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000
FXUS63 KARX 160456
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1156 PM CDT WED MAY 15 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 340 PM CDT WED MAY 15 2013

LATEST RADAR SHOWED A NARROW BAND OF SHOWERS DRIFTING SOUTH ACROSS
THE FORECAST AREA THIS AFTERNOON. THIS BAND WAS LOCATED ACROSS
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. RAINFALL AMOUNTS HAVE
BEEN LIGHT...RANGING FROM A TRACE TO 0.02. THIS BAND WAS BEING
SUPPORTED BY A WEAK SHORTWAVE MOVE OVER THE REGION. THE SHORTWAVE
WILL EXIT THE AREA EARLY THIS EVENING.

A SECONDARY SHORTWAVE WILL MOVE ACROSS NORTHERN WISCONSIN THIS
EVENING...BRINGING SOME PASSING CLOUDS TO THE AREA. THIS SHORTWAVE
WAS GENERATING SOME SHOWERS OVER FAR NORTHERN MINNESOTA. WILL HAVE TO
KEEP A CLOSE WATCH ON THE WAVE THIS EVENING TO SEE IF THE SHOWERS
HOLD TOGETHER AS IT PUSHES SOUTH. CURRENT THINKING IS THAT THEY WILL
DISSIPATE AFTER SUNSET. IF THEY HOLD TOGETHER...SOME SPRINKLES COULD
IMPACT LOCATIONS NORTH OF THE I-94 CORRIDOR. OTHERWISE...PLAN ON
SKIES RANGING FROM PARTLY CLOUDY TO MOSTLY CLEAR DURING THE
OVERNIGHT HOURS. OVERNIGHT LOWS ARE EXPECTED TO RANGE FROM THE MID
TO LOWER 40S OVER NORTH CENTRAL WISCONSIN TO THE MID 50S ACROSS
NORTHEAST IOWA.

A TROUGH DIGS INTO THE WEST COAST ON THURSDAY AS A LEADING SHORTWAVE
PUSHES EAST ACROSS THE DAKOTAS. MEANWHILE...DRY CANADIAN HIGH
PRESSURE BUILDS IN FROM THE NORTHEAST...INTO UPPER MICHIGAN
AND MUCH OF WISCONSIN. A FEW CUMULUS CLOUDS COULD DEVELOP ACROSS
PORTIONS OF CENTRAL INTO NORTH CENTRAL WISCONSIN ON THURSDAY.
OTHERWISE...SKIES WILL BE MOSTLY SUNNY. WITH FORECAST SOUNDINGS
SHOWING DEEP MIXING TO AROUND 5KFT SO EXPECT TO SEE DEWPOINTS MIX
OUT INTO THE UPPER 30S ACROSS CENTRAL AND NORTH CENTRAL WISCONSIN.
SURFACE LOW PRESSURE WILL DEEPEN ACROSS THE HIGH PLAINS LATE ON
THURSDAY AS A WARM FRONT LIFTS NORTH INTO SOUTHERN IOWA/NORTHERN
NEBRASKA. HIGH TEMPERATURES ON THURSDAY ARE EXPECTED TO RANGE FROM
THE MID 70S ACROSS NORTHERN WISCONSIN TO THE UPPER 70S OVER NORTHEAST
IOWA.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 PM CDT WED MAY 15 2013

