Area Forecast Discussion
Issued by NWS Buffalo, NY

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841
FXUS61 KBUF 101907
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
207 PM EST WED FEB 10 2016

.SYNOPSIS...
LOW PRESSURE WILL SLIDE EASTWARD INTO NEW ENGLAND TODAY WITH A
SURFACE TROUGH DROPPING SOUTH FROM LAKE ONTARIO TONIGHT. BEHIND THIS
TROUGH A PROGRESSIVELY COLDER ARCTIC AIRMASS WILL OVERSPREAD THE
REGION THROUGH THE WEEKEND...WITH ACCUMULATING LAKE SNOWS CONTINUING
TO THE LEE OF THE GREAT LAKES. THE MOST FRIGID CONDITIONS ARE
EXPECTED ON SATURDAY...WHEN HIGHS WILL LIKELY STRUGGLE TO CLIMB MUCH
ABOVE ZERO...AND WIND CHILLS WILL BE AT DANGEROUSLY LOW LEVELS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN AMPLIFIED UPPER LEVEL TROUGH LIES ACROSS THE EASTERN STATES THIS
AFTERNOON WITH A SURFACE LOW SHIFTING INTO SOUTHERN QUEBEC. TRAILING
THIS LOW IS A WEAK SURFACE TROUGH THAT WILL BRING A PROGRESSIVELY
COLDER AIRMASS INTO THIS COMING WEEKEND. REGIONAL RADARS ARE SHOWING
LAKE EFFECT SNOWS SOUTH AND EAST OF THE GREAT LAKES AS COLDER AIR
CROSSES THE STILL OPEN WATERS. ACROSS WESTERN NEW YORK...LAKE SNOWS
CONTINUE THIS AFTERNOON OFF LAKE ERIE AND LAKE ONTARIO WITH LAKE
EFFECT WARNINGS AND ADVISORIES IN EFFECT. RADAR ESTIMATES SNOW RATES
OFF LAKE ERIE WITHIN MULTIPLE NARROW BANDS RANGING FROM A HALF TO
ONE INCH WITH A PERSISTENT MORE IMPRESSIVE SNOW BAND WITH 1 TO 2
INCHES PER HOUR RATES HUGGING THE LAKE ONTARIO SHORELINE ACROSS
NIAGARA...ORLEANS AND MONROE COUNTIES AND EXTENDING EAST BUT AT
WEAKER RATES ACROSS WAYNE...NORTHERN CAYUGA AND SOUTHERN OSWEGO
COUNTIES. THE MORE IMPRESSIVE SNOW RATES ACROSS THE IMMEDIATE LAKE
ONTARIO SHORELINE ARE DO TO SURFACE CONVERGENCE AHEAD OF THE
APPROACHING SURFACE TROUGH AND AN UPSTREAM MOISTURE CONNECTION TO
GEORGIAN BAY.

OUTSIDE OF THE ABOVE MENTIONED LAKE EFFECT...THE MOIST CYCLONIC FLOW
WILL CONTINUE A NEED FOR CHANCE TO LIKELY POPS FOR LIGHT SNOW AHEAD
OF THE APPROACHING SURFACE TROUGH.

REGARDING THE AREAS OF ENHANCED SNOWFALL MENTIONED ABOVE...

OFF LAKE ERIE...THE STEADIEST LAKE AND TERRAIN-ENHANCED SNOWS WILL
TEND TO FOCUS MOST ACROSS THE CHAUTAUQUA RIDGE REGION OF SOUTHERN
ERIE/CHAUTAUQUA/CATTARAUGUS COUNTIES THROUGH THE NEAR TERM
PERIOD...WITH THE ACTIVITY BECOMING INCREASINGLY LAKE-DRIVEN OVER
TIME AS OUR AIRMASS GROWS COLDER. THE HEAVIEST AND MOST PERSISTENT
SNOWS ARE EXPECTED TONIGHT TIED TO THE PASSAGE OF THE SURFACE TROUGH
AND AN UPSTREAM CONNECTION TO LAKE HURON. WITH LAKE EQLS OF 8-10 KFT
IN PLACE AND FAVORABLE MOISTURE LYING BELOW THAT EXPECT WARNING-
CRITERIA SNOWFALL AMOUNTS OF UP TO 2 FEET ACROSS THE ABOVE MENTIONED
REGION BETWEEN TODAY AND THURSDAY. SOME OF THE HEAVIER SNOWS WILL
ALSO CONTINUE TO OCCASIONALLY VENTURE INTO WESTERN WYOMING COUNTY AT
TIMES...WHERE A LAKE EFFECT SNOW ADVISORY REMAINS IN EFFECT.

