Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 260027
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
827 PM EDT MON APR 25 2016

.SYNOPSIS...
A STALLED FRONTAL BOUNDARY WILL BEGIN TO SAG SOUTHWARD OVERNIGHT
AS A LOW MOVES SOUTHEASTWARD WHILE REMAINING SOUTH OF NEW YORK.
SOUTH OF THE FRONT...SHOWERS AND POSSIBLE THUNDERSTORMS WILL
ACCOMPANY THE LOW...MAINLY LATE TONIGHT. MEANWHILE EAST OF LAKE
ONTARIO AND WELL NORTH OF THE FRONT...OVERNIGHT TEMPERATURES WILL
BE LOW ENOUGH FOR A MIX OF RAIN AND SNOW...BUT WITH LITTLE OR NO
ACCUMULATION. A COOL RAW DAY WILL FOLLOW ON TUESDAY UNDER A
NORTHERLY FLOW. HIGH PRESSURE WILL RETURN ON WEDNESDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
AN IMPRESSIVE BAROCLINIC BOUNDARY WILL CONTINUE TO STRENGTHEN ACROSS
THE LOWER GREAT LAKES THIS EVENING BEFORE A WEAKENING LOW MOVES FROM
WISCONSIN ESE INTO THE OHIO VALLEY AND THEN INTO PENNSYLVANIA BY
TUESDAY MORNING. DRY WEATHER SHOULD CONTINUE FOR SEVERAL MORE HOURS
INTO THE EVENING BEFORE PRECIPITATION BEGINS TO DEVELOP ALONG THE
BOUNDARY LATE THIS EVENING AS A SERIES OF UPPER LEVEL IMPULSES MOVE
OVERHEAD WITH STRENGTHENING FRONTOGENESIS IN THE LOWER LEVELS.

THE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS THE FORECAST AREA WILL
PRESENT A VARIETY OF CONDITIONS OVERNIGHT. ACROSS THE SAINT LAWRENCE
VALLEY AND HIGHER ELEVATIONS OF THE NORTH COUNTRY...ON THE NORTHERN
SIDE OF THE FRONTAL BOUNDARY...TEMPERATURES WILL FALL INTO THE MID
30S OVERNIGHT. SUBSEQUENTLY SOME AREAS MAY SEE SOME WET FLAKES
OVERNIGHT...HOWEVER TEMPERATURES SHOULD BE JUST WARM ENOUGH TO
PRECLUDE ANY ACCUMULATIONS. EVERYWHERE ELSE SHOULD SEE PRECIP
FALLING AS ALL RAIN THROUGH THE OVERNIGHT PERIOD. ELEVATED
INSTABILITY NEAR THE PA BORDER WILL BE JUST STRONG ENOUGH TO
SUPPORT A POTENTIAL FOR A FEW RUMBLES OF THUNDER OVERNIGHT. A
ELUDED TO ABOVE...WITH A FRONTAL BOUNDARY DRAPED DIRECTLY ACROSS
THE FORECAST AREA...OVERNIGHT LOWS WILL RANGE FROM THE LOW TO MID-
30S IN THE SAINT LAWRENCE VALLEY AND NORTH COUNTRY TO AROUND 50
NEAR THE PA BORDER.

IT WILL BE A WET START TO THE DAY ON TUESDAY AS THE MAIN PIECE OF
UPPER LEVEL ENERGY CURRENTLY OVER NORTHERN WISCONSIN WILL BE
APPROACHING WESTERN NEW YORK WHILE THE SURFACE LOW SLIDES BY TO OUR
SOUTH ACROSS PA. THIS SHOULD ALLOW SHOWERS TO PERSIST AT LEAST INTO
MID-MORNING BEFORE THE VORTMAX PASSES OVERHEAD AROUND MID-DAY. COLD
AIR WILL THEN BEGIN TO SURGE SOUTHWARDS INTO THE FORECAST AREA IN
THE WAKE OF THE VORTMAX. THE COOLER UPSLOPE FLOW COMBINED WITH
LINGERING MOISTURE MAY GENERATE AREAS OF LOW CLOUDS AND POSSIBLY
EVEN SOME PATCHY DRIZZLE SOUTH OF LAKE ONTARIO AND ACROSS THE
NIAGARA FRONTIER IN THE AFTERNOON BEFORE DRIER CANADIAN AIR BEGINS
TO FILTER IN LATE IN THE DAY...BRINGING SOME CLEARING BY DAY`S END.

