Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 021209
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
809 AM EDT TUE SEP 2 2014

.SYNOPSIS...
A FEW SCATTERED LIGHT SHOWERS WILL CONTINUE ACROSS WESTERN NEW YORK
THROUGH MID MORNING BEFORE A COLD FRONT SLOWLY CROSSES THE REGION
THIS AFTERNOON THROUGH THIS EVENING WITH MORE WIDESPREAD SHOWERS AND
THUNDERSTORMS...SOME OF WHICH COULD PRODUCE STRONG GUSTY WINDS AND
HEAVY RAINFALL. IN THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD
INTO THE LOWER GREAT LAKES AND BRING A RETURN TO DRIER AND LESS
HUMID WEATHER WEDNESDAY AND THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS AT 12Z THIS MORNING SHOWING JUST A FEW LIGHT SHOWERS
MOVING ACROSS THE NORTHERN FINGER LAKES...WITH QUIET CONDITIONS
ELSEWHERE. THESE WILL CONTINUE TO WANE THROUGH MID MORNING. AFTER
THAT...EXPECT THE AREA WILL REMAIN MAINLY DRY OUTSIDE OF THE
POSSIBILITY OF A FEW POP UP LIGHT SHOWERS LATER THIS MORNING.

THE AXIS OF BROAD MID AND UPPER LEVEL TROUGHING WILL SLIDE EAST
FROM THE UPPER GREAT LAKES TO THE LOWER LAKES REGION TODAY WITH AN
ASSOCIATED WEAK COLD FRONT EASING EASTWARD ACROSS THE FORECAST AREA
FROM LATE THIS MORNING THROUGH THIS EVENING. EXPECT PRECIPITATION TO
MOVE INTO WESTERN NEW YORK LATER THIS MORNING ON THE NOSE OF 30-35KT
850MB JET...THEN REACHING NORTHCENTRAL NEW YORK BY EARLY TO MID
AFTERNOON. SHOWERS AND STORMS WILL TAPER OFF FROM WEST TO EAST
THROUGH THIS EVENING. THUNDERSTORM POTENTIAL REMAINS HIGH WITH
FORECAST SBCAPES GENERALLY RUNNING BETWEEN 1000-1500 J/KG COMBINED
WITH LIFTED INDEX VALUES AROUND -2C TO -3C. 0-6KM BULK SHEAR HAS
ALSO INCREASED TO 40-45KT ACROSS MOST OF THE REGION JUST AHEAD OF
THE FRONT...MAKING THE CHANCES OF A FEW STORMS REACHING SEVERE
LIMITS EVEN BETTER. IN ADDITION...WILL HAVE INCREASING UPPER LEVEL
DIFFLUENCE IN THE RIGHT ENTRANCE REGION OF A 110+ KNOT UPPER LEVEL
JET NEARING THE REGION. KEY FACTOR STILL APPEARS TO BE THE AMOUNT OF
SURFACE HEATING THAT TAKES PLACE BEFORE FROPA...I.E. WILL CLOUD
COVER MOVE IN TOO EARLY AND LIMIT HEATING...AND THUS THE AMOUNT OF
INSTABILITY. BETTER SURFACE HEAT LOOKS MORE LIKELY NOW AS THE FRONT
APPEARS TO BE MOVING A BIT SLOWER TAKING A LOOK AT THE LATEST
GUIDANCE PACKAGE...INCLUDING THE 06Z NAM. AREAS FROM THE SOUTHERN
TIER NORTHEAST THROUGH THE FINGER LAKES REGION AND NORTH COUNTRY
HAVE THE BEST SHOT AT SEEING THE MOST SUNSHINE OUT AHEAD OF THE
FRONT...SO THESE LOOK TO BE THE MOST FAVORED AREAS FOR STRONGER
STORMS. THESE AREAS ARE ALSO OUTLINED BY A SLIGHT RISK (15%) AREA
FROM SPC...WITH THE REMAINDER OF THE AREA UNDER A 5% RISK. TO
ADD...HIGH PRECIPITABLE WATER VALUES OF 1.7"-1.8" OUT AHEAD OF THE
BOUNDARY OFFERS THE RISK FOR HEAVY DOWNPOURS WITH ANY THUNDERSTORM.
ALL THESE FACTORS TAKEN INTO CONSIDERATION...IT APPEARS THERE WILL
BE SOME STRONG STORMS...WITH A FEW STORMS POSSIBLY REACHING SEVERE
LIMITS. MAIN THREATS APPEAR TO BE GUSTY WINDS ASSOCIATED WITH ANY
BOWING LINE SEGMENTS AND LOCALLY HEAVY RAINFALL. IT WILL BE ANOTHER
WARM DAY WITH HIGHS MAINLY IN THE UPPER 70S TO LOWER 80S.

