FXUS63 KAPX 091733
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1233 PM EST WED DEC 9 2009

.SYNOPSIS.../ISSUED AT 357 AM/

A POWERHOUSE OF A STORM SYSTEM WILL LIFT ACROSS LOWER MICHIGAN TODAY 
AND BRING CONTINUED MODERATE TO HEAVY SNOWS TO THE NORTH WOODS. SOME 
OF THIS SNOW WILL MIX WITH OR CHANGE TO RAIN ALONG THE LAKE HURON 
COAST. MODERATE TO HEAVY LAKE EFFECT SNOW AND GUSTY WINDS...WILL 
BECOME A MAJOR INFLUENCE WITHIN THE SNOW BELTS TONIGHT AND 
THURSDAY...AND WILL HELP KEEP SEVERE WINTER WEATHER GOING IN MANY 
AREAS OF NORTHERN MICHIGAN. 

ADDITIONAL LAKE EFFECT SNOWS WITH LIGHTER ACCUMULATIONS WILL 
CONTINUE THURSDAY NIGHT INTO SATURDAY. 

&&

.SHORT TERM.../ISSUED AT 1038 AM/...THIS AFTERNOON THROUGH TONIGHT

PER 15Z SFC ANALYSIS...977 MB LOW PRESSURE CENTER LOCATED OVER BIG 
RAPIDS AND SHARP CONVERGENCE AXIS STRETCHING ENE THROUGH CENTRAL 
LOWER MICHIGAN. 3 HOUR PRESSURE FALLS SUGGEST LOW WILL TRACK FROM 
RQB TO HARRISVILLE OVER THE NEXT SEVERAL HOURS...PRETTY MUCH AS 
ANTICIPATED AND RIGHT BETWEEN THE GFS/NAM SOLUTIONS OF YESTERDAY. 
ALSO AS ANTICIPATED...A COUPLE WAVES OF VERY INTENSE SNOWFALL (WITH 
A FEW CLUSTERS OF THUNDER BETWEEN 10Z AND 12Z) IN THE PROCESS OF 
LIFTING NORTHWARD THROUGH THE CWA...COURTESY OF IMPRESSIVE SURGE OF 
LOW-MID LEVEL ISENTROPIC ASCENT AND UPPER DIVERGENCE BULLSEYE MOVING 
THROUGH. 

MID LEVEL DRY SLOT NOW SKIRTING THE S/SE COUNTIES WITH GLADWIN AND 
ARENAC COUNTIES NEARLY PRECIP FREE AT THIS POINT. ALSO ACROSS THE 
SE...WEDGE OF WARMEST AIR AND SFC TEMPS NEAR 37F LEADING TO A 
RAIN/SNOW MIX REPORTED IN THE LAST FEW HOURS. 

REST OF THE DAY...MAIN FORECAST CONCERN REVOLVES AROUND HEADLINE 
MANAGEMENT AS MAIN PRECIP SHIELD PIVOTS AROUND THE CWA FOLLOWED BY 
DEFORMATION/LAKE EFFECT SNOW SHOWERS SETTING UP LATE THIS AFTERNOON 
AND ESPECIALLY TONIGHT. AS MENTIONED ABOVE...DRY SLOT SKIRTING THE 
SE COUNTIES ALONG WITH A SNOW/RAIN MIX PRETTY MUCH SPELLS THE END OF 
THE WORST CONDITIONS FOR GLADWIN/ARENAC AND POSSIBLY IOSCO COUNTIES. 
WAS ALSO GETTING CONCERNED ABOUT MANISTEE OVER THE ROSCOMMON 
COUNTIES WITH THAT DRY SLOT IMPINGING ON THE CWA. HOWEVER...PRECIP 
HAS BEEN FILLING IN NICELY ALONG AFOREMENTIONED LOW LEVEL CONVERGENCE 
AXIS OVER THE SW COUNTIES...WHICH I ANTICIPATE WILL SLIDE NE FROM 
RQB TO HARRISVILLE (ALONG THE LOW TRACK). ALL THINGS CONSIDERED... 
LOOKS LIKE GREATEST SNOW ACCUMULATIONS TODAY WILL OCCUR NORTH OF A 
LINE FROM CADILLAC TO HARRISVILLE WITH THE GREATEST AMOUNTS NORTH OF 
M-32 INTO EASTERN UPPER MICHIGAN. SO...CAN SAFELY LEAVE WARNINGS 
INTACT FOR THOSE AREAS. 

