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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBUF 090325
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1025 PM EST SUN DEC 8 2013

.SYNOPSIS...
A WARM FRONT WILL CROSS THE AREA TONIGHT WITH LIGHT SNOW CHANGING
OVER TO FREEZING DRIZZLE...THEN EVENTUALLY TO DRIZZLE ON MONDAY. A
COLD FRONT WILL MARCH ACROSS THE REGION LATER ON MONDAY USHERING IN
MUCH COLDER TEMPERATURES ALONG WITH A POTENTIAL FOR SIGNIFICANT LAKE
EFFECT SNOWS THAT WILL REMAIN FOR MUCH OF THE COMING WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
REGIONAL RADARS THIS EVENING DISPLAY A BAND OF LIGHT SNOW ADVANCING
NORTHWARD THROUGH WNY...NOW REACHING NEAR THE SOUTHERN SHORELINE OF
LAKE ONTARIO. ACCUMULATIONS WITH THIS BAND OF SNOW ARE LIGHT
GENERALLY LESS THAN AN INCH. OTHERWISE SCATTERED LIGHT PRECIPITATION
CONTINUES TO FALL BEHIND THIS BAND OF SNOW THIS LATE EVENING.
PRECIPITATION CONTINUES MAINLY AS SNOW THOUGH WITH MID LEVEL DRIER
AIR AS EVIDENT ON WATER VAPOR IMAGERY JUST NOW REACHING NORTHERN PA
THIS LATE EVENING EXPECT SOON A CHANGE TO SOME FREEZING DRIZZLE.
LOCAL MODEL SOUNDINGS SHOW THIS MID LEVEL DRIER AIR SHOULD EXPAND
ACROSS THE CWA OVERNIGHT ALLOWING FOR A CHANCE FOR SNOW TO CHANGE TO
FREEZING DRIZZLE FOR ALL AS MOISTURE IS DEPLETED FROM THE FAVORABLE
CRYSTAL GROWTH ZONE. THE LACK OF MOISTURE DEPTH SHOULD GREATLY LIMIT
SNOW AND ICE ACCUMULATIONS. CONTINUE TO SEE LITTLE REASON TO DIVERGE
FROM CONTINUITY AND MAINTAIN GENERAL SNOW ACCUMULATIONS AN INCH OR
LESS OVERNIGHT...WITH ICE ACCUMULATIONS LESS THAN A TENTH OF AN INCH.
DESPITE THE LIMITED ACCUMULATIONS...STILL EXPECT ISSUES TO DEVELOP
ON UNTREATED SURFACES. ADVISORIES WILL REMAIN IN PLACE.

THE COLUMN WILL CONTINUE TO WARM WITH AN EVENTUAL CHANGE OVER TO
DRIZZLE...LIKELY BETWEEN 09Z AND 15Z MONDAY...THE EXCEPTION MAY BE
ACROSS PORTIONS OF THE NORTH COUNTRY WHERE THE PRECIPITATION MAY
STAY ALL SNOW ESPECIALLY OVER THE TUG HILL. THIS MAY ALLOW FOR AN
ADDITIONAL INCH OR TWO OF NEW SNOW ACCUMULATION THROUGHOUT THE DAY
MONDAY. AS THE SYSTEM SLIDES TO THE EAST MONDAY...THE REGION WILL BE
STUCK UNDER A SUBSIDENCE INVERSION...WHICH SHOULD KEEP LOW CLOUDS
AND LIGHT PRECIPITATION LINGERING.

COLDER AIR WILL BUILD INTO THE AREA BY LATE IN THE DAY WITH THE COLD
FRONTAL PASSAGE. ANY LINGERING LIQUID PRECIPITATION WILL CHANGE BACK
OVER TO SNOW. THERE IS SOME MODEL SUGGESTION THAT A DEVELOPING
SOUTHWEST FLOW MAY FOCUS SOME LAKE ENHANCED SNOW INTO THE BUFFALO
AREA TOWARD MONDAY EVENING.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
DURING THE COURSE OF MONDAY NIGHT...THE COMPLEX LOW PRESSURE SYSTEM
RESPONSIBLE FOR TONIGHT/S AND MONDAY/S MIXED PRECIPITATION WILL
QUICKLY EXIT OFF TO THE NORTHEAST...WITH SURFACE-BASED RIDGING AND
DRIER AIR BUILDING NORTHEASTWARD ACROSS THE OHIO VALLEY AND LOWER
GREAT LAKES IN ITS WAKE. MEANWHILE ALOFT...UPPER LEVEL TROUGHING
WILL CONTINUE TO DIG ACROSS THE GREAT LAKES AND NORTHEAST...WITH
STEADY COLD AIR ADVECTION PUSHING 850 MB TEMPS FROM -8C TO AROUND
-14C.