THE COLD FRONT WILL SLIDE SOUTH AND EAST OF THE FORECAST AREA
TONIGHT...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 LOCATED ACROSS THE OHIO VALLEY STARTS TO BUILD
EAST ACROSS THE REGION. LOWS WILL BE GENERALLY IN THE UPPER 50S TO
LOWER 60S.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
BY WEDNESDAY MORNING THE MID LEVEL TROUGH WILL HAVE LIFTED INTO
EASTERN QUEBEC WITH SURFACE HIGH PRESSURE BUILDING INTO THE OHIO
VALLEY. THIS WILL BRING A RETURN TO DRY WEATHER ON WEDNESDAY WITH
DRYING AND SUBSIDENCE ON THE INCREASE. THERE MAY BE SOME LINGERING
LOW LEVEL MOISTURE AND CLOUDS ACROSS THE HIGHER TERRAIN DURING THE
MORNING. DIURNAL CUMULUS FIELDS MAY ALSO DEVELOP ACROSS THE HIGHER
TERRAIN OF THE SOUTHERN TIER AND FINGER LAKES...AND ALSO ALONG A
CONVERGENCE ZONE RUNNING FROM THE NIAGARA PENINSULA TO NEAR
ROCHESTER. THIS MAY YIELD A MIX OF CLOUDS AND SUN IN THESE AREAS FOR
THE AFTERNOON. 850MB TEMPS OF AROUND +12C WILL SUPPORT HIGHS AROUND
80 AT THE LOWER ELEVATIONS OF WESTERN NY WITH MID TO UPPER 70S
ACROSS HIGHER TERRAIN AND THE NORTH COUNTRY.

HIGH PRESSURE WILL BUILD NORTHEAST INTO NEW ENGLAND WEDNESDAY NIGHT
AND THURSDAY WITH RIDGING EXTENDING BACK INTO THE LOWER LAKES. THIS
WILL PROVIDE MORE DRY WEATHER WITH MAINLY CLEAR SKIES MUCH OF THE
TIME. EXPECT DECENT RADIATIONAL COOLING CONDITIONS WEDNESDAY NIGHT
ALTHOUGH THE AIRMASS IS NOT PARTICULARLY COOL OR DRY. LOWS WILL
RANGE FROM AROUND 60 ON THE LAKE PLAINS TO AROUND 50 IN THE COOLEST
SOUTHERN TIER VALLEYS AND TUG HILL REGION.

WARM ADVECTION WILL INCREASE DURING THE DAY THURSDAY. ISENTROPIC
UPGLIDE AND INCREASING MOISTURE MAY PRODUCE SOME PATCHY MID LEVEL
CLOUDS...BUT THE THICKER CLOUD COVER SHOULD REMAIN ON THE CANADIAN
SIDE OF THE INTERNATIONAL BORDER. 850MB TEMPS RISE TO +14C TO +16C
BY THURSDAY AFTERNOON...SUPPORTING HIGHS IN THE MID 80S ACROSS LOWER
ELEVATIONS.

