Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 171151
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
651 AM EST WED DEC 17 2014

.SYNOPSIS...
RAIN WILL FALL ACROSS MUCH OF THE REGION EARLY TODAY. LOW PRESSURE
WILL MOVE OFF TO NEW ENGLAND AND RAIN WILL CHANGE TO SNOW LATE IN
THE DAY. SNOW OVERNIGHT WILL HAVE GREATEST ACCUMULATIONS OVER THE
TUG HILL PLATEAU AND THE HILLS OF THE SOUTHERN TIER. HIGH PRESSURE
WILL RETURN BY FRIDAY AND SATURDAY WITH DRYING CONDITIONS AND
NEAR-NORMAL TEMPERATURES.

&&

.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE OVER CENTRAL LAKE ONTARIO WILL MOVE INTO SOUTHEASTERN
ONTARIO PROVINCE AS IT IS ASSIMILATED BY A DEEPENING COASTAL LOW.
THIS COASTAL LOW WILL CROSS INTO THE NEW ENGLAND MARITIME REGION AND
DRAW COLD AIR OVER THE FORECAST AREA DURING THE DAY AND TONIGHT.

RAIN SHOWERS WILL BE PREVALENT ACROSS MUCH OF THE FORECAST AREA
TODAY AS THE SURFACE LOW PROVIDES A BROAD AREA OF SYNOPTIC LIFT.
EXPECT A GRADUAL CHANGE OVER FROM RAIN TO SNOW AS COLDER AIR
INFILTRATES THE REGION...FROM ID AFTERNOON TO EARLY EVENING AND FROM
HIGHER TO LOWER ELEVATIONS.

SOUTHWESTERLY WINDS BECOMING WESTERLY WILL DIRECT THE REGIONS MOST
CONDUCIVE TO SNOW ACCUMULATION ACROSS THE WESTERN SOUTHERN TIER AND
OVER THE TUG HILL REGION. A CAPPED BOUNDARY LAYER WILL LIMIT
VERTICAL DEVELOPMENT AND THUS THE AMOUNT OF SNOW THIS EVENING AND
TONIGHT. EXPECT A COUPLE TO FEW INCHES IN THESE FAVORED AREAS WITH
AN INCH OR SO ELSEWHERE.

PERSISTENT COLD AIR ADVECTION WILL KEEP TEMPERATURES ON A SLOW
DOWNWARD TREND THROUGH THE DAY FROM WEST TO EAST AND FROM HIGH
ELEVATIONS TO LOW ELEVATIONS. UPPER 30S TO LOW 40S EARLY WILL FALL
TO UPPER 20S AND LOW 30S BY THE LATE AFTERNOON. LOW TEMPS TONIGHT
WILL SETTLE TO THE MID TO UPPER 20S INLAND AND THE LOW 30S ACROSS
LOWER ELEVATIONS AND CLOSER TO THE LAKES.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
ON THURSDAY A MID LEVEL CLOSED LOW AND ASSOCIATED SURFACE LOW WILL
ACCELERATE EASTWARD INTO THE CANADIAN MARITIMES LEAVING BEHIND A
MODESTLY COLD NORTHWEST FLOW REGIME ACROSS THE LOWER LAKES. ONE LAST
MID LEVEL VORTICITY MAXIMA WILL CROSS THE AREA IN THE MORNING ON THE
WESTERN PERIPHERY OF THE CLOSED LOW...PROVIDING A TEMPORARY INCREASE
IN LARGE SCALE ASCENT. LAKE INDUCED INSTABILITY WILL BE VERY
MARGINAL ON THURSDAY WITH EQUILIBRIUM LEVELS OF 4-5K FEET...JUST
ENOUGH TO SUPPORT VERY MODEST LAKE ENHANCEMENT SOUTHEAST OF THE
LAKES. ANY ACCUMULATIONS WILL BE LIMITED TO A COATING TO AN INCH IN
MOST AREAS. THE CHAUTAUQUA RIDGE WILL BENEFIT FROM UPSLOPE FLOW AND
POSSIBLY A WEAK CONNECTION TO LAKE HURON...WHICH MAY PRODUCE
ADDITIONAL AMOUNTS OF AROUND 2 INCHES IN SPOTS. TEMPERATURES WILL BE
VERY CLOSE TO SEASONAL NORMS WITH HIGHS IN THE MID 30S AT LOWER
ELEVATIONS AND AROUND 30 ON THE HILLS.

THURSDAY NIGHT AND FRIDAY MORNING LOW PRESSURE WILL CONTINUE TO MOVE
EAST INTO THE NORTH ATLANTIC WITH ANY SYNOPTIC SCALE SUPPORT COMING
TO AN END. THIS WILL JUST LEAVE NORTHWEST FLOW WITH SHALLOW
INVERSION HEIGHTS AND ANEMIC LAKE INDUCED INSTABILITY. THIS WILL
JUST SUPPORT SCATTERED FLURRIES AND LIGHT SNOW SHOWERS FOR THE MOST
PART WITH ANOTHER SPOTTY DUSTING TO AN INCH SOUTHEAST OF THE LAKES.
IT APPEARS TEMPERATURES BENEATH THE INVERSION REMAIN JUST COLD
ENOUGH AT -10C TO KEEP ICE NUCLEI IN THE CLOUD LAYER AND PREVENT
FREEZING DRIZZLE. OTHERWISE IT WILL REMAIN OVERCAST WITH NAM AND GFS
MODEL POINT SOUNDINGS SHOWING YET ANOTHER PERIOD OF ABUNDANT LOW
LEVEL MOISTURE TRAPPED BENEATH A STEEPENING SUBSIDENCE INVERSION.