FORECAST MODELS ARE IN REASONABLE AGREEMENT SHOWING AN MCS
DEVELOPING ACROSS NORTHERN NEBRASKA/SOUTHERN SOUTH DAKOTA THURSDAY
EVENING THEN PUSHING EAST DURING THE OVERNIGHT HOURS. THE MCS THEN
MOVES INTO SOUTHWEST MINNESOTA/NORTHWEST IOWA EARLY FRIDAY MORNING
THEN ADVANCES EAST INTO THE FORECAST AREA AND WEAKENS. 850MB
MOISTURE TRANSPORT FOCUSES INTO THE FORECAST AREA DURING THE DAY ON
FRIDAY AS THE WARM FRONT EDGES NORTH INTO NORTHERN IOWA AND CENTRAL
SOUTH DAKOTA. CURRENT THINKING IS THAT SHOWERS AND THUNDERSTORMS
WILL TRACK ACROSS THE FORECAST AREA FRIDAY MORNING AND WEAKEN AS
THEY PUSH EAST OF THE MISSISSIPPI RIVER AND RUN INTO MUCH DRIER
AIR. VERY LITTLE 0-3K MUCAPE TO WORK WITH AND 0-6 KM BULK SHEAR IS
AT 25 KTS OR LESS SO NOT ANTICIPATING SEVERE THUNDERSTORMS AT THIS
TIME. SOME LOCATIONS ACROSS SOUTHERN MINNESOTA AND NORTHEAST IOWA
COULD RECEIVE 3/4 TO POSSIBLY 1 INCH OF RAINFALL. THIS WILL ALL
DEPEND ON HOW FAR EAST THE MCS CAN MAKE IT BEFORE IS DIES OUT.
UPPER RIDGING THEN LOOKS TO DEVELOP ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY FRIDAY NIGHT WITH SOUTHERLY WINDS BRINGING A WARM AND
MOIST AIRMASS INTO THE REGION. MOST OF THE DAY ON SATURDAY MAY END
UP BEING DRY WITH THE RIDGE OVERHEAD. WILL MAINTAIN LOW CHANCES
FOR SHOWERS AND STORMS WITH SOME VERY WEAK IMPULSES MOVING THROUGH
THE RIDGE. A TROUGH DEEPENS OVER THE NORTHERN/CENTRAL PLAINS
SATURDAY NIGHT INTO SUNDAY MORNING AS A SECONDARY WAVE DIVES
SOUTHEAST OUT OF THE PACIFIC NORTHWEST. THE UPPER RIDGE SLIDES
EAST OF THE AREA BY SUNDAY AFTERNOON AS A VIGOROUS SHORTWAVE LIFTS
NORTH OUT OF THE CENTRAL PLAINS. THERE IS THE POTENTIAL FOR A FEW
ROUNDS OF SEVERE THUNDERSTORMS FROM SUNDAY AFTERNOON THROUGH
TUESDAY. FORECAST MODELS ARE SHOWING SOME DIFFERENCES ON THE
PLACEMENT OF THE SURFACE LOW DURING THIS TIMEFRAME SO DIFFICULT TO
PIN DOWN THE EXACT TIMING. THE FIRST ROUND COULD IMPACT THE REGION
SUNDAY AFTERNOON INTO SUNDAY EVENING WITH ANOTHER ROUND POSSIBLE
SUNDAY AFTERNOON. CAPE AND SHEAR PROFILES SUPPORT SEVERE
THUNDERSTORMS DURING THIS TIMEFRAME. THERE IS THE POTENTIAL FOR
SUPERCELL THUNDERSTORMS SUNDAY AFTERNOON MAINLY ALONG AND WEST OF
THE MISSISSIPPI RIVER...THEN POTENTIALLY ACROSS MUCH OF THE
FORECAST AREA ON MONDAY. IT IS IMPORTANT TO NOTE THAT ANY CHANGE
IN THE TRACK OF THE SURFACE LOW WILL HAVE AN IMPACT ON THE TIMING
AND SEVERE WEATHER TYPE. THE TROUGH FINALLY CLOSES INTO AN UPPER
LOW MONDAY NIGHT INTO TUESDAY WITH CHANCES FOR SHOWERS AND STORMS
PERSISTING. THE BEST FORCING AND INSTABILITY FOR SEVERE WEATHER
LOOKS TO PUSH SOUTHEAST OF THE AREA LATE MONDAY NIGHT. COOLER
TEMPERATURES RETURN ON TUESDAY WITH HIGHS ONLY IN THE 60S TO
AROUND 70. THE COOL TEMPERATURES PERSIST THROUGH WEDNESDAY AS THE
UPPER LOW REMAINS OVER THE REGION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1155 PM CDT WED MAY 15 2013

HIGH PRESSURE FROM MANITOBA AND ONTARIO CONTINUES TO EXTEND DOWN
INTO THE AREA LATE THIS EVENING. STILL SOME SCATTERED MID LEVEL
CLOUDS FLOATING AROUND UNDER THE RIDGE AXIS. EXPECT THIS TO BE THE
CASE THE REMAINDER OF THE NIGHT AS THE HIGH DRIFTS SLOWLY OFF TO
THE EAST. WINDS WILL BE LIGHT UNTIL THE RIDGE AXIS GETS OFF THE
EAST THURSDAY MORNING WHEN A LIGHT EAST TO SOUTHEAST FLOW WILL SET
UP. THE 16.00Z NAM BUFKIT SOUNDINGS CONTINUE TO SHOW THE POTENTIAL
FOR SOME AFTERNOON CUMULUS CLOUDS AND WILL MAINTAIN THESE IN THE
UPCOMING TAFS. A SHORT WAVE TROUGH COMING ACROSS THE NORTHERN
ROCKIES IS EXPECTED TO SPARK A MCS THURSDAY EVENING IN THE
MOISTURE RETURN ON THE BACK SIDE OF THE DEPARTING HIGH. SHOULD
START TO SEE A HIGH VFR CEILING MOVE IN THURSDAY EVENING AHEAD OF
THIS FEATURE. PLENTY OF MODEL DIFFERENCES ON THE TRACK OF THE MCS
ONCE IT FORMS WITH SOME MODELS TAKING IT NORTH OF THE AREA WHILE
OTHERS BRING IT INTO THE FORECAST AREA AND POSSIBLY IMPACT KRST
BEFORE 12Z FRIDAY.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04