Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 061138
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
738 AM EDT WED MAY 6 2015

.SYNOPSIS...
A WEAK WAVE OF LOW PRESSURE SLIDING ALONG A STALLED OUT FRONT OVER
NORTHERN PENNSYLVANIA WILL BRING SHOWERS TO THE EXTREME SOUTHERN
EDGE OF WESTERN NEW YORK EARLY THIS MORNING. SHOWER ACTIVITY SHOULD
RETREAT FROM SOUTHERN TIER BY LATE IN THE DAY. FOLLOWING THE PASSAGE
OF THIS WAVE...THE REMAINDER OF THE WORK WEEK WILL FEATURE A RETURN
TO DRY WEATHER AND ABOVE NORMAL TEMPERATURES...BEFORE THE NEXT
CHANCE FOR PRECIPITATION ARRIVES THIS WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
A WEAK WAVE OF LOW PRESSURE WILL MOVE WEST TO EAST ALONG A STALLED
AND DIFFUSE FRONT ACROSS PENNSYLANIA. THESE SHOWERS WILL LAST INTO
THE LATE MORNING THEN MOVE OUT OF THE FORECAST AREA DURING THE EARLY
AFTERNOON. DRIER AIR WILL BUILD SOUTHWARD ACROSS THE REGION WITH
CLEARING SKIES RETURNING TO MUCH OF THE FORECAST AREA BY MID
AFTERNOON. CLOUDS MAY LINGER TIL LATE IN THE DAY ALONG THE NY/PA
LINE. HIGH TEMPERATURES TODAY WILL RISE TO THE UPPER 60S TO LOWER
70S FOR MUCH OF THE AREA EXPERIENCING MOSTLY SUNNY CONDITIONS...WITH
MIDDLE 60S FOR THE WESTERN SOUTHERN TIER WHERE SUNNIER SKIES WILL
WAIT TIL LATER IN THE DAY.

THE CLEARING TREND WILL CONTINUE INTO THE EVENING AND NIGHT WITH
MAINLY CLEAR SKIES ACROSS THE REGION...ALTHOUGH WITH THE CLEARING
SKIES AND LIGHT WINDS THERE WILL LIKELY BE AREAS OF FOG FORMING IN
THE VALLEYS AND LAKE BASINS OF THE SOUTHERN TIER TO CENTRAL NY
DURING THE OVERNIGHT TO EARLY MORNING HOURS. FOG IS ALSO LIKELY
ALONG THE LAKE ERIE SHORE AND INTO THE DOWNTOWN BUFFALO AREA EARLY
THURSDAY MORNING. OVERNIGHT LOWS WILL FALL BACK TO THE UPPER 40S TO
LOWER 50S...VERY CLOSE TO THE DEWPOINTS...THUS POSSIBILITY OF THE
FOGGIER CONDITIONS.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
ON THURSDAY AN UPPER LEVEL RIDGE WILL BUILD EASTWARD INTO THE OHIO
VALLEY AND LOWER LAKES. SURFACE HIGH PRESSURE WILL DRIFT OFF THE
EAST COAST AND ALLOW DEEP SOUTHWEST RETURN FLOW TO DEVELOP ACROSS
THE REGION...SETTING THE STAGE FOR AN EXTENDED PERIOD OF MID SUMMER
WARMTH. THE GFS AND NAM CONTINUE TO SHOW A WEAK QPF SIGNAL DURING
THE AFTERNOON FROM THE SOUTHERN TIER INTO THE FINGER LAKES...
INDICATIVE OF THE MODEL TRYING TO DEVELOP SOME CONVECTION. THIS DOES
NOT SEEM PLAUSIBLE GIVEN THE BUILDING MID LEVEL HEIGHTS AND
DEVELOPING CAPPING...AND OVERALL LACK OF INSTABILITY AND SOURCE OF
LOW LEVEL CONVERGENCE. WITH THIS IN MIND...HAVE CONTINUED WITH A DRY
FORECAST ACROSS THE ENTIRE CWA.

MODEL POINT SOUNDINGS SUGGEST THERE WILL BE A LAYER OF LOW STRATUS
DURING THE MORNING ACROSS THE HIGHER TERRAIN FROM THE SOUTHERN TIER
INTO THE FINGER LAKES...AND THIS WILL BREAK AND EVOLVE INTO A
DIURNAL CUMULUS FIELD WITH DAYTIME HEATING. ELSEWHERE DEVELOPING
STABLE LAKE SHADOWS WILL KEEP A GREATER AMOUNT OF SUNSHINE ON THE
LAKE PLAINS. 850MB TEMPS RISE TO AROUND +12C...SUPPORTING HIGHS IN
THE UPPER 70S TO AROUND 80 AWAY FROM THE LAKES. THE LIGHT SYNOPTIC
SCALE BACKGROUND FLOW AND STRONG DIFFERENTIAL HEATING WILL SUPPORT
THE DEVELOPMENT OF LAKE BREEZE CIRCULATIONS...WHICH WILL KEEP ALL
THE LAKESHORES COOLER WITH ONSHORE WINDS DURING THE AFTERNOON.

BY FRIDAY THE DEEP SOUTHWEST FLOW INCREASES...WITH 850MB TEMPS
SOARING TO AROUND +14C. THE WARMER AIRMASS AND WARMER START TO THE
DAY WILL ALLOW TEMPERATURES TO REACH THE MID 80S AWAY FROM THE
LAKES. SURFACE DEWPOINTS WILL BEGIN TO INCREASE BY FRIDAY MAKING FOR
A MORE HUMID FEEL TO GO ALONG WITH THE HEAT. LOCAL LAKE BREEZES
SHOULD AGAIN FORM BY AFTERNOON WITH COOLER TEMPS ALONG ALL THE
LAKESHORES. SIMILAR TO THURSDAY...MODEL GUIDANCE TRIES TO DEVELOP
ISOLATED CONVECTION ALONG AND INLAND FROM LAKE BREEZE BOUNDARIES
DURING THE AFTERNOON. WITH A LACK OF ANY SYNOPTIC SCALE SUPPORT AND
VERY WARM/CAPPED MID LEVELS...THIS TOO APPEARS SPURIOUS. WITH THIS
IN MIND...HAVE AGAIN GONE WITH A DRY FORECAST FOR FRIDAY.

