533
FXUS63 KGRR 010608
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
208 AM EDT WED JUL 1 2026
KEY MESSAGES
- EXTREME HEAT THROUGH AT LEAST THURSDAY
- CHANCES FOR STORMS NEXT SEVERAL DAYS
DISCUSSION
ISSUED AT 320 PM EDT TUE JUN 30 2026
- EXTREME HEAT THROUGH AT LEAST THURSDAY
GUIDANCE CONTINUES TO FAVOR HIGHS IN THE LOWER TO MID 90S AND
HEAT INDEXES AROUND 100 TO 110 IN MOST LOCATIONS THROUGH THURSDAY.
OVERNIGHT LOWS IN THE MID 70S WILL PROVIDE LITTLE RELIEF TO THOSE
WITHOUT AIR CONDITIONING, ACCUMULATING HEAT STRESS ON THE BODY.
OVERNIGHT LOWS WEDNESDAY MORNING AND THURSDAY MORNING WILL
CHALLENGE DAILY RECORDS FOR WARMTH. ABOUT 50 PERCENT OF ECE
MEMBERS HAVE HIGHS ABOVE 90 ON FRIDAY. HIGH TEMPERATURES LATE IN
THE WEEK WILL DEPEND ON THE EXTENT AND TIMING OF THUNDERSTORMS,
THOUGH GENERALLY HIGHS IN THE 80S ARE FAVORED THROUGH THE HOLIDAY
WEEKEND.
- CHANCES FOR STORMS NEXT SEVERAL DAYS
A SUBSTANTIAL RESERVOIR OF CAPE WILL BE PRESENT IN THE REGION
THROUGH LATE IN THE WEEK, OFFERING POTENTIAL ENERGY FOR OCCASIONAL
THUNDERSTORMS AS MULTIPLE SHORTWAVES DEVELOP AND PROPAGATE
THROUGH THE WEST-SOUTHWESTERLY UPPER-LEVEL FLOW PATTERN EXTENDING
FROM THE SW CONUS TO THE GREAT LAKES. WITH TIME, AS THE UPPER
LEVEL RIDGE FLATTENS A LITTLE, THUNDERSTORMS WILL FAVOR SOUTHERN
MICHIGAN DURING THE LATTER HALF OF THE WEEK.
FOR WEDNESDAY, A THREAT OF SEVERE THUNDERSTORMS INCLUDES MAINLY
US-10 AND NORTH. THUNDERSTORMS DEVELOPING TODAY INTO TONIGHT FROM
KANSAS TO NEBRASKA MAY INDUCE A WAVE THAT COULD CONTINUE TOUCHING
OFF STORMS INTO WISCONSIN AND EVENTUALLY MICHIGAN BY MID DAY
WEDNESDAY, ESPECIALLY IF STORMS DEVELOPING A COLD POOL AND BECOME
FORWARD-PROPAGATING. IF THAT OCCURS, DCAPE WELL OVER 1000 J/KG
WOULD FAVOR SEVERE WIND GUSTS. AN ADDITIONAL THREAT OF STORMS
COULD OCCUR LATE WED NIGHT FROM A COMPLEX OF STORMS THAT DEVELOPS
LATE IN THE DAY OVER SOUTHERN MINNESOTA. CONFIDENCE IS RELATIVELY
LOW GIVEN WEAK LIFTING MECHANISMS AND A WIDE VARIETY OF MODEL
SOLUTIONS.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 208 AM EDT WED JUL 1 2026
BROAD SOUTHWEST FLOW WILL CONTINUE ACROSS SOUTHWEST LOWER MICHIGAN
THE NEXT 24 HOURS, WHICH WILL LIKELY KEEP THE TAF SITES VFR. A
STATIONARY FRONT WILL REMAIN UPSTREAM OVER MN, WI AND THE U.P.
DURING THE TAF PERIOD WHICH SHOULD KEEP MUCH OF THE THUNDERSTORM
ACTIVITY NORTH AND WEST OF THE TAF SITES. SMALL CHANCES THAT SOME
OF THIS ACTIVITY COULD WORK INTO THE MKG, GRR AND LAN THIS
AFTERNOON OR EVENING, BUT FEEL PROBABILITIES ARE TOO LOW TO
INCLUDE AT THIS TIME.
WE ARE LOOKING FOR SCATTERED TO POSSIBLY BROKEN CUMULUS
DEVELOPMENT AT TIMES IN THE 5,000 TO 6,000 FOOT RANGE OVER THE
NEXT 24 HOURS. LOW CEILINGS AND RESTRICTIONS TO VISIBILITY ARE NOT
ANTICIPATED. WINDS WILL BE SOUTHWEST AT 5 TO 10 KNOTS EARLY THIS
MORNING, INCREASING TO 10-20 KNOTS WITH GUSTS OF 20-25 KNOTS FROM
ROUGHLY 15Z THROUGH 01Z.
MARINE
ISSUED AT 200 PM EDT TUE JUN 30 2026
BEACH REPORTS, WEBCAMS, AND BUOYS INDICATE A MODERATE BORDERING
ON HIGH SWIM RISK ONGOING TODAY, WITH THE WAVE SPECTRUM GENERALLY
2 TO 4 FEET NEAR AND NORTH OF HOLLAND. SOUTH-SOUTHWEST WINDS OVER
THE LAKE AT ABOUT 15 KNOTS WILL INDUCE SOME LONGSHORE CURRENTS AND
STRUCTURAL CURRENTS PARTICULARLY AFFECTING SOUTH PIERS.
THE PORT SHELDON AND LUDINGTON BUOYS SIGNIFICANT WAVE HEIGHT
AROUND 2.5 FEET IS LESS THAN WHAT WE HAVE IN THE FORECAST, AS THE
NBM WINDS HAVE BEEN A LITTLE HIGH AND THE WINDS HAVE BEEN LESS W
EFFECTIVE AT IMPARTING MOMENTUM ONTO THE WATER IN THIS HIGHLY
STABLE MARINE AIR LAYER. MODELS INDICATE A SLIGHT UPTICK IN WINDS
POSSIBLE THIS AFTERNOON, SO WILL HOLD ON TO THIS LOW-END SMALL
CRAFT ADVISORY AND BEACH HAZARDS STATEMENT UNTIL ITS PLANNED
EXPIRATION AT 8 PM.
ANOTHER 2-4 FOOT WAVE AND MODERATE SWIM RISK DAY IS EXPECTED ON
WEDNESDAY. THUNDERSTORMS ON WEDNESDAY, IF THEY DEVELOP OVER
WISCONSIN AS INDICATED BY SOME MODELS, MAY CROSS CENTRAL LAKE
MICHIGAN AND COULD PRODUCE LOCALLY STRONG WIND GUSTS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...EXTREME HEAT WARNING UNTIL 8 PM EDT THURSDAY FOR MIZ037>040-
043>046-050>052-056>059-064>067-071>074.
MARINE...NONE.
DISCUSSION...CAS
AVIATION...DUKE
MARINE...CAS
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