000
FXUS63 KARX 142020
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
320 PM CDT FRI JUN 14 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 320 PM CDT FRI JUN 14 2013

LATEST WATER VAPOR IMAGERY SHOWED A RIDGE OVER THE THE UPPER
MIDWEST WITH EMBEDDED SHORTWAVES MOVING THROUGH IT. A TROUGH WAS
MOVING INTO EASTERN MONTANA/WYOMING GRADUALLY PUSHING
EAST/NORTHEAST. A SHORTWAVE WAS MOVING ACROSS WESTERN AND CENTRAL
IOWA...FUELING SHOWERS AND THUNDERSTORMS. SURFACE OBSERVATIONS
INDICATED LOW PRESSURE OVER NORTH CENTRAL NEBRASKA SHIFTING EAST.
A WARM FRONT WAS POSITIONED FROM EAST CENTRAL NEBRASKA...EAST
THROUGH SOUTHERN IOWA. A SECOND SURFACE LOW WAS TAKING SHAPE OVER
SOUTHERN SASKATCHEWAN...WITH A SURFACE TROUGH EXTENDING SOUTHWARD
THROUGH CENTRAL NORTH DAKOTA/SOUTH DAKOTA. HIGH PRESSURE WAS
CENTERED OVER LAKE SUPERIOR...MOVING EAST WITH SOUTH/SOUTHEAST WINDS
INCREASING ACROSS THE FORECAST AREA AND USHERING IN A SLIGHTLY
WARMER AND MOIST AIRMASS.

THE SURFACE TROUGH WILL CONTINUE TO ADVANCE EAST THIS EVENING AS THE
WARM FRONT FRONT LIFT INTO NORTHERN IOWA. A SHORTWAVE MOVING THROUGH
THE RIDGE WILL ENTER THE UPPER MISSISSIPPI RIVER VALLEY THIS
EVENING. MEANWHILE...850 MB MOISTURE TRANSPORT RAMPS UP ALONG AND
WEST OF THE INTERSTATE 35 CORRIDOR EARLY THIS EVENING THEN QUICKLY
FOCUSES EAST INTO THE FORECAST AREA. PERIODS OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED OVER THE AREA THIS EVENING INTO THE
OVERNIGHT HOURS. THE FOCUS FOR THE HEAVIEST RAINFALL WILL BE OVER
NORTHERN IOWA INTO FAR SOUTHWEST WISCONSIN...WHERE THE STRONGEST 850
MB MOISTURE TRANSPORT FOCUSES INTO THE FRONT. PRECIPITABLE WATER
VALUES CLIMB INTO THE 1.5 TO 1.9 RANGE ACROSS MUCH OF THE FORECAST
AREA THIS EVENING AND HOVER THERE THROUGH MUCH OF THE OVERNIGHT.
ALSO...WARM CLOUD DEPTH INCREASES TO AROUND 4KM ACROSS MUCH OF THE
REGION. THE THUNDERSTORMS SHOULD BE EFFICIENT RAIN PRODUCERS...WITH
LOCALLY HEAVY RAINFALL POSSIBLE. THE SURFACE TROUGH SLIDES THROUGH
LATE TONIGHT FOR LOCATIONS NORTH OF INTERSTATE 90...BUT THE WARM
FRONT LINGERS OVER NORTHERN IOWA INTO FAR SOUTHWEST WISCONSIN AND
THE MOISTURE TRANSPORT CONTINUES TO FOCUS INTO IT. THIS SHOULD LEAD
TO REPEATED ROUNDS OF SHOWERS AND STORMS OVER THESE AREAS...LEADING
TO POTENTIAL FLASH FLOODING. AREAS THAT HAVE RECEIVED RECENT HEAVY
RAINFALL ARE AT GREATEST RISK OF SEEING FLASH FLOODING. CANNOT RULE
OUT AN ISOLATED SEVERE HAIL REPORT OR TWO GIVEN ELEVATED CAPE VALUES
APPROACHING 2000 J/KG VERY LATE TONIGHT INTO SATURDAY MORNING.
HOWEVER...SHEAR IS LIMITED AND WITH VERY HIGH FREEZING LEVELS IT
WILL TAKE UPDRAFT ROTATION TO GROW LARGE ENOUGH HAILSTONES TO
OVERCOME THE HIGHER FREEZING LEVELS. SHOWERS AND STORMS WILL BE
ONGOING EARLY SATURDAY MORNING...ESPECIALLY ALONG AND SOUTH OF
INTERSTATE 90. WEAK RIDGING MOVES IN IN WAKE OF THE FIRST ROUND OF
SHOWERS/STORMS MID MORNING ON SATURDAY THEN ANOTHER SHORTWAVE
MOVES IN LATE SATURDAY MORNING INTO EARLY SATURDAY AFTERNOON.
ANOTHER ROUND OF SHOWERS AND STORMS EXPECTED WITH THIS WAVE. AGAIN
THE STORMS WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. THE
SURFACE TROUGH LOOKS TO BE POSITIONED ALONG THE INTERSTATE 35
CORRIDOR AROUND 15Z SATURDAY MORNING...THEN PUSHES EAST THROUGH
THE FORECAST AREA DURING THE LATE MORNING AND AFTERNOON HOURS.
DEPENDING ON WHETHER OR NOT WE SEE SOME SUNSHINE/DESTABILIZATION
IN THE WAKE OF THE FIRST ROUND OF ACTIVITY. THERE IS THE
POSSIBILITY OF SEEING A FEW STRONG TO SEVERE STORMS DEVELOPING
ALONG THIS SURFACE TROUGH. 0-6KM BULK SHEAR INCREASES IN THE
AFTERNOON HOURS TO AROUND 30 KTS AS THE SHORTWAVE MOVES IN.
ALSO...FORECAST SOUNDINGS SUGGEST WE COULD SEE SURFACE BASED CAPE
VALUES CLIMB TO AROUND 2000 J/KG. THE SHEAR LOOKS TO LAG BEHIND
THE WAVE SO THIS WOULD BE A LIMITING FACTOR FOR SEVERE POTENTIAL.
THE HIGHEST CHANCES FOR SHOWERS AND STORMS SATURDAY AFTERNOON WILL
OVER NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE STRONGEST
MOISTURE TRANSPORT FOCUSES INTO SOUTHERN AND EASTERN IOWA BY
SATURDAY AFTERNOON. ALSO...THE OVERNIGHT MCS ACTIVITY COULD HELP
PUSH THE WARM FRONT TO THE SOUTH. WILL HAVE TO KEEP A VERY CLOSE
EYE ON THE POSITION OF THE WARM FRONT ON SATURDAY. PLAN ON HIGH
TEMPERATURES ON SATURDAY IN THE MID TO UPPER 70S.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 320 PM CDT FRI JUN 14 2013

