Lake Effect Snow Advisory 20, NWS Buffalo, NY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
335 PM EST SUN NOV 16 2014

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL PASS ACROSS THE AREA LATER TONIGHT AND
MONDAY PRODUCING A WIDESPREAD SNOWFALL. A REINFORCING BLAST OF
COLDER AIR MONDAY NIGHT WILL SET THE STAGE FOR SIGNIFICANT LAKE
EFFECT SNOW ACCUMULATIONS MONDAY NIGHT THROUGH WEDNESDAY...WITH
ADDITIONAL LAKE EFFECT SNOW AND BELOW NORMAL TEMPERATURES LIKELY
TOWARDS THE END OF THE WORK WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
HAVE ISSUED WINTER WEATHER ADVISORIES WITH THIS FORECAST PACKAGE FOR
MUCH OF THE FORECAST AREA OVERNIGHT THROUGH THE DAY ON MONDAY FOR
SNOWFALL...WITH THE EXCEPTION OF ROCHESTER AND ACROSS THE NORTHERN
FINGER LAKES.

STRENGTHENING SOUTHWESTERLY FLOW ALOFT OVER THE FORECAST OVERNIGHT
WILL RESULT IN A TIGHTENING THERMAL GRADIENT OVER THE AREA. WARM AIR
ADVECTION AND OVERRUNNING WILL DEVELOP A WIDESPREAD STRATIFORM
PRECIPITATION EVENT THAT WILL CONTINUE THROUGH THE DAY MONDAY. THE
SHORTWAVE TROUGH CURRENTLY SEEN ON WATER VAPOR IMAGERY NEAR THE
TEXAS PAN HANDLE WILL EJECT ACROSS THE FORECAST AREA MONDAY MORNING.
THIS WAVE WILL HELP TO VEER THE SURFACE WINDS TO THE SOUTHEAST AHEAD
OF THE WAVE...AND INCREASE THE WARM ADVECTION ACROSS CENTRAL NEW
YORK STATE. THIS SHORTWAVE PASSAGE WILL FURTHER ENHANCE THE QG
FORCING OVER THE FORECAST AREA...HOWEVER THE STRONG SURGE OF WARM
AIR AHEAD OF THE WAVE WILL COMPLICATE THE PRECIPITATION TYPE
FORECAST ACROSS CENTRAL NEW YORK.

WITH REGARD TO PRECIPITATION INTENSITY AND TYPE...THE HEAVIEST
PRECIPITATION RATES ARE EXPECTED BETWEEN 12Z AND 18Z MONDAY...WHICH
COINCIDES WITH THE SHORTWAVE PASSAGES. HOWEVER...THIS IS ALSO THE
TIME THAT A WARM NOSE OF 0C TO +2C AIR ALOFT PUSHES FROM GENESEE
VALLEY AREA TO THE EAST. EXPECT LOCATIONS WEST OF THE GENESEE
VALLEY...INCLUDING BUFFALO AND JAMESTOWN WILL REMAIN ALL SNOW
THROUGH THE EVENT. HOWEVER...AREAS FROM ROCHESTER ACROSS THE
NORTHERN FINGER LAKES WILL LIKELY START AS SNOW OVERNIGHT...BUT
TRANSITION TO A WINTERY MIX AFTER SUNRISE...AND POSSIBLY TO ALL RAIN
FOR A PERIOD OF TIME DURING THE DAY MONDAY. THIS SOLUTION WILL MEAN
LOWER SNOW AMOUNTS ACROSS THE MIXED PRECIPITATION AREA...AND IMPACTS
WILL LIKELY BE MUCH LESS. FARTHER EAST ACROSS THE NORTH
COUNTRY...THE WARM SURGE OF AIR IS CURRENTLY EXPECT TO BARELY CLIP
THE SOUTHERN PORTIONS OF THE NORTH COUNTRY...THUS EXPECT
PRECIPITATION TO REMAIN MOSTLY SNOW. GIVEN THE WARMER AIR ALOFT...DO
NOT EXPECT MUCH IF ANY LAKE ENHANCEMENT TO THIS SYNOPTIC EVENT.