OFF OF LAKE ONTARIO...MODELS INDICATE THE CORE OF THESE SNOWS WILL
CONTINUE ALONG THE SOUTHERLY LAKE SHORE WITH RATES EVENTUALLY
BECOMING MORE IMPRESSIVE INTO THE WAYNE-NORTHERN CAYUGA-SOUTHERN
OSWEGO COUNTY CORRIDOR THIS EVENING AS THE LOW LEVEL FLOW BECOMES
BETTER ALIGNED OUT OF THE WEST-NORTHWEST BEHIND THE SURFACE TROUGH.
AS WITH THE LAKE ERIE ACTIVITY...A PRETTY FAVORABLE ENVIRONMENT IN
PLACE WITH LAKE EQLS OF 8-10 KFT PRESENT AND SUFFICIENT MOISTURE
LYING BELOW THAT TO RESULT IN WARNING-CRITERIA SNOWFALL AMOUNTS
WHERE THE SNOWS WILL BE MOST PERSISTENT TONIGHT THROUGH THURSDAY.
MEANWHILE NORTH OF THIS WARNING AREA...LAKE EFFECT SNOW ADVISORIES
ARE IN EFFECT THROUGH TODAY FOR WEAKER SNOWFALL OVER THE TUG HILL
REGION.

AS FOR TEMPERATURES...EXPECT THESE TO STEADILY DROP THROUGH THIS
EVENING INTO THE 10-15 RANGE ACROSS MUCH OF THE AREA BY TONIGHT. BY
LATE TONIGHT...READINGS MAY EVEN FALL INTO THE UPPER SINGLE DIGITS
ACROSS PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
ON THURSDAY THE SURFACE LOW WILL MOVE EAST INTO THE CANADIAN
MARITIMES WITH THE MID LEVEL TROUGH CROSSING THE LOWER LAKES REGION.
ASCENT AND DEEPER MOISTURE ASSOCIATED WITH THE MID LEVEL TROUGH WILL
PRODUCE A FEW SCATTERED SNOW SHOWERS OUTSIDE OF LAKE EFFECT AREAS...
ESPECIALLY EAST OF LAKE ONTARIO WHERE FORCING WILL BE STRONGEST. THE
MAIN FOCUS THURSDAY AND THURSDAY NIGHT WILL BE WITH THE ONGOING LAKE
EFFECT SNOW SOUTHEAST OF THE LAKES.

OFF LAKE ERIE...

LAKE INDUCED INSTABILITY REMAINS STRONG THROUGH THE PERIOD WITH
EQUILIBRIUM LEVELS AROUND 10K FEET. BOUNDARY LAYER FLOW WILL
CONTINUE TO BE NORTHWEST ON THURSDAY...WHICH WILL LIMIT THE FETCH
ACROSS LAKE ERIE BUT ALSO PROVIDE FAVORABLE UPSLOPE FLOW ALONG THE
CHAUTAUQUA RIDGE. MESOSCALE MODEL GUIDANCE CONTINUES TO SUGGEST AN
UPSTREAM CONNECTION TO LAKE HURON ESPECIALLY DURING THE FIRST HALF
OF THURSDAY. THIS WILL LIKELY ENHANCE SNOWFALL RATES ACROSS PORTIONS
OF CHAUTAUQUA COUNTY...MOST LIKELY THE FAR SOUTHWEST CORNER OF THE
COUNTY NEAR FINDLAY LAKE GIVEN THE FLOW DIRECTION. THIS UPSTREAM
CONNECTION WILL END LATER THURSDAY AFTERNOON AS BOUNDARY LAYER FLOW
BACKS ACROSS SOUTHERN LAKE HURON. THE END OF THE UPSTREAM CONNECTION
AND ALSO A WEAK SURFACE RIDGE BRIEFLY BUILDING OVER LAKE ERIE SHOULD
WEAKEN THE LAKE ERIE LAKE EFFECT LATER THURSDAY AFTERNOON AND
EVENING.

