462
FXUS63 KGRR 050558
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
158 AM EDT SUN APR 5 2026
KEY MESSAGES
- CHANCE OF STORMS THIS AFTERNOON
- COLDER SUNDAY-TUESDAY WITH LIGHT SNOW POSSIBLE
- SHOWERS/STORMS LATE WEEK
DISCUSSION
ISSUED AT 136 PM EDT SAT APR 4 2026
- CHANCE OF STORMS THIS AFTERNOON
A COLD FRONT EXTENDS SOUTH OVER LAKE MI ACROSS CHI AND SOUTH ALONG
THE IL/IN BORDER. RADAR SHOWS ABUNDANT SHOWERS MOVING NORTHEAST
ACROSS THE CWA AHEAD OF THE FRONT. THE MAIN CONCERN THIS AFTERNOON
IS THE THUNDERSTORM POTENTIAL. A WARM FRONT IS LIFTING NORTH
ACROSS THE SOUTHERN ROW OF COUNTIES AND THIS MAY RESULT IN THE FAR
SOUTHEAST CWA SEEING SOME WARMER MORE BUOYANT AIR FOR A FEW HOURS
LATE THIS AFTERNOON. CAMS INDICATE WE'LL SEE SOME CONVECTIVE
DEVELOPMENT, BUT STRONGER STORMS REMAINING SOUTH OF THE CWA.
EASTERN CALHOUN AND JACKSON COUNTIES HAVE THE HIGHEST LIKELIHOOD
OF SEEING A STRONGER STORM THIS AFTERNOON WHERE MUCAPE VALUES ARE
CLOSER TO 800 J/KG. ONCE THE COLD FRONT SWEEPS THROUGH LATE
AFTERNOON, THAT'LL PUT AN END TO THE THUNDER THREAT.
- COLDER SUNDAY-TUESDAY WITH LIGHT SNOW POSSIBLE
ONCE THE COLD FRONT MOVES THROUGH, TEMPERATURES WILL DROP. H8
TEMPERATURES AROUND 12C THIS AFTERNOON WILL FALL TO -8C BY SUNDAY
MORNING AND -14C BY TUESDAY MORNING AFTER A SECONDARY COLD FRONT.
LAKE EFFECT RAIN/SNOW SHOWERS WILL DEVELOP AND MOVE INLAND SUNDAY.
SOME WET SNOW WILL MIX IN WITH THE SHOWERS. HIGHEST CHANCE TO SEE
SOME SNOW IS LATER MONDAY AND MONDAY NIGHT AFTER THE SECONDARY
COLD FRONT MOVES THROUGH. MINOR ACCUMULATIONS ARE POSSIBLE, MAINLY
OVER THE NORTHERN PORTIONS OF THE CWA. HIGHS SUNDAY THROUGH
TUESDAY WILL BE IN THE LOWER TO MID 40S.
- SHOWERS/STORMS LATE WEEK
ANOTHER COLD FRONT IS PROGD TO MOVE ACROSS THE STATE THURSDAY AND
POTENTIALLY STALL OUT OVER THE CWA. SIMILAR TO LAST WEEK, WE COULD
SEE A COUPLE ROUNDS OF SHOWERS AND THUNDERSTORMS AS WAVES OF LOW
PRESSURE RIDE NORTHEAST ALONG THE FRONTAL BOUNDARY AND THIS COULD
EXACERBATE ONGOING FLOODING ACROSS THE REGION. OF COURSE, IF PARTS
OF THE CWA COULD REMAIN IN THE WARM SECTOR, THEN CHANCES FOR
STRONG TO SEVERE STORMS WOULD ALSO INCREASE AND IT'S SOMETHING
WE'LL BE WATCHING.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 158 AM EDT SUN APR 5 2026
MOST LOCATIONS ARE STARTING OFF THIS FORECAST PERIOD WITH SOME
GUSTY WINDS FROM THE W, AND MAINLY VFR CONDITIONS. INDICATIONS ARE
THAT A LOWER CLOUD DECK AROUND 2500 FT WILL SPREAD ACROSS THE
TERMINALS THIS MORNING. IN ADDITION, MID-LATE MORNING WE WILL SEE
A CHANCE OF A FEW SNOW SHOWERS. WE ARE NOT EXPECTING ANY
SIGNIFICANT REDUCTION IN VISIBILITIES, AND THE SNOW SHOWERS SHOULD
MOVE OUT BY MID-AFTERNOON. MVFR CEILINGS ARE LIKELY TO HOLD ON
THROUGH MUCH OF THE DAY, THEN BECOMING VFR AS WE SEE DRIER AIR
MOVE IN.