UNDER THE NORTHERLY FLOW AND COLD ADVECTIVE REGIME TOGETHER WITH
ABUNDANT LOW LEVEL MOISTURE...EXPECT TEMPERATURES TO STRUGGLE TO
REACH THE MID 40S FOR MUCH OF THE REGION. EARLY MORNING TEMPERATURES
ALONG THE SOUTHERN TIER WILL INITIALLY CLIMB INTO THE MID 60S EARLY
IN THE DAY...HOWEVER TEMPERATURES WILL FALL DURING THE DAY INTO THE
UPPER 40S TO LOWER 50S BY THE END OF THE DAY.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/...
RAIN ASSOCIATED WITH THE FRONTAL WAVE WILL BE SOUTH OF THE AREA BY
EARLY TUESDAY EVENING. LINGERING CLOUDS IN MOIST UPSLOPE FLOW DURING
THE EVENING WILL CLEAR OVERNIGHT AS A MUCH DRIER AIRMASS ADVECTS
INTO THE LOWER LAKES AS HIGH PRESSURE BUILDS INTO NORTHWEST ONTARIO
AND THE UPPER LAKES. IT WILL BE ANOTHER CHILLY NIGHT WITH LOWS IN
THE LOWER 30S ON THE LAKE PLAINS AND UPPER 20S ACROSS THE INTERIOR
SOUTHERN TIER. THE NORTH COUNTRY WILL DROP INTO THE LOWER TO MID 20S
WITH NO OFF-LAKE INFLUENCE AND EARLIER CLEARING.

ON WEDNESDAY SURFACE HIGH PRESSURE WILL EXPAND EASTWARD INTO THE
LOWER LAKES AND NEW ENGLAND. THIS WILL BRING A RETURN TO SUNSHINE
ACROSS THE ENTIRE REGION. DESPITE THE SUNSHINE...THE AIRMASS WILL
REMAIN CHILLY WITH NORTH TO NORTHEAST FLOW AND COLD ADVECTION. THIS
WILL KEEP HIGHS IN THE LOWER 50S IN MOST AREAS...WITH MID TO UPPER
40S ACROSS THE NORTH COUNTRY AND ALONG THE SOUTH SHORE OF LAKE
ONTARIO. HIGH PRESSURE REMAINS OVER THE NORTHERN LAKES AND NEW
ENGLAND WEDNESDAY NIGHT AS THE NEXT SYSTEM MOVES INTO THE OHIO
VALLEY.

MODEL GUIDANCE BEGINS TO DIVERGE BY THURSDAY WITH THE HANDLING OF
THE NEXT SYSTEM MOVING INTO THE OHIO VALLEY. THE GFS AND CANADIAN
GLOBAL REMAIN FARTHER NORTH AND EAST AND MORE AGGRESSIVE IN MOVING
RAIN INTO WESTERN NY...WHILE THE NAM AND 00Z ECMWF ARE SLOWER AND
FARTHER SOUTH. GIVEN THE MODEL DIFFERENCES...HAVE KEPT A BROAD
GRADIENT IN POPS FOR THURSDAY WITH LIKELY ACROSS THE WESTERN
SOUTHERN TIER BY AFTERNOON AND CHANCES EXTENDING AS FAR NORTH AS
BUFFALO AND ROCHESTER BY THE END OF THE DAY.

THE MODEL DIFFERENCES GROW MORE APPARENT FOR THURSDAY NIGHT AND
FRIDAY AS THE GFS BRINGS THE OHIO VALLEY SYSTEM MUCH FARTHER NORTH
AND EAST WITH RAIN OVERSPREADING THE ENTIRE REGION. THE 00Z ECMWF
KEEPS THIS SYSTEM FARTHER SOUTH AND WEAKER...WHILE THE 12Z CANADIAN
GLOBAL GEM IS SOMEWHAT OF A COMPROMISE SOLUTION. AGAIN GIVEN THE
MODEL UNCERTAINTIES...HAVE OFFERED A BROAD GRADIENT OF POPS WITH
LIKELY ACROSS THE SOUTHERN TIER THURSDAY NIGHT AND A CHANCE TO THE
SOUTH SHORE OF LAKE ONTARIO...WITH CHANCE POPS IN A SIMILAR LOCATION
FOR FRIDAY.

