Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271819
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
219 PM EDT THU AUG 27 2015

LATEST 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 1034 AM EDT THU AUG 27 2015

CONTINUED THE THEME OF PARTLY SUNNY OR BECOMING PARTLY SUNNY IN
THE MORNING UPDATE. CONFIDENCE IS NOT HIGH IN THIS OCCURRING
THOUGH GIVEN FAIRLY EXTENSIVE STRATOCU AS 1030AM. SATELLITE DOES
SHOW INDICATIONS THAT IT IS TRYING TO ERODE AS 850MB RIDGING
TAKES HOLD. BUT...CUMULUS SCHEME INDICATES WE SHOULD SEE BROKEN CU
DEVELOP IN BREAKS THAT OCCUR. HIGHS IN THE LOWER 70S LOOK
REASONABLE IF WE CAN GET SOME SUNSHINE.

&&

.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 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 219 PM EDT THU AUG 27 2015

CEILINGS HAVE BECOME MORE CELLULAR DUE TO DIURNAL HEATING AND
HAVE EVEN SCATTERED OUT IN SOME AREAS. CEILINGS ARE VFR ACROSS
CENTRAL LOWER MICHIGAN AND ARE STILL MVFR ACROSS SOUTH CENTRAL
LOWER MICHIGAN. HAVE TEMPO GROUPS AT SOME OF THE TAF SITES FOR A
FEW HOURS TO COVER THE MVFR CEILINGS BEFORE THEY LIFT ABOVE 3000FT
DUE TO ADDITIONAL HEATING.

TONIGHT FEEL CEILINGS WILL SCATTER OUT AREA WIDE AND LEAVE VFR
CONDITIONS IN PLACE. THERE IS A THREAT FOR FOG OVERNIGHT...LEFT IT
OUT OF THE TAFS AT THIS POINT...BUT COULD SEE THE NEED TO ADD IT
MOVING FORWARD. FRIDAY SHOULD BE VFR IN THE MORNING AFTER ANY FOG
LIFTS.


&&

.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 101 PM EDT THU AUG 27 2015

WITH DRY WEATHER EXPECTED THROUGH FRIDAY AND UNDER AN INCH OF RAIN
OVER THE WEEKEND... RIVER LEVELS SHOULD REMAIN LOW INTO NEXT WEEK
WITH NO FLOODING CONCERNS.

&&

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

$$

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


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