Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 271447
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
947 AM EST THU NOV 27 2014

.SYNOPSIS...
WHILE IT WILL NOT BE QUITE AS COLD AS LAST THANKSGIVING WHEN
TEMPERATURES DID NOT MAKE IT OUT OF THE 20S...TODAY WILL BE ON THE
COLD SIDE OF NORMAL WITH THE MERCURY REACHING CLOSE TO FREEZING. THE
COLD WEATHER WILL PERSIST THROUGH BLACK FRIDAY...ALONG WITH SOME
SNOW SHOWERS THAT WILL ACCUMULATE A FEW INCHES SOUTHEAST OF BOTH
LAKES. IT WILL BECOME NOTICEABLY MILDER DURING THE REMAINDER OF THE
HOLIDAY WEEKEND WHEN THERE WILL BE THE CHANCE FOR SOME SPOTTY LIGHT
RAIN AND WET SNOW SHOWERS.

&&

.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS DISPLAY LAKE ENHANCED SNOW SHOWERS SE OF LAKE
ONTARIO WITH SCATTERED SNOW SHOWERS ELSEWHERE UNDER THE
COLD...CYCLONIC FLOW ALOFT. GREATEST ACCUMULATIONS OF AROUND AN INCH
OR SO THROUGH THE DAYLIGHT HOURS WILL BE SE OF LAKE ONTARIO...AND
ALSO THE HIGHER TERRAIN OF SW NYS WHERE UPSLOPE FLOW COULD INTENSIFY
THESE SNOW SHOWERS SOME.

A SHORTWAVE FOUND OVER THE UPPER GREAT LAKES THIS MORNING WILL PUSH
SOUTHEAST DURING THE DAY AND CROSS OUR FORECAST AREA TONIGHT. THIS
FEATURE WILL GENERATE SCATTERED SNOW SHOWERS ACROSS MUCH OF WESTERN
AND NORTH CENTRAL NEW YORK...WITH DEEPENING COLD AIR AND A RISING
CAP PROMOTING MORE SIGNIFICANT LAKE SNOWS SOUTHEAST OF BOTH LAKES.
AS THE CAP LIFTS TO ARND 15K FT TONIGHT...A NORTHWEST FLOW FEATURING
A FAIR AMOUNT OF SYNOPTIC MOISTURE SHOULD BE ABLE TO SUPPORT
ADVISORY CRITERIA SNOWFALL WITH RATES OF A HALF TO ONE INCH PER
HOUR. THE LAKE SNOW OFF ERIE WILL BE ENHANCED BY THE CHAUTAUQUA
RIDGE...AND SHOULD BE GREATEST LATE THIS AFTERNOON INTO THE WEE
HOURS OF TONIGHT WHEN THE SYNOPTIC MOISTURE WILL BE THE DEEPEST.
WILL THUS GO WITH A LAKE EFFECT SNOW ADVISORY FOR 3-5 INCH ACCUMS
FOR CHAUTAUQUA...CATTARAUGUS...WYOMING (MAINLY SW) AND SRN ERIE
COUNTIES.

WHILE SIMILAR INSTABILITY AND OVERALL THERMAL PROFILE WILL BE
SIMILAR OVER LK ONTARIO...THERE IS A STRONG SUGGESTION FROM THE
SHORT RANGE GUIDANCE THAT AN UPSTREAM CONNECTION WILL BE IN PLACE TO
GEORGIAN BAY. THIS WILL PRIME THE BAND SO THAT SOMEWHAT MORE
EFFICIENT SNOW MAKING WILL BE POSSIBLE. A LAKE SNOW ADVISORY WILL BE
ISSUED FOR SOUTHEAST OF LK ONTARIO AS WELL...WITH ACCUMS OF 3 TO 6
INCHES EXPECTED FROM NRN/ERN WAYNE COUNTY EAST TO OSWEGO COUNTY.

