717  
FXUS63 KGRR 231152  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
752 AM EDT SAT AUG 23 2014  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 336 AM EDT SAT AUG 23 2014  
 
WARM AND MAINLY DRY WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH  
HIGHS IN THE 80S. CHANCES FOR SHOWERS AND STORMS CREEP BACK INTO THE  
FORECAST NEXT WEEK...ESPECIALLY DURING THE MIDDLE PORTION OF THE  
UPCOMING WORK WEEK. SOME OF THE WARMEST WEATHER OF THE SUMMER IS  
EXPECTED SUNDAY THROUGH TUESDAY WHERE HIGHS WILL REACH THE UPPER 80S  
TO AROUND 90 DEGREES.  
 

 
   
SHORT TERM
 
(TODAY THROUGH MONDAY)  
ISSUED AT 336 AM EDT SAT AUG 23 2014  
 
MAINLY DRY CONDITIONS ARE EXPECTED THROUGH THE SHORT TERM AS THE  
FOCUS FOR PRECIPITATION WILL BE WEST OF THE AREA. AN EASTERLY FLOW  
WILL TRY TO ADVECT SLIGHTLY DRIER AIR INTO THE FORECAST AREA. THE  
BUILDING UPPER LEVEL RIDGE OVERHEAD SHOULD SUPPRESS PRECIPITATION  
THROUGH THE SHORT TERM.  
 
THERE ARE TWO TIME FRAMES THOUGH WHERE WE MAY SEE SOME ISOLATED  
SHOWERS AND STORMS. THE FIRST IS THIS AFTERNOON WHERE UPSTREAM  
PRECIP ACROSS ILLINOIS TRIES TO PRESS IN FROM THE WEST. FEEL THE  
CHANCES ARE TOO LOW TO INCLUDE AND LEFT IT OUT OF THE FORECAST.  
 
THE NEXT TIME FRAME IS ON MONDAY AS A BOUNDARY BEGINS TO LEAN IN  
FROM THE NORTHWEST. HAVE ISOLATED CHANCES FOR SHOWERS AND STORMS  
ACROSS THE NORTHWEST HALF OF THE FORECAST AREA ON MONDAY TO ACCOUNT  
FOR THIS THREAT.  
 
THREAT FOR DENSE MORNING FOG SEEMS A LITTLE BIT LOWER THIS MORNING  
AS COMPARED TO YESTERDAY. WE HAVE A BIT MORE WIND THIS MORNING  
AROUND 1000FT. EXPECTING SOME PATCHES OF DENSE FOG BUT IT SHOULD NOT  
BE WIDESPREAD. IN FACT...MOST AREAS ARE STILL ABOVE 3 MILE  
VISIBILITIES THIS MORNING.  
   
LONG TERM
 
(MONDAY NIGHT THROUGH FRIDAY)  
ISSUED AT 336 AM EDT SAT AUG 23 2014  
 
DIFFERENCES REMAIN IN THE LONG TERM MODELS IN TERMS OF THE SURFACE  
PATTERN EVOLUTION ESPECIALLY. BOTH THE GFS AND THE ECMWF SHOW THE  
500MB RIDGE SLOWLY LOSING AMPLITUDE AS WE HEAD THROUGH THE UPCOMING  
WORK WEEK. THE GFS IS QUICKER AS IT DRIVES A TROUGH INTO THE GREAT  
LAKES THURS/FRI. THE ECMWF IS NOT AS BULLISH WITH THE TROUGH AND  
KEEPS FAIRLY HIGH HEIGHTS RIGHT THROUGH THE WEEK.  
 
AT THE SURFACE THE GFS BRINGS A SYSTEM THROUGH THE GREAT LAKES  
WED/THURS WHILE THE ECMWF HAS MORE OF A STATIONARY FRONT OVER THE  
SOUTHERN GREAT LAKES...JUST NORTH OF THE RIDGE AXIS. DIFFICULT CALL  
AT THIS POINT AS TO WHICH MODEL HAS A BETTER HANDLE. HAVE POPS  
MONDAY NIGHT THROUGH THURSDAY AT THIS POINT...WITH A DRY FRIDAY.  
CONFIDENCE IS LOW IN HOW THIS WILL PLAY OUT THOUGH.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)  
ISSUED AT 751 AM EDT SAT AUG 23 2014  
 
STRATUS AND FOG AT DAYBREAK IS NOWHERE NEAR AS EXTENSIVE AND THICK  
AS YESTERDAY. WE FEEL THIS IS DUE IN PART TO A LITTLE BIT BETTER  
WIND JUST OFF THE SURFACE (15KT EASTERLY WINDS AT 1000FT). THERE  
ARE PATCHES OF LIFR CEILINGS AND VISIBILITIES ALTHOUGH MOST OF  
THIS IS NORTH AND SOUTH OF THE TAF SITES.  
 
