882
FXUS63 KMKX 230848
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
348 AM CDT WED JUL 23 2025
KEY MESSAGES
- HIGH SWIM RISK DUE TO BUILDING WAVES AND DANGEROUS CURRENTS
FOR SHEBOYGAN COUNTY TODAY FROM NOON THROUGH THE EVENING
HOURS. MODERATE SWIM RISK FOR OZAUKEE COUNTY IS EXPECTED.
- SCATTERED SHOWERS AND STORMS THIS MORNING, MOST LIKELY WEST OF
A LINE FROM JANESVILLE TO FOND DU LAC.
- DANGEROUS HEAT WILL PUSH INTO SOUTHERN WISCONSIN THIS
AFTERNOON AND MAY LINGER OVER SOUTHEAST WI THROUGH THURSDAY.
HEAT INDICES OF 100 TO 105 DEGREES ARE EXPECTED. A HEAT
ADVISORY IS IN EFFECT FOR WEDNESDAY WITH ANOTHER MAY BE
NEEDED THURSDAY.
- INCREASED SHOWER AND THUNDERSTORM CHANCES (>60%) FOR THURSDAY
WITH PERIODIC CHANCES FRIDAY AND SATURDAY.
SHORT TERM
ISSUED 348 AM CDT WED JUL 23 2025
TODAY THROUGH THURSDAY:
A MESOSCALE CONVECTIVE VORTEX (MCV) IS TRACKING INTO SOUTHWEST
WI EARLY THIS MORNING. MANY MODELS ARE HANDLING THIS WELL,
ALTHOUGH THERE IS UNCERTAINTY ABOUT HOW WELL IT WILL SUSTAIN
ITSELF INTO EASTERN WI. AREAS WEST OF A LINE FROM JANESVILLE TO
FOND DU LAC HAVE THE BEST CHANCE OF THE SCATTERED STORMS, WITH
LOWER CHANCES EAST. THE ENVIRONMENT HAS ML CAPE OF 1000 J/KG BUT
WEAK SHEAR. THE 0-1KM LOW LEVEL HELICITY IS DECENT, WHICH IS
CHARACTERISTIC OF AN MCV. RIGHT NOW, THE SURFACE INVERSION IS
KEEPING US STABLE. IF ANY STRONGER STORMS DEVELOP, A FEW GUSTS
UP TO 40KT ARE POSSIBLE. WITH PRECIPITABLE WATER VALUES OF
AROUND 2 INCHES, VERY HEAVY DOWNPOURS ARE EXPECTED. THE SYSTEM
IS MOVING SLOWLY, SO IF THERE ARE TRAINING STORMS, THEN BRIEF
URBAN FLOODING IS POSSIBLE. THE MCV COMPLEX SHOULD EXIT FOND DU
LAC COUNTY BY 11 AM.
HEAT AND HUMIDITY WILL QUICKLY BUILD INTO SOUTHERN WI THIS
AFTERNOON ON BREEZY SOUTH-SOUTHWEST WINDS. WITH THE CLOUDS
CONFINED TO THE AREA OF CONVECTION THIS MORNING, SKIES OVER
SOUTHERN WI SHOULD BE CLEAR THIS AFTERNOON. THIS WILL ALLOW
TEMPS TO REACH THE LOWER 90S. WITH DEWPOINTS IN THE MID 70S
ADVECTING IN, THE HEAT INDEX VALUES WILL BE IN THE 100 TO 105
RANGE, WITH A FEW POCKETS OF HIGHER VALUES UP TO 107 DEVELOPING.
NO CHANGE TO THE CURRENT HEAT ADVISORY, BUT WE STILL CAN'T RULE
OUT THE POTENTIAL TO UPGRADE A SMALLER AREA (PROBABLY SOUTHEAST
WI) INTO A WARNING- JUST NOT ENOUGH CONFIDENCE.
WARM TEMPERATURES WILL CONTINUE TONIGHT WITH LOWS ONLY DROPPING
TO THE MID 70S (UPPER 70S IN THE EAST). THURSDAY HIGHS WILL BE
DEPENDENT UPON SKY COVER. RIGHT NOW, THE BETTER CHANCE OF HIGHS
IN THE 90S IS IN FAR SOUTHEAST WI. PEAK HEAT INDEX VALUES ARE
FORECAST AROUND 100 TO 102 THERE. THERE IS TOO MUCH UNCERTAINTY
IN EXACTLY WHERE ANY THUNDERSTORM COMPLEXES WILL BE (AND CLOUDS
THAT COULD KEEP TEMPS LOWER), SO OPTED NOT TO EXTEND OUR
CURRENT ADVISORY INTO THE NEXT DAY.
