818
FXUS63 KMKX 301131
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
631 AM CDT WED SEP 30 2026
KEY MESSAGES
- ROUNDS OF MODERATE RAIN WILL SPREAD INTO SOUTHERN WISCONSIN
TONIGHT INTO WEDNESDAY MORNING, WITH ROUNDS OF MODERATE TO
HEAVY RAIN AT TIMES WEDNESDAY NIGHT INTO THURSDAY. A FEW
RUMBLES OF THUNDER MAY OCCUR AS WELL, PARTICULARLY TONIGHT
INTO TOMORROW. THE HEAVIEST RAINFALL SHOULD OCCUR TOWARD THE
ILLINOIS BORDER. RISES IN RIVERS AND PONDING OF WATER IN LOW
LYING AREAS ARE POSSIBLE.
- HIGH SWIM RISK CONDITIONS ARE EXPECTED FOR THE LAKE MICHIGAN
BEACHES IN SHEBOYGAN COUNTY FROM MIDDLE MORNING TO MIDDLE
EVENING WEDNESDAY. STAY OUT OF THE WATER DURING THIS PERIOD
AND AWAY FROM DANGEROUS AREAS LIKE PIERS AND BREAKWALLS.
UPDATE
ISSUED 609 CDT WED SEP 30 2026
STEADY LIGHT TO MODERATE RAIN CONTINUES OVER MUCH OF SOUTHERN
WISCONSIN THIS MORNING. MRMS SHOWS THE HIGHER ACCUMULATIONS HAVE
OCCURRED OVER DODGE AND COLUMBIA COUNTIES SO FAR THIS MORNING,
WITH A WISCONET SITE FROM LOST LAKE OBSERVING 0.33 INCHES. ALSO
WITHIN THE BAND, PRAIRIE DU SAC RECORDED 0.34 INCHES. ANOTHER
0.25 TO 0.5 INCHES OF RAIN ARE PROJECTED TO OCCUR BEFORE A LULL
IN THE PRECIPITATION DEVELOPS AROUND NOON, GIVING WAY TO
SHOWERY LIGHT RAIN ALONG THE WI/IL BORDER, AND SCATTERED DRIZZLE
FURTHER NORTH INTO SOUTHERN WI AWAY FROM THE BORDER.
RAIN RATES THEN PICK UP AGAIN TONIGHT AS THE MAIN SFC TROUGH
AND A WEAK SHORTWAVE MOVE OVERHEAD. WE SHOULD REMAIN RELATIVELY
THUNDERLESS THIS MORNING, BUT BETTER MUCAPE AROUND 250 J/KG
MOVES OVERHEAD TONIGHT AND MAY BE ENOUGH TO SUPPORT INTERMITTENT
EMBEDDED THUNDER.
CMILLER
SHORT TERM
ISSUED 1058 PM CDT TUE SEP 29 2026
TODAY THROUGH THURSDAY NIGHT:
A PASSING TROUGH WITH GOOD PVA, GREAT MID LEVEL WAA AND A LLJ,
ALL THE ITEMS NEEDED FOR A GOOD RAIN HERE IN WISCONSIN. RAIN IS
EXPECTED TO PERSIST THROUGH MUCH OF THE NIGHT AND INTO WEDNESDAY
MORNING. THE LLJ IS SLOWLY TILTING AND MOVING IN FROM THE WEST
AND SO TOO IS THE MID LEVEL MOISTURE. DEWPOINTS HAVE SLOWLY
RISEN ACROSS FAR EASTERN WISCONSIN THIS EVENING AND WILL
CONTINUE TO DO SO AS VIRGA MOVES IN AND WAA CONTINUES. SO WHILE
THERE IS RAIN ON RADAR ITS NOT MAKING IT TO THE GROUND
EVERYWHERE YET, BUT THAT WILL COME WITH TIME. WE WILL BE MISSING
OUR CHEMICAL X (INSTABILITY) DURING THE OVERNIGHT HOURS, SO
THERE WILL BE A DISTINCT LACK OF ANY THUNDER. WITH THE PRESENCE
OF THE LOW LEVEL JET, WE CAN'T COMPLETELY RULE OUT THAT THE
FORCING COULD BE ENOUGH FOR A ERRONEOUS RUMBLE OR TWO.
THANKFULLY THIS WONT MESS WITH OUR PERFECT RECIPE FOR RAIN.
