FXUS63 KAPX 111742
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1242 PM EST FRI DEC 11 2009

.SYNOPSIS.../ISSUED AT 455 AM/

LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH TONIGHT ACROSS 
NORTHERN MICHIGAN AS A RATHER COLD AIR MASS REMAINS ENTRENCHED OVER 
THE REGION. SNOW SHOWERS ARE EXPECTED TO WIND DOWN SATURDAY AS 
A RIDGE OF HIGH PRESSURE BUILDS INTO THE STATE AND WARMER AIR BEGINS 
TO RETURN. HOWEVER...THIS PUSH OF WARMER AIR WILL ALSO RESULT IN A 
RENEWED CHANCE FOR MORE WIDESPREAD LIGHT SNOW FOR THE LATTER HALF OF 
THE WEEKEND...WITH SEVERAL ADDITIONAL CHANCES FOR SNOW THROUGH THE 
FIRST HALF OF THE COMING WORK WEEK. THEREAFTER...IT APPEARS 
INCREASINGLY LIKELY ANOTHER SURGE OF ARCTIC AIR AND PLENTIFUL LAKE 
EFFECT SNOWS WILL MAKE AN APPEARANCE FOR THE LATTER HALF OF NEXT 
WEEK.

&&

.SHORT TERM.../ISSUED AT 1112 AM/...THIS AFTERNOON

12Z SURFACE/COMPOSITE ANALYSIS SHOWS CONTINUED WEST-NORTHWEST FLOW 
ACROSS THE UPPER GREAT LAKES REGION...WITH A BROAD AREA OF HIGH 
PRESSURE OVER THE OHIO VALLEY/SOUTHEASTERN U.S..  MULTIPLE BAND 
CONVECTION CONTINUES TO COME IN OFF LAKE MICHIGAN...WITH A STRONG 
WEST-NORTHWEST BAND OVER SOUTHERN LAKE SUPERIOR POUNDING FAR 
NORTHWEST CHIPPEWA COUNTY WITH 1+ INCH/HR SNOWFALL RATES.  12Z APX 
SOUNDING SHOWS INVERSION HEIGHT AROUND 775MB/850MB TEMPERATURE DOWN 
TO -21C.  AWAY FROM THE LAKE EFFECT AREAS HOWEVER...SKIES ARE SUNNY 
(A REFRESHING BREAK).  FORECAST ISSUES FOR THE AFTERNOON OF COURSE 
REVOLVE AROUND REMAINING LAKE CONVECTION.

EASTERN UPPER...HOW LONG DOES THE BAND AROUND WHITEFISH BAY HANG 
ON?  RADAR TRENDS ALREADY SUGGEST WESTERN END OF THE BAND OUT EAST 
OF THE KEWEENAW PENINSULA STARTING TO DRIFT WESTWARD AS SURFACE 
WINDS BACK MORE SOUTHWEST (SUCH AS AT STANNARD ROCK).  PROVIDED THIS 
TREND HOLDS...THIS WOULD SUGGEST THAT THE STRONGEST CONVERGENCE WILL 
ALSO SHIFT NORTH WITH TIME FARTHER OUT INTO THE LAKE AND EVENTUALLY 
SHIFT THE HEAVY SNOW BAND FARTHER NORTH INTO ONTARIO BY MID 
AFTERNOON.  FORECAST WILL REFLECT THAT THINKING.  OTHERWISE WITH DEW 
POINTS STILL WELL BELOW ZERO DIURNAL CLOUDS WILL BE SOMEWHAT LIMITED 
AT LEAST A LITTLE FARTHER INLAND FROM LAKE MICHIGAN.  CLOSER TO ST. 
IGNACE SOME CLOUDS AND LIGHT SNOW/FLURRIES MAY CLIP THE REGION IN 
WESTERLY FLOW OFF LAKE MICHIGAN.    

