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000
FXUS63 KARX 110836
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
336 AM CDT TUE JUN 11 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM CDT TUE JUN 11 2013

WATER VAPOR IMAGERY/RAP 500MB ANALYSIS SHOWING A BROAD RIDGE OF HIGH
PRESSURE IN PLACE ACROSS THE CENTRAL CONUS WITH A VIGOROUS WAVE OF
LOW PRESSURE PUSHING EAST ACROSS NV TOWARD THE 4-CORNERS AREA. BROAD
ISENTROPIC LIFT/MOISTURE TRANSPORT AHEAD OF THIS LOW WAS PRODUCING A
COMPLEX OF THUNDERSTORMS FROM EASTERN MT...SOUTHEASTWARD INTO
SD/NEB. ALSO NOTED WAS A WEAK TROUGH OF LOW PRESSURE TOPPING THE
RIDGE. THIS WAS KICKING OFF SOME VERY ELEVATED SHOWERS/ISOLATED
THUNDER ACROSS PORTIONS OF NORTHERN MN. MEANWHILE...SURFACE MAP
EARLY THIS MORNING HAS A WEAK RIDGE OF HIGH PRESSURE FROM
WI...SOUTHWARD THROUGH THE LOWER MISSISSIPPI RIVER VALLEY. SKIES
WERE MOSTLY CLEAR ACROSS THE IMMEDIATE FORECAST AREA WITH
TEMPERATURES SITTING IN THE UPPER 50S TO THE MIDDLE 60S.
TEMPERATURES/DEW POINT SPREAD CURRENTLY RANGING FROM ZERO TO 5
DEGREES. WITH CALM/LIGHT WINDS UNDER THE RIDGE OF HIGH
PRESSURE...STILL EXPECTING AREAS OF FOG TO DEVELOP DURING THE
PRE-DAWN/SUNRISE HOURS...THOUGH NOT AS BAD AS WHAT OCCURRED MONDAY
MORNING.

OF IMMEDIATE CONCERN...WILL BE SHRA/TS THREAT ALONG AND NORTH OF
I-94 TODAY. THIS AREA WILL BE IN THE RIGHT ENTRANCE REGION OF 300MB
JET AND IN WEAK 700-500MB FRONTOGENETIC ZONE ASSOCIATED WITH THE
SHORTWAVE TROUGH PASSING TO THE NORTH. THIS CONVECTION LOOKS TO BE
VERY ELEVATED WITH THE UNSTABLE LAYER AT OR ABOVE 12-15KFT. QUESTION
WILL BE IF ANY RAIN CAN MAKE IT TO THE GROUND BEFORE EVAPORATING.
WILL INCLUDE SLIGHT CHANCE POPS TO ACCOUNT FOR THIS.
OTHERWISE...WILL BE SEEING INCREASE IN MID-HIGH CLOUD ACROSS THE
AREA TODAY IN BROAD ISENTROPIC ASCENT IN ADVANCE OF THE WAVE OF LOW
PRESSURE MOVING ACROSS THE COLORADO ROCKIES. DESPITE INCREASING CLOUD
COVER TODAY...TEMPERATURES WILL ACTUALLY BE A COUPLE DEGREES ABOVE
NORMAL FOR ONCE...TOPPING OFF IN THE UPPER 70 TO THE LOWER 80S.

FOR TONIGHT...INCREASING MOISTURE TRANSPORT/ISENTROPIC LIFT AHEAD OF
LOW PRESSURE MOVING OUT INTO THE PLAINS EXPECTED TO FUEL ELEVATED
ACCAS SHOWER/THUNDERSTORMS ACROSS OUR FORECAST AREA GOING INTO THIS
EVENING/OVERNIGHT. WRF MODELS THEN SHOW A MORE INVIGORATED
THUNDERSTORM COMPLEX KICKING OFF OVER SD AROUND MIDNIGHT. NAM
FORWARD PROPAGATING CORFIDI VECTORS WOULD MOVE THIS COMPLEX EASTWARD
INTO AREAS ALONG AND SOUTH OF I-94 TOWARD WEDNESDAY MORNING. IN
FACT...THE NSSL WRF SHOWS HINTS OF A BOW ECHO AS THE COMPLEX FOLLOWS
ALONG THE NOSE OF BETTER MOISTURE TRANSPORT/CAPE POOL. WOULD NOT BE
SURPRISED IF THIS CONVECTION TURNS SEVERE WITH 0-3KM BULK SHEAR IN
THE 35-45KT RANGE FOR A MAINLY DAMAGING WIND THREAT ALONG WITH SOME
LARGE HAIL. WILL HAVE TO KEEP A VERY CLOSE EYE ON THIS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 336 AM CDT TUE JUN 11 2013

