FXUS63 KAPX 222014
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
314 PM EST TUE DEC 22 2009

.SYNOPSIS.../ISSUED AT 314 PM/

HIGH PRESSURE WILL INFLUENCE THE GREAT LAKES THROUGH THURSDAY... 
PROVIDING THE REGION WITH DRY AIR...AND INSIGNIFICANT WEATHER. 
CLOUDS WILL INCREASE THURSDAY AND THURSDAY NIGHT...AHEAD OF AN 
APPROACHING WINTER STORM. THIS STORM WILL BRING A PERIOD OF MIXED 
WINTRY PRECIPITATION TO THE NORTH WOODS...FROM LATE CHRISTMAS EVE 
INTO CHRISTMAS DAY. SOME LIGHT SNOW WILL LINGER INTO THIS 
WEEKEND...AS THE STORM GRADUALLY WEAKENS AND EXITS THE REGION. SOME 
LAKE EFFECT SNOW IS THEN EXPECTED TO DEVELOP EARLY NEXT WEEK.

JH

&&

.SHORT TERM.../ISSUED AT 314 PM/...TONIGHT

FAIRLY BENIGN WX TO CONTINUE INTO THE OVERNIGHT...THOUGH CERTAINLY 
NOT WITHOUT ISSUE (PAR FOR THE COURSE UP THIS WAY)...NAMELY CLOUD 
TRENDS THRU THE OVERNIGHT AS WELL AS EFFECT ON LOW TEMPS. LOW LEVEL 
RIDGING TO REMAIN FIRMLY PLANTED ACRS THE REGION OVERNIGHT...WITH 
QUITE DRY AIRMASS (PWATS A MEAGER 0.15 INCHES) AND PLENTY OF SNOW 
COVER CERTAINLY SUPPORT OF A POTENTIALLY VERY COLD NIGHT GIVEN SLACK 
BOUNDARY LAYER FLOW. HOWEVER...THE PROVERBIAL FLY IN THE OINTMENT 
THIS GO AROUND IS EXPANSIVE LOW STRATUS/STRATOCU DECK RESIDING JUST 
NORTH OF THE AREA...BEGINNING TO MAKE MORE SIGNIFICANT PROGRESS 
TOWARD EASTERN UPR AS OF 19Z. PER EXPECTED EVER-SO-SLOW BACKING OF 
BOUNDARY LAYER FLOW TOWARD THE NORTH LATER TONIGHT...CAN ENVISION A 
BAND OF RESIDUAL STRATUS SNEAKING SOUTH BENEATH RATHER HEALTHY LOW 
LEVEL INVERSION...AUGMENTED BY REMAINING OVERLAKE INSTABILITY. THIS 
IDEA IN LINE WITH BOTH OBSERVED SATELLITE TRENDS THE PAST FEW HOURS 
AS WELL AS BOTH NAM AND GFS FCST SOUNDINGS...AND DIFFICULT TO ARGUE 
AGAINST PER CLIMO OF SUCH SNEAKINESS DURING SIMILAR RIDGING 
SCENARIOS. THIS OF COURSE MAKES FOR A VERY IFFY TEMP FCST 
OVERNIGHT...AS DO ANTICIPATE A QUICK DROP MOST SPOTS...THOUGH LIKELY 
SUBDUED AFTER 06Z NORTH AS LOWER CLOUD ADVANCES FROM THE NORTH. WILL 
KEEP OVERNIGHT LOWS BELOW GUIDANCE NUMBERS (MAINLY 0-10F THOUGH 
LOCALLY COLDER)...IN LINE WITH NUMBERS PRODUCED BY PREVIOUS 
SHIFT...THOUGH CERTAINLY WILL HAVE TO WATCH PROGRESSION OF CLOUD 
COVER. COULD ALSO SEE A TOUCH OF FOG DEVELOP PENDING QUICK DROP THIS 
EVENING...ESPECIALLY WITH SUNSHINE TODAY HELPING MELT TOP LAYER OF 
SNOW A BIT...THOUGH NOT WORTH A MENTION AT THIS TIME GIVEN 
ANTICIPATED PATCHY NATURE.

