Winter Storm in Michigan, December 1 to 2, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1215 PM EST SAT DEC 1 2007

LATEST UPDATE...AVIATION...

.SYNOPSIS...(435 AM EST SAT DEC 1 2007)
A WINTER STORM WILL IMPACT THE REGION STARTING LATE THIS AFTERNOON
AND CONTINUE INTO SUNDAY MORNING.  SNOW WILL DEVELOP BY LATE
AFTERNOON...THEN IT WILL CHANGE OVER TO MIXED SLEET AND FREEZING
AROUND MIDNIGHT.  THEN FINALLY THE PRECIPITATION WILL CHANGE OVER TO
ALL RAIN EARLY SUNDAY MORNING.  THE MESSY MIX WILL RESULT IN
SIGNIFICANT TRAVEL ISSUES INTO EARLY SUNDAY.

COLDER AIR RETURNS SUNDAY NIGHT AND MONDAY AS THE STORM SYSTEM
DEPARTS.  SOME LIGHT LAKE ENHANCED SNOWFALL CAN BE EXPECTED ALONG
WITH BRISK WINDS.

&&

.SHORT TERM...(1130 AM EST SAT DEC 1 2007)
UPDATED NDFD WX/POP/QPF/SNOW GRIDS TO FINE TUNE TIMING OF PCPN
DEVELOPMENT AND AMOUNTS ACROSS OUR CWFA DURING THE MID TO LATE AFTN
HOURS. CURRENT WINTER STORM WARNING AND WINTER WX ADVISORY HEADLINES
LOOK REASONABLE AND NO CHANGES TO THOSE ARE PLANNED ATTM. LATEST
GUIDANCE AND TRENDS SEEM TO SUGGEST THAT OUR SOUTHERN CWFA (SOUTH OF
I-96) WILL NOT GET MUCH SNOW (MOST LIKELY AROUND AN INCH OR LESS)
LATE THIS AFTN AND EARLY EVENING. THIS AS A RESULT OF A FASTER
TRANSITION TO SLEET AND FZRA SOUTH DURING THE EVENING HOURS.

WE WILL REVIEW ALL LATEST 12Z GUIDANCE AND MODEL TRENDS THOROUGHLY
AND THEN MAKE ANY NECESSARY TWEAKS/FCST MODIFICATIONS WITH THE AFTN
FCST PACKAGE.

&&

.LONG TERM...(435 AM EST SAT DEC 1 2007)
THE MAIN STORY IN THE EXTENDED PERIOD IS THAT WELL REMAIN IN THE
COLD AIR MOST OF THE COMING WEEK. WHATS A LITTLE MORE PROBLEMATIC
IS THE POTENTIAL FOR SNOW SHOWERS EACH DAY.

ON TUESDAY THE POTENTIAL FOR LAKE EFFECT DOES NOT LOOK ALL THAT
GREAT SINCE LOW LEVEL FLOW IS PROGGED TO WEAK/DIVERGENT AND
INCREASING ANTICYCLONIC AS SURFACE RIDGING NOSES IN FROM THE NW.
WILL ONLY CARRY A CHANCE IN THE LAKESHORE COUNTIES.

THE POTENTIAL FOR A SYNOPTIC CLIPPER TYPE SYSTEM DOES NOT LOOK AS
GREAT IN LATEST 00Z OPERATIONAL RUNS... BUT STILL CANT BE RULED OUT
TUESDAY NIGHT INTO WEDNESDAY. IF SYSTEM PASSES BY TO THE SOUTH...
THE LOW LEVEL FLOW WOULD BE EASTERLY WITH NO LAKE EFFECT IN SW MI.

HEADING INTO THURSDAY...SURFACE HIGH IS PROGGED TO SLIDE BY TO OUR
SOUTH. THIS WOULD LEAD TO FAVORABLE WINDS FOR LAKE EFFECT... BUT
ANTICYCLONIC FLOW WOULD LIKELY MEAN ONLY RELATIVELY LIGHT ACTIVITY.
TEMPS SHOULD MODERATE A BIT TOWARD THE END OF THE WEEK AS THE HIGH
WORKS TOWARD THE EAST COAST.
&&

