836  
FXUS63 KGRR 160808  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
408 AM EDT THU OCT 16 2025  
   
KEY MESSAGES  
 
- POTENTIAL FOR SOME LIGHT PRECIPITATION TONIGHT INTO FRIDAY  
 
- A WET AND WINDY WEEKEND  
 
- ANOTHER SYSTEM SET FOR TUESDAY/WEDNESDAY  
 
 
   
DISCUSSION  
 
ISSUED AT 408 AM EDT THU OCT 16 2025  
 
- POTENTIAL FOR SOME LIGHT PRECIPITATION TONIGHT INTO FRIDAY  
 
TODAY WILL BRING RATHER CALM AND QUIET WEATHER TO THE REGION AS  
HIGH PRESSURE IS IN PLACE BOTH AT THE SURFACE AND ALOFT. THE  
INITIAL PUSH OF WARM AIR ADVECTION IN ADVANCE OF OUR NEXT SYSTEM  
COMES TONIGHT INTO FRIDAY MORNING. THE BEST MOISTURE TRANSPORT  
OCCURS ACROSS NORTHERN LOWER MICHIGAN. THE SREF POPS ALMOST ALWAYS  
SEEM SUPERIOR TO OTHER GUIDANCE AND WILL FOLLOW ITS LEAD HERE. WE  
WILL CARRY SMALL POPS ACROSS CENTRAL LOWER MICHIGAN TO ACCOUNT  
FOR SHOWERS THAT WILL BE MOVING ACROSS THE AREA TONIGHT INTO  
TOMORROW MORNING.  
 
- A WET AND WINDY WEEKEND  
 
A COLD FRONT WILL BE LOCATED JUST WEST OF THE AREA IN THE FRIDAY  
NIGHT AND SATURDAY TIME FRAME ASSOCIATED WITH THE INITIAL WAVE  
MOVING INTO CANADA TODAY FROM THE PLAINS. A LITTLE BIT LESS IN THE  
WAY OF PRECIPITATION IS EXPECTED INITIALLY NOW, WITH A PERIOD OF  
DRY WEATHER EXPECTED AS WE AWAY FOR ENERGY TO DROP INTO THE BASE  
OF THE UPPER TROUGH AS WE HEAD INTO SATURDAY NIGHT. A DEEP LOW IS  
EXPECTED TO FROM IN THE GREAT LAKES THIS WEEKEND, BUT THE ENERGY  
THAT DRIVES AND DEEPENS THAT LOW IS CURRENTLY ALL THE WAY UP IN  
THE GULF OF ALASKA WEST OF BRITISH COLUMBIA CANADA. IT HAS A LONG  
WAY TO TRAVERSE BEFORE IT INDUCES A STRONG DEEPENING LOW INTO  
SUNDAY OVER THE GREAT LAKES. SO, WHILE THE NEARBY COLD FRONT WILL  
HAVE SOME RAIN ASSOCIATED WITH IT ON SATURDAY, THE BULK OF THE  
ACTIVITY GETS GOING WITH THE UPPER WAVE BEGINS TO ROUND THE BASE  
OF THE UPPER TROUGH TO OUR WEST SATURDAY EVENING. USING THE GFS,  
THE SURFACE LOW DEEPENS FROM 998MB IN IOWA SATURDAY EVENING TO  
989MB JUST NORTH OF LAKE HURON SUNDAY EVENING. THIS IS A STRONG  
LOW FOR SURE, BUT NOTHING THAT OUT OF THE ORDINARY BY THE  
STANDARDS OF FALL GREAT LAKES SYSTEMS. THE BACKSIDE HIGH IS NOT  
ABNORMALLY STRONG EITHER, AROUND 1020MB. THE EXPECTATIONS ARE FOR  
A WINDY SYSTEM THIS WEEKEND WITH SUSTAINED WINDS LIKELY IN THE  
20-30 MPH RANGE WITH GUSTS OF 40-50 MPH. WE ARE LIKELY LOOKING AT  
THE POTENTIAL OF A WIND ADVISORY ON SUNDAY AT LEAST FOR PORTIONS  
OF THE AREA. GIVEN THE DYNAMICS IN PLAY WITH A STRONG UPPER JET  
OVER 100 KNOTS AND THE MOISTURE RETURN OF 60+ F SURFACE DEWPOINTS,  
THUNDERSTORMS ARE EXPECTED IN THE WARM SECTOR SATURDAY NIGHT INTO  
SUNDAY MORNING. WPC QPF TOTALS ARE IN THE 1-2 INCH RANGE OVER THE  
NEXT 5 DAYS WITH MOST OF THAT COMING THIS WEEKEND. WE SHOULD BE  
ABLE TO HANDLE THAT RAIN WITHOUT ISSUES GIVEN LOWER RIVER LEVELS.  
 
