Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 011143
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
643 AM CDT SAT AUG 1 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT SAT AUG 1 2015

AS NORTHWEST UPPER FLOW CONTINUES...MAIN CHALLENGE IN SHORT TERM IS
EXTENT OF CONVECTION TONIGHT...INCLUDING TRACK OF ANY CONVECTIVE
SYSTEMS AND OVERALL STRENGTH. AREA REMAINS BETWEEN FASTER NORTHWEST
FLOW TO THE NORTH AND HIGHER INSTABILITY TO THE SOUTHWEST BUT THIS
BORDER AREA WILL COME INTO PLAY NEXT 24 HOURS IT APPEARS.

RELATIVELY SMALL AREA OF HIGHER THETA-E AND RELATED PRECIPITABLE
WATER VALUES ACROSS SOUTHEAST MINNESOTA EARLY THIS MORNING...
COMBINED WITH SOME CONVERGENCE...HAS LED TO DEVELOPMENT OF MID LAYER
CLOUDS AND WIDELY SCATTERED CONVECTION EARLY THIS MORNING BETWEEN
KLSE AND KMSP. COVERAGE SHOULD REMAIN MINOR AS CELLS MOVE SOUTHEAST
IN MID LEVEL FLOW...BUT HAVE INTRODUCED SCATTERED ACTIVITY INTO THE
DAYBREAK HOURS.

WHILE MOST OF THE DAY WILL REMAIN QUIET...FOCUS SHIFTS ON TONIGHT.
SHORT WAVE MOVING OUT OF MONTANA THIS MORNING WILL DRIFT SOUTHEAST
INTO THE CORNBELT REGION TODAY. RESPONSE TO THIS WILL BE IN THE FORM
OF STRENGTHENING LOW LEVEL JET AND MOISTURE TRANSPORT THIS EVENING
TO THE SOUTHWEST...WHICH WILL LEAD TO MORE DEFINED WARM FRONT.
WHILE STORM DEVELOPMENT IS EXPECTED TO THE WEST AND SOUTHWEST
INITIALLY...QUESTIONS ABOUND ON WHERE THAT CONVECTION WILL TRACK
GIVEN FLOW AND WARM FRONT LOCATION. INITIAL ACTIVITY COULD DIVE
SOUTHEAST AND MISS MOST OF AREA...FAVORING HIGHER MIXED LAYER CAPE
VALUES TO THE SOUTHWEST...AS MODELS CONTINUE TO OVERDUE EXTENT OF
NORTHEAST PUSH OF HIGHER SURFACE DEW POINTS. 01.00Z NAM CERTAINLY
FAVORS THIS SOLUTION. AND IF THAT HAPPENS...HOW MUCH CONVECTION
WOULD FIRE NORTH OF THERE IS BIG QUESTION AS SOME MESOSCALE MODELS
ADVERTISE.

PATH OF MCS WILL BE KEY THIS EVENING...ESPECIALLY NEAR WARM FRONT
GIVEN EXPECTED HIGHER LOW LEVEL SHEAR. WILL CONTINUE TO HONOR DAY 1
SLIGHT RISK BY STORM PREDICTION CENTER BUT KEEP PRODUCT SUITE IN
CONDITIONAL...LOW CONFIDENCE MODE UNTIL STORM TRACK AND BOUNDARY
LOCATION CAN BE BETTER DETERMINED. STORMS COULD BEGIN TO IMPACT
WESTERN AREAS AROUND MID EVENING /02.02Z/ AND THEN MIGRATE THROUGH
OVERNIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 300 AM CDT SAT AUG 1 2015

SUNDAY SETUP WILL AT LEAST PARTIALLY BE DETERMINED BY HOW TONIGHT
PLAYS OUT. STRONGER SHORT WAVE TROUGH IN NORTHWEST FLOW WILL DIVE
INTO WESTERN GREAT LAKES BY LATE SUNDAY AND DEPENDING ON WHERE
BOUNDARY IS LINGERING...COULD SEE REDEVELOPMENT. APPEARS BEST LOW
LEVEL RESPONSE TO WORK ON FRONT WILL PUSH INTO SOUTHERN WISCONSIN
AND NEIGHBORING AREAS. WE COULD SEE SOME INITIAL DEVELOPMENT IN
EASTERN AND SOUTHERN AREAS BEFORE CONVECTION QUICKLY MOVES OFF... OR
ACTIVITY COULD EVEN FLARE UP JUST SOUTHEAST OF AREA WHERE HIGHER
INSTABILITY LEVELS LIKELY TO BE ESTABLISHED.

RAIN THREAT QUICKLY EXITS SUNDAY EVENING AS A MORE QUIET NORTHWEST
REGIME FLOW RETURNS FOR EARLY PART OF WEEK. COOLER TEMPERATURES LOOK
ON TRACK BEHIND SUNDAYS WAVE AS WELL.

BY MID WEEK...MORE SHORT WAVE TROUGHS CROSSING FLATTENING UPPER
RIDGE TO THE WEST WILL BRING RAIN THREATS BACK INTO AREA. COOLER AND
DRIER FLOW WOULD LIKELY LIMIT ANY SEVERE WEATHER POTENTIAL WITH THAT
ACTIVITY BUT WILL HAVE TO WAIT AND SEE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 643 AM CDT SAT AUG 1 2015

AN UPPER LEVEL TROUGH AND ASSOCIATED ISOLATED SHOWER ACTIVITY WILL
MOVE SOUTHEAST OF THE KRST/KLSE TAF SITES THIS MORNING BY 15Z.
PLAN ON VFR CONDITIONS THROUGH TODAY AS A RIDGE OF HIGH PRESSURE
DRIFTS EAST ACROSS THE REGION. ATTENTION THEN TURNS TO INCOMING
LOW PRESSURE FROM THE NORTHERN PLAINS TONIGHT. THIS IS EXPECTED TO
SPREAD SCATTERED SHRA/TS INTO THE AREA IN THE 02-03Z TIME FRAME.
HARD TO PINPOINT EXACT COVERAGE OF THE STORM ACTIVITY AND
PROXIMITY TO THE TAF SITES SO WENT WITH VCTS FOR NOW. THERE IS A
CHANCE A FEW OF THE STORMS COULD BECOME STRONG TO SEVERE WITH
LARGE HAIL AND DAMAGING WIND BEING THE MAIN THREAT.
OTHERWISE...LOOKS LIKE VFR CLOUD CONDITIONS SHOULD PREVAIL.

&&

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

$$

SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...DAS


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