FXUS63 KAPX 291123
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
623 AM EST SUN NOV 29 2009

.SYNOPSIS.../ISSUED AT 515 AM/

WEAK LOW PRESSURE DEVELOPING ACROSS THE REGION TODAY WILL BRING A 
WINTRY MIX OF LIGHT PRECIPITATION TO NORTHERN MICHIGAN. BEHIND THIS 
SYSTEM...TEMPERATURES WILL AVERAGE CLOSER TO WHAT IS TYPICALLY 
EXPECTED FOR THIS TIME OF YEAR. THIS WILL RESULT IN INCREASING 
PROBABILITIES FOR ACCUMULATING LAKE EFFECT SNOW...WITH THE FIRST 
EVENT BEGINNING TONIGHT...AND LASTING THROUGH MONDAY NIGHT. AFTER A 
BRIEF BREAK IN THE ACTION TUESDAY...ANOTHER SHOT OF COLD AIR WILL 
BRING ADDITIONAL SNOW CHANCES TO ROUND OUT THE WORK WEEK.

MSB

&&

.SHORT TERM.../ISSUED AT 515 AM/...TODAY

ILL DEFINED SFC TROUGH SLOWLY SAGGING SOUTHWARD THROUGH THE CWA THIS 
EARLY MORNING. LOW LEVEL MOISTURE...WARMING AND PERIODIC DRIZZLE HAS 
OCCURRED ALONG THIS TROUGH. SHALLOW COLDER AIR BEHIND THE TROUGH
WAS ALLOWING OVERCAST SKIES TO EXPAND SOUTHWARD...BUT STILL HAS
NOT COVERED ALL AREAS NORTH OF THE FRONT. THE SLOW MOVEMENT OF THE
SFC TROUGH HAS RESULTED IN SE COMMUNITIES CLOSER TO THE SAGINAW
BAY TO STAY BASICALLY CLOUD FREE...WITH THE EXCEPTION OF SOME
HIGHER LEVEL CIRRUS. THIS IS RESULTING IN A WIDE ARRAY OF
TEMPERATURES RANGING FROM MID/UPPER 20S IN CLEARER SKIES...TO AS
"WARM" AS THE LOWER 40S IN THE CLOUDS/DRIZZLE ASSOCIATED WITH THE
TROUGH.

UPSTREAM IN MN AND NW WI...LIGHT SNOW BROKE OUT LATE LAST
EVENING...AND HAS BEEN SPREADING EASTWARD TOWARD EASTERN UPPER
OVERNIGHT...WITHIN DPVA AHEAD OF NRN PLAINS SHORTWAVE AND UPPER
DIVERGENCE REGIME IN RIGHT ENTRANCE REGION OF 100KT NRN STREAM
JET. DEEPER LOWER/MID LEVEL MOISTURE REMAINS DETACHED FROM THIS
UPPER LEVEL FORCING...FROM KANSAS AND MISSOURI SOUTHWARD. THIS
MOISTURE WAS STARTING TO SHIFT ENE...PULLED BY WEAKISH H8 WINDS
AHEAD OF WEAK SFC LOW IN NRN IL.

SHORTWAVE LIFTS INTO THE WESTERN GREAT LAKES TODAY. DURING THE 
MORNING...THE DEEPER LOW/MID LEVEL MOISTURE REMAINS DETACHED FROM 
THE UPPER DYNAMICS...WHICH SPREAD IN ACROSS EASTERN UPPER. BASED
ON MODEL SOUNDINGS/VARIOUS CRITICAL THICKNESSES...TEMPERATURES
WILL BE COOL ENOUGH FOR SNOW AT PRECIPITATION ONSET...WITH NO
APPARENT MIX OF RAIN. THE LACK OF OVERALL MOISTURE WILL CERTAINLY
LIMIT SNOWFALL...AS WILL LOW SNOWFALL RATES. AROUND AN INCH IS MORE
THAN REASONABLE. MAYBE A FEW SPOTS NEAR 2 INCHES ACROSS WESTERN
AREAS OF CHIP/MACK WHERE THE SNOW WILL BE SLIGHTLY ENHANCED BY
NNW FLOW OF H8 AIR TEMPS APPROACHING -6C. 

TO THE SOUTH...PRECIPITATION OUGHT TO START NEAR THE NOON
HOUR...WHILE BETTER LOW LEVEL MOISTURE IS EXPECTED TO START
WORKING IN CONJUNCTION WITH THE UPPER SUPPORT INTO THE AFTERNOON.
THUS...PRECIPITATION IS EXPECTED TO EXPAND OVER LOWER MICHIGAN.
THERMAL PROFILES SUGGEST AN ALL LIQUID ONSET...CHANGING OVER TO
SNOW FROM NW TO SE INTO THE AFTERNOON. IT NEVER REALLY GETS COLD
ENOUGH FOR SNOW ACROSS THE FAR SE CWA...WHILE THE COASTAL
LOCATIONS FROM GTV BAY SOUTH SHOULD REMAIN A MIX OF RAIN/SNOW.
SNOW TOTALS HERE WILL BE MINIMAL...MAYBE A HALF INCH ON THE HIGHER
TERRAIN/INLAND AREAS OF FAR NRN LOWER. SMD

&&

.LONG TERM.../ISSUED AT 515 AM/...TONIGHT AND BEYOND

TONIGHT...UPPER FORCING WITH SHORTWAVE LIFTS EAST WITH WEAK SFC
LOW. H8 TEMPS DROP INTO THE -7C TO -10C RANGE...AND LES WILL BE
OCCURRING. HOWEVER...MOISTURE IS RATHER UNIMPRESSIVE NOW...AND
INVERSION HEIGHTS REALLY ONLY AROUND 4-4.5 KFT OR SO. LOW LEVEL
RIDGING BEHIND THE DEPARTING SFC LOW WILL ALSO PRODUCE AN
UNFAVORABLE ANTICYCLONIC FLOW FOR A BIT. THUS...EXPECTING ANY LES
TO BE RATHER DISORGANIZED. ONLY MINOR ACCUMULATIONS...AROUND AN
INCH.