MAINLY DRY WEATHER WILL CONTINUE INTO FRIDAY NIGHT. TEMPERATURES
WILL ONLY DROP INTO THE LOWER TO MID 60S ON THE LAKE PLAINS AND
UPPER 50S IN THE COOLEST VALLEYS AND TUG HILL REGION. THESE
OVERNIGHT LOW TEMPERATURES ARE NEAR WHERE OUR HIGH TEMPERATURE
SHOULD BE FOR EARLY MAY.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
MID SUMMER WARMTH WILL LIKELY CONTINUE THROUGH MUCH OF THE LONG TERM
PERIOD. THE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL STEADILY
INCREASE WITH EACH PASSING DAY AS DEEPER MOISTURE AND AN INCREASING
NUMBER OF WEAK SHORTWAVES CROSS THE REGION.

LOOKING AT THE DETAILS...EXPECT ANOTHER VERY WARM DAY SATURDAY WITH
850MB TEMPS AROUND +14C SUPPORTING MID 80S AWAY FROM THE LAKESHORES.
HUMIDITY WILL CONTINUE TO CREEP UPWARD...MAKING IT FEEL LIKE MID
SUMMER. THE GFS IS MORE AGGRESSIVE IN LEANING A WEAK FRONTAL ZONE
INTO THE LOWER LAKES BY AFTERNOON...WHILE THE ECMWF HOLDS THIS
SYSTEM FARTHER NORTH AND WEST. CONTINUE TO FAVOR THE SLOWER ECMWF
SOLUTION GIVEN THE STRENGTH OF THE EAST COAST RIDGE. WITH THIS IN
MIND HAVE CONTINUED WITH JUST A LOW CHANCE OF AN AFTERNOON SHOWER OR
THUNDERSTORM.

SUNDAY THROUGH TUESDAY THE PATTERN WILL BECOME MORE ACTIVE AS A DEEP
TROUGH DEVELOPS OVER THE ROCKIES AND MOVES SLOWLY EAST ACROSS THE
PLAINS. A FRONTAL ZONE WILL STALL OVER THE GREAT LAKES REGION...
WHILE NUMEROUS CONVECTIVELY GENERATED MID LEVEL VORTICITY MAXIMA
MOVE EAST ACROSS THE OHIO VALLEY AND GREAT LAKES. THESE SYSTEMS WILL
BE DIFFICULT TO PLACE IN TIME AND SPACE...BUT WILL SUPPORT PERIODS
OF ENHANCED LARGE SCALE ASCENT AND GREATER SHOWER/THUNDERSTORM
CHANCES.

THE GFS TRIES TO DROP THE FRONTAL ZONE JUST SOUTH OF OUR AREA FOR
MONDAY AND TUESDAY...WHILE THE ECMWF HOLDS THE BOUNDARY JUST NORTH
OF LAKE ONTARIO KEEPING OUR REGION IN THE VERY WARM AND HUMID AIR.
AGAIN FAVOR THE ECMWF SCENARIO WITH THE WARMTH HOLDING THROUGH
MONDAY.

BY TUESDAY BOTH THE GFS AND ECMWF SWEEP THE CENTRAL PLAINS TROUGH
INTO THE WESTERN LAKES...WITH A COLD FRONT MOVING EAST ACROSS THE
OHIO VALLEY AND LOWER GREAT LAKES. THIS WILL SUPPORT A CHANCE OF A
FEW MORE SHOWERS AND THUNDERSTORMS...AND ALSO HERALD THE ARRIVAL OF
SOMEWHAT COOLER AIR.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
WILL HAVE LOWER MVFR TO IFR CONDITIONS ACROSS THE SOUTHERN TIER
EARLY THIS MORNING AS AREAS OF FOG AND STRATUS FORM IN THE RAIN
SATURATED AIR AND SHOWERS LINGER CLOSE TO THE NY/PA LINE. THE LOW
MVFR TO IFR CONDITIONS ACROSS THE SOUTHERN TIER IMPROVE ONLY A BIT
TO MVFR LATER TODAY OWING TO THE CLOSE PROXIMITY OF THE WEAK FRONTAL
BOUNDARY. OTHERWISE...EXPECT VFR CONDITIONS FOR THE REST OF WESTERN
AND CENTRAL NY AND ACROSS THE NORTH COUNTRY WHERE HIGH PRESSURE AND
DRIER AIR WILL BUILD IN FROM THE NORTHWEST.

OUTLOOK...
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...VFR.
FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS SOUTHEAST OF LAKE ERIE.
SATURDAY THROUGH MONDAY...MAINLY VFR...WITH A CHANCE OF SHOWERS/
THUNDERSTORMS AND ATTENDANT MVFR.

&&

.MARINE...
WITH A WEAK PRESSURE GRADIENT REMAINING IN PLACE ACROSS THE LOWER LAKES
REGION THROUGH THE END OF THE WORK WEEK...EXPECT RELATIVELY LIGHT WINDS
AND MINIMAL WAVES TO CONTINUE THROUGH FRIDAY.

&&

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

&&

$$

SYNOPSIS...WCH
NEAR TERM...WCH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...WCH
MARINE...JJR/WCH



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