Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 171844
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
244 PM EDT WED SEP 17 2014

.SYNOPSIS...
HIGH PRESSURE WILL KEEP DRY AND SLIGHTLY COOLER THAN NORMAL WEATHER
IN PLACE THROUGH THIS EVENING. A WEAK COLD FRONT WILL THEN CROSS THE
REGION LATER TONIGHT AND THURSDAY MORNING...AND MAY BRING A LIGHT
SHOWER OR TWO TO AREAS EAST OF LAKE ONTARIO. FOLLOWING THE
FRONT...CANADIAN HIGH PRESSURE AND A REINFORCING SHOT OF NOTICEABLY
COOLER AIR WILL BRIEFLY OVERSPREAD OUR AREA THURSDAY AND THURSDAY
NIGHT...BEFORE A MODERATING TREND SETS IN FOR FRIDAY AND SATURDAY.
THE NEXT MORE WIDESPREAD CHANCE OF RAIN WILL ARRIVE THIS
WEEKEND...WHEN A COMPLEX FRONTAL SYSTEM IS FORECAST TO CROSS OUR
REGION.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SPRAWLING HIGH PRESSURE WILL SLIDE SOUTH OF NEW YORK STATE THIS
EVENING KEEPING DRY CONDITIONS IN PLACE. VISIBLE SATELLITE IMAGERY
STILL SHOWING A DISORGANIZED BAND OF LAKE EFFECT CLOUDS ALONG A
CONVERGENT BOUNDARY SLICING DOWN THE MIDDLE OF LAKE ERIE. THESE
CLOUDS WILL CONTINUE TO BREAK UP THIS AFTERNOON...WHILE LAKE ONTARIO
IS VIRTUALLY CLOUD FREE.

THAT SAID...DAYTIME HEATING HAS BROUGHT ABOUT A DIURNAL CU FIELD AS
EXPECTED ACROSS ALL AREAS JUST INLAND FROM THE LAKES. AREAS JUST
EAST AND NORTHEAST OF THE LAKES ARE SEEING THE MOST SUN THANKS TO
LAKE SHADOWING. DIURNAL CU FIELD WILL DISSIPATE LATER THIS AFTERNOON
INTO EARLY THIS EVENING AS DAYTIME HEATING WANES.

SOME MID AND HIGH CLOUDS ARE NOW STARTING TO WORK INTO FAR NORTHERN
PORTIONS OF NEW YORK STATE IN ADVANCE OF A WEAK COLD FRONT SLOWLY
PRESSING IN OUR DIRECTION FROM ONTARIO/QUEBEC PROVINCES...THOUGH
EVEN THERE SKIES WILL BECOME NO WORSE THAN PARTLY SUNNY.

TONIGHT...THE WEAK COLD FRONT WILL SLOWLY SAG FROM SOUTHERN ONTARIO/
QUEBEC INTO WESTERN AND NORTH CENTRAL NEW YORK IN RESPONSE TO A
SUBTLE SHARPENING OF THE MID AND UPPER LEVEL FLOW...WITH THIS
FEATURE REACHING OR AT LEAST NEARING A BUFFALO-ROCHESTER-SYRACUSE
AXIS BY 12Z THURSDAY. WITH THE BOUNDARY APPEARING ANAFRONTAL IN
NATURE...ANY NOTICEABLE INCREASE IN CLOUD COVER SHOULD REMAIN
CONFINED TO AREAS ALONG AND NORTH OF THE BOUNDARY...WHILE AREAS
FURTHER SOUTH REMAIN MAINLY CLEAR TO PARTLY CLOUDY.

GIVEN THE LACK OF SIGNIFICANT UPPER LEVEL SUPPORT AND THAT THE BULK
OF ANY MOISTURE SHOULD REMAIN CONFINED TO THE LOWEST 5-10 KFT OF THE
ATMOSPHERE...PRECIP CHANCES ATTENDANT TO THE ENCROACHING FRONT STILL
APPEAR TO BE FAIRLY MINIMAL TONIGHT AND TOMORROW MORNING. THIS
NOTED...A FEW LIGHT SHOWERS STILL APPEAR POSSIBLE ACROSS THE NORTH
COUNTRY/SAINT LAWRENCE VALLEY OVERNIGHT...AND ACROSS WESTERN NEW
YORK TOMORROW MORNING ALONG AND JUST BEHIND THE FRONT AS IT SAGS
SOUTHWARD. OVERNIGHT LOWS WILL RANGE FROM THE LOWER 40S ACROSS THE
HIGHER TERRAIN...TO THE UPPER 40S ALONG THE LAKE SHORES.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
A COLD FRONT WILL SAG SOUTH ACROSS LAKE ONTARIO AND SETTLE ACROSS
NEW YORK STATE ON THURSDAY. WHILE THE FRONT MAY BRING A FEW
SPRINKLES...PARTICULARLY ACROSS UPSLOPE AREAS SOUTH OF LAKE
ONTARIO...MOISTURE WILL BE VERY SHALLOW DUE TO THE ARCTIC AIRMASS
ADVECTING INTO THE REGION BEHIND THE FRONT AND ASIDE FROM A FEW
SPRINKLES THE MAIN EFFECTS WILL BE ABUNDANT LAKE ENHANCED CLOUDINESS
ACROSS MUCH OF THE FORECAST AREA. THE EXCEPTION WILL BE THE NORTH
COUNTRY WHICH WILL ESCAPE THE LAKE INFLUENCES AND HAVE GREATER
EXPOSURE TO THE COOL DRY AIR FLOWING SOUTH OUT OF CANADA.

