Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271118
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
718 AM EDT THU AUG 27 2015

LATEST UPDATE...
UPDATE/AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT THU AUG 27 2015

HIGH PRESSURE WILL BRING PARTLY CLOUDY SKIES AND MILDER TEMPERATURES
TODAY. A LOW PRESSURE SYSTEM MOVING EAST FROM THE CENTRAL PLAINS
WILL BRING INCREASING CLOUDS ON FRIDAY THEN NUMEROUS SHOWERS AND
THUNDERSTORMS OVER THE WEEKEND. A SIGNIFICANT WARM UP IS EXPECTED
NEXT WEEK WITH HIGHS REACHING WELL INTO THE 80S FROM MID WEEK INTO
LABOR DAY WEEKEND.

&&

.UPDATE...
ISSUED AT 718 AM EDT THU AUG 27 2015

WILL MAKE SOME ADJUSTMENTS TO THE SKY FORECAST FOR TODAY AS
LATEST FOG CHANNEL SHOWS EXTENSIVE STRATUS COVERING THE AREA
EARLY THIS MORNING. IN GENERAL WILL HAVE CLOUDY SKIES EARLY THIS
MORNING THEN PARTLY SUNNY. DIURNAL CUMULUS SCHEMES SUGGEST
CEILINGS WILL STAY BROKEN THIS AFTERNOON WITH THE EXCEPTION OF THE
LK MI COASTLINE.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT THU AUG 27 2015

EVEN THOUGH WE HAVE SFC RIDGING TODAY A MOSTLY SUNNY FORECAST IS NOT
A SLAM DUNK. FIRST OF ALL WE HAVE NOT COMPLETELY LOST THE PERSISTENT
CLOUD DECK OF THE LAST FEW DAYS. AS OF 3 AM IT IS STILL OVERCAST
NORTH OF A LINE FROM LUDINGTON TO FLINT AND IT LOOKS TO BE EXPANDING
BACK TO THE SOUTH AGAIN. WHERE SKIES ARE CLEAR SOUTH OF THIS LINE WE
HAVE SEEN SOME PATCHY FOG AND LOW STRATUS CLOUDS DEVELOP WITH SOME
VSBYS BELOW 1/2 MILE AND THIS MAY CONTINUE TO EXPAND THROUGH
DAYBREAK.

MEANWHILE A POCKET OF COOL H8 TEMPS AROUND 8C IS PROGGED TO HANG
AROUND TODAY... RELATED TO THERMAL TROUGHING STILL EXTENDING BACK TO
THE SOUTHWEST FROM OUR OLD UPPER LOW IN ERN CANADA. DIURNAL CUMULUS
SCHEMES SUGGEST A BROKEN CUMULUS DECK DEVELOPING WITH THE EXCEPTION
OF THE LAKE MICHIGAN SHORELINE TODAY ALTHOUGH SUBSIDENCE MAY OFFSET
THIS A BIT. WILL MAINTAIN THE MOSTLY SUNNY FORECAST BUT CONFIDENCE
IS NOT HIGH.

AFTER TODAY THE ATTENTION TURNS TO THE SHORTWAVE APPROACHING FROM
THE WEST FRIDAY AND SATURDAY. INITIALLY THIS FEATURE SENDS
CONSIDERABLE MID AND HIGH LEVEL CLOUDS INTO THE AREA FRIDAY...
FOLLOWED BY HIGH PROBABILITIES FOR SHOWERS AND TSTMS ON SATURDAY
AS PWATS SURGE OVER 1.5 INCHES. IN FACT WE WILL HAVE TO WATCH FOR
THE POSSIBILITY OF SOME STRONGER STORMS ON SATURDAY AFTERNOON AS
WE GET INTO THE WARM SECTOR OF THE SFC CYCLONE WITH THE SFC LOW
PASSING ACROSS THE MKE AREA. GUIDANCE SUGGESTS CAPES UP TO 1500
J/KG MAY BE ACHIEVED AFTER 18Z SAT SOUTH AND EAST OF GRR AND THERE
IS A SWLY LOW LEVEL JET OF AROUND 30-35KTS PROGGED.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT THU AUG 27 2015

IT/S LOOKING LIKE A PRETTY DRY PERIOD WITH INCREASING TEMPERATURES
THROUGH MID WEEK.

THE MAIN FOCUS CONTINUES TO BE THE DEVELOPMENT OF A SFC LOW IN THE
PLAINS THAT MOVES EAST TOWARD THE GREAT LAKES BY THE WEEKEND. THE
MODELS HAVE BEEN PRETTY CONSISTENT IN MOVING THE LOW ENE TOWARD
WISCONSIN BY FRIDAY AND THEN OVER LOWER MICHIGAN SATURDAY. LATEST
ITERATION OF THE GFS SHOWS A BIT OF A CHANGE IN THAT IT NOW MOVES
THE LOW ACROSS SRN LWR INSTEAD OF CENTRAL INDIANA. THE MAIN CHANGE
IN THE ECMWF HAS BEEN A DEEPENING OF THE UPPER TROUGH ASSOCIATED
WITH THE LOW. HOWEVER GIVEN THE TRACK OF THE LOW ACROSS NRN LWR WE
MIGHT NOT SEE MUCH PCPN FROM IT...ESPECIALLY BY SATURDAY NIGHT AS IT
MOVES AWAY FROM THE CWA. WE/LL MAINTAIN CHC POPS SATURDAY NIGHT AND
THEN DRY THINGS OUT THROUGH MID WEEK.

A BUILDING UPPER RIDGE ACROSS THE PLAINS THEN NOSES INTO THE GREAT
LAKES. H8 TEMPS CLIMB TO NEAR 20C BY MID WEEK WHICH WILL SEND SFC
TEMPS TO THE MID TO UPPER 80S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 718 AM EDT THU AUG 27 2015

WIDESPREAD MVFR CIGS AROUND 2500 FT EXPECTED THIS MORNING
ALTHOUGH SOME AREAS OF IFR/LIFR FOG AND LOW STRATUS ALONG AND
SOUTH OF THE I-94 CORRIDOR THROUGH 13-14Z.

LOOK FOR BKN CIGS TO GRADUALLY LIFT TO VFR LEVELS THIS AFTERNOON
FOLLOWED BY CLEARING TONIGHT. SOME PATCHY FOG MAY REDEVELOP LATE
TONIGHT BUT CONFIDENCE LOW AT THIS TIME SO LEFT OUT FOR NOW.

&&

.MARINE...
ISSUED AT 330 AM EDT THU AUG 27 2015

THERE ARE NO MARINE CONCERNS AT THIS TIME WITH LOOSE PRESSURE
GRADIENT IN PLACE.


&&

.HYDROLOGY...
ISSUED AT 227 PM EDT WED AUG 26 2015

WITH DRY WEATHER EXPECTED TONIGHT THROUGH FRIDAY AND ONLY LIGHT RAIN
FRIDAY NIGHT INTO SATURDAY... RIVER LEVELS SHOULD REMAIN LOW INTO
NEXT WEEK WITH NO FLOODING CONCERNS.

&&

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

$$

UPDATE...MEADE
SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...04
AVIATION...MEADE
HYDROLOGY...63
MARINE...MEADE


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