EXPECT ADDITIONAL ACCUMULATIONS OF 3-6 INCHES ON THURSDAY IN
PERSISTENT BANDS ACROSS THE WESTERN SOUTHERN TIER...WITH THE HIGHER
AMOUNTS FOCUSED ON THE UPSLOPE AREAS OF THE CHAUTAUQUA RIDGE AND
ALSO WHERE THE LAKE HURON CONNECTION FORMS. THIS WILL BRING STORM
TOTALS FROM LATE TUESDAY EVENING THROUGH LATE THURSDAY AFTERNOON
INTO THE 12-18 INCH RANGE IN THE MOST PERSISTENT BANDS...MAINLY IN A
RELATIVELY SMALL AREA OF UPSLOPE FLOW JUST INLAND FROM THE
LAKESHORE.

LATER THURSDAY NIGHT AND FRIDAY BOUNDARY LAYER FLOW WILL BACK TO THE
WEST AND EVENTUALLY WSW AS A SURFACE LOW RACES EAST ACROSS SOUTHERN
ONTARIO IN ADVANCE OF THE ARCTIC FRONT. THE BACKING WINDS WILL ALLOW
LAKE EFFECT SNOW TO RE-ORGANIZE LATE THURSDAY NIGHT AS FETCH
INCREASES ACROSS THE LAKE. INSTABILITY REMAINS STRONG THROUGH FRIDAY
WITH EQUILIBRIUM LEVELS AROUND 10K FEET...ALTHOUGH THE AIRMASS MAY
DRY OUT IN THE TOP OF THAT LAYER. EXPECT THE LAKE EFFECT SNOW TO
MAKE IT INTO THE SOUTHERN HALF OF THE BUFFALO METRO AREA FOR A TIME
FRIDAY MORNING...ALSO EXTENDING INTO PORTIONS OF SOUTHERN GENESEE
AND WYOMING COUNTIES. THIS BAND OF SNOW MAY PRODUCE AT LEAST
MODERATE ACCUMULATIONS...WITH UNCERTAINTIES STILL ON THE IMPACT OF
SOMEWHAT DRIER AIR ALOFT AND INCREASING SHEAR WITH THE APPROACH OF
THE ARCTIC FRONT. THIS MAY EVENTUALLY REQUIRE ADDITIONAL LAKE EFFECT
HEADLINES AS THE DETAILS BECOME MORE CERTAIN.

OFF LAKE ONTARIO...

SIMILAR TO LAKE ERIE...LAKE INDUCED INSTABILITY REMAINS STRONG
THROUGH THE PERIOD WITH EQUILIBRIUM LEVELS AROUND 10K FEET. ON
THURSDAY BOUNDARY LAYER FLOW WILL REMAIN NORTHWEST...WITH SNOW ALONG
MUCH OF THE SOUTH SHORE OF THE LAKE. THE 290 WIND DIRECTION SUGGESTS
THERE WILL BE A RELATIVE MAX IN COVERAGE AND INTENSITY ACROSS
WAYNE/NORTHERN CAYUGA/SOUTHERN OSWEGO COUNTIES WHERE THE FETCH IS
MAXIMIZED. MESOSCALE MODEL GUIDANCE CONTINUES TO SUGGEST THE
UPSTREAM CONNECTION TO GEORGIAN BAY WILL RESIDE TO THE WEST OF
ROCHESTER ON THURSDAY. EXPECT ADDITIONAL SNOW AMOUNTS ON THURSDAY OF
3 TO 6 INCHES IN THE MOST FAVORED AREAS OF NORTHERN/EASTERN WAYNE
COUNTY INTO NORTHERN CAYUGA AND FAR SOUTHERN OSWEGO COUNTIES.
FARTHER WEST EXPECT 1 TO 3 INCHES ALONG THE SHORE FROM ROCHESTER TO
PORTIONS OF ORLEANS AND EASTERN NIAGARA COUNTIES. THE WILDCARD IN
THIS AREA IS THE POTENTIAL FOR THE UPSTREAM GEORGIAN BAY CONNECTION
WHICH MAY LOCALLY ENHANCE TOTALS.

