Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 211238
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
738 AM EST FRI NOV 21 2014

.SYNOPSIS...
LAKE EFFECT SNOWS WILL WEAKEN LATER THIS AFTERNOON AS HIGH PRESSURE
PASSES BY TO THE SOUTH OF OUR NEW YORK. MUCH WARMER AIR WILL ARRIVE
OVER THE WEEKEND AND INTO EARLY NEXT WEEK ALONG WITH RAIN SHOWERS AT
TIMES...POTENTIALLY BRINGING A FLOOD RISK TO AREAS WHICH WERE BURIED
BY LAKE EFFECT SNOW. TEMPERATURES WILL THEN TURN COLDER AGAIN FOR
THE SECOND HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE SURFACE PATTERN AT 12Z THIS MORNING SHOWS BROAD HIGH PRESSURE
CENTERED OVER THE MIDWEST STATES EXPANDING ACROSS THE GREAT LAKES
REGION. A SURFACE TROUGH HAS SHIFTED ACROSS THE WESTERN AND
CENTRAL NEW YORK WHICH HAS VEERED WINDS TO THE NORTHWEST. THIS
FLOW HAS ACTED TO TRANSITION SINGLE BAND LAKE EFFECT TO A MULTI-
BANDED PATTERN. 850MB TEMPS OF -15C ARE CONTINUING TO PROVIDE WELL
BELOW NORMAL SURFACE TEMPERATURES AND EXTREME LAKE INDUCED
INSTABILITY WHICH WILL CONTINUE TO SUPPORT THE LAKE EFFECT THROUGH
TODAY.

OFF LAKE ERIE...THE LATEST KBUF AND CANADIAN MOSAIC RADAR SCANS ARE
SHOWING MULTIPLE BANDS OF NORTHWEST TO SOUTHEAST LAKE EFFECT ACROSS
WESTERN NEW YORK WITH UPSTREAM MOISTURE CONNECTIONS TO LAKE HURON
AND GEORGIAN BAY. HAVE UPDATED THE FORECAST TO INCLUDE MORE COVERAGE
OF CHANCE POPS FOR LIGHT SNOW SHOWERS. THE NARROW AND SCATTERED
NATURE OF THE BANDS SHOULD NOT BRING ADDITIONAL SIGNIFICANT
ACCUMULATIONS. WILL CONTINUE THE LAKE EFFECT HEADLINES ACROSS THE
SOUTHERN TIER WITH THE ADDED ENHANCEMENT OF UPSLOPE FLOW INTO THE
HIGHER TERRAIN ALLOWING FOR A BIT MORE ACCUMULATION IN THAT REGION.
2 TO 4 ADDITIONAL INCHES ARE POSSIBLE HERE WITH ONLY ABOUT AN INCH OR
TWO ACROSS THE REMAINDER OF THE AREA. LATER TODAY WINDS ARE EXPECTED
TO BACK WHICH MAY SHIFT THESE MULTIPLE BANDS TO A WEST-EAST PATTERN
BEFORE A SUBSIDENCE INVERSION FROM THE SURFACE HIGH SQUASHED THE
LAKE BANDS GOING INTO THIS AFTERNOON.

OFF LAKE ONTARIO...NORTHWEST FLOW IS ALSO TRANSITIONING LAKE EFFECT
HERE TO MULTI-BANDS ALONG THE SOUTHEASTERN LAKE SHORE FROM ROCHESTER
TO FAIR HAVEN. LAKE EFFECT SHOULD HOLD HERE THROUGH THE MORNING WITH
3-6 INCH ACCUMULATIONS IN THE LAKE EFFECT ADVISORY AREAS. THE OSWEGO
COUNTY WARNING WILL CONTINUE AS THE LAKE SNOWS WILL SHIFT BACK
NORTH WITH BACKING WINDS LATER TODAY. THIS MAY BRING AN ADDITIONAL
FEW INCHES DEPENDING ON HOW LONG THE BANDS REMAIN ORGANIZED FOR.
LAKE INDUCED EQUILIBRIUM LEVELS 10-15 KFT WILL LOWER BELOW 5KFT
OVERNIGHT WHICH WILL BRING AN END TO LAKE EFFECT OVERNIGHT
DISSIPATING NEAR WATERTOWN.

OUTSIDE OF THE LAKE EFFECT EXPECT PARTLY SUNNY SKIES TODAY WITH SOME
INCREASE IN CLOUD COVER TONIGHT AS WARM ADVECTION DEVELOPS ALOFT.
HIGH TEMPS WILL ONLY RISE INTO THE LOW TO MID 20S TODAY THEN FALLING
BACK INTO THE TEENS TONIGHT WITH WIND CHILLS DROPPING INTO THE
SINGLE DIGITS WITH A STEADY SOUTHWEST FLOW.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
THE FOCUS FOR THIS PERIOD REMAINS THE POTENTIAL FOR SIGNIFICANT
WIDESPREAD FLOODING...AS MUCH WARMER TEMPERATURES AND RAINFALL PUSH
INTO THE REGION.

