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000
FXUS61 KBUF 092016
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
316 PM EST MON DEC 9 2013

.SYNOPSIS...
SOME LIMITED LAKE EFFECT SNOW SHOWERS WILL DEVELOP EAST OF THE LAKES
TONIGHT AND TUESDAY WITH SOME MINOR ACCUMULATIONS POSSIBLE. A
WESTERLY FLOW OF COLDER AIR WILL THEN SET THE STAGE FOR SIGNIFICANT
LAKE EFFECT SNOW EAST OF THE LAKES TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT. SOME LAKE EFFECT SNOW WILL CONTINUE THROUGH THE END OF THE
WEEK BEFORE AN AREA OF LOW PRESSURE POTENTIALLY BRINGS A MORE
WIDESPREAD GENERAL SNOWFALL THIS WEEKEND. TEMPERATURES WILL BE BELOW
AVERAGE THE ENTIRE PERIOD.

&&

.NEAR TERM /THROUGH TUESDAY/...
THE SURFACE COLD FRONT IS CROSSING THE EASTERN LAKE ONTARIO REGION
AT MID AFTERNOON WITH A BRIEF PERIOD OF LAKE ENHANCED RAIN AND WET
SNOW SHOWERS. BEHIND THE FRONT A FEW FLURRIES AND SPRINKLES CONTINUE
ACROSS WESTERN NY WITH JUST A HINT OF LAKE ENHANCEMENT NEAR BUFFALO.
EXPECT THIS TO CONTINUE THROUGH EARLY EVENING WITH A FEW SPRINKLES
AND FLURRIES POSSIBLE...WITH A LITTLE BETTER CONCENTRATION NORTHEAST
OF BOTH LAKES. TEMPERATURES WILL SLOWLY PULL BACK BELOW FREEZING
THROUGH THE EVENING HOURS. RECENT TRENDS IN RADAR AND SURFACE OBS
SUGGEST THAT THE DRIZZLE POTENTIAL HAS ENDED WITH MOISTURE NOW DEEP
ENOUGH TO SUPPORT ICE NUCLEI WITHIN THE CLOUD LAYER.

TONIGHT THROUGH TUESDAY MOST OF THE WEATHER WILL BE LAKE EFFECT IN
NATURE WITH ONE MINOR EXCEPTION. ANOTHER FRONTAL WAVE WILL PASS
THROUGH THE MID ATLANTIC STATES TONIGHT. THE NORTHERN EDGE OF THIS
FEATURE MAY CLIP THE SOUTHERN TIER LATE TONIGHT AND EARLY TUESDAY
MORNING. UPPER LEVEL DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A
STRONG 180+ KNOT UPPER LEVEL JET IN ADDITION TO SOME WEAK MID LEVEL
FRONTOGENESIS WILL MOVE ACROSS PA AND CLIP THE SOUTHERN TIER. THIS
WILL PRODUCE A PERIOD OF ASCENT CENTERED IN THE MID LEVELS. AN
EXTENSIVE DRY LAYER BENEATH THIS REGION OF LIFT WILL SUPPORT PLENTY
OF SUB-CLOUD EVAPORATION...SO JUST EXPECT A FEW SCATTERED LIGHT SNOW
SHOWERS NEAR THE PA STATE LINE LATE TONIGHT AND EARLY TUESDAY
INDEPENDENT OF LAKE EFFECT.

NOW FOR LAKE EFFECT POTENTIAL.

OFF LAKE ERIE...SOUTHWEST FLOW THIS EVENING WILL BECOME MORE WSW
OVERNIGHT AND BRIEFLY WESTERLY TUESDAY MORNING. INSTABILITY WILL
REMAIN VERY LIMITED GIVEN THE MARGINAL TEMPERATURES AND DRY AIR
ALOFT...WITH LAKE INDUCED EQUILIBRIUM LEVELS ONLY RISING TO AROUND
6K FEET. THIS WILL ONLY SUPPORT LIGHT SNOW SHOWERS OVERNIGHT WHICH
WILL START THIS EVENING NEAR THE BUFFALO SOUTHTOWNS THEN DRIFT
SLOWLY SOUTH INTO THE SOUTHERN TIER BY LATE TONIGHT. AMOUNTS SHOULD
BE LIMITED TO AROUND AN INCH FROM THE BOSTON HILLS AND WESTERN
WYOMING COUNTY INTO MAINLY THE CHAUTAUQUA RIDGE AND NORTHERN
CATTARAUGUS COUNTY.