WHILE THE INCREASINGLY COLDER AIRMASS ALOFT WILL BE FAVORABLE FOR A
LAKE RESPONSE NORTHEAST AND THEN EAST OF THE LAKES AS THE LOW LEVEL
FLOW QUICKLY VEERS MORE WESTERLY...ANY SUCH RESPONSE STILL APPEARS
AS IF IT WILL BE GREATLY HINDERED BY A RELATIVELY LOW CAP AT AROUND
4-5 KFT AND THE LACK OF A SIGNIFICANT DENDRITIC SNOW GROWTH REGION
BELOW THIS INVERSION...WHICH SHOULD TEND TO KEEP ANY ACTIVITY LIGHT
AND MORE SCATTERED IN NATURE. FOR THIS REASON...HAVE CONTINUED TO
CONFINE POPS TO THE CHANCE RANGE IN THE FAVORED AREAS DOWNWIND OF
THE LAKES...WITH JUST A FEW LEFTOVER FLURRIES POSSIBLE ELSEWHERE AS
OVERALL SYNOPTIC SCALE MOISTURE DIMINISHES. TEMPERATURE-WISE...
READINGS WILL TREND COLDER UNDER THE COLD AIR ADVECTION PATTERN...
WITH OVERNIGHT LOWS DIPPING INTO THE LOWER TO MID 20S.

ON TUESDAY...THE AXIS OF THE SURFACE RIDGE WILL SLIP SOUTHEASTWARD
INTO THE MID ATLANTIC STATES...WHILE A MODEST SURFACE WAVE DEVELOPS
EASTWARD ACROSS THE UPPER GREAT LAKES...IN RESPONSE TO A DECENT
MID-LEVEL SHORTWAVE SLIDING THROUGH THE BASE OF THE BURGEONING
PARENT UPPER LEVEL TROUGH. OVER TIME...WINDS SHOULD BACK TO MORE OF
A WEST-SOUTHWESTERLY ORIENTATION ACROSS THE LOWER GREAT LAKES IN
ADVANCE OF THE APPROACHING SURFACE TROUGH...WHICH SHOULD EVENTUALLY
SEND THE STILL-LIMITED LAKE SNOWS BACK NORTHWARD INTO THE BUFFALO
AND WATERTOWN AREAS. DURING THE AFTERNOON...THESE MAY BEGIN TO PICK
UP A LITTLE IN ORGANIZATION AND INTENSITY AS THE APPROACHING TROUGH
ACTS TO LIFT THE CAP SOMEWHAT WHILE ALSO BRINGING AN INCREASE IN
BACKGROUND SYNOPTIC-SCALE MOISTURE...BOTH THE AMOUNT AND RATE OF
THIS IMPROVEMENT IN THE OVERALL THERMODYNAMIC SETUP REMAINS IN
QUESTION GIVEN CONFLICTING SIGNALS IN THE SHORT TERM GUIDANCE. WITH
THIS IN MIND...FOR NOW FEEL IT BEST TO AIM A LITTLE CONSERVATIVE AND
REFLECT THIS POSSIBILITY BY BUMPING POPS UP TO LIKELY NORTHEAST OF
THE LAKES...WHERE SOME MINOR ACCUMS OF AN INCH OR SO APPEAR TO BE
POSSIBLE.

TUESDAY NIGHT...THE AFOREMENTIONED SHORTWAVE AND ATTENDANT SURFACE
REFLECTION WILL QUICKLY SLIDE EAST ACROSS SOUTHERN ONTARIO AND
QUEBEC...WITH OUR LOW LEVEL FLOW CONSEQUENTLY VEERING BACK TO MORE
OF A WESTERLY ORIENTATION DURING THE EVENING. THIS WILL SEND THE
LAKE SNOWS BACK SOUTHWARD INTO THE TYPICALLY FAVORED SNOWBELTS EAST
OF THE LAKES...WHILE A CONTINUED INCREASE IN LARGER-SCALE MOISTURE
AND INVERSION HEIGHTS/LAKE EQLS ALLOWS THIS ACTIVITY TO BECOME
INCREASINGLY BETTER ORGANIZED EAST OF BOTH LAKES...AND POTENTIALLY
SIGNIFICANT IN NATURE.

