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Area Forecast Discussion
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000
FXUS61 KBUF 222029
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
329 PM EST MON DEC 22 2014

.SYNOPSIS...
A WEAK LOW PRESSURE SYSTEM WILL MOVE UP THE EAST COAST TONIGHT WHILE 
ANOTHER LOW MOVES INTO THE CENTRAL GREAT LAKES REGION TUESDAY.  BOTH 
WILL HAVE THE POTENTIAL TO BRING SOME LIGHT SHOWERS TO PORTIONS OF 
THE STATE.  THEN...A MUCH STRONGER SYSTEM WILL MOVE UP THE 
MISSISSIPPI VALLEY AND INTO THE CENTRAL GREAT LAKES REGION ON 
WEDNESDAY...WITH ALL OF WESTERN AND CENTRAL NEW YORK SEEING RAIN 
UNDER AN UNSEASONABLY WARM AIRMASS.  A COLD FRONT WILL ARRIVE FOR 
CHRISTMAS DAY WITH STRONG WINDS...FOLLOWED BY SOME MORE RAIN AND 
EVENTUAL SNOW SHOWERS OVER THE REGION BUT WITH LITTLE IF ANY 
ACCUMULATION.

&&

.NEAR TERM /THROUGH TUESDAY/...
A PAIR OF GENERALLY WEAK LOW PRESSURE SYSTEMS WILL ATTEMPT TO BRING 
SHOWERS TO WESTERN AND CENTRAL NEW YORK OVER THE NEXT 24 HOURS.  THE 
FIRST WILL RIDE UP THE EAST COAST OVERNIGHT AND EARLY TUESDAY BEFORE 
FALLING APART...WHILE A SECOND LOW WILL MOVE INTO THE CENTRAL GREAT 
LAKES REGION TUESDAY...BEFORE THIS TOO FALLS APART.  THESE SURFACE 
FEATURES WILL NOT BE ABLE TO FULLY DEVELOP AS THE UPPER LEVEL FLOW 
ACROSS THE US AMPLIFIES...WITH A STRONG RIDGE/TROUGH/RIDGE PATTERN 
FULLY SETTING UP FROM WEST TO EAST ACROSS THE US BY TUESDAY 
AFTERNOON.  THE RESULT WILL BE NEW SURFACE DEVELOPMENT OVER THE GULF 
STATES...THE START OF A LONG AWAITED STORM THAT HAS BEEN BUZZING 
ACROSS THE SOCIAL MEDIA WEATHER WORLD FOR NEARLY A WEEK NOW DUE TO 
ITS HOLIDAY TIMING.

MEANWHILE...TONIGHT...AREAS MAINLY EAST OF THE GENESEE VALLEY WILL 
SEE A POTENTIAL FOR SOME LIGHT RAIN FROM THE DISTANT COASTAL 
LOW...POSSIBLY MIXED IN WITH SOME SLEET OR FREEZING RAIN AT THE 
ONSET DUE TO NEAR FREEZING TEMPERATURES AT THE SURFACE AND WARMER 
AIR ADVECTING IN ALOFT.  THIS AREA OF PRECIPITATION SHOULD MOVE OFF 
TO THE NORTHEAST AND ACROSS THE EASTERN LAKE ONTARIO REGION DURING 
THE MORNING.  

