Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 262034
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
334 PM EST WED NOV 26 2014

.SYNOPSIS...
A NOR`EASTER WILL LIFT ALONG THE ATLANTIC COASTLINE THROUGH TONIGHT
AND BRING LIGHT SNOW ACROSS OUR REGION THROUGH THE EVENING HOURS. SNOW
ACCUMULATIONS WILL RANGE FROM A FRESH COATING ACROSS WESTERN AREAS
TO SEVERAL INCHES ACROSS THE SOUTHERN GENESEE AND FINGER LAKES
REGION. THIS SNOW WILL TAPER OFF THIS EVENING FROM WEST TO
EAST...THOUGH SOME LIMITED LAKE ENHANCED ACTIVITY WILL LINGERING
INTO THANKSGIVING MORNING...ESPECIALLY SOUTHEAST OF LAKE ONTARIO.

&&

.NEAR TERM /THROUGH THURSDAY/...
THIS AFTERNOON A DEEPENING COASTAL LOW IS ADVANCING NORTHWARD UP THE
MID ATLANTIC COASTLINE. WATER VAPOR IMAGERY DISPLAYS A BAROCLINIC
LEAF SIGNATURE GENERALLY EAST OF I-81 AND ACROSS NEW ENGLAND THIS
AFTERNOON...CORRESPONDING TO AN AREA OF GREATEST LIFT.

THROUGH THIS TIME PERIOD THERE WILL BE TWO IMPACTS...FIRST FROM THE
ONGOING NOR`EASTER...AND THEN SOME LIMITED AND LOCALIZED LAKE EFFECT
SNOW ACTIVITY.

FOR THE NOR`EASTER...THIS COASTAL LOW WILL CONTINUE ITS
NORTHEASTWARD TRACK TONIGHT REACHING ATLANTIC CANADA BY THURSDAY
MORNING. THE WESTERN SHIELD OF SNOW ACROSS WESTERN NEW YORK WILL
ADVANCE EASTWARD TONIGHT WITH SYNOPTIC SNOW ENDING FROM WEST TO EAST
THROUGH THE EVENING HOURS. AREAS WHERE SNOW LINGERS LONGEST AND
TOWARDS GREATER LIFT...ACROSS OSWEGO AND LEWIS COUNTIES SNOWFALL
TOTALS MAY LOCALLY REACH HALF A FOOT...FOR SUCH A WINTER WEATHER
ADVISORY WILL BE IN PLACE. OTHERWISE JUST A FEW INCHES OF SNOW
FROM THE SOUTHERN GENESEE VALLEY AND INTO THE FINGER LAKES
REGION...AND DOWN TO A COATING OF FRESH SNOW FARTHER WESTWARD
TOWARDS LAKE ERIE.

BY LATE TONIGHT THE SYNOPTIC SNOW WILL BE TAPERING OFF ACROSS OUR
EASTERN ZONES...HOWEVER A COLD -10C 850 HPA AIRMASS WILL BE PULLED
SOUTHWARD ACROSS BOTH GREAT LAKES LATE TONIGHT AND TOMORROW. A
NORTH-NORTHWESTERLY WIND THAT WILL BE ALIGNED IN THE SHALLOW 4K
CAPPING INVERSION WILL LIKELY BRING LAKE EFFECT SNOW SHOWERS INLAND
ACROSS WAYNE-CAYUGA AND WESTERN OSWEGO COUNTY. THOUGH SHALLOW BANDS
OF SNOW...PERSISTENT BANDS MAY END UP BRING A COUPLE OF INCHES OF
SNOW BY MIDDAY THURSDAY. THESE NORTHWESTERLY WINDS MAY ALSO BRING
LIGHT SNOW SHOWERS ACROSS THE WESTERN SOUTHERN TIER LATE TONIGHT
AND TOMORROW...BUT THE SHORT FETCH OVER LAKE ERIE...AND LESS LOW
LEVEL CONVERGENCE SHOULD LIMIT SNOW ACCUMULATIONS TO LESS THAN AN
INCH.

