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000
FXUS61 KBUF 191953
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
353 PM EDT SUN MAY 19 2013

.SYNOPSIS...
A SOUTHWEST FLOW OF WARM AND MORE HUMID AIR WILL CONTINUE TO MOVE
INTO THE REGION THROUGH THE FIRST HALF OF THE WEEK. A FRONTAL
BOUNDARY WILL ALSO STALL NEARBY...SETTING THE STAGE FOR INCREASING
CHANCES FOR SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS. THE
UNSETTLED WEATHER WILL CONTINUE MUCH OF THE WEEK BEFORE A STRONG
COLD FRONT CROSSES THE AREA THURSDAY NIGHT WITH COOLER AND DRIER AIR
ARRIVING FRIDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
RADAR IMAGERY THIS AFTERNOON SHOWING AN AREA OF SHOWERS BLOSSOMING
OVER FAR EASTERN ONTARIO. THESE SHOWERS ARE BEING SUPPORTED MAINLY
BY PERSISTENT WARM ADVECTION AND ISENTROPIC UPGLIDE ALONG A SLOWLY
RETREATING WARM FRONTAL ZONE. THESE SHOWERS WILL CROSS THE SAINT
LAWRENCE RIVER THROUGH LATE AFTERNOON AND LIKELY CLIP PORTIONS OF
NORTHERN JEFFERSON AND LEWIS COUNTIES BEFORE TAPERING OFF DURING THE
EVENING. ELSEWHERE VISIBLE SATELLITE IMAGERY SHOWING A GOOD AMOUNT
OF SUNSHINE FROM THE NIAGARA FRONTIER EAST ACROSS ROCHESTER AND INTO
PORTIONS OF THE FINGER LAKES. A GOOD AMOUNT OF DIURNAL CUMULUS HAS
DEVELOPED ACROSS THE HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER...
AND THIS WILL PERSIST UNTIL EARLY EVENING BEFORE THE LOSS OF DAYTIME
HEATING.

OVERNIGHT INTO MONDAY MORNING A MID LEVEL RIDGE WILL NOSE NORTH INTO
MICHIGAN AND THE LOWER LAKES...WHILE NORTHWEST FLOW IS MAINTAINED
FROM THE SAINT LAWRENCE VALLEY INTO NEW ENGLAND. A FEW WEAK
SHORTWAVES WILL CONTINUE TO TRAVERSE THE NORTHWEST FLOW ALOFT...AND
THIS COMBINED WITH PERSISTENT WEAK WARM ADVECTION AND MOISTURE
CONVERGENCE ALONG A STALLED FRONTAL BOUNDARY MAY TOUCH OFF A FEW
MORE SHOWERS ACROSS THE NORTH COUNTRY. AMOUNTS SHOULD BE OF LITTLE
CONSEQUENCE HOWEVER...AND THE VAST MAJORITY OF THE TIME WILL BE RAIN
FREE. ELSEWHERE FROM OSWEGO COUNTY WESTWARD EXPECT A DRY NIGHT WITH
AT LEAST PARTLY CLEAR SKIES AFTER DIURNAL CUMULUS DISSIPATE THIS
EVENING. THE ONE EXCEPTION MAY BE ACROSS THE HIGHER TERRAIN OF THE
SOUTHERN TIER WHERE PERSISTENT SSE FLOW MAY BRING ANOTHER ROUND OF
LOW STRATUS IN LATE TONIGHT.

THE INCREASING LOW LEVEL MOISTURE COMBINED WITH NOCTURNAL COOLING
MAY ALLOW AT LEAST PATCHY LIGHT FOG/BR TO DEVELOP IN MANY AREAS
OVERNIGHT...WITH THE BEST CHANCE OF MORE WIDESPREAD FOG IN THE
TYPICAL SOUTHERN TIER VALLEYS. ANY FOG THAT DOES FORM WILL BURN OFF
BY MID MORNING MONDAY.

ON MONDAY THE WEAK/DIFFUSE FRONTAL BOUNDARY WILL REMAIN STALLED
ACROSS NORTHERN NY. THIS MAY PROVIDE ENOUGH FOCUS FOR A FEW MORE
SCATTERED SHOWERS AT TIMES IN THAT AREA. IN ADDITION...INSTABILITY
WILL BE GREATER ON MONDAY THAN RECENT DAYS AS LOW LEVEL MOISTURE
CONTINUES TO IMPROVE. NAM/GFS BOTH DEVELOP AROUND 1000J/KG OF CAPE
BY AFTERNOON INLAND FROM THE LAKES. THIS IS LIKELY OVERDONE DUE TO
THE PERSISTENTLY OVER-ESTIMATED SURFACE DEWPOINTS SEEN IN MODELS
LATELY...BUT STILL MAY DEVELOP ENOUGH INSTABILITY TO POP A FEW
WIDELY SCATTERED SHOWERS AND STORMS IN THE AFTERNOON. THE MOST
LIKELY AREAS FOR THIS WOULD BE FROM THE INTERIOR SOUTHERN TIER INTO
THE FINGER LAKES AND CENTRAL NY. ONSHORE FLOW ALONG ALL THE
LAKESHORES WILL KEEP STABLE LAKE SHADOWS APPARENT...WITH MORE
SUNSHINE AND MUCH LOWER CONVECTIVE RISK FOR THE AFTERNOON WITHIN
10-20 MILES OF THE LAKESHORES.