THEN ON TUESDAY...THERE WILL BE AN INCREASING CHANCE OF RAIN...NO 
WINTRY MIX...OVER FAR WESTERN NY DURING THE DAY FROM THE WEAKENING 
GREAT LAKES LOW.  NEITHER SYSTEM IS EXPECTED TO DROP TOO MUCH 
PRECIPITATION...AND WILL KEEP THE AMOUNTS UNDER ABOUT .15 INCH FOR 
THE NEXT 24 HOURS...WITH FAR LESS...IF ANY EXPECTED IN BETWEEN THE 
TWO SYSTEMS.  TEMPERATURES SHOULD STEADILY RISE THROUGHOUT THE 
DAY...IN TO THE 40S BY THE AFTERNOON.  THE WELCOME SUNSHINE ON ONE
OF THE SHORTEST DAYS OF THE YEAR WILL BE A DISTANT MEMORY AS
SEVERAL DAYS OF NEARLY COMPLETE CLOUD COVER BEGINS.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
PERSISTENT LOW/MID LEVEL WARM ADVECTION AND UPPER LEVEL DIVERGENCE 
TUESDAY NIGHT WILL CONTINUE TO PRODUCE A WEALTH OF CLOUD COVER AND 
AT LEAST A FEW SCATTERED SHOWERS. THE INITIAL SERIES OF WEAK LEAD 
MID LEVEL SHORTWAVES WILL LIFT INTO QUEBEC OVERNIGHT WITH ANY 
ORGANIZED SHOWERS FOLLOWING. TOWARD WEDNESDAY MORNING A RENEWED PUSH 
OF STRONGER WARM ADVECTION WILL MOVE INTO THE WESTERN SOUTHERN TIER 
WITH SHOWERS BECOMING MORE WIDESPREAD. IT WILL REMAIN QUITE MILD 
WITH LOWS IN THE LOWER TO MID 40S IN MOST AREAS. THESE LOWS ARE 
LIKELY TO OCCUR EARLY...WITH TEMPERATURES BECOMING EVEN WARMER BY 
WEDNESDAY MORNING.

ON WEDNESDAY A STRONG PUSH OF WARM ADVECTION AND UPPER LEVEL 
DIVERGENCE WILL PRODUCE A PERIODS OF RAIN ACROSS THE ENTIRE REGION. 
THE BROAD AREA OF ASCENT WILL BE ENHANCED BY SEVERAL MID LEVEL 
VORTICITY MAXIMA CROSSING THE REGION DOWNSTREAM OF THE MAIN MID 
LEVEL TROUGH. A PLUME OF DEEP MOISTURE WILL BE CAPTURED AND SPREAD 
NORTHWARD BY THIS SYSTEM WITH PWAT RISING TO AROUND 1.25 
INCHES...WHICH IS OVER 3 STANDARD DEVIATIONS ABOVE AVERAGE AND NEAR 
THE MAX OBSERVED FOR LATE DECEMBER. DESPITE THE COPIOUS AMOUNTS OF 
MOISTURE...IT DOES NOT APPEAR THERE WILL BE ENOUGH OF A FOCUS WITHIN 
THE BROAD WARM ADVECTION REGIME TO PRODUCE EXCESSIVE RAINFALL IN ANY 
ONE LOCATION. MAX RAINFALL AMOUNTS SHOULD FOCUS IN AREAS FAVORED BY 
UPSLOPE SOUTHERLY FLOW...SUCH AS THE SOUTHERN TUG HILL PLATEAU WHERE 
RAIN AMOUNTS MAY EXCEED 1 INCH. ELSEWHERE EXPECT AROUND A HALF INCH 
TOTAL ACROSS LOWER ELEVATIONS AND 3/4 INCH ACROSS THE HIGHER TERRAIN 
OF THE SOUTHERN TIER AND FINGER LAKES. 

WEDNESDAY NIGHT A STRONG COLD FRONT WILL CROSS THE REGION AND 
PRODUCE ONE LAST PERIOD OF RAIN FORCED BY STRONG MID LEVEL HEIGHT 
FALLS AND LOW LEVEL CONVERGENCE ALONG THE FRONTAL ZONE. THE 
SHOWALTER INDEX DROPS TO JUST BELOW ZERO ALONG THE FRONT...SO THERE 
MAY EVEN BE A FEW SCATTERED THUNDERSTORMS. GIVEN THE VERY STRONG 
WIND FIELD ASSOCIATED WITH THE SYSTEM ANY THUNDERSTORM THAT DOES 
FORM MAY PRODUCE GUSTY WINDS. RAIN WILL QUICKLY END FROM WEST TO 
EAST OVERNIGHT WITH THE PASSAGE OF THE SURFACE COLD FRONT...WITH A 
NOTABLE MID LEVEL DRY SLOT CROSSING THE REGION IMMEDIATELY BEHIND 
THE FRONT.