AS FOR SNOW AMOUNTS...EXPECT TO SEE MAINLY 3 TO 6 INCHES ACROSS
WESTERN NEW YORK...FOR AREAS WEST OF THE GENESEE VALLEY INCLUDING
BUFFALO AND JAMESTOWN. ROCHESTER AND THE NORTHERN FINGER LAKES WILL
LIKELY PICK UP AN INCH OR SO OF SNOW OVERNIGHT...BUT THEN WILL BE
LIMITED TO AN INCH OR LESS DURING THE DAY MONDAY DUE TO THE
INFLUENCE FROM THE WARMER AIR. ACROSS THE NORTH COUNTRY...3 TO 7
INCHES...AMOUNTS WILL BE SOMEWHAT ELEVATION DEPENDENT WITH HIGHER
AMOUNTS ACROSS THE TUG HILL PLATEAU.

TEMPERATURES WILL BE FAIRLY STEADY WITHIN A FEW DEGREES OF FREEZING
ACROSS WESTERN NEW YORK OVERNIGHT TONIGHT AND INTO MONDAY.
TEMPERATURES ACROSS CENTRAL NEW YORK WILL SEE A DAYTIME RISE INTO
THE UPPER 30S ON MONDAY FROM THE INFLUENCE OF THE WARMER AIR. WINDS
WILL PICK UP OUT OF THE SOUTHWEST LATE MONDAY BEHIND THE SHORTWAVE.

AS THE SYNOPTIC EVENT WINDS DOWN MONDAY AFTERNOON/EVENING...WE WILL
TRANSITION TO A SIGNIFICANT LAKE EFFECT SNOW EVENT.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
...MAJOR AND VERY DISRUPTIVE LAKE EFFECT SNOW EVENT LIKELY EAST AND
NORTHEAST OF BOTH LAKES ERIE AND ONTARIO...

THE STAGE IS SET FOR A MAJOR LAKE EFFECT SNOW EVENT STARTING MONDAY
EVENING AND LASTING THROUGH THE FIRST HALF OF WEDNESDAY. THE
SYNOPTIC SNOW WILL BE JUST ABOUT OVER BY EARLY MONDAY EVENING...WITH
JUST A FEW SNOW SHOWERS LEFT EAST OF LAKE ONTARIO WHICH WILL QUICKLY
EXIT. THIS WILL LEAVE MAINLY LAKE EFFECT TO DEAL WITH THROUGH THE
SHORT TERM PERIOD. A MID LEVEL TROUGH MAY BRING A FEW LIGHT
SCATTERED SNOW SHOWERS OUTSIDE OF LAKE EFFECT AREAS LATER TUESDAY
AND TUESDAY EVENING.

FROM A SYNOPTIC STANDPOINT...A MID LEVEL CUTOFF LOW WILL QUICKLY
DEVELOP JUST EAST OF LAKE SUPERIOR MONDAY EVENING THEN MOVE EAST
ACROSS CENTRAL QUEBEC THROUGH TUESDAY AFTERNOON WITH A RAPIDLY
DEEPENING SURFACE LOW TAKING A SIMILAR TRACK. A STRONG PUSH OF
ARCTIC AIR WILL WRAP AROUND THE MID LEVEL LOW...MOVING ACROSS THE
OHIO VALLEY AND COMING AT THE LOWER LAKES FROM THE SOUTHWEST. THIS
IS A HALLMARK OF A MAJOR SINGLE BAND EVENT. THE POSITION OF THE
850MB CLOSED LOW FROM MONDAY NIGHT THROUGH THE FIRST HALF OF TUESDAY
FAVORS A SOUTHWEST FLOW EVENT OFF BOTH LAKES PER COMPARISON TO OUR
ANALOG CHARTS OF THE PAST 15 YEARS OF LAKE EFFECT EVENTS. BY LATE
TUESDAY AND TUESDAY NIGHT THE POSITION OF THE 850MB CLOSED LOW MOVES
FARTHER EAST...WHICH WOULD FAVOR A PERIOD OF MORE WESTERLY FLOW PER
THE ANALOG COMPARISON CHARTS. THIS SUGGESTION OF BAND MOVEMENT FROM
THE LARGE SCALE FEATURES MATCHES VERY WELL WITH WHAT MOST MESOSCALE
MODEL GUIDANCE IS SUGGESTING.