SOUTHWEST FLOW ALOFT AND BUILDING HEIGHTS WILL BOOST 850MB TEMPS TO
AROUND +15C IN THE WEST BY AFTERNOON...SUPPORTING HIGHS IN THE LOWER
80S. THE NORTH COUNTRY WILL BE A LITTLE COOLER WITH MORE PERSISTENT
CLOUD COVER...EXPECT MID 70S THERE. AS IS TYPICALLY THE CASE IN
MAY...ONSHORE FLOW WILL KEEP THE LAKESHORES MUCH COOLER.

&&

.SHORT TERM /MONDAY NIGHT THROUGH THURSDAY NIGHT/...
MONDAY NIGHT ANY DAYTIME CONVECTION TOWARDS THE EAST WILL QUICKLY
END WITH THE LOSS OF DAYTIME HEATING. THE UPPER LEVEL RIDGE WILL
BEGIN TO WEAKEN AS SLIGHT SHORTWAVES CREST THE TOP OF THE
RIDGE...AND THESE IMPULSES WILL MAINTAIN THE CHANCE FOR AN
OVERNIGHT SHOWER OR THUNDERSTORM.

BOTH TUESDAY AND WEDNESDAY WILL BE WARM AND HUMID AS SOUTHERLY WINDS
SOUTH OF THIS WEAK WARM FRONT CONTINUE TO ADVECT MOISTURE NORTHWARD
ACROSS THE EASTERN GREAT LAKES. DEWPOINTS BOTH DAYS ARE EXPECTED TO
RISE INTO THE LOW TO MID 60S...AND WITH 850 HPA TEMPERATURES BETWEEN
14 AND 17C AFTERNOON HIGHS WILL BE IN THE 70S...LOWER 70S ACROSS THE
NORTH COUNTRY AND MID TO UPPER 70S SOUTH OF LAKE ONTARIO. WEDNESDAY
MAY BE A FEW DEGREES COOLER DUE TO BUILDING MID LEVEL MOISTURE
DECREASING THE AMOUNT OF SUNSHINE.

THIS DAYTIME HEAT COMBINED WITH THE INCREASING MOISTURE WILL BRING
AN UNSTABLE ENVIRONMENT WITH LI`S DROPPING INTO THE -4 TO -7C RANGE.
SBCAPE VALUES BOTH DAYS WILL CLIMB INTO THE 1000 TO 1500 J/KG RANGE
WHICH WILL SUPPORT AN ENVIRONMENT FOR THUNDERSTORMS BOTH TUESDAY AND
WEDNESDAY. THE MID LEVEL LAPSE RATES GENERALLY HOLD IN THE 6 TO 7
C/KM RANGE WHICH ARE NOT TOO IMPRESSIVE AND WITH NO STRONG WIND
FIELDS WILL HOLD THE WORDING TO JUST GENERAL THUNDERSTORMS FOR NOW.
ONE CONCERN WILL BE TUESDAY WHEN THE WIND FIELD IS LIGHT...LESS THAN
25 KNOTS THROUGH 10-12K FEET. THIS LIGHT WIND FIELD MAY ALLOW FOR ANY
THUNDERSTORMS TO BE SLOW MOVING.

BY THURSDAY A SURFACE WAVE RIDING ALONG A FRONTAL BOUNDARY WILL
CROSS THE REGION DRAGGING A COLD FRONT THROUGH THE CWA. THIS AGAIN
WILL TRIGGER SHOWERS AND THUNDERSTORMS...WITH THE FRONT AND FALLING
MID LEVEL HEIGHTS PROVIDING THE LIFT AS INSTABILITY WILL BE MUCH
WEAKER. 850 HPA TEMPERATURES WILL BE A BIT COOLER WHICH WILL ALLOW
FOR COOLER TEMPERATURES IN THE 60S. FALLING DEWPOINTS WILL BRING AN
END TO THE BRIEF HUMID STRETCH.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
THIS TIME PERIOD WILL BE COOLER AND MORE SETTLED THAN PRIOR DAYS
AS AN UPPER LEVEL TROUGH WITH DRIER AIR SETTLES SOUTHWARD. THE 12Z
ECMWF IS DEEPER AND MORE PROGRESSIVE WITH THE TROUGH THAN THE
CORRESPONDING 12Z GFS...AND THE 00Z GEFS ENSEMBLE MEMBERS.

