FXUS61 KBUF 250848
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
348 AM EST FRI DEC 25 2009

.SYNOPSIS...
HIGH PRESSURE RIDGING SOUTHWARD FROM CANADA WILL KEEP THINGS DRY 
THROUGH THIS CHRISTMAS MORNING. MEANWHILE...LOW PRESSURE NEAR IOWA 
WILL LIFT A FRONT NORTH TOWARD NEW YORK STATE...BRINGING 
PRECIPITATION INTO THE REGION THIS AFTERNOON AND TONIGHT. TEMPERATURES 
WILL BE JUST ABOVE FREEZING IN MOST LOCATIONS. HOWEVER...EXPECT
POCKETS OF FREEZING RAIN MAINLY IN THE SOUTHERN TIER AND NORTH
COUNTRY.

&&

.NEAR TERM /THROUGH TONIGHT/...
WINTER WEATHER ADVISORY WILL REMAIN IN EFFECT THROUGH MUCH OF THE 
DAY TODAY FOR THE SOUTHERN TIER INTO THE FINGER LAKES REGION. 
PRECIPITATION TYPE WILL BE THE PRIMARY CONCERN THROUGH THE PERIOD. 

WARM AIR ALOFT HAS ALREADY PUSHED INTO THE AREA WITH THE 00Z KBUF
SOUNDING SHOWING 850 MB TEMPERATURES OF +3C. MODEL SOUNDINGS
INDICATING CONTINUED WARMING ALOFT TODAY...WITH 850 MB TEMPERATURES
APPROACHING +6C BY THIS AFTERNOON. THIS WILL BE PLENTY WARM
ENOUGH FOR THE PRECIPITATION TO BEGIN AS LIQUID.

REGIONAL RADARS EARLY THIS MORNING SHOWING A LARGE PRECIPITATION
SHIELD WORKING NORTHWARD FROM THE OHIO VALLEY WITH THE NORTHERN
EDGE PUSHING INTO WEST CENTRAL OHIO. RADAR TRENDS WOULD SUGGEST
RAIN REACHING THE WESTERN SOUTHERN TIER BETWEEN 8 AM AND 11
AM...THEN CONTINUING TO PUSH NORTHWARD THROUGH THE REMAINDER OF THE
DAY. SURFACE TEMPERATURES MORE THAN LIKELY WILL BE BELOW FREEING
OVER A GOOD PORTION OF THE SOUTHERN TIER AND INTO THE SOUTHERN
FINGER LAKES AS THE RAIN STARTS. MODEL QPF NOT OVERLY IMPRESSIVE...
BUT WE COULD SEE LOCAL ICE ACCRETIONS OF A TENTH TO A QUARTER INCH
WHERE TEMPERATURES STAY AT OR BELOW FREEZING THE LONGEST. MODEL
SOUNDING ALSO CONTINUING TO SUGGEST THAT THERE COULD BE ENOUGH
EVAPORATIVE COOLING OF THE COLUMN TO ALLOW FOR A BRIEF MIX WITH
SNOW OR SLEET.

THE REMAINDER OF THE REGION WILL HAVE SOME POCKETS OF FREEZING 
RAIN AT THE ONSET THIS MORNING OR EARLY THIS AFTERNOON...BUT
SURFACE TEMPERATURES WILL WARM ENOUGH BY MID AFTERNOON TO CHANGE
ALL THE PRECIPITATION TO RAIN.

THE BULK OF THE PRECIPITATION WILL REACH THE NORTH COUNTRY
TONIGHT. SURFACE TEMPERATURES WILL MOST CERTAINLY BE AT OR BELOW
FREEZING FOR MOST OF THE NIGHT WITH ADDITIONAL COOLING FROM THE
NORTHEAST DRAINAGE WINDS DOWN THE SAINT LAWRENCE VALLEY. THIS
PERIOD WILL HAVE TO BE MONITORED FOR MORE SUBSTANTIAL ICE
ACCRETIONS. THEREFORE WILL MAINTAIN WINTER STORM WATCH FOR THIS
AREA.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
THE PRIMARY SURFACE LOW OVER THE UPPER MIDWEST WILL REMAIN IN
PLACE THROUGH MOST OF SATURDAY...WHILE A SECONDARY LOW FORMS OFF
THE DELAWARE COAST. THE SURFACE TROUGH THAT STRETCHES BETWEEN THESE
TWO LOWS WILL STILL BE A FOCAL POINT FOR STEADY RAIN THROUGH
SATURDAY MORNING...BEFORE DRIER AIR WORKS IN BEHIND THE TROUGH
DURING THE AFTERNOON AND CAUSES THE PCPN TO TAPER OFF ACROSS
WESTERN NEW YORK AND THE GENESEE VALLEY. IN TERMS OF PCPN
TYPE...TEMPERATURES ALOFT AND AT THE SURFACE WILL SUPPORT MAINLY
RAIN ACROSS MOST OF THE AREA DURING THE MORNING HOURS. THE MAIN
EXCEPTION WILL BE ACROSS THE HIGHER ELEVATIONS EAST OF LAKE
ONTARIO WHERE SUB FREEZING SURFACE TEMPERATURES WILL STILL RESULT
IN THE POTENTIAL FOR SOME STEADY FREEZING RAIN.

