Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 180753
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
353 AM EDT MON AUG 18 2014

.SYNOPSIS...
HIGH PRESSURE OVER THE UPPER GREAT LAKES WILL PASS BY TO OUR
NORTH...AND THIS WILL KEEP FAIR WEATHER IN PLACE OVER OUR REGION. A
WARM FRONT WILL THEN PUSH NORTH FROM THE OHIO VALLEY ON TUESDAY...
AND THIS WILL USHER IN A RETURN TO MORE SEASONABLE TEMPERATURES
ALONG WITH SOME SHOWERS AND THUNDERSTORMS. THE MOST UNSETTLED PERIOD
WILL BE WEDNESDAY AND THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
WHILE HIGH PRESSURE OVER THE UPPER GREAT LAKES WILL BRING THE
PROMISE OF FAIR DRY WEATHER TO OUR REGION...WE WILL HAVE TO DEAL
WITH SOME STUBBORN CLOUD COVER DURING THE REMAINDER OF THE EARLY
MORNING HOURS.

A FAIR AMOUNT OF LOW LEVEL MOISTURE...CAPPED BENEATH A STRONG
SUBSIDENCE INVERSION AT 6K FT...IS BEING OROGRAPHICALLY LIFTED BY A
LIGHT NORTHERLY WIND. THIS IS PRODUCING PARTLY TO MOSTLY CLOUDY
SKIES ACROSS A LARGE PORTION OF OUR FORECAST AREA...BUT THE LIFT IS
NOT SIGNIFICANT ENOUGH TO GENERATE ANY PCPN. THIS GENERAL SCENARIO
WILL REMAIN IN PLACE THROUGH THE INITIAL DAYLIGHT HOURS...AFTER
WHICH TIME DRIER MID LEVEL AIR WILL DIURNALLY MIX WITH THE LOWER
LEVELS WHILE THE LOW LEVEL FLOW WILL TEMPORARILY BACK TO THE
NORTHWEST. THIS SHOULD PROMOTE INCREASING AMOUNTS OF SUNSHINE AND
HELP TO SEND AFTERNOON TEMPERATURES INTO THE LOW TO MID 70S. THE
COOLEST AREA WILL BE EAST OF LK ONTARIO WHERE TEMPS WILL STRUGGLE TO
GET OUT OF THE 60S.

THE UPCOMING NIGHT SHOULD THEN FEATURE STARLIT SKIES AS THE AREA OF
HIGH PRESSURE WILL DRIFT TO THE EAST ACROSS QUEBEC AND THE SAINT
LAWRENCE VALLEY. TEMPERATURES TONIGHT WILL DROP INTO THE 50S ACROSS
THE WESTERN COUNTIES...AND INTO THE 40S EAST OF LAKE ONTARIO.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
ON TUESDAY...SURFACE HIGH PRESSURE CENTERED OVER EASTERN NEW YORK AT
THE START OF THE DAY WILL SLIDE OUT INTO NEW ENGLAND...WHILE THE
NEXT NOTEWORTHY MID LEVEL TROUGH AND ASSOCIATED BROAD SURFACE LOW
PUSHES INTO THE WESTERN AND CENTRAL GREAT LAKES. WHILE THIS SYSTEM
WILL REMAIN FAR ENOUGH TO OUR WEST FOR THE BULK OF OUR AREA TO ENJOY
ONE MORE DRY DAY...A WEAK SOUTHERLY RETURN FLOW DEVELOPING ACROSS
PENNSYLVANIA AND SOUTHERN NEW YORK WILL HELP TO INCREASE LOW
LEVEL MOISTURE ACROSS THE SOUTHERN TIER AND INTERIOR SECTIONS OF
FINGER LAKES. COUPLED WITH DIURNAL HEATING...THIS MAY LEAD TO THE
DEVELOPMENT OF SOME SCATTERED SHOWERS/THUNDERSTORMS IN THESE AREAS
DURING THE AFTERNOON...BEFORE THESE SLIDE EASTWARD AND GRADUALLY
FADE OUT WITH THE LOSS OF HEATING TUESDAY EVENING.

