991
FXUS63 KGRB 092355
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
655 PM CDT SAT MAY 9 2026
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
KEY MESSAGES
- LOW AFTERNOON HUMIDITIES ARE EXPECTED SUNDAY AND MONDAY.
- A FROST ADVISORY HAS BEEN ISSUED FOR AREAS OVER CENTRAL
WISCONSIN AND WEST OF THE FOX VALLEY FOR EARLY SUNDAY MORNING.
ADDITIONAL FROST IS LIKELY SUNDAY NIGHT INTO EARLY MONDAY
MORNING.
- HIGH PROBABILITY OF RAIN ON TUESDAY (GREATER THAN 80%). A FEW
ISOLATED THUNDERSTORMS ARE POSSIBLE OVER CENTRAL AND NORTHEAST
WISCONSIN AS THE SYSTEM PASSES.
DISCUSSION
ISSUED AT 116 PM CDT SAT MAY 9 2026
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DEEP
UPPER TROUGH CENTERED FROM HUDSON BAY TO THE CENTRAL GREAT LAKES
EARLY THIS AFTERNOON. EMBEDDED SHORTWAVE ENERGY IS PUSHING A COLD
FRONT ACROSS LAKE MICHIGAN WITH SCATTERED LIGHT SHOWER ACTIVITY
EXITING TO THE EAST. PARTIAL CLEARING IS SPREADING ACROSS
NORTHWEST WISCONSIN AND THIS CLEARING TREND SHOULD CONTINUE EAST
THROUGH THE REST OF THE AFTERNOON. LOOKING FURTHER UPSTREAM, A
RIDGE OF HIGH PRESSURE IS POSITIONED OVER THE PLAINS AND IS
GRADUALLY SHIFTING EASTWARD. FORECAST CONCERNS REVOLVE AROUND
FIRE WEATHER POTENTIAL, FROST POTENTIAL, AND LIGHT RAIN CHANCES.
AS SKIES CLEAR THIS EVENING AND WINDS BECOME LIGHT UNDER THE
INFLUENCE OF THE APPROACHING SURFACE RIDGE, FAVORABLE RADIATIONAL
COOLING CONDITIONS WILL DEVELOP. THIS WILL SET THE STAGE FOR
FROST DEVELOPMENT. WHILE THERE IS SOME CONCERN THAT THE PRESSURE
GRADIENT MAY STAY TIGHT ENOUGH TO KEEP TEMPERATURES UP SLIGHTLY,
CONSENSUS GUIDANCE IS INSISTENT ON LOWS IN THE MIDDLE 30S FOR
AREAS WEST OF THE FOX VALLEY. CONSEQUENTLY, A FROST ADVISORY HAS
BEEN ISSUED FOR MUCH OF CENTRAL WISCONSIN AND WEST OF OUTAGAMIE
AND WINNEBAGO COUNTIES.
ON SUNDAY, CLOUDS WILL REDEVELOP WITH THE HEAT OF THE DAY.
MARGINALLY UNSTABLE CONDITIONS OFF LAKE SUPERIOR COMBINED WITH
WEAK SHORTWAVE IMPULSES COULD LEAD TO WIDELY SCATTERED LIGHT
SHOWERS OR SPRINKLES ACROSS FAR NORTH- CENTRAL AND NORTHEAST
WISCONSIN SUNDAY AFTERNOON, THOUGH AMOUNTS WILL BE NEGLIGIBLE.
ANOTHER ROUND OF FROST APPEARS LIKELY SUNDAY NIGHT AS HIGH
PRESSURE SETTLES DIRECTLY OVER THE STATE.
