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000
FXUS61 KBUF 081037
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
537 AM EST SUN DEC 8 2013

.SYNOPSIS...
LAKE EFFECT SNOWS EAST OF LAKE ONTARIO WILL TAPER OFF THIS MORNING
WHILE ELSEWHERE MID AND HIGH CLOUDS WILL INCREASE IN COVERAGE AHEAD
OF AN APPROACHING WARM FRONT. AS THE WARM FRONT CROSSES THE AREA
TONIGHT LOOK FOR LIGHT SNOW TO CHANGE OVER TO FREEZING DRIZZLE AND
EVENTUALLY TO DRIZZLE ON MONDAY. A COLD FRONT WILL MARCH ACROSS THE
REGION LATER ON MONDAY USHERING IN MUCH COLDER TEMPERATURES ALONG
WITH A POTENTIAL FOR LAKE EFFECT SNOWS THAT WILL REMAIN FOR MUCH OF
THE COMING WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
KTYX RADAR CONTINUES TO INDICATE LIGHT RETURNS OVER THE NORTH
COUNTRY AS COLD WESTERLY FLOW DOWN LAKE ONTARIO...AIDED BY UPSLOPE
FLOW ONTO THE TUG HILL PLATEAU CONTINUES TO GENERATE LIGHT SNOW
ACROSS THE AREA. A SUBSTANTIAL DRY SLOT ABOVE 850MB HAS BEEN HELPING
TO KEEP SNOWFALL RATES DOWN...GENERALLY IN THE NEIGHBORHOOD OF
0.25"/HOUR RADAR ESTIMATED...HOWEVER SNOW IS PERSISTENT ENOUGH TO
WARRANT LEAVING THE LAKE EFFECT SNOW ADVISORY FOR OSWEGO COUNTY IN
PLACE FOR NOW.

ELSEWHERE...MID AND HIGH CLOUDS WILL RAPIDLY THICKEN THIS MORNING IN
ADVANCE OF AN APPROACHING WARM FRONT. TEMPERATURES WILL GRADUALLY
WARM INTO THE UPPER 20S TODAY ACROSS MUCH OF THE FORECAST AREA WITH
THE EXCEPTION OF THE HIGHER ELEVATIONS OF THE SOUTHERN TIER AND NORTH
COUNTRY WHERE TEMPERATURES WILL REMAIN LOCKED IN THE MID 20S.

A VERY CHALLENGING FORECAST SCENARIO ARISES TONIGHT AS THE
AFOREMENTIONED WARM FRONT LIFTS NORTH ACROSS THE FORECAST AREA.
SUBSTANTIAL ISENTROPIC UPLIFT WILL BE FOUND ACROSS THE REGION WITH
ASCENT BEING MAXIMIZED ON THE NOSE OF A 30KT TO 40KT LOW LEVEL JET
THAT WILL BE CROSSING PENNSYLVANIA AND NEW YORK TONIGHT. THIS WILL
ALMOST CERTAINLY GENERATE WIDESPREAD PRECIPITATION ACROSS THE
REGION...HOWEVER AVAILABLE MOISTURE IS AN IMPORTANT CONSIDERATION
AND THE LAST SEVERAL MODEL RUNS HAVE BEEN CONSISTENT IN SHOWING THE
BULK OF THE DEEP MOISTURE REMAINING TO OUR EAST. IN ADDITION...THE
STRONGEST DYNAMICS WILL BE LOCATED WELL TO OUR NORTHWEST OVER
ONTARIO/QUEBEC...CLOSER TO THE TRACK OF A SURFACE LOW LIFTING OUT OF
THE UPPER GREAT LAKES. CONSIDERING THESE FACTS...A HIGH POP/LOW QPF
SCENARIO SEEMS MOST LIKELY.

