000
FXUS63 KGRR 301656
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1200 PM EST SAT NOV 30 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 337 AM EST SAT NOV 30 2013

A WEAK COLD FRONT WILL DROP SOUTH THROUGH LOWER MICHIGAN TONIGHT
LEADING TO A CHANCE OF LIGHT SNOW. OTHERWISE...MAINLY DRY WEATHER IS
EXPECTED THROUGH MONDAY. A LARGER STORM SYSTEM MIDWEEK WILL BRING
MIXED RAIN AND SNOW BEFORE COLDER AIR MOVES IN TOWARD THE END OF THE
WEEK.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 337 AM EST SAT NOV 30 2013

FORECAST CONCERNS ARE MINIMAL TODAY. THE MAIN FOCUS IS A COLD FRONT
DROPPING SOUTH TONIGHT AS A CLIPPER MOVES BY TO THE NORTH. GUIDANCE
IS PRETTY DRY WITH THIS SYSTEM. LOOKING AT REGIONAL RADAR OVER THE
NORTH CENTRAL US CONDITIONS ARE MOSTLY DRY. SO CAN/T SEE MUCH MORE
THAN A SLIGHT CHANCE OF LIGHT SNOW ACROSS MAINLY THE NORTHEAST CWA
TONIGHT. WE/LL SEE HIGHS IN THE MID TO UPPER 30S THROUGH MONDAY.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 337 AM EST SAT NOV 30 2013

HAVE OPTED TO FOLLOW THE ECMWF GUIDANCE TONIGHT VS THE GFS AS IT
SEEMS TO HANDLE THE DEVELOPMENT OF THE WESTERN TROUGH BETTER
(DIGGING/SLOWER). THIS HAS RAMIFICATIONS ON THE SENSIBLE WEATHER AS
WE HEAD INTO NEXT WEEK. THE GFS EJECTS SOME ENERGY OUT OF THE
WESTERN TROUGH QUICKER AND LEADS TO DOWNSTREAM CYCLOGENESIS EARLIER
THAT WHAT SHOULD BE LIKELY. THE GFS IS PUSHING A LOW IN THE WESTERN
GREAT LAKES TUESDAY EVENING...WHEREAS THE ECMWF HOLDS THE LOW OFF BY
ABOUT 24 HOURS.

SO...BASED ON THE ECMWF...EXPECT ANY PRECIPITATION MONDAY NIGHT
THROUGH WEDNESDAY TO BE LIGHT...IF NOT ENTIRELY DRY. MONDAY NIGHT IT
DOES LOOK LIKE THERE MAY BE SOME LIGHT OVERRUNNING SNOW ACROSS LOWER
MICHIGAN AND HAVE THIS COVERED WITH 20-30 PCT POPS FOR NOW.

MAIN BATCH OF PRECIPITATION SHOULD HOLD OFF UNTIL WEDNESDAY NIGHT
INTO THURSDAY WITH THE LOW PUSHING A COLD FRONT THROUGH THE AREA.
EXPECTING RAIN FOR THE MOST PART AS WARM AIR SURGES NORTH INTO THE
GREAT LAKES. BY 18Z WED...THE EURO HAS +2 TO +4 AIR AT 850MB/S
SURGING NORTH INTO THE REGION. THE +8 ISOTHERM MAKES IT INTO THE FAR
SOUTHERN CWA WEDNESDAY NIGHT.

COLDER AIR WRAPS IN FROM THE WEST BEGINNING THURSDAY AFTERNOON.
COULD SEE SOME LINGERING RAIN/SNOW THURSDAY NIGHT BEHIND THE
DEPARTING FRONT. FRIDAY SEEMS LIKE WE WILL BE MOVING INTO A LAKE
EFFECT SCENARIO WITH 850MB AIR PLUNGING INTO THE NEGATIVE TEENS C.
MOISTURE IS SOMEWHAT OF A QUESTION...BUT THE UPPER TROUGH OVERHEAD
WOULD INDICATE WE SHOULD HAVE THE MOISTURE. BUMPED UP POPS FOR
FRIDAY AND EXPANDED CHANCES FOR SNOW SHOWERS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1200 PM EST SAT NOV 30 2013

VFR CONDITIONS TO CONTINUE THIS AFTERNOON AND EVENING. CONDITIONS
WILL GRADUALLY DETERIORATE TO MVFR LATE TONIGHT AS LOW CLOUDS MOVE
IN. SOME PATCHY FOG AND ALSO VERY LIGHT SNOW SHOWERS AND FLURRIES
ARE EXPECTED DURING THE EARLY TO MID MORNING HOURS SUNDAY.
CONDITIONS SHOULD STAY MAINLY MVFR THROUGH SUNDAY MORNING BEFORE
IMPROVING TO VFR SUNDAY AFTERNOON.

&&

.MARINE...
ISSUED AT 1046 AM EST SAT NOV 30 2013

SOUTHERLY FLOW WILL REMAIN ELEVATED TODAY LEADING TO HIGHER WAVES
AND HAZARDOUS CONDITIONS FOR SMALL CRAFT. WIND SHIFT TONIGHT AS
THE FRONT GOES THROUGH...PROLONGING THE HIGHER WAVES. ON SUNDAY
THE PRESSURE GRADIENT WEAKENS. THIS WILL CAUSE WAVES TO DECREASE
IN HEIGHT.

&&

.HYDROLOGY...
ISSUED AT 337 AM EST SAT NOV 30 2013

NO CHANGE TO THE FLOOD WATCH FOR MECOSTA COUNTY. THE ICE JAM ON THE
MUSKEGON RIVER ABOVE ROGERS DAM LIKELY WON/T CHANGE TOO MUCH OVER
THE NEXT DAY OR TWO GIVEN HIGHS ABOVE FREEZING AND LOWS BELOW
FREEZING.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FLOOD WATCH UNTIL 7 PM EST THIS EVENING FOR MIZ045.

LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST SUNDAY FOR LMZ845>849.

&&

$$

SYNOPSIS...93
SHORT TERM...93
LONG TERM...DUKE
AVIATION...LAURENS
HYDROLOGY...93
MARINE...MJS