368
FXUS63 KGRR 121115
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
715 AM EDT SAT JUL 12 2025
KEY MESSAGES
- SEVERE WEATHER CHANCES THIS AFTERNOON
- SHOWERS AND THUNDERSTORMS RETURN MID-WEEK
DISCUSSION
ISSUED AT 343 AM EDT SAT JUL 12 2025
- SEVERE WEATHER CHANCES THIS AFTERNOON
SHORTWAVE TROUGH AXIS GOES NEGATIVE TILT AS IT SWINGS THROUGH
TODAY WITH CONDITIONAL SEVERE THREAT ACROSS THE EASTERN ZONES THIS
AFTERNOON. MAIN THREAT WILL BE ISOLATED DOWNBURSTS WITH DEEP LAYER
SHEAR ONCE AGAIN A LIMITING FACTOR FOR PERSISTENT, ORGANIZED
CONVECTION, DESPITE 1500-2000 J/KG CAPE ACROSS THE AREA FROM LAN
TO JXN. SEVERE THREAT WINDS DOWN IN THE LATE AFTERNOON AND EARLY
EVENING AS STORMS SHIFT EAST.
- SHOWERS AND THUNDERSTORMS RETURN MID-WEEK
ZONAL FLOW WITH WEAK SFC RIDGING BRINGS FAIR WEATHER FOR SUNDAY
THROUGH TUESDAY THEN RAIN CHANCES RETURNS FOR MID-WEEK WITH THE
APPROACH OF A WEAK SHORTWAVE TROUGH. SHOWERS AND STORMS BECOME
MORE WIDESPREAD ON THURSDAY AS A COLD FRONT MOVES THROUGH. SEVERE
WEATHER THREAT ALSO INCREASES AS FORECAST DEEP LAYER SHEAR IS
PROGGED TO BE OVER 30 KNOTS ALONG WITH SUFFICIENT INSTABILITY FOR
ORGANIZED STORMS.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 115 AM EDT SAT JUL 12 2025
VFR CONDITIONS TO PREVAIL THIS MORNING THEN SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO FLARE UP SATURDAY AFTERNOON OVER
ROUGHLY THE EASTERN HALF OF LOWER MICHIGAN WITH SOME ISOLATED IFR
CONDITIONS IN HEAVY RAIN ALONG WITH WINDS GUSTING OVER 30 KNOTS
AND SMALL HALL IN STRONGER STORMS.
MARINE
ISSUED AT 343 AM EDT SAT JUL 12 2025
SCATTERED THUNDERSTORMS TODAY COULD BRING WIND GUSTS OVER 30
KNOTS OTHERWISE WINDS SHOULD BE BELOW 25 KNOTS THROUGH THE WEEKEND
AND INTO EARLY NEXT WEEK.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...OSTUNO
AVIATION...OSTUNO
MARINE...OSTUNO
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