Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 172047
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
347 PM EST WED DEC 17 2014

.SYNOPSIS...
TEMPERATURES WILL CONTINUE TO FALL TONIGHT AS COLD AIR SPREADS ACROSS
THE LOWER GREAT LAKES. OCCASIONAL SNOW SHOWERS OVERNIGHT
WILL ACCUMULATE A FEW INCHES ACROSS THE TUG HILL PLATEAU AND THE
HILLS OF THE SOUTHERN TIER WITH AN INCH OR LESS ELSEWHERE. SNOW WILL
TAPER OFF THROUGH THURSDAY AS THE ASSOCIATED AREA OF LOW PRESSURE
SHIFTS AWAY. HIGH PRESSURE WILL RETURN BY FRIDAY AND SATURDAY WITH
DRYING CONDITIONS AND NEAR-NORMAL TEMPERATURES.

&&

.NEAR TERM /THROUGH THURSDAY/...
COLD CYCLONIC FLOW WILL CONTINUE ACROSS THE LOWER GREAT LAKES
TONIGHT AS A COASTAL LOW SHIFTS ACROSS THE GULF OF MAINE.
TEMPERATURES THIS AFTERNOON WILL FALL FROM THE LOW TO MID 30S INTO
THE MID TO UPPER 20S OVERNIGHT. LINGERING SYNOPTIC MOISTURE THROUGH
10KFT PER BUFKIT PROFILES WILL THIN TO DOWN AROUND 5KFT OVERNIGHT.
RADARS CONTINUE TO SHOW SHOWER ACTIVITY ACROSS WESTERN AND CENTRAL
NEW YORK AT 3PM WHICH WILL CONTINUE THROUGH THE EVENING BUT THE
THINNING MOISTURE PROFILES AND WEAKENING LIFT WILL BRING REDUCED
CHANCES FOR PRECIP THROUGH EARLY THURSDAY.

THE BETTER ACCUMULATIONS OF SNOW TONIGHT WILL OCCUR ACROSS THE TUG
HILL AND HIGHER TERRAIN OF THE SOUTHERN TIER AND FINGER LAKES WHERE
SOME UPSLOPING AND WEAK LAKE ENHANCEMENT WILL COMBINE WITH THE
THINNING MOISTURE. OVERALL LAKE ENHANCEMENT WILL BE WEAK WITH LAKE
INDUCED EQUILIBRIUM LEVELS OF 4-5KFT DUE TO MARGINALLY COLD 850MB
TEMPS ONLY FALLING TO -8C TO -10C. OVERALL EXPECT JUST 1-3 INCHES IN
THE HIGHER TERRAIN WITH UP TO AN INCH ELSEWHERE. WINDS WILL ALSO
CONTINUE TO REMAIN GUSTY AVERAGING 20 TO 30 KNOTS AS COLD ADVECTION
HELPS TO MIX DOWN SOME STRONGER WINDS ALOFT. THIS WIND WILL COMBINE
WITH FALLING TEMPERATURES TONIGHT TO YIELD WIND CHILLS IN THE TEENS.

ON THURSDAY THE COASTAL LOW WILL SHIFT FURTHER AWAY ACROSS THE
CANADIAN MARITIMES. BUFKIT PROFILES SHOW NEARLY ALL THE LINGERING
MOISTURE WILL BE BELOW 5KFT WITH WEAK LIFT. THE WESTERLY FLOW WILL
CONTINUE TO KEEP THE HIGHEST CHANCES FOR SNOW SOUTHEAST OF THE LAKES
IN THE HIGHER TERRAIN WITH ANOTHER INCH OR TWO POSSIBLE. ELSEWHERE
ACROSS THE NIAGARA FRONTIER...FINGER LAKES AND FAR NORTH COUNTRY
ONLY EXPECT A CHANCE OF SOME LIGHT SNOW OR FLURRIES. IF CLOUD TOP
TEMPS DO NOT REACH COLDER THAN -10C THEN THE PTYPE MAY JUST END UP
BEING SOME DRIZZLE OR FREEZING DRIZZLE. A SLACKENING PRESSURE
GRADIENT WILL STILL KEEP SOME BREEZY WINDS ACROSS THE REGION WHICH
WILL COMBINE WITH TEMPERATURES ONLY REACHING INTO THE LOW 30S TO
KEEP WIND CHILLS IN THE TEENS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
LOW PRESSURE ACROSS THE CANADIAN MARITIMES WILL MAINTAIN AN NW FLOW
ACROSS THE REGION FOR THURSDAY NIGHT. ALOFT...THE REGION WILL REMAIN
ON THE BACK EDGE OF A CLOSED 500 MB LOW...WITH FORECAST SOUNDINGS
MAINTAINING AN INVERSION JUST BELOW 5K FEET. THIS WILL RESULT IN
MINIMAL LAKE INDUCED INSTABILITY...JUST ENOUGH TO PRODUCE VERY LIGHT
AND BARELY MEASURABLE PRECIPITATION. PROBABLY THE BIGGEST CONCERN
HERE IS THAT TEMPERATURES BENEATH THE INVERSION ARE FORECAST TO BE
AROUND -10C...WHICH IS PROBABLY JUST COLD ENOUGH FOR ICE NUCLEI TO
FORM AND KEEP PRECIPITATION AS LIGHT SNOW OR FLURRIES. IF CLOUD TOPS
ARE ANY WARMER...THEN FREEZING DRIZZLE WOULD BECOME A CONCERN SINCE
SURFACE TEMPERATURES WILL BE IN THE 20S THURSDAY NIGHT.