EXPECT ANY MORNING FOG AND STRATUS TO BURN OFF AND LIFT THROUGH  
15Z OR SO. BY MIDDAY MAINLY VFR CONDITIONS ARE EXPECTED...ALTHOUGH  
THERE MAY BE SOME PATCHES OF MVFR CEILINGS BETWEEN 2000-3000FT.  
PLAYED THE TAFS A BIT MORE OPTIMISTIC THOUGH AND WENT VFR FOR THE  
MIDDAY AND AFTERNOON HOURS.  
 
TONIGHT IS ANOTHER DIFFICULT FORECAST. AT THIS POINT LET THE VFR  
AFTERNOON CONDITIONS CARRY RIGHT THROUGH THE NIGHT. WINDS JUST OFF  
THE SURFACE AT 1000FT ARE JUST A BIT STRONGER...AROUND 20 KNOTS.  
THIS SHOULD PRECLUDE MUCH IN THE WAY OF FOG DEVELOPMENT. WE COULD  
SEE SOME STRATUS FORM AROUND 1500-2500FT...BUT DID NOT INCLUDE IN  
THE TAFS AT THIS POINT.  
 
EXPECTING DRY CONDITIONS THROUGH THE NEXT 24 HOURS...WITH A LIGHT  
EASTERLY WIND.  
 

 
   
MARINE
 
 
ISSUED AT 336 AM EDT SAT AUG 23 2014  
 
FAIRLY LIGHT WINDS ARE FORECAST THROUGH THE NEXT SEVERAL DAYS WITH  
AN OFF SHORE FLOW. SO...WINDS AND WAVES WILL NOT BE A CONCERN TO  
MARINE INTERESTS.  
 
FOG OVER THE LAKE WILL REMAIN A CONCERN HOWEVER AS DEW POINTS REMAIN  
IN THE UPPER 60S TO LOWER 70S MUCH OF THE NEXT SEVERAL DAYS. THE  
OFFSHORE FLOW MAY ACT TO KEEP DEW POINTS DOWN JUST A BIT THOUGH IN  
EASTERLY FLOW. THE REAL CONCERN WITH MARINE FOG MAY COME MON-WED AS  
SOUTHERLY FLOW BRINGS A GOOD SURGE OF LOW LEVEL MOISTURE OUT OVER  
THE LAKE.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 336 AM EDT SAT AUG 23 2014  
 
NO HYDRO ISSUES ANTICIPATED THE REMAINDER OF THE WEEKEND AS  
CONDITIONS ARE FORECAST TO REMAIN MOSTLY DRY. SHOWERS AND STORMS  
RETURN TO THE FORECAST DURING THE UPCOMING WORK WEEK...ESPECIALLY  
DURING THE MIDDLE PORTION OF THE WEEK. RAINFALL TOTALS COULD EXCEED  
ONE INCH IS SPOTS MON-FRI. RIVER LEVELS ARE RUNNING ABOVE  
NORMAL...ESPECIALLY IN THE GRAND RIVER BASIN...ALTHOUGH ALL SITES  
ARE CURRENTLY WITHIN BANK. WE SHOULD BE ABLE TO ABSORB CURRENT  
FORECAST RAINFALL AMOUNTS WITHOUT MUCH ISSUE. WE WILL BE MONITORING  
PRECIP TRENDS AS WE HEAD THROUGH THE UPCOMING WORK WEEK.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LM...NONE.  

 
 

 
 
SYNOPSIS...DUKE  
SHORT TERM...DUKE  
LONG TERM...DUKE  
AVIATION...DUKE  
HYDROLOGY...DUKE  
MARINE...DUKE  
 
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