Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 240440
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1140 PM CDT SAT MAY 23 2015

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 205 PM CDT SAT MAY 23 2015

CURRENTLY WATCHING A WEAK MID-LEVEL TROUGH MOVING NORTHEASTWARD
ACROSS CENTRAL MN. NOSE OF WARM AIR ADVECTION AHEAD OF THIS WAVE WAS
PRODUCING ISOLATED LIGHT SHOWER ACTIVITY FROM CENTRAL MN AND ALONG
THE I-94 CORRIDOR IN WESTERN WI. OTHERWISE...SCATTERED TO BROKEN MID-
CLOUD WAS OVERHEAD ACROSS THE FORECAST AREA ASSOCIATED WITH THE
WAVE. DESPITE CLOUD COVER...TEMPERATURES RESPONDING NICELY TODAY
WITH READINGS THIS AFTERNOON MAINLY IN THE MIDDLE 70S.

FOR TONIGHT INTO SUNDAY...THE AFOREMENTIONED MID-LEVEL WAVE WILL
CONTINUE TO LIFT NORTHEAST WHILE LOSING ITS PUNCH. FOCUS THEN SHIFTS
TO A BIT MORE POTENT MID-LEVEL WAVE WITH INCREASED 850MB MOISTURE
TRANSPORT/WARM AIR ADVECTION PUSHING FROM THE SOUTHERN PLAINS INTO
IA BY SUNDAY MORNING. THIS WILL PRODUCE MORE MID-CLOUD COVER INTO
THE AREA ALONG WITH INCREASING SHOWER CHANCES WEST OF THE
MISSISSIPPI RIVER LATE TONIGHT...THEN INCREASING SHOWER COVERAGE
SPREADING ACROSS THE REST OF THE AREA SUNDAY. CAPE/INSTABILITY STILL
RATHER LIMITED PER LATEST BUFKIT...SO THUNDER MAY BE NIL OR VERY
ISOLATED IN NATURE. TEMPERATURES WILL TAKE SOMEWHAT OF A HIT SUNDAY
AS WELL WITH CLOUD/SHOWER COVERAGE. PLAN ON HIGHS IN THE 65-70
DEGREE RANGE.

SUNDAY NIGHT...SHOWERS/ISOLATED THUNDERSTORMS WILL CONTINUE ACROSS
THE AREA WITH DEEP/MOIST SOUTHERLY FLOW TAKING HOLD ACROSS THE
FORECAST AREA AS LOW PRESSURE RIDES NORTH THOUGH MN. WITH
PRECIPITABLE WATER VALUES PUSHING IN THE 1-5-1.8 INCH RANGE...LOOK
FOR FAIRLY WIDESPREAD 1/4-1/2 INCH RAINFALL THROUGH THE NIGHT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 205 PM CDT SAT MAY 23 2015

MEMORIAL DAY COULD BE SORT OF INTERESTING AS THE MAIN LOW
PROGRESSES NORTHWARD ACROSS MN. LATEST 12 NAM/GEM...AND TO A LESSER
EXTENT THE GFS/EC SUGGEST THE AREA CAPPING OFF IN THE WARM SECTOR.
THIS WOULD DIMINISH SHOWER/THUNDER CHANCES...SO DOESNT LOOK LIKE AN
ENTIRE WASHOUT. HELD HIGHEST SHOWER/THUNDER CHANCES FROM SOUTHEAST
MN INTO NORTH CENTRAL WI...CLOSER TO BETTER FORCING WITH INCOMING
COLD FRONT. OTHERWISE...LOOK FOR HIGHS WELL INTO THE 70S.

