Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 291748
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1248 PM EST THU JAN 29 2015

.SYNOPSIS...
A STORM SYSTEM WILL TRACK ACROSS THE GREAT LAKES REGION TODAY
SPREADING SNOW ACROSS OUR REGION THIS AFTERNOON THROUGH TOMORROW.
GREATEST SNOWFALL TOTALS WILL BE FOUND ACROSS THE HIGHER TERRAIN
EAST OF BOTH LAKES. ANOTHER AREA OF HIGH PRESSURE WILL THEN BRING A
RETURN OF FAIR...BUT COLD WEATHER FOR THE START OF THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS THIS LATE MORNING DISPLAY A BAND OF PRECIPITATION
ACROSS THE WESTERN SOUTHERN TIER. BASED ON SURFACE OBSERVATIONS FROM
ERIE, PA...AND SPOTTERS THIS BAND OF PRECIPITATION IS IN THE FORM OF
FREEZING RAIN...AND SLEET. NEAR THE LAKESHORE WHERE A SOUTHEAST
WIND HAS WARMED THE LAKESHORE INTO THE MID AND UPPER 30S...SOME
PLAIN RAIN IS POSSIBLE THROUGH THE EARLY AFTERNOON. WE WILL START
THE WINTER WEATHER ADVISORY FOR SW NYS NOW...AND UPDATE THE GRIDS
WITH A WINTRY MIX FOR SEVERAL HOURS. AS THE WARM NOSE ALOFT
ENCOUNTERS COLDER...AND DRIER AIR TO THE NORTH EXPECT SNOW TO BE THE
PREDOMINATE P-TYPE...THOUGH SOME SLEET COULD REACH AS FAR NORTHWARD
AS THE NIAGARA FRONTIER THIS LATE MORNING AND EARLY AFTERNOON.

FOR THIS AFTERNOON...THE CENTER OF THE STORM SYSTEM LOOKS TO SHIFT
ACROSS LAKE ERIE 18-00Z THEN SHIFT NORTH OF LAKE ONTARIO 00-06Z.
MODEL CONSENSUS GENERALLY HOLDS OFF ANY SNOW ACROSS WESTERN NEW YORK
UNTIL THE 18-21Z TIME FRAME WHEN THE LOW LEVELS FINALLY BECOME
SATURATED. SURFACE TEMPERATURES THIS AFTERNOON WILL RANGE THROUGH
THE LOWER 30S WHERE INITIALLY SOME OF THE SNOW WILL STRUGGLE TO
ACCUMULATE. SNOW WILL THEN BEGIN TO FALL ACROSS CENTRAL NEW YORK AND
EAST OF LAKE ONTARIO IN THE 21-00Z TIME FRAME BUT TEMPS HERE LOOK TO
ONLY HOVER AROUND 30 SO SNOWS MAY NOT HAVE AS HARD OF A TIME
ACCUMULATING BEFORE SUNSET.  ANY ACCUMULATIONS THAT DO OCCUR DURING
THE AFTERNOON/EARLY EVENING SHOULD BE HELD TO LESS THAN AN INCH AS
THE BEST SYNOPTIC MOISTURE AND LIFT LIE BELOW/WARMER THAN THE PRIME
DENDRITIC SNOW GROWTH ZONE ALOFT YIELDING WEAK SNOW-LIQUID RATIOS.

HIGHER CONFIDENCE FOR ACCUMULATING SNOWS HOLDS OFF UNTIL THIS
EVENING WHEN THE SYSTEMS COLD FRONT CROSSES OUR REGION AND COLD
ADVECTION HELPS TO LOWER THE HEIGHT OF THE FAVORABLE DENDRITIC SNOW
GROWTH ZONE CLOSER TO THE SURFACE. WINDS WILL VEER TO THE NORTHWEST
WITH SOME BREEZY WINDS EXPECTED OVERNIGHT. THE LOWERING OF THE PRIME
DENDRITIC SNOW GROWTH ZONE SHOULD HELP TO INCREASE SNOW-LIQUID RATIOS
CLOSER TO 15 OR 18:1. THIS COMBINED WITH A BLEND OF MODEL QPF SHOULD
YIELD AN ADDITIONAL 2-3 INCHES ACROSS WESTERN NEW YORK TONIGHT WITH
3-7 EAST AND SOUTHEAST OF LAKE ONTARIO. MODEL QPF AND THUS SNOW
TOTALS ARE LOWEST ACROSS THE GENESEE VALLEY...NIAGARA FRONTIER AND
WESTERN FINGER LAKES WITH TOTALS BY FRIDAY MORNING ONLY 1-3 INCHES.
HAVE CONTINUED THE WINTER WEATHER ADVISORIES FOR THE SOUTHERN TIER
AND EAST OF LAKE ONTARIO WHILE ADDING EASTERN WAYNE AND NORTHERN
CAYUGA COUNTIES SOUTHEAST OF LAKE ONTARIO WHERE SOME LAKE
ENHANCEMENT LATE TONIGHT MAY HELP BOOST THESE COUNTIES OVER ADVISORY
LEVELS. OTHERWISE TEMPS TONIGHT WILL NOT BE AS COLD AS RECENT NIGHTS
WITH CLOUD COVER AND WIDESPREAD SNOW.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
LOW PRESSURE WILL MOVE ACROSS NEW ENGLAND ON FRIDAY AND SET UP A
NORTHERLY COLD AIR ADVECTION FLOW ACROSS OUR REGION. TEMPERATURES
WILL FALL THROUGHOUT THE DAY...DROPPING THROUGH THE TEENS AND INTO
THE SINGLE DIGITS DURING THE AFTERNOON. THE COMBINATION OF DROPPING
TEMPERATURES AND BRISK WINDS MAY PRODUCE WIND CHILL ADVISORY
CRITERIA WIND CHILLS IN MANY AREAS LATE FRIDAY THROUGH SATURDAY
MORNING...WITH WARNING CRITERIA NOT OUT OF THE QUESTION ACROSS THE
NORTH COUNTRY. CLOUDS AND SOME WIND WILL LIMIT RADIATIONAL COOLING
SOUTH OF LAKE ONTARIO WITH LOWS NEAR OR JUST BELOW ZERO IN MOST
AREAS. LIGHTER WINDS AND SOME CLEAR SKIES SHOULD ALLOW TEMPERATURES
TO DROP TO 10 TO 15 BELOW IN THE NORTH COUNTRY.

