Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 052002
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
302 PM CDT SUN JUL 5 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 302 PM CDT SUN JUL 5 2015

THE FOCUS OF THE FORECAST CONTINUES TO BE ON THE RAIN CHANCES LATE
TONIGHT THROUGH MONDAY NIGHT.

WATER VAPOR SATELLITE SHOWS AN UPPER LEVEL LOW OVER NORTH CENTRAL
MANITOBA ALONG THE WESTERN SHORES OF HUDSONS BAY. SEVERAL SHORT
WAVE TROUGHS ARE EMBEDDED IN THE LONG WAVE TROUGH THAT EXTENDS
BACK TO THE SOUTHWEST INTO THE FAR PACIFIC NORTHWEST. THE 05.12Z
MODELS HAVE REMAINED CONSISTENT IN SHOWING THE UPPER LEVEL LOW
CONTINUING TO THE EAST AND REMAINING WELL NORTH OF THE AREA WHILE
THE SHORT WAVE TROUGHS COME THROUGH AND MAINTAIN THEIR POSITIVE
TILT. THE TIMING OF THE MAIN SHORT WAVE TROUGH LOOKS LIKE IT MAY
BE JUST A TOUCH SLOWER STAYING TO THE WEST OF THE AREA TONIGHT AND
THEN SWEEPING ACROSS MONDAY. THE BEST PV ADVECTION IN THE 500-300
MB LAYER WILL REMAIN NORTH OF THE AREA WITH SOME WEAK PV ADVECTION
EXPECTED TO COME ACROSS MAINLY THE NORTHERN SECTIONS OF THE
FORECAST AREA. THIS IS SIMILAR TO PREVIOUS MODEL RUNS...BUT THE PV
ADVECTION DOES LOOK TO BE MAYBE A LITTLE BIT STRONGER. THE 05.12Z
NAM ALSO SHOWS A LITTLE BETTER POTENTIAL FOR SOME JET DYNAMICS TO
COME INTO PLAY MONDAY AS IT BRINGS THE RIGHT ENTRANCE OF THE UPPER
LEVEL JET DOWN INTO NORTHERN MINNESOTA.

IN THE LOW LEVELS...THE COLD FRONT SHOULD EXTEND FROM NORTHWEST
WISCONSIN TO SOUTHWEST MINNESOTA BY LATE TONIGHT. THE FRONT
DEFINITELY LOOKS TO BE SLOWER ON THIS SET OF MODEL RUNS WITH IT
PROGRESSING INTO CENTRAL WISCONSIN AND EASTERN IOWA BY 00Z
TUESDAY BEFORE MOVING OFF TO THE EAST MONDAY EVENING. THIS SLOW
DOWN IN THE FRONT OPENS A WINDOW OF OPPORTUNITY FOR SOME SEVERE
STORMS ACROSS THE AREA. THE 05.12Z CR-NAM NEST SUGGESTS ANOTHER
WEAK SURFACE LOW WILL FORM OVER IOWA AND MOVE NORTH ALONG THE
FRONT INTO THE AREA MONDAY AFTERNOON. WITH THIS SCENARIO...THE
CAPE COULD POOL AHEAD OF THE LOW OVER THE SOUTHERN SECTIONS OF THE
AREA OR UP THROUGH ABOUT INTERSTATE 90. THE NAM BUILDS THE CAPE UP
TO 3000 J/KG OR HIGHER...WHICH IS TOO HIGH...BUT THE 05.12Z GFS
ALSO SHOWS A POOL OF 1500 J/KG OF ML CAPE IN THE SAME GENERAL
AREA. WITH THE POSITIVE TILT TO THIS SYSTEM...THE BEST DEEP LAYER
SHEAR WILL REMAIN BEHIND THE FRONT...BUT THE 0-3KM SHEAR COULD
INCREASE TO ABOUT 25 KNOTS RIGHT IN THE IMMEDIATE VICINITY OF THE
FRONT. THIS COULD PRESENT THE POSSIBILITY THAT SOME OF THE STORMS
COULD PRODUCE SOME SEVERE WINDS IF THEY CAN BECOME ORIENTED FROM
NORTHWEST AND SOUTHEAST WHICH WOULD BE PERPENDICULAR TO THE 0-3KM
SHEAR VECTOR. ONE OF THOSE SCENARIOS WHERE A LOT OF THINGS HAVE TO
COME TOGETHER JUST RIGHT...BUT WILL START INCLUDING THE THREAT FOR
SOME SEVERE IN OUR PRODUCT SUITE.

