781
FXUS63 KGRR 101754
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
154 PM EDT TUE JUN 10 2025
KEY MESSAGES
- MAINLY DRY TODAY AND SOMEWHAT BREEZY
- NUMEROUS ROUNDS OF SHOWERS AND THUNDERSTORMS LATE WEEK
- POTENTIALLY WIDE RANGE IN TEMPERATURES THURSDAY INTO WEEKEND
DISCUSSION
ISSUED AT 325 AM EDT TUE JUN 10 2025
- MAINLY DRY TODAY AND SOMEWHAT BREEZY
COLD AIR ADVECTION ON THE BACK SIDE OF A DEPARTING UPPER LOW WILL
HELP DEVELOP DIURNAL CUMULUS ACROSS THE REGION AND PERHAPS AN
ISOLATED SHOWER NORTH OF I-96 TODAY. MOST AREAS SHOULD STAY DRY.
NEITHER NBM NOR HREF POPS WOULD REALLY JUSTIFY ANYTHING ABOVE A
10% CHANCE ACROSS THE REGION FOR A SHOWER, SO IF YOU GET WET
YOU'LL JUST BE UNLUCKY. WESTERLY WINDS WILL FRESHEN BY MIDDAY AND
10-20 MPH WITH SOME GUSTS OF 25 MPH ARE EXPECTED, BUT THAT'S
CERTAINLY LOWER THAN YESTERDAY.
AN ASSESSMENT OF THE 00Z HRRR SMOKE MODEL INDICATES VERTICALLY
INTEGRATED SMOKE VALUES MAY GET HIGH ENOUGH TO CAUSE A BIT OF A
HAZE IN THE SKY THIS AFTERNOON. THIS SHOULD STAY ALOFT WITH NO
REAL CONCERNS FOR NEAR SURFACE IMPACTS.
- NUMEROUS ROUNDS OF SHOWERS AND THUNDERSTORMS LATE WEEK
A COMPLICATED FORECAST EXISTS FROM AS EARLY AS WEDNESDAY NIGHT
INTO AT LEAST A PORTION OF THE WEEKEND. MID LEVEL ZONAL FLOW SETS
UP ACROSS THE GREAT LAKES WHILE HIGHER UP AT 250MB, THERE IS
POTENTIAL FOR A FAIRLY PROLONGED PERIOD OF SOME UPPER JET
DIVERGENCE FROM THE UPPER MIDWEST INTO THE GREAT LAKES. DESCENDING
LOWER IN THE ATMOSPHERE, MODEL GUIDANCE IS INDICATING A FAIRLY
SIGNIFICANT THERMAL GRADIENT SETTING UP AT 850MB RIGHT OVER THE
REGION ALONG WITH WHAT IS INCREASINGLY LOOKING LIKE EITHER A
STALLED FRONTAL BOUNDARY OR SLOWLY MEANDERING WARM FRONT DRAPED
FROM MN/WI INTO LOWER MI BEGINNING LATE WEDNESDAY NIGHT AND
POTENTIALLY LINGERING INTO THE EARLY PORTION OF THE WEEKEND. THIS
FRONTAL BOUNDARY WILL BEGIN ACTING AS A TRIGGER FOR SOME SHOWERS
AND THUNDERSTORMS TO DEVELOP.
THE ECMWF AND ITS ASSOCIATED ENSEMBLE SUITE HAS BEEN PLAYING OUT
THIS SCENARIO OVER THE LAST FEW RUNS, THOUGH SOME QUESTIONS EXIST
ABOUT HOW MUCH OF A LOW LEVEL JET INFLUENCE OUR REGION WILL GET AS
THE BETTER SETUP LOOKS TO OCCUR ACROSS MN AND WI LATE WEEK.
HOWEVER, THE ECMWF IS SUGGESTING A CURVATURE IN OUR DIRECTION OF
A WEAK LLJ OF 20-25 KTS AND MAYBE UP TO 30 KTS AT TIMES MOVING IN
WAVES OVER A 48 TO 72 HR PERIOD. DEW POINTS LOOK TO REACH THE 60S
SOUTH OF THE WARM FRONT STARTING WEDNESDAY NIGHT, AND PWAT VALUES
WILL SOLIDLY BE 1.50" OR HIGHER. MUCAPE VALUES MAY CLIMB TO 1000
J/KG OR MORE. AS A RESULT OF THESE FACTORS, THERE SHOULD BE AMPLE
MOISTURE AND INSTABILITY INTERACTING WITH THE STALLED BOUNDARY TO
FIRE OFF MULTIPLE ROUNDS OF SHOWERS AND STORMS. THE BOUNDARY MAY
LIFT A BIT NORTH ON FRIDAY AS A SOMEWHAT DEFINED SHORTWAVE IN THE
MIDLEVEL FLOW HELPS STRENGTHEN THE LOW LEVEL JET ACROSS THE
MIDWEST, BUT THAT ISN'T CERTAIN YET.
