000
FXUS63 KARX 140443
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1145 PM CDT THU JUN 13 2013

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 315 PM CDT THU JUN 13 2013

SURFACE OBSERVATIONS SHOWED HIGH PRESSURE OVER THE REGION PROVIDING
MOSTLY SUNNY SKIES. WATER VAPOR INDICATED A BROAD UPPER RIDGE
OVER THE CENTRAL CONUS. A TROUGH WAS LOCATED OVER THE PACIFIC
NORTHWEST...SLOWLY PUSHING NORTHEAST.

THE HIGH WILL PROVIDE QUIET WEATHER FOR THE ENTIRE FORECAST AREA
THIS EVENING THROUGH THE OVERNIGHT HOURS. PLAN ON MOSTLY CLEAR SKIES
WITH LOW TEMPERATURES RANGING FROM THE UPPER 40S OVER NORTH CENTRAL
WISCONSIN TO THE LOWER TO MIDDLE 50S ACROSS NORTHEAST IOWA.

CLOUDS WILL BE ON THE INCREASE DURING THE DAY ON FRIDAY AS THE RIDGE
BREAKS DOWN AND THE TROUGH LIFTS NORTH THROUGH MONTANA AND INTO
SOUTHERN SASKATCHEWAN. MEANWHILE...A WARM FRONT WILL EDGE EAST OUT
OF THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY. 850
MB MOISTURE TRANSPORT INCREASES ACROSS WESTERN IOWA/SOUTHERN
MINNESOTA LATE FRIDAY AFTERNOON. ONGOING SHOWERS AND THUNDERSTORMS
OVER EASTERN SOUTH DAKOTA SHOULD TRACK EAST WITH ADDITIONAL
DEVELOPMENT FURTHER EAST AS THE MOISTURE TRANSPORT RAMPS UP LATE
FRIDAY AFTERNOON INTO FRIDAY EVENING. HIGH TEMPERATURES ON FRIDAY
ARE EXPECTED TO RANGE FROM THE LOWER TO MID 70S OVER NORTH CENTRAL
WISCONSIN TO THE UPPER 70S ACROSS NORTHEAST IOWA.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 315 PM CDT THU JUN 13 2013

SHOWERS AND THUNDERSTORMS WILL SPREAD FROM WEST TO EAST ACROSS THE
FORECAST AREA FRIDAY EVENING. THE STRONGEST 850 MB MOISTURE
TRANSPORT IS FOCUSED INTO NORTH CENTRAL/NORTHEAST IOWA. THIS ALSO IS
THE AREA OF THE HIGHEST INSTABILITY WITH 0-3 KM MUCAPE VALUES OF
AROUND 2000 J/KG. ALSO. SURFACE LOW PRESSURE DEVELOPS OVER WESTERN
IOWA WITH A WARM FRONT EXTENDING EAST ACROSS NORTHERN IOWA.
DEPENDING ON EXACTLY WHERE THE WARM FRONT SETS UP...REPEATED ROUNDS
OF SHOWERS AND STORMS FRIDAY NIGHT THROUGH SATURDAY MORNING COULD
LEAD TO FLOODING CONCERN ACROSS NORTHEAST IOWA...PORTIONS OF
SOUTHEAST MINNESOTA...AND POSSIBLY INTO FAR SOUTHWEST WISCONSIN.
THIS RAIN ON TOP OF THE SATURATED SOILS WOULD GO DIRECTLY INTO
RUNOFF...SO WILL HAVE TO KEEP A VERY CLOSE EYE ON THIS. A FLASH
FLOOD WATCH MAY BE NEEDED ONCE CONFIDENCE INCREASES ON EXACTLY
WHERE THE WARM FRONT WILL SET UP.

THERE ARE SUGGESTIONS THAT THE WARM FRONT COULD SET UP CLOSER TO
THE INTERSTATE 80 CORRIDOR. THERE IS THE POTENTIAL FOR A FEW
STORMS CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WINDS...WITH
1-7 KM BULK SHEAR VALUES OF 30 TO 40 KTS EARLY FRIDAY NIGHT...THEN
THE SHEAR STARTS TO WANE LATE IN THE NIGHT. FORECAST SOUNDINGS
SHOW CAPE VALUES OF 1500 TO 2000 J/KG WHEN LIFTING FROM 875 MB.
THESE HIGHER CAPE VALUES OCCUR MAINLY LATE FRIDAY NIGHT INTO EARLY
SATURDAY MORNING. ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY IS
EXPECTED ON SATURDAY AS FLOW ALOFT TURNS ZONAL AND ANOTHER
SHORTWAVE MOVES ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA...THEN
PUSHES EAST INTO WESTERN WISCONSIN BY SATURDAY AFTERNOON. THERE
REALLY ISN/T APPRECIABLE FORCING WITH THE WAVE MOVING THROUGH ON
SATURDAY. HOWEVER...THERE APPEARS TO BE ENOUGH INSTABILITY TO
OVERCOME THE LACK OF STRONG FORCING...WITH 0-3 KM MUCAPE VALUES
CLIMBING TO AROUND 2500 J/KG. AN INTERESTING SHEAR PROFILE ACROSS
THE AREA ON SATURDAY...WITH RATHER WEAK FLOW FROM THE SURFACE
THROUGH 700MB. THE WINDS THEN INCREASE FROM ABOVE 700 THROUGH 200
MB...ESPECIALLY LATE SATURDAY AFTERNOON INTO SATURDAY EVENING.
CANNOT RULE OUT A FEW STRONG TO SEVERE STORMS AGAIN ON SATURDAY
WITH LARGE HAIL AND HEAVY RAINFALL THE MAINS CONCERNS.

