847
FXUS63 KMKX 312036
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
336 PM CDT MON AUG 31 2026
KEY MESSAGES
- HEAT & HUMIDITY CONTINUES THROUGH MIDWEEK. AFTERNOON HEAT
INDICES IN THE LOW-MID 90S EXPECTED EACH DAY THROUGH
WEDNESDAY, WITH UPPER 90S TO NEAR TRIPLE DIGITS POSSIBLE IN
AREAS EXPERIENCING MORE SUNSHINE. WARM TEMPERATURES LINGER
INTO THE WEEKEND, WITH HEAT INDEX VALUES IN THE UPPER 80S TO
LOW 90S THURSDAY THROUGH SUNDAY.
- ISOLATED THUNDERSTORMS POSSIBLE THIS AFTERNOON AND EVENING AND
AGAIN TUESDAY AFTERNOON AND EVENING.
- AREAS OF FOG WITH VISIBILITIES AS LOW AS 2 MILES ARE EXPECTED
OVERNIGHT TONIGHT, WITH POTENTIAL FOR PATCHY DENSE FOG IN LOW
LYING AREAS.
- SCATTERED STORM CHANCES RETURN LATE TUESDAY NIGHT INTO
WEDNESDAY MORNING, ESPECIALLY FOR CENTRAL WISCONSIN.
ADDITIONAL SCATTERED STORMS WILL OCCUR ON AND OFF WEDNESDAY
THROUGH FRIDAY.
SHORT TERM
ISSUED 336 PM CDT MON AUG 31 2026
TONIGHT THROUGH TUESDAY NIGHT:
A STRONG CAPPING INVERSION WITH 200-250 J/KG OF CIN HAS
PREVENTED SCATTERED THUNDERSTORMS FROM NUDGING OVER THE BORDER
INTO WISCONSIN THIS AFTERNOON. AN ISOLATED THUNDERSTORM IS STILL
POSSIBLE, BUT BECOMING LESS LIKELY. ISOLATED TO SCATTERED
SHOWERS ARE EXPECTED THROUGH THIS EVENING, ENDING AROUND SUNSET.
HIGHS IN THE MID 80S ARE EXPECTED, WITH HEAT INDEX VALUES IN
THE LOW 90S.
AFTER SUNSET, TEMPERATURES WILL FALL INTO THE LOW 70S AND WINDS
CALM AS A FRONTAL FEATURE STALLS OVER CENTRAL WISCONSIN. WITH
DEWPOINTS ALSO IN THE UPPER 60S TO LOW 70S, WIDESPREAD FOG IS
EXPECTED, WITH PATCHY DENSE FOG POSSIBLE IN LOW-LYING AREAS.
FOG IS EXPECTED TO BURN OFF SHORTLY AFTER SUNRISE ON TUESDAY AS
SOUTHWESTERLY WINDS INCREASE AGAIN. WITH WAA THROUGH ALL LEVELS
AND A MORNING BREAK IN THE CLOUD COVER, EXPECTING HIGH
TEMPERATURES TUESDAY TO REACH THE UPPER 80S TO 90 DEGREES. HEAT
INDEX VALUES ARE EXPECTED TO BE IN THE MID 90S IN CENTRAL
WISCONSIN WHERE MORE CLOUD COVER PERSISTS, AND IN THE UPPER 90S
FARTHER SOUTH. NEAR THE WI/IL BORDER, HEAT INDEX VALUES MAY
BRIEFLY REACH 100 DEGREES.
TUESDAY AFTERNOON INTO TUESDAY EVENING, AN ADDITIONAL PERIOD OF
ISOLATED TO SCATTERED THUNDERSTORMS IS POSSIBLE (20-30% CHANCES).
EXPECTING LIGHTNING TO BE THE PRIMARY THREAT, BUT CANNOT RULE
OUT AN ISOLATED STORM BECOMING SEVERE. WITH MUCAPE AROUND 2500
J/KG AND BULK SHEAR OF 35 TO 40 KT. A CAP REMAINS IN PLACE,
ALBEIT WEAKER (APPROXIMATELY 100 J/KG OF CIN), BUT A STRONG
TRIGGER IS LACKING FOR ADEQUATELY ORGANIZED STORMS. MAIN TRIGGER
WILL BE BROAD WAA ALOFT, WHICH WOULD LEND CREDENCE TO MORE OF A
SCATTERED THUNDERSTORM THREAT THAN AN ORGANIZED SEVERE THREAT.
LATE TUESDAY NIGHT INTO WEDNESDAY, AN 850 LLJ NOSES INTO CENTRAL
WISCONSIN WHERE THE WEAK FRONTAL BOUNDARY LINGERS, BRINGING
MORE CONFIDENCE FOR SCATTERED STORMS, BUT STILL LOW CONFIDENCE
FOR SEVERE ACTIVITY (20-40% CHANCES).