PERHAPS THE MOST CHALLENGING ASPECT OF TONIGHT AND MONDAY`S FORECAST
IS PRECIP TYPE. STRONG WARM ADVECTION ALOFT WILL PUSH AN
ABOVE-FREEZING WARM NOSE NORTHWARDS TOWARDS WESTERN NEW YORK WITH
MODELS VARYING SOMEWHAT ON THE DEPTH/NORTHWARD EXTENT OF THIS WARM
NOSE WITH THE 00Z GFS BRINGING A DEEP WARM LAYER ACROSS MUCH OF THE
FORECAST AREA. THE 06Z NAM IS LEANING MUCH MORE STRONGLY TOWARDS
THIS SCENARIO AS OPPOSED TO THE 00Z RUN WHILE THE SREF MEMBERS MORE
OR LESS INDICATE AT LEAST A NOMINAL WARM LAYER ADVECTING ACROSS THE
AREA. THIS WOULD NORMALLY SUGGEST A STANDARD TRANSITION FROM SNOW
OVER TO SLEET/FREEZING RAIN GIVEN THE SUB-FREEZING SURFACE
LAYER...HOWEVER THAT PESKY LACK OF DEEP MOISTURE BECOMES A
SIGNIFICANT PROBLEM. MODEL SOUNDINGS ALMOST UNIVERSALLY INDICATE THE
DEVELOPMENT OF A SUBSTANTIAL DRY LAYER EXTENDING FROM 850MB CLEAR UP
TO 500MB...AS A SIGNIFICANT DRY SLOT CURRENTLY VISIBLE ON WV IMAGERY
OVER NW ARKANSAS ADVECTS NORTHEASTWARD. THIS WILL HAVE THE EFFECT OF
RAPIDLY DRYING OUT THE SNOW GROWTH LAYER...RESULTING IN AN IDEAL
SETUP FOR FREEZING DRIZZLE. THUS THE EXPECTED SCENARIO IS FOR A
BRIEF PERIOD OF LIGHT SNOW TO DEVELOP FROM SOUTH TO NORTH STARTING
THIS EVENING AS THE NOSE OF THE LOW LEVEL JET AND MAXIMUM ASCENT
PUSHES NORTH INTO WESTERN NEW YORK. EXPECT THIS TO QUICKLY CHANGE
OVER TO FREEZING DRIZZLE AS DRIER AIR ALOFT ADVECTS ACROSS THE
REGION. FREEZING DRIZZLE WILL LIKELY PERSIST THROUGH MUCH OF THE
NIGHT BEFORE THE SURFACE FINALLY WARMS ABOVE FREEZING ON
MONDAY...WITH ANY LINGERING PRECIPITATION CHANGING OVER TO JUST
DRIZZLE. GIVEN THE LACK OF DEEP MOISTURE...ICE ACCUMULATIONS SHOULD
NOT AMOUNT TO MORE THAN A TENTH OR SO...HOWEVER THERE IS ENOUGH
CONCERN ABOUT ICING ON ELEVATED SURFACES TO WARRANT THE ISSUANCE OF
A WINTER WEATHER ADVISORY FOR ALL OF THE FORECAST AREA FOR TONIGHT
INTO MONDAY.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A COMPLEX SURFACE WEATHER PATTERN WILL BE LIFTING NORTH ACROSS NEW
YORK THROUGH MONDAY WITH DOUBLE-BARRELED LOW PRESSURE CENTERS
LIFTING TO OUR WEST AND EAST. THE WESTERN LOW IS THE DEEPER PARENT
LOW WHICH WILL BE CENTERED NEAR LAKE SUPERIOR. A SURFACE TROUGH
AND WARM FRONT WILL STRETCH FROM THIS LOW ACROSS THE LOWER GREAT
LAKES REGION TO A SECONDARY LOW CENTER JUST OFF THE NEW JERSEY
COAST. ACROSS NEW YORK IN BETWEEN THE THE TWO LOWS MODELS SHOW
WARMER BUT DRIER AIR WORKING NORTH OVERRUNNING COLDER SUB-FREEZING
SURFACE TEMPS.

BOTH NAM AND GFS BUFKIT PLAN VIEWS SHOW THE IMPACT OF THE WARMER AIR
WILL BE TO RAISE THE HEIGHT OF THE PRIME DENDRITIC SNOW GROWTH ZONE
UP TO AROUND 15KFT WHILE THE DRIER AIR WILL STRIP STRIP AWAY MID
LEVEL MOISTURE LEVELING A SATURATED PROFILE BELOW 10KFT. THE
DISCONNECT OF THE SNOW GROWTH REGION AND BEST MOISTURE USUALLY LEADS
TO A DRIZZLE OR FREEZING DRIZZLE ENVIRONMENT. WITH SURFACE TEMPS
STILL BELOW FREEZING EARLY MONDAY HAVE WORDED THE FORECAST GRIDS
WITH FREEZING DRIZZLE INSTEAD OF SNOW THEN AS SURFACE TEMPS WARM
INTO THE UPPER 30S TO AROUND 40 THROUGH THE DAY EVENTUALLY SEE A
CHANGE OVER TO DRIZZLE ACROSS WESTERN AND NORTH CENTRAL NEW YORK
THROUGH THE DAY. THE LINGERING LOW LEVEL MOISTURE WILL KEEP OVERCAST
LOW CLOUDS THROUGH THE DAY.

