FXUS63 KAPX 091144
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
644 AM 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 357 AM/...TODAY
637 AM UPDATE: WE ARE AWARE OF THE THUNDER. LIGHTNING JUST OCCURRED
HERE AT THE OFFICE 1137Z. JH
CURRENTLY...WELL...WE'RE DEFINITELY IN THE THICK OF THINGS NOW. SFC
LOW UNDERGOING CYCLOGENESIS AS IT LIFTS ACROSS NRN IL EARLY THIS
MORNING. 60KT H8 LLJ FEEDING COPIOUS GULF/ATLANTIC MOISTURE INTO THE
REGION. THIS STRONG FLOW IS RACING UP THE PRESSURE SFC'S (SEEN BEST
AT 285-290K) RESULTING IN INTENSE WAA/ISENTROPIC ASCENT MARKED BY
BULLS-EYE OF STRONG DEEP LAYER -DIVQ ACROSS NRN LOWER. OBSERVATIONS
ACROSS THE REGION SHOWING SNOWS ARE EVERYWHERE...WITH SOME OF THE
HEAVIER SNOWS NOW WORKING INTO AREAS SOUTH OF M-72. THE HEAVIEST
SNOW SYSTEM-WIDE...IS CURRENTLY FALLING ACROSS NE WISCONSIN WHICH
IS HELPED ALONG BY LAKE ENHANCEMENT OFF LAKE MICHIGAN.
THROUGH THE DAY...BIGGEST CHALLENGE IS WHERE THE SFC LOW WILL GO AS
THIS WILL BE CRITICAL FOR PLACEMENT OF HEAVIEST SNOW...AND ALSO FOR
PRECIP TYPE/SNOW AMOUNTS ACROSS THE FAR SE CWA. SFC PRESSURE FALLS
ARE CURRENTLY PINPOINTING A SFC LOW TRACK INTO SRN LAKE MICHIGAN
THEN ACROSS A WEST BRANCH TO HARRISVILLE LINE WITH WELL DEFINED
TROWAL SETTING UP ACROSS THIS REGION. BEST DEFORMATION SETS UP
ACROSS EASTERN UPPER AND LAKE MICHIGAN/FAR NW LOWER. LOW TO MID
LEVEL CORRIDOR OF FGEN LIFTS UP ACROSS THE SRN TIER OF COUNTIES
AND ALIGNS ITSELF IN BETWEEN THE TWO FOR SOME ENHANCED SNOWFALL
RATES/BANDING. SFC BASED WARM LAYER DOES EXCEED 1200 FEET SOUTH OF
OSCODA FROM MID MORNING TO EARLY AFTERNOON...BUT NOT AFTER 12 HR
WARNING CRITERIA SNOW FALLS IN WAA REGIME. WARNING CRITERIA SNOW
LOOKS GOOD ALL OTHER AREAS OF NRN LOWER WITH AXIS OF HIGHEST
SNOWFALL ACROSS FAR NW LOWER INTO DRUMMOND ISLAND. THE BEST LAKE
CONTRIBUTION TO THE SYSTEM SNOW WILL BE ACROSS SRN MACKINAC
COUNTY...WHERE THERE IS ACTUALLY A REAL DECENT CYCLONICALLY CURVED
FETCH FROM LAKE HURON...WHILE DELTA T'S ARE ON THE ORDER OF
15-17C.
WINDS ARE ALSO A CONCERN ON THE NORTH END OF THIS SYSTEM. EASTERLY
WINDS MAY BRIEFLY GUST INTO THE 40 MPH RANGE ACROSS THE STRAITS
REGION DUE TO COASTAL CONVERGENCE...IMPACTING THE SRN SHORE OF
MACKINAC ISLAND WHILE SNOWS ARE FAIRLY INTENSE. HOWEVER...WINDS WILL
BE GRADUALLY SHIFTING THROUGH THE ENTIRE DAY...AND ALTHOUGH BLIZZARD
CONDITIONS MAY OCCUR...AM NOT EXPECTING THIS TO LAST FOR 3HRS OR
MORE. WILL CONTINUE TO HAMMER THIS HARD IN HWO/WSW PRODUCTS.
SMD
&&
.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 641 AM/...VALID FOR 12Z TAFS
TODAY THRU 18Z: IFR/LIFR IN SNOW OF VARYING INTENSITY. GREATEST
CHANCE FOR 1/4SM +SN WILL OCCUR BEFORE 17Z. VCTS CONTINUES THRU 13Z.
STRONG NE WINDS WILL GRADUALLY SHIFT AS LOW PRESSURE MOVES ACROSS
CENTRAL LWR MI.
AFTER 18Z: SNOW DIMINISHES IN INTENSITY AND WINDS CONTINUE GRADUAL
SHIFTING. EXPECT IFR CIGS TO REMAIN EVEN THO VSBYS COULD IMPROVE TO
MVFR IN -SN.
TONIGHT: LAKE-ENHANCED SHSN'S WILL CONTINUE WITH MOST PERSISTENCE AT
PLN TVC. WINDS GRADUALLY SHIFT FROM NNW TO WNW.
JH/SMD
&&
.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.
&&
$$
