Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 250056
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
856 PM EDT MON AUG 24 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EDT MON AUG 24 2015

FALL LIKE WEATHER WILL CONTINUE THROUGH MIDWEEK WITH HIGH
TEMPERATURES ONLY IN THE 60S TO AROUND 70 DEGREES ALONG WITH
EXTENSIVE CLOUD COVER. SCATTERED RAIN SHOWERS WILL ALSO DEVELOP
TONIGHT THROUGH TUESDAY INTO WEDNESDAY. TEMPERATURES WILL FINALLY
UNDERGO A GRADUAL MODERATING TREND LATE IN THE WEEK INTO NEXT
WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 330 PM EDT MON AUG 24 2015

OUR PRIMARY SHORT TERM FCST CONCERN IS TO DETERMINE CHANCES FOR
LAKE EFFECT RAIN SHOWERS THROUGH MIDWEEK.

RATHER EXTENSIVE STRATOCU WILL LINGER TONIGHT AND SCATTERED
SHOWERS WILL DEVELOP FROM NORTH TO SOUTH LATE THIS AFTERNOON AND
EVENING AS H8 TEMPS CONTINUE TO FALL TO AROUND 4 TO 5 C BY LATE
EVENING. THIS WILL RESULTING IN MODERATE LAKE INDUCED INSTABILITY
AS DELTA T/S REACH THE MIDDLE TEENS.

THIS IN CONJUNCTION WITH SEVERAL UPPER LEVEL DISTURBANCES AND PVA
ROTATING AROUND THE VERTICALLY STACKED UPPER LOW OVER THE LAKE
SUPERIOR REGION WILL RESULT IN DEVELOPMENT OF SCATTERED SHOWERS
TONIGHT THROUGH TUESDAY. SHOWERS SHOULD BE MOST PREVALENT ACROSS
OUR NORTHERN FCST AREA IN CLOSER PROXIMITY TO THE STACKED UPPER
LOW AND WHERE DEEPER LOW TO MID LEVEL MOISTURE WILL RESIDE.

IT WILL REMAIN COOL WEDNESDAY ALONG WITH FAIRLY EXTENSIVE AMOUNT
OF LINGERING STRATOCU. THERE IS JUST A SMALL CHC FOR A FEW
LINGERING LIGHT RAIN SHOWERS AND SPRINKLES. HOWEVER BY THEN H8
TEMPS WILL HAVE MODERATED SOMEWHAT AND THE UPPER TROUGH AXIS WILL
HAVE MOVED A LITTLE FURTHER NE AND AWAY FROM OUR REGION. THEREFORE
MOST OF THE DAY WEDNESDAY SHOULD BE DRY.

MAX TEMPS TUESDAY AND WEDNESDAY WILL ONLY REACH THE 60S TO NEAR 70
DEGREES WITH MIN TEMPS MAINLY IN THE 50 TO 55 DEGREE RANGE...
ALTHOUGH SOME ISOLATED LOW TEMP READINGS IN THE UPPER 40S ARE
POSSIBLE ACROSS OUR NORTHERN FCST AREA BOTH NIGHTS.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 330 PM EDT MON AUG 24 2015

LONG TERM PERIOD BEGINS WITH THE UPPER TROUGH LIFTING OUT TO THE
NORTHEAST ACROSS EASTERN CANADA. SHORTWAVE RIDGING BUILDS IN FOR
THURSDAY NIGHT. DRY WEATHER IS FORECAST BOTH THURSDAY AND THURSDAY
NIGHT AS A SURFACE HIGH SLIDES ACROSS THE GREAT LAKES.

THE FORECAST BECOMES A BIT MORE UNCERTAIN IN THE FRIDAY TO SATURDAY
TIME FRAME AS THE MODELS ARE FORECASTING A WEAK SHORTWAVE TO CREST
AN UPPER RIDGE IN THE WEST AND MOVE OUR WAY. THE SHORTWAVE IS
HANDLED DIFFERENTLY BY THE OPERATIONAL GFS AND ECMWF. THE ECMWF IS
WEAKER AND A BIT FURTHER SOUTH. FOR NOW...HAVE MATCHED NEIGHBORS
WITH SOME VERY LOW POPS...20-30 PCT FRIDAY NIGHT THROUGH SATURDAY
NIGHT. CONFIDENCE IS LOW THROUGH THESE FORECAST PERIODS THOUGH AS
ITS A FAIRLY WEAK WAVE...AND ITS OUT TOWARD DAY 6 IN THE FORECAST.

HAVE A DRY FORECAST THEREAFTER FROM SUNDAY INTO MONDAY....AS UPPER
RIDGING BEGINS TO TAKE HOLD. TEMPERATURES THROUGH THE LONG TERM LOOK
TO MODERATE...FROM THE UPPER 70S INTO THE 80S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 856 PM EDT MON AUG 24 2015

VFR CONDITIONS EXPECTED THROUGH TUESDAY AFTERNOON ALTHOUGH THERE
MAY BE CEILINGS IN THE 2500 TO 3000 FOOT AGL RANGE AT TIMES
TUESDAY MORNING ALONG WITH SCATTERED SHOWERS. WINDS WILL BE WEST
TO NORTHWEST AROUND 10 KNOTS WITH OCCASIONAL GUSTS TO NEAR 20
KNOTS TIMES ON TUESDAY.

&&

.MARINE...
ISSUED AT 330 PM EDT MON AUG 24 2015

WEST WINDS TO 30 KNOTS WILL CONTINUE TO PRODUCE WAVE HEIGHTS IN
THE 5 TO 8 FOOT RANGE LATE THIS AFTERNOON AND EARLY EVENING. WIND
SPEEDS WILL DIMINISH SOMEWHAT TONIGHT BUT WAVE HEIGHTS WILL STAY
UP IN THE 4 TO 7 FOOT RANGE. CONTINUED NW WINDS AND COLD AIR
ADVECTION WILL RESULT IN WAVE HEIGHTS STAYING UP IN THE 3 TO 6
FOOT RANGE TUESDAY. WAVE HEIGHTS WILL FINALLY SUBSIDE TO BELOW
SMALL CRAFT CRITERIA TUESDAY NIGHT.


&&

.HYDROLOGY...
ISSUED AT 1226 PM EDT MON AUG 24 2015

SCATTERED SHOWERS ARE POSSIBLE THIS AFTERNOON THROUGH
TONIGHT...BUT THE BEST COVERAGE WILL BE TUESDAY-TUESDAY NIGHT. NO
SIGNIFICANT HYDRO IMPACTS EXPECTED FROM THIS RAINFALL. DRY WEATHER
WILL PREVAIL TOWARD THE END OF THE WEEK WITH HIGH PRESSURE IN
PLACE.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH TUESDAY EVENING FOR MIZ037-043-
     050-056-064-071.

LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR LMZ844>849.

&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...OSTUNO
HYDROLOGY...EBW
MARINE...LAURENS



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