076
FXUS63 KGRB 152025
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
325 PM CDT SUN JUN 15 2025
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
KEY MESSAGES
- ISOLATED SHOWERS AND SPRINKLES ARE POSSIBLE OVERNIGHT,
ESPECIALLY WEST AND NORTH OF THE FOX VALLEY/LAKESHORE AREAS.
- A WARM, HUMID, AND STORMY PERIOD IS EXPECTED THROUGH MIDDAY,
AND AGAIN TOWARD FRIDAY/SATURDAY. STRONG TO SEVERE STORMS AND
HEAVY RAINFALL WILL BE POSSIBLE AT TIMES.
DISCUSSION
ISSUED AT 323 PM CDT SUN JUN 15 2025
SHORT TERM...TONIGHT AND MONDAY
WEAK MID-LEVEL CONVERGENCE AND ISENTROPIC ASCENT MAY SPUR ON A FEW
LIGHT SHOWERS ACROSS CENTRAL WI THIS AFTERNOON, HOWEVER, THE BETTER
FORCING REMAINS SOUTHWEST OF THE REGION. OTHERWISE DRY AND MOSTLY
CLOUDY CONDITION WILL CONTINUE THROUGH THIS EVENING ACROSS THE
REGION. SCATTERED SHOWERS MAY DEVELOP ACROSS PORTIONS OF CENTRAL AND
NORTH-CENTRAL WI OVERNIGHT AS SURFACE WINDS VEER AROUND TO THE SOUTH
AND WAA INCREASES.
MONDAY WILL FEEL MUCH MORE LIKE SUMMER AS SOUTH SOUTHWEST WINDS IN
ADVANCE OF A DEVELOPING CYCLONE OVER THE NORTHERN PLAINS FEED MUCH
WARMER AND MORE HUMID AIR INTO WISCONSIN. HIGHS ARE FORECAST TO
REACH THE UPPER 70S TO MIDDLE 80S WITH DEW POINTS IN THE MIDDLE TO
UPPER 60S. THE INCREASING WARMTH AND MOISTURE ALONG WITH WEAK LIFT
MAY INITIATE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS LATE
MONDAY MORNING AND AFTERNOON, HOWEVER, WITH WEAK VERTICAL SHEAR AND
CAPPING IN PLACE DON'T ANTICIPATE ANY OF THESE INITIAL STORMS
BECOMING SEVERE. THE WINDOW FOR SEVERE IS BETWEEN ABOUT 4PM AND
10PM. WILL NEED TO MONITOR UPSTREAM TRENDS MONDAY TO GET A BETTER
HANDLE OF WHEN/IF ANY STRONGER STORMS WILL REACH THE FORECAST AREA.
THE RISK FOR SEVERE THUNDERSTORMS DOES INCREASE DURING THE LATE
AFTERNOON AND EVENING AS CAMS SHOW AN MCS DEVELOPING OVER MINNESOTA
AND PUSHING EAST TOWARD CENTRAL AND NORTHERN WI. THE FINER DETAILS
WITH THIS SYSTEM REMAIN RATHER DIFFICULT TO PIN DOWN AS CAMS STILL
SHOW DIFFERENCES IN THE TIMING AND LOCATION OF THE MIDDLE-LEVEL
SHORTWAVE AND SURFACE COLD FRONT THAT WILL BE THE PRIMARY FORCING
FOR ANY STRONGER STORMS. SHOULD AN MCS MAKE IT TO CENTRAL/NORTHERN
CAMS DO SHOW A RESERVOIR OF 1000-1500 J/KG SBCAPE AND SLIGHTLY
ELONGATED HODOGRAPHS WHICH SUPPORT A MARGINALLY SEVERE HAIL RISK. ANY
BOWING SEGMENTS MAY ALSO POSE A SEVERE WIND RISK.
THE PROGRESSIVE NATURE OF THESE STORMS SHOULD MITIGATE THE FLASH
FLOOD RISK TO A LARGE DEGREE OUTSIDE OF ANY URBAN OR LOW-LAYING
AREAS., HOWEVER, PERIODS OF HEAVY RAIN WILL BE POSSIBLE. PWATS ARE
FORECAST TO BE NEAR 1.5" WHICH IS AROUND THE 90TH PERCENTILE FOR
THIS TIME OF YEAR. SOUNDINGS ALSO SHOW A WARM CLOUD LAYER OF AROUND
8KFT WHICH SHOULD YIELD EFFECT WARM RAIN PROCESSES.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY
THERE IS HIGH CONFIDENCE IN AN ACTIVE WEATHER SETUP ACROSS THE
UPPER MIDWEST/WESTERN GREAT LAKES THROUGH THE LONG TERM FORECAST,
BUT SPECIFIC DETAILS ON EXACTLY WHERE RAIN/THUNDERSTORMS WILL
DEVELOP AND TRACK EACH DAY IS DIFFICULT TO PIN DOWN UNTIL EACH DAY
GETS CLOSER.