THE WATER STORED IN THE RECENTLY FALLEN LAKE EFFECT SNOW IS LIKELY
TO BE AT LEAST SEVERAL INCHES. AT THIS TIME...IT APPEARS THAT THE
GREATEST CONCERN FOR FLOODING WILL BE IN THE SUNDAY NIGHT THROUGH
TUESDAY TIME FRAME. SUNDAY NIGHT WILL REMAIN MILD WITH LOWS
REMAINING WELL ABOVE FREEZING. BY MONDAY...SURFACE TEMPERATURES WILL
BE CLIMBING TOWARDS 60 DEGREES WHICH WITH DEWPOINTS IN THE MID TO
UPPER 40S AND SOUTHERLY WINDS SHOULD ALLOW FOR MUCH IF NOT ALL OF
THE SNOWPACK TO MELT.

THE HIGH LIQUID IN THE SNOWPACK COMBINED THE FALLING RAINFALL WILL
LIKELY LEAD TO FLOODING...BOTH URBAN AND AREAL AS WELL AS
SIGNIFICANT RISES ON LOCAL STREAM/CREEKS AND RIVERS. IT IS DIFFICULT
TO SAY AT THIS POINT HOW SIGNIFICANT THE FLOODING WILL BE WITH THE
EXACT AMOUNT OF WATER STORED IN THE SNOWPACK STILL AN UNKNOWN. ONCE
THIS IS ANSWERED...A BETTER IDEA OF THE SEVERITY OF THE FLOODING
WILL BE BETTER KNOWN.

HIGH PRESSURE WILL BE CENTERED OVER THE CAROLINAS SATURDAY MORNING.
THE RETURN FLOW AROUND THE HIGH WILL BE ADVECTIING THE LEADING EDGE
OF A WARMER AIRMASS INTO THE REGION ON AN INCREASING SOUTHWESTERLY
FLOW AS 850 MB TEMPERATURES GO ABOVE FREEZING. INITIALLY THIS COULD
BE PROBLEMATIC WITH THE LOW LEVEL ARCTIC AIRMASS STILL ENTRENCHED
ACROSS THE REGION WITH A STRONG INVERSION LIKELY IN PLACE SATURDAY
MORNING. AS THE SHORTWAVE OVER THE INTERMOUNTAIN WEST EJECTS OUT
OVER THE GREAT LAKES...ISENTROPIC ASCENT AND A SHOT OF PV ADVECTION
SATURDAY WILL SUPPORT A PERIOD OF RAIN DEVELOPING FROM WEST TO EAST.
LATEST PROFILES WOULD SUGGEST THIS FALLS AS MAINLY LIGHT RAIN.
HOWEVER...THERE COULD STILL BE SOME POCKETS OF BELOW FREEZING
TEMPERATURES AT THE SURFACE WHICH MAY PRODUCE SOME PATCHY FREEZING
RAIN AT THE ONSET...ESPECIALLY ACROSS THE HILLS SOUTH OF BUFFALO AND
ROCHESTER...AND ALSO VALLEYS TO THE EAST OF LAKE ONTARIO. SHARP
WARMING ALOFT WILL LIMIT MAINTENANCE FOR SUB-ZERO WET BULBING SO
THINK ANY ICING THREAT WILL BE LIMITED...BUT WILL STILL NEED TO BE
MONITORED.

THE WARMING TREND WILL BEGIN SATURDAY WITH DAYTIME HIGHS IN THE MID
TO UPPER 30S OR MUCH OF THE AREA WITH TEMPERATURES NEAR 40 ALONG THE
LAKE ERIE SHORE AND NIAGARA FRONTIER. ALTHOUGH THIS WILL CAUSE SOME
MELTING OF THE DEEP SNOWPACK IN PLACE EAST OF THE LAKE ERIE...
FLOODING CONCERNS AT THIS TIME LOOK MINIMAL AS THE SNOWPACK WILL
ABSORB THIS MELT.

WEAK ISENTROPIC ASCENT WILL THEN BE ONGOING THROUGH THE DAY SATURDAY
NIGHT INTO EARLY SUNDAY...AS A 100 KNOT JET DEVELOPS OVERHEAD IN
RESPONSE TO THE DEEPENING LONGWAVE TROUGH UPSTREAM. THIS WILL HELP
ORIENT A MID-LEVEL BAROCLINIC ZONE ACROSS THE AREA WHICH WILL SERVE
AS A FOCUS FOR ONGOING LIGHT PRECIPITATION DURING THIS PERIOD.