NORTHERN LOWER...IMPRESSIVE INSTABILITY REMAINS OVER NORTHERN LAKE 
MICHIGAN WITH LAKE INDUCED CAPE VALUES AROUND 1100J/KG...THOUGH 
COLDER TEMPERATURES STARTING TO RESULT IN SMALLER SNOWFLAKE SIZE.  
BUT SNOW HAS BEEN MODERATE AT TIMES THIS MORNING UNDER THE HEAVIER 
BANDS AND ROADS ARE A MESS IN MANY AREAS WEST OF I-75/NORTH OF 
M-32.  BANDS ARE SHOWING A SUBTLE BACKING AT LATE MORNING...BUT IN 
GENERAL WILL REMAIN WEST-EAST ORIENTED THROUGH THE AFTERNOON WITH 
HIGHEST INTENSITY SNOWFALL IMPACTING AREAS NORTH OF M-32 DOWNWIND OF 
LONGEST FETCH.  INSTABILITY WANES A BIT THIS AFTERNOON AS INVERSION 
HEIGHTS COME DOWN TOWARD 850MB...BUT THINK UP TO AN ADDITIONAL 3 
INCHES WILL OCCUR UNDER MORE PERSISTENT BANDS THIS AFTERNOON.  AS 
FOR HEADLINES...WINTER STORM WARNING WILL REMAIN UP FOR FAR 
NORTHWEST LOWER GIVEN RATHER LOUSY TRAVEL CONDITIONS NOTED EARLIER.  
WINTER WEATHER ADVISORY SURROUNDING THE WARNING THAT WAS TO EXPIRE 
AT MIDDAY WILL ALSO BE STRETCHED OUT INTO THE AFTERNOON GIVEN 
OCCASIONALLY LOWER VISIBILITIES AND GUSTY WINDS.  FARTHER INLAND 
ACROSS NORTHEAST LOWER WHERE SKIES ARE CURRENTLY PARTLY/MOSTLY SUNNY 
SHOULD SEE MORE IN THE WAY OF DIURNAL CLOUDS DEVELOPING THIS 
AFTERNOON...WITH AT LEAST SOME FLURRIES STRETCHING FARTHER INLAND.  

JPB 

&&

.LONG TERM.../ISSUED AT 455 AM/...TONIGHT AND BEYOND

TONIGHT...LAKE EFFECT SNOW SHOWERS WILL PERSIST TONIGHT AS WINDS
SHIFT FROM WESTERLY TO SOUTHWEST. ACCUMULATIONS WILL BE MUCH
LIGHTER...AS LES CONDITIONS BECOME MUCH MORE HOSTILE. CONTINUED
LOWERING INVERSION WITH SUBSIDENCE AND DEPARTING MOISTURE WILL
COUPLE WITH INCREASING ANTICYCLONIC FLOW AS SFC HIGH PUSHES INTO
THE REGION. WILL HAVE A COUPLE OF INCHES FOCUSED MORE AROUND
WESTERN EMMET/CHARLEVOIX COUNTIES. AWAY FROM THE LAKES
INFLUENCE...MORE CLEARING EXPECTED WITH LOWS DIPPING INTO THE
SINGLE DIGITS. 

SATURDAY THROUGH SUNDAY...TOUGH TO DISCERN HOW THIS TIME FRAME
WILL PLAY OUT...AS NRN STREAM ENERGY LOOKS TO AFFECT MAINLY
ONTARIO...WHILE SRN JET STREAM EJECTS SHORTWAVE ACTIVITY OUR WAY
SATURDAY NIGHT AND SUNDAY. LIKELY SOME WEAK LES IN SW FLOW REGIMES
POSSIBLY ENHANCED LATE IN THE DAY SATURDAY AHEAD OF LEAD SRN
STREAM WAVE...PROVIDED THAT LOW LEVEL WARMING DOESN'T TRY AND
STABILIZE THE LAKES. BY SATURDAY NIGHT...WAA/ISENTROPIC ASCENT
ARRIVES TO BRING SOME GENERAL LIGHT SYSTEM SNOW TO THE REGION WITH
MAYBE SOME SHALLOW LAKE HELP. THE LIGHT SNOW EJECTS OUT OF HERE
SUNDAY...LEAVING BEHIND AN INCH OR TWO PERHAPS. COULD EVEN BE
LOOKING AT SOME DRIZZLE/FREEZING DRIZZLE. NOTHING VERY DEFINED AT
THE MOMENT...BUT TEMPERATURES SHOULD UNDERGO A DECENT WARMING.
HIGHS RISE INTO THE MID 20S/NEAR 30 SATURDAY AND INTO THE LOWER
HALF OF THE 30S FOR SUNDAY. 