ZONAL FLOW WILL BE IN PLACE ACROSS THE REGION FROM
SATURDAY NIGHT INTO SUNDAY AS THE TROUGH DIVES SOUTHEAST OUT OF
SOUTHERN MANITOBA AND PUSHES INTO THE FORECAST AREA LATE SUNDAY
AFTERNOON INTO SUNDAY NIGHT. AFTERNOON 0-3 KM MUCAPE VALUES SOAR
TO AROUND 3000 J/KG WITH 0-6 KM BULK SHEAR VALUES HOVERING IN THE
40 TO 45 KT RANGE. STRONG TO SEVERE STORMS APPEAR POSSIBLE SUNDAY
AFTERNOON INTO SUNDAY EVENING. HOWEVER...LATEST GUIDANCE SUGGEST
THE WAVE COULD MOVE IN LATER IN THE EVENING WHICH WOULD LIMIT THE
SEVERE THREAT. THE WAVE MOVES THROUGH THE REGION LATE SUNDAY NIGHT
THROUGH INTO MONDAY MORNING...THEN FINALLY PUSHES INTO THE EASTERN
GREAT LAKES MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE THEN BUILDS
INTO THE UPPER MISSISSIPPI RIVER VALLEY ON WEDNESDAY AND LOOKS TO
LINGER OVER THE REGION THROUGH THURSDAY...WITH HIGHS IN THE MID
70S TO AROUND 80 AND LOWS MAINLY IN THE 50S TO AROUND 60. GUIDANCE
SUGGEST A FEW WEAK DISTURBANCES COULD PUSH THROUGH THE RIDGE
BRINGING SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS WEDNESDAY
NIGHT INTO THURSDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY EVENING)
ISSUED AT 1145 PM CDT THU JUN 13 2013

HIGH PRESSURE BUILDS ACROSS THE REGION TONIGHT...WITH SKC SKIES AND
VRB TO LIGHT EAST WINDS. HIGH CLOUDS WILL BE ON THE INCREASE FRI
AFTERNOON...AHEAD OF AN ANTICIPATED AREA OF SHRA/TS MOVING NORTHEAST
AHEAD OF A WARM FRONT. PCPN IS LIKELY FOR KRST/KLSE FRIDAY NIGHT
INTO SATURDAY...WITH A LOWERING IN CIG HEIGHTS AS THE SHRA/TS MOVE
IN. PERIODS OF MVFR APPEARS LIKELY AT THIS TIME...WITH SOME
RESTRICTIONS IN VSBY. PARAMETERS SUGGEST THAT THE SHOWERS AND STORMS
COULD BE EFFICIENT RAIN PRODUCERS...AND HEAVY RAIN WILL BE POSSIBLE.
WINDS WILL INCREASE AND TURN FROM EAST TO SOUTHEAST ON FRIDAY.

SOME MESO MODELS ARE SUGGESTING THE POTENTIAL FOR SCT/ISOLD
SHRA/TS AHEAD OF THE EXPECTED PCPN FOR FRIDAY NIGHT...DEVELOPING IN
THE MID LEVEL WARM AIR ADVECTIVE WING OF THE APPROACHING SYSTEM. AT
THIS TIME...ANYTHING THAT WOULD DEVELOP WOULD COME OUT OF A MID /10
KFT/ LEVEL CLOUD DECK...WITH MINIMAL/IF ANY ACCUMULATIONS. ACTIVITY
IS NOT A FOR SURE THING...AND LOOKS LIMITED IN AREAL EXTENT...SO
WILL LEAVE OUT OF THE TAFS FOR NOW.

&&

.HYDROLOGY...FRIDAY NIGHT THROUGH SATURDAY
ISSUED AT 315 PM CDT THU JUN 13 2013

FRIDAY NIGHT THROUGH SATURDAY HOLDS THE POTENTIAL TO BRING
PERIODS OF HEAVY RAINFALL TO NORTHEAST IOWA...WHICH COULD QUICKLY
LEAD TO FLASH FLOODING SINCE THE SOILS ACROSS PORTIONS OF
NORTHEAST IOWA ARE ALREADY SATURATED FROM RECENT RAINS.
ALSO...PORTIONS OF SOUTHEAST MINNESOTA AND FAR SOUTHWEST WISCONSIN
COULD BE IMPACTED DEPENDING ON WHERE A FRONTAL BOUNDARY SETS UP
FRIDAY NIGHT. A FEW ROUNDS OF THUNDERSTORMS ARE EXPECTED FROM
FRIDAY NIGHT THROUGH SATURDAY. WITH WARM CLOUD DEPTHS OF 4.2KM AND
PRECIPITABLE WATER VALUES OF 1.5 TO 2 INCHES...THE STORMS WILL BE
EFFICIENT RAIN PRODUCERS. THE AREA THAT LOOKS MOST SUSCEPTIBLE WILL
BE ACROSS PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN.
THESE AREAS WERE HIT PRETTY HARD ON WEDNESDAY WITH RAINFALL
AMOUNTS RANGING FROM 1 TO 4 INCHES.

&&

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

$$

SHORT TERM....WETENKAMP
LONG TERM.....WETENKAMP
AVIATION......RIECK
HYDROLOGY.....WETENKAMP