Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 291121
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
721 AM EDT MON SEP 29 2014

.SYNOPSIS...
HIGH PRESSURE WILL MAINTAIN ITS CONTROL OVER THE NORTHEAST TODAY
WITH FAIR WEATHER AND A DECENT AMOUNT OF SUNSHINE THROUGH HIGH LEVEL
CIRRUS. BEHIND A WEAK COLD FRONT AN UPPER LEVEL DISTURBANCE MAY
BRING A FEW SHOWERS ACROSS THE REGION TUESDAY AND TUESDAY NIGHT
BEFORE FAIR WEATHER AND SUNNY SKIES RETURN FOR WEDNESDAY AND
THURSDAY. A STRONG COLD FRONT WILL CROSS THE REGION ON FRIDAY WITH A
GOOD CHANCE OF SHOWERS FOLLOWED BY MUCH COOLER TEMPERATURES FOR NEXT
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS CIRRUS PASSES EASTWARD AND SKIES CLEAR ACROSS WESTERN NEW YORK
FOG HAS EXPANDED ACROSS PORTIONS OF WESTERN NEW YORK. LATEST GOES
LOW CLOUD BASE DEPICTS A BANK OF FOG ALONG THE NORTHERN SHORELINE OF
LAKE ERIE EXPANDING EASTWARD ACROSS PORTIONS OF NORTHERN ERIE AND
NIAGARA COUNTIES. THIS FOG IS FORMING UNDER LIGHT WINDS AND ALSO
WHERE SOME HIGHER DEWPOINTS/GREATER MOISTURE LIES. ALSO VALLEY FOG
IS FILLING THE SOUTHERN TIER RIVER VALLEYS FROM WEST TO EAST AS
LOCATIONS SUCH AS JAMESTOWN HAS FALLEN BELOW HALF A MILE. THIS FOG
WILL DISSIPATE BY MID MORNING AS DAYTIME MIXING OF DRIER AIR ALOFT
INCREASES WITH THE RISING SUN.

AT THE SURFACE THIS MORNING A BROAD AREA OF HIGH PRESSURE REMAINS
ACROSS THE EASTERN US...CENTERED NOW ACROSS THE SOUTHEAST. A WEAK
COLD FRONT IS DROPPING SOUTHWARD FROM CANADA AND ACROSS THE LAKE
ONTARIO AND NORTH COUNTRY REGION. WATER VAPOR IMAGERY DISPLAYS A
WEAK UPPER LEVEL DISTURBANCE NEARING THE WESTERN END OF LAKE ERIE
THIS MORNING.

FOR TODAY THIS MOISTURE STARVED COOL FRONT WILL CONTINUE TO DROP
SOUTHWARD ACROSS THE CWA...LIKELY STALLING SOMEWHERE JUST SOUTH OF
LAKE ONTARIO. LITTLE MOISTURE ALONG THIS FRONT WILL CONTINUE THE DRY
STREAK WITH JUST CIRRUS PASSING ACROSS THE REGION AHEAD OF THE UPPER
LEVEL LOW. SKIES WILL LIKELY BE FILLED WITH CIRRUS THROUGH THE
MORNING WITH SOME CLEARING THIS AFTERNOON AS THE WEAK UPPER LEVEL
DISTURBANCE CARRIES EASTWARD. THIS MOISTURE STARVED COLD FRONT MAY
PRODUCE A FEW MID LEVEL CLOUDS SOUTH OF LAKE ONTARIO AS IT PASSES
THROUGH. OTHERWISE SUNSHINE THROUGH THIS CIRRUS ALONG WITH 850 HPA
TEMPERATURES AROUND 12C/AND 925 HPA AROUND 18 TO 20C...COUPLED WITH
A STILL DRY AIRMASS AND DRY GROUND WILL BRING SURFACE HIGHS INTO THE
MID AND UPPER 70S. THOUGH THESE VALUES WILL BE SIMILAR TO RECENT
DAYS THE SUNLIGHT SHOULD BE MORE FILTERED TODAY SUCH THAT OUR
AFTERNOON HIGHS FALL JUST A DEGREE OR SO COOLER THAN SUNDAY. THESE
READINGS WILL STILL BE SOME 10 DEGREES OR MORE ABOVE LATE SEPTEMBER
NORMS.

