387
FXUS63 KGRR 102356
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
756 PM EDT THU SEP 10 2026
KEY MESSAGES
- MOSTLY DRY THROUGH THIS WEEKEND
- RAIN AND THUNDERSTORMS POSSIBLE MONDAY THOUGH THURSDAY
DISCUSSION
ISSUED AT 219 PM EDT THU SEP 10 2026
- MOSTLY DRY THROUGH THIS WEEKEND
HIGH PRESSURE WILL DOMINATE OVER THE NEXT FEW DAYS. A SHORTWAVE
TROUGH MOVING THROUGH SATURDAY MAY SPARK OFF SOME POP-UP SHOWERS
AND THUNDERSTORMS LATE SATURDAY AFTERNOON AND EVENING. AT THIS
TIME IT IS A 20 PERCENT CHANCE WHERE MOST IF NOT ALL COULD REMAIN
DRY. HOWEVER WITH MEAN MUCAPE VALUES AROUND 1000 J/KG AND SOME
MOISTURE PRESENT AT 850 MB, DO NOT WANT TO RULE OUT SEEING AN
ISOLATED THUNDERSTORM.
- RAIN AND THUNDERSTORMS POSSIBLE MONDAY THOUGH THURSDAY
AN UPPER LEVEL RIDGE MOVES IN FOR MONDAY WITH SOUTHWEST FLOW
TOWARD THE SURFACE. THESE SOUTHWEST WINDS WILL BRING WARM AIR
ADVECTION ALONG WITH MOISTURE ADVECTION. SOME SHOWERS COULD
DEVELOP EARLIER IN THE DAY, OTHERWISE BETTER CHANCES (50 PERCENT
OR GREATER) MOVE IN MONDAY NIGHT INTO TUESDAY. MEAN MUCAPE VALUES
WILL BE AROUND 500 TO 1000 J/KG WITH SHEAR VALUES AROUND 35 KNOTS
THANKS TO A HEALTHY LOW LEVEL JET. THE TIMING ISN'T IDEAL FOR
SEVERE WEATHER, BUT A PERIOD TO KEEP AN EYE ON AS WE GET CLOSER.
SHOWERS COULD LINGER INTO WEDNESDAY AND THURSDAY AS WE REMAIN IN
SOUTHWEST FLOW UNTIL THE COLD FRONT MOVES THROUGH AND HIGH
PRESSURE MOVES IN.
HIGH TEMPERATURES WILL BE IN THE 70S WITH THE CHANCE FOR SOME TO
SEE LOW 80S ON TUESDAY. LOWS OVERNIGHT ARE EXPECTED TO BE IN THE
40S AND 50S. TEMPERATURES WILL BE A LITTLE WARMER IN THE 50S AND
60S EARLY TUESDAY MORNING.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 750 PM EDT THU SEP 10 2026
VFR CONDITIONS WILL DOMINATE THE PATTERN THROUGH MOST OF THE PERIOD.
WHILE WESTERLY TO NORTHWESTERLY WINDS WILL CONTINUE THERE IS
WEAKER FLOW THROUGH CENTRAL MICHIGAN. LATEST TRENDS CONTINUE TO
SHOW LIGHT WINDS OVERNIGHT AT LAN AND JXN. COUPLE THAT WITH COOLER
OVERNIGHT LOWS AND EXPECT ANOTHER ROUND OF MVFR TO IFR VSBYS.
IFR IS MOST LIKELY AT JXN. BEST TIME FOR REDUCING VSBYS IS
BETWEEN 09Z TO 15Z FRIDAY MORNING.
MARINE
ISSUED AT 219 PM EDT THU SEP 10 2026
NORTHWEST WINDS AROUND 5 TO 15 KNOTS ARE EXPECTED FOR THE REST OF
TODAY WITH WAVES HEIGHTS 2 FEET OR LESS. HIGH PRESSURE MOVES IN
FOR FRIDAY WITH OFFSHORE WINDS FRIDAY MORNING BECOMING MORE
ONSHORE DURING THE AFTERNOON. SOUTHWEST WINDS PICK UP SATURDAY
AHEAD OF A FRONT THAT WILL MOVE THROUGH LATE SATURDAY AFTERNOON
INTO THE EVENING. WINDS AND WAVES MAY APPROACH SMALL CRAFT
ADVISORY AND BEACH HAZARD STATEMENT LEVELS. POP-UP THUNDERSTORMS
AND SHOWERS WILL ALSO BE POSSIBLE WITH THE FRONT AS IT MOVES
THROUGH.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...RAH
AVIATION...CERU
MARINE...RAH
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