THE COLD NORTHWEST FLOW WILL ALSO SUPPORT A WIDE SWATH OF WEAK
MULTIPLE BAND LAKE EFFECT SNOW SHOWERS SOUTHEAST OF LAKE
ONTARIO...WITH SOME ACROSS THE WESTERN SOUTHERN TIER AS WELL FROM
UPSLOPE FLOW AND LIMITED MOISTURE FROM LAKE HURON AND THE FEW OPEN
PATCHES ON LAKE ERIE. THE COLD AIR WILL BE SHALLOW WITH AN INVERSION
AROUND 5K FEET...HOWEVER IT WILL BE -20C OR COLDER BENEATH THIS
INVERSION WHICH IS PLENTY COLD TO SUPPORT DENDRITIC SNOW GROWTH.
MOISTURE WILL BE A LIMITING FACTOR GIVEN THE SHORT FETCH...BUT A
SHORTWAVE TRAILING THE SURFACE LOW SHOULD PROVIDE SOME MOISTURE AS
IT MOVES ACROSS THE REGION FRIDAY. EXPECT ANOTHER 1 TO 3 INCHES
FRIDAY THROUGH FRIDAY EVENING SOUTHEAST OF BOTH LAKES...WITH THE
HIGHER AMOUNTS LIKELY TO BE FROM THE EASTERN SUBURBS OF ROCHESTER TO
OSWEGO COUNTY GIVEN THE WIND DIRECTION. LAKE EFFECT SNOW SHOWERS
SHOULD TAPER OFF TO VERY LIGHT SNOW SHOWERS OR FLURRIES LATE FRIDAY
NIGHT WITH DIMINISHING MOISTURE AND A LOWERING INVERSION.

HIGH PRESSURE WILL BUILD FROM THE OHIO VALLEY AND INTO THE REGION
SATURDAY WITH MAINLY DRY WEATHER. TEMPERATURES WILL REMAIN WELL
BELOW AVERAGE SATURDAY WITH HIGHS ONLY IN THE TEENS IN MOST AREAS
AND SINGLE NUMBERS ACROSS THE NORTH COUNTRY.

GUIDANCE IS A BIT STRONGER WITH A CLIPPER LOW TO THE NORTH WITH THE
00Z NAM/GFS/GGEM DROPPING ANOTHER A COLD FRONT ACROSS OUR REGION.
THIS WILL BE A MOISTURE STARVED SYSTEM...BUT IT MAY BE ENOUGH FOR
ANOTHER ROUND OF LIGHT LAKE EFFECT SNOW SHOWERS SATURDAY NIGHT.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
A CONSENSUS OF 00Z GUIDANCE CONTINUES THE TRENT OF BACKING OFF ON A
POTENTIALLY SIGNIFICANT SNOW EVENT SUNDAY NIGHT INTO MONDAY. THE 00Z
GFS/ECMWF BOTH TRACK THIS LOW SOUTH OF THE AREA...BUT THE GGEM STILL
HAS IT AS WELL AS SEVERAL GEFS ENSEMBLE MEMBERS. AT THIS
POINT...THERE IS AN INCREASING PROBABILITY FOR A WEAKER AND FURTHER
SOUTH TRACK...BUT THERE STILL IS A CHANCE THE SYSTEM WILL DEVELOP
AND IMPACT THE REGION. HAVE TRENDED POPS SLIGHTLY DOWN TO REFLECT
THE LATEST MODEL GUIDANCE.