ON FRIDAY...HIGH PRESSURE WILL BEGIN TO NOSE IN FROM THE UPPER
LAKES...WITH WINDS DIMINISHING THROUGH THE DAY. THERE MAY BE SOME
LIGHT SNOW SHOWERS OR FLURRIES LINGERING DURING THE MORNING
HOURS...BUT EXPECT THESE TO TAPER OFF BY FRIDAY AFTERNOON. ALTHOUGH
WINDS WILL DIMINISH...THE INVERSION WILL LARGELY REMAIN IN
PLACE...WHICH SHOULD KEEPS SKIES MOSTLY CLOUDY FRIDAY AND FRIDAY
NIGHT. THIS WILL LIMIT DIURNAL TEMPERATURE VARIATION WITH HIGHS
FRIDAY IN THE UPPER 20S TO LOWER 30S. CONSIDERABLE CLOUDINESS FRIDAY
NIGHT WILL KEEP LOWS IN THE LOWER 20S IN MOST AREAS FRIDAY
NIGHT...BUT A PARTIAL CLEARING MAY ALLOW TEMPS TO DROP INTO THE
TEENS OR COLDER IN THE NORTH COUNTRY.

HIGH PRESSURE WILL BUILD ACROSS THE REGION ON SATURDAY...WITH FAIR
WEATHER ACROSS THE REGION. THE LINGERING INVERSION WILL RESULT IN
CONSIDERABLE CLOUD COVER DURING THE DAY...BUT MOISTURE BENEATH IT
WILL BE VERY SHALLOW WHICH SHOULD ALLOW FOR SOME BREAKS IN THE
CLOUDS ON SATURDAY. HIGHS WILL BE SLIGHTLY BELOW NORMAL...MOSTLY
IN THE LOWER 30S ACROSS THE REGION.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SATURDAY NIGHT THROUGH MONDAY NIGHT LOOKS RATHER UNEVENTFUL. 12Z
GFS/ECMWF/GGEM GUIDANCE CONTINUE TO BRING JUST A WEAK UPPER LEVEL
TROUGH ACROSS OUR REGION AND DO NOT PHASE THIS SHORTWAVE LIKE RUNS
EARLIER IN THE WEEK DID. THIS MAY BRING LIGHT SNOW SHOWERS OR
FLURRIES TO OUR REGION...BUT THERE IS INCREASING CONFIDENCE THAT
THERE WILL BE LITTLE IF ANY IMPACT FROM THIS SYSTEM. MOST 12Z
GUIDANCE DOES NOT EVEN BRING MEASURABLE QPF TO THE REGION.
OTHERWISE...WEAK SURFACE HIGH PRESSURE WILL DRIFT INTO NORTHERN NEW
ENGLAND...WITH PARTLY CLOUDY SKIES AND SEASONABLE TEMPERATURES.

AFTER THIS...A MUCH MORE ACTIVE WEATHER PATTERN IS LIKELY TO
DEVELOP. A CLOSED 500 MB LOW FORECAST TO BE NEAR THE GREAT LAKES
REGION TUESDAY MORNING WILL PIVOT A STRONG SHORTWAVE AROUND IT AND
SPARK STRONG LOW PRESSURE WHICH IS FORECAST TO TRACK UP THE EASTERN
STATES WRAP BACK INTO THE UPPER LOW. THIS GENERAL SCENARIO IS
SUPPORTED BY AN EXCELLENT CONSENSUS AMONG 12Z AND PREVIOUS RUNS OF
THE GFS/ECMWF. THIS WOULD RESULT IN AN ANOMALOUSLY DEEP LOW OF
AROUND 965MB ACROSS THE GREAT LAKES REGION ON WEDNESDAY.