AFTER THAT...CONDITIONS SHOULD STEADILY TREND DOWNHILL THROUGH
WEDNESDAY NIGHT AS THE MID LEVEL TROUGH AND SURFACE LOW TRACK INTO
THE LOWER GREAT LAKES...WHILE GRADUALLY PUSHING THEIR ATTENDANT WARM
FRONT INTO NEW YORK STATE FROM THE OHIO VALLEY. BURGEONING
MOISTURE...LIFT...AND INSTABILITY ASSOCIATED WITH THE ENCROACHING
WARM FRONT WILL RESULT IN AN INCREASING RISK FOR SHOWERS AND
SCATTERED EMBEDDED THUNDERSTORMS OVER TIME...WITH THESE BEGINNING AS
EARLY AS TUESDAY EVENING ACROSS FAR SOUTHWESTERN NEW YORK...BEFORE
SPREADING NORTHEASTWARD ACROSS THE REMAINDER OF THE REGION THROUGH
THE REMAINDER OF TUESDAY NIGHT AND WEDNESDAY. AT THIS POINT...BOTH
AVAILABLE MOISTURE AND SYNOPTIC-SCALE SUPPORT APPEAR TO BE PLENTY
SUFFICIENT FOR BUMPING POPS UP TO LIKELY IN ASSOCIATION WITH THE
WARM FRONT...WITH THE CONVECTION PROBABLY THEN TRENDING A LITTLE
MORE SCATTERED IN ITS WAKE WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT.

THURSDAY AND THURSDAY NIGHT...UNSETTLED WEATHER SHOULD CONTINUE AS
THE BAGGY MID LEVEL TROUGH LINGERS ACROSS THE LOWER LAKES REGION AND
NORTHEAST...WHILE ITS ATTENDANT WEAK SURFACE LOW/FRONTAL BOUNDARY
STALLS OUT ACROSS NEW YORK STATE...AND PROVIDES THE FOCUS FOR AT
LEAST SOME MORE SCATTERED SHOWERS AND THUNDERSTORMS. AT THIS POINT
IT APPEARS THAT THESE WOULD BE MOSTLY LIKELY TO REACH THEIR GREATEST
AREAL COVERAGE IN CONJUNCTION WITH PEAK DIURNAL HEATING THURSDAY
AFTERNOON...BEFORE FADING SOME WITH NOCTURNAL STABILIZATION THURSDAY
NIGHT.

WITH RESPECT TO TEMPERATURES...THESE WILL GENERALLY AVERAGE OUT
RIGHT AROUND MID-AUGUST NORMALS THROUGH THE PERIOD DUE TO THE
APPROACH OF THE WARM FRONT AND ATTENDANT WARMING OF OUR AIRMASS.
MORE SPECIFICALLY...HIGHS WILL RANGE IN THE MID 70 TO LOWER 80S EACH
DAY...WHILE NIGHTTIME LOWS AVERAGE OUT IN THE UPPER 50S TO MID 60S.
THE WARMING TREND WILL ALSO BE ACCOMPANIED BY A NOTICEABLE INCREASE
IN HUMIDITY LEVELS...WITH DEWPOINTS GRADUALLY CLIMBING BACK TO AT
LEAST THE LOWER TO MID 60S BY LATER WEDNESDAY...THEN LINGERING IN
THIS GENERAL VICINITY RIGHT THROUGH THE END OF THE PERIOD.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
IN THE EXTENDED PORTION OF THE FORECAST...THE MEDIUM RANGE GUIDANCE
IS IN DECENT AGREEMENT THAT MID LEVEL TROUGHING LINGERING OVER OUR
REGION AT THE START OF THE PERIOD WILL GRADUALLY GET SHUNTED OFF TO
OUR SOUTH AND EAST AS STRENGTHENING RIDGING DEVELOPS OVER EASTERN
CANADA...THEN MERGES WITH A LARGER AND MORE DOMINANT UPPER LEVEL
RIDGE SLOWLY NOSING NORTHEASTWARD FROM THE SOUTHERN PLAINS STATES.