.AVIATION...(1215 PM EST SAT DEC 1 2007)
VFR CONDITIONS THROUGH 20-22Z FOLLOWED BY THE ARRIVAL OF A BAND OF
SNOW FROM THE WSW WHICH WILL RAPIDLY SEND TAF SITES DOWN TO IFR OR
LOWER CONDITIONS LATE THIS AFTN AND EARLY EVENING. PRECIPITATION
WILL GRADUALLY CHANGE TO SLEET FOR SEVERAL HOURS THIS EVENING
FOLLOWED BY SEVERAL HOURS OF FREZING RAIN. ALL THIS WILL OBVIOUSLY
POSE A SIGNIFICANT HAZARD TO ALL AVIATION INTERESTS FROM LATE THIS
AFTN THROUGH TONIGHT. PCPN WILL GRADUALLY TRANSITION TO RAIN AT THE
AZO... BTL AND JXN SITES BY AROUND 08Z TO 10Z. LIGHT FREEZING RAIN
AND FREEZING DRIZZLE WILL TRANSITION TO RAIN AT GRR... LAN AND MKG
BETWEEN 10Z AND 12Z. IT WILL BECOME WINDY FROM LATE THIS AFTERNOON
THROUGH TONIGHT AND SUNDAY AS WELL.

&&

.MARINE...(1130 AM EST SAT DEC 1 2007)
HAVE OPTED TO UPGRADE TO A GALE WARNING FROM LATE THIS AFTERNOON
THROUGH TONIGHT AND SUNDAY. MODEL GUIDANCE SHOWS GALE FORCE WINDS TO
35 KTS ARE A PRETTY GOOD BET OVER OUR NSH WATERS IN THIS TIME FRAME
AND THIS ALSO MATCHES UP WITH CHICAGO/S GALE WARNING.

&&

.HYDROLOGY...(435 AM EST SAT DEC 1 2007)
SOME AREAS MAY SEE UP TO AN INCH OF QPF.  HOWEVER SINCE IT WILL BE
MIXED PCPN IT WILL NOT ALL GO DIRECTLY INTO THE RIVERS...SO NO HYDRO
CONCERNS ARE ANTICIPATED.
&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI....WINTER STORM WARNING NORTHERN 1/3 CWA LATE THIS AFTERNOON
THROUGH MID DAY SUNDAY.
WINTER STORM WARNING CENTRAL 1/3 CWA LATE THIS AFTERNOON THROUGH
DAYBREAK SUNDAY.
WINTER WEATHER ADVISORY SOUTHERN 1/3 LATE THIS AFTERNOON THROUGH
DAYBREAK SUNDAY.
LM...GALE WARNING ENTIRE NEARSHORE LATE THIS AFTERNOON THROUGH
SUNDAY.

&&

SYNOPSIS:   JK
SHORT TERM: LAURENS
LONG TERM:  MEADE
AVIATION:   LAURENS
MARINE:     LAURENS
HYDROLOGY:  JK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
655 AM EST SAT DEC 1 2007

MIZ037>040-043>046-050>052-056>059-064>067-071>074-021115-
MASON-LAKE-OSCEOLA-CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON-
MONTCALM-GRATIOT-OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON-
INGHAM-VAN BUREN-KALAMAZOO-CALHOUN-JACKSON-
655 AM EST SAT DEC 1 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A SIGNIFICANT WINTER STORM WILL BRING A MIXTURE OF SNOW...SLEET...
AND FREEZING RAIN TO THE REGION LATE THIS AFTERNOON AND TONIGHT.
SNOW AND ICE ACCUMULATIONS ARE LIKELY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

TEMPERATURES WILL WARM ABOVE FREEZING SUNDAY MORNING ENDING THE
THREAT OF FREEZING PRECIPITATION.

SNOW SHOWERS ARE POSSIBLE EACH DAY MONDAY THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SNOW AND ICE MEASUREMENTS WOULD BE HELPFUL TONIGHT. YOU CAN SEND
THEM THROUGH OUR WEATHER SPOTTER REPORT FORM AT:

WWW.WEATHER.GOV/GRR/SPOTTER

LMZ844>849-021115-
ST JOSEPH TO SOUTH HAVEN MI-SOUTH HAVEN TO HOLLAND MI-
HOLLAND TO GRAND HAVEN MI-GRAND HAVEN TO WHITEHALL MI-
WHITEHALL TO PENTWATER MI-PENTWATER TO MANISTEE MI-
655 AM EST SAT DEC 1 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A SIGNIFICANT WINTER STORM WILL BRING A MIXTURE OF SNOW...SLEET...
AND FREEZING RAIN TO THE REGION LATE THIS AFTERNOON AND TONIGHT.
NEAR GALE FORCE SOUTHEAST WINDS CAN BE EXPECTED THIS AFTERNOON AND
TONIGHT AS THE LOW PRESSURE SYSTEM APPROACHES.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

WINDS WILL BECOME NORTHWEST LATE SUNDAY AFTER THE LOW PRESSURE
SYSTEM PASSES BY...CAUSING WAVES TO BUILD TO GREAT THAN 8 FEET.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

MEADE