MH
LONG TERM
ISSUED 336 PM CDT MON AUG 31 2026
WEDNESDAY THROUGH MONDAY:
WISCONSIN REMAINS ON THE NORTHERN EDGE OF 500 MB RIDGING THROUGH
THE END OF THE WORK WEEK, WITH CHANCES FOR CONVECTION/RIDGE
RIDING MCSS THROUGH FRIDAY AND LINGERING HIGH HEAT AND HUMIDITY
THROUGH THURSDAY. INDIVIDUAL 500 MB SHORTWAVES AND LLJS WILL BE
THE DRIVING FORCE FOR STORMS THROUGH THE WEEK, WITH EXACT
TIMING AND PLACEMENT LIKELY NOT BECOMING CLEAR UNTIL 24 HOURS
FROM THE EACH EVENT. CURRENTLY, HIGHEST CONFIDENCE IN WIDESPREAD
STORM DEVELOPMENT FOR SOUTHERN WISCONSIN IS WEDNESDAY NIGHT
INTO THURSDAY, AS BROAD LOW PRESSURE DEVELOPS IN THE CENTRAL
PLAINS AND BRINGS A STRONGER, MORE FOCUSED LLJ TO EASTERN IOWA
AND SOUTHWESTERN WISCONSIN. THIS WOULD SUPPORT A SEVERE THREAT
DUE TO THE ENHANCED CAPE, MOISTURE, AND MORE FOCUSED TRIGGER AND
TEND TO LIKE THE NBM 50-70% POPS GOING INTO THURSDAY MORNING.
AS LOW PRESSURE DEEPENS IN THE NORTHEAST U.S. ON FRIDAY, HIGH
PRESSURE BUILDS INTO ONTARIO, BRINGING DRIER, NORTHEASTERLY FLOW
TO THE GREAT LAKES AND BRINGING A RETURN TO DRIER CONDITIONS AND
MORE SEASONABLE TEMPERATURES FOR THE WEEKEND INTO MONDAY (HIGHS
IN THE LOW 80S).
MH
AVIATION
ISSUED 336 PM CDT MON AUG 31 2026
VFR CONDITIONS WILL PREVAIL THROUGH THE REMAINDER OF TODAY, WITH
CEILINGS AROUND 8000 FT. UNDERNEATH ISOLATED STORMS, EXPECT
CEILINGS AROUND 5000 FT AND BRIEFLY LOWERED VISIBILITIES. A FEW
GUSTS UP TO 35 KT POSSIBLE DIRECTLY UNDER STRONGER STORMS, BUT
THESE LOOK TO STAY NEAR THE WI/IL BORDER. STORMS WILL END AROUND
SUNSET. OVERNIGHT, EXPECTING MAINLY DRY CONDITIONS TO PREVAIL
AND WINDS TO BECOME NEAR CALM. VERY HIGH HUMIDITY WILL LEAD TO
AREAS OF FOG WITH MVFR VISIBILITY ACROSS MUCH OF SOUTHERN
WISCONSIN. A FEW LOW LYING AREAS MAY SEE PATCHY DENSE FOG. FOG
WILL BURN OFF SHORTLY AFTER SUNRISE TUESDAY AS SOUTHWEST WINDS
INCREASE ONCE AGAIN. VFR CONDITIONS ARE THEN EXPECTED THROUGHOUT
TUESDAY.
MH
MARINE
ISSUED 336 PM CDT MON AUG 31 2026
LOW PRESSURE OF 29.5 INCHES OVER THE CANADIAN PRAIRIES WILL LIFT
NORTHEASTWARD INTO THE HUDSON BAY THROUGH TUESDAY, BRINGING
CONTINUED BREEZY SOUTHWEST WINDS TO LAKE MICHIGAN THROUGH
TUESDAY. A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH THIS
EVENING FOR GUSTY SOUTHWEST WINDS FROM PORT WASHINGTON
SOUTHWARD. WITH A WARM, MOIST AIRMASS MOVING NORTHWARD, PATCHY
DENSE FOG IS ALSO EXPECTED OVERNIGHT INTO TUESDAY MORNING. A
FRONT FROM THE CANADIAN LOW WILL SETTLE OVER THE LAKE TONIGHT,
LINGERING THROUGH THE WEEK AND ALLOWING FOR ON- AND-OFF
THUNDERSTORMS THROUGH FRIDAY. MEANWHILE, HIGH PRESSURE AROUND
30.0 INCHES OF THE SOUTHEAST U.S. WILL KEEP WINDS GENERALLY
SOUTHERLY THROUGH WEDNESDAY. THURSDAY, LOW PRESSURE FINALLY
EXITS INTO THE CANADIAN MARITIMES, BRINGING THE FRONT INTO THE
OHIO VALLEY AND ALLOWING WINDS TO SHIFT TO NORTHEASTERLY,
REMAINING NORTHEASTERLY THROUGH FRIDAY.
MH
MKX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
LM...SMALL CRAFT ADVISORY...LMZ644-LMZ645-LMZ646 UNTIL 6 PM MONDAY.
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