034
FXUS63 KGRR 092346
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
746 PM EDT MON JUN 9 2025
KEY MESSAGES
- ROUND OF THUNDERSTORMS THIS AFTERNOON AND EVENING
- ADDITIONAL THUNDERSTORM CHANCES LATE WEEK
DISCUSSION
ISSUED AT 253 PM EDT MON JUN 9 2025
- ROUND OF THUNDERSTORMS THIS AFTERNOON AND EVENING
AS DAYTIME INSTABILITY HAS INCREASE TO AROUND 500-1000 J/KG THIS
AFTERNOON WE ARE ALREADY SEEING SHOWERS AND STORMS DEVELOP AHEAD
OF THE MAIN LINE CURRENTLY MOVING ACROSS LAKE MICHIGAN. WE WILL
ALSO SEE A CORE OF SLIGHTLY STRONGER 850MB WINDS 30-35 KNOTS MOVE
IN WITH THE LINE. SOUNDING PROFILES HAVE AN INVERTED V LOOK TO
THEM SIGNIFYING HIGHER CLOUD BASES AND DRIER AIR AT THE SURFACE.
WITH THE SYNOPTIC LIFT MOVING IN WITH THE UPPER LEVEL LOW, MODEST
SHEAR, INSTABILITY, AND DRY AIR AT THE SURFACE SOME STRONG TO
SEVERE STORMS ARE POSSIBLE WITH WINDS BEING THE PRIMARY THREAT AND
HAIL AS THE SECONDARY.
ONCE THE LINE OF STORMS OVER LAKE MICHIGAN MOVES THROUGH, DRY
CONDITIONS ARE LARGELY EXPECTED OVERNIGHT. SOME SHOWERS MAY LINGER
TOWARD US-10 OVERNIGHT.
- ADDITIONAL THUNDERSTORM CHANCES LATE WEEK
WE REMAIN IN THE NORTHWEST FLOW WITH A COUPLE WEAK SHORTWAVE
TROUGHS MOVING THROUGH TUESDAY/TUESDAY NIGHT AND THEN AGAIN
WEDNESDAY NIGHT INTO THURSDAY. THE LOW LEVEL JET NOSES IN TUESDAY
NIGHT, BUT MOISTURE IS LACKING. BETTER MOISTURE IS PRESENT
WEDNESDAY NIGHT INTO THURSDAY WITH SHOWERS AND STORMS EXPECTED TO
CONTINUE OFF AN ON THROUGH THE REMAINDER OF THE WEEK AS A BOUNDARY
STALLS OVER THE AREA. THIS MATCHES UP WITH THE NBM POPS OF 30 TO
50 PERCENT.
TEMPERATURES DURING THIS TIME WILL BE IN THE 70S TO LOW 80S WITH
LOWS IN THE 50S. FRIDAY LOOKS TO BE THE COOLEST DAY OF THE WEEK
WITH AREAS NORTH OF I-96 POTENTIALLY REMAINING IN THE 60S.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 746 PM EDT MON JUN 9 2025
GENERALLY HIGH CONFIDENCE FOR TERMINALS TO REMAIN ABOVE IFR
THRESHOLDS OVERNIGHT NOW THAT THUNDERSTORMS HAVE EXITED THE AREA
AND BECAUSE WE EXPECT AT LEAST SOME WIND TO PERSIST OVERNIGHT. WE
ARE SEEING A TRAILING DECK OF HIGH MVFR CEILINGS (GENERALLY ABOVE
4000 FT AGL) THAT MAY IMPACT THE JXN, LAN, AND POSSIBLY BTL
TERMINALS MAINLY BEFORE 02Z.
WINDS DO REMAIN QUITE BRISK AT SOME LOCATIONS (INCLUDING GRR) AT
THE TIME OF THIS WRITING, BUT WE EXPECT WIND SPEEDS TO DECREASE
SUBSTANTIALLY AS WE APPROACH SUNSET AND ASSOCIATED STABILIZATION
OF THE BOUNDARY LAYER TAKES PLACE.
RAINFALL WAS SCANT IN COVERAGE OVERALL, BUT THE BTL TERMINAL DID
GET SOME DECENT ACCUMULATIONS SO THERE IS A NON-ZERO CHANCE FOR
MVFR VISIBILITY RESTRICTIONS IN FOG THERE, MAYBE EVEN BRIEF IFR,
IF WINDS MANAGE TO DECOUPLE.
MARINE
ISSUED AT 253 PM EDT MON JUN 9 2025
SCATTERED THUNDERSTORMS THIS AFTERNOON COULD BRING GUSTY WINDS AND
HAIL. ONCE STORMS PASS DRY CONDITIONS ARE EXPECTED UNTIL
WEDNESDAY NIGHT. WINDS MAY APPROACH SMALL CRAFT ADVISORY RIGHT
ALONG THE SHORELINE THIS AFTERNOON, BUT THE COLDER WATER
TEMPERATURES SHOULD KEEP MOST OF THESE GUSTS AT BAY.
WINDS LOOK TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS AND IN TURN
WAVE HEIGHTS ARE EXPECTED TO BE AROUND 3 FEET OR LESS THROUGH THE
REMAINDER OF THE WEEK.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...RAH
AVIATION...TJT
MARINE...RAH
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