Area Forecast Discussion
Issued by NWS Buffalo, NY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
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





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.