THE COMBINATION OF COLD ADVECTION AND ABUNDANT CLOUD COVER WILL KEEP
TEMPERATURES IN THE 50S ON THURSDAY. TEMPERATURES WILL PLUNGE
THURSDAY NIGHT AS ARCTIC HIGH PRESSURE MOVES OVERHEAD AND CLOUD COVER
DISSIPATES. WITH LIGHT WINDS...CLEARING SKIES AND LOWERING
DEWPOINTS...THE POTENTIAL FOR FROST WILL EXTEND ACROSS MUCH OF
WESTERN AND NORTH-CENTRAL NEW YORK WITH THE EXCEPTION OF AREAS
IMMEDIATELY ADJACENT TO THE LAKES. THE COLDEST READINGS WILL BE
FOUND ACROSS THE NORTH COUNTRY WHICH WILL BE IN CLOSEST PROXIMITY TO
THE COLDEST AND DRIEST AIR ACROSS QUEBEC. HERE READINGS ARE LIKELY
TO DIP BELOW FREEZING INLAND FROM THE LAKES AND A FREEZE WATCH HAS
BEEN ISSUED FOR LATE THURSDAY NIGHT AND EARLY FRIDAY MORNING.

AFTER A CHILLY START TO THE DAY FRIDAY MORNING...TEMPERATURES WILL
MODERATE NICELY AS THE HIGH MOVES OFF TO THE EAST AND THE
COMBINATION OF ABUNDANT SUBSIDENCE FROM THE HIGH AND INCREASING WARM
ADVECTION ON THE WESTERN FLANK OF THE HIGH PUSHES TEMPERATURES BACK
INTO THE MID-60S...MAKING FOR A PLEASANT AUTUMN DAY ACROSS THE
REGION.

WARM ADVECTION WILL CONTINUE TO INCREASE FRIDAY NIGHT INTO SATURDAY
AS THE HIGH MOVES OFF THE EAST COAST AND DEVELOPING LOW PRESSURE
MOVES INTO THE UPPER MIDWEST. INCREASING MOIST RETURN FLOW ACROSS
THE REGION AND WARM ADVECTION ALOFT WILL BRING INCREASING CLOUD
COVER FRIDAY NIGHT WILL YIELD MUCH MORE MILD READINGS FRIDAY NIGHT
WITH LOWS IN THE 50S. IT WILL FEEL ALMOST SUMMERLIKE SATURDAY AS A
WARM FRONT SLIDES BY TO OUR NORTH AND SOUTHERLY FLOW
STRENGTHENS...WITH ASSOCIATED DOWNSLOPING HELPING TO PUSH READINGS
INTO THE MID TO UPPER 70S ACROSS THE GENESEE VALLEY AND NORTH OF THE
FINGER LAKES WITH LOW TO MID 70S ELSEWHERE ACROSS WESTERN NEW YORK
AND SLIGHTLY COOLER TEMPERATURES IN THE NORTH COUNTRY. THE MILD
WEATHER SHOULD HANG ON FOR MORE NIGHT SATURDAY NIGHT WITH DEWPOINTS
RISING INTO THE MID TO UPPER 50S WITH OVERNIGHT LOWS IN THE UPPER
50S TO AROUND 60.

.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE QUIET STRETCH OF WEATHER ACROSS THE LOWER GREAT LAKES WILL
COME TO AN END SUNDAY AS A POTENT SHORTWAVE DROPPING OUT OF
NORTHWESTERN CANADA REINFORCES AN EXISTING SHORTWAVE TROUGH AND
WEAK SURFACE LOW OVER THE WESTERN GREAT LAKES. THE REINVIGORATED
SURFACE LOW WILL TRACK INTO QUEBEC SUNDAY WHILE THE SHORTWAVE DIGS
A DEEP UPPER LEVEL TROUGH ACROSS THE GREAT LAKES. WHILE THERE IS
BROAD AGREEMENT THAT THE RESULTANT COLD FRONT WILL SWING ACROSS
WESTERN/NORTH-CENTRAL NEW YORK SOMETIME SUNDAY INTO SUNDAY
EVENING...THERE CONTINUE TO BE DIFFERENCES IN DETAIL AND TIMING OF
SPECIFIC FEATURES. NONETHELESS GIVEN VERY STRONG SYNOPTIC FORCING
AT WORK AM CONFIDENT THAT MOST AREAS WILL SEE PRECIPITATION
SOMETIME DURING THE SUNDAY/SUNDAY NIGHT TIME FRAME. FUTURE MODEL
RUNS WILL ALLOW FOR MORE REFINEMENT OF TIMING OF THE FRONTAL
PASSAGE AND ASSOCIATED PRECIPITATION.

