Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 051930
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 PM EDT THU MAY 5 2016

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

.SYNOPSIS...
ISSUED AT 330 PM EDT THU MAY 5 2016

MAINLY CLEAR AND COOL CONDITIONS ARE EXPECTED TONIGHT WITH LOWS
DIPPING INTO THE MID 30S ACROSS CENTRAL LOWER AND AROUND 40
ELSEWHERE. A SOUTHERLY FLOW OF AIR AHEAD OF A COLD FRONT WILL BOOST
TEMPERATURES ON FRIDAY TO ABOVE NORMAL VALUES OF AROUND 70 DEGREES.
THE COLD FRONT WILL MOVE INTO THE REGION FRIDAY NIGHT AND PASS SOUTH
OF THE AREA ON SATURDAY. SHOWERS AND THUNDERSTORMS WILL ACCOMPANY
THE FRONT THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. THE RAIN WILL
MOVE OUT OF THE AREA BY SATURDAY EVENING WITH COOLER AIR FILTERING
IN BEHIND IT. HIGHS ON SUNDAY WILL TOP OUT IN THE LOW TO MID 60S.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM EDT THU MAY 5 2016

MAIN CONCERNS IN THE SHORT TERM PERTAIN TO CHANCES FOR SHOWERS AND
STORMS WITH THE FRONTAL PASSAGE FRIDAY NIGHT AND SATURDAY.
OTHERWISE...THE FORECAST IS STRAIGHT FORWARD.

INSTABILITY IS NOT GREAT WITH THE FRONT FRIDAY NIGHT AND SATURDAY.
CAPE VALUES ARE GENERALLY 500 J/KG OR LESS THROUGH THIS TIME FRAME.
THE EXCEPTION IS SATURDAY AFTERNOON IN THE SOUTHEAST CWA TOWARDS
JACKSON. IT APPEARS THE AIR MASS MAY RECOVER ENOUGH TO PRODUCE CAPE
VALUES NEAR 1000 J/KG. THE NAM INDICATES CAPE AS HIGH AS 1800 J/KG
ACROSS JACKSON COUNTY AT 18Z. BOTTOM LINE...EXPECTING A BAND OF
SHOWERS TO PROGRESS SOUTHEAST THROUGH THE FORECAST AREA FRIDAY NIGHT
AND SATURDAY WITH SOME ISOLATED EMBEDDED STORMS. THE BEST CHANCES
WILL BE SATURDAY AFTERNOON ALONG AND AHEAD OF THE FRONT IN THE
SOUTHEAST HALF OF THE FORECAST AREA.

OTHERWISE...PRETTY QUIET WEATHER IN THE REMAINDER OF THE SHORT TERM.
WE MAY HAVE SOME PATCHY FROST ACROSS CENTRAL LOWER MICHIGAN TONIGHT.
OTHERWISE...MOSTLY CLEAR TO PARTLY CLOUDY SKIES TONIGHT...FRIDAY
AND AGAIN SATURDAY NIGHT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 330 PM EDT THU MAY 5 2016

A WEAK HIGH PRESSURE RIDGE WILL BRING FAIR WX WITH SEASONABLE TEMPS
SUNDAY THROUGH SUNDAY NIGHT.  A WARM FRONT WILL LIFT SLOWLY NORTH
INTO THE LOWER GREAT LAKES REGION EARLY NEXT WEEK. ISENTROPIC
UPGLIDE NORTH OF THE FRONT WILL RESULT IN SCATTERED RAIN SHOWER
DEVELOPMENT AS EARLY AS MONDAY.

THERE IS POTENTIAL FOR MORE WIDESPREAD RAIN AND PERHAPS A FEW
THUNDERSTORMS MONDAY NIGHT THROUGH TUESDAY NIGHT AS LOW PRESSURE
MOVES EAST ALONG THE BOUNDARY. A FEW SHOWERS MAY LINGER INTO
MIDWEEK.

LARGER MEDIUM RANGE GUIDANCE DISCREPANCIES RESULT IN A LOWER
CONFIDENCE FORECAST FOR LATE IN THE WEEK. 12Z GFS/CANADIAN GUIDANCE
SUGGESTS A RIDGE OF HIGH PRESSURE WILL BUILD IN TO PRODUCE FAIR WX
LATE WEDNESDAY THROUGH THURSDAY.

CONVERSELY THE 12Z ECMWF SUGGESTS A WET WX PATTERN WOULD CONTINUE AS
ANOTHER LOW PRESSURE SYSTEM MOVES IN TO BRING RAIN WEDNESDAY NIGHT
THROUGH LATE IN THE WEEK. SO AT THIS TIME WE WILL GO WITH LOW CHC
POPS FOR SHOWERS LATE NEXT WEEK. TEMPERATURES WILL AVERAGE RATHER
CLOSE TO NORMAL THROUGH THE LONG RANGE FCST PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 224 PM EDT THU MAY 5 2016

VFR CONDITIONS WILL CONTINUE AT ALL THE TERMINALS THROUGH 18Z
FRIDAY. SCT FAIR WX CU THIS AFTERNOON WILL DISSIPATE THIS EVENING
WITH MOSTLY CLEAR SKIES TO FOLLOW OVERNIGHT THRU MIDDAY FRIDAY. NW
WINDS AROUND 10-15 KTS THIS AFTERNOON WILL BECOME CALM OVERNIGHT
BEFORE BECOMING SE AT AROUND 5 TO 10 KTS BY LATE FRIDAY MORNING.


&&

.MARINE...
ISSUED AT 330 PM EDT THU MAY 5 2016

WINDS AND WAVES ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA THROUGH FRIDAY NIGHT. THIS AFTERNOON AND EARLY EVENING
HOWEVER...WINDS AND WAVES WILL BE APPROACH SCA CRITERIA FROM
MUSKEGON SOUTH DOWN THE SHORE. THIS WILL BE SHORT LIVED AND WILL BE
BORDERLINE...2-4 FEET...SO NO HEADLINE WILL BE ISSUED.

THE NEXT HEADLINE POTENTIAL COMES INTO PLACE ON SATURDAY AS
NORTHERLY WINDS RAMP UP BEHIND A COLD FRONT. NORTH WINDS TO 30 KNOTS
LOOK LIKELY WITH THE POSSIBILITY OF GALES. IT APPEARS TO BE ANOTHER
CLOSE CALL ON GALES. THE SOUTHERN THREE NEARSHORE ZONES...OR FROM
GRAND HAVEN SOUTHWARD...WILL BE THE AREAS WITH THE HIGHEST WINDS AND
WAVES ON SATURDAY.

&&

.HYDROLOGY...
ISSUED AT 1116 AM EDT THU MAY 5 2016

RIVER FLOOD ADVISORIES ARE CURRENTLY POSTED FOR THE GRAND RIVER AT
IONIA... THE THORNAPPLE RIVER IN HASTINGS AND THE MAPLE RIVER IN
MAPLE RAPIDS. ALL RIVER LEVELS AT THESE SITES ARE RISING. THEY ARE
AT OR JUST ABOVE BANKFULL LEVELS AND SHOULD CREST THURSDAY OR FRIDAY
BELOW FLOOD STAGE. A FEW OTHER SITES ARE FORECAST TO CREST BY THE
WEEKEND. RAINFALL THIS WEEKEND MAY SLOW THE FALL OF LEVELS... BUT
THEY SHOULD CONTINUE TO FALL.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...63
MARINE...DUKE



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