THURSDAY NIGHT MAY VERY WELL BE THE TIME OF MOST INTENSE SNOWFALL
FOR A SMALL AREA SOUTHEAST OF LAKE ONTARIO AS THE BAND CONSOLIDATES
WITH BACKING FLOW OVERNIGHT. THE NORTHWEST FLOW WILL BECOME MORE WNW
AND EVENTUALLY WESTERLY...INCREASING FETCH AND CONVERGENCE ALONG THE
LENGTH OF THE LAKE. THIS WILL ALLOW SNOW TO END FROM ROCHESTER
WESTWARD DURING THE EVENING AS THE BAND LIFTS NORTH AND OFFSHORE.
FARTHER EAST...EXPECT AN INTENSIFYING SINGLE BAND OF SNOW OVER
EASTERN WAYNE AND NORTHERN CAYUGA COUNTIES FROM LATE EVENING THROUGH
THE EARLY OVERNIGHT HOURS. TOWARD DAYBREAK FRIDAY BOUNDARY LAYER
FLOW QUICKLY BACKS FURTHER TO WEST AND WSW...WHICH WILL CARRY THE
BAND RAPIDLY NORTHEAST ACROSS OSWEGO COUNTY. ADDITIONAL AMOUNTS
THURSDAY NIGHT SHOULD PEAK FROM SODUS INTO NORTHERN CAYUGA COUNTY
WITH ANOTHER 8-10 INCHES POSSIBLE. EXPECT A QUICK 2-4 INCHES ACROSS
OSWEGO COUNTY LATE THURSDAY NIGHT AS THE BAND MOVES RAPIDLY ACROSS
THE COUNTY.

ON FRIDAY BOUNDARY LAYER FLOW BECOMES ALIGNED FROM THE SOUTHWEST...
WHICH WILL ALLOW THE LAKE EFFECT SNOW TO BECOME BETTER ORGANIZED
AGAIN ACROSS JEFFERSON AND NORTHERN LEWIS COUNTIES. LAKE INDUCED
EQUILIBRIUM LEVELS REMAIN HIGH...ALTHOUGH SHEAR MAY INCREASE WITH
THE APPROACH OF THE ARCTIC FRONT. THIS BAND MAY PRODUCE MODERATE
ACCUMULATIONS NORTHEAST OF LAKE ONTARIO FRIDAY. THIS MAY EVENTUALLY
REQUIRE ADDITIONAL LAKE EFFECT HEADLINES ONCE THE DETAILS BECOME
MORE CERTAIN.

LAST BUT NOT LEAST...A POWERFUL ARCTIC FRONT WILL SURGE SOUTH ACROSS
THE REGION FRIDAY EVENING. THIS ARCTIC FRONT WILL LIKELY CAPTURE AND
MERGE WITH THE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO...WITH A VERY
HEAVY SNOW SQUALL PASSING SOUTH ACROSS MUCH OF THE REGION. THIS WILL
LIKELY PRODUCE AN INCH OR TWO OF SNOW IN MANY AREAS...WITH LOCALLY
HIGHER AMOUNTS SOUTHEAST OF THE LAKES WHERE THE LAKE CONTRIBUTION
MAXIMIZES. BEHIND THE ARCTIC FRONT...MULTIPLE STREAMERS OF LAKE
EFFECT SNOW SHOWERS WILL DEVELOP SOUTH OF THE LAKES LATE FRIDAY
NIGHT AS FLOW BECOMES NORTHWEST AND EVENTUALLY NNW.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A FRIGID ARCTIC AIRMASS WILL TAKE HOLD OF THE EASTERN GREAT LAKES
AND NEW ENGLAND SATURDAY AS 850MB TEMPS PLUMMET TO AN AVERAGE OF
-32C. TO PUT THIS IN PROSPECTIVE...THE COLDEST TEMPERATURE EVER
RECORDED AT 850MB ON A KBUF SOUNDING IN THE MONTH OF FEBRUARY IS
-28C...AND THE COLDEST EVER RECORDED FOR ANY MONTH IS -32C.
TEMPERATURES WILL DROP INTO THE SINGLE DIGITS ABOVE AND BELOW ZERO BY
EARLY SATURDAY MORNING DEPENDING ON LOCATION. ANY ABOVE ZERO
TEMPERATURES FIRST THING IN THE MORNING WILL LIKELY BE REPLACED BY
SINGLE DIGITS BELOW ZERO EVERYWHERE BY MIDDAY AND AFTERNOON AS THE
CORE OF THE COLDEST AIR ALOFT CROSSES THE AREA. LOWS WILL BE WELL
BELOW ZERO SATURDAY NIGHT...WITH -20 OR BETTER ACROSS THE NORTH
COUNTRY WITH NO MODERATING LAKE INFLUENCE. THE COMBINATION OF
MODERATE WINDS AND FRIGID TEMPERATURES WILL PRODUCE DANGEROUSLY COLD
WIND CHILLS LATE FRIDAY NIGHT THROUGH EARLY SUNDAY MORNING.