THE PASSAGE OF THE AFOREMENTIONED COLD FRONT WILL MARK A TRANSITION
BACK TO COOLER AUTUMNAL WEATHER ACROSS THE LOWER GREAT LAKES AS UPPER
LEVEL TROUGHING ONCE AGAIN BECOMES ESTABLISHED ACROSS THE REGION.
LOOK FOR TEMPERATURES TO FALL FROM PRE-FRONTAL HIGHS IN THE 70S
SUNDAY BACK INTO THE 60S MONDAY...WITH HIGHS POSSIBLY ONLY REACHING
THE 50S BY TUESDAY AS THE UPPER LEVEL TROUGH MOVES OVERHEAD. THE
COLD AIR ALOFT AND SYNOPTIC SCALE WEST-NORTHWEST FLOW THROUGH THE
PERIOD WILL KEEP PLENTY OF LAKE-ENHANCED CLOUD COVER AND POTENTIALLY
RAIN SHOWERS IN THE MIX FOR MONDAY AND TUESDAY.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
VFR CONDITIONS WILL CONTINUE ACROSS THE BULK OF THE REGION FOR THIS
AFTERNOON. ONLY LAKE CLOUDS LEFT HAVE RETREATED OVER CENTRAL LAKE
ERIE AND WILL CONTINUE TO BREAK UP THROUGH LATE THIS AFTERNOON.

DAYTIME HEATING HAS BROUGHT ABOUT A DIURNAL CU FIELD AS EXPECTED
ACROSS ALL AREAS JUST INLAND FROM THE LAKES. SOME LOWER-END VFR
DECKS IN THE 4-6KFT RANGE ARE BEING OBSERVED UNDER THE CU FIELD.
SOME MID AND HIGH CLOUDS ARE NOW STARTING TO WORK INTO FAR NORTHERN
PORTIONS OF NEW YORK STATE IN ADVANCE OF AN APPROACHING COLD FRONT.

TONIGHT...THE AFOREMENTIONED COLD FRONT WILL SLOWLY PRESS SOUTHWARD
INTO NEW YORK STATE...BRINGING LOWER-END VFR CIGS AND THE CHANCE OF
A FEW LIGHT SHOWERS TO THE NORTH COUNTRY OVERNIGHT. BY LATE IN THE
NIGHT...SOME OF THE LOWER VFR CIGS WILL MAY PUSH AS FAR SOUTH AS A
KBUF-KROC LINE.

THE COLD FRONT FRONT WILL THEN PUSH SOUTH OF THE REGION TOMORROW
MORNING POSSIBLY BRINGING A FEW LIGHT SCATTERED SHOWERS/SPRINKLES TO
ALL TERMINALS AS IT MOVES THROUGH. A PERIOD OF MVFR CIGS WILL BE A
POSSIBILITY TOMORROW MORNING IN THE MOIST COOL AIRMASS THAT WILL
MOVE IN BEHIND THE FRONT...ESPECIALLY SOUTH OF LAKE ONTARIO AS
COOL...MOIST NORTH TO NORTHEAST FLOW OFF LAKE ONTARIO WILL ADD IN A
NICE UPSLOPE COMPONENT. EXPECT MVFR CIGS TO HANG ON THROUGH THE
MORNING...BEFORE POSSIBLY LIFTING TO AT OR NEAR LOW VFR AT THE VERY
END OF THE PERIOD.

OUTLOOK...
THURSDAY THROUGH SATURDAY...GENERALLY VFR...WITH THE POSSIBLE
EXCEPTION OF SOME POST-FRONTAL MVFR CIGS THURSDAY MORNING. SOME
LOCALIZED IFR SOUTHERN TIER VALLEY FOG WILL ALSO BE POSSIBLE FRIDAY
AND SATURDAY MORNINGS.
SUNDAY...VFR/MVFR WITH SHOWERS BECOMING LIKELY.

&&

.MARINE...
HIGH PRESSURE WILL DRIFT SOUTH OF NEW YORK STATE THIS
AFTERNOON...ALLOWING A WEAK COLD FRONT TO CROSS THE LOWER LAKES
LATER TONIGHT AND THURSDAY MORNING. FOLLOWING THIS FRONT...ANOTHER
AREA OF HIGH PRESSURE WILL BUILD FROM CENTRAL ONTARIO PROVINCE TO
THE NEW ENGLAND COASTLINE THURSDAY THROUGH FRIDAY.

IN THE IMMEDIATE WAKE OF THE COLD FRONT...A BRIEF PERIOD OF
MODERATE NORTHERLIES COULD BRING CONDITIONS CLOSE TO ADVISORY LEVELS
ON EASTERN LAKE ONTARIO VERY LATE TONIGHT AND THURSDAY MORNING.
OTHERWISE...WINDS AND WAVES SHOULD REMAIN BELOW ADVISORY CRITERIA
THROUGH FRIDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING
     FOR NYZ006>008.
MARINE...NONE.

&&

$$

SYNOPSIS...JM/JJR
NEAR TERM...JM/JJR
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...JM/JJR
MARINE...JM/JJR







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