- ANOTHER SYSTEM SET FOR TUESDAY/WEDNESDAY  
 
ANOTHER SYSTEM IS EXPECTED INTO MID NEXT WEEK IN THE TUESDAY AND  
WEDNESDAY TIME FRAME. THE DEEP UPPER TROUGH OF THIS WEEKEND IS  
FOLLOWED BY AN EVEN DEEPER UPPER SYSTEM AS WE HEAD INTO NEXT  
WEDNESDAY. THE UPPER TROUGH HAS A REINFORCING SHOT OF COLD AIR  
WITH 850MB TEMPERATURES DIPPING TO BELOW ZERO C. WIDESPREAD RAIN  
SHOWERS ARE EXPECTED ALONG WITH BLUSTERY CONDITIONS. FALL HAS  
ARRIVED!  
 
 
   
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/  
 
ISSUED AT 204 AM EDT THU OCT 16 2025  
 
SURFACE HIGH PRESSURE IS SPRAWLED ACROSS THE GREAT LAKES TONIGHT  
WHICH IS RESULTING IN LIGHT WINDS AND CLEAR SKIES. WE HAVE SOME  
OCCASIONAL GROUND FOG OCCURRING, FORMED THROUGH RADIATIONAL  
COOLING PROCESSES, BUT MOST SITES ARE VFR. WE EXPECT VFR WEATHER  
TO CONTINUE THROUGHOUT THE NEXT 24 HOURS ACTUALLY AS THE HIGH WILL  
ONLY HAVE SLIPPED SLIGHTLY TO THE EAST DURING THAT TIME.  
 
THE CLOUD BANK THAT IS OFF TO OUR WEST EARLY THIS MORNING WITH  
CLOUD BASES OF 3,500 TO 8,000 FEET WILL REMAIN WEST OF THE TAF  
SITES TODAY. SOME HIGH LEVEL CIRRUS CLOUDS WILL FILTER IN FROM  
THE WEST AFTER SUNRISE WITH BASES AT OR ABOVE 20,000 FEET.  
 
IN THE 00Z TO 06Z TIME FRAME THIS EVENING WE WILL SEE CLOUDS  
SPREAD IN FROM THE WEST WITH BASES AROUND 10,000 FEET. WINDS  
THROUGH THE TAF PERIOD OF 06Z TO 06Z WILL BE LIGHT, EITHER CALM  
(LIKE THIS MORNING) OR EAST TO SOUTHEAST AROUND 5 KNOTS TODAY.  
 
 
   
MARINE  
 
ISSUED AT 408 AM EDT THU OCT 16 2025  
 
LAKE MICHIGAN IS QUIET THIS MORNING WITH OFFSHORE WINDS AROUND 10  
KNOTS AND 1 FOOT WAVES. WINDS WILL BECOME EVEN LIGHTER TODAY SO  
NO MARINE CONCERNS THROUGH SUNSET. TONIGHT WINDS BEGIN TO PICK UP  
OUT OF THE SOUTH AT ABOUT 10 KNOTS AS SURFACE HIGH PRESSURE SLIPS  
AWAY TO THE EAST OF THE GREAT LAKES.  
 
ON FRIDAY WINDS WILL LIKELY INCREASE TO SMALL CRAFT ADVISORY (SCA)  
STRENGTH AS THE GRADIENT TIGHTENS BETWEEN THE RETREATING HIGH AND  
LOW PRESSURE IN THE NORTHERN PLAINS. 15 TO 30 KNOT SOUTH WINDS  
LOOK LIKE A REASONABLE BET FROM AROUND DAYBREAK ON FRIDAY INTO THE  
DAY ON SATURDAY. A SCA WILL BE NEEDED FOR FRIDAY INTO SATURDAY  
FOR THESE STRONGER SOUTH WINDS.  
 
THE FOCUS IS ON A THE POTENTIAL FOR STRONG WINDS OVER LAKE  
MICHIGAN THIS WEEKEND. THE EVOLUTION OF THE LOW IS THE QUESTION  
MARK AT THIS POINT. HOW AND WHERE THE LOW DEEPENS AND TO WHAT  
STRENGTH IS THE CRUX OF THE SATURDAY NIGHT THROUGH SUNDAY NIGHT  
FORECAST. THE ENERGY THAT WILL BE RESPONSIBLE FOR THIS WEEKENDS  
POTENTIALLY STRONG LOW IS IN THE GULF OF ALASKA THIS MORNING  
BETWEEN BRITISH COLUMBIA CANADA AND THE STATE OF ALASKA. SO, IT  
HAS A LONG WAY TO TRAVERSE AND MODELS ARE HANDLING ITS EVOLUTION  
DIFFERENTLY. AT THIS POINT LOOK AT BOTH OPERATIONAL AND ENSEMBLE  
GUIDANCE THE EVENT HAS THE POTENTIAL TO PRODUCE HIGH IN GALES (TO  
45 KNOTS) WITH SOME STORM FORCE GUSTS NOT OUT OF THE QUESTION  
(NEAR 50 KNOTS). THIS EVENT IS 4 DAYS OUT SO WE HAVE TIME TO DIAL  
IN THE FORECAST BASED ON NEW GUIDANCE. BOTTOM LINE, EXPECTING A  
HIGH END GALE ON SUNDAY WITH WAVES THAT WILL LIKELY PEAK IN THE  
12-15 FOOT RANGE.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...DUKE  
AVIATION...DUKE  
MARINE...DUKE  
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