747
FXUS63 KGRR 252216
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
616 PM EDT SAT APR 25 2026
KEY MESSAGES
- DRY UNTIL CHANCES FOR RAIN AND THUNDERSTORMS MONDAY NIGHT
- MAINLY DRY AND COOLER FOR THE REMAINDER OF NEXT WEEK
DISCUSSION
ISSUED AT 245 PM EDT SAT APR 25 2026
- DRY UNTIL CHANCES FOR RAIN AND THUNDERSTORMS MONDAY NIGHT
UPPER LEVEL RIDGING AND HIGH PRESSURE WILL REMAIN IN PLACE THROUGH
THE WEEKEND RESULTING IN DRY CONDITIONS. SOUTHWEST FLOW MOVES IN
MONDAY AHEAD OF THE SHORTWAVE TROUGH. UPPER LEVEL DIVERGENCE,
POSITIVE VORTICITY ADVECTION, AND THE LOW LEVEL JET LINE UP FOR
LATE MONDAY AFTERNOON INTO MONDAY NIGHT. THERE WILL BE PLENTY OF
SHEAR IN PLACE WITH THE 50 KNOT LOW LEVEL JET WITH WINDS UP TO 70
KNOTS IN THE MID LEVELS. THE QUESTION ON OUR SEVERE POTENTIAL WILL
LARGELY BE UP TO HOW MUCH INSTABILITY IS AVAILABLE. NBM MEAN
SBCAPE HAS INSTABILITY RANGING FROM A FEW HUNDRED TO A COUPLE
HUNDRED J/KG TOWARD US-10 TO NEAR 1000 J/KG TOWARD THE I-94
CORRIDOR. IF THESE INSTABILITY VALUES REMAIN THE SAME OR INCREASE,
THE SPC OUTLOOK WOULD LIKELY TREND UPWARD AS WE GET CLOSER. AFTER
THE INITIAL ROUND OF THUNDERSTORMS MONDAY NIGHT, SOME LINGERING
RAIN SHOWERS ARE POSSIBLE INTO TUESDAY MORNING.
- MAINLY DRY AND COOLER FOR THE REMAINDER OF NEXT WEEK
OVERALL WE'LL REMAIN UNDER THE UPPER LEVEL TROUGH WITH THE
POTENTIAL FOR A COUPLE SHORTWAVE TROUGHS TO MOVE THROUGH. THESE
TROUGHS COULD BRING SOME CHANCES (20 PERCENT) FOR LIGHT SHOWERS,
BUT MOISTURE IS LIMITED WITH PRECIPITABLE WATER VALUES REMAINING
LOW. HIGHS THROUGH THE WEEK ARE EXPECTED TO BE IN THE 50S WITH
LOWS IN THE 30S BRINGING THE RISK FOR A WIDESPREAD FROST.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 615 PM EDT SAT APR 25 2026
UPSTREAM SATELLITE AND OBSERVATIONS INDICATE DRIER AIR IS
BEGINNING TO ERODE THE ENTRENCHED MVFR CLOUD DECK ACROSS THE THUMB
REGION OF LOWER MICHIGAN. LAN AND JXN ARE THE TWO TERMINALS WHERE
MVFR CIGS PERSIST AS OF PRESENT, AND IT IS LIKELY IT WILL TAKE
UNTIL MID TO LATE EVENING FOR THOSE SITES TO SCATTER OUT. LATEST
SHORT RANGE MODEL GUIDANCE NOW SUGGESTS THAT THE DRIER AIR AND
SUBSIDENCE FROM A NEARBY HIGH PRESSURE SYSTEM WILL KEEP CLOUDS
SCATTERED OVERNIGHT. IT IS VERY POSSIBLE THAT POCKETS OF GREATER
CLOUD COVER MAY LEAD TO RESTRICTIONS AT TIMES, AS IF A BKN DECK
CAN BE ESTABLISHED MVFR CIGS ARE LIKELY WITH IFR AND LOWER
POSSIBLE. HOWEVER, CONFIDENCE IN WHERE AND WHEN THIS WOULD OCCUR
IS TO LOW TO INDICATE RESTRICTIONS AT THIS TIME. THE POTENTIAL FOR
RESTRICTIONS ENDS SUNDAY MORNING WHEN CONTINUED SUBSIDENCE AND
ARRIVAL OF DRY AIR CAUSES SKIES TO BECOME MOSTLY CLEAR THROUGH THE
END OF THE TAF WINDOW.
MARINE
ISSUED AT 245 PM EDT SAT APR 25 2026
WINDS ARE OVERACHIEVING THIS AFTERNOON AND WITH AN EXPECTED TREND
UPWARD, EXPECT GUSTS TO BE IN THE 25 TO 30 KNOT RANGE UNTIL THIS
EVENING. WITH THIS CHANGE HAVE ISSUED A SMALL CRAFT ADVISORY UNTIL
8PM. WINDS ARE EXPECTED TO WEAKEN AND TURN MORE EASTERLY TONIGHT
INTO SUNDAY WITH LOW WAVE HEIGHTS.
MONDAY WINDS TURN TO THE SOUTHWEST WITH A CHANCE FOR THUNDERSTORMS
TO MOVE IN DURING THE LATE AFTERNOON AND EVENING. SMALL CRAFT
ADVISORY CONDITIONS ARE LIKELY FOR MONDAY INTO TUESDAY. WINDS
SHOULD REMAIN BELOW GALES DUE TO THE COLD WATERS, HOWEVER STORMS
COULD BE STRONG TO SEVERE AND MIX DOWN STRONGER WINDS FROM ALOFT.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ844>849.
DISCUSSION...RAH
AVIATION...THOMAS
MARINE...RAH
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