BY FRIDAY AFTERNOON HIGH PRESSURE WILL BEGIN TO BUILD INTO THE LOWER
LAKES AND BRING AN END TO THE LIMITED LAKE EFFECT. THIS HIGH WILL
BUILD ACROSS SOUTHERN QUEBEC AND NEW ENGLAND FRIDAY NIGHT WITH A
CONTINUATION OF DRY WEATHER. IT APPEARS STRATUS WILL REMAIN LOCKED
IN PLACE WITH WEAK FLOW AND A STEEPENING INVERSION WITH GRAY
OVERCAST SKIES. THE ONE EXCEPTION MAY BE ACROSS THE NORTH COUNTRY
FRIDAY NIGHT WHERE MODEL GUIDANCE CONTINUES TO SHOW A STRONGER PUSH
OF DRYING MOVING SOUTH OUT OF CANADA.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL REMAIN IN PLACE SATURDAY ACROSS NORTHERN NEW
ENGLAND AND PROVIDE ANOTHER DRY DAY ALTHOUGH THERE MAY STILL BE A
GOOD DEAL OF CLOUD COVER. SATURDAY NIGHT AND SUNDAY THE LATEST GFS
AND ECMWF RUNS CONTINUE TO SHOW A VERY WEAK SYSTEM WITH A MID LEVEL
TROUGH LIFTING OUT OF THE OHIO VALLEY AND ACROSS THE LOWER LAKES AND
NEW ENGLAND. THIS MAY PRODUCE A FEW FLURRIES OR VERY LIGHT SNOW OF
LITTLE CONSEQUENCE.

FOLLOWING THIS SYSTEM DRY WEATHER WILL RETURN FOR SUNDAY NIGHT AND
MONDAY WITH WEAK HIGH PRESSURE IN PLACE. BY TUESDAY A STRONG TROUGH
WILL BEGIN TO DIG AND AMPLIFY INTO THE MID SECTION OF THE NATION.
THIS WILL FORCE DOWNSTREAM HEIGHT RISES AND WARM ADVECTION ACROSS
OUR REGION. THIS WILL BRING WARMER TEMPERATURES AND A CHANCE OF A
FEW RAIN SHOWERS.

LOOKING A LITTLE FARTHER AHEAD...THE GEFS ENSEMBLE MEAN TRENDS THE
NAO AND AO INDICES STEADILY DOWNWARD THROUGH THE END OF THE MONTH
INDICATING A GREATER POTENTIAL FOR HIGH LATITUDE BLOCKING. THE
STRONG ZONAL EASTWARD EXTENSION OF THE EAST ASIAN JET WILL GIVE WAY
TO MORE AMPLIFICATION ACROSS THE NORTH PACIFIC BY NEXT WEEK AND
ALLOW THE PATTERN ACROSS NORTH AMERICA TO AMPLIFY. EXPECT MID WINTER
COLD TO ARRIVE NEAR CHRISTMAS AND HAVE SOME STAYING POWER. THERE
CONTINUES TO BE STRONG SUPPORT IN OPERATIONAL AND ENSEMBLE GUIDANCE
OF A SIGNIFICANT SYSTEM USHERING IN THIS PATTERN CHANGE AROUND
CHRISTMAS. GIVEN THE STRENGTH AND COMPLEXITY OF THE EVOLVING PATTERN
FOCUSING ON THE OUTPUT OF ANY ONE MODEL RUN IS POINTLESS AT THIS
TIME RANGE...IT WILL STILL BE A FEW MORE DAYS BEFORE MODELS BEGIN TO
CONVERGE ON A COMMON SOLUTION. NONETHELESS A HIGH IMPACT SYSTEM
AROUND THE HOLIDAY APPEARS LIKELY SOMEWHERE IN THE NORTHEAST QUARTER
OF THE NATION. STAY TUNED.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE PASSING TO THE NORTH OF LAKE ONTARIO AND AN EXTENDED
UPPER TROUGH ALONG THE REST OF THE GREAT LAKES WILL MAINTAIN IFR
CONDITIONS FOR FAR WESTERN NY AND LOWER MVFR CONDITIONS ELSEWHERE.
RAIN AND LIGHT FOG WILL ALSO CREATE IFR FLIGHT CONDITIONS FOR
KJHW/KBUF/KIAG THROUGH THE MORNING.

COLDER AIR ARRIVING THROUGH THE DAY WILL CHANGE RAIN OVER TO SNOW BY
LATE AFTERNOON OR EVENING. CIGS AND VSBYS THIS EVENING THROUGH
TONIGHT WILL LIKELY BE IN THE MVFR CATEGORY FOR ALL SITES.

OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...VFR/MVFR WITH SCATTERED TO
OCCASIONALLY MORE NUMEROUS SNOW SHOWERS.
FRIDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS.
SATURDAY...VFR.
SUNDAY...VFR/MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
SURFACE LOW PRESSURE WILL MOVE TO THE NORTH OF THE LAKES TODAY AS A
COASTAL LOW STRENGTHENS. THE SURFACE PRESSURE GRADIENT WILL TIGHTEN
ACROSS THE LAKES AND COLD ADVECTION WILL BRING STRONGER SOUTHWEST TO
WESTERLY WINDS...WHICH WILL REQUIRE SMALL CRAFT ADVISORIES FOR BOTH
LAKES. HIGH PRESSURE BUILDS IN FRIDAY AND SATURDAY WITH A RETURN TO
MORE RELAXED CONDITIONS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THURSDAY FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR
         LOZ030.
         SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 4 AM EST
         FRIDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THURSDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM NOON TODAY TO 4 AM EST FRIDAY
         FOR LOZ045.

&&

$$

SYNOPSIS...WCH
NEAR TERM...WCH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...THOMAS
MARINE...WCH







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