Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 301844
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
244 PM EDT SAT AUG 30 2014

.SYNOPSIS...
HIGH PRESSURE WILL DRIFT OFF THE NEW ENGLAND COAST AND PROVIDE
ANOTHER MAINLY DRY DAY WITH JUST A SMALL CHANCE FOR SHOWERS THIS
AFTERNOON ACROSS WESTERN NEW YORK. A TROUGH OF LOW PRESSURE WILL
THEN CROSS THE REGION TONIGHT INTO SUNDAY WITH A BETTER CHANCE OF
SHOWERS AND SCATTERED THUNDERSTORMS. MONDAY WILL BE DRY THE VAST
MAJORITY OF THE TIME...ALTHOUGH A FEW WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE WITH A WARM AND HUMID AIRMASS STILL IN
PLACE.

&&

.NEAR TERM /THROUGH TONIGHT/...
A FEW SHOWERS WHICH DEVELOPED ALONG A WARM FRONT HAVE DISSIPATED
EARLY THIS AFTERNOON...WITH JUST SOME CLOUDS REMAINING ALONG THE
SUBTLE BOUNDARY. MOIST AIR HAS BEGUN TO BUILD BEHIND THE
FRONT...WITH DEW POINTS RISING INTO THE UPPER 60S WEST OF
ROCHESTER. THIS WILL INCREASE INSTABILITY THIS AFTERNOON...BUT
WITH LITTLE TO FOCUS THIS...ANY SHOWERS OR THUNDERSTORMS SHOULD BE
QUITE SPARSE IN COVERAGE. MOST HIGH RESOLUTION GUIDANCE KEYS ON A
SUBTLE WAVE WHICH WILL CROSS FROM W-E LATE THIS AFTERNOON AND
POSSIBLY TAKE ADVANTAGE OF SURFACE CONVERGENCE EAST OF LAKE ERIE.
THIS SAID...THE VAST MAJORITY OF THE REGION SHOULD BE DRY
TODAY...WITH SUMMER-LIKE TEMPERATURES IN 80S...WITH UPPER 80S IN
DOWNSLOPE REGIONS NORTH OF I-90.

EXPECT THERE WILL BE A BRIEF PERIOD OF SUBSIDENCE BEHIND THE
EXITING SHORTWAVE WHICH SHOULD KEEP THE REGION MOSTLY DRY THIS EVENING.
THIS IS IN AGREEMENT WITH MOST SHORT RANGE MODEL GUIDANCE...BUT
SOME RUNS OF THE NAM/RGEM FORECAST ANOTHER LINE OF SHOWERS THIS
EVENING WHICH APPEARS LESS LIKELY TO DEVELOP GIVEN THE EXITING DISTURBANCE.
STEADIER SHOWERS SHOULD MOVE IN WITH THE NOSE OF A 30-40 KT 850MB
FLOW...WHICH COINCIDES WITH AN INCREASE IN SURFACE MOISTURE. THE
REGION WILL ALSO BE IN THE RIGHT REAR JET QUADRANT...AND WITH
AMPLE MOISTURE WITH PWAT VALUES NEAR 1.8 INCHES. THIS
SAID...CONVECTION WILL PROBABLY BE SPOTTY...WITH CLUSTERS OF
SHOWERS...SO WILL STAY WITH LIKELY POPS. THERE IS ENOUGH
INSTABILITY IN NAM/GFS FORECAST PROFILES TO SUPPORT SCATTERED
THUNDERSTORMS AS WELL. A FEW OF THE STRONGER STORMS MAY PRODUCE
LOCALLY HEAVY DOWNPOURS GIVEN THE HIGH PWAT ENVIRONMENT AND
TALL/SKINNY CAPE PROFILES. UNFAVORABLE TIME OF DAY...LIMITED
INSTABILITY AND MARGINAL SHEAR PROFILES SHOULD PREVENT CONVECTION
FROM BECOMING TOO STRONG.

