Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 311512
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1112 AM EDT SUN AUG 31 2014

.SYNOPSIS...
A SLOW MOVING TROUGH OF LOW PRESSURE WILL PRODUCE SHOWERS AND A
FEW THUNDERSTORMS TODAY BEFORE SLOWLY TAPERING OFF FROM NORTHWEST
TO SOUTHEAST THIS AFTERNOON. IT WILL REMAIN MUGGY ALTHOUGH
EXTENSIVE CLOUD COVER WILL KEEP TEMPERATURES LOWER THAN YESTERDAY.
A FEW SPOTTY SHOWERS AND THUNDERSTORMS ARE POSSIBLE ON LABOR
DAY...BUT THE MAJORITY OF THE DAY SHOULD BE RAIN FREE WITH
TEMPERATURES WARMING BACK TO A LITTLE ABOVE AVERAGE.

&&

.NEAR TERM /THROUGH TONIGHT/...
RADAR IMAGERY LATE THIS MORNING SHOWS A SOLID AREA OF RAIN ACROSS
CENTRAL NEW YORK...JUST ABOUT TO EXIT EAST OF OUR CWA. BEHIND
THIS...BROKEN LINES OF SHOWERS WITH EMBEDDED THUNDERSTORMS HAVE
DEVELOPED AHEAD OF A WIND SHIFT BOUNDARY WHICH EXTENDS FROM SW-NE
AND IS LOCATED NEAR BUFFALO AT 1100 AM. THIS BOUNDARY WILL
CONTINUE TO MOVE EAST IN ASSOCIATION WITH A MID LEVEL TROUGH. THE
12Z BUF SOUNDING HAS AN IMPRESSIVE 1.83 INCH PWAT...SO SHOWERS AND
THUNDERSTORMS WHICH DO DEVELOP AHEAD OF THIS BOUNDARY WILL PRODUCE
BRIEF HEAVY DOWNPOURS...BUT ARE LIKELY TO MOVE WITH THE BOUNDARY WHICH
SHOULD MITIGATE FLOOD POTENTIAL. IT IS STILL FAIRLY MOIST BEHIND
THIS BOUNDARY...AND WITH A LAKE BREEZE CONVERGENCE BOUNDARY
EXPECTED TO DEVELOP NEAR THE SOUTH SHORES OF LAKE ONTARIO THERE
COULD BE A FEW SHOWERS OR THUNDERSTORMS WHICH DEVELOP ON THIS
BOUNDARY. HOWEVER...MOST MESOSCALE GUIDANCE FROM THE HRRR TO
NAM/RGEM FOCUS THE STEADIEST SHOWERS ACROSS EAST OF EACH
LAKE...OUT AHEAD OF THE BOUNDARY.

SOUTHWESTERLY WINDS WILL PICK UP ACROSS THE NIAGARA FRONTIER THIS
AFTERNOON...WHICH SHOULD PROVIDE AT LEAST A PARTIAL CLEARING BY
MIXING OUT LOW MOISTURE. TEMPERATURES ALOFT ARE STILL WARM...WITH
SURFACE TEMPERATURES LIKELY TO REACH 80 IN ANY AREAS WHICH GET
PROLONGED SUNSHINE. SOUTHERN AND EASTERN PORTIONS OF THE CWA
SHOULD STAY STUCK IN THE CLOUDS...WITH HIGHS AVERAGING IN THE MID
70S.