THE DYNAMIC NATURE OF THE MID LEVEL TROUGH MATCHES WELL WITH LARGE
ANALOG EVENTS FROM THE PAST. IN ADDITION...THE OVERALL PATTERN
APPEARS TO MATCH WELL TO A LAKE EFFECT EVENT FROM EARLY DECEMBER OF
2009 WHICH PRODUCED VERY HEAVY LAKE EFFECT SNOW AND STRONG WINDS
WITH NEAR BLIZZARD CONDITIONS OFF BOTH LAKES. IN FACT...THE CIPS
ANALOG PAGE FROM SAINT LOUIS UNIVERSITY RETURNS THIS DATE AS ONE OF
ITS ANALOGS. EVENTS SIMILAR TO WHAT WE EXPECT FROM THIS EVENT IN THE
PAST HAVE PRODUCED LARGE DISRUPTIONS TO TRAVEL WITH MAJOR HIGHWAY
CLOSURES...INCLUDING THE NYS THRUWAY AND INTERSTATE 81.

LAKE INDUCED INSTABILITY WILL BE EXTREME WITH LAKE INDUCED CAPE
PEAKING AT AROUND 1400J/KG AND EQUILIBRIUM LEVELS AROUND 20K FEET.
SUCH STRONG INSTABILITY AND WELL ALIGNED FLOW IS STRONGLY SUGGESTING
INTENSE SNOWFALL RATES WITH 3-5 INCHES PER HOUR A POSSIBILITY AT
TIMES FROM LATE MONDAY NIGHT THROUGH TUESDAY NIGHT. OUR LAKE EFFECT
LIGHTNING NOMOGRAM FROM LOCAL RESEARCH DONE BY RSH ALSO SUGGESTS A
GOOD POTENTIAL FOR THUNDER AND LIGHTNING OFF BOTH LAKES. WINDS WILL
BE STRONG ESPECIALLY LATE MONDAY NIGHT THROUGH TUESDAY EVENING WITH
GUSTS IN THE 40-45 MPH RANGE RESULTING IN SIGNIFICANT BLOWING AND
DRIFTING SNOW AND NEAR BLIZZARD CONDITIONS AT TIMES IN AND NEAR THE
BANDS.

OFF LAKE ERIE...
EXPECT LAKE EFFECT SNOW TO BEGIN LATE MONDAY AFTERNOON OR EVENING
AND BE FAIRLY WEAK AT FIRST WITH AN INITIAL SYNOPTIC SCALE DRY SLOT
AND DOWNWARD VERTICAL MOTION. LAKE EFFECT SHOULD SLOWLY INCREASE IN
INTENSITY AND CONSOLIDATE INTO A MORE DEFINED BAND AFTER MIDNIGHT AS
MOISTURE AND INSTABILITY INCREASE. EXPECT THE BAND TO INITIALLY BE
BROAD FROM THE BUFFALO SOUTHTOWNS INTO THE NORTHERN PORTIONS OF THE
SOUTHERN TIER. THE BAND SHOULD THEN FOCUS ON SOUTHERN ERIE/WYOMING
COUNTIES AROUND MIDNIGHT...THEN DRIFT NORTH INTO THE BUFFALO
SOUTHTOWNS DURING THE PRE-DAWN HOURS.

ON TUESDAY MORNING EXPECT THE BAND TO DRIFT RIGHT OVER THE HEART OF
THE BUFFALO METRO AREA WITH THE LATEST 12Z MODEL GUIDANCE STILL
TRENDING A LITTLE NORTH OF PREVIOUS RUNS. THE BAND WILL THEN SIT
OVER THE BUFFALO METRO AREA THROUGH AT LEAST EARLY AFTERNOON. THIS
WILL CREATE A LULL FOR THE WESTERN SOUTHERN TIER COUNTIES. BY MID TO
LATE AFTERNOON THE PASSAGE OF A MID LEVEL SHORTWAVE WILL CAUSE
BOUNDARY LAYER FLOW TO VEER...PUSHING THE LAKE BAND BACK SOUTH
THROUGH THE SOUTHTOWNS. TUESDAY NIGHT FLOW WILL BECOME 260-270
BRIEFLY...WHICH WILL PUSH THE BAND BACK INTO THE NORTHERN PORTIONS
OF THE WESTERN SOUTHERN TIER. FINALLY...ON WEDNESDAY BOUNDARY LAYER
FLOW QUICKLY BACKS TO THE SOUTHWEST CARRYING LAKE EFFECT SNOW BACK
NORTH ACROSS THE BUFFALO METRO AREA. BY THIS TIME THE BAND SHOULD BE
IN A WEAKENING PHASE AS INVERSION HEIGHTS BEGIN TO LOWER.

