FXUS61 KBUF 230455
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1155 PM EST TUE DEC 22 2009

.SYNOPSIS...
HIGH PRESSURE WILL RIDGE SOUTHWARDS FROM CANADA THROUGH THURSDAY 
NIGHT. THIS WILL BRING GENERALLY FAIR WEATHER...HOWEVER NUISANCE 
LAKE EFFECT SNOW SHOWERS WILL DEVELOP SOUTHEAST OF LAKE ONTARIO 
TONIGHT AND WEDNESDAY. THE HIGH WILL PRODUCE FINE TRAVEL WEATHER FOR 
THE DAY BEFORE CHRISTMAS...BUT A SLOW MOVING LOW APPROACHING FROM 
THE UPPER MISSISSIPPI VALLEY WILL BRING US SOME RAIN AND FREEZING 
RAIN FOR CHRISTMAS DAY.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
UPDATE AS OF 10 PM...
ALL IS GOING WELL WITH THE 4 PM PACAKAGE AT THIS TIME. WE JUST HAD
TO UP THE TIMING OF SCATTERED SNOW SHOWERS ACROSS THE NIAGARA
FRONTIER AS THE SHORT WAVE ROTATING AROUND THE RETREATING UPPER
LOW HAS INCREASED SNOW SHOWER ACTIVITY A LITTLE EARLY. ALL ELSE
LOOKS GOOD.

THE BULK OF THE AFTERNOON DISCUSSION REMAINS BELOW.

OVER THE COURSE OF THE NEAR TERM PERIOD...A FAIRLY COMPACT UPPER 
LEVEL LOW CURRENTLY CENTERED NEAR WATERTOWN WILL DRIFT SOUTHEAST TO 
THE SOUTHERN NEW ENGLAND COAST. MEANWHILE AT THE SURFACE...LOW-LEVEL 
TROUGHING EXTENDING WESTWARD FROM LAST WEEKEND'S COASTAL STORM WILL 
DROP FROM THE SAINT LAWRENCE VALLEY SOUTHWARD INTO CENTRAL NEW 
ENGLAND/EASTERN NEW YORK STATE. THE FAIRLY DEEP CYCLONIC FLOW 
ASSOCIATED WITH THESE TWO FEATURES WILL HELP TO CIRCULATE A FAIR 
AMOUNT OF ATLANTIC MOISTURE BACK INTO MUCH OF THE AREA FOR TONIGHT 
AND WEDNESDAY...WHICH WILL BE ENHANCED BY A WEST-NORTHWESTERLY FLOW 
OF COLD AIR ACROSS THE CENTRAL AND EASTERN GREAT LAKES. AS A 
RESULT...EXPECT FAIRLY WIDESPREAD LOW CLOUDS TO REDEVELOP ACROSS THE 
AREA TONIGHT AND LINGER THROUGH WEDNESDAY MORNING...BEFORE STARTING 
TO ERODE A BIT IN THE AFTERNOON AS LOW-LEVEL RIDGING BEGINS TO NOSE 
INTO WESTERN NEW YORK STATE.

THE AFOREMENTIONED INCREASE IN MOISTURE COUPLED WITH THE STILL-COLD 
WEST-NORTHWESTERLY FLOW WILL ALSO LEAD TO THE REDEVELOPMENT OF SOME 
LAKE EFFECT SNOW SHOWERS SOUTHEAST OF LAKE ONTARIO TONIGHT...THOUGH 
THE ACTIVITY WILL BE LIMITED IN SCOPE BY RELATIVELY LOW INVERSION 
HEIGHTS OF 4-5 KFT...AND THE RELATIVELY SHORT FETCH ACROSS THE LAKE 
WHICH WILL FAVOR MORE OF A MULTIBANDED LES SCENARIO. AT THIS 
POINT...FRESH ACCUMS OF AN INCH OR SO LOOK REASONABLE FROM EASTERN 
MONROE COUNTY EAST TO OSWEGO COUNTY TONIGHT...WITH ANOTHER INCH OR 
TWO POSSIBLE ON WEDNESDAY. WILL KEEP LIKELY POPS IN PLAY FOR THIS 
AREA TONIGHT AND MUCH OF WEDNESDAY...THEN WILL TAPER BACK TO CHANCE 
LATER IN THE DAY AS THE CAPPING INVERSION LOWERS AND LOW-LEVEL SHEAR 
INCREASES. 

