177
FXUS63 KGRR 220059
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
859 PM EDT MON APR 21 2025
KEY MESSAGES
- WINDS DECREASING OVERNIGHT
- SEVERAL CHANCES FOR SHOWERS MID WEEK
- WARM AND WET FRIDAY INTO SATURDAY, DRY SUNDAY
UPDATE
ISSUED AT 859 PM EDT MON APR 21 2025
WIND GUSTS ARE LOWERING AND HAVE CANCELLED THE WIND ADVISORY A
BIT EARLY. THE GALE WARNING ON LAKE MICHIGAN HAS BEEN REPLACED
WITH A SMALL CRAFT ADVISORY ALTHOUGH IT LOOKS LIKE WINDS AND
WAVES WILL SUBSIDE BELOW ADVISORY LEVELS QUICKLY OVERNIGHT.
OTHERWISE DECREASING CLOUDS EXPECTED FROM WEST TO EAST OVERNIGHT
AS THE LOW PULLS AWAY AND SFC RIDGING ARRIVES. LOWS IN THE 30S.
DISCUSSION
ISSUED AT 309 PM EDT MON APR 21 2025
- WINDS DECREASING OVERNIGHT
WATER VAPOR IMAGES SHOW A SECONDARY UPPER PV MAX THAT HAS JUST
CROSSED THE MILWAUKEE AREA AND ENTERED SOUTHERN LAKE MICHIGAN. THIS
HAS BEEN ASSOCIATED WITH CONTINUED GUSTS IN EXCESS OF 35 KNOTS. SO,
IT DEFINITELY SEEMS PRUDENT TO KEEP THE WIND ADVISORY IN EFFECT AS
CURRENTLY SCHEDULED FOR NOW - ALTHOUGH IT CAN LIKELY BE CANCELLED
PRIOR TO THE SLATED 10 PM EXPIRATION TIME. WILL DEFER TO THE EVENING
SHIFT TO HAMMER OUT THESE DETAILS.
- SEVERAL CHANCES FOR SHOWERS MID TO LATE WEEK
SHORTWAVE RIDGING ALOFT WILL INTRODUCE ASSOCIATED SURFACE PRESSURE
RIDGING ACROSS THE WESTERN GREAT LAKES FOR MUCH OF TUESDAY. HOWEVER,
AS NOTED PREVIOUSLY WE ARE LOOKING AT A WARM FRONT LIFTING NORTH
TOWARDS LOWER MICHIGAN. THERE WILL BE A BAND OF STRONGER WESTERLY
FLOW ALOFT IN THE VICINITY, INDICATIVE OF MORE ISENTROPIC SLOPING
UNDERNEATH. WAVINESS IN THE MID-LEVEL FLOW WILL INDUCE ISENTROPIC
ASCENT WITHIN THIS SLOPED REGIME, LIKELY CULMINATING IN A BAND OF
SHOWERS AND PERHAPS EVEN STORMS AROUND OR SOUTH OF THE I-94 CORRIDOR
BEGINNING AS EARLY TUESDAY EVENING. GIVEN THE ELEVATED NATURE OF
PRECIPITATION AND EPHEMERAL ASPECTS OF THE FORCING, FORECAST
CERTAINTY WILL BE VERY LIMITED DURING THIS TIME FRAME.
- WARM AND WET FRIDAY INTO SATURDAY, DRY SUNDAY
THERE IS BETTER FORECAST CERTAINTY FOR SHOWERS AND THUNDERSTORMS TO
OVERSPREAD THE AREA DURING THIS TIME AS A WELL PHASED UPPER TROUGH
TRAVERSES THE AREA. UPPER MESOSCALE RIDGING AHEAD OF THE TROUGH
COMBINED WITH PLACEMENT IN THE WARM SECTOR MAY ALLOW HIGHS ON
THURSDAY TO MAKE A RUN TOWARDS 80 DEGREES ACROSS MUCH OF SOUTHWEST
LOWER MI.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 734 PM EDT MON APR 21 2025
CEILINGS ARE JUST ABOVE 3,000 FEET IN MOST PLACES, BUT STUBBORNLY
DIP AT OR BELOW 3,000 IN SPOTS. THIS SHOULD CONTINUE TO BE THE
CASE FOR THE NEXT SEVERAL HOURS, THEN DRIER AIR MOVING IN WILL
SCATTER OUT THE CLOUDS. VFR IS EXPECTED ON TUESDAY, WITH LIGHTER
WINDS. THERE MAY BE SOME RAIN SHOWERS MOVING INTO WEST MICHIGAN
DURING TUE AFTERNOON ALONG WITH SOME 5,000 TO 8,000 FT CEILINGS.
MARINE
ISSUED AT 309 PM EDT MON APR 21 2025
NO CHANGES TO THE GALE WARNING AT THIS TIME. THIS WILL EVENTUALLY
NEED TO BE REPLACED WITH A SMALL CRAFT ADVISORY SINCE WAVES WILL
MEET OR EXCEED THOSE CRITERIA MUCH OF TONIGHT.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR LMZ844>849.
UPDATE...DUKE
DISCUSSION...TJT
AVIATION...CAS
MARINE...TJT
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