ANY REMAINING LAKE EFFECT SHOULD STAY DISORGANIZED THROUGH THE
MORNING ACROSS THE WESTERN SOUTHERN TIER AS A NARROW SURFACE RIDGE
BUILDS OVER LAKE ERIE. SOME MINOR ADDITIONAL AMOUNTS OF LESS THAN AN
INCH ARE POSSIBLE IN A FEW SPOTS. DURING THE AFTERNOON A MID LEVEL
SHORTWAVE AND ASSOCIATED SURFACE COLD FRONT WILL APPROACH FROM THE
WEST. THIS WILL FORCE BOUNDARY LAYER WINDS TO BACK TO THE
SOUTHWEST...CARRYING A WEAK BAND OF LAKE EFFECT SNOW SHOWERS NORTH
INTO BUFFALO AND GENESEE COUNTY BY MID AFTERNOON. THIS BAND SHOULD
INTENSIFY DURING THE LATE AFTERNOON AS LOW LEVEL CONVERGENCE
INCREASES WITH THE APPROACH OF THE SURFACE COLD FRONT...AND ALSO AS
INSTABILITY RAPIDLY INCREASES. THIS MAY PRODUCE AN INCH OR SO OF
ACCUMULATION FROM BUFFALO TO BATAVIA DURING THE LATE AFTERNOON WITH
ADDITIONAL AMOUNTS EXPECTED TUESDAY EVENING.

OFF LAKE ONTARIO...SOUTHWEST FLOW THIS EVENING WILL BECOME MORE WSW
OVERNIGHT AND EVENTUALLY WESTERLY TUESDAY MORNING. THIS WILL CARRY
SOME LIMITED LAKE EFFECT SNOW SHOWERS FROM NEAR WATERTOWN THIS
EVENING SOUTH ACROSS THE TUG HILL PLATEAU DURING THE OVERNIGHT. THE
BAND SHOULD REACH THE SOUTHERNMOST EXTENT TUESDAY MORNING ACROSS
NORTHERN OSWEGO COUNTY AND THE TUG HILL. LAKE INDUCED EQUILIBRIUM
LEVELS REMAIN BELOW 6K FEET THROUGH THE EARLY OVERNIGHT...BUT DO
PEAK AT 7-8K FEET TUESDAY MORNING. EXPECT THE BAND TO REMAIN WEAK
WITH JUST SCATTERED LIGHT SNOW SHOWERS THROUGH THE EARLY
OVERNIGHT...BUT SHOULD THEN PICK UP A LITTLE IN ORGANIZATION AND
INTENSITY BY TUESDAY MORNING MAINLY FROM NORTHERN OSWEGO COUNTY TO
THE TUG HILL. AN ADDED BOOST FROM UPSLOPE FLOW MAY PRODUCE 2-4
INCHES ON THE TUG HILL TONIGHT INTO TUESDAY MORNING WITH AN INCH OR
TWO ELSEWHERE MAINLY SOUTH OF WATERTOWN AND NORTH OF PARISH EAST
ACROSS LEWIS COUNTY.

TUESDAY AFTERNOON A WEAK BAND OF SNOW SHOWERS WILL LIFT NORTH
TOWARDS WATERTOWN AND THE NORTHERN HALF OF LEWIS COUNTY. THIS BAND
SHOULD BEGIN TO INTENSIFY SOME AT THE END OF THE DAY WITH THE
APPROACH OF THE COLD FRONT...WITH THE MORE SIGNIFICANT SNOW
DEVELOPING THEREAFTER.

OUTSIDE OF LAKE EFFECT AREAS IT WILL BE MAINLY DRY WITH JUST A FEW
FLURRIES POSSIBLE. 850MB TEMPS DROPPING TO AROUND -16C ON TUESDAY
WILL ONLY SUPPORT HIGHS IN THE MID 20S AT BEST ACROSS LOWER
ELEVATIONS WITH LOWER 20S ACROSS HIGHER TERRAIN.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
EXTENDED PERIOD OF SIGNIFICANT LAKE EFFECT SNOWS EXPECTED DURING THE
MID WEEK PERIOD.

