204
FXUS63 KMKX 021102 AAA
AFDMKX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
602 AM CDT WED SEP 2 2026
KEY MESSAGES
- UNSEASONABLY WARM AND MUGGY CONDITIONS CONTINUE THROUGH THE
END OF THE WORK WEEK. UPPER 90S TO NEAR 100 DEGREE HEAT
INDICES WILL BE POSSIBLE DAILY IN AREAS EXPERIENCING AMPLE
SUNSHINE, ESPECIALLY TODAY.
- OCCASIONAL STORM CHANCES CONTINUE INTO THE BEGINNING OF THE
WEEKEND, WITH PLENTY OF DRY PERIODS IN BETWEEN. SOME STORMS
COULD BE ON THE STRONGER SIDE.
UPDATE
ISSUED 602 AM CDT WED SEP 2 2026
MAINLY DRY WEATHER IS EXPECTED THIS MORNING, WITH A NEARLY
STALLED FRONTAL BOUNDARY JUST TO THE NORTHWEST. THIS BOUNDARY
MAY SAG INTO THE NORTHERN FORECAST AREA BY AFTERNOON, WITH A FEW
SHOWERS AND STORMS POSSIBLE ALONG THE BOUNDARY DURING THE
AFTERNOON AND INTO THE EVENING. THE AIRMASS SOUTH OF THIS FRONT
WILL BE LARGELY THE SAME AS YESTERDAY, VERY WARM AND HUMID FOR
EARLY SEPTEMBER. MODELS WERE LARGELY TOO LOW WITH DEWPOINTS
YESTERDAY AND THAT MAY BE THE CASE AGAIN TODAY. WILL MONITOR
DEWPOINT TRENDS THIS MORNING AND ADJUST THE FORECAST AS NEEDED,
AS HEAT INDICES COULD EXCEED 100 AGAIN IN THE SOUTH. GIVEN THE
BOUNDARY SAGGING INTO THE AREA ALONG WITH A LOT OF HIGH CLOUDS,
OPTED TO HOLD OFF ON ANY HEAT HEADLINES FOR NOW.
DDV
SHORT TERM
ISSUED 1240 AM CDT WED SEP 2 2026
TODAY AND TONIGHT:
ONGOING CONVECTION CONTINUES TO ORGANIZE ALONG THE MN/IA BORDER,
WITH A NORTH-SOUTH MUCAPE GRADIENT SPANNING FROM THERE ALL THE
WAY EAST THROUGH SOUTHERN WI. OUR UNDERSTANDING IS THAT THIS
CONVECTION WILL TRACK EAST ALONG THIS INSTABILITY GRADIENT,
LIKELY MOVING INTO PORTIONS OF CENTRAL AND EAST-CENTRAL WI FROM
3-7 AM THIS MORNING, MAINLY ALONG AND NORTH OF WI STATE TRUNK
HIGHWAY 60 (THOUGH SOME LESS ORGANIZED CELLS COULD SPILL FURTHER
SOUTH). ISOLATED STRONG STORM CELLS HAVE ALREADY FORMED ACROSS
THE NORTHERN CWA OUT AHEAD OF IT ALONG THE AFOREMENTIONED
GRADIENT.
THE LLJ WILL UNDERGO NOCTURNAL STRENGTHENING, ANGLING
FROM SW TO NE ACROSS IA EARLY THIS MORNING AND FEEDING INTO THE
APPROACHING MCS AS IT TRACKS EAST TOWARDS THE DELLS. FURTHER
EAST FROM THERE, THE LLJ LOSES ITS EDGE, BUT THE MUCAPE REMAINS
IN PLACE (AND EVEN SPREADS FURTHER NORTH IN EASTERN WI). MOST
CAMS ALLOW THE MCS TO EVOLVE INTO AN MCV (DEVELOP A COMMA HEAD)
AS IT TRACKS FURTHER EAST, AND THOUGH IT COULD BEGIN TO DECAY IT
OUGHT TO HAVE PLENTY OF SYSTEM-SCALE MOMENTUM.