OUR FORECAST HAS A LOW CHANCE (20-30%) FOR STORMS IN SOUTH
CENTRAL WI DURING THE MORNING, AND A MUCH HIGHER CHANCE (65-75%)
IN THE AFTERNOON FOR MOST OF SOUTHERN WI. THE HIGHER CHANCE
(55-65%) LINGERS OVER SOUTHEAST WI DURING THE EVENING AND TAPERS
OFF NORTH TO SOUTH OVERNIGHT. THE FORECAST CAPTURES THE REGION
OF A FRONTAL BOUNDARY THAT WILL SLOWLY SAG THROUGH THE AREA.
HOWEVER, THE MESO MODEL FORECAST REFLECTIVITIES PAINT A
DIFFERENT PICTURE. THIS IS A RESULT OF HIGH UNCERTAINTY ABOUT
WHERE OUTFLOW BOUNDARIES AND MCVS WILL EXIST AFTER THIS
AFTERNOON. ONE IDEA IS THAT AN OUTFLOW BOUNDARY WOULD MAKE IT
INTO SOUTH CENTRAL WI (AFTER ANY SHOWERS/STORMS DISSIPATED)
EARLY THURSDAY MORNING. THIS WOULD ACT AS A FOCAL POINT FOR
THUNDERSTORMS TO DEVELOP IF THERE ARE ANY REMNANT MCVS THAT
CROSS OVER DURING THE MORNING HOURS. THE OTHER IDEA IS THAT A
LINE OF THUNDERSTORMS WOULD DEVELOP ALONG THAT STALLED BOUNDARY
MID MORNING AND LIMP ALONG INTO SOUTHEAST WI DURING LATE
MORNING/MIDDAY BECAUSE THEY ARE NOT TIED TO ANY MAJOR SYNOPTIC
FORCING. ONE OTHER IDEA IS THAT STORMS WOULD DEVELOP ALONG THE
ACTUAL SURFACE FRONT AS IT TRACKS THROUGH SOUTHERN WI DURING THE
LATE AFTERNOON.
CRONCE
LONG TERM
ISSUED 348 AM CDT WED JUL 23 2025
FRIDAY THROUGH TUESDAY:
COLD FRONT WILL BE MOST OF THE WAY THROUGH THE AREA BY FRIDAY,
WITH CONVECTION REMAINING POSSIBLE AS THE FRONT STALLS OUT EITHER
ALONG OR JUST SOUTH OF THE ILLINOIS/WISCONSIN BORDER. HIGH
PRESSURE WILL PROPAGATE JUST NORTH OF WISCONSIN ON FRIDAY,
BRINGING CONVERGENT FLOW ALONG AND NORTH OF THE FRONT AND
POTENTIALLY DEVELOPING ADDITIONAL STORMS(20-50% CHANCE, WITH THE
BEST POTENTIAL SOUTHWARD). HOWEVER, PLENTY OF DRY AIR WORKING IN
ALOFT AND BULK SHEAR VECTORS ONLY AROUND 20 KT WILL LEAD TO MORE
POP-UP ACTIVITY RATHER THAN STRONGER STORM CLUSTERS. BEST CHANCES
FOR STORMS ARE NEAR THE WISCONSIN/ILLINOIS BORDER, AS WELL AS IN
SOUTHWESTERN WISCONSIN WHERE THE EDGES OF THE HIGH PRESSURE WILL
SITUATE.
SATURDAY, HIGH PRESSURE WILL PROPAGATE EASTWARD INTO SOUTHEASTERN
ONTARIO AND THE NORTHEAST U.S., WHILE A STRONG SHORTWAVE
PROGRESSES INTO THE HUDSON BAY IN CANADA. IN ADDITION, THE
REMNANTS OF A COLORADO LOW WILL PROPAGATE ALONG THE STATIONARY
FRONT NORTHEASTWARD INTO NORTHERN ILLINOIS AND POTENTIALLY AS FAR
NORTH AS SOUTHERN WISCONSIN, BRINGING ADDITIONAL THUNDERSTORM AND
RAINFALL POTENTIAL THROUGH THE DAY (~20-40% CHANCE).
