400
FXUS63 KGRR 070749
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
249 AM EST FRI NOV 7 2025
KEY MESSAGES
- RAIN WITH SOME THUNDERSTORMS THIS MORNING
- RAIN CHANGING TO SNOW SATURDAY NIGHT
- LAKE EFFECT SNOW LATE SUNDAY INTO MONDAY
DISCUSSION
ISSUED AT 249 AM EST FRI NOV 7 2025
- RAIN WITH SOME THUNDERSTORMS THIS MORNING
CURRENT RADAR AND SATELLITE SHOW A BAND OF PRECIPITATION ENTERING
WESTERN LOWER MI FROM LAKE MICHIGAN. THERE HAS BEEN SOME LIGHTNING
WITH THIS ACTIVITY IN THE VICINITY OF THE SABLE POINTS AMIDST THE
COMBINED EFFECTS OF DESTABILIZATION FROM STRONG LOW LEVEL MOIST
TRANSPORT AND MESOSCALE ASCENT AHEAD OF A TIGHT UPPER PV MAX
CROSSING WI PER WATER VAPOR IMAGERY. IT SHOULD BE NOTED THAT THE
SPC MESOANALYSIS SEEMS TO BE HAVING DIFFICULTY WITH ASSESSING THE
CONDITIONAL INSTABILITY GIVEN MUCAPE PROGS ARE LESS THAN 100 J PER
KG IN AREAS WHERE LIGHTNING HAS BEEN OBSERVED. REGARDLESS, THIS
BAND OF PRECIPITATION WILL QUICKLY TRAVERSE THE FORECAST AREA
EARLY TODAY, YIELDING DRY CONDITIONS BY THIS AFTERNOON.
- RAIN CHANGING TO SNOW SATURDAY NIGHT
SNOW IS EXPECTED TO FINALLY ARRIVE SATURDAY NIGHT WITH AN UPPER PV
MAXIMUM AND ATTENDANT SURFACE LOW CROSSING IL/IN INTO THE OH VALLEY
REGION. A DEEP LAYER OF ISENTROPIC ASCENT JUST POLEWARD OF THE SURFACE
LOW TRACK WILL BE IN PLACE WITH GREATEST ACCUMULATIONS...OF CHIEFLY
1 TO 2 INCHES...ALONG OR JUST SOUTH OF A KALAMAZOO TO LANSING LINE.
MOST ACCUMULATIONS WOULD OCCUR BETWEEN MIDNIGHT AND SUNRISE SUNDAY.
THIS AREA AND MAGNITUDE ARE BOTH SUBJECT TO CHANGE AND WILL BE MODERATED
BY THE LOW TRACK AND HOW QUICKLY TEMPERATURES COOL. THE SNOW WILL BE
QUITE WET AND SLOPPY BASED ON FORECAST SOUNDINGS THAT INDICATE THE
STRONGEST ISENTROPIC ASCENT WILL BE CONCENTRATED UNDERNEATH THE DGZ
AND NEAR SURFACE TEMPERATURES WILL ALSO BE HOVERING AROUND FREEZING.
AS NOTED IN PREVIOUS DISCUSSIONS, THERE IS SOME QUESTION REGARDING
ACCUMULATION EFFICIENCY OVER PAVEMENT GIVEN THAT SURFACE TEMPERATURES
WILL INITIALLY BE WARM. AS ALSO NOTED PREVIOUSLY, SOME IMPACTS
SUNDAY MORNING ARE NOT OUT OF THE QUESTION IN TERMS OF SLIPPERY
OVERPASSES AND PERHAPS POWER INTERRUPTIONS FROM WET SNOW WEIGHING
DOWN BRANCHES STILL CONTAINING LEAVES.
- LAKE EFFECT SNOW LATE SUNDAY INTO MONDAY
SNOW WILL BE MUCH FLUFFIER BY SUNDAY NIGHT AND MONDAY MORNING AS WE
ENTER A LAKE EFFECT REGIME THANKS TO A REINFORCING UPPER TROUGH WITH
EVEN COLDER AIR. NORTH-NORTHWESTERLY FLOW WILL KEEP GREATEST
ACCUMULATIONS TIED TO FAR SOUTHWEST LOWER MI INCLUDING VAN BUREN AND
WESTERN ALLEGAN COUNTIES AND THE SABLE POINTS LASTING WELL INTO AND
BEYOND THE MONDAY MORNING COMMUTE. EXPERIMENTAL NBM V5.0 GUIDANCE
FURTHER SUGGESTS THE SABLE POINTS MAY SEE THE GREATEST ACCUMULATIONS
THANKS TO PARTICULARLY FAVORABLE CONDITIONING OFF LAKE SUPERIOR.
TRAVEL IMPACTS COULD BE MORE OF AN ISSUE WITH LOW TEMPERATURES
MONDAY MORNING REACHING THE LOWER 20S OR COLDER.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1214 AM EST FRI NOV 7 2025
VFR CONDITIONS WILL BECOME MVFR OVERNIGHT AS RAIN MOVES ACROSS
LOWER MICHIGAN FROM WEST TO EAST, WITH AREAS OF IFR INTO EARLY
FRIDAY MORNING. SOUTHERLY LLWS WILL CONTINUE OVERNIGHT. SURFACE
WINDS WILL GUST OVER 20 KNOTS TONIGHT THROUGH FRIDAY EVENING.
MARINE
ISSUED AT 249 AM EST FRI NOV 7 2025
NO CHANGES TO PREVIOUS THINKING. WILL KEEP THE GALE WARNING IN
EFFECT AND THIS WILL TRANSITION TO A SMALL CRAFT ADVISORY LATER
TODAY.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...GALE WARNING UNTIL 10 AM EST THIS MORNING FOR LMZ844>849.
DISCUSSION...TJT
AVIATION...OSTUNO
MARINE...TJT
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page