THE MAIN CONCERN WITH THIS SYSTEM CONTINUES TO REVOLVE AROUND WIND 
WITH SOME POTENTIAL FOR DAMAGING WINDS NORTHEAST OF LAKES ERIE AND 
ONTARIO. A SURFACE LOW WILL RAPIDLY DEEPEN AS IT MOVES FROM THE 
LOWER OHIO VALLEY ACROSS MICHIGAN LATE WEDNESDAY BEFORE REACHING 
WESTERN QUEBEC BY CHRISTMAS MORNING. THIS IS A CLIMATOLOGICALLY 
FAVORED TRACK TO PRODUCE STRONG WINDS NORTHEAST OF LAKES ERIE AND 
ONTARIO WHERE WINDS ARE CHANNELLED BY THE LAKES AND TERRAIN. THE 
LATEST GFS CONTINUES TO SUPPORT A MODERATE INTRUSION OF 
STRATOSPHERIC AIR WITH THE DYNAMIC TROPOPAUSE FOLDING DOWN TO AROUND 
500MB...SUGGESTIVE OF DEEPER MID LEVEL INSTABILITY AND MIXING IN THE 
DRY SLOT BEHIND THE COLD FRONT. THE BEST ISALLOBARIC FALL/RISE 
COUPLET IS STILL FORECAST TO PASS THROUGH THE CENTRAL LAKES...BUT 
MODERATE PRESSURE RISES ON THURSDAY WILL STILL AID IN DOWNWARD 
MOMENTUM TRANSFER. 

MODEL GUIDANCE CONTINUES TO SHOW SOME RUN TO RUN VARIANCE WITH 
RESPECT TO THE EXACT TRACK AND STRENGTH OF THE LOW...AND ALSO A GOOD 
DEAL OF RUN TO RUN DIFFERENCES WITH WIND SPEEDS ALOFT. THE LATEST 
12Z GFS TRENDED A LITTLE FASTER AND SLIGHTLY WEAKER WITH THE SURFACE 
LOW AND NOTABLY WEAKER WITH WINDS ALOFT...ALTHOUGH PROBABLY STILL 
JUST STRONG ENOUGH TO PRODUCE 45-50 KNOT GUSTS NORTHEAST OF THE 
LAKES. GIVEN THAT THIS IS STILL ALMOST 3 DAYS AWAY AND WE ARE STILL 
SEEING RUN TO RUN MODEL DIFFERENCES...WILL HOLD OFF ON A HIGH WIND 
WATCH FOR NOW. IT APPEARS THE STRONGEST WINDS WILL OCCUR FROM LATER 
WEDNESDAY NIGHT THROUGH THE FIRST HALF OF CHRISTMAS DAY ACROSS 
WESTERN NY NORTHEAST OF LAKE ERIE...AND A FEW HOURS LATER NORTHEAST 
OF LAKE ONTARIO.

OTHERWISE ON CHRISTMAS DAY A BRIEF PERIOD OF WRAP AROUND MOISTURE 
WILL CROSS THE LOWER LAKES. THERE IS A DISTINCT LACK OF COLD AIR 
BEHIND THIS SYSTEM WITH 850MB TEMPS ONLY DROPPING TO AROUND -6C BY 
THE END OF THE DAY. THIS WILL ONLY SUPPORT A FEW WET SNOWFLAKES 
MIXING IN WITH THE RAIN AT LOWER ELEVATIONS...WITH HIGHER TERRAIN 
PROBABLY CHANGING OVER TO ALL WET SNOW. COULD SEE SOME MINOR LESS 
THAN AN INCH ACCUMULATIONS ON THE HILLS...WITH NO ACCUMULATION 
ACROSS LOWER ELEVATIONS. IT IS NOT EVEN CLOSE TO COLD ENOUGH FOR ANY 
LAKE RESPONSE. TEMPERATURES WILL START OFF IN THE 40S IN MOST AREAS 
AT DAYBREAK THEN FALL INTO THE MID TO UPPER 30S THROUGH THE DAY. IT 
WILL NOT BE A WHITE CHRISTMAS THIS YEAR IN WESTERN NY.

