Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 301730
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
130 PM EDT SAT APR 30 2016

.SYNOPSIS...
A WARM FRONT LIFTING OUT OF THE LOWER OHIO VALLEY WILL SPREAD
RAIN ACROSS THE FORECAST AREA TONIGHT INTO SUNDAY WITH A CHANCE
OF THUNDERSTORMS SUNDAY AFTERNOON AND EVENING AS AN AREA OF LOW
PRESSURE MOVES ACROSS THE LOWER GREAT LAKES. SHOWERS SHOULD TAPER
OFF MONDAY AS THE LOW MOVES AWAY FROM THE REGION. COOL AND
UNSETTLED WEATHER IS EXPECTED TO PREVAIL FOR MUCH OF THE COMING
WEEK AS A DEEP UPPER LEVEL TROUGH SETTLES OVER THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE CENTERED OVER THE WESTERN END OF HUDSON BAY WILL
EXTEND ACROSS THE LOWER GREAT LAKES AND THE NORTHEASTERN CORRIDOR.
UNFORTUNATELY A LAYER OF MOISTURE BEING ADVECTED IN FROM THE
ATLANTIC ON EASTERLY 850-925MB FLOW REMAINS TRAPPED UNDERNEATH THIS
HIGH AND IS ENCOMPASSING MUCH OF NEW YORK STATE AND PENNSYLVANIA.
WHILE THIS MOISTURE SHOULD GRADUALLY MIX OUT AS WE MOVE INTO THE
AFTERNOON HOURS...CLOUDS WILL LIKELY HANG AROUND FOR A GOOD PORTION
OF THE DAY ACROSS MUCH OF WESTERN AND NORTH-CENTRAL NEW YORK WITH
THE EXCEPTION OF THE NORTH COUNTRY...WHICH IS UNDER THE INFLUENCE OF
DRIER NORTHERLY FLOW OUT OF THE SAINT LAWRENCE VALLEY. SKIES THERE
SHOULD REMAIN MOSTLY SUNNY THROUGHOUT THE DAY.

THE WIDESPREAD CLOUD COVER WILL HAVE THE EFFECT OF DEPRESSING
TEMPERATURES AND HAVE GONE SEVERAL DEGREES BELOW GUIDANCE ACROSS
WESTERN NEW YORK WHERE HIGHS WILL LIMP INTO THE MID 50S. EAST OF
LAKE ONTARIO THE PLENTIFUL SUNSHINE SHOULD ALLOW TEMPERATURES TO
CLIMB INTO THE LOWER 60S.

EXPECT RAIN TO DEVELOP ACROSS THE FORECAST AREA TONIGHT AS A WARM
FRONT LIFTS OUT OF THE LOWER OHIO VALLEY. RAIN WILL SPREAD FROM FAR
SOUTHWESTERN NEW YORK THIS EVENING TO THE DOORSTEP OF THE NORTH
COUNTRY BY DAYBREAK SUNDAY. A GENEROUS AMOUNT OF LIFT AND SOLID
MOISTURE ADVECTION ON THE NOSE OF A 30KT LOW LEVEL JET SHOULD
PRODUCE A ZONE OF FAIRLY STEADY RAINFALL WITH AREAS OF HEAVIER
SHOWERS EMBEDDED THEREIN AS IT CROSSES THE AREA TONIGHT WITH MANY
AREAS FORECAST TO RECEIVE A QUARTER TO HALF INCH OF RAINFALL
OVERNIGHT. THE COMBINATION OF WARM ADVECTION AND PLENTY OF
CLOUDS/RAIN WILL LIMIT TEMPERATURE FALLS WITH OVERNIGHT TEMPERATURES
EXPECTED TO DIP INTO THE MID TO UPPER 40S.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
SEVERAL PERIODS OF RAIN CAN BE EXPECTED IN THE SUNDAY-MONDAY
TIMEFRAME ALONG WITH A CHANCE OF THUNDERSTORMS ON SUNDAY AFTERNOON.
THIS WILL ALL OCCUR AS A MID-LEVEL SHORTWAVE TROUGH AND SURFACE LOW
PRESSURE IS FORECAST BY 00Z MODELS TO TRACK FROM THE OHIO VALLEY ON
SUNDAY ACROSS NEW YORK STATE AND INTO NEW ENGLAND ON MONDAY. A
WIDESPREAD RAIN WILL BE WORKING ACROSS WESTERN AND CENTRAL NEW YORK
SUNDAY MORNING FORCED BY LOW/MID-LEVEL WARM ADVECTION. HAVE BUMP
POPS UP TO 100 PERCENT ALONG THIS EAST/NORTHEAST ADVANCING BOUNDARY.

