349
FXUS63 KGRR 292321
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
721 PM EDT WED OCT 29 2025
KEY MESSAGES
- LAKE EFFECT SHOWERS THURSDAY NIGHT INTO THE WEEKEND
DISCUSSION
ISSUED AT 315 PM EDT WED OCT 29 2025
- LAKE EFFECT SHOWERS THURSDAY NIGHT INTO THE WEEKEND
AN UPPER LEVEL LOW WILL TRACK ACROSS THE OHIO RIVER VALLEY
THURSDAY BRINGING A SLIGHT CHANCE (20 PERCENT) FOR SHOWERS
IN EASTERN JACKSON AND INGHAM COUNTIES. OTHERWISE DRY CONDITIONS
HOLD UNTIL LOW TO MID LEVEL WINDS SHIFT TO THE NORTHWEST AHEAD OF
ANOTHER UPPER LEVEL LOW TRACKING FROM CANADA. WITH THE ORIENTATION
OF THE WINDS AND 850MB TO LAKE SURFACE TEMPERATURE DIFFERENCES
LAKE EFFECT SHOWERS ARE EXPECTED TO DEVELOP THURSDAY NIGHT AND
CONTINUE THROUGH SATURDAY. MOISTURE AND WIND ORIENTATION IS NOT
EXPECTED TO BE PERSISTENT DURING THIS TIME, THEREFORE THE
CONCENTRATION AND LOCATION OF SHOWERS IS EXPECTED TO CHANGE WITH
INLAND AREAS STAYING MOSTLY DRY. OVERALL NOT EXPECTING A WASHOUT
FOR HALLOWEEN, WITH BETTER CHANCES (50 TO 60 PERCENT) HOLDING OFF
UNTIL FRIDAY NIGHT ALONG THE LAKESHORE.
DRY CONDITIONS ARE EXPECTED SUNDAY AS THE LOW DIVES SOUTH, BUT
ANOTHER SHORTWAVE TROUGH LOOKS TO BRING ADDITIONAL CHANCES (20 TO
40 PERCENT) SUNDAY NIGHT INTO MONDAY. TEMPERATURES INTO NEXT WEEK
WILL BE AROUND NORMAL WITH HIGHS IN THE 50S AND LOWS IN THE 30S.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 721 PM EDT WED OCT 29 2025
DIURNAL CUMULUS ARE DIMINISHING AND WINDS BECOMING NORTHEASTERLY
AROUND 5 KNOTS. A ROBUST CIRRUS SHIELD IS EXPECTED TO MOVE OVER
THE AREA TONIGHT AS A LOW PRESSURE SYSTEM TRACKS SOUTHEAST OF THE
REGION. LATEST SHORT RANGE MODEL GUIDANCE FAVORS RAIN STAYING
SOUTHEAST OF THE TERMINALS. THERE ARE SIGNALS FOR LOW STRATUS
DEVELOPMENT, MAINLY AT LAN, AFTER 10Z AS A CONNECTION OFF OF
SAGINAW BAY/LAKE HURON FOR MOISTURE IS ESTABLISHED. HAVE ADDED A
PERIOD OF MVFR AT LAN FOR NOW WITH A MODERATE (40-60 PERCENT)
CHANCE OF STRATUS DEVELOPING. SIGNALS EXIST THAT SOME CLOUDS COULD
BE IFR OR LOWER, AND/OR IMPACT BTL, AZO, AND JXN, HOWEVER
CONFIDENCE IN THESE SCENARIOS IS LOW AT THIS TIME. ANY LOW CLOUDS
THAT DEVELOP WILL BURN OFF IN THE MID TO LATE MORNING. HOWEVER,
VFR CEILINGS ARE LIKELY THROUGH THE DAY AS THE CLOUD SHIELD
PROGRESSES ACROSS THE AREA. THE ONE EXCEPTION IS MKG WHO IS
FAVORED TO BE JUST OUTSIDE THE CLOUD SHIELD AND SEE MORE IN THE
WAY OF CLEAR SKIES. NORTHERLY WINDS AROUND 10 KNOTS DEVELOP
THURSDAY WITH AFTERNOON GUSTS TO AROUND 20 KNOTS.
MARINE
ISSUED AT 315 PM EDT WED OCT 29 2025
ISOLATED GUSTS AS HIGH AS 25 KNOTS WILL PERSIST THROUGH THE EVENING
SOUTH OF WHITEHALL. THEREFORE WILL LEAVE THE ONGOING SMALL CRAFT
ADVISORY IN PLACE WITH EXPIRATION LATER TODAY. INCREASING ONSHORE
FLOW WILL BEGIN LATER THURSDAY AND CONTINUE INTO SATURDAY AS A LOW
PRESSURE SYSTEM DEEPENS MOVING NORTH ACROSS THE APPALACHIANS. GIVEN
NORTHWEST FLOW TO AROUND 20 KNOTS, WITH LOCALLY HIGHER GUSTS, THE
AREA WITH THE GREATEST RISK FOR HAZARDOUS WINDS AND WAVES IS NEAR
AND SOUTH OF GRAND HAVEN. WITH A LULL IN WINDS FOR 15-18+ HOURS
TONIGHT INTO THURSDAY MORNING, WILL LET THE NEXT SHIFT HANDLE THE
FINAL HEADLINE DECISION WITH A SEPARATE ADVISORY IF NEEDED. WINDS
DIMINISH SUNDAY AS HIGH PRESSURE CROSSES THE AREA. CONDITIONS
HAZARDOUS TO SMALL CRAFT ARE THEN POSSIBLE MONDAY/TUESDAY AS A LOW
PRESSURE SYSTEM ACROSS CENTRAL CANADA INCREASES GRADIENT WINDS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ844>847.
DISCUSSION...RAH
AVIATION...THOMAS
MARINE...THOMAS
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