Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 250516
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1216 AM EST THU DEC 25 2014

.SYNOPSIS...
LOW PRESSURE NEAR GEORGIAN BAY WILL RAPIDLY DEEPEN OVERNIGHT AND
CHRISTMAS DAY AS IT WILL LIFT TO WESTERN QUEBEC. THIS LOW WILL SWEEP
ITS TRAILING COLD FRONT ACROSS THE REGION IN THE PROCESS...WITH A
RETURN TO COLDER WEATHER AND A PERIOD OF STRONG WINDS IN ITS WAKE
THROUGH CHRISTMAS DAY. WHILE THE LOWER TEMPERATURES WILL ALLOW ANY
LEFTOVER RAIN SHOWERS TO MIX WITH SOME SNOW CHRISTMAS DAY...THERE
WILL BE LITTLE TO NO ACCUMULATION.

&&

.NEAR TERM /THROUGH TODAY/...
...STRONG TO POTENTIALLY DAMAGING WINDS OVERNIGHT INTO CHRISTMAS...
THIS PERIOD WILL FEATURE VERY ACTIVE WEATHER AS LOW PRESSURE NEAR
GEORGIAN BAY WILL EXPLOSIVELY DEEPEN AS IT WILL TRACK NORTHEAST TO
WESTERN QUEBEC FOR CHRISTMAS DAY. AS THIS FEATURE BOMBS OUT...IT
WILL SWEEP ITS TRAILING COLD FRONT ACROSS WESTERN AND NORTH CENTRAL
NEW YORK.

IMMEDIATELY IN THE WAKE OF THE FRONT...WINDS WILL TURN SOUTHWESTERLY
AND SHOULD SHARPLY INCREASE AS COLD AIR ADVECTION DEVELOPS...AND
HELPS TO MIX HIGHER MOMENTUM AIR FROM ALOFT DOWN TO THE SURFACE...
WITH THIS PROCESS BEING FURTHER AIDED NORTHEAST OF THE LAKES BY THE
USUAL FUNNELING EFFECTS. GIVEN THAT ANYWHERE FROM 45-60 KNOTS OF
WIND WILL BE AVAILABLE ONLY 1-2 KFT OFF THE DECK...FEEL THAT OUR
CURRENT WIND HEADLINES ARE IN EXCELLENT SHAPE WITH WARNING-CRITERIA
WIND GUSTS STILL APPEARING HIGHLY LIKELY NORTHEAST OF THE LAKES...
AND SOLID ADVISORY-TYPE GUSTS EQUALLY LIKELY ELSEWHERE. THE
STRONGEST OVERALL WINDS WILL BE MOST LIKELY TO OCCUR FROM THE TIME
OF FROPA RIGHT ON THROUGH EARLY CHRISTMAS MORNING...WHEN BOTH THE
WINDS ALOFT AND LOW LEVEL COLD AIR ADVECTION REGIME WILL BE AT THEIR
STRONGEST. AFTER THAT TIME...THE WINDS SHOULD GRADUALLY DIMINISH
THROUGH THE REST OF CHRISTMAS DAY AS WINDS ALOFT WEAKEN AND THE
PRESSURE GRADIENT BEGINS TO RELAX.

ONE OTHER NOTABLE CONSEQUENCE OF THE STRONG WINDS WILL BE THE
LIKELIHOOD OF A SEICHE AND SUBSEQUENT LAKESHORE FLOODING AT THE
NORTHEAST ENDS OF BOTH LAKES ERIE AND ONTARIO...FOR WHICH LAKESHORE
FLOOD WARNINGS HAVE ALSO BEEN HOISTED. FOR MORE DETAILS ON
THESE...PLEASE REFER TO THE COASTAL FLOODING SECTION BELOW.