AN UPPER LEVEL SHORTWAVE CROSSING FROM THE CENTRAL GREAT LAKES TO
THE EASTERN GREAT LAKES THROUGH THE DAY TOMORROW MAY BRING LIGHT
SNOW AGAIN INTO WESTERN NEW YORK BY THE END OF THE AFTERNOON.

TEMPERATURES WILL AVERAGE A SEVERAL DEGREES BELOW NORMAL THIS PERIOD.
LOWS TONIGHT WILL RANGE THROUGH THE 20S AND HIGHS TOMORROW WILL
RANGE THROUGH THE LOW TO MID 30S.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THE LATEST SURGE OF ARCTIC AIR WILL BRING A RENEWED THREAT FOR
ACCUMULATING LAKE EFFECT SNOWS THURSDAY NIGHT AND INTO FRIDAY TO
FAVORED NORTHWEST FLOW AREAS...ESPECIALLY OFF LAKE ERIE WHERE A
BETTER ALIGNED LOW LEVEL FLOW WILL EXIST.

ALTHOUGH OVER-LAKE INSTABILITY WILL NOT BE OVERLY IMPRESSIVE WITH
DELTA T/S AROUND 15C...LAKE INDUCED EQUILIBRIUM LEVELS LOOK TO RISE
TO OVER 10K FEET FOR A TIME THURSDAY NIGHT. THIS MAY ALLOW FOR
LOCALIZED ACCUMULATIONS OF 2-4" ALONG THE CHAUTAUQUA RIDGE.

FRIDAY...COLD AIR ADVECTION WILL CONTINUE ON A NORTHWEST FLOW WHICH
SHOULD MAINTAIN SOME MULTIPLE LAKE BANDS SOUTHEAST OF THE LAKES
EARLY IN THE DAY. THESE BANDS SHOULD WANE THROUGH THE DAY AS THE LOW
LEVEL FLOW BACKS AND INFLUX OF DRY AIR AND LOWER INVERSION HEIGHTS
HELP TO DIMINISH THE LAKE ACTIVITY.

FRIDAY NIGHT AND SATURDAY...STRONG WARM ADVECTION AND ISENTROPIC
ASCENT DEVELOPS AS A CLIPPER SYSTEM WORKS ACROSS THE REGION. MODELS
SUGGESTING A SHARP INCREASE IN LOW LEVEL MOISTURE SIGNALING
WIDESPREAD SNOW WILL DEVELOP ACROSS THE REGION DURING THIS PERIOD.
THE STRENGTHENING OF THE WARM AIR ADVECTION AND MOISTURE SURGE
SHOULD BE ABLE TO PRODUCE AT LEAST A COUPLE INCHES OF ACCUMULATING
SNOW. HOW MUCH SNOW FALLS WILL BE DEPENDENT ON THE AMOUNT OF
MOISTURE AND WARM AIR BEING BROUGHT INTO THE REGION...BUT AT THIS
TIME THERE IS NO REASON TO BELIEVE THERE WILL BE ANYTHING MORE THAN
MINOR ACCUMULATIONS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SOLID WARMUP STILL LOOKS ON TRACK FOR SUNDAY IN WAKE OF A WARM
FRONTAL PASSAGE. 925 MB TEMPERATURES LOOK TO RISE TO NEAR
+10C...WHICH SHOULD SUPPORT HIGHS FOR MOST AREAS IN THE LOWER TO MID
50S. DOES NOT APPEAR TO BE ANY REAL FORCING MECHANISM FOR
PRECIPITATION WITHIN THE WARM SECTOR OTHER THAN WEAK ISENTROPIC LIFT
WITH BROAD WARM AIR ADVECTION. THIS WARMUP APPEARS SHORT-LIVED AS A
ROUND OF UPPER MIDWEST TO GREAT LAKES HEIGHT FALLS WILL FORCE A COLD
FRONT SOUTH ACROSS THE AREA LATE SUNDAY NIGHT INTO MONDAY. BAND OF
SHOWERS PRECEDING THE FRONT LIKELY HOLDING OFF UNTIL SUNDAY
NIGHT...POSSIBLY ENDING AS A BIT OF LIGHT SNOW AS COLDER AIR SPREADS
INTO THE REGION BEHIND THE FRONT. ANY LAKE EFFECT WHICH CAN
MATERIALIZE MONDAY SHOULD END BY MONDAY NIGHT AS SUBSIDENCE AND
SURFACE RIDGING MOVE INTO WESTERN NEW YORK. HIGH PRESSURE WILL
PROVIDE A FAIR WEATHER DAY TUESDAY...BEFORE WARM AIR ADVECTION
PRECIPITATION BREAKS OUT AS STRENGTHENING RETURN FLOW SETS UP BEHIND
THE DEPARTING HIGH.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
AT 18Z LIGHT SNOW HAS REACHED THE SOUTHERN TIER AND FINGER LAKES
REGION FROM THE COASTAL LOW. THIS SNOW IS BRINGING VISIBILITIES DOWN
TO IFR RANGE...WITH MVFR VSBYS FOUND ON THE OUTER PERIPHERY OF THE
SNOW. FOR THE AIRFIELDS EXPECT A REDUCTION TO MVFR...AND POSSIBLY
SOME IFR WHERE THE SNOW INTENSITY WILL BE BRIEFLY HIGHER.