FURTHER TO THE WEST...THE COMBINATION OF PROGRESSIVELY LOWER 
INVERSION HEIGHTS AND GREATER AMOUNTS OF DIRECTIONAL SHEAR SHOULD 
RESULT IN AN EVEN MORE LIMITED LAKE RESPONSE...WITH ONLY SOME 
SCATTERED SNOW SHOWERS EXPECTED FROM ROCHESTER WESTWARD TO NIAGARA 
COUNTY...AND MERE FLURRIES EXPECTED SOUTHEAST OF LAKE ERIE. AS 
SUCH...WILL FORECAST POPS IN THE SLIGHT CHANCE TO CHANCE RANGE IN 
THESE LATTER AREAS. AREAS EAST OF LAKE ONTARIO WILL BE CLOSER TO 
THE UPPER LOW/SURFACE TROUGH AND MORE SUBJECT TO THE 
SCATTERED SNOW SHOWER ACTIVITY THAT WILL BE ASSOCIATED WITH THESE 
FEATURES...THEREFORE WILL CONTINUE TO INDICATE MORE GENERAL CHANCE 
POPS ACROSS THE NORTH COUNTRY FOR LATER TONIGHT AND MUCH OF 
WEDNESDAY.

AS FOR TEMPS...HAVE AIMED A BIT BELOW GUIDANCE THROUGH THE PERIOD. 
WITH PLENTY OF COLD AIR IN PLACE AT THE LOW LEVELS...MOS 
TEMPERATURES WAS UNIVERSALLY TOO WARM TODAY...AND WOULD BET ON 
A SIMILAR SCENARIO UNFOLDING TOMORROW GIVEN THAT THERE WILL BE 
LITTLE OR NO CHANGE IN OUR CURRENT AIRMASS...AND THE FACT THAT THERE 
WILL BE A FAIR AMOUNT OF CLOUD COVER AROUND. AS SUCH...HAVE FORECAST 
LOWS IN THE TEENS ACROSS MUCH OF THE AREA TONIGHT WITH SOME 
SINGLE-DIGIT READINGS IN THE NORTH COUNTRY...FOLLOWED BY HIGHS ONLY 
REACHING THE LOWER HALF OF THE 20S ON WEDNESDAY.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
WELL THE GOOD NEWS IS THAT FAIR WEATHER IS EXPECTED WEDNESDAY NIGHT 
THROUGH EARLY CHRISTMAS MORNING...WITH NO WEATHER RELATED ISSUES IN 
WESTERN NEW YORK. HIGH PRESSURE WILL CONTINUE TO RIDGE SOUTHWARD 
FROM CANADA...AS THE HIGH DRIFTS EAST FROM ONTARIO TO QUEBEC BY 
FRIDAY MORNING. 

ON WEDNESDAY NIGHT...A CLOSED 500 MB WILL SIT TO THE EAST...WITH 
LIGHT PRECIPITATION FORECAST TO WRAP ALL THE WAY AROUND THIS SYSTEM. 
LINGERING LAKE EFFECT SNOW SHOULD BE CUT-OFF AS THE INVERSION 
QUICKLY DROPS...ENDING INSTABILITY OFF OF LAKE ONTARIO. IN 
GENERALLY...ACCUMULATING SNOW IS NOT EXPECTED WEDNESDAY NIGHT 
ONWARD...SO LOCATIONS WHICH DO NOT HAVE SNOW ON THE GROUND BY 
THEN...WILL LIKELY BE SHUT OUT IN TERMS OF A WHITE CHRISTMAS.

