878
FXUS63 KGRB 090410
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1110 PM CDT WED APR 8 2026
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
UPDATE
ISSUED AT 946 PM CDT WED APR 8 2026
SWATH OF RAIN JUST AHEAD OF COLD FRONT IS QUICKLY SHIFTING EAST
THIS EVENING, PRETTY MUCH ON TRACK WITH GOING FORECAST. NO THUNDER
YET, BUT STILL COULD HAVE A RUMBLE OF THUNDER THROUGH MIDNIGHT
OVER EASTERN WI. GUSTY SOUTH WINDS FROM EARLIER THAT GUSTED TO
AROUND 50 MPH HAVE DIMINISHED. DO EXPECT A PUSH OF GUSTY W/NW
WINDS LATER TONIGHT THROUGH DAYBREAK ON THURSDAY BEHIND THE FRONT.
RAINFALL AMOUNTS HAVE STAYED IN CHECK THUS FAR, WITH MOST AMOUNTS
UNDER 0.25 INCH, AND ISOLATED SPOTS 0.30-0.40 INCH.
AS THE WINDS HAVE DIMINISHED, HAVE DROPPED THE GALE WARNING ON
LAKE MICHIGAN.
KEY MESSAGES
- POTENTIAL FOR HEAVY RAINFALL AND THUNDERSTORMS THIS WEEKEND INTO
EARLY NEXT WEEK. 1 TO 1.5" OF QPF EXPECTED, WITH UP TO 2"
POSSIBLE IN SPOTS. STRONG OR SEVERE THUNDERSTORMS THEN POSSIBLE
MONDAY INTO TUESDAY.
- MINOR FLOODING CONTINUES ALONG A FEW RIVERS, THOUGH RUNOFF FROM
MELTING SNOW IN THE UPPER PENINSULA PAIRED WITH HEAVY RAIN MAY
RESULT IN MORE WIDESPREAD AND SIGNIFICANT FLOODING THIS WEEKEND
INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 958 AM CDT WED APR 8 2026
RADAR SHOWS ANY REMNANTS OF THE WINTRY MIX FROM THIS MORNING
DEPARTING THE AREA TO THE EAST AS OF EARLY THIS AFTERNOON.
HOWEVER, WE WILL ONLY BE AFFORDED A BRIEF DRY SPELL BEFORE BETTER
SATURATION RETURNS LATE THIS AFTERNOON INTO THIS EVENING WITH THE
PASSAGE OF A POTENT MID-LEVEL SHORTWAVE AND TANDEM COLD FRONT.
THIS SHOULD BRING AN ADDITIONAL 0.25 TO 0.5" OF QPF ACROSS THE
FORECAST AREA THROUGH THURSDAY MORNING. NARROW CORRIDOR OF
ELEVATED INSTABILITY (200 TO 300 J/KG) RIGHT ALONG THE FRONT
WOULD SUGGEST THAT A RUMBLE OR TWO OF THUNDER WOULDN'T BE OUT OF
THE QUESTION THIS EVENING, THOUGH NO ORGANIZED STORMS ARE
EXPECTED.
TRANSIENT SHORTWAVE ENERGY PAIRED WITH MID-LEVEL FGEN WILL BRING
ANOTHER QUICK-HITTING ROUND OF LIGHT RAIN TO NORTHEAST WISCONSIN
THURSDAY NIGHT INTO FRIDAY MORNING. MOST AREAS SHOULD SEE UNDER A
TENTH OF QPF, WITH HIGHEST AMOUNTS APPROACHING 0.2" OVER EAST-
CENTRAL WISCONSIN.
WEEKEND RAIN/STORM CHANCES... PREVAILING SOUTHERLY FLOW AND A
WIDE OPEN GULF WILL PROMOTE A PERIOD OF PROLONGED ACTIVE WEATHER
THROUGH NEXT WEEK. OF PARTICULAR CONCERN WILL BE THE MONDAY INTO
TUESDAY PERIOD AS A DEEPENING SURFACE LOW AND ATTENDANT COLD
FRONT TRACK THROUGH THE UPPER MISSISSIPPI VALLEY. PWATS RANGING
FROM 1 TO 1.25" WOULD SUPPORT A DECENT PERIOD OF MODERATE TO HEAVY
RAIN DURING THIS TIME, WITH PROBABILISTIC GUIDANCE SHOWING A 10
TO 30% CHANCE FOR RECEIVING 1.5" OF QPF THROUGH TUESDAY MORNING.