AFTER THIS...THE BULK OF THE AVAILABLE GUIDANCE IS IN FAIRLY GOOD
AGREEMENT ON A GENERAL WESTERLY FLOW OF PROGRESSIVELY COLDER AIR
CONTINUING ACROSS THE LOWER GREAT LAKES THROUGH THE END OF THE
PERIOD...WITH 850 MB TEMPS FALLING TO AROUND -18C BY THURSDAY
MORNING. WITH OVERALL SYNOPTIC MOISTURE AND OTHER THERMODYNAMIC
PARAMETERS CONTINUING TO LOOK FAVORABLE THROUGH THIS TIME FRAME...
POTENTIALLY SIGNIFICANT LAKE SNOWS SHOULD CONTINUE EAST OF THE
LAKES...AND APPEAR AS IF THEY WILL LINGER INTO THE EARLY STAGES OF
THE LONG TERM PERIOD AS WELL. WITH ALL OF THIS IN MIND...WE HAVE
HOISTED LAKE EFFECT SNOW WATCHES FOR TUESDAY NIGHT THROUGH THURSDAY
FOR THE SOUTHERN ERIE/WYOMING/CHAUTAUQUA/CATTARAUGUS COUNTY CORRIDOR
EAST OF LAKE ERIE...AND FOR OSWEGO/JEFFERSON/LEWIS COUNTIES EAST OF
LAKE ONTARIO. WHILE IT SHOULD BE NOTED THAT THE 12Z NAM DOES SUGGEST
SOME POTENTIAL FOR THE LAKE SNOWS TO LIFT BACK NORTHWARD FOR A TIME
ON WEDNESDAY AND IMPACT THE BUFFALO/WATERTOWN AREAS...AT THIS POINT
THIS SOLUTION IS AN OUTLIER WITH THE NORMALLY MORE RELIABLE GFS/
GEM/ECMWF ALL SUGGESTING THAT THE FLOW WILL REMAIN MORE WESTERLY...
WHICH WOULD KEEP THE LAKE SNOWS CONFINED TO AREAS FURTHER TO THE
SOUTH.

OUTSIDE OF THE MAIN LAKE EFFECT AREAS...TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT SHOULD BE COLD AND MAINLY DRY WITH JUST THE CHANCE
OF SOME PASSING FLURRIES OR LIGHT SNOW SHOWERS. GIVEN THE OVERALL
COLD AIR ADVECTION REGIME...TEMPS SHOULD CONTINUE TO LOWER...WITH
DAYTIME HIGHS DROPPING TO THE LOWER TO MID 20S BY WEDNESDAY...AND
NIGHTTIME LOWS FALLING TO THE 5-15 RANGE BY WEDNESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS MENTIONED ABOVE...ON THURSDAY POTENTIALLY SIGNIFICANT LAKE SNOWS
SHOULD CONTINUE EAST OF THE LAKES AS A GENERAL WESTERLY FLOW OF COLD
AIR CONTINUES ACROSS THE REGION. WITH SOME OF THE MEDIUM RANGE
GUIDANCE STILL SUGGESTING THAT BRIEF MINOR FLUCTUATIONS IN THE LOW
LEVEL FLOW ARE POSSIBLE ON THURSDAY...IT IS POSSIBLE THAT THE
PLACEMENT OF THE LAKE SNOWS MAY VARY SOME THROUGH THE DAY...SO HAVE
ELECTED TO INDICATE BROADER REGIONS OF SOMEWHAT LOWER (HIGH CHANCE
TO LOW LIKELY) POPS DOWNWIND OF THE LAKES. OUTSIDE OF THESE AREAS...
COLDER THAN NORMAL CONDITIONS WILL PERSIST ALONG WITH A MORE GENERAL
LOW CHANCE OF SOME SNOW SHOWERS.

AFTERWARDS...CONSIDERABLE DISCREPANCIES PERSIST WITH RESPECT TO BOTH
THE TIMING AND AMPLITUDE OF THE NEXT NOTEWORTHY SURFACE TROUGH
LATE IN THE WEEK AND NEXT WEEKEND...WITH THE 12Z OPERATIONAL
GUIDANCE ALL OVER THE MAP ON THE HANDLING OF THIS FEATURE. GIVEN
THE ENSUING LARGE DEGREE OF FORECAST UNCERTAINTY WITH RESPECT TO
BOTH PRECIP POTENTIAL AND THE TEMPERATURE FORECAST...HAVE ELECTED
TO LEAN TOWARD WPC GUIDANCE AND THE MORE CONSISTENT ECMWF FOR THE
REST OF THE FORECAST PERIOD. IN THE FORECAST...THIS IS REFLECTED
BY CONTINUED BELOW NORMAL TEMPS...AS WELL AS MORE BROADBRUSH POPS
THAT FALL OFF THROUGH THE CHANCE RANGE LATE IN THE WEEK...THEN TO
SLIGHT CHANCE FOR NEXT WEEKEND.

