590
FXUS63 KGRB 160405
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1105 PM CDT SUN JUN 15 2025
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
KEY MESSAGES
- A WARM, HUMID, AND STORMY PERIOD IS EXPECTED THROUGH MID-WEEK,
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 06Z TAF ISSUANCE
ISSUED AT 1054 PM CDT SUN JUN 15 2025
MAINLY DRY CONDITIONS WERE OBSERVED ACROSS THE FORECAST AREA LATE
THIS EVENING. VFR CONDITIONS PREVAILED OVER THE SOUTHEAST HALF OF
THE FORECAST AREA, WITH MVFR OBSERVED NORTHWEST.
EXPECT VFR CONDITIONS TO PREVAIL AT THE EASTERN TAF SITES THROUGH
MUCH THE TAF PERIOD. MVFR CONDITIONS REMAIN LIKELY AT THE WESTERN
TAF SITES, WITH A POSSIBLE LOWERING TO IFR EARLY MONDAY MORNING,
FOLLOWED BY IMPROVEMENT TO VFR AFTER A WARM FRONT MOVES THROUGH
IN THE LATE MORNING/EARLY AFTERNOON. REGARDING PRECIPITATION
CHANCES, OVERALL CONFIDENCE HAS DECREASED DUE TO A LACK OF
AGREEMENT WITH THE LATEST MODEL RUNS. WILL CONTINUE WITH OUR
PREVIOUS THINKING, STARTING WITH A CHANCE OF SHOWERS AND POSSIBLY
A THUNDERSTORM IN C/NC WI AS AN MCV IN MN MOVES THROUGH MONDAY
MORNING. THERE IS LESS CONFIDENCE FARTHER EAST, SO WILL CONTINUE
WITH A PROB30 FOR SHOWERS AT THE EASTERN SITES DURING THE LATE
MORNING/EARLY AFTERNOON. STILL THINK IT IS POSSIBLE FOR A ROUND OF
THUNDERSTORMS ARRIVING IN NC/C WI EARLY MONDAY EVENING, THEN
TRACKING INTO THE EASTERN TAF SITES TOWARD THE END OF THE PERIOD.
LIGHT EASTERLY WINDS WILL GRADUALLY TURN SOUTHEAST OVERNIGHT, THEN
BECOME A BIT GUSTY FROM THE SOUTH AFTER THE WARM FRONT MOVES
THROUGH ON MONDAY.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK/KLJ
AVIATION.......KIECKBUSCH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page