WE WOULD NOT BE SURPRISED TO SEE A FEW STRONG OR EVEN SEVERE
STORMS WITH THIS SYSTEM (LEVEL 2 OUT OF 5 SEVERE RISK), WITH THE
MAIN THREAT BEING DAMAGING WIND GUSTS. PRIMARY THREAT AREA IS
ALONG AND NORTH OF HWY 60 IN CENTRAL AND EAST-CENTRAL WI, WITH A
PARTICULAR EMPHASIS ON THOSE AREAS NORTH AND WEST OF MADISON. MCVS
HAVE A HABIT OF MODIFYING THE ENVIRONMENT AROUND THEM, SO STAY
TUNED IN CASE ANY OF THIS CHANGES!
THE MORNING STORM COMPLEX WILL LIKELY LEAVE AN EFFECTIVE OUTFLOW
BOUNDARY STRETCHING EAST-WEST ACROSS THE CWA, WHICH COULD SERVE AS
A FOCAL POINT FOR SOME DISORGANIZED AFTERNOON SHOWERS AND
THUNDERSTORMS, PERHAPS REMINISCENT OF WHAT WE SAW THIS PAST
AFTERNOON. THE CAPE WILL BE STRONG, BUT NO FEATURES WILL BE
PRESENT FOR SUBSTANTIAL STORM ORGANIZATION. THIS WILL CONTINUE TO
BE THE STATUS QUO INTO THE EVENING, WITH BETTER CHANCES FOR STORM
INITIATION AND COVERAGE LATE TONIGHT INTO THURSDAY AM (CONTINUED
IN THE LONG-TERM DISCUSSION).
SHEPPARD
LONG TERM
ISSUED 1240 AM CDT WED SEP 2 2026
THURSDAY THROUGH TUESDAY:
SYNOPSIS: WARM, HUMID, AND UNSETTLED WEATHER IS EXPECTED TO REMAIN
IN PLACE THROUGH MUCH OF THE EXTENDED FORECAST, WITH A SLIGHT
SIGNAL ON SOME ECMWF/GEFS ENSEMBLE PLOTS FOR A COOLING TREND
(PARTIAL BREAKDOWN OF THE UPPER RIDGE) LATE THIS WEEKEND INTO
EARLY NEXT WEEK. THE CREST OF THE UPPER RIDGE SHOULD REMAIN OVER
OR JUST NORTH OF THE STATE, WITH OCCASIONAL RIPPLES IN THE
PATTERN YIELDING CHANCES FOR SHOWERS AND THUNDERSTORMS.
THURSDAY AM: THOUGH THE NOSE OF THE LLJ IS RATHER BROAD ACROSS
SOUTHERN WI PREDAWN THROUGH LATE THURSDAY MORNING, RIPPLES IN THE
700-500MB FLOW COULD AID IN SOME CONVECTIVE INITIATION, AND IT'S
SAFE TO SAY THERE IS A CHANCE (35-60%) FOR THUNDERSTORMS ACROSS
THE CWA. WIND SHEAR (30-40KT) IS SUFFICIENT FOR SOME STORM
ORGANIZATION IF THE UPDRAFTS CAN REMAIN ROBUST IN THE FACE OF
~10 DEG-C 700MB TEMPS (WOULD NEED STRONG FORCING TO KICK-START
AN MCS).
THURSDAY PM: SOME MODELS ALLOW THE MAIN SURFACE FRONTAL BOUNDARY
(STALLED EAST-WEST OVER THE UPPER GREAT LAKES) TO FIRE CONVECTION
THURSDAY AFTERNOON OVER THE NORTHERN HALF OF WI, THEN PLUNGE IT
SOUTH INTO THE INSTABILITY PLUME (SOUTHERN HALF) LATER IN THE
DAY. THOUGH WE'VE GOT SHOWER AND STORM CHANCES (10-35%) TO
ACCOUNT FOR THIS, WE'D HAVE TO SEE MEANINGFUL FORCING FOR ASCENT
THIS FAR SOUTH IN ORDER TO BOOST OUR PRECIP CHANCES ANY HIGHER,
AND RIGHT NOW, WE'RE JUST NOT SEEING IT.
