820
FXUS63 KGRB 230303
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1003 PM CDT WED OCT 22 2025
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
KEY MESSAGES
- ON AND OFF RAIN SHOWERS REMAIN THROUGH TONIGHT. LAKE EFFECT
SHOWERS LATE TONIGHT INTO THURSDAY MORNING POTENTIALLY MIXING
WITH THE SEASONS FIRST SNOWFLAKES OVER FAR NORTH-CENTRAL
WISCONSIN.
- A FROST OR FREEZE IS EXPECTED OVER THE FOX VALLEY AND LAKESHORE
AREAS ON THURSDAY NIGHT, LIKELY ENDING THE GROWING SEASON.
- BELOW NORMAL TEMPERATURES ARE EXPECTED THROUGH THURSDAY FOLLOWED
BY A SLOW WARMING TREND INTO THE WEEKEND.
DISCUSSION
ISSUED AT 203 PM CDT WED OCT 22 2025
TONIGHT THROUGH FRIDAY...
CYCLONIC FLOW ALONG WITH DAYTIME HEATING HAS INCREASED RAIN SHOWER
ACTIVITY ACROSS THE REGION THIS AFTERNOON. EXPECT THIS ACTIVITY TO
BEGINNING WANING THIS EVENING, EXCEPT ACROSS NORTH-CENTRAL WISCONSIN
WHERE NORTHWEST WINDS OFF WESTERN LAKE SUPERIOR WILL CONTINUE TO
PRODUCE SCATTERED LAKE EFFECT SHOWERS THROUGH THE EVENING. THE
PROBABILITY FOR A FEW SNOWFLAKES TO MIX IN WITH THE RAIN HAS
INCREASED ACROSS FAR NORTH-CENTRAL WI TONIGHT TO AROUND 30-35%.
FAVORABLE WIND TRAJECTORIES, DELTA-TS OF 15-17C, AND HIGH MID-LEVEL
RELATIVE HUMIDITIES WITH LAKE INDUCED EQUILIBRIUM LEVELS UP TO
12,000FT ALL SUPPORT AREAS IN NORTH-CENTRAL WI SEEING THE FIRST
SNOW OF THE SEASON. HOWEVER, WITH GROUND TEMPERATURES ABOVE
FREEZING AND LOW TEMPERATURES HOVERING AT OR JUST ABOVE FREEZING
EXPECT MINIMAL IF ANY ACCUMULATIONS. AS THE SURFACE LOW PULLS
FURTHER TO THE EAST THURSDAY ANY LINGERING PRECIPITATION SHOULD
COME TO AN END DURING THE AFTERNOON.
AS SKIES CLEAR OUT BEHIND THE DEPARTING LOW THURSDAY NIGHT
TEMPERATURES ARE EXPECTED TO FALL NEAR OR BELOW FREEZING ACROSS MOST
OF THE REGION. CONFIDENCE IS LOWEST IN A FREEZE ACROSS EAST-CENTRAL
WISCONSIN WHERE WINDS MAY NOT DECOUPLE ENTIRELY. THIS MAY KEEP LOWS
JUST ABOVE FREEZING FOR PARTS OF THOSE AREAS.
SATURDAY INTO MID NEXT WEEK...
GENERALLY LOW IMPACT WEATHER IS EXPECTED THIS WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. A RIDGE DEVELOPING OVER THE CENTRAL CONUS WILL
BRING MOSTLY DRY CONDITIONS TO THE REGION THROUGH THIS WEEKEND.
HOWEVER, A SMALL NUMBER (~10%) OF LREF ENSEMBLE MEMBERS DO SHOW A
TRANSIENT SHORT-WAVE SWINGING ACROSS THE REGION EARLY SATURDAY,
WHICH COULD SPUR ON A FEW SHOWERS, BUT EVEN IF A FEW SCATTERED
SHOWERS DO DEVELOP ONLY EXPECT MINIMAL RAINFALL AMOUNTS. THE NEXT
CHANCE FOR AREA WIDE PRECIPITATION IS EXPECTED EARLY NEXT WEEK AS
A BROAD NEGATIVELY TILTED TROUGH DEVELOPS OVER THE WESTERN CONUS
CREATING FAVORABLE CONDITIONS FOR CYCLOGENESIS ACROSS THE WESTERN
GREAT LAKES. THERE IS CONSIDERABLE UNCERTAINTY WITH THE TIMING AND
INTENSITY OF PRECIPITATION WITH THIS SYSTEM AS RECENT RUNS OF THE
GFS/GEFS ARE FAR MORE PROGRESSIVE AND WETTER THAN THE ENS AND
CANADIAN ENSEMBLES. DESPITE DIFFERENCES IN THE ENSEMBLES, IMPACTS
FROM THIS SYSTEM ARE EXPECTED TO BE MINIMAL. INSTABILITY IS
EXPECTED TO BE SHUNTED WELL TO THE SOUTH, LIMITING THE THUNDERSTORM
POTENTIAL. 540 THICKNESSES ARE ALSO EXPECTED TO REMAIN WELL
NORTH, LIMITING THE POTENTIAL FOR ANY FREEZING PRECIPITATION.
TEMPERATURES WILL BEGIN A SLIGHT WARMING TRENDING THIS WEEKEND WITH
HIGHS NEAR TO JUST ABOVE NORMAL. TEMPERATURES THEN LOOK TO REMAIN
STEADILY NEAR NORMAL THROUGH THE SECOND HALF OF NEXT WEEK.
AVIATION
FOR 06Z TAF ISSUANCE
ISSUED AT 1003 PM CDT WED OCT 22 2025
LAKE EFFECT SHOWERS CONTINUE OVER NORTHERN WI, INCLUDING AT RHI,
BUT OTHERWISE HAVE DIMINISHED OVER THE REST OF THE AREA. EXPECT
MAINLY VFR CONDITIONS THE REST OF THE NIGHT FROM CENTRAL TO EAST-
CENTRAL WI. MEANWHILE, IFR TO LOWER MVFR CONDITIONS WILL PERSIST
OVER NORTHERN WI.
ON THURSDAY, AS COLDEST AIR ALOFT MOVES OVERHEAD, STILL LIKE
FEW HOUR PERIOD OF MAINLY SNOW AT RHI CENTERED AROUND 14Z (IFR
VSBY POSSIBLE), BEFORE THE LAKE EFFECT SHOWERS START TO END. IT
SHOULD STAY DRY ELSEWHERE. CIGS WILL STAY MVFR OVER THE NORTH
(RHI), FEATURE A MIX OF MVFR AND VFR OVER CENTRAL WI (AUW/CWA),
AND STAY VFR FOX VALLEY TO THE LAKESHORE (GRB/ATW/MTW). SKIES WILL
FINALLY START TO CLEAR OUT ON THURSDAY EVENING, THOUGH LOWER VFR
CIGS WILL PROBABLY HANG ON AT RHI TIL THE END OF THE TAF PERIOD.
NORTHWEST WINDS WILL BE LIGHT TONIGHT, BUT WILL START TO GUST TO
AROUND 15 KTS MID MORNING INTO MID AFTERNOON. WINDS WILL BECOME
LATE THURSDAY AFTERNOON, SETTING THE STAGE FOR WIDESPREAD FROST OR
FREEZE ON THURSDAY NIGHT.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK
AVIATION.......JLA
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