304
FXUS63 KMKX 302041
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
341 PM CDT SUN AUG 30 2026
KEY MESSAGES
- BUILDING HEAT AND HUMIDITY THROUGH MIDWEEK. HEAT INDEX VALUES
NEAR 100 DEGREES POSSIBLE ACROSS FAR SOUTHERN WISCONSIN
TUESDAY AND WEDNESDAY.
- RAIN AND SCATTERED STORMS POSSIBLE THROUGH THIS EVENING,
EXITING BY SUNSET. LATE TONIGHT, SCATTERED STORMS REDEVELOP
ACROSS MUCH OF SOUTHERN WISCONSIN, CONTINUING INTO MONDAY
MORNING BEFORE TAPERING OFF.
- STORM CHANCES (~15%) RETURN MONDAY AFTERNOON ALONG A WEAK COLD
FRONT. A FEW OF THESE STORMS MAY BECOME SEVERE, IF THEY
DEVELOP.
- UNCERTAINTY REMAINS IN TIMING AND INTENSITY OF STORMS MONDAY
NIGHT THROUGH THE END OF THE WEEK AS AN ACTIVE PATTERN REMAINS
OVER THE GREAT LAKES REGION.
SHORT TERM
ISSUED 341 PM CDT SUN AUG 30 2026
TONIGHT THROUGH MONDAY NIGHT:
SCATTERED THUNDERSTORMS EARLY THIS AFTERNOON HAVE GENERALLY
MERGED INTO A SINGLE AREA OF WIDESPREAD RAINFALL, WHICH WILL
GRADUALLY PROPAGATE EASTWARD INTO LAKE MICHIGAN BY SUNSET.
OVERNIGHT, STIFF SOUTHWESTERLY WINDS WILL DEVELOP BETWEEN 850
AND 500 MB, ALLOWING FOR MUCAPE ~500 J/KG TO BUILD ACROSS THE
REGION AND SCATTERED STORMS TO DEVELOP AFTER MIDNIGHT INTO THE
MORNING HOURS. THESE STORMS WILL GRADUALLY SLIDE SOUTHEASTWARD
INTO MIDDAY MONDAY AS LOW PRESSURE FINALLY PROPAGATES
SOUTHEASTWARD INTO SOUTHERN MINNESOTA. A WEAK COLD FRONT WITH
THIS SYSTEM WILL SERVE AS THE FOCAL POINT FOR THE NEXT ROUND OF
POTENTIAL STORMS ON MONDAY AFTERNOON, BUT THE INTENSITY OF THIS
ROUND IS DEPENDENT ON HOW LATE IN THE DAY THE MORNING ROUND
LINGERS (I.E., HOW MUCH THE CAPPING INVERSION CAN WHITTLE AWAY
AFTER MORNING PRECIPITATION ENDS). IF STORMS DO DEVELOP IN THE
AFTERNOON HOURS, THEY WOULD BE CAPABLE OF PRODUCING SMALL HAIL
AND GUSTY WINDS WITH INVERTED V SOUNDINGS AND MUCAPE BUILDING
BACK INTO THE 1500 J/KG REALM. 0-6 KM SHEAR 35-40 KT WILL ALLOW
FOR UPDRAFTS TO SUSTAIN THEMSELVES IF THE CAP CAN BE BROKEN. A
MARGINAL RISK (1/5) IS IN EFFECT FOR SOUTHWESTERN TO CENTRAL
WISCONSIN FOR THESE CONCERNS.
OVERNIGHT MONDAY INTO TUESDAY, UNCERTAINTY DEVELOPS WITH TIMING
AND PLACEMENT OF STORMS, AS RIDGING SHIFTS SOUTHWARD AND THE
PARENT LOW LIFTS NORTHWARD. ISOLATED TO SCATTERED STORMS ARE
STILL POSSIBLE, BUT NOT LIKELY AT THIS TIME (15-20% CHANCES).
MH
LONG TERM
ISSUED 341 PM CDT SUN AUG 30 2026
TUESDAY THROUGH SUNDAY:
HEAT AND HUMIDITY BUILDS ACROSS SOUTHERN WISCONSIN TUESDAY, WITH
HEAT INDEX VALUES IN THE MID TO UPPER 90S EXPECTED. HIGHEST
TEMPERATURES ARE EXPECTED NEAR THE WI/IL BORDER, AND A FEW SPOTS
MAY BREAK 100 DEGREE HEAT INDEX VALUES WITH TEMPERATURES IN THE
UPPER 80S. HOWEVER, OVERRUNNING PRECIPITATION FROM THE PREVIOUS
NIGHT, SHOULD IT DEVELOP, COULD TEMPER THESE HIGH TEMPERATURES
AND PREVENT HEAT ADVISORY CRITERIA FROM BEING MET. SOUTHWESTERLY
WINDS WILL ALLOW FOR HEAT TO MAKE IT ALL THE WAY TO LAKE
MICHIGAN, ALTHOUGH AFTERNOON LAKE BREEZE INFLUENCE MAY OFFER
SOME RELIEF. OVERNIGHT TUESDAY, LLJ DYNAMICS RETURN TO THE AREA,
WITH WIDESPREAD PRECIPITATION POSSIBLE IN THE WAA REGION ACROSS
CENTRAL WISCONSIN TO NORTHERN IOWA. IF THIS PRECIPITATION IS
ABLE TO FORM A COLD POOL, SEVERE WEATHER WOULD BECOME POSSIBLE
AS AN MCS MOVES EASTWARD THROUGH THE MEAN FLOW. KEPT NBM POPS OF
20-40%.