OTHERWISE...SCATTERED SNOW SHOWERS WILL BE FOUND ACROSS OUR REGION
TONIGHT WITH LOW TEMPERATURES RANGING FROM THE UPPER 20S IN THE MORE
PERSISTENT LAKE SNOWS SOUTHEAST OF LK ONTARIO AND ALONG THE LK ERIE
SHORE TO THE LOWER 20S WELL INLAND ACROSS THE SRN TIER AND FOR SITES
GENERALLY NORTH AND EAST OF THE TUG HILL.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
ON FRIDAY...LINGERING TROUGHING ACROSS NEW ENGLAND WILL GRADUALLY
GIVE WAY TO HIGH PRESSURE AND DRIER AIR BUILDING EASTWARD FROM THE
CENTRAL GREAT LAKES. IN BETWEEN THESE TWO SYSTEMS...A NORTHWESTERLY
FLOW OF COLD AIR WILL CONTINUE TO GENERATE SCATTERED TO NUMEROUS
SNOW SHOWERS SOUTHEAST OF THE LAKES DURING THE MORNING...WITH THIS
ACTIVITY THEN SLOWLY LIFTING NORTHWARD AND WEAKENING IN THE
AFTERNOON AS THE STEERING WINDS BACK AND SUBSIDENCE/DRYING
INCREASE.

OFF LAKE ERIE...THE LAKE SNOWS WILL GENERALLY BE MORE SCATTERED AND
LESS ORGANIZED IN NATURE THANKS TO A SHORTER FETCH AND A LOWER CAP
OF AROUND 4 KFT...WHICH SHOULD SERVE TO TO KEEP ANY ADDITIONAL
ACCUMULATIONS CONFINED TO THE ORDER OF AN INCH OR SO. MEANWHILE OFF
LAKE ONTARIO...THE COMBINATION OF A LONGER FETCH...A MUCH HIGHER CAP
OF 8-10 KFT...AND DEEPER MOISTURE SHOULD RESULT IN MORE ORGANIZED/
NUMEROUS SNOW SHOWERS CAPABLE OF PRODUCING A COUPLE MORE INCHES OF
ACCUMULATION DURING THE MORNING...BEFORE THESE DRIFT NORTHWARD AND
WEAKEN DURING THE AFTERNOON. FOR THIS REASON...HAVE MAINTAINED THE
AFOREMENTIONED LAKE EFFECT SNOW ADVISORY FOR THE WAYNE-OSWEGO COUNTY
CORRIDOR THROUGH 18Z FRIDAY.

OUTSIDE OF THE MAIN LAKE EFFECT AREAS...EXPECT PARTLY SUNNY AND
GENERALLY DRY WEATHER DURING THE DAY ON FRIDAY. GIVEN 850 MB TEMPS
AVERAGING AROUND -13C/-14C...HIGH TEMPS WILL BE WELL BELOW AVERAGE
WITH READINGS ONLY PEAKING IN THE MID TO UPPER 20S ACROSS THE HIGHER
TERRAIN...AND IN THE LOWER 30S ACROSS THE LAKE PLAINS.

FRIDAY NIGHT AND SATURDAY...THE AXIS OF THE SURFACE RIDGE WILL SLIDE
EAST AND OFF THE ATLANTIC COASTLINE...WHILE LOW PRESSURE LIFTS FROM
THE NORTHERN PLAINS STATES INTO THE WESTERN GREAT LAKES. IN
CONJUNCTION WITH INCREASING SHEAR...THE RESULTANT WARM AIR ADVECTION
REGIME SHOULD HELP TO SQUELCH ANY LEFTOVER SCATTERED LAKE EFFECT
SNOW SHOWERS AS THESE LIFT TO AREAS NORTHEAST OF THE LAKES FRIDAY
EVENING. AFTER THAT...A MUCH MORE GENERAL CHANCE OF PRECIPITATION
SHOULD THEN FOLLOW FOR THE REMAINDER OF FRIDAY NIGHT...SATURDAY...
AND SATURDAY NIGHT AS A WARM FRONTAL BOUNDARY SLOWLY LIFTS
NORTHEASTWARD ACROSS OUR REGION. AT THIS POINT A CONSENSUS OF THE
00Z GUIDANCE SUGGESTS THAT THE FORCING ALONG THE FRONT WILL BE
RATHER BROAD/WEAK AND ONLY ENOUGH TO PRODUCE SOME SPOTTY LIGHT
QPF...SO HAVE TRENDED POPS FOR THIS TIME FRAME MARKEDLY DOWNWARD TO
THE LOWER HALF OF THE CHANCE RANGE.