TONIGHT SHOWERS ACROSS THE SOUTHERN TIER AND CENTRAL NY WILL
CONTINUE TO SLOWLY DIMINISH. ENOUGH INSTABILITY MAY DEVELOP IN THE
WAKE OF THIS MAIN RAIN AREA TO ALLOW SCATTERED THUNDERSTORMS TO FORM
DURING THE LATE AFTERNOON AND EARLY EVENING ACROSS THE NIAGARA
PENINSULA. IF THEY MATERIALIZE...A FEW MAY MAKE IT INTO AREAS JUST
NORTH OF BUFFALO THIS EVENING. SCATTERED STORMS MAY ALSO FORM OVER
SOUTHEAST ONTARIO AND CROSS THE SAINT LAWRENCE INTO THE NORTH
COUNTRY THIS EVENING. OTHERWISE EXPECT SOME PARTIAL CLEARING
OVERNIGHT ON THE LAKE PLAINS. ACROSS THE HIGHER TERRAIN LOW LEVEL
MOISTURE AND WEAK UPSLOPE FLOW AND CONVERGENCE WILL LIKELY SUPPORT
EXPANDING LOW CLOUD COVER. EXPECT LOWS IN THE MID TO UPPER 60S ON
THE LAKE PLAINS AND LOWER TO MID 60S IN THE SOUTHERN TIER AND NORTH
COUNTRY.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A WARM AND STICKY AIRMASS WILL REMAIN ACROSS THE REGION ON
MONDAY...WITH MOST OF THE FORECAST AREA EXPERIENCING MAINLY DRY
CONDITIONS. HOWEVER THERE WILL BE THE CHANCE FOR SCATTERED SHOWERS
AND THUNDERSTORMS IN THE AFTERNOON AND EVENING...MAINLY ACROSS THE
INTERIOR SOUTHERN TIER WHERE THE BEST INSTABILITY WILL RESIDE. CAPE
VALUES BY LATER IN THE AFTERNOON ACROSS THIS REGION WILL RUN IN THE
1000-1500 J/KG RANGE WITH LI`S POSSIBLY AS LOW AS -4. HOWEVER WITH
WEAK 0-6KM BULK SHEAR (~20KTS) AND LACK OF A GOOD SURFACE TRIGGER
(ASIDE FROM A POSSIBLE LAKE BREEZE)...NOT EXPECTING ANY
THUNDERSTORMS TO REACH SEVERE LIMITS. INSTABILITY LOOKS LOWER ACROSS
THE REMAINDER OF THE AREA...AND THUS CONVECTIVE CHANCES LOOK MUCH
LOWER AS WELL. 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 STORMS
MAY CONTINUE LATE INTO THE EVENING...ESPECIALLY ACROSS PORTIONS OF
THE SOUTHERN TIER. AT THE SAME TIME A COLD FRONT OVER THE UPPER
GREAT LAKES WILL BE ADVANCING TOWARD THE REGION AND BE LOCATED WEST
OF NEW YORK STATE BY TUESDAY MORNING. THAT SAID...MOST OF THE NIGHT
LOOKS TO REMAIN DRY...WITH PRECIP CHANCES STARTING TO INCREASE A BIT
ACROSS WESTERN NEW YORK TOWARD TUESDAY MORNING. ANOTHER MILD
NIGHT CAN BE EXPECTED WITH LOWS IN THE MID TO UPPER 60S FOR MOST
LOCATIONS THANKS TO DEEP SOUTHERLY FLOW OUT AHEAD OF THE APPROACHING
COLD FRONT.

LATEST GUIDANCE PACKAGE HAS THE COLD FRONT NOW MOVING A BIT SLOWER
THAN IN PREVIOUS RUNS. THIS IS MOST LIKELY DUE TO MOST OF THE MODELS
NOW COMING INTO AGREEMENT ON THE DEVELOPMENT OF LOW PRESSURE
SOMEWHERE IN THE OHIO VALLEY ALONG THE FRONT AND THEN TRACKING IT
NORTHEAST ALONG THE BOUNDARY WHICH WOULD SLOW IT DOWN A LITTLE.
THAT SAID...IT NOW APPEARS IT WILL TAKE THE BULK OF THE DAY TUESDAY
FOR THE COLD FRONT TO SWEEP ACROSS THE REGION WITH SHOWERS AN
THUNDERSTORMS LIKELY...WITH LOWER CHANCE POPS BY LATER IN THE DAY
ACROSS WESTERN NEW YORK. HIGH PRECIPITABLE WATER VALUES OF 1.7"-1.9"
TUESDAY AFTERNOON OFFER THE RISK OF HEAVY DOWNPOURS WITH ANY
THUNDERSTORM. SBCAPES OVER 1000 J/KG COMBINED WITH LIFTED INDEX
VALUES AT -4C TO -5C ALSO POINT TO THE POSSIBILITY OF STORMS. THE
MAIN DIFFERENCES FROM MONDAY ARE THAT 0-6KM BULK SHEAR VALUES LOOK
TO BE IN THE 40-45KT RANGE...AND ALSO HAVE THE SURFACE COLD FRONT
CROSSING THE FORECAST AREA WHICH WILL SERVE AS THE FOCAL POINT FOR
STORMS TO FIRE ALONG. ALL THIS SAID...LOOKS AS THOUGH THERE COULD BE
SOME STRONG STORMS...WITH A FEW STORMS POSSIBLY REACHING SEVERE
LIMITS. MAIN THREATS APPEAR TO BE GUSTY WINDS ASSOCIATED WITH BOWING
LINE SEGMENTS AND MARGINALLY SEVERE HAIL. ANOTHER WARM DAY ON TAP
WITH HIGHS IN THE UPPER 70S TO LOWER 80S.