ISOLATED STORMS MAY LINGER INTO WEDNESDAY, BUT WITH BUILDING
RIDGING NOT ANTICIPATING SIGNIFICANT IMPACTS. THE MORE IMPACTFUL
STORY AT THIS POINT WILL BE THE HEAT INDEX VALUES IN THE UPPER
90S TO POTENTIALLY 100 DEGREES NEAR THE IL BORDER WHERE AIR
TEMPERATURES REACH 90 DEGREES. CLOUD COVER REMAINING ACROSS
CENTRAL WI WILL KEEP HEAT CONCERNS LOWER, WITH INDICES NEAR 90
DEGREES AND TEMPERATURES IN THE MID-80S. WEDNESDAY NIGHT, LLJ
FOCUSES ON CENTRAL IOWA, WHICH INDICATES A DECAYING MCS MAY
MOVE EASTWARD THROUGH SOUTHERN WISCONSIN INTO THURSDAY MORNING.
GOING THROUGH THE REST OF THE WORKWEEK, CONTINUED PERIODS OF
ON-AND-OFF THUNDERSTORMS ARE EXPECTED AS SOUTHERN WISCONSIN
REMAINS ALONG THE NORTHERN EDGE OF RIDGING ACROSS THE SOUTHEAST
AND MISSISSIPPI VALLEY REGIONS. EXACT DETAILS WILL BE REFINED AS
EVENTS APPROACH.
PATTERN LOOKS TO DRY OUT INTO NEXT WEEKEND AS A DRIER AIRMASS
FROM NORTHEASTERN CANADA WORKS ITS WAY SOUTHWARD INTO THE GREAT
LAKES REGION.
MH
AVIATION
ISSUED 341 PM CDT SUN AUG 30 2026
MVFR TO VFR CONDITIONS CONTINUE THROUGH THIS EVENING, WITH VFR
CONDITIONS EXPECTED AS RAIN AND ISOLATED THUNDERSTORMS TAPER
OFF AFTER SUNSET TONIGHT. GUSTY SOUTHWESTERLY WINDS WILL
DIMINISH AFTER SUNSET AS WELL, WITH LLWS DEVELOPING AS SURFACE
WINDS DIMINISH. DURING THE LATE OVERNIGHT HOURS TONIGHT, EXPECT
WIDELY SCATTERED SHOWERS AND STORMS TO DEVELOP ONCE AGAIN,
ALTHOUGH THE MAJORITY OF THE AREA WILL REMAIN VFR. ISOLATED
STORMS MAY BRING MVFR CEILINGS AND VISIBILITES, BUT CONFIDENCE
IN TIMING AND PLACEMENT IS NOT HIGH. STORMS WILL END MID-
MORNING AND SOUTHWESTERLY WINDS WILL ONCE AGAIN INCREASE TO GUST
AROUND 15-20 KT. DURING THE AFTERNOON TO EVENING HOURS,
ADDITIONAL ISOLATED STORMS ARE POSSIBLE.
MH
MARINE
ISSUED 341 PM CDT SUN AUG 30 2026
BREEZY SOUTHERLY WINDS WILL GRADUALLY DIMINISH TONIGHT AS HIGH
PRESSURE OF 30.1 INCHES MOVES SOUTH INTO THE APPALACHIANS AND LOW
PRESSURE OF 29.7 INCHES LIFTS INTO THE CANADIAN PRAIRIES AND
DEEPENS TO 29.5 INCHES. A SMALL CRAFT ADVISORY REMAINS IN EFFECT
FOR NEARSHORE REGIONS OF SOUTHERN WISCONSIN THROUGH THIS EVENING
FOR CONTINUED GUSTY SOUTHWEST WINDS AND ELEVATED WAVES. SOUTHWESTERLY
WINDS ARE EXPECTED TO CONTINUE THROUGH TUESDAY AS LOW PRESSURE
CONTINUES TO DOMINATE THE PATTERN AND SLOWLY MOVES EAST THROUGH
CANADA. EXPECTING SCATTERED THUNDERSTORMS ON- AND-OFF THROUGH
THE END OF THE WEEK AS A WEAK FRONT LINGERS ACROSS THE REGION.
THE FRONT WILL FINALLY SINK SOUTHWARD WEDNESDAY INTO THURSDAY,
WITH LIGHT NORTHERLY WINDS EVENTUALLY TAKING HOLD.
MH
MKX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
LM...SMALL CRAFT ADVISORY...LMZ643-LMZ644-LMZ645-LMZ646 UNTIL 5 PM
SUNDAY.
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