IMMEDIATELY FOLLOWING THE FROPA...SHARP DRY SLOTTING AND SUBSIDENCE
SHOULD LEAD TO A BREAK IN THE PRECIPITATION...BEFORE INCREASING
WRAPAROUND MOISTURE AND OROGRAPHIC INFLUENCES LEADS TO THE
DEVELOPMENT OF SCATTERED TO NUMEROUS RAIN AND SNOW SHOWERS DOWNWIND
OF THE LAKES FOR A TIME LATER TONIGHT AND CHRISTMAS MORNING. AT THIS
POINT...AVAILABLE MOISTURE STILL APPEARS SUFFICIENT ENOUGH TO
WARRANT AN ASSOCIATED MIX OF CHANCE AND LIKELY POPS...WITH THE
GREATEST PRECIP CHANCES FOCUSING ACROSS THE HIGHER TERRAIN EAST OF
BOTH LAKES. PTYPE WITH THESE WILL START OFF AS PREDOMINANTLY RAIN
BEFORE GRADUALLY MIXING WITH SOME WET SNOW ACROSS THE HIGHER TERRAIN
AS THE ATMOSPHERE SLOWLY COOLS...THOUGH WITH VERY MARGINAL BOUNDARY
LAYER TEMPS AND TEMPERATURE PROFILES IN PLACE...EXPECT THERE TO BE
LITTLE...IF ANY ACCUMULATION AT ALL. ALL OF THIS SHOULD THEN TEND TO
FADE FROM WEST TO EAST DURING THE AFTERNOON AS THE DEEPER WRAPAROUND
MOISTURE GETS STRIPPED AWAY...LEAVING BEHIND LITTLE MORE THAN SOME
STRAY LEFTOVER ACTIVITY ACROSS THE TUG HILL/WESTERN ADIRONDACK
FOOTHILLS BY TOMORROW EVENING. OUTSIDE OF THE ABOVE AREAS OF
PRECIP...EXPECT GENERALLY DRY CONDITIONS...ALONG WITH SOME BREAKS OF
SUNSHINE MIXING IN DURING THE AFTERNOON.

WITH RESPECT TO TEMPS...AFTER TODAY/S UNSEASONABLY MILD CONDITIONS
EXPECT READINGS TO FALL BACK TO THE MID 30S TO LOWER 40S IN THE WAKE
OF TONIGHT`S FROPA...WITH PERSISTENT COLD AIR ADVECTION THEN
RESULTING IN TEMPS EITHER FLATLINING OR EVEN DROPPING A LITTLE
FURTHER DURING THE COURSE OF CHRISTMAS DAY.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
THURSDAY EVENING ANY REMAINING LIGHT UPSLOPE RAIN/SNOW SHOWERS EAST
OF THE LAKES WILL COME TO AN END AS DEEPER MOISTURE IS STRIPPED
AWAY. THE AIRMASS IS NOT COLD ENOUGH TO SUPPORT ANY LAKE RESPONSE
OTHER THAN SOME ADDED CLOUD COVER...SO EXPECT PRECIP TO QUICKLY END
DURING THE EARLY EVENING. WARM ADVECTION WILL BEGIN OVERNIGHT AND
THIS MAY PRODUCE SOME MID LEVEL CLOUD COVER...ESPECIALLY OVER AND
NORTHEAST OF LAKE ONTARIO. LOWS WILL STILL BE VERY MILD FOR THIS
TIME OF YEAR WITH LOW TO MID 30S ON THE LAKE PLAINS AND UPPER 20S
ACROSS INTERIOR VALLEYS.

ON FRIDAY HIGH PRESSURE WILL REMAIN IN PLACE OVER THE MID ATLANTIC
STATES. THE SOUTHWESTERLY FLOW AROUND THE PERIPHERY OF THIS HIGH
WILL BOOST 850MB TEMPS TO AROUND +2C...WHICH WILL SUPPORT HIGHS IN
THE MID 40S AT LOWER ELEVATIONS AND LOWER 40S ACROSS HIGHER TERRAIN.
THE NORMALLY WARMER LOCATIONS IN THE GENESEE VALLEY MAY REACH THE
UPPER 40S. ONGOING WARM ADVECTION IN THE MID LEVELS MAY PRODUCE SOME
PERIODS OF MID LEVEL CLOUDS...BUT STILL EXPECT AT LEAST PARTIAL
SUNSHINE.

