592
FXUS63 KGRR 122304
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
704 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 /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 704 PM EDT FRI SEP 12 2025
VFR CONDITIONS EXPECTED OVER THE NEXT 24 HOURS WITH A FEW CUMULUS
AND CIRRUS CLOUDS TONIGHT TRANSITIONING TO A CLOUD DECK AROUND
10KFT WITH INCREASED CLOUD COVER SATURDAY. ISOLATED SHOWERS ARE
POSSIBLE NEAR LAKE MICHIGAN AFTER 12Z, WITH PROB30 GROUPS ADDED AT
MKG AND GRR WHERE CHANCES ARE THE BEST. CONFIDENCE IS LOWER
INLAND (10-20%) PRECLUDING INCLUSION OF ANY SHOWERS IN THE TAFS AT
THIS TIME. AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT IF ENOUGH
INSTABILITY CAN DEVELOP. ANY SHOWERS THAT DO DEVELOP WOULD 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...THOMAS
MARINE...RAH
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