WHILE THE VARIOUS GUIDANCE PACKAGES STILL DIFFER WITH REGARD TO HOW
EXACTLY HOW QUICKLY ALL OF THIS TAKES PLACE...IN GENERAL THIS SHOULD
RESULT IN IMPROVING CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NEW
YORK AS THE AFOREMENTIONED TROUGH GETS SHOVED OFF TO OUR SOUTH AND
EAST...AND PROGRESSIVELY DRIER AND MORE STABLE AIR BUILDS
SOUTHWESTWARD ACROSS OUR REGION. FOLLOWING A ROUGH BLEND OF THE 00Z
GFS/ECMWF SOLUTIONS AS A GUIDE FOR THIS PERIOD...WE CAN EXPECT
GRADUALLY DIMINISHING CHANCES OF SCATTERED SHOWERS AND THUNDERSTORMS
FRIDAY THROUGH SATURDAY...WITH MAINLY DRY WEATHER THEN LIKELY
RETURNING BY NEXT SUNDAY.

AS FOR TEMPS...WITH LITTLE NOTEWORTHY WARMING OR COOLING OF OUR
AIRMASS EXPECTED...THESE SHOULD REMAIN NEAR SEASONAL NORMS RIGHT
OUT THROUGH THE END OF THE PERIOD...WITH DAYTIME HIGHS AVERAGING OUT
IN THE MID 70S TO LOWER 80S...AND NIGHTTIME LOWS RANGING FROM THE
UPPER 50S TO MID 60S.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
A LIGHT NORTHERLY UPSLOPE FLOW WILL PRODUCE A FAIR AMOUNT OF VFR
STRATO-CU DURING THE REMAINING OVERNIGHT HOURS. THE ONLY AREA OF
CONCERN WILL BE ACROSS PARTS OF THE SRN TIER WHERE CLEAR SKIES
EARLIER INT HE NIGHT HAVE ALREADY LED TO AREAS OF DENSE FOG AND/OR
PATCHES OF LOW STRATUS. THIS IFR WX WILL MAINLY BE AN ISSUE FOR
KJHW AND KELZ.

AS WE PROGRESS THROUGH THE FIRST HALF OF THIS MORNING...ANY IFR/MVFR
CONDITIONS WILL QUICKLY IMPROVE TO VFR...WITH SKIES ATTEMPTING TO
TOTALLY CLEAR DURING THE AFTERNOON.

HIGH PRESSURE OVER QUEBEC TONIGHT WILL THEN SUPPLY THE REGION WITH
VFR CONDITIONS INTO TUESDAY.

OUTLOOK...
TUESDAY...VFR.
WEDNESDAY THROUGH FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND
THUNDERSTORMS.

&&

.MARINE...
HIGH PRESSURE CENTERED NORTH OF GEORGIAN BAY EARLY THIS MORNING WILL
DRIFT ACROSS TO THE NORTH OF LAKE ONTARIO DURING THE COURSE OF TODAY
BEFORE MAKING ITS WAY ACROSS QUEBEC AND THE ST LAWRENCE VALLEY
TONIGHT. THE RESULTING WEAK SFC PRESSURE GRADIENT WILL PROMOTE LIGHT
WINDS AND NEGLIGIBLE WAVES ACROSS LAKES ERIE AND ONTARIO.

AS THE SFC HIGH MOVES FURTHER EAST AND A WEAK AREA OF LOW PRESSURE
ADVANCES FROM WISCONSIN...EAST TO NORTHEAST WINDS WILL FRESHEN
ACROSS THE LOWER LAKES (ESP. LAKE ONTARIO). THIS WILL LIKELY PRODUCE
SOME CHOPPY CONDITIONS OVER WESTERN LAKE ONTARIO...ALTHOUGH WINDS
AND WAVES WILL REMAIN BELOW SCA ADVISORY CRITERIA.

WHILE WINDS AND WAVES WILL REMAIN BELOW SCA LEVELS TUESDAY NIGHT AND
WEDNESDAY...IT WILL BECOME UNSETTLED WITH THE LIKELIHOOD OF SHOWERS
AND THUNDERSTORMS.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH







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