COLDER AIR WILL WORK BACK ACROSS NEW YORK MONDAY NIGHT AS WINDS VEER
TO WESTERLY BEHIND THE DEPARTING STORM SYSTEM LIFTING ACROSS EASTERN
CANADA. 850MB TEMPERATURES WILL DROP TO BETWEEN -12C AND -15C
THROUGH THE NIGHT BUT THE WESTERLY FLOW ACROSS THE LAKES WILL HAVE
LIMITED SYNOPTIC MOISTURE TO WORK WITH. WILL CONTINUE WITH FOCUSING
LOWER CHANCES OF SNOW DOWNWIND OF THE LAKES WITH THE LIMITED
MOISTURE WITH MAYBE SOME SNOW FLURRIES ACROSS THE REMAINDER OF THE
FORECAST AREA. LOW TEMPERATURES WILL REACH INTO THE LOW 20S.

THROUGH TUESDAY A CONTINUED GENERALLY WESTERLY FLOW WILL CONTINUE
ACROSS NEW YORK WITH SYNOPTIC MOISTURE INCREASING AHEAD OF A SHORTWAVE
THAT IS FORECAST TO SHIFT ACROSS THE GREAT LAKES. FURTHER COOLING OF
850MB TEMPS LATER TUESDAY WILL LOWER THE SNOW GROWTH ZONE DOWN TO
AROUND 5KFT AND RAISE LAKE INVERSION HEIGHTS UP ABOVE 10KFT. THIS
COMBINATION WILL HELP LAKE EFFECT SNOW BANDS TO BECOME BETTER
ORGANIZED OVER THE LAKES THROUGH THE DAY WITH CHANCES OF LAKE EFFECT
SNOWS INCREASING EAST OF THE LAKES RIGHT THROUGH THE OVERNIGHT
PERIOD.

STILL A LITTLE TOO FAR OUT TO DETERMINE HOW MUCH SNOW CAN BE
EXPECTED AND FOR MORE EXACT LOCATIONS OF THE BANDS WHICH WILL LIKELY
PIVOT NORTH SOME AS THE SHORT WAVE APPROACHES. EVENTUALLY LAKE
EFFECT SNOW WATCHES MAY BE NEEDED DOWNWIND OF THE LAKES FOR A
SEVERAL DAY EVENT WHICH COULD RUN THROUGH LATE THURSDAY. OUTSIDE OF
THE LAKE EFFECT BANDS A BRISK WESTERLY FLOW WITH TEMPERATURES
LIMITED TO THE 20S WILL MAKE FOR A VERY CHILLY DAY. WIND CHILLS WILL
LINGER IN THE TEENS ALL DAY.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
IN THE EXTENDED PORTION OF THE FORECAST...THE CENTER OF THE DEEP
UPPER LEVEL TROUGH WILL ONLY SLOWLY DRIFT FROM HUDSON BAY INTO
NORTHERN QUEBEC WEDNESDAY AND THURSDAY...BEFORE EJECTING EASTWARD
INTO THE CANADIAN MARITIMES FRIDAY AND SATURDAY. THROUGH AT LEAST
THURSDAY...THIS FEATURE WILL MAINTAIN A BROAD CYCLONIC WESTERLY
FLOW OF COLD AIR ACROSS THE GREAT LAKES...WITH 850 MB TEMPS
FALLING TO AS LOW AS -18C/-20C BY THURSDAY. COUPLED WITH WHAT
SHOULD BE RICHER/DEEPER MOISTURE AND A HIGHER OVERALL CAPPING
INVERSION...THIS PATTERN WILL PRODUCE AN ENVIRONMENT FAVORABLE FOR
POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS TO THE EAST OF THE GREAT
LAKES...WITH THEIR EXACT PLACEMENT AND INTENSITY REMAINING
DEPENDENT ON SUBTLE SMALLER-SCALE SHORTWAVE FEATURES RIPPLING EAST
THROUGH THE LARGER SCALE UPPER TROUGH AND CAUSING SUBTLE
UNDULATIONS IN THE LOW-LEVEL FLOW.

