REGION. THE LOW WILL EDGE EAST TUESDAY THROUGH THURSDAY BRINGING
PERIODIC CHANCES FOR SHOWERS AND POSSIBLY THUNDERSTORMS TO THE
REGION. HIGHS WILL FALL INTO THE 70S ON TUESDAY THEN INTO THE 60S
ON WEDNESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1237 PM CDT THU MAY 16 2013

HIGH PRESSURE WILL PROVIDE VFR CONDITIONS THIS AFTERNOON.

FOR TONIGHT...A THUNDERSTORM COMPLEX /CURRENTLY DEVELOPING ACROSS
SOUTH CENTRAL SOUTH DAKOTA AND NORTH CENTRAL NEBRASKA/ WILL MOVE
INTO KRST AROUND 17.08Z AND KLSE AROUND 17.11Z. AS THIS SYSTEM
APPROACHES THE AREA,,,CEILINGS WILL GRADUALLY LOWER FROM 20K LATE
THIS AFTERNOON TO 3-4K AFTER 17.08Z. THE SOUNDINGS ARE SUGGESTING
THAT THERE WILL BE POTENTIAL FOR MVFR CEILINGS. HOWEVER WITH THE
MODELS OVERDOING THE LOW LEVEL MOISTURE LATELY AND NO CEILINGS
THAT LOW CURRENTLY...HAVE HELD OFF ADDING IT TO THE TAFS AT THIS TIME.


&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...BOYNE