000
FXUS61 KBUF 192350
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
750 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/...
KBUF RADAR SHOWS THE SHOWER/THUNDERSTORM ACTIVITY ACROSS INLAND 
WESTERN NY HAS DISSIPATED THIS EVENING WITH THE LOSS OF DAYTIME 
HEATING. SHOWERS ACTIVITY ACROSS NORTHERN NY IS ALSO SHIFTING 
EASTWARD WHICH WILL LEAVE OUR FORECAST AREA WITH A WARM AND 
RAIN-FREE OVERNIGHT. SATELLITE STILL SHOWS OVERCAST SKIES ASSOCIATED 
WITH COLD AIR DAMMING CONDITIONS ACROSS CENTRAL AND EASTERN NY INTO 
NEW ENGLAND. FOR WESTERN NY WE HAVE MORE IN THE WAY OF CLEARER SKIES 
THANKS TO A SOUTHERLY DOWNSLOPE FLOW.  

OVERNIGHT INTO MONDAY MORNING...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. TEMPERATURES 
WILL REMAIN MILD OVERNIGHT NOT FALLING BELOW THE MID TO UPPER 50S 
WITH 60 OR SO FOUND IN URBAN AREAS DUE TO MOIST AIRMASS IN PLACE. 

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 WEDNESDAY 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 /THURSDAY 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 /00Z MONDAY THROUGH FRIDAY/...
TONIGHT VFR WILL CONTINUE EARLY ON FROM THE GENESEE VALLEY WESTWARD 
WHILE TO THE EAST A COLD AIR DAMMING PATTERN WILL KEEP OVERCAST LOW 
CLOUDS IN PLACE. SOME MVFR OR EVEN IFR STRATUS MAY DEVELOP ACROSS 
NORTH CENTRAL PA AND SNEAK INTO THE HIGHER TERRAIN OF THE SOUTHERN 
TIER OVERNIGHT ON PERSISTENT SSE FLOW. 

OTHERWISE LATER TONIGHT...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/SMITH
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...HITCHCOCK/SMITH
MARINE...HITCHCOCK