SATURDAY AFTERNOON...TEMPERATURES ALOFT WILL GET COLD ENOUGH TO 
CAUSE SCATTERED RAIN SHOWERS TO MIX WITH OR CHANGE TO SNOW ACROSS 
WESTERN NY.  

SATURDAY NIGHT...PCPN WILL CONTINUE TO TAPER OFF FROM WEST TO EAST 
AS THE DRY SLOT WORKS FARTHER TO THE EAST. STILL EXPECT POCKETS OF 
FREEZING RAIN TO IMPACT AREAS EAST OF LAKE ONTARIO INTO SATURDAY 
EVENING. BECAUSE OF THE POTENTIAL THAT FREEZING RAIN MAY LAST 
THROUGH MOST OF THE DAY SATURDAY...IT MAY TAKE AWHILE BEFORE THE 
THREAT OF FREEZING AT THE SURFACE ENDS EVEN THOUGH THE AIR 
TEMPERATURE MAY RISE ABOVE FREEZING SATURDAY EVENING. 
THEREFORE...THE WINTER STORM WATCH FOR JEFFERSON AND LEWIS COUNTIES 
WILL REMAIN IN EFFECT THROUGH SATURDAY NIGHT. 

FOR THE REST OF THE AREA ON SATURDAY NIGHT...EXPECT THAT MOST OF THE 
PRECIPITATION WILL BE OVER AS THE COLDER AIR ADVECTS IN FROM THE 
WEST. 

ON SUNDAY...THE INFLUENCE FROM THE APPROACHING UPPER LEVEL LOW WILL 
INCREASE AS LOW LEVEL MOISTURE BEGINS TO INCREASE DURING THE 
AFTERNOON. THEREFORE...WILL INDICATE A WEST TO EAST INCREASE TO 
CHANCE POPS AS THE DAY WEARS ON. TEMPERATURES SHOULD BE COLD ENOUGH 
FOR PCPN TO FALL MAINLY AS SNOW ON SUNDAY. SOME LAKE ENHANCED SNOW 
IS POSSIBLE NORTHEAST OF LAKE ERIE LATE IN THE DAY. 

SNOW SHOWERS WILL CONTINUE TO SPREAD EAST ACROSS THE AREA SUNDAY 
NIGHT AS THE UPPER LEVEL LOW WORKS ACROSS NEW YORK STATE.
TEMPERATURES ALOFT WILL BE COLD ENOUGH FOR SOME LAKE ENHANCED SNOW
EAST OF BOTH LAKES.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A POLAR VORTEX DROPPING SOUTH FROM HUDSON BAY ON MONDAY WILL 
REINFORCE THE UPPER LEVEL TROUGH THAT WILL BE IN PLACE OVER THE 
LOWER GREAT LAKES AND NEW ENGLAND. AN ARCTIC FRONT THAT WILL BE 
ASSOCIATED WITH THE DEEPENING UPPER LEVEL TROUGH IS FORECAST TO DROP 
SOUTH ACROSS WESTERN AND CENTRAL NEW YORK MONDAY AFTERNOON. A 
GENERAL AREA OF SNOW IS EXPECTED TO ACCOMPANY THE FRONTAL PASSAGE 
...AND SOME LAKE ENHANCED SNOW POSSIBLE AS A SOUTHWEST FLOW SETS
UP AHEAD OF THE APPROACHING FRONT.

AS THE UPPER LEVEL LOW PASSES TO THE EAST MONDAY NIGHT...COLDER AIR ALOFT 
WILL CONTINUE TO POUR ACROSS THE REGION FROM THE NORTHWEST. A SHARP 
TEMPERATURE GRADIENT AT 850 WILL PASS ACROSS THE REGION EARLY MONDAY 
NIGHT WHICH MAY LEAD TO A QUICK BURST OF MODERATE SNOW. BY TUESDAY 
MORNING...850 MB TEMPERATURES ARE FORECAST TO RANGE FROM -20C TO 
-24C. 

