245
FXUS63 KGRB 212331
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
631 PM CDT TUE OCT 21 2025
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
KEY MESSAGES
- ON AND OFF RAIN SHOWERS THIS EVENING THROUGH WEDNESDAY. LAKE
EFFECT SHOWERS WEDNESDAY NIGHT INTO THURSDAY POTENTIALLY MIXING
WITH THE SEASONS FIRST SNOWFLAKES OVER FAR NORTH-CENTRAL
WISCONSIN.
- GUSTY NORTHWEST WINDS UP TO 30 MPH ARE POSSIBLE THROUGH
WEDNESDAY, CREATING HAZARDOUS CONDITIONS FOR SMALL CRAFT ON
LAKE MICHIGAN AND GREEN BAY.
- BELOW NORMAL TEMPERATURES ARE EXPECTED THROUGH THURSDAY FOLLOWED BY
A SLOW WARMING TREND INTO THE WEEKEND.
DISCUSSION
ISSUED AT 224 PM CDT TUE OCT 21 2025
ON AND OFF RAIN SHOWERS THIS EVENING THROUGH WEDNESDAY...
CUT-OFF UPPER LOW, CURRENTLY CENTERED OVER OVER WESTERN LAKE
SUPERIOR, WILL CONTINUE TO SPUR ON SCATTERED SHOWERS THIS AFTERNOON
ACROSS THE REGION. SHOULD ACTIVITY SHOULD START TO SLOWLY WANE THIS
EVENING WITH THE LOSE OF DIURNAL HEADING. AS THE LOW SLOWLY PULLS OF
TO THE EAST WEDNESDAY A NORTHWEST FLOW REGIME WILL SETUP OVER THE
REGION LEADING TO SCATTERED LAKE INDUCED SHOWERS ACROSS MUCH OF THE
REGION, WITH THE GREATEST COVERAGE ACROSS NORTHERN WISCONSIN.
THERE IS A SLIGHT CHANCE (~10%) NORTH-CENTRAL WI SEES THE FIRST
SNOWFLAKES OF THE SEASON EARLY THURSDAY MORNING AS 850MB TEMPS FALL
TO -3-4C WHILE LAKE SURFACE TEMPERATUES REMAIN AROUND 12-14C.
FORECAST SOUNDINGS ALSO SHOW GREATER THAN 90% SATURATION IN THE 800-
700MB LAYER SUGGESTING THERE SHOULD BE SOME CONDENSATION NUCLEI
PRESENT. WITH SURFACE TEMPERATURES STILL ABOVE FREEZING DON'T EXPECT
ANY MEASURABLE ACCUMULATIONS.
ENSEMBLE UPPER-LEVEL HEIGHTS SUPPORT A SPLIT FLOW PATTERN DEVELOPING
THIS WEEKEND WITH RIDGING ACROSS EASTERN CANADA AND A SURFACE LOW
OVER THE SOUTHERN CONUS. THERE IS A SLIGHT CHANCE (10-20%) AREAS
SOUTH OF HWY 29 SEE SCATTERED SHOWERS SATURDAY INTO SUNDAY AS
BROAD WAA AND MOISTURE TRANSPORT MOVE OVER THE REGION, HOWEVER,
MID AND UPPER LEVEL MOISTURE PROFILES ARE PRETTY DRY, SO DON'T
EXPECT RAINFALL TOTALS TO BE THAT IMPRESSIVE. THE NEXT WIDESPREAD
CHANCE FOR PRECIPITATION PROGGED TO ARRIVE EARLY NEXT WEEK AS
ANOTHER BROAD LOW PRESSURE SYSTEM DEVELOPS OVER THE NORTHERN
CONUS, HOWEVER, THE SPECIFIC DETAILS REMAIN UNCERTAIN.
GUSTY NORTHWEST WINDS THROUGH WEDNESDAY...
RAP ANALYSIS SHOWS A CORE OF 40-45KT WINDS AT 850MB ACROSS
MINNESOTA/ IOWA THIS AFTERNOON, ASSOCIATED WITH A TIGHTENING PRESSURE
GRADIENT BEHIND THE LOW. AS THESE STRONGER WINDS MOVE EAST EXPECTED
GUSTS TO INCREASE TO 20-25KTS THIS EVENING AND OVERNIGHT.
BOATING HAZARDS: THE SMALL CRAFT ADVISORY REMAINS ON TRACK. WE WILL
NEED TO CONSIDER AN EXTENSION FOR WEDNESDAY EVENING, BUT CURRENT
GUIDANCE IS JUST SHY OF ADVISORY CRITERIA AT THAT TIME.
BELOW NORMAL TEMPERATURES ARE EXPECTED THROUGH THURSDAY...
THE PERSISTENT NORTHWEST FLOW WILL CONTINUE TO DELIVER BELOW NORMAL
TEMPERATURES TO THE REGION THROUGH THURSDAY. NBM PROBABILISTIC
GUIDANCE IS SUPPORTIVE OF A WIDESPREAD FREEZE THURSDAY NIGHT INTO
FRIDAY WITH FOR THE ENTIRE AREA, EXCEPT DOOR COUNTY WHERE LIGHT
WINDS OFF THE BAY MAY KEEP TEMPS JUST ABOVE FREEZING. PLEASE NOTE
THAT FROST/FREEZE CONSIDERATIONS ARE ONLY VALID OVER THE FOX VALLEY
AND LAKESHORE AREAS WHERE THE GROWING SEASON HAS NOT OFFICIALLY
ENDED.
A GRADUAL WARMING TREND IS EXPECTED THIS WEEKEND INTO EARLY NEXT
WEEK WITH TEMPERATURES RETURN TO NORMAL TO JUST ABOVE NORMAL.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 621 PM CDT TUE OCT 21 2025
THE EVENING STARTS OFF WITH SPOTTY SHOWERS EAST-CENTRAL WI WITH
STEADY LIGHT RAIN BEGINNING TO SHIFT INTO CENTRAL AND NORTH-
CENTRAL WI. CIGS ARE A MIX OF MVFR TO LOWER VFR, BUT WILL
GRADUALLY LOWER THROUGH THE NIGHT, WITH BLANKET MVFR/IFR CIGS
SETTLING ACROSS THE AREA. THE IFR CIGS ARE MOST LIKELY AT RHI.
SCATTERED SHOWERS WILL CONTINUE WEDNESDAY AS BREEZY NORTHWEST
WINDS OFF LAKE SUPERIOR PRODUCE SOME LAKE EFFECT SHOWERS.
COVERAGE OF SHOWERS WILL BE GREATEST ACROSS NORTHERN WI.
SOUTHWEST TO WEST WINDS WILL REMAIN BREEZY TONIGHT WITH PERIODIC
GUSTS OF 20-25KTS. NORTHWEST WINDS WILL REMAIN GUSTY ON WEDNESDAY
MORNING, BEFORE GRADUALLY DIMINISHING LATE IN THE DAY.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK
AVIATION.......JLA
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