THE CURRENT GUIDANCE SUGGESTED A CONVECTIVE SYSTEM WILL DEVELOP
WEST OF THE FORECAST AREA MONDAY AFTERNOON, REACHING NORTH-CENTRAL
WI AROUND OR A LITTLE AFTER 00Z/TUE. THIS SYSTEM WILL INITIALLY
ENTER AN UNSTABLE ENVIRONMENT WITH MUCAPES OF 1000-1500 J/KG,
SUGGESTING SOME STRONG OR SEVERE STORMS MAY CONTINUE (HENCE THE
MARGINAL RISK, LEVEL 1/5 FROM THE SPC) INTO THE EVENING. HOWEVER,
AS INSTABILITY WANES, THE SEVERITY OF ANY STORMS IS LIKELY TO
DECREASE, BUT EXACTLY WHERE AND WHEN THAT OCCURS IS STILL
UNCERTAIN. CURRENT MODELS WOULD SUGGEST WEST OF THE FOX VALLEY.
THERE WILL LIKELY BE A LULL FOR THE REST OF TUESDAY, WITH ANOTHER
COMPLEX DEVELOPING TUESDAY AFTERNOON/EVENING, BUT THIS ONE IS MORE
LIKELY TO REMAIN SOUTH OF THE AREA CLOSER TO WHERE THE SURFACE
FRONT WILL RESIDE, KEEPING THE HEAVIEST OF THE PRECIPITATION
FARTHER SOUTH. THERE REMAINS HIGH UNCERTAINTY WEDNESDAY INTO
THURSDAY WITH AN OVERALL MESSY WEATHER SETUP DUE TO VARIOUS
EMBEDDED SHORTWAVES AND SURFACE FRONTS. THE DEVELOPMENT OF STORMS
OF A STORM COMPLEX EACH DAY WILL DEPEND ON WHAT BOUNDARIES AND
DEBRIS IS LEFTOVER FROM THE DAY BEFORE, AND HOW THIS INTERACTS
WITH ANY UPPER LEVEL FEATURES. RAIN AND THUNDERSTORMS ARE
THROUGHOUT MOST FORECAST BLOCKS, BUT IT WILL NOT BE RAINING OR
STORMING CONTINUOUSLY. AND THERE IS POTENTIAL BOTH DAYS END UP
MOSTLY DRY.
UPPER FLOW AMPLIFIES NEAR THE END OF THE WEEK, BRINGING NORTHEAST
WI UNDER THE RRQ OF AN UPPER JET AS A MORE DEFINED FRONT MOVES
ACROSS WISCONSIN SOMETIME LATE FRIDAY/EARLY SATURDAY. THIS WILL BE
ANOTHER OPPORTUNITY FOR RAIN AND THUNDERSTORMS, POSSIBLY STRONG TO
SEVERE.
MEANWHILE, TEMPERATURES WILL TREND ABOVE NORMAL THROUGH THE
PERIOD, WITH DAILY HIGHS ANYWHERE FROM THE MID 70S TO UPPER 80S,
AND DAILY LOWS ANYWHERE FROM THE LOW 50S TO LOW 70S, WARMEST
TOWARDS NEXT WEEKEND.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1217 PM CDT SUN JUN 15 2025
CIGS HAVE RISEN TO VFR OVER THE FOX VALLEY AND EASTERN WI, WHILE
MVFR CIGS CONTINUE OVER CENTRAL AND NORTH-CENTRAL WI. EXPECT THESE
LOWER CLOUDS TO GRADUALLY RISE THIS AFTERNOON WITH PRIMARILY VFR
CONDITIONS LATE THIS AFTERNOON AND EVENING.
EXPECT MVFR CLOUDS TO REESTABLISH TONIGHT, MAINLY OVER CENTRAL AND
NORTHERN WI. FORECAST SOUNDINGS ALSO SHOW SOME INDICATION A PERIOD
OF IFR CIGS IS POSSIBLE EARLY MONDAY MORNING, HOWEVER, CONFIDENCE IN
THESE LOWER CIGS OCCURRING IS LOW SO WENT WITH LOW-END MVFR AT
AUW/CWA/RHI. MODELS ALSO SHOW A CHANCE (20-30%) FOR LIGHT SHOWERS
OVERNIGHT ACROSS CENTRAL AND NORTHERN WI, BUT AVIATION IMPACTS FROM
ANY SHOWERS SHOULD BE MINOR.
LIGHT EASTERLY WINDS WILL REMAIN FOR THE REST OF TODAY BEFORE
VEERING AROUND TO THE SOUTH EARLY MONDAY MORNING.
BEYOND THE TAF PERIOD THERE IS AN INCREASE CHANCE FOR AN AREA OF
THUNDERSTORMS TO MOVE INTO CENTRAL AND NORTHERN WI LATE MONDAY
AFTERNOON/EVENING. SOME STRONGER THUNDERSTORMS ARE POSSIBLE WITH
STRONG WIND GUSTS (40-50 MPH) THE MAIN EXPECTED HAZARD.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK/KLJ
AVIATION.......GK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page