185
FXUS63 KARX 290640
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
140 AM CDT SUN JUN 29 2025
KEY MESSAGES
- A FEW SHOWERS AND STORMS LINGER THIS MORNING WITH SCATTERED
THUNDERSTORMS (40-50% COVERAGE) REDEVELOPING IN THE AFTERNOON
AND EVENING, SOME OF WHICH COULD NEAR SEVERE LEVELS.
- ADDITIONAL THREAT FOR STORMS MONDAY AND MIDWEEK, BUT
CONFIDENCE IS LOW (20-30%) IN THE COVERAGE AND IMPACTS FROM
THESE STORMS.
- WARM TODAY WITH SEASONAL TEMPERATURES FOR THE START OF THE
WEEK, SLOWLY WARMING AGAIN TOWARDS THE END OF THE WEEK.
DISCUSSION
ISSUED AT 140 AM CDT SUN JUN 29 2025
TODAY/TONIGHT: STORM DETAILS
ONGOING LINEAR CONVECTION ACROSS MINNESOTA IS GRADUALLY WINDING
DOWN EARLY THIS MORNING AS IT STARTS TO SHIFT OUT OF FAVORED
DEEP SHEAR REGIME, RESULTING IN THE STORMS BECOMING OUTFLOW
DOMINANT. NEVERTHELESS, FORECAST PROFILES FROM THE HRRR/RAP
DENOTE LARGE VALUES OF MUCAPE OVERNIGHT WITH RELATIVELY LOW
INHIBITION VALUES FOR PARCELS LAUNCHED AROUND 800 MB AS FAR
EAST AS WESTERN WISCONSIN. IF THE OUTFLOW BOUNDARY MANAGES TO
BREAK THIS CAP, WE COULD SEE RENEWED DEVELOPMENT AND THE
POTENTIAL FOR GUSTY WINDS AND SMALL HAIL, BUT COMPLEX
HODOGRAPHS LIMIT THE ORGANIZATION POTENTIAL FOR ANY INDIVIDUAL
UPDRAFT.
THE OUTFLOW AND CONVECTIVE DEBRIS LEFT OVER FROM OUR OVERNIGHT
CONVECTION (SURPRISE!) RESULTS IN DEGRADED CONFIDENCE IN HOW AND
WHERE CONVECTIVE INITIATION UNFOLDS LATER TODAY. WHAT
CONSTITUTES A SURFACE COLD FRONT (MORE OF A BROAD WIND SHIFT VS.
A TRUE FRONT) MIGRATES TOWARDS THE REGION THIS AFTERNOON FROM
THE DAKOTAS. THIS FRONT WILL BE APPROACHING THE REGION TOWARDS
THE MID TO LATE AFTERNOON, WITH CONVECTION LIKELY INITIATING
BOTH ALONG THE BOUNDARY AND AHEAD OF IT IN ANY LEFTOVER
DIFFERENTIAL HEATING ZONES COURTESY OF OUR MORNING STORMS. THIS
MAKES IT VERY DIFFICULT TO PIN DOWN THE EXACT PLACEMENT OF
CONVECTION AT ANY GIVEN TIME, THOUGH UPSCALE GROWTH INTO SOME
CELL CLUSTERS IS ANTICIPATED GIVEN THE COMPLEX HODOGRAPH
PROFILES. AS THE SURFACE FRONT FINALLY MOVES THROUGH IN THE
EVENING/OVERNIGHT, WE MAY SEE ENOUGH LIFT TO KEEP SOME SHOWERS
AND STORMS GOING THROUGH THE NIGHT, MAINLY SOUTH OF I-90.
THE SEVERE POTENTIAL FOR THIS AFTERNOON RESTS ON ROBUST BUT
SHORT-LIVED UPDRAFTS GETTING STRONG ENOUGH TO SUPPORT BRIEF
PERIODS OF LOW END SEVERE WIND (60 MPH) OR HAIL (AROUND 1" IN
DIAMETER). DESPITE MLCAPE VALUES NEARING 2000 J/KG, THE
AFOREMENTIONED COMPLEX AND COMPACT HODOGRAPHS WILL LIMIT THE
LONGEVITY OF THE UPDRAFTS AND RESULT IN STORMS QUICKLY GETTING
UNDERCUT BY THEIR OWN OUTFLOW. AS WE MOVE THROUGH THE EVENING
AND NIGHT, THE SEVERE THREAT WANES WITH THE INCREASING IN
BOUNDARY LAYER STABILIZATION.
UPCOMING WEEK: PERIODIC, LOW CONFIDENCE RISK OF STORMS
WHILE THERE ARE MULTIPLE PERIODS OF STORMS IN THE FORECAST FOR
THE UPCOMING WEEK, THE OVERALL PATTERN IS MUCH DRIER THAN WHAT
WE SAW LAST WEEK. FOR MONDAY, A SHARPENING UPPER TROPOSPHERIC
TROUGH DIGS SOUTH INTO MINNESOTA, WITH THERE BEING ENOUGH
KINEMATIC SUPPORT AND STEEPENING LOW-LEVEL LAPSE RATES TO
SUPPORT AT LEAST SOME CONVECTION--THOUGH THE STRENGTH OF THE
CELLS REMAINS IN QUESTION GIVEN SOME SIGNAL FOR POORER MID-
LEVEL LAPSE RATES STUNTING THE VERTICAL GROWTH OF THE UPDRAFTS.
TUESDAY SHOULD SEE A BREAK IN THE STORMS AS SHORTWAVE RIDGING
PASSES THROUGH. FOR MIDWEEK AND INTO THE END OF THE WEEK,
NORTHWESTERLY FLOW DOWNSTREAM OF A MERIDIONAL HIGH PLAINS RIDGE
RESULTS IN LOW CONFIDENCE CHANCES FOR CONVECTION, THE DETAILS
OF WHICH ARE DIFFICULT TO RESOLVE AT THIS RANGE.
AFTER ANOTHER WARM DAY TODAY, COOLER AIR SETTLES IN FOR THE
START OF THE WEEK AND KEEPS TEMPERATURES NEAR SEASONAL NORMS. AS
RETURN FLOW INCREASES FOR MID TO LATE WEEK, INCREASING LOWER
TROPOSPHERIC THETA-E AIR WILL BOOST TEMPERATURES AND DEWPOINTS
BACK INTO THE WARM AND MUGGY REALM.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1215 AM CDT SUN JUN 29 2025
PREDOMINANTLY VFR CONDITIONS ARE FORECAST FOR THE TAF PERIOD
OUTSIDE OF LOCALIZED POCKETS OF RESTRICTIONS WITHIN SCATTERED
SHOWERS AND THUNDERSTORMS IN THE EARLY MORNING HOURS AND AGAIN
FROM THE MID-AFTERNOON INTO THE EARLY EVENING. WINDS WILL BE
MAINLY FROM THE SOUTH OVERNIGHT, VEERING TO THE SOUTHWEST DURING
THE DAY AT AROUND 10 KTS BEFORE BECOMING LIGHT FROM THE WEST IN
THE EVENING.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...SKOW
AVIATION...SKOW
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