AS THE LLJ CONTINUES TO TILT OVER THE STATE, IT WILL EVENTUALLY
MOVE OUT (TOPPLE OVER), RUNNING ALONG THE WI/IL BORDER. THIS IS
EXPECTED TO HAPPEN DURING THE LATE MORNING AND AFTERNOON HOURS
WEDNESDAY WHICH WILL MOVE THE FORCING OUT OF SOUTHERN WISCONSIN.
THIS SHOULD EFFECTIVELY BRING AN END TO THE RAINFALL FOR
SOUTHERN WISCONSIN AS WE WATCH IT ALL PASS JUST TO THE SOUTH.
THIS IS EXPECTED TO BE TEMPORARY AS THE RAIN WILL RETURN IN THE
EVENING AS THE FORCING AND LIFT RETURN AHEAD OF THE NEXT ROUND
OF RAIN WEDNESDAY NIGHT INTO THURSDAY. FOR MANY IT MAY FEEL AS
IF THE DAY IS SAVED... FROM MORE RAIN, BUT REST ASSURED IT WILL
RETURN.
FOR MUCH OF THURSDAY, MODERATE TO HEAVY RAIN IS EXPECTED. WHILE
THIS WONT BE MUCH OF CHANGE FROM WEDNESDAY WITH PWAT VALUES WHAT
THEY ARE (1.5 TO 2). WHAT WILL BE DIFFERENT IS THE MID LEVEL
TROUGH AXIS IS EXPECTED TO BE ACROSS SOUTHERN WISCONSIN AND
NORTHERN ILLINOIS AND THERE WILL BE ADDED FRONTOGENESIS TO HELP
FUEL THE RAIN MACHINE. SOUNDINGS SUPPORT THIS WELL WITH SOME
NICE MOIST ADIABATIC PROFILES. WITH A LOT MORE FORCING IN PLAY
HERE, THERE IS A BETTER CHANCE FOR SOME THUNDERSTORMS. BETTER
BUT NOT GUARANTEED, SO WILL HAVE TO WAIT FOR THE CALL. RAIN AND
ANY ISOLATED STORMS ARE EXPECTED TO COME TO AN END THURSDAY
NIGHT AS THE COLD FRONT MOVES THROUGH THE AREA. DRIER AIR WILL
MOVE INTO THE STATE BEHIND THE COLD FRONT.
THE SAME CAN BE SAID FOR ANY FLOODING CONCERNS. THERE IS STILL
A FAIR AMOUNT OF SPREAD AMONG GUIDANCE ON WHERE EXACTLY THE
HEAVIEST RAINFALL WILL LIE. GENERALLY SPEAKING WERE LOOKING FROM
AN AREA ALONG OR SOUTH OF INTERSTATE 94 INTO NORTHERN ILLINOIS
FOR THE AXIS OF HIGHEST RAINFALL. GENERALLY SPEAKING RAINFALL
NORTH OF I-94 IS EXPECTED TO BE LESS THAN INCH WITH AREAS ALONG
AND SOUTH OF I-94 AROUND 1-3 INCHES. IF THAT AXIS OF HIGHER
RAINFALL REMAINS IN SOUTHERN WISCONSIN ITS NOT OUT OF THE
QUESTION TO SEE LOCALLY HIGHER AMOUNTS UP TO 4 INCHES. AS THINGS
STAND NOW, THE BEST/HIGHEST CHANCES FOR TOTALS UP TO 4 INCHES
ARE EXPECTED ALONG THE WI/IL BORDER. NOW A SAVING GRACE IN ALL
OF THIS IS THAT THESE ARE RAINFALL TOTALS FROM TONIGHT THROUGH
THURSDAY NIGHT, SO THIS ISNT COMING ALL AT ONCE. CAN'T RULE OUT
SOME URBAN IMPACTS WITH ANY HEAVIER RAIN, OF WHICH WE ARE
EXPECTING. ANYTHING LARGER THAN THAT WE WILL HAVE TO KEEP AN EYE
ON TRAINING AND RAINFALL RATES.
OTHERWISE THE ONLY OTHER NOTE WORTH ITEM IN THE SHORT TERM IS
THE HIGH SWIM RISK ACROSS SHEBOYGAN COUNTY FOR WEDNESDAY.
ONSHORE WINDS AND BUILDING WAVES WILL POSE A RISK TO ANYONE ON
THE BEACH AND THE SUBSEQUENT SMALL CRAFT ADVISORY WILL POSE A
RISK TO THOSE IN THE NEARSHORE WATERS. STAY OUT OF THE WATER AND
AWAY FROM DANGEROUS AREAS (PIERS AND BREAKWALLS).