FOR THE SE COUNTIES...THERE IS ANOTHER BATCH OF SYNOPTIC PRECIP 
EXPANDING ACROSS SRN LOWER MICHIGAN CURRENTLY...WHICH I THINK IS 
ASSOCIATED WITH POCKET OF COLD AIR SWINGING AROUND THE S/SE PART OF 
THE STORM THROUGH SRN LOWER MICHIGAN/OHIO VALLEY...AND THE 
ASSOCIATED FRONTOLYSIS/FRONTOGENETIC FORCING. RADAR TRENDS SUGGEST 
THIS LATEST BATCH OF PRECIP WILL LARGELY MISS THE SE COUNTIES AND 
SINCE DEFORMATION/LAKE EFFECT SNOWS LATER ON WILL ALSO NOT IMPACT 
THAT AREA (AT LEAST MUCH)...WILL LIKELY TRIM OUT GLADWIN/ARENAC AND 
IOSCO COUNTIES FROM THE WARNINGS WITH THE MORNING UPDATE.

WINDS AND BLIZZARD CONCERNS: HAVE HAVE A FEW OBS (NAMELY APN AND 
PLN) REPORT BLIZZARD CONDITIONS (I.E. 1/4SM VSBY IN SNOW/BLSN AND 
WINDS 35 MPH OR GREATER). HOWEVER...TECHNICALLY NOT TRUE BLIZZARD 
CONDITIONS SINCE THOSE CONDITIONS DID NOT PERSIST FOR 3 HOURS. 
SO...COMFORTABLE AT THIS JUNCTURE WITH NOT HAVING OR ISSUING ANY 
BLIZZARD WARNINGS. TONIGHT IS ANOTHER STORY HOWEVER AS WINDS BACK TO 
NW THEN WEST WITH HEAVY LAKE SNOWS IMPACTING EASTERN UPPER AND NW 
LOWER MICHIGAN. WILL NEED TO MULL OVER BLIZZARD HEADLINE 
POSSIBILITIES FOR AT LEAST A PORTION OF NW LOWER MICHIGAN...ALTHOUGH 
HISTORICALLY GETTING TRUE BLIZZARD CONDITIONS OUT OF LAKE EFFECT IS 
A TOUGH THING TO DO JUST DUE TO THE NEEDED PERSISTENCE.

ADAM   

&&

.LONG TERM.../ISSUED AT 357 AM/...TONIGHT AND BEYOND

TONIGHT THROUGH THURSDAY...POWERFUL STORM AND SYSTEM SNOW EXITS EAST 
THIS EVENING...BUT WEAKENING DEFORMATION WILL CONTINUE TO PROVIDE 
SOME ADDITIONAL SYSTEM SNOWS ACROSS THE NE CWA. WINDS WILL BE 
BACKING AROUND TO THE WNW AND WEST...USHERING IN COLDER AND COLDER 
H8 AIR (TEMPS FALLING TO -16C/-17C) WITH GOOD CYCLONIC CONVERGENCE. 
LAKE EFFECT SNOWS WILL BE DEVELOPING IN THE STORM'S WAKE...IF NOT 
ALREADY DEVELOPED OFF LAKE MICHIGAN BY NIGHTFALL. DEEP ATMOSPHERIC 
MOISTURE REMAINS IN PLACE DURING THIS TIME WHILE H8 TEMPS ARE 
PRIME...BUT WINDS NEVER SETTLE IN UNTIL LATE TONIGHT/DAYBREAK 
THURSDAY. AM EXPECTING SNOWS TO FAN OUT ACROSS THE MAJORITY OF 
NORTHWEST LOWER/EASTERN UPPER THIS EVENING UNDER THE SHIFTING 
WINDS...BRINGING EVERYONE AT LEAST A PERIOD OF SNOW. THE STRONG 
1000-850MB WINDS OF 25-35KT WILL BE ABLE TO THROW SNOWS ACROSS 
MOST...IF NOT ALL OF THE CWA. THEREFORE LIKELY CHANCES EVEN RESIDE 
FOR NE LOWER...BUT NO SERIOUS ACCUMULATIONS THERE. BETTER LAKE SNOWS 
WILL FALL/STACK UP ACROSS FAR NW LOWER/CHIPPEWA COUNTY LATE TONIGHT 
THROUGH THURSDAY AS WINDS SETTLE IN...AND INVERSION HEIGHTS RISE 
FROM 4500/5000 FEET TO AN IMPRESSIVE 7500-8500 FEET. WITH MOISTURE 
FLUX REMAINING STRONG UNDER 30KT 1000-850MB FLOW...POTENTIAL HELP 
FROM LIGHT -DIVQ/SHORTWAVE...AND MOST INTERESTINGLY...FORECAST 
SOUNDINGS SHOWING A NICE BULLS-EYE OF MAX OMEGA CENTERED RIGHT AT 
THE -15C (ADDING THE FLUFF FACTOR)...WE ARE LOOKING AT THE POTENTIAL 
FOR SEVERAL MORE INCHES OF SNOW. HEADLINES WILL ALMOST CERTAINLY BE 
CONTINUED FOR SEVERAL COUNTIES...DUE NOT ONLY TO SNOWFALL...BUT 
BLOWING AND DRIFTING AS WELL. SNOWFALL OF 1-5 INCHES TONIGHT...BUT 
BOOSTED EXPECTED SNOWFALL THURSDAY TO 6 INCHES IN FAVORED REGIMES. 

