250
FXUS63 KARX 080519
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1219 AM CDT WED JUL 8 2026
KEY MESSAGES
- SHOWERS AND STORMS ARE LIKELY (60-80%) WEDNESDAY, PRIMARILY
DURING THE AFTERNOON INTO THE OVERNIGHT BRINGING HEAVY
RAINFALL. AMOUNTS OF 1 INCH OR MORE POSSIBLE (30-50%) WITH
LOCALIZED AMOUNTS OF 2-3 INCHES.
- STRONG TO SEVERE STORMS MAY ACCOMPANY THE HEAVY RAINFALL
WEDNESDAY. DAMAGING WIND GUSTS WILL BE THE PRIMARY THREAT.
- SEASONABLE TEMPERATURES ARE EXPECTED THROUGHOUT MUCH OF THE
WEEK WITH HIGHS IN THE LOW TO MID 80S BEFORE WARMING THROUGH
THE WEEKEND AND INTO NEXT WEEK.
DISCUSSION
ISSUED AT 156 PM CDT TUE JUL 7 2026
REST OF TODAY
FAIRLY QUIET CONDITIONS ARE EXPECTED TO LINGER THROUGHOUT THE
REMAINDER OF THE AFTERNOON AND INTO THIS EVENING AS WEAK UPPER
RIDGING REMAINS SITUATED ACROSS THE REGION. THERE DOES APPEAR TO
BE SOME LOW POTENTIAL FOR A STRAY SHOWER OR STORM MAINLY ALONG
AND NORTH OF I-90 AHEAD OF SUNSET GIVEN A FEW HOURS WHERE MLCAPE
REACHES 1000-1500 J/KG PER RAP/HRRR/RRFS SOUNDINGS. THE MAIN
UNCERTAINTY REGARDING THIS POTENTIAL IS THE LACK OF A
DEFINITIVE FORCING MECHANISM FOR CONVECTIVE INITIATION.
CURRENTLY THINKING ANY CONVECTIVE DEVELOPMENT SITS AT A 10-15%
CHANCE.
WEDNESDAY - THURSDAY: HEAVY RAIN AND STRONG TO SEVERE STORMS
MORE ZONAL FLOW TAKES HOLD LATE THIS EVENING INTO THE OVERNIGHT
HOURS, ALLOWING SEVERAL SHORTWAVES TO TRANSLATE EASTWARD AND
SPARK CONVECTIVE DEVELOPMENT ACROSS PORTIONS OF CENTRAL
MINNESOTA AND NORTHERN WISCONSIN. CAM GUIDANCE AND SHORT-RANGE
ENSEMBLES SUCH AS THE 07.12Z REFS/HREF SUGGEST THE BULK OF
CONVECTIVE ACTIVITY WILL REMAIN TO THE NORTH ALONG A SURFACE
BOUNDARY THAT CURRENTLY EXTENDS FROM SOUTH DAKOTA ACROSS
MINNESOTA AND INTO NORTHERN WISCONSIN AND ALONG WITH IT, THE
HEAVIEST RAINFALL. HOWEVER, TOWARDS THE MORNING HOURS, SHOWERS
AND STORMS SHOULD BEGIN TO MOVE INTO TAYLOR AND CLARK COUNTIES
(30-60%) BRINGING A PERIOD OF HEAVY RAINFALL.
THE AFOREMENTIONED BOUNDARY BEGINS TO SLIDE SOUTHEASTWARD
THROUGH THE WEDNESDAY AS ANOTHER LEADING TO SHOWERS AND STORMS
ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. HEAVY RAINFALL IS
EXPECTED TO CONTINUE ALONG THIS BOUNDARY GIVEN FAVORABLE PWATS
IN EXCESS OF 1.7 INCHES, ABOVE THE 90TH PERCENTILE OF
CLIMATOLOGY, AND WARM CLOUD DEPTHS OF 10-12KFT. BOUNDARY
RELATIVE FLOW IS SOMEWHAT PARALLEL RATHER THAN ORTHOGONAL SUCH
THAT THE RISK OF TRAINING IS SLIGHTLY REDUCED. THAT SAID, THERE
IS STILL SOME DECENT PROBABILITIES FOR AMOUNTS GREATER THAN 1
INCH OF RAIN IN THE 07.13Z NBM WHICH SITS AT 30-50%. THE 07.12Z
HREF/REFS 24HR LPMM ALSO SUGGEST SOME POCKETS OF 2-3 INCHES ARE
POSSIBLE ALONG AND NORTH OF I-90 WHICH WOULD LEAD TO SOME
FLOODING CONCERNS, ESPECIALLY OVER SOUTHEAST MINNESOTA WHERE THE
GREATEST RAINFALL AMOUNTS OCCURRED LAST WEEK. THERE IS ALSO
SOME FLOODING CONCERN FOR AREAS THAT SEE MULTIPLE ROUNDS OF RAIN
SUCH AS NORTH-CENTRAL WISCONSIN. THAT SAID, THE PROGRESSIVE
NATURE OF THE BOUNDARY SHOULD HELP KEEP MITIGATE SOME OF THE
FLOODING RISK.