&&

.AVIATION /04Z MONDAY THROUGH FRIDAY/...
FOR THE 00Z TAFS...VFR FLIGHT CONDITIONS TO START THE PERIOD WILL
QUICKLY DETERIORATE THIS EVENING...FIRST AT THE KJHW TERMINAL...AND
THEN PROGRESSIVELY NORTHWARD. WILL BEGIN THE TAFS WITH A SEVERAL
HOUR OF LIGHT SNOW...THEN PRECIPITATION WILL CHANGE TO A
SNOW/FREEZING DRIZZLE AND PERHAPS ALL FREEZING DRIZZLE BEFORE
CHANGING TO DRIZZLE AND ENDING TOMORROW. LIGHT PRECIPITATION IS
EXPECTED TO LINGER ACROSS THE NORTH COUNTRY INCLUDING THE KART
AIRFIELD...POSSIBLY THROUGH THE END OF THE TAF CYCLE.

CIGS WILL LOWER TO IFR ACROSS THE SOUTHERN TIER AND NORTH COUNTRY
LATER IN THE TAF CYCLE. AS WINDS VEER TO MORE SOUTHERLY OVERNIGHT
CONDITIONS AT THE KIAG/KBUF AND KROC AIRFIELDS WILL LIKELY REMAIN
MVFR...THOUGH BRIEF PERIODS OF IFR VSBYS IN SNOW/FREEZING DRIZZLE
CANNOT BE RULED OUT.

A LLJ TOMORROW WILL TRACK ACROSS THE GENESEE VALLEY AND INTO THE
FINGER LAKES AND NORTH COUNTRY REGIONS. WILL HAVE A PERIOD OF LLWS
IN THE TAFS AT THE CORRESPONDING SITES AND AS THIS JET ADVANCES
EASTWARD AND SURFACE WINDS INCREASE...WILL REMOVE THE NEED FOR LLWS.
SOME LIGHT LAKE EFFECT SNOW SHOWERS ARE POSSIBLE VERY LATE IN THE
TAF PERIOD NEAR THE KBUF AIRFIELD.

OUTLOOK...
MONDAY NIGHT...MVFR/VFR WITH LAKE EFFECT SNOW SHOWERS LIKELY.
TUESDAY THROUGH FRIDAY...MAINLY VFR WITH LOCALIZED IFR IN LAKE
EFFECT SNOW EAST OF THE LAKES.

&&

.MARINE...
SOUTHEASTERLY WINDS WILL INCREASE TONIGHT AS A WARM FRONT LIFTS
ACROSS THE REGION. WINDS WILL VEER TO THE SOUTHWEST MONDAY AND
FRESHEN TO AROUND 30 KNOTS AS A COLD FRONT CROSSES THE LAKES. THE
PASSAGE OF THE COLD FRONT WILL BRING AN EXTENDED PERIOD OF ADVISORY
LEVEL WINDS AND WAVES WITH GALES ALSO POSSIBLE TUESDAY INTO
WEDNESDAY. HIGH PRESSURE NOSING ACROSS THE LAKES MAY BRING A BRIEF
RESPITE TO THE WINDS/WAVES ON THURSDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
NY...LAKE EFFECT SNOW WATCH FROM TUESDAY EVENING THROUGH THURSDAY
     AFTERNOON FOR NYZ006>008-012-019-020-085.
     WINTER WEATHER ADVISORY UNTIL 2 PM EST MONDAY FOR NYZ006>008.
     WINTER WEATHER ADVISORY UNTIL 11 AM EST MONDAY FOR NYZ001>005-
     010>014-085.
     WINTER WEATHER ADVISORY UNTIL 1 PM EST MONDAY FOR NYZ019>021.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 6 PM EST WEDNESDAY
         FOR LEZ020.
         SMALL CRAFT ADVISORY FROM 7 AM MONDAY TO 6 PM EST
         WEDNESDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 6 PM EST
         WEDNESDAY FOR LOZ030.
         SMALL CRAFT ADVISORY FROM 4 PM MONDAY TO 6 PM EST
         WEDNESDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY FROM 1 PM MONDAY TO 6 PM EST
         WEDNESDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO 6 PM EST
         WEDNESDAY FOR LOZ045.
         SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 7 AM EST
         WEDNESDAY FOR SLZ022-024.
-- End Changed Discussion --

&&

$$

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