259
FXUS63 KGRR 172337
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
737 PM EDT SAT MAY 17 2025
KEY MESSAGES
- DRY SUN/MON, THEN SHOWERS, CONTINUED COOL
DISCUSSION
ISSUED AT 214 PM EDT SAT MAY 17 2025
- DRY SUN/MON, THEN SHOWERS, CONTINUED COOL
UPPER LOW PRESSURE HAS BROUGHT AN ABRUPT CHANGE TO OUR WEATHER.
GONE ARE TEMPERATURES IN THE 80S, REPLACED BY HIGHS IN THE LOWER
TO MID 50S. COOLER TEMPERATURES...5 TO 10 DEGREES BELOW
NORMAL...WILL CONTINUE THROUGH THE WEEK.
A STRONG SHORT WAVE ROTATING AROUND THE UPPER LOW WILL MOVE EAST
LATER THIS AFTERNOON AND TAKE THE SHOWERS WITH IT. CLOUDS WILL
REMAIN THOUGH AS THE LONG WAVE UPPER TROUGH REMAINS OVER THE
GREAT LAKES. HREF MEAN CLOUD COVER PROG SHOWS THE LOWER CLOUDS
CONTINUING THROUGH TONIGHT AND SUNDAY MORNING BEFORE BEGINNING TO
LIFT OUT SUNDAY AFTERNOON. CONSSHORT PROGS SHOW THE SAME THING, SO
CONFIDENCE IS HIGH THAT TONIGHT AND SUNDAY MORNING WILL BE ON THE
CLOUDY SIDE.
AS SKIES CLEAR LATER SUNDAY, WE MAY BE LOOKING AT FROST POTENTIAL
ALONG THE US-10 CORRIDOR SUNDAY NIGHT WHERE TEMPERATURES ARE PROGD
TO FALL INTO THE MID 30S. THAT COULD BE A SIMILAR SITUATION
MONDAY NIGHT TOO, DEPENDING ON THE EASTWARD MOVEMENT OF A PLAINS
LOW. IF HIGH CLOUDS REMAIN TO THE WEST, THEN FROST WILL BE IN PLAY
MONDAY NIGHT.
THE PLAINS LOW WILL MOVE EAST TUESDAY AND WE COULD SEE SOME RAIN
SPREAD INTO THE SOUTHERN CWA LATE IN THE DAY, BUT MORE SO TUESDAY
NIGHT. THIS RAINY PATTERN WILL CONTINUE THROUGH MID WEEK AS THE
LOW MOVES ACROSS CENTRAL IL/IN. WE'LL BE ON THE NORTHERN SIDE OF
THE LOW WHICH MEANS A STEADY FEED OF COOLER AIR FROM THE EAST.
THIS DOESN'T LOOK LIKE MUCH OF A CONVECTIVE PATTERN UNLESS THE LOW
TAKES A TURN TO THE NORTH AND WE GET INTO THE WARM SECTOR.
TUESDAY THROUGH THURSDAY LOOK WET WITH DRIER CONDITIONS POSSIBLE
BY LATE WEEK, THOUGH THAT'S NOT CERTAIN. THE ECMWF SHOWS A COUPLE
OF SHORT WAVES PINWHEELING AROUND THE GREAT LAKES THURSDAY
THROUGH SATURDAY, KEEPING UNSETTLED CONDITIONS OVER THE CWA. MOST
OF THE ECMWF ENSEMBLE MEMBERS ALSO SHOW LIGHT QPF LATE WEEK.
HIGHS IN THE MID 60S SUNDAY AND MONDAY WILL BE FOLLOWED BY UPPER
50S TUESDAY THROUGH THURSDAY.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 737 PM EDT SAT MAY 17 2025
IFR CONDITIONS THROUGH 06Z SEEM UNLIKELY ESPECIALLY AS PRECIPITATION
CONTINUES TO DIMINISH IN COVERAGE ACROSS SOUTHWEST LOWER MICHIGAN.
WIND GUSTS ACROSS THE AREA ARE EXPECTED TO SUBSIDE BY AROUND 02Z.
AFTER 06Z, LATEST MODEL MODEL GUIDANCE AND UPSTREAM TRENDS SUGGEST
MVFR CEILING RESTRICTIONS CAN BE EXPECTED WITH A GRADUAL DESCENT
TO FUEL ALTERNATE CEILINGS (THAT IS, BELOW 2000 FEET AGL) AROUND
OR AFTER 09Z. THIS LOOKS MOST LIKELY TO OCCUR FOR THE TERMINALS
ACROSS INTERIOR LOWER MI, INCLUDING GRR, LAN, AND JXN. THERE IS A
LOW CHANCE OF BRIEF IFR CEILINGS (BELOW 1000 FEET) AFTER 10Z AT
SOME OF THESE LOCATIONS AS WELL BUT PROBABILITIES ARE TOO SMALL
TO EXPLICITLY MENTION IN THE TAFS AT THIS TIME.
CEILINGS COULD BE QUITE PERSISTENT FOR MUCH OF SUNDAY BUT MODELS
DO SUGGEST A GRADUAL WEST TO EAST EROSION MOVING INTO SUNDAY
AFTERNOON.
MARINE
ISSUED AT 214 PM EDT SAT MAY 17 2025
THREE TO FOUR FOOT WAVES ARE ONGOING IN THE NEARSHORE DUE TO THE
COOLER AIR AND THE GUSTY WINDS. THE SMALL CRAFT ADVISORY STILL
LOOKS GOOD AND WILL RUN THROUGH 2 AM. WIND AND WAVES WON'T POSE A
THREAT TO BOATERS SUNDAY AND MONDAY. ANOTHER SMALL CRAFT ADVISORY
MAY BE NEEDED TUESDAY AS LOW PRESSURE APPROACHES AND GUSTY EAST
WINDS DEVELOP.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR LMZ844>849.
DISCUSSION...04
AVIATION...TJT
MARINE...04
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