EXPECT MORE OF THE SAME FRIDAY NIGHT AND SATURDAY WITH ONGOING WEAK
WARM ADVECTION IN SOUTHWESTERLY FLOW PRODUCING SOME CLOUD COVER AND
MILD TEMPERATURES. HIGHS ON SATURDAY WILL AGAIN BE IN THE 40S WITH
850MB TEMPS ABOVE 0C. LATEST 12Z MODEL GUIDANCE CONTINUES WITH A
SLOWER TREND IN THE APPROACH OF THE NEXT SYSTEM...SO THERE IS ENOUGH
CONFIDENCE NOW TO REMOVE ANY POPS FROM SATURDAY.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SATURDAY NIGHT A FAST MOVING MID LEVEL SHORTWAVE AND SURFACE COLD
FRONT WILL CROSS THE LOWER LAKES REGION. A PERIOD OF LARGE SCALE
ASCENT IN THE DPVA AND UPPER LEVEL DIVERGENCE REGIME AHEAD OF THE
TROUGH WILL SUPPORT A GOOD CHANCE OF PRECIP. THE BOUNDARY LAYER IS
MORE THAN WARM ENOUGH FOR ALL RAIN THROUGH MOST OF THIS...PERHAPS
ENDING AS SOME WET SNOW BRIEFLY SUNDAY MORNING.

SUNDAY INTO EARLY NEXT WEEK MODEL GUIDANCE HAS STRUGGLED MIGHTILY
OVER THE PAST FEW DAYS WITH THE HANDLING OF SYNOPTIC SCALE FEATURES
AND EVEN THE LONGWAVE PATTERN. THE ECMWF HAS BEEN THE MOST
INCONSISTENT WITH LARGE RUN TO RUN SWINGS IN INDIVIDUAL SYSTEMS. THE
LATEST 12Z RUN HAS TRENDED STRONGLY TOWARDS THE GFS FOR SUNDAY
THROUGH TUESDAY IN KEEPING SOUTHERN STREAM ENERGY SUPPRESSED INTO
THE MID ATLANTIC WHILE HIGH PRESSURE DOMINATES THE GREAT LAKES. A
LOOK THROUGH ALL OF THE 12Z GEFS ENSEMBLE MEMBERS STILL SHOWS A
NOTEWORTHY NUMBER DEVELOPING MORE OF A FRONTAL WAVE ACROSS THE MID
ATLANTIC SUNDAY NIGHT AND MONDAY THAN THE OPERATIONAL GFS OR ECMWF.
THE 00Z ECMWF ENSEMBLE MEAN ALSO SUPPORTED SOMETHING ALONG THESE
LINES...ALBEIT A FULL DAY AND A HALF LATER.

THIS PATTERN IS PARTICULARLY DIFFICULT FOR MODEL GUIDANCE TO
FORECAST...WITH A BROAD NORTHERN TROUGH CENTERED ON THE NORTHERN
PLAINS COUPLED WITH AN ACTIVE SOUTHERN STREAM. ODDS FAVOR THE DRY
OPERATIONAL GFS AND ECMWF SOLUTIONS FROM LATER SUNDAY THROUGH
TUESDAY BUT GIVEN THE LOOK OF SOME ENSEMBLE GUIDANCE WILL HOLD ONTO
LOW CHANCE POPS SUNDAY NIGHT AND MONDAY FOR ONE MORE DAY BEFORE
GOING WITH A COMPLETELY DRY FORECAST. TEMPERATURES WILL RETURN TO
VERY NEAR SEASONAL NORMALS FOR THE FIRST HALF OF NEXT WEEK WITH ANY
POTENTIAL BELOW NORMAL TEMPERATURES PROBABLY DELAYED UNTIL AT LEAST
WEDNESDAY.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
...STRONG SURFACE WINDS WILL DOMINATE THIS TAF PERIOD...
LOW PRESSURE NEAR GEORGIAN BAY WILL EXPLOSIVELY DEEPEN AS IT WILL
LIFT TO WESTERN QUEBEC ON CHRISTMAS DAY. ITS ASSOCIATED COLD FRONT
WILL SWEEP ACROSS OUR REGION IN THE PROCESS...WITH STRONG WINDS AND
A RETURN TO MORE SEASONABLE WEATHER IN ITS WAKE. SFC WINDS WILL
INCREASE TO 20 TO 40 KTS WITH GUSTS AS HIGH AS 60 KTS FOR ALL OF THE
TAF SITES. THE GREATEST RISK FOR THE 60KT GUSTS WILL COME THROUGH
14Z.