THE FRIGID NORTH FLOW OVER THE LAKES WILL PRODUCE WIDESPREAD LAKE
EFFECT SNOW SHOWERS ACROSS WESTERN AND CENTRAL NY. DESPITE THE
EXTREME INSTABILITY...AIRMASSES THIS COLD ARE ALSO VERY DRY AND
TEMPERATURES BECOME TOO COLD FOR DENDRITES. THIS WILL FORCE
SNOWFLAKES TO BE VERY SMALL AND LIMIT ACCUMULATIONS...ALTHOUGH
SEVERAL INCHES ARE LIKELY SOUTH OF BOTH LAKES. THE LAKE EFFECT SNOW
WILL DIMINISH IN COVERAGE AND INTENSITY SUNDAY...BUT NOT END
ALTOGETHER UNTIL SUNDAY NIGHT AS THE HIGH CRESTS OVERHEAD.

THE FRIGID TEMPERATURES WILL BE SHORT LIVED AS STRONG WARM ADVECTION
BRINGS TEMPS BACK TO AVERAGE BY MONDAY AND TUESDAY. THE NEXT
SYNOPTIC SYSTEM WILL MOVE THE REGION BY MONDAY OR TUESDAY WITH A
CHANCE OF SNOW...ALTHOUGH THE GFS AND ECMWF DIFFER A GOOD DEAL ON
THE TIMING AND TRACK DETAILS.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
COLD AND MOIST FLOW WITHIN AN UPPER LEVEL TROUGH ACROSS THE GREAT
LAKES IS CONTRIBUTING TO WIDESPREAD LIGHT SNOWFALL TODAY WITH
ENHANCED LAKE EFFECT SNOWS SOUTH AND EAST OF THE LAKES. OVERALL
EXPECT IFR OR LOWER CIGS/VIS IN LAKE EFFECT SNOWS WITH MVFR CIGS
OUTSIDE OF THE LAKE SNOWS.

TONIGHT INTO THURSDAY...EXPECT CONTINUED IFR/LIFR IN AREAS OF
HEAVIER LAKE EFFECT SNOW EAST AND SOUTH OF THE LAKES...WITH MVFR/IFR
IN SCATTERED TO NUMEROUS SNOW SHOWERS ELSEWHERE. WINDS WILL SHIFT
MORE NORTHWESTERLY TONIGHT BEHIND A SURFACE TROUGH.

OUTLOOK...
THURSDAY NIGHT...MVFR/IFR IN SHIFTING LAKE EFFECT SNOW
SHOWERS...EAST AND SOUTH OF THE LAKES.
FRIDAY...IFR/MVFR WITH SNOW SHOWERS LIKELY...AND AREAS OF HEAVIER
LAKE EFFECT SNOW EAST OF THE LAKES.
SATURDAY...IFR/MVFR IN LAKE EFFECT SNOW SHOWERS SOUTH OF THE
LAKES... WITH MVFR/VFR ACROSS THE NORTH COUNTRY.
SUNDAY...CHANCE OF IFR/MVFR IN WEAKENING LAKE EFFECT SNOW SHOWERS
SOUTH OF THE LAKES. MONDAY...CHANCE OF IFR/MVFR WITH A CHANCE OF
SNOW SHOWERS.

&&

.MARINE...
A BRISK FLOW OF PROGRESSIVELY COLDER ARCTIC AIR WILL CONTINUE TO
OVERSPREAD THE REGION THROUGH THE WEEKEND...RESULTING IN A PROLONGED
PERIOD OF ADVISORY-WORTHY WINDS AND WAVES ACROSS THE LOWER LAKES.

IN ADDITION TO THE ABOVE...THE PASSAGE OF AN ARCTIC COLD FRONT
FRIDAY EVENING WILL ALSO USHER IN A TRULY FRIGID AIRMASS FOR LATER
FRIDAY NIGHT AND THE UPCOMING WEEKEND...WHICH IN CONJUNCTION WITH
THE EXPECTED BRISK WINDS WILL RESULT IN A GREATLY HEIGHTENED
POTENTIAL FOR HEAVY FREEZING SPRAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     NYZ007-008.
     LAKE EFFECT SNOW WARNING UNTIL 4 AM EST FRIDAY FOR NYZ004>006.
     LAKE EFFECT SNOW WARNING UNTIL 4 PM EST THURSDAY FOR
     NYZ001>003-019-020-085.
     LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
     NYZ012.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
         LEZ020.
         SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LOZ042.

&&

$$

SYNOPSIS...JJR/SMITH
NEAR TERM...JJR/SMITH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JJR/SMITH
MARINE...JJR/SMITH



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