GIVEN THE EXPECTED WARM AIR ADVECTION PATTERN...EXPECT FRIDAY
NIGHT`S LOWS TO PREDOMINANTLY OCCUR DURING THE FIRST HALF OF FRIDAY
NIGHT...WITH GENERALLY RISING TEMPS THEN FOLLOWING FROM THE SECOND
HALF OF FRIDAY NIGHT RIGHT ON THROUGH SATURDAY NIGHT. AS A RESULT...
WE SHOULD SEE LOWS MOSTLY IN THE LOWER TO MID 20S FRIDAY NIGHT
GIVING WAY TO HIGHS IN THE MID 30S TO LOWER 40S ON SATURDAY...WITH
READINGS THEN WARMING EVEN FURTHER SATURDAY NIGHT. IN CONJUNCTION
WITH WARMING ALOFT...THIS SHOULD RESULT IN ANY WARM ADVECTIVE
PRECIPITATION BEGINNING IN THE FORM OF SNOW SHOWERS FRIDAY
NIGHT...THEN MIXING WITH AND EVENTUALLY TRANSITIONING TO RAIN
SHOWERS THROUGH THE COURSE OF SATURDAY AND SATURDAY EVENING.

ON SUNDAY...EXPECT THE WARMEST CONDITIONS OF THE WEEKEND WITH OUR
REGION SITUATED SQUARELY WITHIN THE WARM SECTOR OF LOW PRESSURE
LIFTING FROM THE CENTRAL GREAT LAKES TO WESTERN QUEBEC. UNDER A DEEP
SOUTHWESTERLY FLOW...925 MB TEMPS WILL CLIMB TO AROUND +4C EAST AND
AROUND +9C WEST...WHICH SHOULD TRANSLATE INTO HIGHS REACHING THE
LOWER TO MID 50S...WITH THE EXCEPTION OF INTERIOR PORTIONS OF THE
NORTH COUNTRY WHICH SHOULD REMAIN CONFINED TO THE MID AND UPPER 40S.
OTHERWISE...WITH ANY FORCING WITHIN THE WARM SECTOR REMAINING RATHER
WEAK AND DIFFUSE IN NATURE...EXPECT FAIRLY CLOUDY SKIES TO PREVAIL
WITH JUST A LOWER-END CHANCE OF A FEW SHOWERS...WITH MOST LOCATIONS
MORE LIKELY TO REMAIN DRY.

