Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 261146
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
746 AM EDT WED AUG 26 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT WED AUG 26 2015

ONE MORE COOL AND OVERCAST DAY WITH SCATTERED LIGHT SHOWERS CAN
BE EXPECTED AS A LARGE SLOW MOVING AREA OF LOW PRESSURE CONTINUES
TO IMPACT THE GREAT LAKES REGION.

THE LOW WILL FINALLY DEPART TONIGHT AND HIGH PRESSURE WILL MOVE
IN FOR THURSDAY... BRINGING BACK SOME SUNSHINE AND MILDER
TEMPERATURES. MORE CLOUDS AND SHOWERS WILL RETURN FOR THE
WEEKEND...ALTHOUGH TEMPERATURES WILL BE NEAR NORMAL.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT WED AUG 26 2015

THE BEST CHANCE OF ANY MEASURABLE PRECIP WILL BE THIS MORNING AS
FINAL VORTICTY MAXIMA DROP THROUGH THE BACK SIDE OF THE DEPARTING
UPPER TROUGH. STILL ONLY A FEW HUNDREDTHS OF AN INCH EXPECTED...
ESPECIALLY WEST AND SOUTHWEST OF GRR WHERE NW FLOW OFF THE WARM
WATERS OF LAKE MICHIGAN IS CREATING SOME LAKE ENHANCEMENT. DELTA T/S
BETWEEN THE LAKE AND H8 ARE STILL IN THE MID TEENS THIS MORNING.

CHALLENGING SKY FCST TONIGHT AS GUIDANCE SUGGESTS CLEARING SKIES
DUE TO INCOMING SUBSIDENCE WITH THE SFC RIDGE. TIMING AND EXTENT
OF CLEARING OF THE CURRENT CLOUD DECK IS LOW CONFIDENCE ATTM AND
EVEN IF IT DOES CLEAR WE RUN THE RISK OF SOME RADIATION LOW
STRATUS/FOG DEVELOPING OVERNIGHT. CURRENT SFC DEW POINTS IN THE
MID 50S PROBABLY WILL NOT FALL OFF MUCH TONIGHT AND WINDS WILL BE
LIGHT/CALM. STRONG RADIATIONAL COOLING WHERE SKIES CLEAR COULD
LEAD TO STRONG LOW LEVEL INVERSIONS SETTING UP WITH SFC TEMPS
FALLING BELOW THE CROSSOVER TEMP.

WILL MAINTAIN A MOSTLY SUNNY FCST FOR THURSDAY BUT AM A LITTLE
CONCERNED WE WILL SEE A FAIR AMOUNT OF SHALLOW DIURNAL CUMULUS
DEVELOPMENT AS A POCKET OF COOL H8 AIR AROUND 10C HANGS OVER THE
AREA. SUBSIDENCE UNDER THE RIDGE MAY OFFSET THIS SO WILL REMAIN
OPTIMISTIC FOR NOW.

SHORTWAVE APPROACHING FROM THE CENTRAL PLAINS WILL SEND A FAIR
AMOUNT OF MID AND HIGH LEVEL CLOUDINESS INTO THE AREA ON FRIDAY...
WITH PERHAPS EVEN SOME LIGHT SHOWERS/SPRINKLES ARRIVING BY LATE IN
THE DAY.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EDT WED AUG 26 2015

THE FOCUS DURING THE LONG TERM IS THE EVOLUTION OF A SFC LOW OVER
IOWA AND ITS MOVEMENT EASTWARD OVER THE WEEKEND.

BOTH THE GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT THAT A SFC
LOW WILL DEVELOP OVER THE PLAINS THURSDAY NIGHT AND THEN MOVE EAST
ACROSS IOWA AND WISCONSIN FRIDAY NIGHT AND SATURDAY. THE ECMWF IS
A BIT MORE DEVELOPED THAN THE GFS, LIKELY DUE TO BETTER SUPPORT
ALOFT. HOWEVER...BOTH MODELS FILL THE LOW AS IT MOVES TOWARD THE
CWA LATE SATURDAY. NOT REAL IMPRESSED WITH THIS SYSTEM, ALTHOUGH
IT`LL PROVIDE THE BEST CHANCE OF RAIN DURING THE LONG TERM.
THUNDERSTORM CHANCES ARE HIGHEST SATURDAY AFTERNOON WHEN LI/S FALL
TO AROUND -2C BUT WITHOUT STRONG INFLOW...LLJ IS LESS THAN 20
KTS...CAN`T SEE ANYTHING STRONG WITH THIS SYSTEM, THUS THE CHC
POPS.

AS THE SFC HIGH RETREATS THIS WEEKEND TEMPS WILL BEGIN TO WARM AGAIN
AND SUMMER WEATHER WILL RETURN BY LATE WEEKEND INTO EARLY NEXT WEEK.
HIGHS WILL CLIMB INTO THE MID 80S MONDAY AND TUESDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 746 AM EDT WED AUG 26 2015

NUMEROUS MVFR CIGS OF 1500-2500 FT ARE PRESENT THIS MORNING... AND
EVEN SOME ISOLATED IFR CIGS BELOW 1000 FT. CIGS SHOULD GRADUALLY
TREND UPWARD LATER TODAY TO VFR LEVELS... EVENTUALLY SCATTERING
OUT TONIGHT.

WE WILL HAVE TO WATCH FOR THE POSSIBILITY OF SOME IFR/LIFR
FOG/STRATUS DEVELOPING LATE TONIGHT. CONFIDENCE IN THIS SCENARIO
IS RELATIVELY LOW AT THIS TIME BUT FOR NOW WILL ADVERTISE SOME
LIGHT MVFR FOG AT ALL THE TAF SITES AFTER 06Z.

&&

.MARINE...
ISSUED AT 330 AM EDT WED AUG 26 2015

WINDS AND WAVES HAVE SUBSIDED AND ALL HEADLINES HAVE EXPIRED. WINDS
WILL REMAIN ON THE LIGHT SIDE THE NEXT FEW DAYS SO NO NEW HEADLINES
EXPECTED.


&&

.HYDROLOGY...
ISSUED AT 1240 PM EDT TUE AUG 25 2015

WITH LIGHT RAIN FORECAST INTO WEDNESDAY FOLLOWED BY DRY WEATHER
THURSDAY/FRIDAY AND MORE LIGHT RAIN FRIDAY NIGHT INTO SATURDAY...
RIVER LEVELS WILL REMAIN LOW INTO NEXT WEEK WITH NO FLOODING
CONCERNS.

&&

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

$$

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


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