WINDS WILL DIMINISH LATE IN THE AFTERNOON TO LESS THAN 12 KNOTS.
CONDITIONS WILL STAY VFR UNTIL POSSIBLY MID-LATE AFTERNOON. WE
COULD SEE A FEW LIGHT SHOWERS OR SPRINKLES AT THE END OF THIS
FORECAST PERIOD WITH ANOTHER WAVE MOVING IN.
MARINE
ISSUED AT 136 PM EDT SAT APR 4 2026
ONCE THE COLD FRONT MOVES ACROSS THE LAKE AROUND 6 PM, WINDS WILL
BECOME WESTERLY AND GUSTY. WAVES WILL INCREASE ACCORDINGLY TO
AROUND 7-8 FEET BY SUNDAY MORNING. WINDS WILL DIMINISH SUNDAY
AFTERNOON AND WAVES WILL DECREASE; THE SMALL CRAFT ADVISORY
REMAINS IN EFFECT UNTIL 8 PM SUNDAY.
ANOTHER COLD FRONT WILL MOVE ACROSS THE LAKE MONDAY AND WAVES WILL
INCREASE AGAIN. ANOTHER SMALL CRAFT ADVISORY MAY BE NEEDED THEN.
HYDROLOGY
ISSUED AT 136 PM EDT SAT APR 4 2026
RAINFALL OF 1-3 INCHES ACROSS SOUTHWEST MICHIGAN IN THE PAST 24
HOURS ADDS TO THE PREVIOUS ACCUMULATIONS FOR A ROUGHLY 4-6 INCH
RAINFALL TOTAL OVER THE LAST WEEK. ADDITIONAL RAINFALL WILL
GENERALLY BE 0.25" OR LESS THROUGH MID AFTERNOON, THOUGH UP TO 1" IS
POSSIBLE UNDER ANY THUNDERSTORMS. THIS RAINFALL FOR THE MOST PART
SHOULD NOT SIGNIFICANTLY EXACERBATE THE POOR DRAINAGE FLOODING THAT
DEVELOPED THIS MORNING.
WITH THE HEAVIEST RAIN ACROSS THE GRAND RIVER BASIN, THIS WILL LEAD
TO RIVER FLOODING OVER THE NEXT SEVERAL DAYS. RIVER FLOOD WARNINGS
HAVE BEEN ISSUED FOR THE GRAND RIVER AND ITS TRIBUTARIES IN LANSING,
THE PORTAGE RIVER AT VICKSBURG, THE MUSKEGON RIVER AT NEWAYGO AND
BRIDGETON, THE GRAND RIVER AT COMSTOCK PARK, AND THE THORNAPPLE
RIVER AT CALEDONIA AND HASTINGS. FOR THE MOST PART RIVERS WILL PEAK
AT MINOR FLOOD STAGE, WITH THE EXCEPTION OF COMSTOCK PARK AND
ROBINSON TOWNSHIP (THE LATTER OF WHICH IS IN A WATCH) WHERE MODERATE
FLOODING IS FORECAST.
THE HIGH WATER WILL WORK ITS WAY THROUGH GRAND RIVER SYSTEM OVER THE
NEXT SEVERAL DAYS, WITH FLOODING FORECAST ALONG THE GRAND RIVER FROM
IONIA TO GRAND RAPIDS, TO ROBINSON TOWNSHIP. GIVEN FLOODING IS 48-96
HOURS AWAY FOR THESE AREAS, RIVER FLOOD WATCHES HAVE BEEN ISSUED,
WITH THE POTENTIAL FOR WARNINGS AS WE GET CLOSER TO THE EVENT.
NUMEROUS OTHER RIVERS WILL REACH ACTION STAGE OVER THE COMING DAYS,
SOME LIKE THE MUSKEGON RIVER AT EVART GETTING CLOSE TO MINOR FLOOD
STAGE. PEOPLE NEAR AREA RIVERS SHOULD MONITOR THE LATEST NATIONAL
WEATHER SERVICE FORECASTS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ844>849.
DISCUSSION...04
AVIATION...NJJ
MARINE...04
HYDROLOGY...THOMAS
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