747
FXUS63 KGRB 191917
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
217 PM CDT TUE AUG 19 2025
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
KEY MESSAGES
- PATCHY DENSE FOG OVERNIGHT TONIGHT THROUGH DAYBREAK ON
WEDNESDAY, ESPECIALLY CENTRAL AND NORTH-CENTRAL WISCONSIN.
- ISOLATED SHOWERS ARE POSSIBLE AT TIMES THROUGH WEDNESDAY. THE
REST OF THE WEEK WILL BE DRY WITH THE NEXT CHANCE FOR SHOWERS
AND THUNDERSTORMS FRIDAY INTO FRIDAY NIGHT. SEVERE STORMS ARE
NOT EXPECTED.
- TEMPERATURES WILL BE AROUND NORMAL FOR MUCH OF THE UPCOMING WEEK,
WITH THE POTENTIAL FOR WELL BELOW NORMAL TEMPERATURES LATE IN
THE WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 211 PM CDT TUE AUG 19 2025
LOW AMPLITUDE SHORTWAVE TROUGH IN NORTHWEST FLOW ALONG WITH
ONGOING COLD AIR ADVECTION WILL RESULT IN SMALL CHANCES FOR
SHOWERS THROUGH WEDNESDAY. HIGH PRESSURE CENTERED OVER NORTHERN
MN AND WESTERN LAKE SUPERIOR THROUGH WEDNESDAY WITH LOW PRESSURE
CROSSING THE LOWER GREAT LAKES WILL LEAD TO GENERAL NORTHEAST
LOW-LEVEL WINDS, WITH CONVERGENCE MAXIMIZED NEAR BAY OF GREEN BAY
AND LAKE MICHIGAN. IT WILL BE IN THIS ZONE, WHERE THE SHOWER
CHANCES WILL BE MAXIMIZED ON WEDNESDAY. RAINFALL AMOUNTS WILL BE
VERY LIGHT, WELL UNDER 0.25 INCH THROUGH WEDNESDAY. GIVEN THE
COOLER AIR FLOWING ACROSS THE LAKES (+12C AT 850MB/5KFT), TOOK A
GLACE AT POTENTIAL LAKE EFFECT PROCESSES AIDING IN THE SHOWERS,
BUT EVEN WITH WATER TEMPS ON THE LAKE AND THE BAY AROUND 68-72F
(20-21C), DELTA T/S STAY BELOW THRESHOLD OF 13C WHICH IS TYPICALLY
WHAT IS NEEDED TO SEE EVEN A WEAKER LAKE RESPONSE. THIS ALSO KEEPS
US OUT OF ANY RANGE FOR POTENTIAL WATERSPOUTS, FOR NOW.
OTHER ISSUE THROUGH WEDNESDAY WILL BE PATCHY DENSE FOG LATE TONIGHT
INTO EARLY WEDNESDAY. USING THE HREF DATA, HIGHEST RISK OF VISIBILITY
LESS THAN 1 MILE (30-60%) IS LOCATED OVER CENTRAL AND NORTH-CENTRAL
WI. ADDED MENTION OF PATCHY DENSE FOG TO THE HWO. TEMPS TONIGHT
WILL DROP INTO THE 50S NORTH-CENTRAL INTO FAR NORTHEAST WI. HIGHS
ON TUESDAY WILL MOSTLY RISE TO THE MIDDLE TO UPPER 70S.
LOOKING AHEAD, AFTER A COUPLE DAYS OF DRY WEATHER LATER WED THROUGH
THU THANKS TO CANADIAN HIGH PRESSURE, APPROACHING COLD FRONT BRINGS
NEXT CHANCE OF SHOWERS AND STORMS ACROSS THE REGION ON FRIDAY.
INSTABILITY AND SHEAR SHOWN BY LREF COULD SUPPORT ISOLATED STRONG
STORM IF THIS FROPA OCCURS DURING MAX HEATING ON FRIDAY AFTERNOON,
BUT SEVERE STORMS ARE NOT EXPECTED. BEHIND THE FRONT, NEXT WEEKEND
LOOKS MORE FALL-LIKE WITH HIGHS BY NEXT SUNDAY PERHAPS NOT EVEN
REACHING 70. SKIES WILL PARTLY TO MOSTLY CLOUDY WITH CU AND
STRATOCU AND IT MAY BE BREEZY AT TIMES. FORECAST CURRENTLY WILL
CARRY SMALL CHANCE OF SHOWERS ON SUNDAY, ESPECIALLY NORTH AND
NORTHEAST. PATTERN WOULD SUGGEST THAT LATER FORECASTS MAY END UP
SHOWING HIGHER CHANCE FOR SHOWERS ESPECIALLY SATURDAY OVER THE
NORTH AND ON SUNDAY FOR ALL AREAS, ALONG WITH AN INCREASE IN
CLOUD COVER. FURTHER INCREASE IN THE SHOWERS MAY BE DUE TO LAKE
EFFECT AS 850MB TEMPS BOTTOM OUT AT 5-6C. THE TASTE OF FALL WILL
LAST THROUGH EARLY NEXT WEEK.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1244 PM CDT TUE AUG 19 2025
CEILINGS ARE GRUDGINGLY LIFTING TO MAINLY MVFR. EXPECT ADDITIONAL
IMPROVEMENT TO LOWER VFR BY LATE AFTERNOON. A FEW SHOWERS MAY OCCUR
AT RHI INTO EARLY EVENING. LATER TONIGHT, ANOTHER ROUND OF LOW CIGS
ARE EXPECTED, WITH LIFR-IFR CATEGORY CENTRAL TO NORTH-CENTRAL AND
MVFR ELSEWHERE. FOG EXPECTED WITH IFR-MVFR VSBY CENTRAL TO NORTH-
CENTRAL WI, WITH VSBY AS LOW AS LIFR OVER NORTH-CENTRAL (RHI). ON
WEDNESDAY, EVEN ONCE THE FOG LIFTS, EXPECT LOW CIGS TO PERSIST
THROUGH THE REST OF TAF PERIOD. A FEW SHOWERS COULD OCCUR ON WED
MORNING AT MTW.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....JLA
AVIATION.......JLA
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