592
FXUS63 KGRR 301743
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
143 PM EDT MON JUN 30 2025
KEY MESSAGES
- FAIRLY HIGH CONCENTRATION OF SHOWERS AND STORMS THIS AFTERNOON
- MAINLY DRY THE REST OF THE WORK WEEK
- CHANCES FOR SHOWERS AND STORMS NEXT WEEKEND
DISCUSSION
ISSUED AT 348 AM EDT MON JUN 30 2025
- FAIRLY HIGH CONCENTRATION OF SHOWERS AND STORMS THIS AFTERNOON
SHOWERS AND STORMS HAVE DISSIPATED OVER LAKE MICHIGAN THIS MORNING
WITH THE BULK OF THE AREA SEEING DRY CONDITIONS AS OF 330AM. WE DO
NOT EXPECT MUCH OF AN UPTICK IN ACTIVITY EARLY THIS MORNING, BUT
WE CANNOT RULE OUT SOME SCATTERED SHOWERS AND STORMS OVER WESTERN
LOWER MICHIGAN AND LAKE MICHIGAN. THE SREF GUIDANCE DOES INDICATE
AT LEAST SOME ACTIVITY WILL REDEVELOP.
THE HREF 4 HOUR MAX REFLECTIVITY HAS BEEN CONSISTENT FROM RUN TO
RUN AND WE WILL THEREFORE NOT WAIVER IN OUR FORECAST OF SHOWERS
AND STORMS DEVELOPING IN THE LATE MORNING AND BECOMING NUMEROUS
THIS AFTERNOON. WE EXPECT SHOWERS AND STORMS TO DEVELOP ON A LAKE
BREEZE BOUNDARY THAT WILL EXTEND FROM SOUTHWEST TO NORTHEAST
ACROSS THE AREA FROM SOUTH HAVEN TO BIG RAPIDS. THE STORMS SHOULD
GO UP BETWEEN 11AM AND NOON AND THEN FILL IN/INCREASE IN COVERAGE
AS THEY MOVE EAST. HIGHEST CHANCES FOR SHOWERS AND STORMS TODAY
WILL BE FROM HIGHWAY 131 TO THE EAST.
WE WILL SEE SOLID INSTABILITY TODAY WITH MUCAPE VALUES BETWEEN
1500-2500 J/KG. WIND FIELDS ARE MID SUMMER LIKE, SPECIFICALLY
WEAK. THERE IS NO LOW LEVEL JET TO SPEAK OF WITH WINDS OF 15
KNOTS. THE MID LEVEL JET IS ALSO WEAK AROUND 25 KNOTS. DEEP LAYER
SHEAR IS ON THE ORDER OF 20 KNOTS. WE EXPECT A WIDE COVERAGE OF
STORMS THIS AFTERNOON THAT WILL LARGELY BE SUB SEVERE GIVEN THE
WEAKER WIND FIELDS. THAT SAID WE ARE IN A SPC MARGINAL RISK WHICH
IS DUE TO THE FACT THAT SOME WET MICROBURSTS WILL BE POSSIBLE.
STORMS WILL BE PULSE TYPE AND MULTICELLULAR AT TIMES. THE THREAT
TODAY WILL BE FROM CRASHING CORES THAT WILL BE FORCED VIA THE COLD
FRONT MOVING INTO AN UNSTABLE AIR MASS DRIVEN BY AN UPPER LEVEL
SHORTWAVE TROUGH. SO, WHILE WE ARE NOT EXPECTING WIDESPREAD SEVERE
STORMS DUE TO WEAK WIND FIELDS A FEW PULSE SEVERE WET MICROBURSTS
CANNOT BE RULED OUT.
- MAINLY DRY THE REST OF THE WORK WEEK
THE REST OF THE WORK WEEK AFTER TODAY SHOULD BE DRY. SURFACE
RIDGING SHOULD BE IN PLACE THE BULK OF THE TIME. WE WILL SEE A
SLOW WARMING TREND THROUGH THE WEEK AFTER NEAR NORMAL HIGHS ON
TUESDAY IN THE LOWER 80S. BY FRIDAY INTO SATURDAY 850MB
TEMPERATURES SURGE ONCE AGAIN TO AROUND +20C. SO, SOME 90S WILL BE
POSSIBLE AGAIN FRIDAY AND SATURDAY.
- CHANCES FOR SHOWERS AND STORMS NEXT WEEKEND
MODELS SHOW A WEAKENING COLD FRONT MOVING THROUGH THE AREA ON
SATURDAY INTO SATURDAY NIGHT. OUR HIGHEST CHANCES FOR
PRECIPITATION WITH THIS FRONT COMES SATURDAY NIGHT WHEN WE HAVE 60
PCT CHANCES OVER MUCH OF THE AREA.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 143 PM EDT MON JUN 30 2025
BROKEN LINE OF THUNDERSTORMS AFFECTING LAN AND JXN UNTIL ROUGHLY
19Z HAS TEMPORARY IFR VISIBILITY WITH HEAVY RAIN ALONG WITH
MICROBURSTS AND SURFACE GUSTS 25 TO 30 KNOTS AS THE COMPLEX MOVES
EAST. SCATTERED SHOWERS WITH MODERATE DOWNPOURS ARE POPPING UP
BEHIND THE STORM COMPLEX IN THE VICINITY OF GRR, AZO, AND BTL. THE
CHANCES FOR RAIN SHOWERS DIMINISH AS THE AFTERNOON GOES ON WITH
SOME MVFR CEILINGS LINGERING, BECOMING VFR AFTER 00Z.
MARINE
ISSUED AT 348 AM EDT MON JUN 30 2025
CONDITIONS ON THE BIG LAKE ARE EXPECTED TO REMAIN BELOW ADVISORY
LEVELS FROM TODAY AND THROUGH TUESDAY. WINDS TODAY WILL BE
RELATIVELY LIGHT FROM THE SOUTHWEST AT 5 TO 15 KNOTS. TONIGHT A
COLD FRONT WILL MOVE EAST, BUT WINDS OVER THE LAKE AND BEHIND THE
FRONT ARE NOT EXPECTED TO BE STRONG. WE MAY BRIEFLY (3-6 HOURS) REACH
10 TO 20 KNOTS OUT OF THE NORTHWEST, BUT THEN WINDS TAPER OFF
AGAIN ON TUESDAY. SO, AREAS SOUTH OF HOLLAND MAY SEE SOME 2-4 FOOT
WAVES OBSERVED TOWARDS DAYBREAK ON TUESDAY. OTHERWISE CONDITIONS
LOOK FAIRLY BENIGN INTO MID WEEK WITH WEAKER WINDS AND WAVES 2
FEET OR LESS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...DUKE
AVIATION...CAS
MARINE...DUKE
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