250 MB RIDGING REGAINS DOMINANCE ACROSS THE SOUTHEAST U.S. TO THE
SOUTHERN PLAINS GOING INTO SUNDAY, BRINGING A RETURN TO
SOUTHWESTERLY FLOW IN THE MID TO UPPER LEVELS AND THEREFORE A
RETURN TO HEAT GOING INTO THE BEGINNING OF NEXT WEEK. EXPECTING
RIDGING TO REMAIN DOMINANT THROUGH MONDAY, WITH A SHIFT BACK TO
NORTHWESTERLY FLOW INTO TUESDAY AS A STRONG SHORTWAVE ONCE AGAIN
TRAVERSES CANADA AND BRINGS A COLD FRONT THROUGH THE REGION MONDAY
NIGHT INTO TUESDAY. STORMS ARE ALSO POSSIBLE ACROSS THE REGION
DURING THE COLD FRONTAL PASSAGE, WITH TIMING DISCREPANCIES BETWEEN
MODELS AND MODEL RUNS LEADING TO LOWER POPS IN THE NBM.
MH
AVIATION
ISSUED 348 AM CDT WED JUL 23 2025
AN AREA OF THUNDERSTORMS IS SPREADING INTO SOUTH CENTRAL WI
EARLY THIS MORNING. AREAS WEST OF A LINE FROM JANESVILLE TO
FOND DU LAC HAVE THE BEST CHANCE OF THE SCATTERED STORMS, WITH
LOWER CHANCES EAST. A FEW GUSTS UP TO 40KT ARE POSSIBLE WITH
ANY STRONGER STORMS, AS WELL AS LIGHTNING AND HEAVY RAIN.
POCKETS OF MVFR CEILINGS AROUND 2700 FT ARE PRESENT OVER SOUTH
CENTRAL WI EARLY THIS MORNING. AS THE THUNDERSTORM COMPLEX
ROLLS THROUGH, EXPECT PERIODS OF MVFR AND BRIEF IFR. ADDITIONAL
SHOWERS WITH A FEW RUMBLES OF THUNDER AND MVFR CEILINGS ARE
POSSIBLE IN SOUTHEAST WI THIS AFTERNOON.
SKIES WILL CLEAR THIS AFTERNOON, AND GUSTY SOUTH-SOUTHWEST WINDS
ARE EXPECTED ALONG WITH VERY WARM TEMPS AND HIGH HUMIDITY.
CRONCE
MARINE
ISSUED 348 AM CDT WED JUL 23 2025
LOW PRESSURE WILL PUSH INTO THE SOUTHERN MINNESOTA THIS MORNING
AND NORTHERN WISCONSIN BY THIS EVENING. BREEZY SOUTHERLY WIND
GUSTS OF 25 TO 30 KT ARE EXPECTED ACROSS THE NORTHERN TWO-
THIRDS OF THE LAKE, PRIMARILY DURING THE AFTERNOON. A SMALL
CRAFT ADVISORY IS IN EFFECT NORTH OF PORT WASHINGTON DURING THE
AFTERNOON.
THERE ARE CHANCES FOR STORMS BEGINNING LATE MORNING AND
CONTINUING THROUGH FRIDAY ALONG A FRONTAL BOUNDARY. INITIALLY,
TODAY INTO THURSDAY MORNING, EXPECT THE FRONT TO REMAIN
STATIONARY ACROSS THE NORTHERN HALF OF THE LAKE. THURSDAY
AFTERNOON THROUGH FRIDAY, EXPECT THE FRONT TO PUSH SOUTHWARD,
BRINGING STORMS SOUTHEASTWARD THROUGH THE REMAINDER OF THE OPEN
WATERS. A LOW PRESSURE TROUGH AROUND 29.8 INCHES WILL DROP
THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY, SHIFTING WINDS TO
WESTERLY.
CRONCE
MKX WATCHES/WARNINGS/ADVISORIES
WI...HEAT ADVISORY...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-
WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-
WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...11 AM
WEDNESDAY TO 8 PM WEDNESDAY.
BEACH HAZARDS STATEMENT...WIZ052...NOON WEDNESDAY TO 10 PM
WEDNESDAY.
LM...SMALL CRAFT ADVISORY...LMZ643...NOON WEDNESDAY TO 10 PM
WEDNESDAY.
VISIT US AT WEATHER.GOV/MILWAUKEE
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSMILWAUKEE
WWW.TWITTER.COM/NWSMILWAUKEE
WWW.YOUTUBE.COM/NWSMILWAUKEE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page