THURSDAY NIGHT WARM ADVECTION WILL INCREASE AS SOUTHWEST FLOW PICKS
UP IN RESPONSE TO A STRONG COLD FRONT MOVING INTO THE WESTERN LAKES.
ONGOING WARM ADVECTION AND ISENTROPIC UPGLIDE WILL BRING SOME
INCREASE IN MID/HIGH CLOUDS. A WARMER AIRMASS AND A MIXING BREEZE
OVERNIGHT WILL KEEP LOWS ON THE WARM SIDE WITH UPPER 60S ON THE LAKE
PLAINS AND LOWER 60S IN THE SHELTERED SOUTHERN TIER VALLEYS AND TUG
HILL REGION.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
THE LONG TERM WILL BE VERY CHANGEABLE WITH ONE OF THE WARMEST DAYS
OF THE YEAR ON FRIDAY FOLLOWED BY A SIGNIFICANT COOL DOWN FOR THE
WEEKEND.

ON FRIDAY A STRONG AND PROGRESSIVE MID LEVEL TROUGH WILL MOVE ACROSS
NORTHWEST ONTARIO TO JAMES BAY. INCREASING SOUTHWEST FLOW AHEAD OF
THIS FEATURE WILL CAPTURE AN ELEVATED MIXED LAYER /EML/ WITH ORIGINS
ACROSS THE DESERT SOUTHWEST. THIS EML PLUME WILL ALLOW 850MB TEMPS
TO SOAR TO AROUND +18C TO +19C. THIS WILL SUPPORT HIGHS IN THE UPPER
80S TO LOWER 90S IN MANY AREAS...WITH THE WARMEST TEMPS LIKELY TO BE
IN THE GENESEE VALLEY. THE EML PLUME WILL PROVIDE A STRONG CAP IN
THE WARM SECTOR AND SHOULD HOLD CONVECTION AT BAY UNTIL AT LEAST
LATE AFTERNOON WHEN THE UPSTREAM COLD FRONT AND TROUGH APPROACH AND
AID IN ERODING THE MID LEVEL CAP.

FRIDAY NIGHT COULD BE ACTIVE WITH A STRONG SURFACE COLD FRONT
DROPPING SOUTHEAST ACROSS THE REGION. THE STRONGEST HEIGHT FALLS AND
UPPER LEVEL SUPPORT WILL SHIFT EAST ACROSS QUEBEC...ALTHOUGH A
TRAILING RIBBON OF STRONGER FLOW IN THE 900-700MB LAYER WILL PROVIDE
ENOUGH CONVERGENCE TO ORGANIZE A BROKEN BAND OF CONVECTION ALONG THE
FRONT. GIVEN THE STRENGTH OF THE FRONT AND BETTER AGREEMENT BETWEEN
THE GFS AND ECMWF ON TIMING...HAVE BUMPED POPS TO LOW LIKELY FOR
FRIDAY NIGHT.

BY SATURDAY MODEL DIFFERENCES BEGIN TO SHOW...WITH THE ECMWF
DEVELOPING A WEAK FRONTAL WAVE IN THE MID ATLANTIC. THIS WOULD HOLD
UP THE FRONT SOMEWHAT AND ALSO FORCE IT TO BECOME MORE ANABATIC IN
NATURE WITH SHOWERS LINGERING ON THE COOL SIDE OF THE BOUNDARY. THE
GFS HAS A FASTER COLD FRONTAL PASSAGE WITH SATURDAY DRY. FOR NOW
WILL HOLD ONTO LOW CHANCE POPS FOR SATURDAY WITH A HEDGE TO THE
SLOWER ECMWF SOLUTION. IN EITHER CASE IT WILL BE NOTABLY COOLER
SATURDAY...WITH HIGHS ONLY IN THE LOWER 70S IN MOST LOCATIONS.

