Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 230736
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
336 AM EDT SAT AUG 23 2014

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE

.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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1149 PM EDT FRI AUG 22 2014

I CONTINUED THE IDEA OF DENSE FOG DEVELOPING ACROSS ALL OF THE TAF
SITES OVERNIGHT. ALREADY MANY SITES HAVE MVFR FOG. THE NAMDNG5
SHOWS FOG SPREADING INLAND FROM LAKE HURON AS FAR WEST AND GRR BY
12Z SATURDAY MORNING. ALREADY IT IS ON TRACK AS IT SHOWS THE FOG
INITIALLY MOVING INLAND OVER NORTHERN LOWER MICHIGAN (0SC/APN)
WHICH IN FACT IS ALREADY HAPPENING. LIKE YESTERDAY THE LOW CLOUDS
AND FOG SHOULD BE SLOW TO LEAVE SATURDAY. IT MAY BE MID TO LATE
AFTERNOON BEFORE THE LOW CLOUDS MIX OUT.

&&

.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...WDM
HYDROLOGY...DUKE
MARINE...DUKE









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