866
FXUS63 KGRR 121858
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
258 PM EDT FRI SEP 12 2025
KEY MESSAGES
- RAIN AND A FEW THUNDERSTORMS SATURDAY
- DRY WITH WARMER TEMPERATURES SUNDAY INTO NEXT WEEK
DISCUSSION
ISSUED AT 258 PM EDT FRI SEP 12 2025
- RAIN AND A FEW THUNDERSTORMS SATURDAY
AN AREA OF RAIN AND THUNDERSTORMS WILL BE RIDING THE RIDGE INTO
THE AREA SATURDAY MORNING AND AFTERNOON. ADDITIONAL SUPPORT FROM
A TROUGH AXIS FROM THE UPPER LEVEL LOW OVER NORTHER QUEBEC WILL
PROVIDE A CHANCE 20-30 PERCENT FOR THUNDERSTORMS TO EXPAND
FURTHER INLAND DURING THE MORNING AND AFTERNOON. THE ONE LIMITING
FACTOR IS INSTABILITY. HREF AND OTHER ENSEMBLE MEAN MUCAPE VALUES
ARE LIMITED WITH THE HIGHER VALUES FARTHER SOUTHWEST. OVERALL
VALUES AROUND 500 J/KG ARE EXPECTED MAINLY TOWARD THE LAKESHORE
AND DROP OFF TO THE EAST. THERE WILL BE DECENT SHEAR AROUND 35
KNOTS WITH THE EDGE OF A WEAKENING LOW LEVEL JET JUST TO THE WEST.
MESO MODELS ARE PICKING UP ON AN ORGANIZED CLUSTER OF STORMS
MOVING ACROSS THE LAKE DURING THE MORNING AND EARLY AFTERNOON
CLIPPING OUR LAKESHORE AREAS. SOME STRONGER GUSTS ARE POSSIBLE,
HENCE THE SPC MARGINAL OUTLOOK FOR PORTIONS OF SOUTHWEST MICHIGAN.
THE BETTER CHANCES FOR THESE STRONGER GUSTS WILL BE OVER LAKE
MICHIGAN AND INTO INDIANA AS STORMS MAY BECOME MORE SURFACE BASED.
IF STORMS TREND TO MOVE THROUGH LATER INTO THE AFTERNOON, THE
CHANCE FOR STRONGER GUSTS WOULD INCREASE OVER SOUTHWEST MICHIGAN.
DRY CONDITIONS MOVE IN BY THE EARLY EVENING BEHIND THE TROUGH
AXIS.
- DRY WITH WARMER TEMPERATURES SUNDAY INTO NEXT WEEK
INCREASING HEIGHTS AS THE RIDGE AXIS MOVES OVERHEAD WILL BRING A
STRETCH OF DRY AND WARM WEATHER THROUGH MOST OF NEXT WEEK. HIGHS
WARM INTO THE MID TO UPPER 80S WITH OVERNIGHT LOWS IN THE 50S.
WINDS OVERALL WILL BE LIGHT AND VARIABLE. THE RIDGE OF HIGH
PRESSURE LOOKS TO WEAKEN TOWARD THE END OF NEXT WEEK WHICH MAY
BRING US OUR NEXT CHANCE FOR RAIN.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 140 PM EDT FRI SEP 12 2025
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD WITH LIGHT AND
VARIABLE WINDS BECOMING MORE SOUTHWESTERLY SATURDAY MORNING. CLOUD
COVER WILL INCREASE OVERNIGHT INTO FRIDAY MORNING WITH CEILINGS
DROPPING TO AROUND 10000 FEET BY THE AFTERNOON. AN AREA OF SHOWERS
AND A FEW THUNDERSTORMS WILL BE POSSIBLE MAINLY FOR AREAS CLOSER
TO LAKE MICHIGAN AFTER 12Z TOMORROW. CONFIDENCE IS LOWER FURTHER
INLAND. IF SHOWERS DO OCCUR THEY LOOK TO CLEAR BY 00Z SUNDAY.
MARINE
ISSUED AT 258 PM EDT FRI SEP 12 2025
OVERALL LIGHT WINDS AND LOW WAVE HEIGHTS ARE EXPECTED THROUGH MOST
OF NEXT WEEK. THE ONLY CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE SATURDAY MORNING AND AFTERNOON. STORMS MAY PRODUCE STRONG
WINDS, WITH THE BEST CHANCE OVER THE OPEN WATERS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...RAH
AVIATION...RAH
MARINE...RAH
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