318
FXUS63 KGRR 081758
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
158 PM EDT FRI AUG 8 2025
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS EARLY NEXT WEEK
DISCUSSION
ISSUED AT 218 AM EDT FRI AUG 8 2025
- SHOWERS AND THUNDERSTORMS EARLY NEXT WEEK
MOSTLY QUIET WEATHER EXPECTED TO CONTINUE THROUGH SUNDAY UNDER
A BUILDING UPPER RIDGE. A GENERAL PATTERN OF WARM AIR
ADVECTION/ISENTROPIC ASCENT CONTINUES TODAY WITH ISOLATED SHOWERS
AND THUNDERSTORMS EXPECTED ACROSS THE NORTHERN FORECAST AREA AS
AN AREA OF SHOWERS WITH ISOLATED HEAVY DOWNPOURS CURRENTLY NEAR
MUSKEGON MOVES NORTHEAST THROUGH DAYBREAK.
THE UPPER RIDGE IS EVENTUALLY REPLACED BY HEIGHT FALLS EARLY NEXT
WEEK AS A SLOW MOVING TROUGH ADVANCES EAST FROM THE NORTHERN
PLAINS INTO THE GREAT LAKES. A SFC TROUGH/COLD FRONT SLOWLY SAGS
INTO LOWER MICHIGAN FROM THE NORTHWEST LATE SUNDAY THROUGH
WEDNESDAY INTO A WEAKLY SHEARED ENVIRONMENT WITH DEEP MOISTURE
AND MODEST INSTABILITY.
SEVERE THREAT IS LOW AND MAINLY FOR ISOLATED WET MICROBURSTS.
P-WATS NEAR 2 INCHES AND STORM MOTION FROM MBE VELOCITY PROGGED TO
BE LESS THAN 5 KNOTS SUGGEST EXCESSIVE RAINFALL THREAT FOR
LOCALIZED FLOODING EXISTS AS WELL.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 158 PM EDT FRI AUG 8 2025
VFR CUMULUS CLOUD BASES THROUGH THIS EVENING WITH SOUTH-SOUTHWEST
WINDS. WILL BE WATCHING FOR SHOWERS OR THUNDERSTORM CELLS POPPING
UP IN A ZONE BETWEEN GRR, MOP, AND LAN BETWEEN 19 AND 01 Z. SOME
MODELS ATTEMPT TO DEVELOP SHOWERS/THUNDERSTORMS IN THAT ZONE,
WHERE A RELATIVELY DENSE CUMULUS CLOUD FIELD AND WIND CONFLUENCE
EXISTS CURRENTLY. IF A MORE ROBUST CONVECTIVE CELL DEVELOPS, IT
COULD PRODUCE HAIL ALOFT AND MICROBURSTS RESULTING IN LLWS AND
SURFACE WIND GUSTS GREATER THAN 30 KNOTS.
MARINE
ISSUED AT 218 AM EDT FRI AUG 8 2025
SOUTH WINDS WILL INCREASE TODAY AND TONIGHT AND A SMALL CRAFT
ADVISORY WILL LIKELY BE NEEDED NORTH OF HOLLAND OR GRAND HAVEN FOR
SATURDAY. THE CHANCE FOR STRONG THUNDERSTORMS WILL INCREASE ON
SUNDAY NIGHT INTO MONDAY, ESPECIALLY NORTH OF GRAND HAVEN.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...OSTUNO
AVIATION...CAS
MARINE...OSTUNO
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