THE SURFACE TROUGH PUSHES EAST OF THE FORECAST AREA SATURDAY
EVENING. ANOTHER ROUND OF CONVECTION ALONG THE WARM FRONT LATE
SATURDAY AFTERNOON INTO SATURDAY EVENING OVER NORTHEAST IOWA AND FAR
SOUTHWEST WISCONSIN WILL HELP TO PUSH THE WARM FRONT BACK TO THE
SOUTH...CLOSER TO THE INTERSTATE 80 CORRIDOR. SHOWERS AND STORMS
SHOULD TAPER OFF AND DURING THE EVENING HOURS AND FOCUS
SOUTH/SOUTHEAST OF THE FORECAST AREA. WEAK HIGH PRESSURE THEN MOVES
INTO THE REGION WITH THE FORECAST AREA BETWEEN SYSTEMS SATURDAY LATE
NIGHT INTO SUNDAY. SUNDAY IS SHAPING UP TO BE A RATHER PLEASANT LATE
SPRING DAY. UNDER PARTLY SUNNY SKIES...PLAN ON HIGHS CLIMBING INTO
THE LOWER TO MID 80S. AN UPPER TROUGH THEN RACES SOUTHEAST SUNDAY
NIGHT OUT OF SOUTHERN MANITOBA/ONTARIO AND HEADS TOWARD THE FORECAST
AREA. THERE ARE SOME SLIGHT TIMING DIFFERENCES IN THE FORECAST MODELS
ON EXACTLY WHEN THE TROUGH WILL PASS THROUGH. CURRENT THINKING IS
THAT THE TROUGH SHOULD MOVE THROUGH LATE SUNDAY SUNDAY NIGHT INTO
MONDAY MORNING...BRINGING CHANCES FOR SHOWERS AND THUNDERSTORMS TO
THE AREA. THE TROUGH FINALLY EXITS THE REGION LATE MONDAY AFTERNOON
WITH HIGH PRESSURE BUILDING ACROSS THE REGION IN ITS WAKE. QUIET
NORTHWEST FLOW ALOFT AND SURFACE HIGH PRESSURE IN PLACE WILL PROVIDE
DRY AND QUIET WEATHER THROUGH AT LEAST WEDNESDAY. FORECAST MODELS
ARE SUGGESTING SOME WEAK IMPULSES WILL MOVE THROUGH THE AREA LATE IN
THE WEEK BRINGING SOME LOW CHANCES FOR SHOWERS AND STORMS TO THE
AREA. HOWEVER MODEL SOLUTIONS START TO DIVERGE BEYOND THURSDAY SO
HAVE LEANED TOWARD MODEL CONSENSUS BLEND. HIGH TEMPERATURES ARE
EXPECTED TO RANGE FROM THE 70S TO AROUND 80S