LAKE EFFECT SNOWS WILL PICK UP IN INTENSITY TUESDAY NIGHT AND
WEDNESDAY MORNING WITH COLDER AIR CONTINUING TO ADVECT INTO THE
LOWER GREAT LAKES. LAKE BAND INITIALLY FOCUSED INTO THE BUFFALO
SOUTHTOWNS WILL SHIFT SOUTH DURING TUESDAY NIGHT...BEHIND THE
PASSAGE OF A TROUGH AS THE STEERING FLOW VEERS TO WESTERLY.
PLENTY OF OVER-LAKE INSTABILITY WITH 850 MB TEMPERATURES NEAR
-16C...ALONG WITH INVERSION HEIGHTS WELL ABOVE 10K FEET SHOULD ALLOW
FOR AN IMPRESSIVE LAKE PLUME TO DEVELOP EAST OF LAKE ONTARIO...WITH
SOME LOCATIONS ON THE TUG HILL PERHAPS SURPASSING A FOOT.
INSTABILITY AND FETCH NOT QUITE AS IMPRESSIVE OFF LAKE ERIE...BUT
STILL COULD SEE AMOUNTS EASILY EXCEEDING 6 INCHES...ESPECIALLY ALONG
THE CHAUTAUQUA RIDGE.

MODEL SUGGESTION IS TO WEAKEN LAKE ACTIVITY A BIT DURING WEDNESDAY
AHEAD OF SECONDARY SURFACE TROUGH/ARCTIC BOUNDARY. SHEAR PROFILES
SUGGESTING LAKE SNOWS WILL BE MEANDERING NORTH AND SOUTH THROUGH THE
DAY...WHICH MAKES IT HARD TO DETERMINE WHICH AREAS WILL BE THE FOCUS
FOR THE HEAVIEST AND MORE PERSISTENT SNOWS. ALTHOUGH SOME AREAS WILL
LIKELY SEE CONTINUED BURSTS FOR HEAVY SNOW SOUTH OF THE BUFFALO AND
WATERTOWN AREAS.

THE TROUGH/FRONT LOOK TO CROSS THE LOWER LAKES WEDNESDAY NIGHT WITH
A REINFORCING SHOT COLD AIR WHICH WILL BRING AN UPTICK TO THE LAKE
EFFECT SNOW BANDS. STEERING FLOW TURNS NORTHWESTERLY BEHIND THE
PASSAGE FOR WEDNESDAY NIGHT AND THURSDAY. THIS WILL CONTINUE TO
FOCUS HEAVY LAKE BANDS ACROSS THE CHAUTAUQUA RIDGE...WHILE
DEVELOPING MORE MULTIPLE BAND CONFIGURATION ALONG THE SOUTH SHORE OF
LAKE ONTARIO.

OUTSIDE OF LAKE EFFECT...IT WILL BE COLD AND WINDY WITH SCATTERED
WIND DRIVEN SNOW SHOWERS. THE CONTINUED COLD AIR ADVECTION IN
THE WESTERLY FLOW WILL KEEP TEMPERATURE BELOW NORMAL WITH DAYTIME
HIGHS IN THE LOWER TO MID 20S...AND OVERNIGHT LOWS IN THE TEENS AND
SINGLE DIGITS. WIND CHILLS NEAR ZERO OR IN THE NEGATIVE SINGLE
DIGITS.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
CONSIDERABLE DISCREPANCIES PERSIST TO END THE WORK WEEK RIGHT
THROUGH THE WEEKEND AS LATEST MEDIUM RANGE CONTINUE TO DIFFER ON THE
HANDLING OF THE DEVELOPING BAROCLINIC ZONE ACROSS THE GREAT LAKES.
THIS SCENARIO WOULD SET THE STAGE FOR A PROLONGED PERIOD OF SNOW
SHOWERS...WITH AT LEAST SOME LAKE CONTRIBUTION AT TIMES...ALTHOUGH
THE ACTUAL MEAN FLOW IS TOO HARD TO FORECAST AT THIS TIME. THEREFORE
HAVE MAINTAINED GENERIC CHANCE PROBABILITIES. TEMPERATURES ARE
EXPECTED TO REMAIN COLD WITH HIGHS IN THE UPPER TEENS TO MID 20S AND
LOWS IN THE UPPER SINGLE DIGITS AND TEENS.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
AREAS OF DRIZZLE WILL CONTINUE THROUGH THE AFTERNOON ACROSS WESTERN
NY AND SPREAD EAST ACROSS CENTRAL NY AND THE NORTH COUNTRY THROUGH
MID AFTERNOON. SOME WET SNOWFLAKES MAY ALSO MIX IN AT TIMES. VSBY
WILL BE MAINLY VFR...ALTHOUGH SOME MVFR IS POSSIBLE IN A FEW SPOTS
WITHIN MORE PERSISTENT DRIZZLE. CIGS WILL BE MAINLY MVFR ACROSS THE
ENTIRE REGION THIS AFTERNOON THROUGH THIS EVENING WITH AREAS OF IFR
ACROSS HIGHER TERRAIN.