ALTHOUGH THIS GENERAL SCENARIO IS LIKELY TO PLAY OUT...THE SPECIFIC
TRACK AND EVOLUTION OF THIS SYSTEM WILL DETERMINE OUR WEATHER...AND
THESE SPECIFICS ARE STILL UNCERTAIN. BASED ON THE CONSENSUS SOLUTION
THERE ARE A FEW CONCLUSIONS THAT CAN BE DRAWN. FIRST...THE MOST
SIGNIFICANT IMPACT FROM THIS SYSTEM IS LIKELY TO BE STRONG WINDS.
MODEL VARIABILITY MAKES IT DIFFICULT TO DETERMINE WHEN AND
WHERE...BUT STRONG TO DAMAGING WINDS MAY OCCUR IN SOME LOCATIONS
TUESDAY NIGHT AND/OR WEDNESDAY. ALSO...THE INITIAL ROUND OF
PRECIPITATION FROM THIS SYSTEM IS LIKELY TO BE RAIN ON TUESDAY NIGHT
OR WEDNESDAY. NEARLY ALL GUIDANCE HAS TEMPERATURES WELL TOO WARM TO
SUPPORT SNOW INITIALLY. SO AS IT STANDS NOW...CHRISTMAS EVE LOOKS TO
BE A RAINY AND WINDY DAY...WITH ABOVE NORMAL TEMPERATURES.

LOOKING A BIT FURTHER...TEMPERATURES SHOULD COOL CHRISTMAS DAY AND
BEYOND. THIS WILL PROBABLY CHANGE OVER PRECIPITATION TO SNOW BUT
SIGNIFICANT...OR ANY...ACCUMULATION IS STILL HIGHLY UNCERTAIN. THE
MOST NOTABLE WEATHER FEATURE FOR CHRISTMAS DAY MAY AGAIN BE STRONG
WINDS...WITH CONSENSUS GUIDANCE STALLING THE STRONG LOW NEAR THE
UPPER LAKES. AGAIN...IT IS IMPORTANT TO NOTE THAT MODEL GUIDANCE IS
LIKELY TO VARY FROM RUN TO RUN...AND SIGNIFICANT SHIFTS IN THE TRACK
AND POSITION OF THE LOW ARE STILL VERY POSSIBLE WITH THE FORECAST
STILL A WEEK AWAY.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
A COASTAL LOW WILL CONTINUE TO DEEPEN OVER THE GULF OF MAINE THIS
EVENING WHILE SHIFTING NORTH TOWARD THE CANADIAN MARITIMES. WESTERLY
FLOW ACROSS UPSTATE NEW YORK WITH THE PRESENCE OF LINGERING LOW
LEVEL MOISTURE WILL CONTINUE THE THREAT FOR SNOW SHOWERS AND
ASSOCIATED MVFR/IFR INTO TONIGHT. AS THE LOW SHIFTS FURTHER AWAY THE
MOISTURE WILL CONTINUE TO THIN AND CHANCES OF SNOW WILL LOWER LATER
OVERNIGHT AND THURSDAY. THE BEST CHANCES FOR SNOW AND REDUCED
VIS/CIG REMAINS ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER AND
TUG HILL EAST OF LAKE ONTARIO WITH SOME LAKE AND UPSLOPE ENHANCEMENT.

EXPECT MOST SITES TO IMPROVE TO MVFR ON THURSDAY. THERE IS A LOW
CHANCE FOR FREEZING DRIZZLE INSTEAD OF SNOW AS MOISTURE WILL BE THIN
BUT THE HIGHER CONFIDENCE LEANS TOWARD LIGHT SNOW.

OUTLOOK...
THURSDAY NIGHT...CHANCE OF LIGHT SNOW SHOWERS MAINLY EAST OF THE
LAKES AND MVFR.
FRIDAY...MVFR TO VFR WITH CHANCES OF SNOW SHOWERS ENDING.
SATURDAY TO MONDAY...VFR.

&&

.MARINE...
A COASTAL LOW WILL SHIFT NORTH ACROSS THE GULF OF MAINE TONIGHT. THE
SURFACE PRESSURE GRADIENT ACROSS THE LOWER GREAT LAKES ALONG WITH
COLD ADVECTION WILL CONTINUE STRONGER SOUTHWEST TO WESTERLY
WINDS...WHICH WILL MAINTAIN SMALL CRAFT ADVISORIES FOR BOTH LAKES
AND THE UPPER NIAGARA RIVER. HIGH PRESSURE BUILDS IN FRIDAY AND
SATURDAY WITH A RETURN TO MORE RELAXED CONDITIONS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THURSDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 10 PM EST THURSDAY FOR LOZ042.

&&

$$

SYNOPSIS...SMITH
NEAR TERM...SMITH
SHORT TERM...APFFEL
LONG TERM...APFFEL
AVIATION...SMITH
MARINE...SMITH







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