TEMPERATURE RECOVERY WILL CONTINUE SATURDAY NIGHT WITH AN INCREASING
SOUTHERLY LOW LEVEL FLOW AND WARM AIR ADVECTION LIKELY KEEPING
OVERNIGHT TEMPERATURES ABOVE FREEZING. DEWPOINT TEMPERATURES LOOK TO
ALSO GO ABOVE FREEZING. THIS COMBINED WITH ADDITIONAL RAIN...ALBEIT
LIGHT WILL LEAD TO FURTHER RIPENING OF THE DEEP SNOW PACK.

THIS LIFT WILL EXIT THE REGION LATE SUNDAY AS RIDGING DEVELOPS
NORTHWARD INTO THE REGION. THIS WILL END THE THREAT OF PRECIPITATION
FOR A SHORT TIME...ALTHOUGH LINGERING LOW LEVEL MOISTURE MAY KEEP
CLOUD COVER IN PLACE. DEEP LAYER SOUTHERLY FLOW WILL CONTINUE TO
ADVECT WARMER AIR INTO THE REGION. AFTERNOON TEMPERATURES NEARING 50
DEGREES WITH DEWPOINTS CONTINUING TO RISE INTO THE MID TO UPPER 30S.
THE COMBINATION OF WARMING TEMPERATURES...INCREASE SOUTHERLY WINDS
AND RISING DEWPOINTS SHOULD ALLOW FOR THE DEEP SNOWPACK EAST OF BOTH
GREAT LAKES TO CONTINUE TO COMPACT AND DIMINISH IN HEIGHT.

SHORTWAVE EJECTS NORTHEAST FROM THE CENTRAL APPALACHIANS SUNDAY
LIFTING ACROSS THE AREA SUNDAY NIGHT. THE MAIN BRUNT OF DYNAMICS...
MOISTURE AND RAIN WILL QUICKLY SPREADS ACROSS THE REGION SUNDAY
EVENING. DIFFLUENCE ALOFT AND THE LIFTING SHORTWAVE WILL PROVIDE
DYNAMIC FORCING FOR ASCENT OVER THE REGION. ISENTROPIC ASCENT
COMMENCES AS THE WARM FRONT LIFTS INTO THE REGION SUNDAY NIGHT.
PER LATEST GEFS...PRECIPITABLE WATER VALUES FORECAST +2 TO +3
STANDARD DEVIATION AS VALUES INCREASE TO NEAR 1.25 INCHES. PROFILES
INDICATE A DEEPLY SATURATED COLUMN WHICH DOES GIVE AT LEAST SOME
POTENTIAL FOR LOCALLY HEAVY RAIN. HOWEVER..IT DOES APPEAR THAT THIS
WILL BE A RATHER QUICK SHOT OF PRECIPITATION WITH MOST OF THE RAIN
OUT OF THE AREA BY MONDAY MORNING...AS A DRY SLOT PUNCHES INTO THE
REGION IN WAKE OF THE WARM FRONT. WILL MAINTAIN RAINFALL AMOUNTS
DURING THIS PERIOD IN THE ONE QUARTER TO ONE THIRD OF AN INCH RANGE.

THE BASE OF THE UPPER LEVEL TROUGH AND ITS COLD AIR WILL REMAIN JUST
TO OUR WEST THROUGH THE COURSE OF MONDAY NIGHT. THIS WILL ALLOW FOR
SURFACE TEMPERATURES TO REMAIN ABOVE FREEZING THROUGH THE NIGHT AND
ALLOW FOR SNOWPACK MELTING TO CONTINUE. WITH THE TROUGH NEARBY WILL
CARRY A LOW CHANCE POP FOR A PASSING SHOWER.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
FOR THE TUESDAY THROUGH THURSDAY TIME PERIOD COOLING TEMPERATURES
WILL END THE THREAT OF FLOODING...BUT AGAIN RENEW THE LAKE EFFECT
SNOW POTENTIAL.

ON TUESDAY AN AMPLIFIED UPPER AIR PATTERN WILL CONTINUE AS A LONG
WAVE TROUGH WILL BE FOUND OVER THE GREAT LAKES REGION AND DOWN
TOWARDS THE SOUTHERN MISSISSIPPI VALLEY. THIS TROUGH WILL SPLIT THE
RIDGE TO OUR EAST (PRIOR WARM AIRMASS) AND RIDGE ACROSS THE WEST.

WITH SHORTWAVES PASSING THROUGH THIS UPPER LEVEL TROUGH...AND WITH
THIS TROUGH NOW NEARING OUR REGION WILL MAINTAIN LOW CHANCE POPS FOR
A MIX OF RAIN AND SNOW. AS THE COLD AIR DEEPENS THROUGH THE
DAY...LAKE EFFECT SNOW WILL AGAIN BECOME A CONCERN.