FOR FRIDAY...WILL HAVE A LOW CHANCE FOR A SHOWER EARLY IN THE DAY
TOWARDS THE EAST. OTHERWISE WILL KEEP THE REMAINDER OF FRIDAY AND
INTO SATURDAY DRY AS HIGH PRESSURE FROM THE NORTHERN GREAT LAKES
PUSHES TOWARDS THE EASTERN GREAT LAKES REGION. EXCEPTION WILL BE
ACROSS THE NORTH COUNTRY WHERE IF THE ECMWF SOLUTION WITH THE DEEPER
TROUGH WERE TO VERIFY ADDITIONAL CLOUD COVER AND INSTABILITY SHOWERS
UNDER THE COLD POOL WILL FALL SATURDAY.

DRY WEATHER WILL CONTINUE ON SUNDAY WITH BUILDING HEIGHTS ACROSS
THE GREAT LAKES REGION. A RETURN OF WARMER AIR AT 850 HPA WILL BRING
A RETURN OF MID 60S TO LOWER 70S ACROSS THE REGION.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
SCATTERED LIGHT SHOWERS EAST OF LAKE ONTARIO WILL END BY MID
AFTERNOON WITH ASSOCIATED MVFR CIGS IMPROVING TO VFR FROM WEST TO
EAST. ELSEWHERE SOME AREAS OF MVFR CIGS ACROSS THE HIGHER TERRAIN OF
THE WESTERN SOUTHERN TIER AND FINGER LAKES WILL SLOWLY IMPROVE TO
VFR THIS AFTERNOON.

TONIGHT MOST OF THE LOWER CLOUD DECKS SHOULD ERODE AWAY...ALTHOUGH
SOME MVFR OR EVEN IFR STRATUS MAY RE-DEVELOP ACROSS NORTH CENTRAL PA
AND SNEAK INTO THE HIGHER TERRAIN OF THE SOUTHERN TIER OVERNIGHT ON
PERSISTENT SSE FLOW. THE INCREASING LOW LEVEL MOISTURE MAY ALLOW FOR
SOME FOG DEVELOPMENT OVERNIGHT...WITH VSBY DROPPING TO AT LEAST MVFR
IN MANY LOCATIONS WITH IFR MORE PREVALENT ACROSS THE SOUTHERN TIER
VALLEYS.

ON MONDAY ANY FOG WILL BURN OFF BY MID MORNING...LEAVING MAINLY VFR
FOR THE REST OF THE DAY ACROSS LOWER ELEVATIONS...WITH SOME MVFR
CIGS STILL POSSIBLE IN A FEW SPOTS ACROSS HIGHER TERRAIN. A FEW
SCATTERED SHOWERS MAY CROSS THE NORTH COUNTRY IN THE MORNING AS A
WEAK BACKDOOR COLD FRONT BRUSHES ACROSS NORTHERN NY. ADDITIONAL
SCATTERED SHOWERS AND EVEN A FEW THUNDERSTORMS MAY DEVELOP IN THE
AFTERNOON ACROSS THE REST OF THE AREA...MAINLY INLAND FROM THE
STABLE LAKE SHADOWS. EXPECT COVERAGE TO REMAIN RATHER SPARSE IN MOST
AREAS...AND MOST IF NOT ALL OF THE TAF SITES SHOULD REMAIN BEHIND
THE LAKE BREEZE BOUNDARIES AND IN STABLE AIR.

OUTLOOK...
TUESDAY THROUGH THURSDAY...SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS WITH ASSOCIATED BRIEF MVFR/IFR...OTHERWISE VFR.
FRIDAY...VFR.

&&

.MARINE...
QUIET CONDITIONS WILL REMAIN IN PLACE ACROSS THE LOWER LAKES THROUGH
MUCH OF THE UPCOMING WEEK. WIND DIRECTIONS WILL BE VARIABLE DUE TO
AFTERNOON LAKE BREEZES...AND ALSO A STALLED OUT FRONTAL BOUNDARY
WHICH WILL BE NEARBY MUCH OF THE WEEK. THUNDERSTORM CHANCES WILL
INCREASE TUESDAY THROUGH THURSDAY...AND SOME STORMS MAY PRODUCE
BRIEF PERIODS OF LOCALLY HIGHER WINDS AND WAVES.

&&

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

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...HITCHCOCK
MARINE...HITCHCOCK