REGARDLESS OF WHETHER THE SYSTEM MATERIALIZES OR NOT...ANOTHER
STRONG PUSH OF COLD AIR WILL ARRIVE EARLY NEXT WEEK. IF THE
NON-STORM 12Z GFS AND ECMWF ARE CORRECT...COLD AIR WOULD REMAIN
ENTRENCHED ACROSS THE REGION SUNDAY AND MONDAY WITH THE COLDEST AIR
MOVING IN MONDAY NIGHT AND TUESDAY. COLD AIR REMAINS THROUGH MIDWEEK
AND THERE WILL BE AT LEAST SOME LAKE EFFECT POTENTIAL SOUTHEAST AND
EAST OF LAKE ONTARIO...BUT GIVEN THE MODEL DIFFERENCES BEFORE
THAT...THERE IS TOO MUCH UNCERTAINTY FOR ANY TIMING AND INTENSITY
DETAILS YET.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT 18Z VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION...THOUGH
THE IMPACTS FROM THE CENTRAL GREAT LAKES STORM SYSTEM...ARE UPON WNY
AS LIGHT PRECIPITATION IS BEGINNING TO FALL ACROSS WNY. A WEALTH OF
DRY AIR AT THE LOWER LEVELS WILL KEEP THIS PRECIPITATION LIGHT
THROUGH THE FIRST 3-6 HOURS OF THE TAF PERIOD. P-TYPE WILL BE TRICKY
AS A WARM NOSE JUST ABOVE THE SURFACE MAY ALLOW FOR SOME SLEET AND
EVEN PLAIN RAIN/DRIZZLE FOR A TIME THIS AFTERNOON ACROSS
KJHW/KBUF/KIAG. AS PRECIPITATION INTENSITY INCREASES THIS AFTERNOON
EXPECT A CHANGE OVER BACK TO PLAIN SNOW...WITH THE SNOW IMPACTING
ALL TAF SITES THIS EVENING AND OVERNIGHT.

A PERIOD OF IFR OR LOWER VSBYS ARE EXPECTED WITHIN THIS
SNOW...THOUGH CIGS NEAR THE LAKES SHOULD REMAIN LARGELY MVFR...BUT
OCCASIONALLY DIP TO IFR ACROSS THE SOUTHERN TIER.

A COLD FRONT WILL CROSS THE REGION MID EVENING TOWARDS THE WEST AND
JUST PAST MIDNIGHT EAST OF LAKE ONTARIO. WINDS WILL VEER AROUND TO
WEST...THEN LATER NORTHWEST BEHIND THE COLD FRONT AND OCCASIONALLY
GUST 20 TO 25 KNOTS. LIGHT SNOW WILL CONTINUE THROUGH THE END OF THE
TAF PERIOD...BECOMING MORE FOCUSED SOUTH OF LAKE ONTARIO. ANY OF
THESE SNOW SHOWERS MAY BRING IFR VSBYS...IN AN OTHERWISE
PREDOMINATELY MVFR FLIGHT CONDITIONS.

OUTLOOK...
FRIDAY NIGHT...A CHANCE OF SNOW SHOWERS SOUTHEAST OF THE
LAKES.
SATURDAY...NO SIGNIFICANT WEATHER EXPECTED.
SUNDAY AND MONDAY....AREAS OF MVFR IN A CHANCE OF SNOW SHOWERS
SOUTH OF LAKE ONTARIO.
TUESDAY...AREAS OF MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
HIGH PRESSURE PUSHES EAST ACROSS NEW ENGLAND TODAY...A STORM SYSTEM
WILL APPROACH FROM THE WEST AND INCREASE THE SFC PRESSURE GRADIENT
ENOUGH TO FRESHEN THE SOUTHEASTERLY WINDS THIS AFTERNOON. THIS
SCENARIO WILL KEEP THE MOST SIGNIFICANT WAVES IN CANADIAN WATERS.
THIS SHOULD KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY
LEVELS...ALTHOUGH AREAS NORTH OF MEXICO BAY COULD APPROACH SCA LATE
IN THE AFTERNOON.

AS THE STORM SYSTEM MOVES EAST OF THE AREA TONIGHT...WINDS AND WAVES
WILL BUILD SO HAVE RAISE SMALL CRAFT ADVISORIES ALONG THE LAKE
ONTARIO NEARSHORES LATE TONIGHT THROUGH SATURDAY MORNING.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 10 AM EST
     FRIDAY FOR NYZ004>008.
     WINTER WEATHER ADVISORY UNTIL 10 AM EST FRIDAY FOR NYZ012-019-
     020-085.
MARINE...SMALL CRAFT ADVISORY FROM 1 AM FRIDAY TO 7 AM EST SATURDAY FOR
         LOZ042>045.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...SMITH/THOMAS
SHORT TERM...APFFEL
LONG TERM...APFFEL/HITCHCOCK
AVIATION...THOMAS
MARINE...SMITH







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