SUN NIGHT THRU TUE NIGHT...GIST OF GOING FCST LOOKS PRETTY 
GOOD...WITH PATTERN BRIEFLY RELAXING BUT OVERALL WX NOT SETTLING 
DOWN MUCH ACRS NORTHERN MICHIGAN. AS IS TYPICALLY THE CASE UP THIS 
WAY...PATTERN RELAXATION/WARM ADVECTION REGIMES USUALLY LEAD TO MORE 
SNOW/PRECIP CHANCES AND THIS NO EXCEPTION. APPEARS A BRIEF BREAK IN 
THE ACTION ON TAP SUN NIGHT WITH WEAK LOW LEVEL RIDGE AXIS BRANCHING 
THRU THE REGION AND FLOW REGIME QUITE ANTICYCLONIC AND CONVOLUTED. 
THEREAFTER...00Z GUIDANCE SUITE LATCHING ONTO NEXT SHORTWAVE 
EMERGING FROM THE FOUR CORNERS AREA AND HEADING TOWARD THE NORTHERN 
GREAT LAKES LATER MONDAY...DRIVING SOME SORT OF SFC RESPONSE (LOW 
PRESSURE) INTO NORTHERN MICHIGAN. RATHER GOOD AGREEMENT REGARDING 
THIS FEATURE AT THIS POINT...BUT COULD BE SOME PTYPE ISSUES ACRS THE 
SOUTH GIVEN PROGGED RATHER HEALTHY SURGE OF WARM ADVECTION. WILL 
LEAVE GOING CHANCE POPS INTACT AT THIS POINT BUT CAN FORESEE NEED TO 
BUMP TOWARD LIKELY PENDING CONTINUED GUIDANCE AGREEMENT. 
THEREAFTER...NEXT SHOT OF QUITE CHILLY AIR SET TO ROLL INTO THE AREA 
TUE/TUE NIGHT...PERHAPS ON THE HEELS OF CLIPPER SYSTEM TO DELIVER 
SOME LIGHTER SNOW EARLY TUESDAY. GOING LIKELY LAKE EFFECT POPS TUE 
NIGHT AND BEYOND LOOK GREAT. TEMPS HANGING NEAR CLIMO EARLY THEN 
HEADED TOWARD THE DEEP FREEZE INTO MIDWEEK.

LAWRENCE

&&

.MARINE.../ISSUED AT 455 AM/

SLIGHT DIURNAL DECREASE IN THE WINDS ATTM TO BELOW GALE CRITERIA.
HOWEVER...HIGH INSTABILITY OVER THE LAKES LIKELY STILL PRODUCING
GALES OVER THE NEARSHORE WATERS. PLUS...WITH MIXING DURING THE
DAY...GALES LIKELY TO PERSIST THROUGH THE DAY. WINDS DO WEAKEN A
TOUCH TONIGHT...SO WILL KEEP HEADLINES AS THEY ARE. CONDITIONS
WILL STILL BE RATHER ROUGH...WITH SMALL CRAFT ADVISORY CRITERIA
TONIGHT THROUGH AT LEAST SATURDAY NIGHT. LAKE EFFECT SNOW SHOWERS
WILL ONLY ADD TO THE NASTY CONDITIONS...ALTHOUGH A DOWNWARD TICK
IN THE INTENSITY OF THE SNOW IS EXPECTED BY SATURDAY. SNOW CHANCES
RETURN SAT NIGHT-SUNDAY...WITH LAKE EFFECT FOR THE NEXT WORK WEEK.

SMD 

&&

.AVIATION.../ISSUED AT 1239 PM/...VALID FOR 18Z TAFS

IFR CONDITIONS EXPECTED TO PREVAIL AT PLN INTO THIS EVENING BEFORE
LAKE SNOW SHOWER INTENSITY BEGINS TO WANE. IFR CONDITIONS AT TVC
EXPECTED TO IMPROVE TO MVFR BY MID AFTERNOON...THEN VFR/HIGH END
MVFR BY THIS EVENING. MAINLY VFR CONDITIONS EXPECTED AT APN UNLESS
A ROGUE SNOW SHOWER MOVES IN THIS AFTERNOON.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ018-
     020-023-025>028-031-032.
     WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR MIZ016-
     017-019-021-022.
LM...GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR LMZ323-341-342-
     344>346.
LH...GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR LHZ345>349-362.
LS...GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR LSZ321-322.

&&

$$