OTHERWISE...LAKE EFFECT CLOUDS WILL LIKELY LINGER SOUTH OF LAKE 
ONTARIO WEDNESDAY NIGHT...WITH THE NAM BUFKIT SHOWING A FAIRLY 
SIGNIFICANT AMOUNT OF MOISTURE TRAPPED BENEATH THE INVERSION. THIS 
SHOULD MIX OUT SOMEWHAT ON THURSDAY...WITH A MIX OF SUN AND CLOUDS. 
WITH WARMER AIR GRADUALLY BUILDING IN...HIGHS WILL BE WARMER THAN 
THEY HAVE BEEN IN SOME TIME...WITH ABOVE FREEZING TEMPERATURES A 
POSSIBILITY IN MANY LOCATIONS. CLOUDS WILL APPROACH FROM THE 
SOUTHWEST...BUT NOW MODEL CONSENSUS KEEPS PRECIPITATION TO THE 
SOUTHWEST OF EVEN THE SOUTHERN TIER THROUGH 700 AM CHRISTMAS MORNING.

TIMING THE EXIT OF AN UPPER LOW IS ALWAYS ONE FEATURE THE MODELS 
STRUGGLE WITH MOST...AND UNFORTUNATELY THIS IS THE KEY TO FRIDAY AND 
SATURDAY/S FORECAST. 12Z RUNS ARE CONSIDERABLY SLOWER THAN YESTERDAY.

FOR WESTERN PORTIONS (BUFFALO-ROCHESTER-SOUTHERN 
TIER)...PRECIPITATION SHOULD START FRIDAY MORNING OR EARLY 
AFTERNOON...SPREADING FROM WEST TO EAST. TEMPERATURES WILL BEGIN THE 
MORNING BELOW FREEZING...WITH A SIGNIFICANT WARM LAYER WORKING IN 
ALOFT. THIS WARM LAYER WILL BE TOO WARM FOR SLEET...WITH RAIN OR 
FREEZING RAIN AT THE ONSET. THE WIND FIELD IS NOT VERY STRONG AT THE 
SURFACE...SO EXPECT WARMER AIR TO BE SLOW TO MOVE IN. THIS WILL BE 
MORE OF A PROBLEM IN THE VALLEYS IN THE SOUTHERN TIER WHERE ICING IS 
THE MOST SIGNIFICANT CONCERN. BUFFALO AND ROCHESTER MAY START OFF AS 
A PERIOD OF FREEZING RAIN...AND THIS WILL DEFINITELY BE A CONCERN 
FOR CHRISTMAS DAY TRAVEL. STILL TOO FAR OUT TO PIN TEMPERATURES 
DOWN...BUT IT WILL BE CLOSE.

FOR EASTERN PORTIONS (OSWEGO-WATERTOWN)...PRECIPITATION SHOULD START 
FRIDAY AFTERNOON. HERE...ITS HARD TO RULE OUT ANY PRECIPITATION 
TYPE...WITH THE FLOW ALOFT WEAKER...TEMPERATURES DO NOT WARM AS MUCH 
AT ALL LAYERS. THIS TOO WILL POSE TRAVEL DIFFICULTIES...WITH LIGHT 
ICING ALSO A POSSIBILITY.

TEMPERATURES SHOULD VERY SLOWLY RISE FRIDAY NIGHT...THOUGH PATCHES 
OF FREEZING RAIN CANNOT BE RULED OUT AS WELL. THROUGH THE 
PERIOD...PRECIPITATION WILL TEND TO BE OCCASIONAL...NOT TERRIBLY 
HEAVY...BUT ENOUGH TO ADD UP. QPFS SHOULD GENERALLY RUN .50 TO 1.00 
FOR FRIDAY THROUGH FRIDAY NIGHT. THIS BEARS WATCHING...BECAUSE IF 
TEMPERATURES DO STAY BELOW FREEZING IN SOME LOCATIONS...MORE 
SIGNIFICANT ICING COULD OCCUR. FOR NOW...EXPECT TEMPERATURES TO 
REMAIN ABOVE FREEZING IN MOST LOCATIONS FRIDAY NIGHT...THOUGH IT 
WILL BE CLOSE.