AS IT CURRENTLY STANDS, THE FRONT MAY BE POSITIONED TO LARGELY
PARK ITSELF OVER THE REGION FOR A PROLONGED PERIOD, LEADING TO
SOME DECENT RAINFALL. HERE IS A SAMPLING OF THE 00Z ECE RAINFALL
PROBABILITIES FROM THURSDAY THROUGH SATURDAY FOR LOCATIONS SUCH AS
MUSKEGON, GRAND RAPIDS, AND LANSING. CHANCE FOR 0.50" OR MORE:
BETWEEN 90% AND 100%. CHANCE FOR 1.00" OR MORE: BETWEEN 60% AND
80%. CHANCE FOR 2.00" OR MORE: BETWEEN 20% AND 40%. KEEP IN MIND
THIS ENSEMBLE SYSTEM IS NON-CONVECTIVE ALLOWING, SO IT CAN'T
RESOLVE THUNDERSTORMS. WE MAY SEE THESE RAIN AMOUNTS TREND HIGHER
ONCE THE SYSTEM ENTERS THE WINDOW FOR THE CONVECTIVE ALLOWING
MODELS TO ASSESS. OUR LARGELY DRY SOILS AND FAIRLY NORMAL RIVER
LEVELS SHOULD BE WELL POSITIONED TO HANDLE A DECENT AMOUNT OF
RAIN, BUT WITH A SYNOPTIC SETUP SUCH AS THIS ONE WE'LL HAVE TO
MONITOR TRENDS CAREFULLY.
- POTENTIALLY WIDE RANGE IN TEMPERATURES THURSDAY INTO WEEKEND
THE POSITION OF THIS FRONTAL BOUNDARY WILL MAKE ALL THE DIFFERENCE
IN HOW WARM WE GET EACH DAY FROM THURSDAY INTO AT LEAST SATURDAY.
ENSEMBLE SPREAD IN MAXIMUM TEMPERATURES IS SIGNIFICANT DUE TO THE
INABILITY YET TO PIN DOWN THE EXACT FRONTAL POSITION. NORTH OF THE
FRONT, MODEL GUIDANCE IS SHOWING COOL TEMPERATURES WITH HIGHS IN
THE 50S OR 60S, WHILE SOUTH OF THE FRONT 70S AND 80S WILL EXIST.
NBM TEMPERATURES WILL AVERAGE OUT THESE SCENARIOS WHILE IN REALITY
IT WILL LIKELY BE ONE OR THE OTHER, SO EXPECT SOME REFINEMENT IN
THE TEMPERATURE FORECAST YET TO COME.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 154 PM EDT TUE JUN 10 2025
A MID LEVEL DISTURBANCE IS WORKING FROM WEST TO EAST THROUGH THE
NORTHERN GREAT LAKES THIS AFTERNOON. THE MID LEVEL WAVE IS
PUSHING A SURFACE TROUGH THROUGH SOUTHWEST LOWER MICHIGAN THIS
AFTERNOON. NEAR AND BEHIND THE TROUGH (WHICH STRETCHES FROM CHEBOYGAN
TO CADILLAC TO FREMONT) THERE ARE PLENTY OF BOTH CUMULUS AND
STRATOCUMULUS WITH BASES RANGING FROM NEAR 2,000 FEET AT CADILLAC
TO 4,000 TO 5,000 FEET. WE ARE EXPECTING MAINLY VFR CEILINGS
ABOVE 3,500 FEET AT THE TAF SITES THIS AFTERNOON. AS WE MOVE
TOWARDS EVENING WE EXPECT ALL OF THE TAF SITES TO SCATTER OUT AND
CLEAR, BETWEEN 22Z AND 02Z.
CLEAR SKIES WILL PREVAIL OVERNIGHT WITH SOME ALTOCUMULUS SHOWING
UP TOWARDS DAYBREAK WITH BASES NEAR AND ABOVE 9,000 FEET. THESE
CONDITIONS WILL PERSIST THROUGH THE MORNING HOURS OF WEDNESDAY.
SOUTHWEST TO WEST WINDS THIS AFTERNOON OF 10 TO 20 KNOTS WILL
SUBSIDE QUICKLY THIS EVENING BECOMING LIGHT TONIGHT. WINDS RAMP UP
QUICKLY LATE TONIGHT AFTER 09Z WITH SOUTHWEST WINDS OF 15-30
KNOTS DEVELOPING. WINDS WILL PEAK AROUND 18Z ON WEDNESDAY WITH
GUSTS TOWARDS 30 KNOTS POSSIBLE.
MARINE
ISSUED AT 325 AM EDT TUE JUN 10 2025
THE NEXT HAZARDOUS PERIOD FOR MARINERS LOOKS TO OCCUR EARLY
MORNING WEDNESDAY INTO THE EARLY WEDNESDAY AFTERNOON PERIOD AS SW
WINDS INCREASE TO NEARLY 25 KNOTS. THIS MAY HELP GENERATE WAVES
HIGH ENOUGH TO REACH SCA CRITERIA.
GRR WATCHES/WARNINGS/ADVISORIES
MI...AIR QUALITY ALERT FROM MIDNIGHT TONIGHT TO MIDNIGHT EDT
WEDNESDAY NIGHT FOR MIZ050-056-057-064-071.
MARINE...NONE.
DISCUSSION...HOVING
AVIATION...DUKE
MARINE...HOVING
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