CIGS SHOULD SLOWLY COME UP SOME LATE TONIGHT AND TUESDAY WITH LOWER
ELEVATIONS TRENDING TOWARDS VFR WITH MVFR LINGERING ACROSS HIGHER
TERRAIN. WITHIN LAKE BANDS MVFR CIGS WILL BE MOST LIKELY...WITH SOME
SPOTTY IFR ACROSS HIGHER TERRAIN. EXPECT LAKE EFFECT SNOW SHOWERS TO
SLOWLY INCREASE OVERNIGHT INTO TUESDAY MORNING EAST OF THE LAKES.
THIS WILL MISS MOST OF THE TAF SITES...EXCEPT NEAR KJHW WHERE MVFR
OR EVEN IFR WILL BECOME MORE LIKELY LATE TONIGHT INTO TUESDAY
MORNING.

LATER TUESDAY AFTERNOON LAKE EFFECT WILL LIFT NORTH TOWARDS KBUF AND
KART WITH A BRIEF PERIOD OF IFR LIKELY FROM ROUGHLY 22Z-01Z.

OUTLOOK...
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...VFR EXCEPT AREAS OF IFR EAST
OF THE LAKES IN HEAVY LAKE EFFECT SNOW.
THURSDAY...VFR EXCEPT MVFR/IFR IN LAKE EFFECT SNOW SHOWERS SOUTHEAST
OF THE LAKES.
FRIDAY...VFR EXCEPT MVFR/IFR IN LAKE EFFECT SNOW SHOWERS EAST OF THE
LAKES.
SATURDAY...MVFR/IFR WITH A CHANCE OF SNOW.

&&

.MARINE...
A DEEPENING AREA OF LOW PRESSURE WILL MOVE PAST THE SOUTHERN TIP OF
JAMES BAY THIS EVENING THEN ACROSS QUEBEC TONIGHT AND PRODUCE STRONG
WINDS ACROSS THE LOWER LAKES. MARGINAL SOUTHWEST GALES WILL CONTINUE
ON LAKE ERIE THROUGH EARLY EVENING BEFORE SLOWLY DIMINISHING
OVERNIGHT. ON LAKE ONTARIO EXPECT MARGINAL GALES TO CONTINUE THROUGH
MUCH OF THE NIGHT BEFORE DIMINISHING A LITTLE BY TUESDAY MORNING.

WESTERLY WINDS WILL INCREASE AGAIN TUESDAY NIGHT AND WEDNESDAY WITH
GALES POSSIBLE ON BOTH LAKES ONCE AGAIN.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING FROM 6 PM TUESDAY TO 4 AM EST
     THURSDAY FOR NYZ006>008-012-019-020-085.
     LAKE EFFECT SNOW ADVISORY FROM 4 PM TUESDAY TO 1 AM EST
     WEDNESDAY FOR NYZ010-011.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR LEZ020.
         GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR
         LOZ030.
         GALE WARNING UNTIL 4 AM EST TUESDAY FOR LOZ042>045-062>065.
         SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR
         SLZ022-024.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...HITCHCOCK
MARINE...HITCHCOCK