656
FXUS63 KGRR 041810
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
210 PM EDT FRI SEP 4 2026
KEY MESSAGES
- SHOWERS AND STORMS ONCE AGAIN TODAY WITH SEVERE POTENTIAL
- PERIOD OF DRY WEATHER THIS WEEKEND INTO EARLY NEXT WEEK
- LESS HUMID AIR THIS WEEKEND
DISCUSSION
ISSUED AT 350 AM EDT FRI SEP 4 2026
- SHOWERS AND STORMS ONCE AGAIN TODAY WITH SEVERE POTENTIAL
SHOWERS AND THUNDERSTORMS CONTINUE TO FILL IN TO OUR WEST OVER
LAKE MICHIGAN AND WISCONSIN. THIS CONVECTION IS OCCURRING ON THE
NOSE OF THE LOW LEVEL JET WHICH IS AIDING IN LOW LEVEL THETA-E
ADVECTION INTO THE STORMS. THE LOW LEVEL JET IS FORECAST, WHICH
WAS DISCUSSED IN YESTERDAY AFTERNOON'S AFD, TO FOLD OVER TO THE
EAST AND BE AIMED INTO SOUTHWEST LOWER MICHIGAN MUCH OF THE
MORNING. CONSISTENCY WITH THIS FEATURE HAS BEEN GOOD, WHICH IS
SOMETHING WE HAVE NOT SEEN OF LATE IN THE MODELS GIVEN SOMEWHAT
NEBULOUS FORCING WHICH IS COMMON IN THE LATE SUMMER. DEEP LAYER
SHEAR IS EXPECTED TO BE AROUND 40 KNOTS THIS MORNING WITH MUCAPE
VALUES IN THE 1,000 TO 2,000 J/KG RANGE. THE PARAMETER SPACE IS
ROBUST EVEN AT THIS EARLY HOUR WHICH IS EVIDENCED BY NEARLY 2 INCH
HAIL IN THE MIDDLE OF THE NIGHT TO THE WEST OF THE LAKE IN
WISCONSIN.
WE EXPECT ROUNDS OF STORMS TO MOVE THROUGH SOUTHWEST LOWER
MICHIGAN THIS MORNING BETWEEN 4AM AND NOON. THE INITIAL ACTIVITY
IS CROSSING THE LAKE NOW AND GIVEN THE SURGE OF LOW LEVEL MOISTURE
VIA THE LOW LEVEL JET SEVERE WEATHER IS POSSIBLE ANY TIME DURING
THAT WINDOW. ITS POSSIBLE SOME ACTIVITY MAY PERSIST SLIGHTLY PAST
MIDDAY IN OUR SOUTH AND EAST TOWARDS JXN AND LAN, BUT THE
AFTERNOON SHOULD TREND DRIER WITH TIME. WIND LOOKS TO BE THE MAIN
SEVERE THREAT WITH GUSTS TO 60+ MPH POSSIBLE. SEVERE HAIL CANNOT
BE RULED OUT EITHER.
HEAVY RAIN AND LOCALIZED FLOODING REMAIN POSSIBLE TODAY GIVEN
PWATS NEAR 2.00 INCHES AND THE THREAT OF TRAINING THUNDERSTORMS.
AMOUNTS OF 0.50 TO 1.00 INCHES OF RAIN WILL BE LIKELY, BUT SWATHS
OF 1.50 TO 3.00 INCHES ARE QUITE POSSIBLE AS WELL. SHORT TERM
FLOODING POTENTIAL WILL BE MONITORED THIS MORNING.
SOME REDEVELOPMENT OF SHOWERS AND STORMS IN THE FAR SOUTHWEST CWA
TOWARDS SOUTH HAVEN WILL BE POSSIBLE THIS EVENING.
- PERIOD OF DRY WEATHER THIS WEEKEND INTO EARLY NEXT WEEK
A PERIOD OF DRY WEATHER IS EXPECTED THIS WEEKEND INTO EARLY NEXT
WEEK AS RIDGING WILL BE IN CONTROL OF THE AREA WEATHER. HIGH
CONFIDENCE IN DRY WEATHER THIS PERIOD GIVEN CONSENSUS IN THE
ENSEMBLES OF BOTH THE GFS AND ECMWF.
- LESS HUMID AIR THIS WEEKEND
AFTER WHAT HAS BEEN A PERIOD OF VERY HUMID AIR IT WILL BE
NOTICEABLY LESS HUMID THIS WEEKEND. DEW POINTS ARE IN MIDDLE 60S
TO AROUND 70 THIS MORNING. DEW POINTS IN THE 50S THIS WEEKEND WILL
FEEL QUITE PLEASANT IN COMPARISON.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 210 PM EDT FRI SEP 4 2026
WITH THIS MORNING'S THUNDERSTORM COMPLEXES OUT OF THE PICTURE, THE
FLIGHT CATEGORIES ARE MOSTLY IMPROVING TO VFR, EXCEPT FOR MVFR
CEILINGS EXPECTED TO HANG ON AROUND MOUNT PLEASANT (MOP), AND
PERHAPS A PATCH OR TWO OF CLOUDS BETWEEN 500 AND 2,000 FEET
DEVELOPING OVER THE NEXT HOUR OR SO ELSEWHERE.
TONIGHT WILL LIKELY BRING WORSENING CEILINGS OR VISIBILITY
SPREADING SOUTHWEST INTO THE TAF SITES FROM THAT SAME MOUNT
PLEASANT CLOUD DECK, BECOMING IFR AT SOME POINT LATE TONIGHT
(AFTER APPROX 03 TO 06 Z) THEN IMPROVING TO MVFR AFTER 13 Z. ALSO,
LINGERING INSTABILITY AND MOISTURE/CLOUDS AT OR ABOVE 4,000 FEET
IN SOUTHWEST MICHIGAN MAY DEVELOP SCATTERED THUNDERSTORMS NEAR
MKG, AZO, AND BTL BETWEEN 01 AND 08 Z.
MARINE
ISSUED AT 350 AM EDT FRI SEP 4 2026
THE QUIET PERIOD (LOWER WAVES AND WINDS) CONTINUES ON THE BIG LAKE
TODAY AND INTO THE WEEKEND. OVERALL, THE PATTERN CONTINUES WITH A
SLACK GRADIENT TODAY WHICH TRANSITIONS INTO SURFACE HIGH PRESSURE
THIS WEEKEND. WINDS SHOULD FOR THE MOST PART BE IN THE 5 TO 15
KNOT RANGE. WINDS MAY BE SLIGHTLY STRONGER ON SATURDAY, BUT THE
FLOW WILL BE OFF SHORE. WAVES SHOULD BE 2 FEET OR LESS TODAY
THROUGH THE WEEKEND.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...DUKE
AVIATION...CAS
MARINE...DUKE
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