133
FXUS63 KGRR 201004
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
604 AM EDT MON OCT 20 2025
KEY MESSAGES
- ROUND OF SHOWERS MONDAY NIGHT INTO TUESDAY
- SHOWERS AND POSSIBLE STORMS LATE TUESDAY INTO WEDNESDAY
- COOLER AND ACTIVE WEATHER THROUGH THE REST OF THE WEEK
DISCUSSION
ISSUED AT 330 AM EDT MON OCT 20 2025
- ROUND OF SHOWERS MONDAY NIGHT INTO TUESDAY
AN UPPER LEVEL RIDGE WILL BUILD OVER THE REGION TODAY WITH SOME
MILD WARM AIR ADVECTION. THAT WILL KEEP MAX TEMPS AROUND 60S,
WHICH IS NEAR NORMAL. THIS WILL CHANGE QUICKLY AS A NEGATIVELY
TILTED TROUGH WILL MOVE OUT AHEAD OF A LARGE BAROTROPIC UPPER
LEVEL LOW WHICH WILL MOVE THROUGH THE UPPER MIDWEST TUESDAY. THAT
TROUGH WILL BRING A NARROW BAND OF SHOWERS LATE TONIGHT, THROUGH
TUESDAY MORNING. WHILE THUNDER IS NOT EXPECTED, RAIN COULD BE
HEAVY AT TIMES WITH THE HEAVIEST RAIN ALONG AND THE US 10
CORRIDOR. WINDS WILL SHIFT FROM GUSTY SOUTHERLY FLOW EARLY TUESDAY
TO THE WEST TUESDAY AFTERNOON.
- SHOWERS AND POSSIBLE STORMS LATE TUESDAY INTO WEDNESDAY
AS THE LARGE UPPER LEVEL LOW MOVES THROUGH SOUTHERN CANADA AND THE
UPPER MIDWEST, A COLD FRONT WILL MOVE THROUGH ALONG WITH IT.
STRONG COLD WESTERLY FLOW WILL INFILTRATE THE REGION. THIS, ALONG
WITH A STRONG VORT MAX SHOULD ALLOW FOR LAKE ENHANCED SHOWERS
TUESDAY AFTERNOON INTO WEDNESDAY. THERE ISN'T LOT OF CAPE, HOWEVER
THERE COULD BE 100 TO 400 J/KG THAT, COUPLED WITH THE STRONG FLOW
OFF THE LAKE, COULD SPARK SOME STORMS ALONG THE LAKESHORE MAINLY
SOUTH OF WHITEHALL.
AFTER FRONTAL PASSAGE, TEMPS SHOULD DROP PRECIPITOUSLY WITH THE
COLD AIR ADVECTION. MAX TEMPERATURES SHOULD INTO THE LOW 50S TO
UPPER 40S. THAT WOULD DROP TEMPS 5 TO 10 DEGREES BELOW NORMAL
TUESDAY AND WEDNESDAY. THE LOW SHOULD MOVE SLOWLY TO THE WEST
WHICH WILL KEEP INTERMITTENT SHOWERS THROUGH WEDNESDAY.
- COOLER AND ACTIVE WEATHER THROUGH THE REST OF THE WEEK
THE UPPER LEVEL LOW WILL CONTINUE TO MOVE TO THE EAST, HOWEVER AS
IT DOES SO, IT WILL BRING SUCCESSIVE WAVES THROUGH THE REGION
WHICH WILL KEEP CHANCES FOR RAIN IN THE FORECAST INTO THE UPCOMING
WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 210 AM EDT MON OCT 20 2025
WINDS HAVE BECOME LIGHT WITH PERSISTENT WESTERLY FLOW CONTINUING
OVERNIGHT INTO TOMORROW. MAIN WEATHER CONCERN WILL BE LOW LEVEL
WIND SHEAR TOMORROW NIGHT OUT AHEAD OF THE ADVANCING SYSTEM.
EXPECT LLWS OF 40KTS OUT OF THE SOUTH FROM 03Z UNTIL 09Z TUESDAY.
WHILE JUST OUTSIDE OF THE TAF PERIOD, THERE WILL BE DECREASING
CIGS BETWEEN 06Z TO 12Z TUESDAY. DAYTIME TEMPS WILL REMAIN IN THE
50S THROUGH MOST OF THE WEEK AND SHOULD SLOWLY CLIMB BACK UP INTO
THE 60S NEXT WEEKEND.
MARINE
ISSUED AT 345 AM EDT MON OCT 20 2025
SMALL CRAFT ADVISORY WILL CONTINUE AS WAVES REMAIN HIGH AND GUSTY
SOUTHERLY WINDS RETURN WITH THE POTENTIAL FOR GALES MONDAY NIGHT
AHEAD OF OUR NEXT LOW PRESSURE SYSTEM. HAVE HELD OFF ON ANY GALE
WATCH AS THE POTENTIAL MONDAY NIGHT LOOKS SPORADIC.
HOWEVER, THERE IS A HIGHER PROBABILITY FOR GALES MID TUESDAY
INTO WEDNESDAY ON THE BACKSIDE OF THE LOW. WINDS SHOULD SWING
FROM THE SOUTHWEST TO THE NORTHWEST. GALES TO 40 KNOTS ARE LIKELY
DURING THIS PERIOD WITH A LOW CHANCE FOR STORM FORCE GUSTS. HIGH
WAVES AND GUSTY WINDS LINGER INTO THURSDAY WITH WATERS FINALLY
BECOMING CALMER BY THE END OF THE WEEK.
HYDROLOGY
ISSUED AT 311 PM EDT SUN OCT 19 2025
THE AREA GENERALLY SAW BETWEEN 1 AND 3 INCHES OF RAIN AS EXPECTED
FOR THE HEART OF THIS EVENT THAT IS NOW WINDING DOWN. THERE MAY HAVE
BEEN SOME LOCALIZED HEAVY AMOUNTS. WE HAVE NOT RECEIVED ANY IMPACTS
FROM THE RAIN.
THIS RAIN WAS GENERALLY VERY GOOD FOR THE ONGOING DROUGHT SITUATION
ACROSS THE AREA. THE RIVER AND STREAM LEVELS HAVE RESPONDED TO THE
RAIN, BUT THE RISES ARE LIKELY MUTED A BIT DUE TO THE VERY DRY DEEP
GROUND THAT LIKELY SOAKED UP A LOT OF THE RAIN, ESPECIALLY SINCE IT
WAS SPREAD OUT OVER 24-36 HOURS.
ADDITIONAL RAIN THIS WEEK DOES NOT LOOK HEAVY, SO THE RIVERS AND
STREAMS SHOULD CONTINUE TO BEHAVE.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR LMZ844>849.
DISCUSSION...CERU
AVIATION...CERU
MARINE...CERU
HYDROLOGY...NJJ
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