TEMPERATURES WILL REMAIN ON THE COOL SIDE THURSDAY THROUGH FRIDAY
WITH HIGHS GENERALLY IN THE MID TO UPPER 50S. IF THE WETTER GFS
SOLUTION WERE TO VERIFY...TEMPERATURES WOULD REMAIN EVEN COOLER.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
THE FORECAST FOR THE WEEKEND INTO THE START OF NEXT WEEK REMAINS A
BIT UP IN THE AIR. AT FIRST GLANCE... THE GLOBAL MODELS ARENT IN
TERRIBLE AGREEMENT WITH THE LARGE SCALE PATTERN... WITH LOW-
AMPLITUDE RIDGING UP THE EAST COAST... TROUGHING INTO NEW ENGLAND
KEEPING A FEED OF COOLER CANADIAN SOURCED AIR INTO REGION. A LARGE
SCALE TROUGH WILL ALSO BE IN PLACE ACROSS THE CENTRAL CONUS... WHICH
WILL SLOWLY PUSH TOWARD THE FORECAST AREA BY SUNDAY INTO MONDAY PER
THE EC / OR EJECT SHORTWAVES TOWARD THE EAST COAST PER THE GFS. WITH
REGARD TO TEMPERATURES... EXPECT NEAR TO SLIGHTLY BELOW NORMAL
TEMPERATURES WITH THE FEED OF COOLER CANADIAN AIR INTO THE REGION
FOR THE WEEKEND. SATURDAY HAS THE BEST CHANCE OF BEING DRY BEFORE
INCREASING CHANCES FOR SHOWERS SUNDAY INTO EARLY MONDAY... WHICH
WILL LARGELY DEPEND ON HOW THE CENTRAL CONUS TROUGHING EJECTS
EASTWARD.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
VFR FLIGHT CONDITIONS WILL CONTINUE THIS AFTERNOON AND EVENING WITH
A DEVELOPING BOUNDARY FORMING FROM NW TO SE ACROSS THE WESTERN
PORTION OF NY. EXPECT SOME SPRINKLES TO THE NORTH OF THIS BOUNDARY.
SHOWERS ALONG THE BOUNDARY WILL BLOSSOM TONIGHT WITH STABLE RAIN AND
EVEN SOME SNOW MIXING IN ACROSS PARTS OF THE NORTH COUNTRY AND SAINT
LAWRENCE VALLEY. MEANWHILE...ISOLATED CONVECTION WILL BE POSSIBLE
ACROSS THE SOUTHERN TIER...HOWEVER CONFIDENCE REMAINS LOW ENOUGH
TO NOT WARRANT INCLUSION IN THE KJHW TAF.

THERE WILL BE A FAIRLY STRONG INVERSION ACROSS THE STATE AS WELL BUT
LESSENING AND LOST TOGETHER IN THE FAR SOUTH WHERE CONVECTIVE
POTENTIAL WILL BE THE HIGHEST. WITH THIS SCENARIO...EXPECT SOME MVFR
CONDITIONS TO DEVELOP...WITH OCCASIONALLY IFR CONDITIONS
POSSIBLE...MAINLY NORTH OF THE BOUNDARY. A PERIOD OF IFR CONDITIONS
IS EXPECTED ON TUESDAY IN THE MOIST NORTHERLY FLOW AS THE FRONT SAGS
TO THE SOUTH. EXPECT A SLOW RETURN TO VFR CONDITIONS TOWARD THE
AFTERNOON AS DRIER AIR FILTERS IN ACROSS THE REGION FROM CANADA.

OUTLOOK...
TUESDAY NIGHT AND WEDNESDAY...VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
FRIDAY AND SATURDAY...VFR.

&&

.MARINE...
A FRONTAL BOUNDARY OVER THE STATE WILL SAG SOUTH OVERNIGHT AS A
SURFACE LOW MOVES ESE INTO PA. NORTHEAST WINDS WILL INCREASE
NORTH OF THIS FRONTAL BOUNDARY...ESPECIALLY ON LAKE ONTARIO WHERE
SMALL CRAFT ADVISORIES WILL BE IN PLACE...FIRST ACROSS THE WESTERN
END OF THE LAKE...AND AS THE DAY AND NIGHT PROGRESS...THE CENTRAL
AND SOUTHEASTERN PORTIONS OF THE LAKE. WINDS WILL BE LESS IN
STRENGTH OVER LAKE ERIE...AND WITH GREATEST WAVE HEIGHTS TOWARDS
THE WESTERN END OF THE LAKE.

THIS FRONTAL BOUNDARY WILL SLIP FURTHER SOUTH TUESDAY WITH HIGH
PRESSURE AGAIN PUSHING SOUTHWARD ACROSS THE REGION WITH ANOTHER
PERIOD OF LIGHT WINDS AND WAVES ON THE LAKES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR LOZ042-043.
         SMALL CRAFT ADVISORY FROM 7 AM TO 8 PM EDT TUESDAY FOR
         LOZ044.

&&

$$

SYNOPSIS...ZAFF
NEAR TERM...WOOD
SHORT TERM...HITCHCOCK
LONG TERM...CHURCH
AVIATION...WOOD
MARINE...ZAFF



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