THE NEXT SIGNIFICANT WEATHER MAKER ARRIVES ON TUESDAY IN THE FORM
OF A DYNAMIC CLIPPER SYSTEM. CONFIDENCE IN PRECIPITATION HAS
INCREASED SIGNIFICANTLY, WITH RAIN CHANCES NOW EXCEEDING 80
PERCENT. MID-LEVEL LAPSE RATES OF 6.5 TO 7 C/KM WILL SUPPORT
MODEST INSTABILITY, MAKING ISOLATED THUNDERSTORMS A POSSIBILITY
OVER CENTRAL AND NORTHEAST WISCONSIN. SHOWERS MAY LINGER INTO
TUESDAY NIGHT, PARTICULARLY ACROSS THE FAR NORTH, BEFORE THE
SYSTEM EXITS TO THE EAST.
A SHIFT IN THE LARGE-SCALE PATTERN IS EXPECTED LATE NEXT WEEK AS
THE PERSISTENT EASTERN TROUGH FLATTENS AND A WARMING RIDGE OVER
THE WESTERN UNITED STATES SHIFTS EASTWARD. THIS WILL RESULT IN A
PRONOUNCED WARMING TREND STARTING THURSDAY, WITH HIGH TEMPERATURES
LIKELY REACHING THE 70S TO NEAR 80 DEGREES BY NEXT SATURDAY. THIS
WARMER AIRMASS WILL LEAD TO INCREASING INSTABILITY BY THE END OF
NEXT WEEKEND, THOUGH UNCERTAINTY REMAINS REGARDING THE TIMING OF
THE NEXT ROUND OF ORGANIZED PRECIPITATION.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 652 PM CDT SAT MAY 9 2026
PRIMARY LOW PRESSURE RESIDES OVER QUEBEC THIS EVENING, LEAVING
NORTHEAST WI WITHIN A COOL, MOIST NORTHWEST FLOW ALOFT. WEAK WAVES
WITHIN THE PATTERN THROUGH SUNDAY WILL RESULT IN SCT-BKN HIGH-
BASED (CIGS 050-100) STRATOCU CLOUDS WITH SMALL CHANCES (<15%) OF
SPRINKLES/FLURRIES THIS EVENING NORTH-CENTRAL, THEN SPRINKLES OR
A LIGHT SHOWER OVER MAINLY NORTHEAST WI ON SUNDAY FROM LATE MORNING
THROUGH MID AFTERNOON. CONDITIONS WILL REMAIN VFR.
NW WINDS WILL BE GUSTY THROUGH 01Z-02Z THIS EVENING, THEN BECOME
LIGHT THROUGH THE OVERNIGHT HOURS. NW WINDS WILL INCREASE AGAIN ON
SUNDAY, GUSTING TO AROUND 20 KTS LATE MORNING THROUGH MID AFTERNOON.
WINDS WILL BECOME CALM SUNDAY EVENING AS HIGH PRESSURE SETTLES DIRECTLY
OVERHEAD.
FIRE WEATHER
ISSUED AT 116 PM CDT SAT MAY 9 2026
ELEVATED FIRE WEATHER CONDITIONS ARE THE PRIMARY CONCERN THROUGH
THE REMAINDER OF THE AFTERNOON. A DRY AIRMASS IS IN PLACE BEHIND
THE DEPARTING COLD FRONT. DEEP MIXING WILL ALLOW DEWPOINTS TO
DROP, RESULTING IN MINIMUM RELATIVE HUMIDITIES IN THE 25 TO 35
PERCENT RANGE AWAY FROM THE IMMEDIATE LAKE MICHIGAN SHORELINE.
COMBINED WITH NORTHWEST WIND GUSTS OF 25 TO 30 MPH, CONDITIONS
WILL BE FAVORABLE FOR FIRE DEVELOPMENT. WINDS WILL DIMINISH THIS
EVENING WITH THE ONSET OF NOCTURNAL COOLING, PROVIDING SOME
REPRIEVE. LOW AFTERNOON HUMIDITIES ARE ALSO EXPECTED ON SUNDAY
AND MONDAY THOUGH WINDS WILL BE LESS THAN TODAY.
GRB WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM 3 AM TO 8 AM CDT SUNDAY FOR WIZ030-031-
035>037-045.
DISCUSSION.....MPC
AVIATION.......JLA
FIRE WEATHER...MPC
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