THURSDAY NIGHT/FRIDAY...PROGRESSIVELY COLDER AIR WITH H8 TEMPS 
FALLING TO -20C AND LOSS OF CYCLONIC FLOW AND DEEPER MOISTURE. 
PLUS...SMALLER FLAKE SIZES AND LOSS OF MAX LIFT IN THE DGZ. STILL 
STRONG 1000-850MB FLOW OF 25KT OR SO...LOCKED IN WESTERLY FLOW...AND 
INVERSION HEIGHTS TO 5500-6500 FEET. CAN FORESEE MODERATE 
ACCUMULATIONS 2-5" INCHES EACH PERIOD ACROSS PARADISE AND FAR NRN/NW 
LOWER. HEADLINES MAY NEED TO BE EXTENDED THROUGH THIS TIME FRAME AS 
WELL.   

LATER PERIODS...NO SIGNIFICANT CHANGES. SMD

&&

.MARINE.../ISSUED AT 357 AM/

A POWERFUL LOW PRESSURE CENTER WILL CROSS THE CENTRAL GREAT LAKES 
TODAY AND TONIGHT. THIS LOW WILL BE OVER SOUTHERN LAKE MI THIS 
MORNING...EMERGE INTO LAKE HURON BY SUNSET...AND MOVE INTO ONTARIO 
BY MIDNIGHT TONIGHT. EASTERLY GALES WILL CONTINUE THROUGH EARLY 
AFTERNOON...WITH A LOW PROBABILITY OF STORM-FORCE GUSTS ON LAKE 
HURON. THE GREATEST THREAT OF STORM-FORCE GUSTS IS IN THE STRAITS 
REGION. WINDS WILL GRADUALLY SHIFT DIRECTIONS HAS THE LOW MOVES 
THROUGH...WITH WEST-NORTHWEST GALES DEVELOPING TONIGHT. WIDESPREAD 
SNOW WILL COMBINE TO SIGNIFICANTLY RESTRICT VISIBILITIES.

JH

&&

.AVIATION.../ISSUED AT 1233 PM/...VALID FOR 18Z TAFS

WIDESPREAD LIGHT TO MODERATE SNOW WILL CONTINUE AT THE TAF SITES 
THROUGH THE AFTERNOON HOURS WITH IFR/MVFR CIGS/VISBYS CONTINUING. WINDS 
WILL QUICKLY SHIFT FROM THE NORTH/NORTHEAST TO THE WEST BY THIS 
EVENING AND WILL INCREASE THROUGH THE EVENING. AS WINDS SHIFT AROUND 
TO THE WEST...THE EMPHASIS WILL TRANSITION FROM WIDESPREAD 
SNOWFALL...TO LAKE EFFECT...HITTING NORTHWEST LOWER MICHIGAN 
(KTVC/KPLN) MUCH HARDER THAN NORTHEAST LOWER MICHIGAN (KAPN). 
HOWEVER...DUE TO THE STRONG WINDS...SOME SNOW SHOWER ACTIVITY MAY 
MAKE IT INTO THE VICINITY OF KAPN OVERNIGHT. THIS LAKE EFFECT 
ACTIVITY WILL LINGER INTO THE DAY TOMORROW AND BEYOND.

KAS

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MIZ008-015>036-
     041-042.
LM...GALE WARNING UNTIL 11 PM EST THURSDAY FOR LMZ323-341-342-344>346.
LH...STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LHZ345>349.
LS...GALE WARNING UNTIL 11 PM EST THURSDAY FOR LSZ321-322.

&&

$$