LAWRENCE

&&

.LONG TERM.../ISSUED AT 314 PM/...WEDNESDAY AND BEYOND

QUIET WEATHER THROUGH MIDWEEK WITH INDUCED UPPER RIDGE ACROSS THE 
GREAT LAKES...WITH ALL ATTENTION TURNING TOWARD OUR COMPLEX AND 
DIFFICULT STORM SYSTEM FOR CHRISTMAS.  WITH THIS SAID...MAIN 
FORECAST ISSUES REVOLVING AROUND POPS AND PRECIPITATION TYPE ON 
CHRISTMAS EVE AND CHRISTMAS DAY.  

WEDNESDAY AND WEDNESDAY NIGHT...QUIET WEATHER AND SEASONABLE 
TEMPERATURES AS UPPER RIDGING SLIDES ACROSS THE GREAT LAKES.  
INCREASING CLOUDS BY WEDNESDAY NIGHT AS WARMER AIR BEGINS TO MAKE A 
PUSH NORTHWARD IN ADVANCE OF DEVELOPING LOW OVER THE PLAINS.  THESE 
CLOUDS SHOULD HELP TO KEEP TEMPS WARMER THAN PREVIOUS NIGHTS...WITH 
MOST AREAS IN THE TEENS /SINGLE DIGITS COLDER LOCATIONS?/.  

THURSDAY INTO CHRISTMAS...NOW THE FUN...MODELS STILL SHOWING PLENTY 
OF DIVERGENCE IN SOLUTIONS WITH NUMEROUS DISCREPANCIES ON THE AMOUNT 
OF PHASING THAT WILL TAKE PLACE AND HOW RAPIDLY THE SYSTEM IN THE 
PLAINS DEEPENS /WHICH IMPACTS HOW QUICKLY IT MIGHT OCCLUDE AND CUT 
OFF THE WARM AIR PUSH TO THE NORTH/.  THE GFS IS THE COLDEST OF THE 
SOLUTIONS...AS IT OCCLUDES THE SYSTEM TO OUR SOUTHWEST THE 
FASTEST...THEREBY CUTTING OFF THE WARMER AIR PUSH TO THE NORTH. 
ALTHOUGH THERMALLY AN OUTLIER...THE GFS STRENGTH/POSITION DOES HAVE 
SUPPORT FROM ECMWF AND ENSEMBLES.  TO MAKE MATTERS MORE 
COMPLICATED...THE 12Z CANADIAN WANTS TO DEVELOP A SECONDARY AREA OF 
LOW PRESSURE TOWARD THE EASTERN LAKES...THEREBY KEEPING NORTHERN 
MICHIGAN COLDER AND POINTING MORE TOWARD FROZEN PCPN.  

SO WHAT TO DO?  PREFER THE CONSISTENCY OF THE ECMWF OVER THE PAST 
SEVERAL RUNS AND IT APPEARS TO HAVE A REASONABLE COMPROMISE BACKED 
UP BY THE ENSEMBLE ENVELOPE OF SOLUTIONS.  BASED ON THAT... UPPER 
FEATURE SLIDES TOWARD SOUTHERN WISCONSIN ON CHRISTMAS DAY WITH 
SURFACE FEATURE OVER NORTHERN IOWA.  AMBIENT DRY AIRMASS ACROSS 
NORTHERN MICHIGAN BEING REINFORCED SOMEWHAT BY EAST/SOUTHEAST LOW
LEVEL FLOW. SO ATMOSPHERE WILL TAKE SOME TIME TO MOISTEN UP AND
PCPN MAY NOT DEVELOP UNTIL AFTER MIDNIGHT ON THURSDAY NIGHT.
TAKING INTO ACCOUNT WET BULBING WITH AMBIENT DRY AIR...MOST LIKELY
PERIOD FOR FROZEN/FREEZING PCPN WILL BE LATE THURSDAY NIGHT INTO
CHRISTMAS MORNING. WITH SO MUCH UNCERTAINTY IN RELATIVELY SMALL
VARIATIONS IN LOW LEVEL THERMAL PROFILES...WILL NOT GET TOO
DETAILED THIS FAR OUT AND WILL GO WITH BROAD BRUSHED
RAIN/SNOW/FREEZING RAIN LIKELY. AFTER INITIAL PUSH OF WARM AIR
ADVECTION PCPN INTO CHRISTMAS MORNING... NORTHERN MICHIGAN MAY BE
"DRY SLOTTED" FOR THE MIDDAY/AFTERNOON HOURS WITH DRIZZLE AND FOG.
THE HIGHER TERRAIN AND PARTS OF EASTERN UPPER MAY STRUGGLE TO GET
MUCH ABOVE FREEZING AT THE SURFACE...AND LIGHT ICING PROBLEMS
COULD CONTINUE INTO THE AFTERNOON HOURS.