THIS PERIOD WILL THEN END WITH THE WARMER TEMPERATURES COMING TO AN
END SUNDAY NIGHT AS THE AFOREMENTIONED LOW SWEEPS ITS TRAILING
COLD FRONT INTO OUR REGION. THIS FRONT MAY BRING ANOTHER ROUND OF
RAIN SHOWERS TO THE REGION...WHICH COULD MIX WITH A LITTLE LIGHT
SNOW LATE AS TEMPS COOL OFF.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
ON MONDAY...A MIX OF RAIN AND SNOW SHOWERS ASSOCIATED WITH THE COLD
FRONT WILL GRADUALLY WIND DOWN THROUGH THE DAY AS THIS FEATURE
DEPARTS TO OUR SOUTH AND EAST. IN ITS WAKE...A FRESH NORTHWESTERLY
FLOW OF MUCH COLDER AIR MAY HELP TO GENERATE SOME LIMITED LAKE
EFFECT SNOW SHOWERS SOUTHEAST OF THE LAKES MONDAY NIGHT...HOWEVER
THESE SHOULD QUICKLY END ALTOGETHER BY TUESDAY MORNING AS STRONG
SURFACE BASED RIDGING AND ATTENDANT DRYING/SUBSIDENCE BUILDS ACROSS
THE LOWER GREAT LAKES. THIS LATTER FEATURE WILL BRING FAIR AND DRY
WEATHER ON TUESDAY...BEFORE ANOTHER FRONTAL SYSTEM BRINGS A RENEWED
CHANCE FOR RAIN AND SNOW SHOWERS TUESDAY NIGHT AND WEDNESDAY.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
A COLD CYCLONIC FLOW OVER THE LOWER GREAT LAKES WILL GENERATE SOME
AREAS OF LIGHT SNOW AND FLURRIES TODAY...ALTHOUGH VFR CONDITIONS
SHOULD PREVAIL. THE EXCEPTION WILL BE ACROSS THE SRN TIER WHERE MVFR
CIGS ARE EXPECTED AFTER MID MORNING.

BY MID AND LATE AFTERNOON...THE NEXT DISTURBANCE WILL BE NEARING OUR
REGION WITH LOWERING CIGS AND AREAS OF STEADIER LIGHT SNOW REDUCING
CONDITIONS TO MVFR OVER THE FAR WESTERN COUNTIES. THIS NUISANCE
ACTIVITY IS NOT EXPECTED TO IMPACT FIELD OPERATIONS THOUGH...WITH NO
LOCALLY DERIVED WEATHER DELAYS ANTICIPATED.

MVFR TO IFR CONDITIONS CAN THEN BE EXPECTED TONIGHT...WITH FAIRLY
WIDESPREAD LAKE SNOWS ACROSS THE SRN TIER AND ALSO SOUTHEAST OF LAKE
ONTARIO. IN THESE AREAS...IFR TO LIFR CONDITIONS ARE EXPECTED.

OUTLOOK...
FRIDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS/MVFR.
SATURDAY THROUGH MONDAY...MAINLY VFR WITH A CHANCE OF RAIN AND SNOW
SHOWERS.

&&

.MARINE...
A WEAK SFC TROUGH WILL BE FOUND OVER THE LOWER GREAT LAKES TODAY
WHILE A NOR`EASTER WILL EXITING ACROSS THE CANADIAN MARITIMES. THIS
WILL ALLOW THE SFC PRESSURE TO WEAKEN ACROSS LAKES ERIE AND ONTARIO
SO THAT WINDS AND WAVES WILL BE UNDER SMALL CRAFT ADVISORY CRITERIA.

AN UPPER LEVEL DISTURBANCE WILL PASS OVER THE LOWER GREAT LAKES
TONIGHT. A MODERATELY STRONG LOW LEVEL JET ASSOCIATED WITH THIS
FEATURE WILL COMBINE WITH SOME COLD ADVECTION TO FRESHEN THE WINDS
ON BOTH LAKES...WITH WINDS AND WAVES POSSIBLY REACHING SCA CRITERIA.

WHILE SFC HIGH PRESSURE WILL NOSE ACROSS THE LOWER GREAT LAKES FROM
THE OHIO VALLEY ON FRIDAY...WINDS WILL FRESHEN ON LAKE ONTARIO WITH
WAVES LIKELY REACHING 5 FEET ON THE NEARSHORE WATERS. AGAIN...A SCA
FOR THIS PERIOD CAN BE ISSUED IN A LATER FORECAST PACKAGE.

&&

.CLIMATE...
AFTER AN EXTENDED PERIOD OF COLD DURING THE MIDDLE OF NOVEMBER IT
APPEARS TEMPERATURES WILL AVERAGE ABOVE NORMAL MOST OF THE TIME OVER
THE NEXT FEW WEEKS. THERE WILL BE BRIEF PUSHES OF COLDER AIR AT
TIMES AS PROGRESSIVE TROUGHS AMPLIFY INTO THE GREAT LAKES...BUT
THESE COLD PERIODS WILL BE SHORT LIVED...ONLY LASTING FOR A FEW DAYS
AT A TIME...AND WILL BE OUTNUMBERED BY MILD DAYS.