BY THE LATTER PORTIONS OF THE PERIOD...THE MEDIUM RANGE GUIDANCE
SHOWS INCREASING DISCREPANCIES WITH BOTH THE TIMING AND AMPLITUDE OF
THE NEXT NOTEWORTHY SURFACE TROUGH...BEHIND WHICH A MORE NORTHERLY
FLOW OF COLDER AIR APPEARS POISED TO SPREAD ACROSS THE AREA AT THE
END OF THE WEEK. GIVEN THE RESULTANT INCREASE IN FORECAST
UNCERTAINTY...HAVE ELECTED TO TREND SNOW SHOWER CHANCES LOWER AND
INCREASINGLY MORE BROADBRUSH IN NATURE FOR THE LATTER PORTIONS OF
THE WEEK. ONE THING THAT APPEARS MORE CERTAIN IS TEMPS WILL REMAIN
BELOW AVERAGE...WITH DAYTIME HIGHS REMAINING LOCKED IN THE 20S
THROUGH THE END OF THE WEEK...AND NIGHTTIME LOWS GENERALLY IN THE
SINGLE DIGITS TO MID TEENS EACH NIGHT.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
FOR THE 06Z TAFS VFR FLIGHT CONDITIONS WILL PREVAIL...EXCEPT FOR
SOUTHEAST OF THE LAKES WHERE BANDS OF LIGHT LAKE EFFECT SNOW
CONTINUES WITH MVFR...AND EVEN IFR SOUTHEAST OF LAKE ONTARIO
CONTINUES. THESE BANDS OF SNOW WILL IMPACT THE KJHW TAF SITE
OVERNIGHT...AND LATER AS THE WINDS BACK SOME POSSIBLY NEAR THE KART
AIRFIELD TOMORROW. DRY AIR WILL CONTINUE TO WEAKEN THE LAKE BANDS
THROUGH THE NIGHT AND DAY TOMORROW EAST OF LAKE ONTARIO. THERE WILL
BE A BRIEF QUIET SPELL OF VFR AS WINDS BECOME LIGHT AND VARIABLE
BEFORE INCREASING IN STRENGTH FROM THE EAST.

WITH THE EASTERLY WINDS LOW CLOUDS WILL WANE...BUT MID AND HIGH
LEVEL CLOUDS WILL INCREASE THROUGH THE DAY. PRECIPITATION WILL REACH
THE SOUTHERN TIER EARLY SUNDAY EVENING FROM A STORM SYSTEM LIFTING
THROUGH THE MISSISSIPPI VALLEY AND INTO THE CENTRAL GREAT LAKES.
EXPECT PRECIPITATION TO REMAIN ALL SNOW THROUGH 06Z AS IT SPREADS
NORTHWARD TO TAF SITES SOUTH OF LAKE ONTARIO.

OUTLOOK...
SUNDAY NIGHT AND MONDAY...VFR/MVFR WITH SNOW AND RAIN LIKELY.
TUESDAY THROUGH THURSDAY...MAINLY VFR BUT IFR WITH LAKE EFFECT
SNOW EAST OF THE LAKES.

&&

.MARINE...
HIGH PRESSURE CROSSING THE LOWER GREAT LAKES TODAY WILL ALLOW FOR
WAVES TO BRIEFLY DIMINISH BEFORE SOUTHEASTERLY WINDS INCREASE
TONIGHT AS A WARM FRONT LIFTS ACROSS THE REGION. WINDS WILL VEER TO
THE SOUTHWEST MONDAY AND FRESHEN AS A COLD FRONT CROSSES THE LAKES.
A FRESH ROUND OF SMALL CRAFT ADVISORIES WILL BE LIKELY MONDAY IN THE
WAKE OF THE FRONT. EXPECT BRISK WEST NORTHWESTERLY FLOW TO PERSIST
AT LEAST INTO THE MIDDLE OF THE WEEK AS THE PRESSURE GRADIENT WILL
REMAIN TIGHT BETWEEN HIGH PRESSURE ENCOMPASSING MUCH OF THE CENTRAL
AND SOUTHERN UNITED STATES AND LOW PRESSURE CENTERED OVER HUDSON
BAY. HIGH PRESSURE NOSING ACROSS THE LAKES MAY BRING A BRIEF RESPITE
TO THE WINDS/WAVES ON THURSDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 2 PM EST
     MONDAY FOR NYZ006>008.
     LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     NYZ006.
     WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 11 AM EST
     MONDAY FOR NYZ001>005-010>014-085.
     WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST
     MONDAY FOR NYZ019>021.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR
         LOZ043>045.

&&

$$

SYNOPSIS...WOOD
NEAR TERM...WOOD
SHORT TERM...SMITH
LONG TERM...JJR
AVIATION...THOMAS
MARINE...WOOD