347
FXUS63 KGRR 301736
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
136 PM EDT TUE JUN 30 2026
KEY MESSAGES
- EXTREME HEAT TODAY THROUGH AT LEAST THURSDAY
- CHANCES FOR STORMS LATER IN THE WEEK
DISCUSSION
ISSUED AT 308 AM EDT TUE JUN 30 2026
- EXTREME HEAT CONTINUES THROUGH AT LEAST THURSDAY
NO CHANGE FOR THE EXPECTATIONS OF TODAY BEING THE FIRST OF THREE
STRAIGHT DAYS WITH VERY DANGEROUS HEAT AND HUMIDITY. HIGHS IN THE
90S WITH LOWS IN THE UPPER 70S WILL BE COMMON TUESDAY THROUGH
THURSDAY WITH HEAT INDEX VALUES DURING THE DAY INTO THE 100S AND
IN THE NIGHTTIME PERIOD IN THE MID TO UPPER 80S. FRIDAY IS LIKELY
TO SEE SOME RELIEF AS THE UPPER RIDGE WEAKENS...THOUGH HIGHS
FRIDAY MAY ONLY BE ABOUT 5 DEGREES OR LESS COOLER THAN THE REST OF
THE WEEK. A LITTLE MORE RELIEF (THOUGH IT STILL WILL BE HOT)
COMES OVER THE HOLIDAY WEEKEND WHEN HIGH TEMPERATURES IN THE MID
80S WILL BE COMMON.
- CHANCES FOR STORMS LATER IN THE WEEK
STILL EXPECTING A SERIES OF SHORTWAVES TO TRY AND WEAKEN THE RIDGE
OVER US THE REST OF THE WEEK. SOME OF THESE WAVES COULD BRING
SHOWERS/THUNDERSTORMS TO SOUTHERN LOWER MICHIGAN. GENERALLY THE
GREATER SEVERE RISK WILL REMAIN OVER THE UPPER PENINSULA AND
NORTHERN LOWER...BUT INSTABILITY IS GOOD ENOUGH OVER SOUTHERN
LOWER TO KEEP A NON-ZERO SEVERE THREAT. HARD TO PICK WHICH DAYS OR
TIMEFRAMES ARE BEST FOR STORMS AND/OR ANY POSSIBLE SEVERE
WEATHER...THOUGH THE SEVERE RISK DOES CREEP A LITTLE FURTHER SOUTH
EACH DAY THROUGH THURSDAY.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 136 PM EDT TUE JUN 30 2026
AREAS OF MVFR CEILINGS AFFECTING SOME OF THE TERMINALS ARE EXPECTED
TO CHANGE INTO A SCATTERED LAYER ABOVE 3000 FT THIS AFTERNOON. IT
IS INTERESTING TO NOTE THAT MULTIPLE CLOUD LAYERS IN THE 2000-3000
FT RANGE HAVE BEEN REPORTED AT SOME OF THE TERMINALS HAVING
AUTOMATED ASOS OBSERVATIONS. THIS SUGGESTS THAT STRATOCUMULUS IS
INDEED BREAKING UP BECAUSE THIS PROCESS CAN OFTEN TRICK THE SMALL
DIAMETER, UPWARD POINTING CLOUD SENSORS AS WELL AS THE AVERAGING
ALGORITHMS ASSOCIATED WITH THE ASOS PLATFORMS.
OTHER THAN THAT, HAVE TRIED TO CAPTURE THE GUSTY NATURE OF WINDS
WITH GUSTS EXPECTED TO SUBSIDE AROUND OR SHORTLY AFTER 00Z.
MARINE
ISSUED AT 308 AM EDT TUE JUN 30 2026
SMALL CRAFT ADVISORY AND BEACH HAZARD STATEMENTS CONTINUE THROUGH
TODAY. GUSTY SOUTHWEST WINDS WILL DEVELOP BY EARLY AFTERNOON AND
WAVES SHOULD INCREASE FOR MOST THROUGH THE EVENING. GREATEST RISK
FOR SWIMMERS WILL BE SOUTH OF SOUTH PIERS WHERE EXTRA CAUTION
SHOULD BE TAKEN IN CHOPPIER CONDITIONS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR MIZ037-
043-050-056.
EXTREME HEAT WARNING UNTIL 8 PM EDT THURSDAY FOR MIZ037>040-
043>046-050>052-056>059-064>067-071>074.
AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR MIZ050-056-057-
064-071.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ846>849.
DISCUSSION...TJT
AVIATION...MACZKO
MARINE...MACZKO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page