FXUS63 KGRR 040550
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1250 AM EST FRI DEC 4 2009

LATEST UPDATE...AVIATION...

.SYNOPSIS...(1056 PM EST THU DEC 3 2009)
LOW PRESSURE WILL MOVE ACROSS LOWER MICHIGAN TONIGHT AND COMBINE 
WITH COLDER AIR MOVING ACROSS LAKE MICHIGAN TO BRING THE FIRST 
SNOWSTORM OF THE SEASON TO SOUTHWEST LOWER MICHIGAN. FROM 4 TO 
LOCALLY 9 INCHES OF SNOW WILL BE POSSIBLE FROM HOLLAND TO MUSKEGON 
AND OVER TO GRAND RAPIDS...WITH LANSING AND JACKSON GETTING LESSER 
AMOUNTS. THE LOW WILL PULL EAST ON FRIDAY BUT LAKE EFFECT SNOW 
SHOWERS WILL CONTINUE INTO THE WEEKEND.

&&

.SHORT TERM...(1056 PM EST THU DEC 3 2009)
(TONIGHT THROUGH SATURDAY NIGHT)
WE HAVE GONE AHEAD AND ISSUED ANOTHER UPDATE TO THE FCST...THIS TIME 
TO UPGRADE THE ADVISORY FOR OTTAWA...KENT...AND MUSKEGON COUNTIES. 
WE ALSO ADDED NEWAYGO TO THE ADVISORY. 

WE RECEIVED A FEW REPORTS OF 5 INCHES THIS EVENING FROM NORTHERN 
OTTAWA COUNTY AND 4 TO 5 INCHES IN KENT COUNTY...JUST EAST OF THE 
KENT/OTTAWA BORDER. THESE LOCATIONS ONLY NEED AN INCH OR SO TO MEET 
WARNING CRITERIA...WHICH SHOULD BE ATTAINABLE AS THE BAND SHIFTS 
SOUTH LATER TONIGHT. THIS BAND IS STILL EXPECTED TO INCH UP INTO 
SOUTHERN MUSKEGON COUNTY AND COULD DO THE SAME DAMAGE AS IT DID IN 
OTTAWA COUNTY. 

THE BEST LIFT WILL BE MOVING EAST WITH THE VORT MAX BY 12Z FRIDAY 
BUT LES SHOWERS WILL CONTINUE THROUGH THE DAY AS MOISTURE AND 
INVERSION REMAIN DEEP. ROADS SHOULD IMPROVE IN THE AFTERNOON AS AIR 
TEMPS RISE TO THE LOWER 30S. ABOVE FREEZING SKIN TEMPS SHOULD ALSO 
TEND TO LIMIT ACCUMS DURING THE DAY FRIDAY DESPITE INVERSION HEIGHTS 
REMAINING AROUND 8 TO 10 KFT.

INVERSION SLOWLY COMES DOWN FRIDAY NIGHT AND SATURDAY MORNING AS 
UPPER TROUGH FLATTENS AND SFC RIDGING BUILDS IN BY SATURDAY NIGHT. 

&&

.LONG TERM...(355 PM EST THU DEC 3 2009)
(SUNDAY THROUGH THURSDAY)
THE PRIMARY FORECAST CHALLENGE IS DEALING WITH THE TIMING... 
LOCATION AND OCCURRENCE OF SNOW FALL. THE MID RANGE MODELS HAVE 
LARGE DIFFERENCES AND CONFIDENCE IS LOW. MAIN CHANGE TO GRIDS WAS TO 
DECREASE POPS MONDAY NIGHT... AS HIGH PRESSURE RIDGES IN AND A BREAK 
MAY OCCUR. OVERALL... POPS BROAD BRUSHED LATE SUNDAY NIGHT THROUGH 
THURSDAY WITH AT LEAST 7/10THS CLOUD COVER. 