AFOREMENTIONED THUNDERSTORM COMPLEX EXPECTED TO ROLL THROUGH THE
AREA DURING THE MORNING HOURS. THEN...WITH THE WAVE OF LOW PRESSURE
MOVING EAST ACROSS NORTHERN IL DURING THE AFTERNOON
HOURS...EXPECTING DEFORMATION AREA/MID-LEVEL FRONTOGENETIC AREA
SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE AREA...MAINLY ALONG
AND SOUTH OF I-94. COULD SEE SOME HEAVIER RAINFALL AT TIMES IN THIS
FORCING WITH RAINFALL AMOUNTS APPROACHING 1/2 INCH BEING FAIRLY
COMMON WITH ISOLATED HIGHER AMOUNTS THROUGH THE AFTERNOON HOURS.
SHOWERS/THUNDERSTORMS LOOK TO LINGER INTO THE EVENING...THEN PUSHING
OUT AFTER MIDNIGHT. AN ADDITIONAL 1/4 TO 1/2 INCH OF RAINFALL WILL
BE POSSIBLE. WITH THE WET SOILS...THIS RAINFALL COULD CAUSE SOME
RUNOFF ISSUES. A HYDROLOGY SECTION IS INCLUDED BELOW TO DISCUSS THE
IMPACTS OF THE HEAVIER RAINFALL.

LOOK FOR HIGH PRESSURE TO BUILD INTO THE AREA ON THURSDAY FOR MOSTLY
SUNNY AND SEASONABLY WARM TEMPERATURES IN THE 70S.

SHOWER AND THUNDERSTORMS RE-ENTER THE PICTURE FRIDAY NIGHT AS A
TROUGH OF LOW PRESSURE ROTATES NORTHEAST OUT OF THE PLAINS TOWARD
THE AREA. LOOK FOR LINGERING SHOWER AND THUNDERSTORM CHANCES THROUGH
THE REST OF THE PERIOD AS THE RIDGE GETS KNOCKED DOWN BY SEVERAL
TROUGHS ROTATING THROUGH. OTHERWISE...PLAN ON TEMPERATURES TO BE
RIGHT AROUND NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT
1133 PM CDT MON JUN 10 2013

MOSTLY CLEAR SKIES...RECENT RAIN AND RIDGE AXIS PASSING THROUGH THE
REGION WILL LIKELY LEAD TO AREAS OF FOG WITH SOME LIFR CONDITIONS
MAINLY ON THE WISCONSIN SIDE OVERNIGHT. WEST OF THE MISSISSIPPI
RIVER VISIBILITIES COULD DROP TO MVFR AT TIMES BUT EXPECT A BULK OF
THE AREA TO BE VFR WITH SLIGHTLY HIGHER DEW POINT DEPRESSIONS AND
SOUTHEAST FLOW ALREADY DEVELOPING AHEAD OF NEXT WAVE.

SPEAKING OF WHICH...SHORT WAVE COMING OUT OF WESTERN U.S. ALREADY
PRODUCING WARM AIR ADVECTION AND BIT OF MOISTURE RETURN OVER WESTERN
HIGH PLAINS AND WHILE THIS CONVECTION WILL LIKELY NOT REACH US...
ABUNDANT MID LEVEL DEBRIS CLOUDS WILL DURING TUESDAY MORNING HOURS.
THIS BROAD FRONTOGENETIC REGION AHEAD OF APPROACHING WAVE COULD
GENERATE SOME LIGHT SHOWERS INTO TUESDAY AFTERNOON BUT CONFIDENCE IS
NOT HIGH ENOUGH TO INCLUDE IN TAFS AT THIS TIME. GENERAL VFR
CONDITIONS EXPECTED TO LAST WELL INTO TUESDAY EVENING.

WILL BE WATCHING FOR DEVELOPMENT OF CONVECTION TUESDAY EVENING TO
THE WEST AND HOW MUCH WILL ADVECT INTO TAF SITES GOING INTO
WEDNESDAY MORNING.

&&

.HYDROLOGY...(MAINLY FOR WEDNESDAY INTO WEDNESDAY EVENING)
ISSUED AT 336 AM CDT TUE JUN 11 2013

FOR AREAS MAINLY ALONG AND SOUTH OF I-94...PLAN ON RAINFALL AMOUNTS
FROM TONIGHT THROUGH WEDNESDAY EVENING TO RANGE FROM 3/4 TO 1.5
INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WITH WET SOILS IN
PLACE...EXPECT SOME RUNOFF ISSUES AND SOME SIGNIFICANT WITHIN-BANK
RIVER RISES TO OCCUR. WILL HAVE TO KEEP A CLOSE EYE ON ANY AREAS
THAT MAY SEE LONGER DURATION/HIGHER RAINFALL RATES FOR FLOODING
POTENTIAL. STAY TUNED.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...

WI...NONE.
MN...NONE.
IA...NONE.

&&

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....SHEA
HYDROLOGY....DAS