LOOKING AT THE HEMISPHERIC PATTERN...A POSITIVE NORTH ATLANTIC
OSCILLATION /NAO/ WILL PERSIST INTO THE FIRST FEW DAYS OF DECEMBER
BASED ON THE GEFS ENSEMBLE MEAN. THE MEAN LONGWAVE TROUGH OVER THE
NORTH ATLANTIC IN SUCH A PATTERN WILL PREVENT ANY COLD FROM LOCKING
IN OVER THE NORTHEAST QUARTER OF THE UNITED STATES. THE PACIFIC
NORTH AMERICAN PATTERN /PNA/ WILL REMAIN NEGATIVE THROUGH THE FIRST
FEW DAYS OF DECEMBER...BEFORE TRENDING POSITIVE BASED ON GEFS
ENSEMBLE MEMBERS. THIS TOO WILL PREVENT COLD FROM LOCKING INTO THE
NORTHEAST FOR MORE THAN A FEW DAYS AT A TIME.

THE MADDEN JULIAN OSCILLATION /MJO/ MAY PLAY AN IMPORTANT ROLE IN
DRIVING PATTERN CHANGE THROUGH MID DECEMBER. ANALYSIS OVER THE PAST
WEEK HAS SHOWN A MODERATELY STRONG MJO EVENT DEVELOPING OVER THE
INDIAN OCEAN. A GEFS ENSEMBLE FORECAST OF THE WHEELER PHASE/SPACE
PLOT SHOWS THIS MJO ORBITING THROUGH PHASE 4 AND 5 DURING THE FIRST
WEEK IN DECEMBER AS CONVECTION MOVES EAST ACROSS THE MARITIME
CONTINENT. A LOOK AT COMPOSITE CHARTS OF PAST EVENTS FAVORS ABOVE
NORMAL TEMPERATURES ACROSS MUCH OF THE CENTRAL AND EASTERN UNITED
STATES DURING PHASE 4 THROUGH 6 OF THE MJO.

EVENTUALLY AS WE GET INTO THE SECOND WEEK IN DECEMBER MJO CONVECTION
WILL CONTINUE ITS EASTWARD ORBIT THROUGH THE PACIFIC AND INTO THE
WESTERN HEMISPHERE. IF THE MJO CONVECTION PERSISTS ON ITS EASTWARD
JOURNEY AND REACHES PHASE 7 OF THE WHEELER PHASE/SPACE PLOT...IT
WOULD FAVOR A SIGNIFICANT PATTERN CHANGE TOWARDS COLDER THAN NORMAL
TEMPERATURES OVER THE CENTRAL AND EASTERN UNITED STATES. THE MJO
ACCOMPLISHES THIS AS SUB-TROPICAL CONVECTION INFLUENCES THE PATTERN
OVER THE PACIFIC...FORCING AMPLIFICATION OF THE EASTWARD EXTENSION
OF THE EAST ASIAN JET WHICH IN TURN FORCES DOWNSTREAM AMPLIFICATION
OF THE PATTERN ACROSS NORTH AMERICA. BASED ON THE FORECAST TIMING OF
THE MJO EPISODE THIS WOULD MOST LIKELY OCCUR BY WEEK 2 OR 3 OF
DECEMBER AND FEED BACK INTO MORE HIGH LATITUDE BLOCKING AND MORE
LONG LASTING COLD.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST
     FRIDAY FOR NYZ004>006.
     LAKE EFFECT SNOW ADVISORY FROM 4 PM THIS AFTERNOON TO 5 AM EST
     FRIDAY FOR NYZ012-019-020-085.
MARINE...NONE.

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH/THOMAS
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH
CLIMATE...HITCHCOCK






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