OTHERWISE...MOST AREAS CAN EXPECT MVFR CIGS OVERNIGHT THROUGH THE
FIRST HALF OF CHRISTMAS DAY...WITH SOME IFR CIGS POSSIBLE ACROSS THE
HIGHER TERRAIN OF THE SRN TIER AND FINGER LAKES REGION. AS WE
PROGRESS THROUGH CHRISTMAS DAY...MOST AREAS WILL EXPERIENCE
IMPROVING CONDITIONS WITH SLOWLY DIMINISHING WINDS AND A RETURN TO
VFR CIGS.

OUTLOOK...
THURSDAY NIGHT...VFR WITH CONTINUING DIMINISHING WINDS.
FRIDAY AND SATURDAY...MAINLY VFR.
SATURDAY NIGHT...SCATTERED RAIN SHOWERS/POSSIBLE MVFR.
SUNDAY AND MONDAY...VFR/MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
LOW PRESSURE NEAR GEORGIAN BAY WILL EXPLOSIVELY DEEPEN AND LIFT TO
WESTERN QUEBEC...WHILE ITS TRAILING COLD FRONT WILL SWEEP OFF ACROSS
THE ADIRONDACKS AND ST LAWRENCE VALLEY. A SOLID PERIOD OF
SOUTHWESTERLY/WESTERLY GALES WILL SPREAD ACROSS THE LOWER GREAT
LAKES IN THE WAKE OF THE AFOREMENTIONED COLD FRONTAL PASSAGE.
WHILE IT IS NOT OUT OF THE QUESTION THAT SUSTAINED WINDS COULD
BRIEFLY REACH STORM FORCE ON EITHER LAKE ERIE OR LAKE ONTARIO
TONIGHT...AT THIS POINT THE DURATION OF ANY SUCH WINDS APPEARS TO BE
TOO SHORT TO BE WORTH AN UPGRADE.

LATER CHRISTMAS DAY AND CHRISTMAS NIGHT...WINDS WILL GRADUALLY
SUBSIDE TO ADVISORY LEVELS AS THE LOW LIFTS OUT ACROSS QUEBEC AND
FURTHER AWAY FROM OUR REGION. HIGH PRESSURE BUILDING IN ON FRIDAY
SHOULD THEN ALLOW WINDS AND WAVES TO FINALLY RELAX BELOW ADVISORY
THRESHOLDS BY FRIDAY EVENING.

LOOKING A BIT FURTHER OUT...ANOTHER AREA OF LOW PRESSURE WILL CUT
ACROSS THE CENTRAL GREAT LAKES OVER THE WEEKEND WITH A TIGHTENING
PRESSURE GRADIENT POTENTIALLY BRINGING ANOTHER ROUND OF ADVISORY-
LEVEL CONDITIONS.

&&

.HYDROLOGY...
THE COMBINATION OF RAIN AND SNOW MELT WILL CAUSE THE BLACK RIVER TO
RISE THIS EVENING THROUGH CHRISTMAS DAY. QPF SHOULD AVERAGE LESS
THAN A HALF INCH FOR THE BASIN...WITH LOCALLY HIGHER UPSTREAM OF
BOONVILLE WHERE RADAR HAS SHOWN SOME UPSLOPE ENHANCEMENT. MEANWHILE
TEMPERATURES FORECAST TO RISE INTO THE 50S SHOULD ALMOST COMPLETELY
MELT THE EXISTING SNOW PACK. THE WATERTOWN AND MCKEEVER FORECAST
POINTS ARE UNLIKELY TO REACH ACTION STAGE...BUT BOONVILLE SHOULD
CREST CLOSE OR ABOVE ACTION STAGE ON CHRISTMAS DAY.

