386
FXUS63 KGRR 190008
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
808 PM EDT SAT APR 18 2026
KEY MESSAGES
- COOL WEEKEND WITH FROST/FREEZE POTENTIAL TONIGHT AND SUNDAY
NIGHT
- DRY UNTIL LATE WEEK WITH WARMING TEMPS
DISCUSSION
ISSUED AT 221 PM EDT SAT APR 18 2026
- COOL WEEKEND WITH FROST/FREEZE POTENTIAL TONIGHT AND SUNDAY
NIGHT
WEST MICHIGAN CURRENTLY SITS IN A POST-FRONTAL COLD AIR ADVECTION
REGIME WITH TEMPERATURES FALLING COMPARED TO THIS MORNING. IN SHARP
CONTRAST TO RECENT WARMTH TEMPERATURES FALL TONIGHT AS WE GET AN
ADVECTIVE FREEZE EVENT. TEMPERATURES WITHIN THE MIXING LAYER
OVERNIGHT REACH -15C SUPPORTING TEMPS IN THE LOW TO MID 30S THROUGH
ADVECTIVE FREEZE PROCESSES INLAND OF THE MARINE LAYER. HAVE ISSUED A
FROST ADVISORY FOR ALL OF OUR COUNTIES WHERE THE GROWING SEASON IS
UNDERWAY. CLEAR SKIES ARE LIKELY EVEN WITH 850MB TEMPS APPROACHING
LES CLOUD DEVELOPMENT LEVELS GIVEN THAT THE CORE OF THE COLD AIR
ALOFT DOESN'T ARRIVE UNTIL NEAR DIURNAL MINIMUM.
A MORE CLASSIC FREEZE EVENT IS EXPECTED SUNDAY NIGHT AS SKIES CLEAR
OUT AND LIGHT WINDS ALLOW FOR SUBSTANTIAL RADIATIONAL COOLING, WITH
OVERNIGHT TEMPERATURES FALLING INTO THE 20S. DEPENDING ON
RADIATIONAL COOLING EFFICIENCY THERE IS THE POTENTIAL OF THIS BEING
A HARD FREEZE. GIVEN THE RECENT WARMTH LEADING TO GROWING SEASON
BEING WELL UNDERWAY ACROSS PARTS OF THE AREA AND HIGHER CONFIDENCE
IN A FREEZE SETUP, HAVE ISSUED A FREEZE WATCH FOR ALL AREAS WHERE
THE GROWING SEASON HAS BEGUN FOR SUNDAY NIGHT.
- DRY UNTIL LATE WEEK WITH WARMING TEMPS
LARGE SCALE RIDGING AND SUBSIDENCE WILL SUPPORT DRY CONDITIONS
CONTINUING THROUGH THE DAY ON THURSDAY BEFORE A MID-LEVEL SHORTWAVE
AND ASSOCIATED SURFACE LOW BRING SHOWER AND THUNDERSTORM CHANCES
BACK TO WEST MICHIGAN. 850MB TEMPS CLIMB BACK INTO THE TENS ABOVE
ZERO BY LATE WEEK WITH HIGHS IN THE 60S BY TUESDAY AND WELL IN THE
70S BY LATE WEEK.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 807 PM EDT SAT APR 18 2026
VFR WEATHER IS EXPECTED THE NEXT 24 HOURS. CEILINGS WILL RANGE
FROM 4,000 TO 6,000 FEET WITH PERIODS OF CLEARING AS WELL,
ESPECIALLY TONIGHT. WINDS WILL SLACKEN A BIT TONIGHT DOWN INTO THE
5-15 KNOT RANGE BUT RETURN TO GUSTY FROM THE WEST AFTER DAYBREAK
ON SUNDAY.
MARINE
ISSUED AT 221 PM EDT SAT APR 18 2026
A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH SUNDAY MORNING.
WIND GUSTS TO AROUND 25 KNOTS AND 3-6 FOOT WAVES CONTINUE THROUGH
THE EVENING AND INTO SUNDAY MORNING. CONDITIONS IMPROVE FOR THE
EARLY PART OF NEXT WEEK AS HIGH PRESSURE MOVES INTO THE REGION.
HYDROLOGY
ISSUED AT 221 PM EDT SAT APR 18 2026
MAJOR FLOODING CONTINUES ON THE MUSKEGON RIVER. THE GOOD NEWS IS
MOST LOCATIONS HAVE CRESTED OR ARE CRESTING NOW. IT WILL LIKELY
TAKE UNTIL LATE NEXT WEEK FOR ALL LOCATIONS TO COME UNDER FLOOD
STAGE, SO THE RECOVERY PROCESS WILL BE SLOW. MEANWHILE, WATER
LEVELS CONTINUE TO RISE ON THE GRAND RIVER, AND CONFIDENCE IS
INCREASING THAT THIS WILL END UP BEING ANOTHER MINOR FLOOD EVENT,
SLIGHTLY HIGHER AND WORSE THAN THE ONE THAT HAPPENED EARLIER THIS
MONTH, BUT NOT A RECORD FLOOD AT ANY LOCATIONS. HOWEVER, SOME OF
THE LOWEST AND EASILY FLOODED LOCATIONS ON THE RIVER LIKE COMSTOCK
PARK AND ROBINSON TOWNSHIP WILL HAVE MODERATE FLOODING. DRY
CONDITIONS ARE EXPECTED THROUGH THE NEXT SEVERAL DAYS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...FROST ADVISORY FROM 2 AM TO 10 AM EDT SUNDAY FOR MIZ050>052-
056>059-064>067-071>074.
FREEZE WATCH FROM SUNDAY EVENING THROUGH MONDAY MORNING FOR
MIZ050>052-056>059-064>067-071>074.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT SUNDAY FOR LMZ844>849.
DISCUSSION...THOMAS
AVIATION...DUKE
MARINE...THOMAS
HYDROLOGY...THOMAS
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