THIS SYSTEM WILL PULL AWAY FROM OUR REGION TONIGHT WITH LIGHT WINDS
BACKING AROUND TO NORTHWESTERLY. EXPECT VFR/MVFR FLIGHT CONDITIONS
FOR THE REMAINING 12 HOURS OR SO OF THE TAF PERIOD WITH GENERAL DRY
CONDITIONS FOR THE AIRFIELDS.

OUTLOOK...
THURSDAY...SNOW SHOWERS AND IFR/MVFR BECOMING LIKELY ACROSS FAR
SOUTHWESTERN NEW YORK...OTHERWISE MAINLY VFR WITH A CHANCE OF MVFR
IN SNOW SHOWERS.
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 DEVELOPING STORM SYSTEM WILL LIFT NORTHEASTWARD ALONG THE ATLANTIC
COASTLINE TONIGHT. NORTHERLY WINDS THAT WILL BACK TO NORTHWESTERLY
MAY INCREASE TO AROUND 15 KNOTS ON THE SOUTHERN SHORELINE OF LAKE
ONTARIO...BUT WAVES SHOULD REMAIN JUST BELOW 4 FEET AND THUS WILL
DROP THE SCA FOR PORTIONS OF LAKE ONTARIO.

IN THE WAKE OF THIS SYSTEM...A SECONDARY SURFACE TROUGH WILL THEN
CROSS THE LOWER LAKES REGION LATER THURSDAY AND THURSDAY NIGHT...AND
WILL LIKELY BE ACCOMPANIED BY A PERIOD OF ADVISORY-LEVEL WESTERLIES
AND ATTENDANT HIGHER WAVES.

&&

.HYDROLOGY...
THE FLOODING THREAT FOR WESTERN NEW YORK HAS LARGELY ENDED AS
TEMPERATURES HAVE DROPPED BELOW FREEZING...WHICH ENDED THE
SNOW MELT RUN OFF. IT IS WORTH NOTING THAT SOME OF THE SLOWER
RESPONDING CREEKS ACROSS THE AREA...NAMELY TONAWANDA CREEK IN
NORTHERN ERIE COUNTRY WILL CONTINUE TO RISE OVER THE NEXT 12
HOURS...BUT SHOULD REMAIN BELOW FLOOD STAGE.

&&

.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...WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ006-008.
MARINE...NONE.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...THOMAS
MARINE...JJR/THOMAS
HYDROLOGY...WOOD/THOMAS
CLIMATE...HITCHCOCK






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