A WARM/MUGGY AIRMASS COMBINED WITH INCREASING CLOUDS AND A SSW
BREEZE WILL KEEP TEMPERATURES VERY MILD OVERNIGHT...WITH LOWS IN THE
LOWER 70S ON THE LAKE PLAINS OF WESTERN NY AND MID TO UPPER 60S
ELSEWHERE.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
BEST CHANCES FOR PRECIPITATION DURING THIS PERIOD WILL BE ON
SUNDAY...WITH CHANCES LESSENING FROM WEST TO EAST AS THE DAY
PROGRESSES. THEN EXPECT PLENTY OF USABLE DRY TIME FROM SUNDAY NIGHT
INTO MONDAY NIGHT WITH JUST SOME DIURNALLY DRIVEN SHOWERS/ISOLATED
THUNDERSTORMS MONDAY MAINLY ALONG AND INLAND OF ANY LAKE
BREEZES...WITH THE BEST CHANCES ACROSS THE SOUTHERN TIER.

THE SURFACE LOW WILL WEAKEN AND ELONGATE AS IT CROSSES SOUTHERN
ONTARIO ON SUNDAY. ACTUAL BOUNDARY ASSOCIATED WITH THIS SYSTEM LOOKS
AS THOUGH IT WILL NEVER ACTUALLY MAKE IT INTO NEW YORK
STATE...BECOMING NEARLY STATIONARY ACROSS SOUTHERN QUEBEC AS THE
AFOREMENTIONED SURFACE LOW RIDES EAST ALONG IT. HOWEVER A WEAK
SURFACE TROUGH OUT AHEAD OF THIS BOUNDARY WILL PUSH THROUGH THE
FORECAST AREA BY EARLY AFTERNOON...HELPING TO ENHANCE
SHOWER/THUNDERSTORM CHANCES ESPECIALLY DURING THE FIRST HALF OF THE
DAY. PWATS WILL RUN BETWEEN 1.75"-2" AHEAD OF THE SURFACE
BOUNDARY...THEN DROP OFF QUITE A BIT BEHIND THE TROUGH WITH PWATS
LOWERING DOWN TO AROUND 1.25" DURING THE AFTERNOON. MAIN SHORTWAVE
ENERGY AND BEST FORCING ALOFT WILL ALSO REMAIN NORTH OF NEW YORK
STATE. SO EVEN THOUGH PLENTY OF MOISTURE WILL BE IN PLACE DURING THE
FIRST HALF OF THE DAY...THE COMBINATION OF THE SURFACE TROUGH
PASSING THROUGH THE FORECAST AREA BY EARLY AFTERNOON PRIOR TO PEAK
HEATING AND THE LACK OF GOOD UPPER LEVEL SUPPORT...AM NOT EXPECTING
ANY WIDESPREAD HEAVY RAIN PRODUCING THUNDERSTORMS...ALTHOUGH A FEW
ISOLATED HEAVY DOWNPOURS CANNOT BE RULED OUT. IN FACT...IT LOOKS AS
THOUGH A LAKE SHADOW MAY FORM OVER THE NIAGARA FRONTIER NORTHEAST OF
LAKE ERIE DURING THE AFTERNOON THANKS TO STRONG SOUTHWEST FLOW
BLOWING IN OFF THE NORTHEAST END OF THE LAKE. A SIMILAR TREND MAY BE
SEEN NORTHEAST OF LAKE ONTARIO A BIT LATER IN THE DAY AS WELL. THERE
WILL NOT BE MUCH COOLING ASSOCIATED WITH THE PASSAGE OF THE SURFACE
TROUGH AS HIGHS ON SUNDAY WILL STILL BE IN THE UPPER 70S TO LOWER
80S.

EXPECT MAINLY DRY CONDITIONS SUNDAY NIGHT WITH WEAK RIDGING ALOFT
AND AT THE SURFACE. TEMPERATURES SUNDAY NIGHT WILL REMAIN ON THE
WARM SIDE WITH LOWS MAINLY IN THE LOW TO MID 60S.