ANY LINGERING LIGHT SNOW SHOWERS EAST OF THE LAKES CHRISTMAS EVENING 
WILL END OVERNIGHT AS A RIDGE OF HIGH PRESSURE BUILDS TOWARDS THE 
LOWER LAKES AND ANY REMAINING MOISTURE IS STRIPPED AWAY.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
ON FRIDAY HIGH PRESSURE WILL BUILD THROUGH THE MID ATLANTIC WITH A 
RIDGE EXTENDING NORTH INTO THE LOWER LAKES AND PROVIDING A DRY DAY 
WITH EVEN A GOOD CHANCE AT SOME SUNSHINE. WHAT LITTLE COOL AIR 
BRIEFLY ENTERS THE REGION ON CHRISTMAS DAY WILL BE GONE AS WARM 
ADVECTION BRINGS 850MB TEMPS TO AROUND +2C. THIS WILL SUPPORT HIGHS 
BACK INTO THE 40S...A GOOD 10 DEGREES ABOVE AVERAGE. ON SATURDAY A 
FAST MOVING MID LEVEL TROUGH WILL SWING THROUGH THE GREAT LAKES AND 
QUEBEC. THIS MAY PRODUCE A FEW RAIN SHOWERS MIXING WITH WET SNOW 
LATER IN THE DAY AS MODERATE COLD ADVECTION BEGINS. IT MAY BECOME 
MARGINALLY COLD ENOUGH FOR SOME LIMITED LAKE EFFECT BY SATURDAY 
NIGHT EAST OF THE LAKES.

MODELS DIVERGE SIGNIFICANTLY BY SUNDAY. THE 12Z ECMWF REMAINS 
CONSISTENT WITH PREVIOUS RUNS IN TAKING A STRONG SOUTHERN STREAM 
TROUGH THROUGH THE OHIO VALLEY AND INTO THE NORTHEAST...WITH A 
FRONTAL WAVE SPREADING A BAND OF ACCUMULATING SNOW ACROSS OUR 
REGION. THE GFS REMAINS CONSISTENT WITH ITS PREVIOUS RUNS IN KEEPING 
ANY SEMBLANCE OF THIS WAVE SUPPRESSED FAR TO THE SOUTHEAST WITH A 
WEAK WAVE RUNNING THROUGH THE SOUTHEAST STATES. THE CANADIAN GEM IS 
CLOSER TO THE ECMWF SOLUTION THROUGH SATURDAY. FOR NOW WILL HEDGE 
TOWARDS THE ECMWF SCENARIO AND PLACE A CHANCE OF SNOW INTO THE 
FORECAST FOR SUNDAY AND SUNDAY NIGHT. BOTH THE GFS AND ECMWF THEN 
SUGGEST A MAINLY DRY MONDAY AS HIGH PRESSURE BUILDS INTO THE 
NORTHEAST.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS ARE EXPECTED THROUGH ABOUT 06Z...THEN EXPECT LOWER
CLOUDS TO MOVE IN FROM THE SOUTH. SOME -SHRA WILL BE AT
POSSIBLE...MAINLY EAST AND SOUTH OF KART AND NORTH AND WEST OF
KIAG. THIS WILL LEAVE MOST OF WESTERN NY GENERALLY DRY THROUGH
18Z TUESDAY WITH MVFR CONDITIONS FROM CIGS. 

OUTLOOK... 
WEDNESDAY...MOSTLY MVFR AND SOME -SHRA.  SOME GUSTY WINDS. 
THURSDAY...MVFR WITH -SHRA/-SHSN AND GUSTY/STRONG WINDS. 
FRIDAY...MAINLY VFR.
SATURDAY...POSSIBLE MVFR CONDITIONS WITH AREAS OF SHSN.

&&

.MARINE...
A WEAK LOW WILL MOVE UP THE EAST COAST TONIGHT AND FALL APART WHILE 
A SECOND LOW MOVES INTO THE CENTRAL GREAT LAKE REGION AND SIMILARLY 
WEAKENS ON TUESDAY.  ON WEDNESDAY...A MUCH STRONGER AND DEEPENING 
SYSTEM WILL MOVE UP THE MS VALLEY AND INTO THE CENTRAL GREAT 
LAKES...WITH SMALL CRAFT AND EVENTUALLY GALE FORE POTENTIAL WINDS 
LATE WEDNESDAY NIGHT AND THURSDAY OVER LAKE ERIE.  GALE FORCE WINDS 
ARE ALSO POSSIBLE ON LAKE ONTARIO LATER THURSDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY 
         AFTERNOON FOR LEZ040-041.

&&

$$

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





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