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Area Forecast Discussion
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000
FXUS61 KBUF 270017
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
717 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/...
EARLY THIS EVENING...A DEEPENING COASTAL LOW IS CENTERED SOUTH OF
CAPE COD AND ADVANCING NORTHWARD UP THE MID ATLANTIC COASTLINE.
RADAR SHOWS LIGHT SNOW MAINLY CONFINED TO AREAS EAST OF ROCHESTER. 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. ADDITIONAL SNOWFALL FROM THE NOR'EASTER
SHOULD BE AN INCH OR TWO EAST OF FULTON...WITH AN INCH OR LESS
WEST OF THIS...AND NIL WEST OF ROCHESTER. STORM TOTALS ARE STILL
EXPECTED TO FALL IN THE ADVISORY RANGE IN LEWIS AND PORTIONS OF
OSWEGO COUNTY.

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. THIS IS CAPTURED BY
SOME HIGH RESOLUTION GUIDANCE INCLUDING THE
RGEM/NAM/HRRR/WRF...WHICH SHOW AN INCREASING LAKE RESPONSE LATE
THIS EVENING AND INTO THURSDAY. LAKE INDUCED CAPE IS
MARGINAL...AND WITH A NORTHERLY FLOW NOT CONDUCIVE TO A SINGULAR
ORGANIZED BAND EXPECT SNOW AMOUNTS TO BE ON THE LIGHT SIDE. THIS
SAID...SHALLOW BANDS OF SNOW MAY BRING A COUPLE OF INCHES OF SNOW
BY MIDDAY THURSDAY. A MINORITY OF GUIDANCE SHOWS A BRIEF
CONVERGENCE BAND DEVELOPING ON LAKE ERIE...WHICH IS FEASIBLE THIS
EVENING INTO THE EARLY MORNING HOURS AS WINDS SHIFT TO THE NORTH.
THIS BAND...IF IT DEVELOPS...IS LIKELY TO IMPACT MAINLY AREAS TO
THE SOUTH AND WEST...BUT IT COULD GLANCE THE LAKE ERIE SHORELINE
IN CHAUTAUQUA COUNTY WITH LOCALIZED SNOWFALL AMOUNTS OF AN INCH OR
SO.

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 WARM UP 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 WARM UP 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 /00Z THURSDAY THROUGH MONDAY/...
AT 00Z LIGHT SNOW HAS ENDED WEST OF ROC...WITH NOTHING MORE THAN
FLURRIES EXPECTED AT BUF/IAG/JHW. DESPITE THIS...EXPECT LINGERING
LAKE MOISTURE TO RESULT IN MVFR CIGS FOR MOST OF THE NIGHT AT
THESE LOCATIONS...WITH LOCALIZED IFR CONDITIONS POSSIBLE AT JHW.

STEADY SNOW SHOULD END AT ROC/ART BY 02Z OR SO...BUT LAKE EFFECT
SNOW SHOWERS SHOULD RE-DEVELOP LATER THIS EVENING. THESE MAY
IMPACT ROC...WITH IFR CIGS ALSO POSSIBLE AS WINDS SHIFT TO THE
NORTH OVERNIGHT. OVERALL...HAVE LOW FORECAST CONFIDENCE IN
ROC GIVEN THE DIFFICULTY IN DE TERMING THE EXACT LOCATION OF LAKE
SNOWS IN A NORTHERLY FLOW. 

ON THURSDAY...EXPECT CIGS TO AVERAGE AROUND 3K FEET...WITH A MIX
OF MVFR/VFR CONDITIONS. PERIODICALLY LOWER CONDITIONS ARE POSSIBLE IN
LAKE EFFECT SNOW SHOWERS AT JHW/ROC.

OUTLOOK...
THURSDAY NIGHT...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. HAVE ISSUED A BRIEF SCA FOR THE SOUTHEASTERN
SHORES OF LAKE ONTARIO BASED ON NE WINDS IN THE 15 TO 20 KT RANGE
WHICH ARE LIKELY TO BUILD WAVES UP TO 5 FEET. THIS WILL BE SHORT
LIVED AS WINDS DIMINISH LATE TONIGHT.

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.

&&

.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...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR LOZ043-044.

&&

$$

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





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