A WARM AND STICKY AIRMASS WILL REMAIN ACROSS THE REGION ON MONDAY
WITH CHANCES FOR SHOWERS AN THUNDERSTORMS MAINLY IN THE AFTERNOON
AND EVENING. STEEPENING LOW LEVEL LAPSE RATES AND CAPES NEARING OR
EVEN BETTERING 1000 J/KG BY LATER IN THE DAY WILL HELP TO INCREASE
INSTABILITY. BEST CHANCES FOR CONVECTION WILL BE ALONG ANY LAKE
BREEZES AND THE HIGHER TERRAIN ACROSS THE SOUTHERN TIER.
TEMPERATURES WILL AGAIN BE ON THE WARM SIDE WITH HIGHS IN THE UPPER
70S TO LOWER 80S.

WITH THE LOSS OF DAYTIME HEATING MONDAY NIGHT MOST OF THE DIURNALLY
DRIVEN CONVECTION WILL DIMINISH IN COVERAGE...ALTHOUGH A FEW
ISOLATED STORMS MAY CONTINUE LATE INTO THE EVENING...ESPECIALLY
ACROSS THE SOUTHERN TIER. AT THE SAME TIME A COLD FRONT OVER THE
UPPER GREAT LAKES WILL BE ADVANCING TOWARD THE REGION AND BE LOCATED
JUST WEST OF NEW YORK STATE BY EARLY TUESDAY MORNING. THAT
SAID...THE NIGHT LOOKS TO REMAIN DRY FOR THE MOST PART...WITH PRECIP
CHANCES STARTING TO INCREASE A BIT ACROSS WESTERN NEW YORK TOWARD
EARLY TUESDAY MORNING. ANOTHER MILD NIGHT CAN BE EXPECTED WITH LOWS
IN THE MID TO UPPER 60S FOR MOST LOCATIONS THANKS TO DEEP SOUTHERLY
FLOW JUST AHEAD OF THE APPROACHING COLD FRONT.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A PACIFIC BASED COLD FRONT WILL CROSS THE REGION ON TUESDAY. EXPECT
SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THE FRONT.
BOTH THE GFS AND THE ECMWF BRING THE LEADING EDGE OF THE
PRECIPITATION INTO FAR WESTERN NEW YORK TUESDAY MORNING...HOWEVER
THE ECMWF DEVELOPS A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER
THE OHIO VALLEY. THIS LOW THEN RIDES NORTHEAST ALONG THE FRONT AS IT
PRESSES ACROSS NEW YORK STATE. THIS WOULD SLOW THE FRONT DOWN A
BIT...WHILE ALSO POTENTIALLY GIVING THE AREA A BIT MORE IN THE WAY
OF RAINFALL. ALTHOUGH THE MAIN RAIN CHANCES WILL BE TUESDAY...WILL
HANG ONTO CHANCE POPS THROUGH THE OVERNIGHT WITH CHANCES LESSENING
FROM WEST TO EAST DUE TO THE POTENTIAL OF THE SYSTEM SLOWING DOWN A
BIT AS SHOWN BY THE ECMWF. PACIFIC BASED AIR BEHIND THIS FRONT WILL
ONLY DROP TEMPERATURES A HANDFUL OF DEGREES WITH HIGHS IN THE MIDDLE
TO UPPER 70S AND LOWS IN THE UPPER 50S TO LOWER 60S.