BY SUNDAY AFTERNOON THE WARM SECTOR WILL BE SPREAD NORTH OVER AT
LEAST THE SOUTHERN HALF OF THE FORECAST AREA. DEWPOINTS WILL RISE
INTO THE 50S WITH SOME SUN INCREASING INSTABILITY ESPECIALLY TOWARD
THE NY/PA STATE LINE. HAVE INCLUDED LIKELY POPS FOR RAIN SHOWERS
WITH A CHANCE FOR THUNDERSTORMS SUNDAY AFTERNOON AS SYNOPTIC SCALE
INCREASES AHEAD OF THE APPROACHING AND OCCLUDING LOW. SURFACE HIGHS
ON SUNDAY AFTERNOON SHOULD REACH INTO THE 50S FOR MOST WITH SOME
LOCATIONS TOWARD THE PA LINE RUNNING NEAR OR ABOVE 60.

THE OCCLUDED UPPER LOW AND SHORTWAVE EMBEDDED VORT MAX WILL SHIFT
OVER NEW YORK SUNDAY NIGHT WITH ANOTHER LIKELY PERIOD OF
RAIN/SHOWERS. HAVE LEFT A CHANCE OF WRAP AROUND SHOWERS ON MONDAY
TAPERING OFF IN THE AFTERNOON AS THE LOW AND ASSOCIATED LOW LEVEL
JET EXITS INTO NEW ENGLAND. TEMPS SUNDAY NIGHT WILL HOLD IN THE 40S
WITH THE CLOUD COVER AND SHOWERS THEN WILL ONLY WARM INTO THE L/M
50S ON MONDAY IN COLD ADVECTION BEHIND THE LOW WHERE 850MB TEMPS
FALL TO AROUND 0C. RIDGING FROM EXPANSIVE HIGH PRESSURE CENTERED
OVER THE GREAT PLAINS WILL NOSE NORTH ACROSS THE GREAT LAKES FOR
MONDAY NIGHT AND TUESDAY PROVIDING FOR DRY WEATHER. TEMPS WILL PUSH
A LITTLE LOWER IN THE COOL AND DRY AIR MONDAY NIGHT THEN WARM
ADVECTION AHEAD OF A STORM SHIFTING INTO THE WESTERN GREAT LAKES
WILL HELP BOOST HIGHS TUESDAY INTO THE U50S/L60S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A COOLER PATTERN DEVELOPS FOR MID-LATE NEXT WEEK AS A TROUGH IS
FORECAST TO DEEPEN OVER THE EAST COAST. 00Z MODELS SHOW THIS TROUGH
WILL EVENTUALLY EVOLVE INTO A CLOSED LOW OVER THE MID ATLANTIC
STATES BY LATE WEEK. UNFORTUNATELY...THIS PATTERN IS NOT CONDUCIVE
FOR WARM WEATHER ACROSS THE GREAT LAKES REGION. H85 TEMPS FOR OUR
REGION WILL GENERALLY BE IN THE LOWER SINGLE DIGITS...AND THIS WILL
EQUATE TO TEMPERATURES THAT WILL AVERAGE NEAR OR JUST BELOW NORMAL
EARLY MAY VALUES.