PATTERSON
LONG TERM
ISSUED 1058 PM CDT TUE SEP 29 2026
FRIDAY THROUGH MONDAY:
AS THE COLD FRONT EXITS TO THE SOUTHEAST LATE THURSDAY, DRIER
AIR AND HIGH PRESSURE IS EXPECTED TO MOVE INTO WISCONSIN. THIS
WILL BRING A PERIOD OF DRY AND COOL WEATHER ACROSS THE AREA
THROUGH SATURDAY. HIGH TEMPERATURES ARE EXPECTED TO BE IN THE
LOW TO MID 60S WITH OVERNIGHT LOWS IN THE LOWER TO UPPER 40S.
FRIDAY NIGHT WILL HAVE THE BEST POTENTIAL FOR A CHANCE AT SEE
SOME UPPER 30 DEGREE TEMPERATURES OVERNIGHT.
LATE SATURDAY INTO SUNDAY GUIDANCE AS A LOW PRESSURE SYSTEM
PASSING JUST TO THE NORTH OF THE FORECAST AREA. THE BETTER LIFT
AND FORCING LOOK TO REMAIN ACROSS NORTHERN WISCONSIN AND CANADA.
MOISTURE RETURN LOOKS TO BE VERY WEAK TOO WHICH WILL FURTHER
LIMIT THE POTENTIAL FOR ANY RAIN. WHILE VERY LOW, OPTED TO KEEP
THE 10-15% CHANCE FOR RAIN ACROSS CENTRAL WISCONSIN AS A FEW
MEMBERS OF GUIDANCE DO HAVE THE SFC LOW A BIT FURTHER SOUTH.
THEN HIGH PRESSURE RETURNS KEEPING THINGS COLD AND DRY THROUGH
THE REST OF THE EXTENDED.
PATTERSON
AVIATION
ISSUED 627 AM CDT WED SEP 30 2026
RAIN CONTINUES THIS MORNING WITH A MIX OF FLIGHT CATEGORIES,
RANGING FROM IFR TO VFR. BY 18Z TODAY, IFR CEILINGS SHOULD TAKE
HOLD AREA-WIDE AND STEADY RAIN SHOULD END, GIVING WAY TO -DZ
AND SHOWERY LIGHT RAIN ALONG THE WI/IL BORDER. STEADIER RAIN
WILL MOVE IN TONIGHT, WITH CEILINGS REMAINING IN THE IFR
CATEGORY. WINDS REMAIN SOUTHERLY TO SOUTHWESTERLY TODAY WITH
GUSTS TO 20 KNOTS.
CMILLER
MARINE
ISSUED 1058 PM CDT TUE SEP 29 2026
SOUTHERLY WINDS WILL INCREASE TONIGHT INTO WEDNESDAY AND THEN
BECOME SOUTHWESTERLY WEDNESDAY NIGHT INTO THURSDAY. GUSTS TO 30
KNOTS WILL BE POSSIBLE OVER THE OPEN WATERS, PARTICULARLY THE
CENTRAL AND NORTHERN PORTION OF THE LAKE. A COLD FRONT WILL PASS
SOUTHEAST DOWN THE LAKE THURSDAY TURNING WINDS TO TO THE NORTH
TO NORTHEAST. A SMALL CRAFT ADVISORY IS IN EFFECT WEDNESDAY
MORNING THROUGH WEDNESDAY EVENING FOR THE BREEZY WINDS AND
BUILDING WAVES.
STRONG HIGH PRESSURE AROUND 30.4 INCHES WILL OVERSPREAD
THE GREAT LAKES FRIDAY NIGHT. A FAST-MOVING LOW PRESSURE SYSTEM
AROUND 29.8 INCHES SHOULD MOVE ACROSS OR NORTH OF LAKE SUPERIOR
SATURDAY NIGHT, WITH HIGH PRESSURE AROUND 30.4 INCHES MOVING
SOUTHEAST INTO THE REGION BY EARLY NEXT WEEK. NORTHWEST TO NORTH
WINDS SHOULD RESULT ACROSS LAKE MICHIGAN. WAVES MAY REACH SMALL
CRAFT ADVISORY LEVELS FRIDAY INTO SATURDAY.
PATTERSON
MKX WATCHES/WARNINGS/ADVISORIES
WI...BEACH HAZARDS STATEMENT...WIZ052...10 AM WEDNESDAY TO 10 PM
WEDNESDAY.
LM...SMALL CRAFT ADVISORY...LMZ643...10 AM WEDNESDAY TO 10 PM
WEDNESDAY.
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