MODEST INSTABILITY (~1,000 TO 1,200 J/KG MUCAPE) AND APPRECIABLE
DEEP LAYER SHEAR (45 TO 55 KNOTS) MAY RESULT IN THE DEVELOPMENT OF
STRONG OR EVEN SEVERE STORMS LATE MONDAY INTO TUESDAY, THOUGH
THERE ARE STILL TIMING DISCREPANCIES WITHIN THE ENSEMBLES
REGARDING COLD FROPA. THIS WOULD LIKELY MAKE A DIFFERENCE IN
WHETHER OR NOT SURFACE-BASED STORMS WOULD BE ABLE TO DEVELOP, AND
IS WORTH MONITORING IN THE COMING DAYS. REGARDLESS, CSU AND NCAR
MACHINE LEARNING ALGORITHMS HIGHLIGHT MUCH OF THE UPPER MIDWEST IN
A 15 TO 30% PROB SEVERE OUT TO DAY 6.
AVIATION
FOR 06Z TAF ISSUANCE
ISSUED AT 1110 PM CDT WED APR 8 2026
RAIN SHOWERS EXIT EASTERN WI AROUND THE START OF TAF TIME.
CONDITIONS WILL REMAIN VFR. SURFACE WINDS WILL BECOME NOT AS GUSTY
THE REST OF THE NIGHT AS WINDS SHIFT FROM S/SW TO W. LLWS TO
START, BUT EVENTUALLY TOWARD DAYBREAK ON THURSDAY THE LLWS WILL
END.
LATE TONIGHT INTO THURSDAY MORNING, SCT-BKN MVFR STRATOCU CLOUDS
WILL MOVE INTO CENTRAL AND NORTH-CENTRAL WI (RHI, AUW, CWA). THE
GREATEST CHANCES FOR PREVAILING MVFR CIGS WILL BE AT RHI TOWARD
THE UPPER MICHIGAN BORDER. ELSEWHERE, SCATTERED VFR CLOUDS WILL
PREVAIL THROUGH THE DAY. AFTER A PUSH OF GUSTY W WINDS LATE
TONIGHT THROUGH DAYBREAK, WINDS THE REST OF THE DAY WILL BE FROM
THE W/NW AND NOT AS GUSTY.
HYDROLOGY
ISSUED AT 958 AM CDT WED APR 8 2026
MINOR FLOODING CONTINUES ON THE WOLF RIVER, PERSISTING FOR THE
BETTER PART OF THE NEXT WEEK. FAST FLOWS AND BANKFULL CONDITIONS
WERE OBSERVED ELSEWHERE, NAMELY ON THE OCONTO, MENOMINEE, AND
WISCONSIN RIVERS. MOVING FORWARD, ACTIVE PATTERN WITH AMPLE
MOISTURE SUPPLY WILL CONTINUE TO RESULT IN HYDRO CONCERNS FOR THE
FORESEEABLE FUTURE, ESPECIALLY WITH PWATS NEARING ABSOLUTE MAX
RELATIVE TO CLIMO WITH THE PASSAGE OF ANOTHER SYSTEM THIS
WEEKEND. PROBABILITIES FOR RECEIVING 1.5" OF QPF CURRENTLY RANGE
FROM 10 TO 30% DURING THIS TIME, WHICH WOULD ONLY EXACERBATE SOIL
SATURATION AND PROMOTE RUNOFF. CONVECTIVELY-ENHANCED RAINFALL
WOULD ALSO SUPPORT RIVER/STREAM RISES EARLY NEXT WEEK. AREA OF
PARTICULAR CONCERN LOOKS TO BE THE MENOMINEE RIVER AND ITS
TRIBUTARIES, WHERE A SIGNAL FOR MINOR AND EVEN MODERATE FLOODING
EXISTS DUE TO THE ADDITIONAL INFLUENCE OF SNOWMELT FROM THE UPPER
PENINSULA.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE.........JLA
DISCUSSION.....GOODIN
AVIATION.......JLA
HYDROLOGY......GOODIN
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