IN TERMS OF PRECIPITATION...BOTH THE 00Z GFS AND 00Z ECMWF SHOW
SEVERAL WET PERIODS THROUGH THE LONG TERM FORECAST PERIOD. THIS
WILL ALL BE LED IN BY A COLD FRONT WEDNESDAY AFTERNOON AND NIGHT.
THE PASSAGE OF THIS FEATURE WILL PRODUCE SCATTERED SHOWERS OVER THE
REGION...THEN THE FRONT WILL BECOME ABSORBED WITHIN A COMPLEX
COASTAL STORM SYSTEM LATER THURSDAY AND FRIDAY WHICH MODELS SHOW
WILL STALL OR SLOWLY RETROGRADE WEST DUE TO A BLOCKED PATTERN OVER
THE NORTH ATLANTIC. TIMING AND MORE SPECIFIC LOCATION OF SHOWERS
THROUGH THIS PERIOD REMAINS UNCERTAIN AT THIS POINT SO BROAD BRUSH
CHANCE POPS WILL CONTINUE TO BE THE FLAVOR UNTIL MESO-MODELS CAN
LOCK ONTO MORE DETAIL.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A LAYER OF MOISTURE REMAINS TRAPPED UNDERNEATH AN AREA OF HIGH
PRESSURE CURRENTLY IN PLACE ACROSS THE REGION. THIS WILL RESULT IN
MAINLY MVFR CIGS ACROSS THE SOUTHERN TIER INTO THIS EVENING.
ELSEWHERE...VFR CONDITIONS WILL EXIST AT KIAG/KBUF/KROC AND KART
AS DRIER AIR FILTERS IN FROM THE NORTH.

MID/HIGH CLOUDS WILL INCREASE FROM WEST TO EAST FROM 22Z ONWARDS
AS A WARM FRONT APPROACHES THE REGION. ANY IMPROVEMENT ACROSS THE
SOUTHERN TIER WILL DETERIORATE TO IFR TOWARDS THE END OF THE
FORECAST PERIOD AS RAIN WORKS ITS WAY NORTH INTO THE AREA TONIGHT.

OUTLOOK...

SUNDAY...VFR/MVFR WITH RAIN LIKELY. IFR CONDITIONS LIKELY ACROSS THE
SOUTHERN TIER.
MONDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
TUESDAY...MAINLY VFR.
WEDNESDAY AND THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A BROAD AREA OF HIGH PRESSURE MOVING ACROSS THE REGION WILL
MAINTAIN TRANQUIL CONDITIONS ON THE LAKES INTO THIS EVENING.

A EAST-NORTHEASTERLY FLOW WILL FRESHEN TONIGHT AS A LOW PRESSURE
SYSTEM TRACKING OUT OF THE MISSISSIPPI VALLEY TRACKS TOWARDS THE
LOWER GREAT LAKES. AS THE EAST-NORTHEASTERLY WINDS STRENGTHENS TO
NEAR 20 KNOTS...WAVES WILL BUILD IN EXCESS OF 4 FEET ON THE WEST END
OF LAKE ONTARIO SUNDAY MORNING...HOWEVER THE WIND COMPONENT IS
CURRENTLY FORECASTED TO BE EASTERLY ENOUGH TO KEEP HIGHEST WAVES
IN CANADIAN WATERS AND WILL HOLD OFF ON SMALL CRAFT ADVISORIES FOR
NOW.

LOW PRESSURE WILL TRACK ACROSS LAKES ERIE AND ONTARIO SUNDAY
AFTERNOON THROUGH MONDAY MORNING. EASTERLY FLOW WILL SHIFT TO THE
SOUTHWEST BEHIND THE LOW AND THIS WILL LIKELY BRING A PERIOD OF
SMALL CRAFT ADVISORY LEVEL WINDS AND WAVES TO THE EAST END OF LAKE
ERIE SUNDAY NIGHT BEFORE WAVES DIMINISH MONDAY AS THE LOW PULLS AWAY
FROM THE REGION AND HIGH PRESSURE MOVES BACK ACROSS THE LAKES.

WESTERLY FLOW WILL MAINTAIN WAVES TO 4 FEET ON LAKE ONTARIO
THROUGH MONDAY BEFORE CONDITIONS ON THAT LAKE DIMINISH MONDAY
NIGHT. A GENERALLY WEAK PRESSURE GRADIENT WILL RESULT IN GENERALLY
TRANQUIL CONDITIONS ON THE LAKE TUESDAY THROUGH WEDNESDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA/WOOD
SHORT TERM...SMITH
LONG TERM...RSH/SMITH
AVIATION...TMA
MARINE...TMA/WOOD



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