STRONG WINDS...DEEP INSTABILITY...AND AMPLE MOISTURE SHOULD ALLOW
THIS BAND OF SNOW TO TRAVEL WELL INLAND. WITH THIS IN MIND WE HAVE
INCLUDED A LAKE EFFECT SNOW ADVISORY FOR ALLEGANY...LIVINGSTON...AND
MONROE COUNTIES WITH LOCAL 3-6 INCH AMOUNTS MAINLY IN THE WESTERN
PORTIONS OF THOSE COUNTIES.

OFF LAKE ONTARIO...
EXPECT A BROAD AREA OF MAINLY LIGHT SNOW TO DEVELOP MONDAY EVENING
THEN TAKE AWHILE TO CONSOLIDATE INTO A SINGLE BAND. IT SHOULD DO SO
BY TUESDAY MORNING AS SHEAR DECREASES AND INSTABILITY INCREASES. THE
BAND MAY INITIALLY FOCUS ON THE NORTHERN TUG HILL TO JUST SOUTH AND
EAST OF WATERTOWN MONDAY NIGHT...THEN DRIFT NORTH TO WATERTOWN
TUESDAY MORNING AND REMAIN THERE THROUGH MUCH OF THE DAY. THE
PASSAGE OF THE MID LEVEL SHORTWAVE DURING THE LATE AFTERNOON WILL
THEN MOVE THE BAND BACK SOUTH AND FOCUS ON THE CENTRAL TUG HILL
TUESDAY NIGHT AND EARLY WEDNESDAY. THIS SHOULD BE THE TIME PERIOD OF
MOST INTENSE SNOWFALL RATES OFF LAKE ONTARIO. THE BAND WILL MOVE
BACK NORTH BY MIDDAY OR EARLY AFTERNOON THROUGH JEFFERSON COUNTY AND
WEAKEN AS INVERSION HEIGHTS LOWER.

THE LAKE EFFECT SNOW SHOULD TEMPORARILY SHUT DOWN WEDNESDAY
AFTERNOON AS FLOW BECOMES SSW. LATER WEDNESDAY AFTERNOON AND NIGHT A
CLIPPER TROUGH WILL CROSS THE LOWER LAKES. THIS WILL PRODUCE A FEW
SNOW SHOWERS...ESPECIALLY NORTHEAST OF LAKES ERIE AND ONTARIO WITH
SOME LAKE ENHANCEMENT. THIS MAY PRODUCE SOME MINOR ACCUMULATIONS.
BEHIND THE CLIPPER ADDITIONAL LAKE EFFECT SNOW IS LIKELY TO DEVELOP
NORTHEAST OF THE LAKES LATER WEDNESDAY NIGHT ON A SOUTHWEST FLOW...
BUT THE AIRMASS IS NOT QUITE AS COLD AS THE FIRST SO INSTABILITY IS
NOT AS STRONG...AT LEAST INITIALLY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEDNESDAY NIGHT THROUGH FRIDAY ANOTHER SIGNIFICANT LAKE EFFECT EVENT
APPEARS LIKELY AS A FRESH BATCH OF COLD AIR ARRIVES. LAKE INDUCED
INSTABILITY MAY NOT BE QUITE AS STRONG AS THE FIRST EVENT...BUT
STILL SUFFICIENT TO PRODUCE SIGNIFICANT ACCUMULATIONS EAST AND
NORTHEAST OF THE LAKES. THIS SHOULD FINALLY END ON SATURDAY AS HIGH
PRESSURE BUILDS INTO THE OHIO VALLEY AND LOWER LAKES. TEMPERATURES
WILL CONTINUE TO RUN WAY BELOW AVERAGE THROUGH THE END OF THE WEEK.