SATURDAY NIGHT THROUGH MONDAY THE FRONT WILL PUSH WELL SOUTHEAST OF
THE REGION WITH HIGH PRESSURE BUILDING INTO THE GREAT LAKES. THIS
WILL BRING A RETURN TO MAINLY DRY WEATHER. TEMPERATURES WILL REACH
THEIR COOLEST ON SUNDAY WHEN HIGHS MAY NOT MAKE IT OUT OF THE UPPER
60S AT LOWER ELEVATIONS AND MID 60S ACROSS HIGHER TERRAIN. AIRMASS
MODERATION WILL BEGIN BY MONDAY WITH HIGHS BACK INTO THE LOWER 70S.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
MVFR CIGS HAVE FORMED ACROSS KBUF AND KART...WITH INTERMITTENT MVFR
CIGS AT KROC. IFR CIGS HAVE FORMED AT KJHW AS EXPECTED. VERY MOIST
LOW LEVELS ARE THE MAIN CONTRIBUTOR TO THE LOW CIGS. EXPECT ALL
AREAS TO BECOME VFR MID TO LATE MORNING AS LOW CLOUDS MIX OUT WITH
DIURNAL HEATING.

REGIONAL RADARS AT 12Z THIS MORNING SHOWING JUST A FEW LIGHT SHOWERS
MOVING ACROSS THE NORTHERN FINGER LAKES...WITH QUIET CONDITIONS
ELSEWHERE. THESE WILL CONTINUE TO WANE THROUGH MID MORNING. AFTER
THAT...EXPECT THE AREA WILL REMAIN MAINLY DRY OUTSIDE OF THE
POSSIBILITY OF A FEW POP UP LIGHT SHOWERS LATER THIS MORNING.

A COLD FRONT WILL SLOWLY EASE EASTWARD ACROSS THE REGION THROUGH THE
COURSE OF THE DAY. COUPLED WITH INCREASING DAYTIME
INSTABILITY...EXPECT MORE WIDESPREAD SHOWERS AND STORMS TO DEVELOP
ALONG AND AHEAD OF THIS FRONT AS IT CROSSES THE AREA THIS AFTERNOON
INTO THIS EVENING...WITH SOME OF THESE POTENTIALLY BRINGING BRIEF
PERIODS OF MVFR/IFR. A FEW OF THESE STORMS COULD EVEN BECOME STRONG
TO SEVERE ACROSS THE FORECAST AREA. OUTSIDE OF ANY SHOWERS AND
THUNDERSTORMS...EXPECT VFR FLIGHT CONDITIONS.

ALL OF THIS ACTIVITY WILL EXIT SOUTH AND EAST OF THE REGION THIS
EVENING...WITH VFR FLIGHT CONDITIONS RETURNING FOR MOST OF THE
NIGHT...WITH MVFR CEILINGS ONCE AGAIN POSSIBLE LATE IN THE TAF
PERIOD ACROSS THE INTERIOR SOUTHERN TIER.

OUTLOOK...
WEDNESDAY AND THURSDAY...VFR.
FRIDAY AND SATURDAY...A CHANCE OF SHOWERS AND THUNDERSTORMS WITH
ASSOCIATED BRIEF MVFR/IFR...OTHERWISE VFR.

&&

.MARINE...
A COLD FRONT WILL CROSS THE LOWER LAKES REGION THIS AFTERNOON AND
EVENING. IN ADVANCE OF THE FRONT...SOUTHWESTERLY WINDS WILL INCREASE
THIS MORNING...PARTICULARLY ON LAKE ERIE WHERE WINDS AND WAVES WILL
CLIMB TO NEAR ADVISORY LEVELS. IT APPEARS THAT WINDS WILL REMAIN AT
OR JUST ABOVE ADVISORY CRITERIA THROUGH LATE AFTERNOON/EARLY
EVENING...SO HAVE DECIDED TO EXTEND THE CURRENT SCA FOR LAKE ERIE
THROUGH 00Z THIS EVENING. THE FRONT ITSELF WILL ALSO PRODUCE A ROUND
OF SCATTERED TO NUMEROUS THUNDERSTORMS TODAY...OF WHICH A FEW COULD
PRODUCE STRONG GUSTY WINDS AND LOCALLY HIGHER WAVES.

IN THE WAKE OF THE FRONTAL PASSAGE...HIGH PRESSURE WILL BUILD ACROSS
THE REGION TUESDAY NIGHT THROUGH THURSDAY WHILE BRINGING A RETURN TO
FAIR WEATHER AND LIGHTER WINDS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ040-
         041.

&&

$$

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






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