&&

.TIDES/COASTAL FLOODING...
ON LAKE ERIE...A LAKESHORE FLOOD WARNING IS IN EFFECT FOR THE NY
SHORELINES OF LAKE ERIE. A SHARP COLD FRONT WILL MOVE UP THE LAKE
THIS EVENING AND BRING RAPIDLY INCREASING SOUTHWEST WINDS BEHIND IT.
LATEST HIGH RESOLUTION MODEL GUIDANCE CONTINUES TO SUGGEST THE
POTENTIAL FOR A FINE LINE OF CONVECTIVE SHOWERS ALONG THE SURFACE
COLD FRONT WITH A SUDDEN BURST OF WIND MOVING UP THE LAKE FROM
SOUTHWEST TO NORTHEAST. THIS SUDDEN CHANGE IN WIND DIRECTION AND
INCREASE IN SPEED IS A VERY GOOD SETUP FOR A SEICHE...WITH A
BUILDING SURGE OF WATER MOVING UP THE LENGTH OF THE LAKE. EXPECT
WATER LEVELS TO RISE TO NEAR THE FLOOD STAGE OF 8 FEET ABOVE LOW
WATER DATUM LATER TONIGHT. THIS WILL RESULT IN FLOODING OF LOW LYING
AREAS ALONG THE LAKE...ESPECIALLY IN HARBORS AND INLETS. WATER WILL
LIKELY WASH ACROSS ROUTE 5 IN ATHOL SPRINGS...POSSIBLY MAKING IT
IMPASSABLE.

ON LAKE ONTARIO...A LAKESHORE FLOODING WARNING IS IN EFFECT FOR THE
JEFFERSON COUNTY SHORE OF LAKE ONTARIO AND THE SAINT LAWRENCE RIVER.
WINDS BEHIND THE COLD FRONT WILL HAVE A LITTLE MORE SOUTHERLY
COMPONENT THAN NORMAL...RESULTING IN STRONG SOUTHWEST WINDS ON THE
LAKE. THIS DIRECTION IS FAVORED TO RESULT IN WATER RISING SEVERAL
FEET AT THE NORTHEAST END OF THE LAKE. THIS ALSO LINES UP WITH THE
NARROW ENTRANCE TO CHAUMONT BAY...WHERE WATER CAN PILE UP AND NOT
GET BACK OUT DUE TO THE NARROW BAY ENTRANCE. THIS SCENARIO HAS
RESULTED IN FLOODING IN THE PAST ON THE BAY. WATER WILL ALSO BE
FORCED DOWN THE SAINT LAWRENCE RIVER...WHICH MAY RESULT IN SOME
FLOODING IN THE THOUSAND ISLANDS REGION ON LOW LYING ISLANDS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...HIGH WIND WARNING UNTIL 4 PM EST THIS AFTERNOON FOR NYZ001>003-
     010>012-019-085.
     LAKESHORE FLOOD WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
     NYZ010-019-085.
     HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ007.
     LAKESHORE FLOOD WARNING UNTIL 4 PM EST THIS AFTERNOON FOR
     NYZ007.
     WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ004>006-008.
     WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NYZ013-014-020-
     021.
MARINE...GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LEZ020-040-041.
         GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LOZ030-
         042-062.
         GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LOZ043>045-
         063>065.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
         SLZ022-024.

&&

$$

SYNOPSIS...JJR/RSH
NEAR TERM...JJR/RSH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JJR/RSH
MARINE...JJR/RSH
HYDROLOGY...APFFEL
TIDES/COASTAL FLOODING...HITCHCOCK






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