376
FXUS63 KGRR 160550
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
150 AM EDT SUN AUG 16 2026
KEY MESSAGES
- CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH SUNDAY
- DRIER AND LESS HUMID THROUGH EARLY PART OF WEEK
- ANOTHER FRONTAL SYSTEM COULD BRING SHOWERS AND STORMS MIDWEEK
DISCUSSION
ISSUED AT 144 PM EDT SAT AUG 15 2026
- CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH SUNDAY
LIGHT SHOWERS ARE ALL THAT IS CURRENTLY MOVING THROUGH THE REGION
AS QUASI STATIONARY FRONT CONTINUES TO KEEP A WEAKENING MCV SOUTH
OF MICHIGAN. THE STABLE AIR OVER SOUTHERN MICHIGAN SHOULD
CONTINUE TO STIFLE CONVECTION. AS A SFC LOW MOVES EASTWARD THIS
AFTERNOON AND EVENING IT COULD MOVE NORTH ENOUGH TO ALLOW FOR
SCATTERED SHOWERS AND ISOLATED STORMS ALONG THE I-94 CORRIDOR.
THE SHEAR AND CAPE REMAIN THROUGH IN AND OHIO SO THE THREAT OF
SEVERE FROM ANY STORMS TO FORMS CONTINUES TO DIMINISH. ANY SHOWERS
AND STORMS THAT FORM WILL BE AIDED BY THE HUMID AIR MASS AND
HEAVY RAINFALL WILL BE POSSIBLE.
A SHORT UPPER LEVEL WAVE AND A DEEPENING MID LEVEL TROUGH WILL
SWING A FRONTAL SYSTEM THROUGH THE AREA TOMORROW. THIS COULD ALLOW
FOR ANOTHER CHANCE FOR SHOWERS TOMORROW MORNING INTO EARLY
AFTERNOON. WHILE LAPSE RATES AREN'T GREAT AND THE FRONT IS COMING
AT THE WRONG TIME OF DAY FOR CONVECTION, THERE SHOULD BE
SUFFICIENT CAPE AND PWATS ARE UPWARDS OF 2 INCHES FROM LATEST
CAMS. SO ANY SHOWERS OR STORMS THAT DO FORM COULD HAVE PERIODS OF
HEAVY RAIN.
- DRIER AND LESS HUMID THROUGH EARLY PART OF WEEK
THE FRONT WILL MOVE THROUGH TOMORROW WITH COOLER AND DRIER AIR IN
ITS WAKE WHICH WILL DROP TEMPS AND DEWPOINTS DOWN TO NORMAL
MAKING THE ARE MORE COMFORTABLE. MAX TEMPERATURES WILL BE NEAR
NORMAL, IN THE LOW 80S, THROUGH TUESDAY.
- ANOTHER FRONTAL SYSTEM COULD BRING SHOWERS AND STORMS MIDWEEK
THE QUASI STATIONARY HIGH THAT WAS SITTING OVER THE SOUTH AND
ALLOWED FOR ALL THE WEATHER TO MOVE THROUGH ILLINOIS AND INDIANA
THIS PAST WEEK WILL SHIFT TO THE WEST. THIS UPCOMING WEEK WILL BE
DOMINATED BY A LARGE UPPER LEVEL LOW THAT WILL BUILD OVER THE
HUDSON BAY. A IT TREKS TO THE EAST WILL SHOULD MOVE SOUTH OVER
NORTHERN ONTARIO AND A COLD FRONT EXTENDING FROM IT SHOULD MOVE
FROM THE NORTHWEST, ACROSS MICHIGAN AND SWEEP INTO THE MID
ATLANTIC BY THURSDAY. THERE IS SOME QUESTION ON TIMING BUT
CURRENTLY, THERE IS THE POTENTIAL FOR SHOWERS AND STORMS TUESDAY
NIGHT INTO WEDNESDAY. THIS SHOULD ALSO CLEAR TEMPERATURES OFF FOR
THE LATTER HALF OF THIS UPCOMING WEEK.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 150 AM EDT SUN AUG 16 2026
A MIX OF FLIGHT CATEGORIES ONGOING, AND OVERALL A DETERIORATION IN
CONDITIONS IS EXPECTED THIS MORNING. AN INCREASING NUMBER OF
AERODROMES SHOULD DIP TO IFR CEILINGS, THEN CLIMB BACK INTO MVFR
BETWEEN 13 AND 18 Z. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
ARE POSSIBLE THROUGH AT LEAST EARLY/MID AFTERNOON, WHETHER TOUCHED
OFF BY THE MCV TRACKING FROM NORTHERN ILLINOIS INTO SOUTHERN
MICHIGAN THIS MORNING, OR THE COLD FRONT SWEEPING THROUGH THE
STATE TODAY. CLOUDS SHOULD SCATTER OUT AND CLIMB ABOVE 3,000 FEET
BY LATE IN THE DAY.
MARINE
ISSUED AT 149 PM EDT SAT AUG 15 2026
OFFSHORE FLOW WILL CONTINUE THROUGH TODAY AND INTO TOMORROW WHICH
WILL KEEP WINDS AND WAVES LOW IN THE NEARSHORE. LARGER WAVES WILL
BUILD AS THEY MOVE WESTWARD IN THE OPEN WATERS. SHOWERS ARE
STORMS ARE POSSIBLE EARLY SUNDAY AND A COLD FRONT WILL SHIFT WINDS
TO THE NORTH TOMORROW NIGHT, WITH BUILDING WAVES IN THE OPEN
WATERS WHILE WAVES SHOULD REMAIN BETWEEN 1 TO 3 FEET IN THE
NEARSHORE.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...CERU
AVIATION...CAS
MARINE...CERU
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