BY TUESDAY NIGHT TEMPERATURES ALOFT AT 850 HPA WILL HAVE DROPPED TO
NEAR -10C...AND FALLING. ALOFT THIS UPPER LEVEL LOW TO OUR WEST WILL
NOT BE AS DEEP AS THIS CURRENT WEEK OF LAKE EFFECT SNOW...COLD AIR
NOT AS DEEP AND CAPPING INVERSION HEIGHTS NOT AS TALL. THAT SAID
PARAMETERS ARE STILL LOOKING FAVORABLE FOR ANOTHER BAND OF LAKE
EFFECT SNOW STARTING TUESDAY PM ACROSS AREAS NORTHEAST OF THE
LAKES...THEN DROPPING SOUTHWARD THROUGH TUESDAY NIGHT AND WEDNESDAY.
WITH THE COLD AIR NOT AS DEEP THERE MAY EVEN BE A LITTLE RAIN MIXED
IN WITH THE BANDS OF SNOW DURING THE DAY WEDNESDAY.

A SHORTWAVE WILL CROSS THE EASTERN GREAT LAKES WEDNESDAY/WEDNESDAY
NIGHT...WHICH MAY DISRUPT THE BANDS SOME...BEFORE A WESTERLY WIND
CARRIES THE LAKE EFFECT SNOW INLAND TO AREAS EAST OF THE LAKES...AND
SOUTH OF BUFFALO/WATERTOWN FOR WEDNESDAY NIGHT.

BANDS OF LAKE EFFECT SNOW WILL FADE EARLY THURSDAY AS WE GET A
LITTLE WARM AIR ADVECTION ALOFT AHEAD OF AN APPROACHING SHORTWAVE.
THIS SHORTWAVE MAY BRING SOME LIGHT GENERAL SNOW TO WNY BY LATE IN
THE DAY THURSDAY.

&&

.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
NORTHWEST FLOW HAS DEVELOPED ACROSS THE REGION BEHIND A SURFACE
TROUGH. THIS HAS CAUSED THE LAKE EFFECT TO TAKE ON A MULTI-BAND
PATTERN OFF OF BOTH LAKES ERIE AND ONTARIO. FORECASTING THESE NARROW
SHIFTING BANDS IS VERY DIFFICULT SO HAVE GENERALLY KEEP VFR IN THE
TAFS WITH A TEMPO FOR IFR IN PASSING LAKE BANDS.

WINDS WILL BACK THIS AFTERNOON/EVENING TO SOUTHWEST FLOW WHICH WILL
SHIFT LAKE BANDS NORTH AND BRING RAPID WEAKENING AS SURFACE RIDGING
BUILDING OVER NEW YORK LOWERS INVERSION HEIGHTS. SOME CLOUDS WILL
INCREASE OVERNIGHT BUT REMAIN VFR AS WARM ADVECTION BEGINS ALOFT.

OUTLOOK...
SATURDAY...VFR.
SATURDAY NIGHT THROUGH MONDAY...PERIODS OF IFR/MVFR IN RAIN. LLWS
POSSIBLE SUNDAY NIGHT AND INTO MONDAY MORNING.
TUESDAY...MAINLY VFR WITH A CHANCE OF RAIN/SNOW SHOWERS.

&&

.MARINE...
SMALL CRAFT ADVISORIES IN PLACE FOR THE NEARSHORE WATERS. HIGH
PRESSURE WILL BUILD ACROSS THE GREAT LAKES REGION TODAY AND WEAKEN
THE INFLUENCING SFC PRESSURE GRADIENT. WINDS WILL FIRST RELAX
THROUGH TODAY BUT WAVES LOOK TO REMAIN ELEVATED INTO THE EVENING
WHERE ADVISORIES THEN EXPIRE.

ANOTHER STORM SYSTEM WILL LIFT NORTH OUT OF THE LOWER MISSISSIPPI
RIVER VALLEY SUNDAY TO MICHIGAN BY SUNDAY NIGHT. THIS DEEPENING
STORM SYSTEM WILL BRING SOME ELEVATED WINDS WITH POSSIBLE GALES ON
LAKE ERIE AND ADVISORIES POSSIBLE ON LAKE ONTARIO BY MONDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 6 PM EST THIS EVENING FOR
     NYZ006.
     LAKE EFFECT SNOW ADVISORY UNTIL 6 PM EST THIS EVENING FOR
     NYZ004-005.
     FLOOD WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY MORNING
     FOR NYZ010>012-085.
     LAKE EFFECT SNOW WARNING UNTIL NOON EST TODAY FOR NYZ019-020.
     LAKE EFFECT SNOW ADVISORY UNTIL NOON EST TODAY FOR NYZ021.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR
         LOZ042.

&&

$$

SYNOPSIS...SMITH
NEAR TERM...SMITH
SHORT TERM...TMA
LONG TERM...THOMAS
AVIATION...SMITH
MARINE...SMITH






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