THE PATTERN WILL CHANGE BY NEXT SUNDAY AND MONDAY AS THE WESTERN
RIDGE BREAKS DOWN AND ALLOWS HEIGHT RISES DOWNSTREAM. BOTH THE GFS
AND ECMWF ARE SUGGESTING A BIG WARM-UP FOR SUNDAY AND MONDAY ALONG
WITH RAIN. IF THIS WERE TO VERIFY...IT WOULD BRING A SIGNIFICANT
FLOODING RISK TO AREAS WHICH RECEIVE HEAVY LAKE EFFECT SNOW THIS
WEEK.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
MAINLY VFR CONDITIONS WILL PREVAIL THROUGH INTO THIS EVENING.
TONIGHT LIGHT SNOW WILL OVERSPREAD THE AREA FROM SOUTHWEST TO
NORTHEAST. FLIGHT CONDITIONS WILL DETERIORATE TO IFR ACROSS MUCH OF
THE REGION.

IFR CONDITIONS WILL CONTINUE TO PREVAIL DURING THE DAY
ON MONDAY BEFORE SOME SLOW IMPROVEMENT MONDAY AFTERNOON AS THE SNOW
DIMINISHES FROM WEST TO EAST. SOME RAIN WILL LIKELY MIX IN WITH THE
SNOW ACROSS CENTRAL NEW YORK...KROC/KART.

OUTLOOK...
TUESDAY...HEAVY LAKE EFFECT SNOW EAST AND NORTHEAST OF THE LAKES
WITH LOCAL VLIFR. MAINLY VFR ELSEWHERE.
WEDNESDAY...LAKE EFFECT SNOW NORTHEAST OF THE LAKES WITH LOCAL
IFR. AREAS OF MVFR ELSEWHERE WITH SCATTERED SNOW SHOWERS.
THURSDAY...HEAVY LAKE EFFECT SNOW EAST AND NORTHEAST OF THE LAKES
WITH LOCAL VLIFR. MAINLY VFR ELSEWHERE.

&&

.MARINE...
WINDS ON LAKE ERIE AND LAKE ONTARIO WILL DIMINISH
OVERNIGHT...ALLOWING THE GENERALLY 2 TO 5 FOOT SEAS TO SUBSIDE THIS
EVENING AND OVERNIGHT. THIS WILL ALLOW FOR A BRIEF BREAK IN THE
SMALL CRAFT ADVISORY CONDITIONS ON MONDAY AS THE WINDS STAY LIGHT
AND TURN TO THE SOUTHEAST.

A COLD FRONT WILL SWEEP ACROSS THE LOWER LAKES MONDAY EVENING. GALE
FORCE WEST TO SOUTHWEST WINDS ARE POSSIBLE TUESDAY MORNING THROUGH
THE EVENING HOURS ON BOTH LAKES. A GALE WATCH REMAINS IN PLACE
FOR THE LAKES WITH THIS PACKAGE. STRONG WINDS WILL THEN CONTINUE
TROUGH THE REST OF THE WEEK WITH PERSISTENT LOW PRESSURE OVER QUEBEC
WITH AT LEAST HIGH END SMALL CRAFT ADVISORIES PROBABLE.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 5 PM EST
     MONDAY FOR NYZ001-002-010>012-019>021-085.
     LAKE EFFECT SNOW WARNING FROM 5 PM MONDAY TO 1 PM EST
     WEDNESDAY FOR NYZ010>012-085.
     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST
     MONDAY FOR NYZ006>008.
     LAKE EFFECT SNOW WARNING FROM 7 PM MONDAY TO 3 PM EST
     WEDNESDAY FOR NYZ006>008.
     LAKE EFFECT SNOW ADVISORY FROM 2 AM TO 7 PM EST TUESDAY FOR
     NYZ003.
     LAKE EFFECT SNOW ADVISORY FROM 5 PM TUESDAY TO 10 AM EST
     WEDNESDAY FOR NYZ021.
     LAKE EFFECT SNOW WARNING FROM 5 PM MONDAY TO 10 AM EST
     WEDNESDAY FOR NYZ019-020.
     LAKE EFFECT SNOW ADVISORY FROM 11 PM MONDAY TO 6 AM EST
     WEDNESDAY FOR NYZ013.
MARINE...GALE WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR
         LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
         LEZ040-041.
         GALE WATCH FROM MONDAY EVENING THROUGH WEDNESDAY
         MORNING FOR LOZ042>045-062>065.
         SMALL CRAFT ADVISORY UNTIL 1 AM EST MONDAY FOR LOZ044-045.

&&

SYNOPSIS...CHURCH/THOMAS
NEAR TERM...CHURCH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...CHURCH
MARINE...CHURCH

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