MONDAY AND MONDAY NIGHT...SHEARED OUT SHORTWAVE DIVES INTO THE
BACKSIDE OF LONGER WAVE TROUGH. MODELS LOOK TOO AGGRESSIVE WITH
PRECIP ON THIS FEATURE...BUT AM EXPECTING ONGOING LES TO GET
ENHANCED TO SOME DEGREE. THIS IS A REALLY TOUGH FORECAST...AS
LOW LEVEL WINDS WILL SHIFTING QUITE A BIT...FROM NW TO WSW AHEAD
OF APPROACHING WAVE...THEN BACK TO WNW WITH IT'S PASSAGE. THROW IN
SLIGHT WARMING OF THE H8 TEMPS...RESULTING IN MORE MARGINAL DELTA
T'S...AND THE FACT THAT COASTAL LOCATIONS WILL LIKELY GO BACK TO A
MIX OF RAIN AND SNOW...AND YOU GET...WELL A BUNCH TO THINK ABOUT.
WILL NOT GO ANY HIGHER THAN AN INCH FOR MOST PLACES ATTM. WILL TRY
TO SORT OUT THE FINER DETAILS OVER THE NEXT COUPLE OF FORECAST
ISSUANCES. LES WILL BE STRONGEST LATER MONDAY AFTERNOON/MONDAY
EVENING...AND AS IT STANDS NOW...WOULD EXPECT HIGHEST ACCUMS
ACROSS THE PELLSTON AREA DURING THIS TIME FRAME. 

TUESDAY AND LATER PERIODS...LES WILL LINGER INTO TUESDAY AS WINDS
SHIFT SW AHEAD OF A STRENGTHENING CLIPPER SYSTEM THAT WILL PASS
THROUGH ONTARIO. THIS SYSTEM MAY TRY AND DROP A TOUCH OF SYSTEM
LIGHT SNOW ACROSS EASTERN UPPER...BUT LES WILL SHUT OFF BY TUESDAY
NIGHT WITH EXPECTED STRONG LOW LEVEL WARMING. SFC COLD FRONT
SWEEPS THROUGH LATE TUESDAY NIGHT...BUT IT WILL TAKE UNTIL
WEDNESDAY AFTERNOON AND EVENING BEFORE THE AIR MASS GETS COLD
ENOUGH FOR LES PRODUCTION. LOTS OF UNCERTAINTY IN THE EXTENDED
REGARDING THE EVOLUTION OF THE NRN/SRN JET STREAMS AND THEIR
ASSOCIATED LOW LEVEL PRESSURE FIELDS. KINDA LOOKS LIKE THAT
POTENTIALLY SIGNIFICANT LES PERIOD WED NIGHT-FRIDAY NIGHT...IS
LESS OF A THREAT NOW. STAY TUNED. SMD

&&

.MARINE.../ISSUED AT 515 AM/

SLOW MOVING FRONT DROPPING SOUTH ACROSS THE REGION WILL MAKE WAY
FOR MORE BRISK NORTHERLY WINDS LATER THIS AFTERNOON INTO TONIGHT
DUE TO GROWING INSTABILITY OVER THE LAKES. WINDS IN MOST AREAS
WILL REMAIN JUST BELOW SMALL CRAFT ADVISORY LEVELS...BUT COASTAL
CONVERGENCE/FUNNELING REGIMES WILL NECESSITATE THE ISSUANCE OF
VARIOUS ADVISORIES. MANITOU PASSAGE AND PRESQUE ISLE TO STURGEON
POINT ARE THE MAIN AREAS WHERE GUSTS ARE EXPECTED TO EXCEED 25
KNOTS. IT WILL REMAIN GUSTY MONDAY AND MONDAY NIGHT...BUT WINDS
WILL MAINLY HOLD IN THE 10-20 KT RANGE...FOR THE MOST PART.
AGAIN...THERE WILL LIKELY BE A FEW PLACES THAT WILL NEED
ADVISORIES. SMD

&&

.AVIATION.../ISSUED AT 620 AM/...VALID FOR 12Z TAFS

LOW PRESSURE TRACKS ACROSS LOWER MICHIGAN TODAY RESULTING IN
CONTINUED PREVAILING MVFR CIGS...AS WELL AS THE DEVELOPMENT OF A
LIGHT RAIN AND SNOW MIX. THIS WINTRY MIX WILL DEVELOP 15-18Z AND
SLOWLY CHANGE OVER TO SNOW/LAKE EFFECT SNOW LATER INTO THIS 
AFTERNOON AND EVENING. THIS SNOW WILL BRING PERIODIC IFR VSBYS
THROUGH THE TAF PERIOD. 

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 6 AM EST MONDAY 
     FOR LMZ323-342-344>346.
LH...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 6 AM EST MONDAY 
     FOR LHZ348-349.
LS...NONE.

&&

$$