A STRONG LOW PRESSURE SYSTEM WILL MOVE THROUGH THE CENTER OF THE 
COUNTRY AROUND WEDNESDAY. THE 12Z ECMWF TAKES THE LOW OVER THE 
FORECAST AREA WEDNESDAY AND THE 12Z GFS TAKES IT SOUTHEAST OF 
TOLEDO. WITH NO WARMING EXPECTED OVER THE AREA... THIS SYSTEM COULD 
BRING A LOT OF SNOW WITH EITHER TRACK. HOWEVER CLIMATOLOGICALLY... 
OUR FORECAST AREA WOULD BE CLOSER TO THE SWEET SPOT WITH A TRACK TO 
THE SOUTHEAST OF THE FORECAST AREA. 

LOW TEMPERATURES WILL BE AROUND AVERAGE FOR THIS TIME OF YEAR... 
WHILE HIGHS WILL BE AROUND NORMAL SUNDAY AND MONDAY AND FALL TO 
BELOW NORMAL LEVELS FOR WEDNESDAY AND THURSDAY. NORMALS ARE HIGHS IN 
THE MID 30S AND LOWS IN THE LOWER TO MID 20S.

&&

.AVIATION...(1250 AM EST FRI DEC 4 2009)
SNOW SHOWERS PERSIST INTO THE OVERNIGHT HOURS WITH IFR CONDITIONS 
EXPECTED FOR MKG AND GRR. HEAVIER SNOW SQUALLS MAY CUT VSBYS DOWN TO 
1/2SM OR WORSE...SO WENT WITH TEMPOS THAT FEATURE LIFR CONDITIONS 
FOR MKG AND GRR THROUGH THE EARLY TO MID MORNING HOURS. LAN MAY ALSO 
GET INTO IFR AT TIMES FOR THE SAME GENERAL TIME PERIOD AS THE SNOW 
SHOWERS WILL TEND TO DRIFT BACK TOWARD THE SOUTH WITH TIME. BOTTOM 
LINE...WORST CONDITIONS WILL BE AT GRR AND MKG THROUGHOUT THE 
MORNING.

ELSEWHERE...PRIMARILY MVFR/VFR CONDITIONS ARE ANTICIPATED AS IS THE 
NATURE OF LAKE EFFECT EVENTS. EXCEPT FOR JXN...FEATURED LIGHT SNOW 
SHOWERS DURING THE EARLY AFTERNOON HOURS WITH THE TREND FOR DRIER 
CONDITIONS EXPECTED. ALL SITES SHOULD BE FREE OF IFR CONDITIONS 
AFTER 18Z...BUT WILL MONITOR CLOSELY. WITH A MORE WSW TO SW FLOW 
DURING THE AFTERNOON...WOULD EXPECT REMAINING SNOW SHOWERS TO BE 
PRIMARILY CONFINED TO THE MKG TERMINAL. 

&&

.MARINE...(334 PM EST THU DEC 3 2009)
EXTENDED THE SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT AS WINDS AND 
WAVES REMAIN HIGH...BUT BELOW GALES.
&&

.HYDROLOGY...(334 PM EST THU DEC 3 2009)
NO HYDRO ISSUES THROUGH AT LEAST EARLY NEXT WEEK AS PRECIP WILL BE 
SNOW AND ANY RUNOFF WILL BE MINIMAL. 

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING FOR MUSKEGON...KENT...AND OTTAWA COUNTIES 
THROUGH FRIDAY AFTERNOON.
WINTER WEATHER ADVISORY FOR NEWAYGO AND ALLEGAN COUNTIES 
THROUGH FRIDAY AFTERNOON.
LM...SMALL CRAFT ADVISORY ST. JOSEPH TO MANISTEE THROUGH FRIDAY 
NIGHT.

&&

$$

SYNOPSIS:     OSTUNO/NJJ
SHORT TERM:   OSTUNO/NJJ
LONG TERM:    IOD
AVIATION:     HOVING
MARINE:       OSTUNO
HYDROLOGY:    OSTUNO