UPPER LEVEL RIDGING AND SURFACE HIGH PRESSURE WILL BUILD ACROSS THE
REGION WEDNESDAY AND THURSDAY BRINGING IN DRIER AIR AND TEMPERATURES
THAT WILL STILL AVERAGE AT OR JUST A BIT ABOVE NORMAL FOR EARLY
SEPTEMBER. HIGH PRESSURE WILL THEN SLIDE OFF THE NEW ENGLAND COAST
BY FRIDAY. THIS WILL PROVIDE MAINLY DRY CONDITIONS THROUGH
MIDWEEK...BEFORE THE NEXT FRONTAL SYSTEM APPROACHES FOR LATE IN THE
WEEK.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT 18Z...VFR CONDITIONS WERE IN PLACE ACROSS THE REGION WITH MOSTLY
SUNNY SKIES OUTSIDE OF A FEW MID-HIGH CLOUDS. EXPECT DIURNAL
CUMULUS TO DEVELOP THIS AFTERNOON AS MORE MOIST AIR BUILDS IN
BEHIND A WARM FRONT WITH INCREASING MOISTURE. THESE SHOULD STILL
BE IN THE VFR CATEGORY...AROUND 4-5K FEET...WITH WIDELY SCATTERED
SHOWERS AND THUNDERSTORMS INLAND FROM THE LAKES AND NOT LIKELY TO
IMPACT ANY TAF SITES.

VFR CONDITIONS SHOULD PERSIST THROUGH THIS EVENING UNTIL A MID
LEVEL DISTURBANCE AND SURFACE TROUGH WILL BRING INCREASING CHANCES
OF SHOWERS AND SCATTERED THUNDERSTORMS LATE THIS EVENING AND OVERNIGHT.
THIS IS LIKELY TO LOWER CIGS LATE TONIGHT AND SUNDAY
MORNING. THE S-SW FLOW SHOULD HELP DOWNSLOPE BUF/IAG/ROC/ART WHICH
WILL KEEP THEM MAINLY IN THE VFR/MVFR CATEGORY...WHILE HIGHER
ELEVATION AND THE LACK OF DOWNSLOPE SHOULD ALLOW IFR OR LOWER CIGS
AT JHW...AND POSSIBLY SOME FOG. CONDITIONS SHOULD IMPROVE
SUNDAY...FIRST DOWNWIND OF LAKE ERIE AT BUF/IAG...THEN SPREADING
INLAND IN THE AFTERNOON.

OUTLOOK...
SUNDAY NIGHT...IFR-VFR WITH PATCHY FOG POSSIBLE.
MONDAY...VFR/MVFR IN SCATTERED SHOWERS AND THUNDERSTORMS.
TUESDAY...SHOWERS AND THUNDERSTORMS LIKELY.
WEDNESDAY AND THURSDAY...VFR.

&&

.MARINE...
HIGH PRESSURE WILL MOVE FURTHER OUT TO SEA AS A WEAK AREA OF LOW
PRESSURE TRACKS ACROSS SOUTHERN QUEBEC ON SUNDAY. THERE WILL BE A
SOUTHERLY FLOW AHEAD OF THIS...WHICH WILL RESULT IN CHOPPY
CONDITIONS ACROSS NORTHEASTERN PORTIONS OF LAKE ONTARIO FROM GALLOO
ISLAND TO CAPE VINCENT. WAVES SHOULD RUN ABOUT 2 TO 4 FEET. WINDS
WILL THEN SHIFT TO THE SOUTHWEST BEHIND THE TROUGH OF LOW
PRESSURE...WITH THE STRONGEST WINDS ON LAKE ERIE DURING THE DAY
SUNDAY. THIS SHOULD BRING AROUND A 6 HOUR PERIOD OF 3 TO 5 FOOT
WAVES ACROSS NORTHEASTERN PORTIONS OF LAKE ERIE AS WAVES BUILD
IN THE SOUTHWESTERLY FETCH. BASED ON THIS...HAVE ISSUED THE SMALL
CRAFT HEADLINE FOR LAKE ERIE...BUT HELD OFF ON LAKE ONTARIO FOR
NOW.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EDT SUNDAY FOR LEZ040-
         041.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...JM
LONG TERM...JM
AVIATION...APFFEL
MARINE...APFFEL



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