ON TOP OF THE HEAVY RAIN THREAT, STORMS THAT DEVELOP WEDNESDAY
MAY BECOME STRONG TO SEVERE. MLCAPE ON THE ORDER OF 1500-2500
J/KG WOULD SUPPORT STRONGER UPDRAFTS, ALTHOUGH SHEAR IS THE
BIGGEST UNCERTAINTY REGARDING ORGANIZED CONVECTION. THERE IS A
FEW HOUR WINDOW WHERE STRONGER 500HPA FLOW ALOFT ELONGATES
HODOGRAPHS IN THE 3-6KM LAYER, RESULTING IN SHEAR VALUES OF
30-35KTS WHICH WOULD SUPPORT SOME SUPERCELLULAR STRUCTURES IN
STORMS THAT INITIALLY DEVELOP. THIS WOULD RESULT IN A SHORT
PERIOD WHERE HAIL COULD POSE A THREAT, BUT GIVEN THE PREVIOUSLY
DISCUSSED WARM CLOUD DEPTHS AND A WBZ HEIGHT ABOVE 10KFT, HAIL
IS A LOWER END THREAT. HOWEVER, THIS UPPER FLOW QUICKLY
DIMINISHES WITH TIME RESULTING IN WIND SHEAR BEING CONFINED TO
THE 0-3KM. THIS WOULD SUGGEST THE SEVERE THREAT WOULD
TRANSITION TO DAMAGING WINDS AS COLD POOL DEVELOPMENT AND
UPSCALE GROWTH TO MORE OF A LINEAR MODE OCCURS.
FRIDAY - EARLY NEXT WEEK: WARMER TEMPERATURES RETURN
OVER THE WEEKEND, MID TO UPPER LEVEL RIDGING BEGINS TO BUILD
ACROSS THE UNITED STATES WHICH IS NOTED IN MOST/ALL OF THE
DETERMINISTIC AND ENSEMBLE GUIDANCE. HEIGHTS ASSOCIATED WITH
THIS RIDGE ARE EXPECTED TO BE FAIRLY IMPRESSIVE, REACHING
594-600DAM AT 500HPA, WHICH THE 07.00Z NAEFS HIGHLIGHTS AS NEAR
OR EXCEEDING THE MAXIMUM HEIGHTS WITHIN CLIMATOLOGY. SURFACE
TEMPERATURES TREND WARMER THIS WEEKEND INTO NEXT WEEK IN
RESPONSE TO THESE RISING HEIGHTS. THERE'S STILL QUITE A BIT OF
SPREAD WITHIN THE VARIOUS ENSEMBLE SUITES REGARDING WHAT THE
TEMPERATURES WILL ULTIMATELY BE, BUT INTERQUARTILE SPREADS
SUGGEST HIGHS IN THE UPPER 80S ARE FAVORED, BUT POSSIBLY REACH
INTO THE LOW 90S. DEWPOINT TEMPERATURES ALSO INCREASE DURING
THIS PERIOD AS THE 07.07Z NBM SUGGESTS A 30-60% PROBABILITY TO
EXCEED 70 DEGREES HIGHEST OVER NORTHEAST IOWA, TRANSLATING TO
APPARENT TEMPERATURES IN THE 90S. WILL NEED TO CONTINUE
MONITORING TRENDS, BUT A RETURN TO WARM AND MUGGY CONDITIONS
LOOKS TO BE ON THE HORIZON.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1219 AM CDT WED JUL 8 2026
VFR CONDITIONS THROUGHOUT MUCH OF THE OVERNIGHT GIVE WAY TO
SHOWER AND STORM CONCERNS THROUGHOUT THE MORNING THROUGH
EVENING HOURS FOR WEDNESDAY. WILL HAVE TO WATCH TO SEE IF STORMS
IN NORTH-CENTRAL WI SHOWN IN THE CAMS EARLY THIS MORNING COULD
MAKE THEIR WAY TO THE I-90 CORRIDOR (UNDER 20% CHANCE), HOWEVER
THE BULK OF THE CAMS KEEP THE I-90 CORRIDOR STORM FREE UNTIL
AFTERNOON. MVFR TO IFR REDUCTIONS ARE TO BE EXPECTED WITH ANY
STORMS AND A FEW STORMS MAY BE STRONG TO SEVERE WITH GUSTY TO
LOCALLY DAMAGING WIND GUSTS. CIGS WILL REMAIN PREDOMINANTLY VFR
OUTSIDE OF ANY STORMS BUT WILL LOWER TO LOW-VFR AND PERHAPS MVFR
NORTH OF I-90 TOWARDS 06Z THURSDAY. WINDS WILL REMAIN FROM THE
SOUTHWEST THROUGHOUT MUCH OF THE DAY AT AROUND 6-12 KTS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FALKINHAM
AVIATION...NAYLOR
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