COLDER AIR WORKS IN FROM THE WEST ON SATURDAY...WITH AN EVENTUAL 
CHANGEOVER TO SNOW FROM WEST TO EAST. THE EUROPEAN IS ACTUALLY 
COLDER AND WETTER THAN THE GFS...SUGGESTING A MIX MAY OCCUR IN THE 
NORTH COUNTRY AS WELL...NEVER COMPLETELY CHANGING OVER TO PLAIN 
RAIN. FOR NOW...WILL GO WITH RAIN OR SNOW LIKELY...UPPING POPS FROM 
PREVIOUS RUNS. THE TRANSITION WILL CONTINUE SATURDAY NIGHT. QPFS 
VARY GREATLY...WITH THE EUROPEAN LOOKING A BIT OVERDONE...BUT 
SHOWING 1 INCH PLUS IN SPOTS. IT IS POSSIBLE THAT ACCUMULATING SNOW 
WILL OCCUR ON THE BACK SIDE OF THE SYSTEM...MAKING SATURDAY A TRICKY 
TRAVEL DAY.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE CLOSED 500 MB LOW WILL CONTINUE ITS SLOW EASTWARD 
PROGRESSION...BRINGING COOLER AIR ALOFT AND GENERALLY AN UNSETTLED 
PATTERN. BY SUNDAY...IT SHOULD BE COLD ENOUGH FOR ANY PRECIPITATION 
THAT DOES FALL TO BE SNOW. THE CLOSE PROXIMITY OF THE UPPER LOW (BUT 
UNCERTAIN EXACT TRACK) WILL PREVENT ANY SIGNIFICANT SYNOPTIC LOWS 
FROM DEVELOPING...BUT MAY RESULT IN INSTABILITY OR LAKE EFFECT SNOW 
SHOWERS THROUGH THE PERIOD. 

LOOKS TO BE A LESS THAN IDEAL SET UP FOR LAKE EFFECT FOR THE MOST 
PART...WITH A GFS/EUROPEAN CONSENSUS BRINGING THE UPPER LOW TO OUR 
SOUTH. HOWEVER...WITH 850 MB TEMPS DROPPING...THERE WILL BE AVAILABLE 
LAKE INDUCED ENERGY...WITH SUBTLE FEATURES THE KEY. GENERALLY FOR 
THE PERIOD...WITH MAINTAIN CHANCE POPS THROUGHOUT...WITH SLIGHTLY 
HIGHER END CHANCE POPS IN THE TYPICALLY FAVORABLE LAKE EFFECT 
REGIONS. WHILE A MAJOR EVENT IS NOT EXPECTED...AS OFTEN IS THE 
CASE...PERSISTENT BANDS COULD PRODUCE LOCALLY DECENT 
SNOWFALL...ALTHOUGH MOST LOCATIONS WILL NOT GET ANY SIGNIFICANT 
SNOWFALL THROUGH THIS PERIOD. TEMPERATURES WILL BE COOL...BUT WITH 
MOSTLY CLOUDY SKIES SHOULD HAVE MINIMAL DIURNAL SWINGS.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
A SHORT WAVE ROTATING ACROSS THE AREA ON THE WEST SIDE OF A
DEPARTING UPPER LOW WILL PRODUCE RATHER WIDESPREAD MVFR CIGS THE
REST OF THE NIGHT INTO MUCH OF THE REST OF THE TAF PERIOD. SOME
LAKE SNOWS MAY PRODUCE IFR VSBYS AT TIMES SOUTHEAST OF LAKE
ONTARIO.

OUTLOOK...
WEDNESDAY NIGHT...MVFR. 
THURSDAY...VFR WITH AREAS OF MVFR.
FRIDAY...DETERIORATION TO IFR/MVFR WITH RAIN BECOMING 
LIKELY...POSSIBLY STARTING AS A PERIOD OF FREEZING RAIN.
SATURDAY...IFR/MVFR WITH A MIX OF RAIN AND SNOW LIKELY. 
SUNDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
WILL EXTEND SCA INTO TOMORROW NIGHT FOR PORTIONS OF SOUTHERN LAKE 
ONTARIO. OTHERWISE...EXPECT A QUIET PERIOD ON THE LAKES UNTIL FRIDAY 
WHEN THE NEXT SYSTEM APPROACHES. AT THIS TIME...SMALL CRAFT ADVISORY 
CONDITIONS ARE THE MOST LIKELY IMPACT.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST WEDNESDAY FOR LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR LOZ042.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...JJR
SHORT TERM...APFFEL
LONG TERM...APFFEL
AVIATION...JJR/SAGE
MARINE...APFFEL/JJR