WINDS WILL BECOME MORE NORTHWESTERLY TUESDAY AND TUESDAY NIGHT WITH 
LES ACROSS SKI COUNTY AND TO THE SOUTH AND EAST OF LAKE ONTARIO. AS 
A SFC HIGH PRESSURE NEARS THE REGION FROM THE WEST THIS LES WILL 
DIMINISH FIRST OFF LAKE ERIE AND LATER OFF LAKE ONTARIO. SFC 
TEMPERATURES TUESDAY WILL RANGE 10 TO 15 DEGREES BELOW NORMAL WITH 
MANY PLACES STRUGGLING TO MAKE IT OUT OF THE 20S. 

DRY WEDNESDAY WITH SFC HIGH PRESSURE ANCHORED OVER THE MID-ATLANTIC 
STATES. REMAINING COLD ALTHOUGH A LITTLE MORE SUNSHINE IS EXPECTED 
AS UPPER LEVEL MOISTURE DECREASES.

MODELS SHOW ANOTHER DISTURBANCE IN THE SOUTHERN BRANCH OF THE JET 
STREAM FOR LATE NEXT WEEK. FOR NOW WILL JUST GO WITH A LOW CHC POP 
AS MODELS WILL LIKELY VARY THEIR SOLUTION BASED ON HOW AND IF THE 
NORTHERN BRANCH OF THE JET STREAM INTERACTS WITH THE TIMING OF THIS 
FEATURE.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AS OF 05Z THE MVFR STRATUS LAYER IS GONE FROM ALL OF OUR SITES
EXCEPT FOR KART WHERE CIGS HAVE ACTUALLY LOWERED TO IFR LEVELS OF 700
FEET. WE EXPECT THIS AREA OF STRATUS TO SHRINK WITH CONDITIONS
IMPROVING TO VFR BY 08Z.

VFR WILL THEN PREVAIL ACROSS THE FORECAST AREA WITH JUST HIGH
CLOUDS OVERSPREADING THE AREA FROM SOUTHWEST TO NORTHEAST. LATEST
MODEL RUNS STILL SLOW TO BRING PRECIPITATION SHIELD IN FROM THE
STORM SYSTEM OVER THE CENTER OF THE COUNTRY. OUR TIMING WOULD BE
MIDDAY FOR KJHW AND MID TO LATE AFTERNOON FROM THE NIAGARA
FRONTIER TO THE FINGER LAKES REGION AND NOT UNTIL THE END OF THE
TAF PERIOD FOR KART. WITH DOWNSLOPING SOUTHEAST WINDS CEILINGS
WILL STILL REMAIN VFR WHEN THE PRECIPITATION BEGINS. EXPECT A
DETERIORATION TO MVFR AFTER 00Z FOR WESTERN SITES. 

IF PRECIPITATION STARTS EARLY ENOUGH...FREEZING RAIN MAY BE A
PROBLEM ACROSS THE SOUTHERN TIER FOR AWHILE. EVAPORATIONAL COOLING MAY
EVEN CHANGE PTYPE TO A WINTRY MIX.

OUTLOOK... 
FRIDAY NIGHT...IFR/MVFR IN RAIN AND PATCHY FREEZING RAIN.
SATURDAY...IFR/MVFR WITH RAIN CHANGING TO SNOW FROM WEST TO EAST.
SUNDAY AND MONDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS...WITH
LIMITED LAKE SNOWS POSSIBLE EAST OF THE LAKES.
TUESDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
ON LAKE ERIE...SOUTHEAST WINDS PICK UP TODAY. THEREFORE...A SMALL 
CRAFT ADVISORY REMAINS IN EFFECT. THOUGH THE SHORT FETCH ASSOCIATED 
WITH THE SOUTHEAST WINDS WILL NOT RESULT IN HIGH WAVES CLOSE TO THE 
NEARSHORES...THE WATER WILL BECOME CHOPPY. WINDS WILL DIMINISH AND 
SHIFT SW THROUGH THE WEEKEND.

ON LAKE ONTARIO...A E-NE FLOW WILL CONTINUE TODAY THROUGH SATURDAY. 
925 MB WINDS ARE STRONG...BUT NOT LINED UP WELL AT ALL WITH 
SURFACE...SO EXPECT MUCH OF THIS NOT TO MIX DOWN THROUGH THE 
INVERSION. FOR THIS REASON GO WITH A STRONG SMALL CRAFT INSTEAD OF 
GALES...CAPPING WINDS AT 30 KTS. WAVES SHOULD BUILD WELL ON WESTERN 
ONTARIO...WITH THE SCA LIKELY LASTING WELL INTO SATURDAY.

LOOKING AHEAD...THE PASSAGE OF A FRONTAL BOUNDARY LATE MONDAY...MAY 
PRODUCE GALES OR STRONG SCA CONDITIONS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY 
     NIGHT FOR NYZ007-008.
     WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST 
     THIS EVENING FOR NYZ019>021.
     WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 7 PM EST 
     THIS EVENING FOR NYZ013-014.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR 
         LOZ043.
         SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR LOZ042.

&&

$$

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