SOME UNCERTAINTY WITH SHOWER/THUNDERSTORM CHANCES...AND ANY SEVERE
THUNDERSTORM THREAT FOR MONDAY NIGHT AS THE FRONT PUSHES EVER SO
SLOWLY INTO THE AREA. 12Z NAM BUFKIT AND QPF OUTPUT SUGGEST CAP
HOLDS ACROSS THE AREA WELL INTO THE EVENING AHEAD OF THE FRONT...NOT
CONVECTING TIL AFTER MIDNIGHT. THIS SEEMS TO MAKE SENSE SINCE THERE
IS NOT A WHOLE LOT OF PUSH TO THE FRONT FOR FORCING AS MID-LEVEL
FLOW IS PARALLEL TO IT. AS SUCH...HELD HIGHER-END CHANCES CLOSER TO
THE FRONT FROM SOUTHEAST MN INTO NORTH CENTRAL WI. COULD BE A SEVERE
THREAT WITH THE CONVECTION WITH NAM SUGGESTING 0-3KM MUCAPE IN THE
1500-2000J/KG RANGE AND BULK SHEAR OF 35-45KT. WILL HAVE TO KEEP AN
EYE ON THIS.

FOR TUESDAY...THE MID-LEVEL TROUGH AND SURFACE COLD FRONT CONTINUE
TO EDGE SLOWLY ACROSS THE AREA. THIS MAY HAVE TO BE WATCHED AS WELL
FOR A LOW-END SEVERE THREAT IF CAPE CAN RECOVER IN ADVANCE OF THE
FRONT. THIS LOOKS LIKE IT COULD POSSIBLY BE AN NON-SUPERCELL TORNADO
TYPE OF ENVIRONMENT GIVEN SLOW ADVANCEMENT OF THE FRONT AND NAM
BUILDING CAPE IN THE 1500-2500J/KG RANGE. WILL JUST HAVE TO KEEP AN
EYE ON THIS AS THIS IS A FEW DAYS OUT AND THINGS/SETUP COULD CHANGE.

FOR WEDNESDAY THROUGH SATURDAY...

LOOKS LIKE A FAIRLY ACTIVE/HIGH ZONAL WEATHER PATTERN SHAPING UP
ACROSS THE CONUS WITH SEVERAL MID-LEVEL TROUGHS RIPPLING THROUGH FOR
PERIODIC SHOWER/THUNDER CHANCES. RIGHT NOW...PRETTY HARD TO PIN DOWN
TIMING ON ANY ONE OF THESE DISTURBANCES. OTHERWISE...COULD BE A
SLIGHT COOL DOWN FRIDAY INTO SATURDAY AS THERE IS SOME INDICATION OF
LONG WAVE TROUGH DIGGING DOWN FROM CANADA INTO THE UPPER MISSISSIPPI
RIVER/GREAT LAKES REGIONS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1140 PM CDT SAT MAY 23 2015

MAIN AVIATION CONCERN IS ONSET OF RAIN AND MVFR/IFR CEILINGS.
INITIAL RAIN THAT IS ADVANCING NORTH AHEAD OF THE MAIN SHORT WAVE
TROUGH IS HAVING A VERY TOUGH TIME ADVANCING INTO THE RELATIVELY
DRY AIR IN THE BOUNDARY LAYER OVER THE FORECAST AREA. THERE WERE
SOME SCATTERED LIGHT SHOWERS/SPRINKLES ALONG I-35 JUST WEST OF
KRST DURING THE LATE AFTERNOON AND EARLY EVENING...BUT THOSE DIED
OFF DIURNALLY. SHOWERS OUT AHEAD OF THE MAIN CONVECTION ACROSS
CENTRAL IA UP TOWARD KFSD ARE SUFFERING A SIMILAR FATE...SHOWING A
DIMINISHING TREND SINCE 03Z. MESOSCALE MODELS SHOWING THE RAIN
LOOKS TO HOLD OFF UNTIL 15Z OR SO. MAIN BAND MAY ALSO SHUNT EAST
IF THE LATEST MODEL TRENDS HOLD...SO THAT KLSE SEES MORE THAN
KRST. DO FEEL THERE WILL BE A BREAK FOR A TIME AFTER THE INITIAL
RAIN MOVES IN. BUT LOOKING LIKE DEEPER MOISTURE ARRIVES TO PROVIDE
A PERIOD OF RAIN AND IFR CONDITIONS BY SUNSET SUNDAY.



&&

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

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...MW


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