500  
FXUS63 KGRR 261805  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
205 PM EDT FRI SEP 26 2025  
   
KEY MESSAGES  
 
- DRY AND MILD CONDITIONS TO PERSIST THROUGH NEXT WEEK  
 
 
   
DISCUSSION  
 
ISSUED AT 205 PM EDT FRI SEP 26 2025  
 
- DRY AND MILD CONDITIONS TO PERSIST THROUGH NEXT WEEK  
 
NO NEED FOR ANY CHANGES TO THE DRY AND MILD FORECAST THROUGH NEXT  
WEEK.  
 
A WEAK FRONT IS CURRENTLY DROPPING SOUTH THROUGH THE AREA THIS  
AFTERNOON. IT IS LOCATED NEAR A LINE FROM PENTWATER TO NORTHERN  
SAGINAW BAY AS OF 2 PM EDT/18Z. A FEW SPRINKLES WERE TRYING TO  
GENERATE ALONG M-55 JUST AFTER NOON, BUT THEY HAVE NOT GROWN TO  
ANYTHING MORE THAN THAT. THE BEST CHANCE FOR ANYTHING THIS AFTERNOON  
WITH BE CLOSER TO LAKE HURON/SAGINAW BAY WERE SOME LAKE BREEZE  
CONVERGENCE MAY HELP TO BOOST THE UPDRAFTS JUST ENOUGH.  
 
WE WILL LIKELY SEE SOME PATCHY FOG TONIGHT, ALTHOUGH IT WILL  
PROBABLY NOT BE AS EXTENSIVE AS LAST NIGHT/THIS MORNING. WE HAVE HAD  
A CHANCE TO MIX OUT SOME OF THE BOUNDARY LAYER MOISTURE THAT  
REMAINED YESTERDAY. IN ADDITION, THERE IS A LITTLE MORE WIND JUST  
OFF OF THE SFC. THIS WILL LEAD TO A LITTLE BIT MORE MIXING TO  
MITIGATE A PERFECT RADIATIONAL FOG SETUP.  
 
LOOKING MORE LONGER TERM, WE CONTINUE TO EXPECT UPPER RIDGING TO  
DOMINATE THE WEATHER OVER THE REGION THROUGH NEXT FRIDAY. THE RIDGE  
STILL LOOKS TO BE FAIRLY BROAD AND FLAT IN NATURE INTO MONDAY. IT IS  
BEING FLATTENED BY A STRONGER UPPER LOW ACROSS WESTERN ONTARIO. WE  
WILL HOLD ON TO MAINLY CLEAR SKIES, ANOTHER WEAK FRONT WILL DROP  
THROUGH THE AREA ON SUNDAY. THERE WILL NOT BE MUCH CHANGE IN THE AIR  
MASS. IT WILL JUST ACT TO SUPPRESS THE REALLY WARM AIR TO OUR SW  
UNDER THE HEART OF THE RIDGE.  
 
THE RIDGE DOES AMPLIFY EARLY NEXT WEEK, HELPING TO REINFORCE THE  
STRONG SUBSIDENCE OVER THE AREA AND VERY MILD TO WARM TEMPERATURES.  
THIS STRENGTHENING OF THE UPPER RIDGE COMES AS IT GETS SQUEEZED BY A  
STRONG UPPER LOW COMING INTO THE WESTERN U.S. AND THE TROPICAL  
SYSTEM THAT COULD COME INTO THE EAST COAST. IT LOOKS TO HOLD STEADY  
OVER US.  
 
THE 500 MB HEIGHTS INCREASE TO ALMOST 590 DAM. THIS NORMALLY WOULD  
BRING HIGHS WELL INTO THE 80S AND APPROACH 90F. HOWEVER, THE WAY THE  
SFC RIDGE ORIENTS ITSELF, WE WILL DEVELOP A LOW LEVEL NE FLOW THAT  
WILL FUNNEL IN A MORE SHALLOW COOLER AIR MASS FROM EASTERN CANADA.  
THIS WILL BRING TEMPERATURES DOWN A LITTLE INTO THE MID 70S, VERSUS  
THE 80 DEGREE TEMPS EXPECTED EARLY IN THE WEEK.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/  
 
ISSUED AT 109 PM EDT FRI SEP 26 2025  
 
VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING WITH SCATTERED  
DAYTIME CU AROUND 4KFT ACROSS WEST MICHIGAN. TONIGHT, CONDITIONS  
WILL BE FAVORABLE FOR PATCHY FOG DEVELOPMENT AS SKIES REMAIN  
CLEAR AND WINDS SUBSIDE. HAVE ADDED MVFR RESTRICTIONS AT  
MKG/AZO/LAN WHERE BETTER LOW-LEVEL RH WILL BE AND SLIGHTLY WEAKER  
WINDS ALOFT WILL BE PRESENT. BEST POTENTIAL FOR FOG DEVELOPMENT  
LOOKS TO BE ACROSS CENTRAL LOWER MICHIGAN TO THE NORTH OF THE  
TERMINALS. FURTHER SOUTH, HAVE GONE WITH NO RESTRICTIONS AT THIS  
TIME, AND WILL MONITOR DEWPOINT TRENDS THROUGH THE AFTERNOON TO  
SEE IF ANY MAY BE NEEDED IN SUBSEQUENT UPDATES. LOOK FOR WEST  
WINDS AROUND 5 KNOTS TODAY BECOMING LIGHT AND VARIABLE OVERNIGHT;  
BEFORE INCREASING FROM THE SOUTHWEST ON SATURDAY TO AROUND 5-10  
KNOTS.  
 
 
   
MARINE  
 
ISSUED AT 205 PM EDT FRI SEP 26 2025  
 
CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY/BEACH  
HAZARDS STATEMENT LEVELS THE NEXT SEVERAL DAYS AS A WEAK GRADIENT IS  
IN PLACE ACROSS THE AREA. NORTH WINDS TODAY WILL FLIP TO  
SOUTHWESTERLY SATURDAY. WINDS WILL PEAK EACH AFTERNOON AT AROUND 10-  
15 KNOTS AS SOME LAKE BREEZE ENHANCEMENT OCCURS ALONG THE SHORELINE.  
THERE IS ALSO A SIGNAL FOR A WIND ENHANCEMENT EARLY SUNDAY MORNING  
OF AROUND 10-15 KNOTS NEAR BIG AND LITTLE SABLE POINTS AS A WIND  
MAXIMA MOVES SOUTH ACROSS THE LAKE. EXPECT DRY CONDITIONS ACROSS THE  
WATERS.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...NJJ  
AVIATION...THOMAS  
MARINE...THOMAS  
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