THE COLD FRONT WILL SLIDE SOUTH AND EAST OF THE FORECAST AREA
TUESDAY EVENING...TAKING THE SHOWERS AND STORMS WITH IT. ALTHOUGH A
FEW SHOWERS WILL STILL BE POSSIBLE DURING THE EVENING ACROSS EASTERN
AREAS...BUT EVEN HERE THINGS WILL DRY OUT LATER TUESDAY NIGHT AS
SURFACE HIGH PRESSURE STARTS TO BUILD EAST ACROSS NEW YORK STATE.
LOWS WILL BE GENERALLY IN THE UPPER 50S TO LOWER 60S.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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 AND EARLY WEEKEND. TEMPERATURES WILL BE A BIT ABOVE SEASONAL
NORMALS WITH HIGHS IN THE UPPER 70S TO LOW 80S AND LOWS IN THE LOWER
60S.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
CONDITIONS HAVE LOWERED LATE THIS MORNING...WITH THE APPROACH OF A
SURFACE TROUGH AN IN HEAVIER RAIN SHOWERS. LOW VSBY IN RAIN
SHOWERS...AND A FEW EMBEDDED THUNDERSTORMS SHOULD BE
TEMPORARY. EXPECT A MIX OF MVFR/VFR CIGS AT BUF/IAG/ROC/ART WITH
THE SW WIND SHIFT...WHILE JHW IS LIKELY TO REMAIN IFR OR LOWER AND
THEN IMPROVE WITH THE WIND SHIFT.

TONIGHT ANY SHOWERS AND SCATTERED THUNDER ACROSS THE SOUTHERN TIER
WILL DIMINISH DURING THE EVENING. MAINLY VFR DURING THE EVENING WILL
GIVE WAY TO INCREASING AMOUNTS OF IFR IN LOW STRATUS OVERNIGHT WITH
EXTENSIVE LOW LEVEL MOISTURE FIELDS. EXPECT STRATUS TO FORM FIRST
ACROSS HIGHER TERRAIN...BUT MAY SPREAD TO THE LOWER ELEVATIONS OF
WESTERN NY AS WELL AFTER ABOUT 09Z. AREAS OF FOG AND IFR VSBY ARE
LIKELY ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER AND FINGER
LAKES AS WELL WHERE THE LOW STRATUS INTERSECTS THE HILLS.

OUTLOOK...
MONDAY...VFR/MVFR IN SCATTERED SHOWERS AND THUNDERSTORMS.
TUESDAY...SHOWERS AND THUNDERSTORMS LIKELY WITH ASSOCIATED BRIEF
MVFR/IFR. SOME STORMS MAY BE STRONG.
WEDNESDAY AND THURSDAY...VFR.

&&

.MARINE...
MODERATE SOUTHERLIES WILL CONTINUE TO PRODUCE MARGINAL SMALL CRAFT
ADVISORY CONDITIONS AT THE NORTHEAST END OF LAKE ONTARIO FROM GALLOO
ISLAND TO CAPE VINCENT THROUGH EARLY AFTERNOON BEFORE
DIMINISHING. LOW PRESSURE WILL MOVE ACROSS SOUTHERN QUEBEC TODAY
WITH WINDS BECOMING MORE SOUTHWEST ON THE LOWER LAKES. EXPECT
WINDS TO INCREASE ABRUPTLY ON LAKE ERIE THROUGH EARLY
AFTERNOON...WITH A 3 TO 6 HOUR PERIOD OF 15 TO 20 KNOT WINDS AND 3
TO 5 FOOT WAVES AS WINDS ALOFT SHIFT TO THE WSW AND MIX DOWN
AS THEY ENCOUNTER THE CHAUTAUQUA RIDGE. ALSO...THERE IS A
CONVERGENCE BOUNDARY ON LAKE ERIE WHICH HAS THE POTENTIAL TO
PRODUCE WATER SPOUTS THROUGH EARLY AFTERNOON. THIS POTENTIAL WILL
END AS THE BOUNDARY SLIDES FURTHER SOUTH AND OFF THE LAKE.

THE PRESSURE GRADIENT RELAXES ACROSS THE LOWER LAKES TONIGHT AS LOW
PRESSURE DISSIPATES OVER SOUTHEAST QUEBEC. THIS WILL ALLOW WINDS AND
WAVES TO SUBSIDE.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON
         FOR LOZ045.

&&

$$

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







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