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 105 PM CDT FRI JUN 14 2013

SHORT WAVE ENERGY ALONG NORTHERN TIER OF STATES CONTINUES TO FIRE
THREAT FOR CONVECTION...EVEN WITH SHORT TERM RIDGE IN PLACE. TIMING
AND EXTENT OF THIS THREAT IS MAIN CHALLENGE FOR AVIATION WITH GOOD
VFR CONDITIONS IN PLACE RIGHT NOW.

EXPECT INITIAL DEVELOPMENT LATER TODAY TO THE WEST BUT UNCERTAINTY
IN WHERE AND EXACTLY WHEN. BANKING ON HIGHER CHANCES FOR STORMS TO
ROLL IN OVERNIGHT AND THEN PASS THROUGH TOWARDS DAYBREAK SATURDAY
WITH GENERAL RETURN TO VFR AFTER THAT. HARD TO GIVE EXACT TIMING OF
STORMS BUT WILL TRY AND NAIL DOWN 3-4 HOUR WINDOW WITH HIGHEST
CHANCES.

&&

.HYDROLOGY...THIS EVENING THROUGH SATURDAY EVENING
ISSUED AT 320 PM CDT FRI JUN 14 2013

HEAVY RAINFALL COULD LEAD TO FLASH FLOODING OVER PORTIONS OF
SOUTHEAST MINNESOTA INTO NORTHEAST IOWA THIS EVENING THROUGH
SATURDAY EVENING. THE AREAS OF GREATEST CONCERN ARE LOCATIONS THAT
RECEIVED HEAVY RAINFALL ON WEDNESDAY...SUCH AS PORTIONS OF DODGE
AND FILMORE COUNTIES IN SOUTHEAST MINNESOTA...AND MUCH OF
NORTHEAST IOWA ESPECIALLY FLOYD AND MITCHELL COUNTIES. 1 TO 2
INCHES OF RAINFALL ARE POSSIBLE BY SATURDAY EVENING. LOCALLY
HIGHER AMOUNTS ARE NOT OUT OF THE QUESTION UNDER ANY STRONGER
THUNDERSTORMS.

A LINE OF SHOWERS AND STORMS WILL TRACK ACROSS PORTIONS OF
NORTHEAST IOWA LATE THIS AFTERNOON INTO EARLY THIS EVENING.
SHOWERS AND THUNDERSTORMS WILL BECOME WIDESPREAD LATE THIS
EVENING INTO THE OVERNIGHT HOURS AS A WARM FRONT LIFTS INTO
NORTHERN IOWA AND MOISTURE TRANSPORT FOCUSES INTO THE FRONT.
ANOTHER ROUND OF SHOWERS AND STORMS ARE EXPECTED LATE SATURDAY
MORNING INTO SATURDAY AFTERNOON. THE THUNDERSTORMS TONIGHT THROUGH
SATURDAY WILL BE VERY EFFICIENT RAIN PRODUCERS WITH PRECIPITABLE
WATER VALUES OF 1.5 TO 1.9 INCHES AND WARM CLOUD DEPTHS HOVERING
AROUND 4000 METERS. WILL CONTINUE THE FLASH FLOOD WATCH THROUGH
SATURDAY EVENING.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR MNZ094-095.

IA...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR IAZ008>010-018-
     019-029-030.

&&

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION.....SHEA
HYDROLOGY...WETENKAMP