845
FXUS63 KMKX 250400
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1100 PM CDT THU SEP 24 2026
KEY MESSAGES
- SLIGHTLY BELOW NORMAL TEMPS CONTINUE FOR THE NEXT SEVERAL
DAYS.
- PATCHY DENSE FOG IN SOUTHWESTERN WISCONSIN IS POSSIBLE EARLY
FRIDAY MORNING.
- NEXT CHANCES FOR RAIN AND STORMS RETURN TUESDAY INTO
WEDNESDAY.
SHORT TERM
ISSUED 1050 PM CDT THU SEP 24 2026
FRIDAY THROUGH MONDAY:
SOME WEAK MID-LEVEL WAA AND CYCLONIC FLOW ALOFT NORTH OF THE
CREST OF THE 500MB RIDGE HAS FORMED SOME AREAS OF LIGHT RAIN
OVER WEST CENTRAL WI, SOUTHEASTERN MN, AND MUCH OF IA, WHICH
WILL SLOWLY DRIFT EASTWARD INTO SOUTHERN WI AND ERODE (DUE TO
LOW-LEVEL DRY AIR) WITH TIME. AS SUCH, WE COULD SEE SOME OFF
AND ON LIGHT RAIN (10-30% CHANCES / COVERAGE) ACROSS THE AREA
FROM PREDAWN THROUGH AROUND 8 AM THIS MORNING, WITH THE HIGHEST
CONFIDENCE WEST OF MADISON.
HIGH PRESSURE REMAINS DOMINANT OVER SOUTHERN ONTARIO CANADA AND
THE GREAT LAKES THROUGH THE REST OF THE WEEKEND AND INTO EARLY
NEXT WEEK, SLOWLY WEAKENING WITH TIME. COOL, QUIET, AND
PREDOMINANTLY DRY WEATHER IS EXPECTED THROUGH THE PERIOD, WITH
HIGHS IN THE MID TO UPPER 60S THIS WEEKEND AND ROUGHLY 70
DEGREES ON MONDAY. A LIGHT EAST OR SOUTHEAST BREEZE ACROSS THE
REGION AT TIMES (GENERALLY 10 MPH OR LESS), OTHERWISE
PRACTICALLY CALM. OUR BEST SHOT AT A STRAY RAIN SHOWER THIS
WEEKEND WOULD BE SATURDAY NIGHT INTO SUNDAY MORNING (10-20%
CHANCE) MAINLY WEST OF A JANESVILLE TO GREEN LAKE LINE AS AN
ADDITIONAL ROUND OF MID-LEVEL WAA ATTEMPTS TO PUSH EAST INTO
SOUTHERN WI, FIGHTING LOW-LEVEL DRY AIR ONCE AGAIN.
SHEPPARD
LONG TERM
ISSUED 1050 PM CDT THU SEP 24 2026
MONDAY NIGHT THROUGH THURSDAY:
ECMWF AND GFS ENSEMBLE OUTPUT APPEARS MUCH LEST ORGANIZED FOR
THE TROUGH AND LOW PRESSURE SYSTEM WE WERE EXPECTING MIDWEEK
NEXT WEEK, YIELDING SOME SERIOUS CONCERNS FOR PREDICTABILITY,
BUT THE GENERAL CONSENSUS REMAINS THE SAME FOR THIS FORECAST
PERIOD: THE RIDGE OVER THE PLAINS FINALLY BREAKS DOWN, AND A
TROUGH OR OPEN WAVE (OF UNKNOWN AMPLITUDE) IN THE JET KICK
STARTS A MORE ACTIVE / OCCASIONALLY RAINY WEATHER PATTERN FOR
MIDWEEK AND BEYOND ACROSS THE MIDWEST.
FOR MONDAY NIGHT INTO TUESDAY, MODELS HAVE FAIRLY GOOD AGREEMENT
ON A POSITIVELY-TILTED TROUGH DIGGING EAST FROM NEVADA INTO NEW
MEXICO, INDUCING BROAD LOW-PRESSURE OVER THE GREAT PLAINS,
WORKING WITH HIGH PRESSURE OVER THE OHIO VALLEY TO DRIVE
INCREASING SOUTHERLY WINDS. WAA DRIVEN RAIN CHANCES BUILD WEST
TO EAST INTO THE CWA THROUGH THE DAY TUESDAY, WITH RAIN LOOKING
LIKELY (60-70% CHANCES) ACROSS THE REGION TUESDAY NIGHT.
WEDNESDAY AND ONWARDS IS WHERE PREDICTABILITY FALLS OFF SHARPLY.