THURSDAY NIGHT INTO FRIDAY AM: A GOOD FRACTION OF AVAILABLE GUIDANCE
HINTS AT A 500MB SHORTWAVE DESCENDING THE EASTERN CREST OF THE RIDGE
THURSDAY NIGHT INTO FRIDAY MORNING, YIELDING A ROUND OF (POTENTIALLY
ORGANIZED) CONVECTION ACROSS THE STATE. EXACT TIMING IS UNCERTAIN,
BUT FOR NOW THIS DOES YIELD THE STRONGEST WIND SHEAR OF ANY FEATURE
ON THE SCOPE (OVER 40 KT). IF THIS PHASES WELL WITH LULLS / RECOVERY
FROM THE PRIOR ROUND OR WITH THE THURSDAY NIGHT LLJ, THINGS COULD
GET INTERESTING.
SHEPPARD
AVIATION
ISSUED 602 AM CDT WED SEP 2 2026
MAINLY DRY WEATHER IS EXPECTED THIS MORNING, WITH A NEARLY
STALLED FRONTAL BOUNDARY JUST TO THE NORTHWEST. THIS BOUNDARY
MAY SAG INTO THE NORTHERN FORECAST AREA BY AFTERNOON, WITH A FEW
SHOWERS AND STORMS POSSIBLE ALONG THE BOUNDARY DURING THE
AFTERNOON AND INTO THE EVENING. THE CHANCE FOR STORMS WILL
LINGER OVERNIGHT INTO THURSDAY MORNING, THOUGH CONFIDENCE IN THE
TIMING/LOCATION OF ANY STORMS REMAINS ON THE LOWER END.
VFR CONDITIONS WILL PERSIST TODAY INTO THURSDAY, OUTSIDE OF
POTENTIAL LOWER CEILINGS AND VISIBILITIES WITHIN THUNDERSTORMS.
LIGHT AND VARIABLE WINDS EARLY THIS MORNING WILL BECOME LARGELY
SOUTHWEST TO WEST 5-10 KNOTS BY MID-AFTERNOON. A LAKE BREEZE
MAY RESULT IN WINDS BECOMING EAST TO SOUTHEAST NEAR THE LAKE BY
AFTERNOON. LIGHT AND VARIABLE WINDS WILL THEN RETURN TO SOUTHERN
WISCONSIN TONIGHT.
DDV
MARINE
ISSUED 1240 AM CDT WED SEP 2 2026
LIGHT WINDS COMBINED WITH A LINGERING HUMID AIR MASS WILL
SUPPORT AREAS OF FOG DEVELOPMENT ACROSS LAKE MICHIGAN EARLY THIS
MORNING, MAINLY OVER NORTHERN AND WESTERN PORTIONS OF THE LAKE.
OFF AND ON ROUNDS OF THUNDERSTORMS EXPECTED TODAY THROUGH
THURSDAY AS A STALLED FRONT LINGERS IN THE REGION. WIDESPREAD
SEVERE WEATHER ISN'T EXPECTED OVER THE WATERS, THOUGH AN
ISOLATED STRONGER CELL WITH HAIL AND GUSTY WINDS CAN'T BE
ENTIRELY RULED OUT.
LIGHT AND VARIABLE WINDS TODAY WILL SHIFT EAST-NORTHEASTERLY
THROUGH THE SECOND HALF OF THE WEEK AS 30.1 INCH HIGH PRESSURE
BUILDS OVER THE HUDSON BAY AND BROAD, 29.6 INCH LOW PRESSURE
MOVES INTO THE NORTHERN GREAT PLAINS. AN UNSETTLED PATTERN
FEATURING MULTIPLE ADDITIONAL THUNDERSTORM CHANCES WILL CONTINUE
THROUGH AT LEAST FRIDAY NIGHT.
SHEPPARD
MKX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
LM...NONE.
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