CHRISTMAS NIGHT AND BEYOND...STRONG OCCLUDED FRONT SWINGS ACROSS THE 
AREA CHRISTMAS NIGHT AND ANY LEFTOVER PCPN WILL CHANGE BACK TO LIGHT 
SNOW.  NEBULOUS FORECAST FOR THE WEEKEND WITH UPPER FEATURE BLOCKED 
FROM COMING EAST AND JUST MEANDERING AROUND THE WESTERN LAKES.  
LIMITED FORCING ACROSS OUR AREA BUT PLENTY OF MOISTURE...SO LIKELY 
SOME NUISANCE LIGHT SNOW/"SNIZZLE" TYPE PCPN ISSUES...BUT NOT 
EXPECTING MUCH IN THE WAY OF ACCUMULATION.  TEMPERATURES RETURNING 
TO BELOW NORMAL...WITH HIGHS GENERALLY IN THE 20S AND LOWS IN THE 
SINGLE DIGITS/TEENS.  LAKE EFFECT SNOWSHOWERS RETURN TO THE FORECAST 
FOR EARLY NEXT WEEK AS SEVERAL PIECES OF NORTHERN STREAM ENERGY MOVE 
ACROSS THE AREA.  

JK  

&&

.MARINE.../ISSUED AT 439 AM/

SURFACE RIDGE WILL RESULT IN A LIGHT NORTHERLY/NORTHEASTERLY FLOW
ACROSS THE UPPER LAKES THROUGH WEDNESDAY EVENING. WINDS WILL BEGIN
TO INCREASE LATER WEDNESDAY NIGHT INTO CHRISTMAS EVE OUT AHEAD OF
LOW PRESSURE APPROACHING FROM THE SOUTH.

AJS

&&

.AVIATION.../ISSUED AT 1234 PM/...VALID FOR 18Z TAFS

HIGH PRESSURE WILL HOLD FIRM ACROSS THE REGION THROUGH THE TAF
PERIOD...THOUGH WILL BE DEALING WITH SOME PESKY LOWER CLOUD ISSUES
AT ALL TERMINAL SITES THIS AFTERNOON INTO TONIGHT. SPECIFICALLY...
APPEARS LOW END VFR TO LOCALLY MVFR STRATOCU DECK WILL HANG AROUND
KAPN THE NEXT FEW HOURS BEFORE GRADUALLY BEING DISRUPTED LATER
THIS EVENING WITH ONSET OF LIGHTER WIND REGIME. THEREAFTER...WILL
BE WATCHING FOR AN AREA OF LOWER CLOUDS ACROSS SOUTHERN ONTARIO TO
SLOWLY SLIP IN FROM THE NORTH/NORTHEAST LATER TONIGHT...LIKELY
BRINGING A PERIOD OF MVFR CEILINGS TO ALL TERMINAL SITES ROUGHLY
06Z-15Z.

LAWRENCE

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
LH...NONE.
LS...NONE.

&&

$$