507
FXUS63 KGRB 211925
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
225 PM CDT TUE OCT 21 2025
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST 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 PATTER 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 18Z TAF ISSUANCE
ISSUED AT 1247 PM CDT TUE OCT 21 2025
MIX OF VFR/MVFR CIGS ACROSS THE REGION EARLY THIS AFTERNOON. ALONG
WITH THE LOWER CIGS SCATTERED SHOWERS ARE DEVELOPING SOUTH OF AN IMT
TO RHI LINE. AS A SURFACE LOW CONTINUED TO SPIN OVER THE WESTERN
GREAT LAKES THIS AFTERNOON AND EVENING SHOWER ACTIVITY WILL CONTINUE
TO INCREASE ACROSS MOST OF THE REGION. VSBYS ARE WILL GENERALLY
REMAIN VFR, HOWEVER, BRIEF PERIODS OF MVFR VSBYS ARE POSSIBLE AS
SHOWERS PASS DIRECTLY OVER ANY TERMINALS.
CIGS ARE EXPECTED TO GRADUALLY DESCEND TONIGHT WITH BLANKET MVFR/IFR
CIGS EXPECTED EARLY WEDNESDAY MORNING. IFR CIGS ARE MOSTLY LIKELY AT
AUW, CWA, AND RHI
SOUTHWEST TO WEST WINDS WILL ALSO REMAIN BREEZY THROUGH THIS EVENING
WITH PERIODIC GUSTS OF 20-25KTS POSSIBLE ACROSS MUCH OF OF THE
REGION.
SCATTERED SHOWERS WILL CONTINUE WEDNESDAY AS BREEZY NORTHWEST WINDS
OFF LAKE SUPERIOR INDUCE SOME LAKE EFFECT SHOWERS. COVERAGE OF
SHOWERS WILL BE GREATEST ACROSS NORTHERN WI.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK
AVIATION.......GK
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