THE THREAT FOR SEVERE WEATHER AND FOR THE STORMS IN GENERAL SHOULD
DECREASE PRETTY QUICKLY MONDAY EVENING AS THE FRONT MAKES STEADY
EASTWARD PROGRESS AND OUT OF THE AREA. HIGH PRESSURE WILL BUILD IN
BEHIND THE FRONT AND REMAIN OVER THE REGION THROUGH TUESDAY NIGHT.
THE MID LEVEL FLOW LOOKS LIKE IT WILL BECOME NORTHWEST AGAIN WHICH
SHOULD RETURN THE SMOKE FROM THE CANADIAN AND ALASKAN WILDFIRES
BACK INTO THE UPPER MIDWEST. THE VERTICAL SMOKE FORECASTS SUGGEST
THIS SHOULD START TO RETURN MONDAY NIGHT.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 302 PM CDT SUN JUL 5 2015

AN UPPER LEVEL LOW IS EXPECTED TO MOVE ONSHORE FROM THE CENTRAL
PACIFIC DURING THE MIDDLE OF THE WEEK. THIS WILL TURN THE UPPER
LEVEL FLOW PATTERN TO A ZONAL PATTERN INITIALLY AND THEN TO THE
SOUTHWEST. WITH THE PATTERN...BOTH THE GFS AND 05.12Z ECMWF DO NOT
SHOW ANY STRONG SYSTEMS AFFECTING THE UPPER MIDWEST BUT THERE WILL
LIKELY BE SEVERAL WEAK SHORT WAVE TROUGHS COMING ACROSS THE
REGION. THIS WILL RESULT IN SOME SMALL ON AND OFF RAIN CHANCES
STARTING WEDNESDAY NIGHT AND CONTINUING THROUGH THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1230 PM CDT SUN JUL 5 2015

VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING THEN SHOWERS AND
THUNDERSTORM MOVE IN MONDAY MORNING WITH MVFR/IFR CONDITIONS
POSSIBLE.

A COLD FRONT WILL APPROACH THE UPPER MISSISSIPPI RIVER VALLEY LATE
TONIGHT INTO MONDAY MORNING. WINDS INCREASE INTO THE 35 TO 45 KT
RANGE AT 1500 TO 2000FT LATE TONIGHT. WILL MAINTAIN LLWS IN THE
KLSE TAF STARTING AT 12Z AND PERSISTING THROUGH 15Z. SHOWERS AND
THUNDERSTORMS LOOK TO MOVE INTO THE REGION MONDAY MORNING
IMPACTING KRST FIRST. PLAN ON IFR CONDITIONS IN THE STORMS WITH
THE POTENTIAL TO SEE SOME GUSTY WINDS AS WELL. THE STORMS LOOK TO
CONTINUE THROUGH MONDAY MORNING AND COULD IMPACT KLSE IN THE 15Z
TO 18 TIMEFRAME...HOWEVER IT APPEARS THE HIGHER CHANCES FOR STORMS
WILL ARRIVE AT KLSE DURING THE EARLY AFTERNOON HOURS WITH IFR
CONDITIONS POSSIBLE. SOME OF THE STORMS COULD PRODUCE STRONG
WINDS...HEAVY RAINFALL...AND PERHAPS SOME HAIL.


&&

.HYDROLOGY...
ISSUED AT 302 PM CDT SUN JUL 5 2015

THE INCOMING STORM SYSTEM STILL LOOKS TO HAVE THE POTENTIAL TO
PRODUCE SOME LOCALLY HEAVY RAINS. THE PRECIPITABLE WATERS WILL
INCREASE INTO THE 2 TO 2.4 INCH RANGE WITH WARM CLOUD DEPTHS OF 4
TO 4.5 KM. THE STORMS COULD ALSO DO SOME TRAINING IF THE MOVEMENT
BECOMES SOUTHWEST TO NORTHEAST...BUT THE WHOLE SYSTEM LOOKS TO BE
PROGRESSIVE WHICH WILL LIMIT THE AMOUNT OF TIME THAT ANY TRAINING
COULD OCCUR. GENERAL QPF AMOUNTS LOOK TO BE IN THE THREE QUARTERS
TO 1.5 INCH RANGE...WHICH BY ITSELF IS NOT ENOUGH TO PRODUCE
FLOODING. HOWEVER...THE STORMS WILL BE EFFICIENT RAIN PRODUCERS
AND LIKELY HAVE SOME BRIEF HIGH RAINFALL RATES WHICH COULD PRODUCE
SOME VERY LOCALIZED PROBLEMS.

&&

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

$$

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


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