487
FXUS63 KGRR 252334
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
734 PM EDT SAT JUL 25 2026
KEY MESSAGES
- SEVERAL CHANCES FOR THUNDERSTORMS TONIGHT THROUGH MONDAY NIGHT
WITH SEVERE WEATHER POSSIBLE
- DRY AND COOLER MID TO LATE WEEK
DISCUSSION
ISSUED AT 151 PM EDT SAT JUL 25 2026
- SEVERAL CHANCES FOR THUNDERSTORMS TONIGHT THROUGH MONDAY NIGHT
WITH SEVERE WEATHER POSSIBLE
BOTTOM LINE UP FRONT. SEVERAL CHANCES FOR STRONG TO SEVERE
THUNDERSTORMS EXIST SUNDAY INTO MONDAY NIGHT. HOWEVER, CONFIDENCE IN
TIMING AND COVERAGE OF ANY STORMS REMAINS LOW.
FIRST OFF. A SHORTWAVE CROSSES THE AREA TONIGHT ALONG WITH PLACEMENT
OF LFQ JET FORCING. THIS WILL BRING POTENTIAL FOR SHOWERS AND MAYBE
ISOLATED NON-SEVERE STORMS. GIVEN THE DRY AMBIENT AIRMASS, COVERAGE
WILL BE POOR WITH MOST AREAS HAVING A 20% OR LESS CHANCE OF RAIN
TONIGHT.
ATTENTION THEN TURNS TO SUNDAY AFTERNOON AS MLCIN ERODES WITH THE
ARRIVAL OF A SHORTWAVE AND MESO-LOW DEVELOPMENT ACROSS INTERIOR MI.
BEST EROSION OF MLCIN WILL BE NEAR AND EAST OF US-127, HOWEVER
WITHOUT MUCH IN THE WAY OF MESOSCALE FORCING, COVERAGE IS
QUESTIONABLE. IN ADDITION, FORECAST PROFILES IN SOME SHORT RANGE
MODEL GUIDANCE SHOW A MID-LEVEL CAP WHICH WOULD INHIBIT STORM
DEVELOPMENT. HOWEVER, IF STORMS CAN DEVELOP, SHEAR AND INSTABILITY
IS SUFFICIENT FOR DAMAGING WINDS AND HAIL.
SOME SHORT RANGE GUIDANCE SHOWS THE POTENTIAL FOR ONE OR MORE STORM
CLUSTERS TO DEVELOP IN WARM AIR ADVECTION SUNDAY NIGHT/EARLY MONDAY.
IF/WHERE THIS HAPPENS IS LOW CONFIDENCE WHICH IS COMMON IN "RING OF
FIRE" SCENARIOS LIKE THIS. ANY STORMS WILL BE CAPABLE OF DAMAGING
WINDS AND LARGE HAIL.
THE GREATEST CONCERN FOR AN ORGANIZED SEVERE WEATHER THREAT IS
MONDAY AFTERNOON/EVENING AS A COLD FRONT MOVES THROUGH THE AREA.
WHAT OCCURS AS THIS HAPPENS IS DEPENDENT ON IF/TO WHAT EXTENT WE SEE
ANY MORNING STORMS WHICH WILL AFFECT OUR ABILITY TO DESTABILIZE.
HOWEVER, BOTH A STRONG MID-LEVEL JET (WITH ATTENDANT FORCING) AND AN
INCREASING LOW-LEVEL JET IN THE EVENING WILL PROVIDE AMPLE LOW-LEVEL
AND DEEP LAYER SHEAR THAT GIVEN SUFFICIENT INSTABILITY, SEVERE
WEATHER IS POSSIBLE WITH ANY CLUSTERS OR MCSS THAT DEVELOP. THE
FAVORED AREA FOR THIS AT PRESENT IS THE SOUTHERN 2/3 OF OUR FORECAST
AREA. DAMAGING WINDS WOULD BE THE MAIN THREAT WITH ALL HAZARDS
POSSIBLE.
THE CAVEAT AS ALLUDED TO EARLIER IS THIS IS A HIGHLY UNCERTAIN
SETUP. WHERE EXACTLY THESE CLUSTERS DEVELOP AND TRACK IS TOUGH TO
PREDICT MORE THAN 12-24 HOURS OUT. THERE ARE REAL CHANCES LIKE HAS
HAPPENED OTHER DAYS OVER THE LAST FEW WEEKS THAT STORMS FAIL TO
DEVELOP, OR THAT THEY MISS OUR AREA KEEPING US DRY. EACH SUBSEQUENT
ROUND OF STORMS ALSO DEPENDS ON WHAT HAPPENS WITH PREVIOUS STORMS
AND ANY POTENTIAL BOUNDARIES OR DEBRIS CLOUDS. HOWEVER, THE
ENVIRONMENT IS FAVORABLE FOR STORMS TO BE SEVERE IF THEY DEVELOP.
- DRY AND COOLER MID TO LATE WEEK
CONDITIONS DRY OUT GOING INTO TUESDAY AS THE COLD FRONT CLEARS THE
AREA. UPPER-LEVEL TROUGHING AND SURFACE RIDGING KEEPS US A BIT
COOLER AS WELL AS DRY INTO THURSDAY. PRECIPITATION CHANCES THEN
RETURN FRIDAY AS A SHORTWAVE SWINGS THROUGH THE AREA.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 730 PM EDT SAT JUL 25 2026
VFR WILL CONTINUE FOR MOST OF THE TAF PERIOD. HOWEVER, THERE ARE
CAVEATS. A WEAK TROUGH WILL MOVE THROUGH EARLY SUNDAY. WHILE SOME
MODELS HAVE PRECIP, THE LOW LEVELS SHOULD BE TO DRY. FOR THE
CHANCE OF PRECIP AT GRR HAVE PUT IN A PERIOD OF PROB30. THERE
IS ENOUGH MOISTURE FOR LOW CLOUDS BETWEEN 08Z TO AROUND 15Z. THIS
COULD BE ENOUGH FOR MVFR CIGS AT AZO, BTL, GRR AND MKG. THERE WILL
BE A BETTER CHANCE FOR SHOWERS AND STORMS AT THE TAIL END OF THE
TAF PERIOD AND OVERNIGHT INTO MONDAY.
MARINE
ISSUED AT 151 PM EDT SAT JUL 25 2026
WINDS CLIMBING TO 15-17 KTS THIS AFTERNOON WILL SUPPORT 2-4 FOOT
WAVES, HIGHEST NORTH OF GRAND HAVEN. WILL HAVE TO MONITOR WEBCAMS
AND OBSERVATIONS FOR A BRIEF BURST OF HIGHER WINDS TO SUPPORT WAVES
BUILDING TO 3-5 FT. BEST CHANCE FOR THIS TO OCCUR IS NEAR THE POINTS
IF IT DOES OCCUR. SOME MEDIUM RANGE GUIDANCE SUGGESTS A SIMILAR
SCENARIO IN SOUTHERLY FLOW MONDAY AFTERNOON AHEAD OF A COLD FRONT.
INCREASING NORTHERLY FLOW BEHIND A COLD FRONT TUESDAY THEN MAKES
SMALL CRAFT/BEACH HAZARDS WINDS AND WAVES LIKELY. IN ADDITION,
SEVERAL CHANCES FOR THUNDERSTORMS EXIST SUNDAY EVENING INTO MONDAY
NIGHT. LOCALLY HIGHER WINDS (POSSIBLY IN EXCESS OF 34 KTS)/WAVES ARE
POSSIBLE IN ANY THUNDERSTORMS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...THOMAS
AVIATION...CERU
MARINE...THOMAS
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