603
FXUS63 KGRR 161128
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
728 AM EDT FRI MAY 16 2025
KEY MESSAGES
- ANOTHER ROUND OF THUNDERSTORMS FRIDAY EVENING THEN FAIR AND
COOLER INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 252 AM EDT FRI MAY 16 2025
SEVERE STORMS HAVE MOVED EAST AND THERE WILL BE A TEMPORARY LULL
IN THE WEATHER UNTIL A SECOND BATCH OF STORMS ARRIVES FRIDAY
EVENING, ASSOCIATED WITH A COLD FRONT TRAILING FROM THE SFC
CYCLONE TRACKING ACROSS THE MICHIGAN UP.
DOWNBURST WINDS WILL BE THE MAIN THREAT, GENERALLY BETWEEN 8 PM
AND 11 PM, WITH INSTABILITY WANING DURING THE EVENING BUT
IMPRESSIVE DEEP LAYER SHEAR GREATER THAN 50 KNOTS RESULTING IN
ORGANIZED CONVECTION, MOSTLY IN THE FORM OF BOWING LINE SEGMENTS,
BUT ENOUGH DIRECTIONAL SHEAR TO ALLOW FOR SOME ROTATING UPDRAFTS
AS WELL.
COOLER, SHOWERY WEATHER MOVES IN BEHIND THE FRONT FOR SATURDAY THEN
A CANADIAN ANTICYCLONE BUILDS IN WITH FAIR WEATHER INTO AT LEAST
EARLY NEXT WEEK. GOOD RADIATIONAL COOLING CONDITIONS SUNDAY AND
MONDAY NIGHTS COULD BRING SCATTERED FROST WITH LOWS IN THE 30S
ACROSS THE NORTHERN ZONES. RAIN CHANCES RETURN BY MID-WEEK
ALTHOUGH SOME MODEL GUIDANCE SUGGEST MOST OF THE PRECIP REMAINS
SOUTH OF LOWER MICHIGAN.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 728 AM EDT FRI MAY 16 2025
VFR CONDITIONS TODAY WITH SOUTHERLY WINDS GUSTING TO 20 KNOTS.
THUNDERSTORMS COULD BRING AREAS OF MVFR AND BRIEF IFR IN HEAVY
RAIN THIS EVENING. STRONG DOWNDRAFTS ARE POSSIBLE WITH GUSTS OVER
40 KNOTS. LLWS WILL INCREASE THIS AFTERNOON AND BECOME STRONG THIS
EVENING.
MARINE
ISSUED AT 252 AM EDT FRI MAY 16 2025
NO CHANGES TO THE SMALL CRAFT ADVISORY. WINDS AND WAVES WILL BE
HAZARDOUS TO SMALL CRAFT THROUGH SATURDAY EVENING AND WINDS TO 25
KNOTS COULD PERSIST INTO SUNDAY, THOUGH THE TREND WILL BE FOR
CONDITIONS TO IMPROVE AS HIGH PRESSURE BUILDS IN FROM THE NORTH
EARLY NEXT WEEK, WITH WINDS GOING OFF SHORE AND WAVES DECREASING.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 2 AM EDT SUNDAY
FOR LMZ844>849.
DISCUSSION...OSTUNO
AVIATION...OSTUNO
MARINE...OSTUNO
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