THE 18Z GFS ALLOWS THE AFOREMENTIONED TROUGH TO PRODUCE A
HEALTHY SURFACE LOW AND TRACK IT STRAIGHT TOWARDS THE REGION,
YIELDING SHOWER AND PERHAPS EVEN THUNDERSTORM CHANCES MID TO
LATE WEEK. THE ECMWF MODEL PARTIALLY CLOSES OFF THE NEW MEXICO
TROUGH INTO AN UPPER LOW AND STALLS IT THERE, PREVENTING OR
SUBSTANTIALLY DELAYING MOISTURE RETURN FOR THE MIDWEST (AND
YIELDING LULLS IN THE ACTIVITY MID TO LATE WEEK). UNTIL THINGS
BECOME CLEARER, OUR FORECAST WILL REFLECT BROAD-BRUSHED 30-50%
RAIN CHANCES ACROSS SOUTHERN WI MID TO LATE WEEK.
SHEPPARD
AVIATION
ISSUED 1030 PM CDT THU SEP 24 2026
ISOLATED TO SCATTERED LIGHT RAIN SHOWERS (10-35% COVERAGE)
EXPECTED PREDAWN THROUGH AROUND 8 AM FRIDAY MORNING, WITH THE
HIGHEST CONFIDENCE SOUTH AND WEST OF MSN. CONFIDENCE IS HIGH
ENOUGH FOR PROB30 GROUPS IN THE MSN AND JVL TAFS FOR NOW,
EXCLUDED IT FROM TAFS FURTHER EAST DUE TO LOWER CONFIDENCE. THE
DRY AIR OUGHT TO ERODE MOST OF THE SHOWER ACTIVITY BEFORE IT
TRAVELS EAST TO THE SHORELINE. CLOUDS WITH THIS ACTIVITY SHOULD
GENERALLY BE BETWEEN 3,000 AND 5,000 FT, THOUGH SOME LOCALLY
LOWER PATCHES (MVFR) ARE POSSIBLE DURING AND AFTER THE SHOWERS,
ESPECIALLY EARLY FRIDAY MORNING THROUGH THE MIDDAY HOURS.
TERMINALS WELL WEST OF MADISON COULD SEE SOME FOG DEVELOPING
LATE TONIGHT INTO FRIDAY MORNING IN RESPONSE TO THE LIGHT RAIN
IF APPLICABLE. SOME POCKETS OF FOG AT WEST BEND AND SBM ARE
POSSIBLE AS WELL IN RESPONSE TO SOME GAPS IN THE CLOUDS /
FALLING TEMPERATURES.
FOR THE REST OF FRIDAY AND FRIDAY NIGHT, A LIGHT ESE BREEZE WITH
DIURNAL CUMULUS CLOUDS BETWEEN 3,000 AND 5,000 FT. DRY WEATHER
AND PREDOMINANTLY VFR CEILINGS EXPECTED. CUMULUS CLOUD CEILINGS
SHOULD SCATTER OUT LATER FRIDAY AFTERNOON INTO FRIDAY EVENING,
INCREASING CONFIDENCE IN VFR.
SHEPPARD
MARINE
ISSUED 1030 PM CDT THU SEP 24 2026
OPEN WATERS / SYNOPSIS:
HIGH PRESSURE AROUND 30.4 INCHES WILL LINGER OVER SOUTHERN
ONTARIO CANADA AND THE GREAT LAKES THROUGH FRIDAY AND INTO THE
WEEKEND, GRADUALLY WEAKENING TO 30.1 INCHES. LIGHT EAST TO
SOUTHEAST WINDS EXPECTED AT TIMES, OTHERWISE LIGHT AND VARIABLE.
PREDOMINANTLY DRY AND QUIET WEATHER EXPECTED.
HIGH PRESSURE WILL PROGRESS INTO THE OHIO VALLEY EARLY TUESDAY,
ALLOWING WINDS TO TURN SOUTH AND INCREASE AS LOW PRESSURE DEVELOPS
IN THE CENTRAL PLAINS.
NEARSHORE ZONES:
PLEASANT CONDITIONS EXPECTED THIS WEEKEND INTO EARLY NEXT WEEK.
LIGHT ONSHORE FLOW MAY LIFT WAVES UP TO 2.5 FT AT TIMES, BUT
THAT'S ALL. SMALL CRAFT ADVISORY CONDITIONS MAY RETURN TUESDAY
THROUGH MIDWEEK NEXT WEEK AS BREEZY SOUTHERLY WINDS AND BUILDING
WAVES ARRIVE.
SHEPPARD
MKX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
LM...NONE.
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