TONIGHT CLOUDS WILL THICKEN AHEAD OF A STRONGER UPPER LEVEL
SHORTWAVE...ONE THAT WILL CROSS THE GREAT LAKES REGION OVERNIGHT.
RAIN SHOWERS WITH THIS FEATURE WILL LIKELY REMAIN JUST TO OUR WEST
THROUGH THE NIGHT LEAVING OUR AREA DRY WITH OVERNIGHT LOWS
MILD...GENERALLY IN THE MID TO UPPER 50S. WITH THE INCREASE IN
CLOUDS OVERNIGHT FOG FORMATION EVEN IN THE SOUTHERN TIER VALLEYS
SHOULD BE VERY LIMITED TO NON EXISTENT.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A CLOSED 500 MB LOW AND WEAK SURFACE REFLECTION WILL TRACK FROM LAKE
HURON TO EASTERN LAKE ERIE BY 00Z WEDNESDAY. TRACKING FROM CENTRAL
CANADA THERE IS LIMITED MOISTURE WITH THIS SYSTEM AND IT WILL
STRUGGLE TO TAP INTO ANY MARITIME MOISTURE WHEN IT REACHES OUR
REGION. HOWEVER...A WEAK FRONTAL BOUNDARY ALONG THE LEADING EDGE OF
THE SHORTWAVE MAY BRING SOME LIGHT PRECIPITATION TO FAR WESTERN
PORTIONS ON TUESDAY MORNING. THEN TUESDAY AFTERNOON THE SHORTWAVE
WILL MOVE ACROSS AN AREA OF SURFACE CONVERGENCE ACROSS CENTRAL NY.
HIGH RES GUIDANCE SUCH AS THE NAM HAS BEEN FAIRLY CONSISTENT IN
DEVELOPING SHOWERS ALONG THIS SUBTLE BOUNDARY TUESDAY
AFTERNOON...WITH THE 00Z RGEM/NAM RUNS ADDING TO FORECAST
CONFIDENCE. EXPECT AN AREA OF SLOW MOVING SHOWERS TO DEVELOP NEAR A
WELLSVILLE TO SYRACUSE LINE ON TUESDAY AFTERNOON. 00Z NAM/GFS SHOW
MODEST CAPES AVERAGING AROUND 500 J/KG IN THIS AREA WHICH SUGGESTS A
LIMITED POTENTIAL FOR THUNDERSTORMS. THIS WILL LARGELY DEPEND ON HOW
MUCH SUNSHINE THIS AREA GETS EARLIER IN THE DAY.

SHOWERS WILL LINGER NEAR THIS BOUNDARY INTO THE EVENING HOURS BUT
SHOULD TAPER OFF LATE TUESDAY NIGHT AS THE UPPER LEVEL AND SURFACE
LOW EXIT INTO EASTERN PENNSYLVANIA. NAM BUFKIT PROFILES HINTS THAT
LOW LEVEL MOISTURE WILL BE TRAPPED IN THE LOW LEVELS...WHICH WILL
LIKELY RESULT IN LOW CLOUDS SOUTH OF LAKE ONTARIO WHICH WILL BE
ENHANCED BY A NORTHEAST UPSLOPE FLOW.

HIGH PRESSURE GRADUALLY BUILDS BACK INTO THE REGION WEDNESDAY...THEN
RIDGES INTO OUR REGION WITH MORE AUTHORITY WEDNESDAY NIGHT. A WIDELY
SCATTERED SHOWER CAN/T BE RULED OUT WEDNESDAY ACROSS THE GENESEE
VALLEY AND FINGER LAKES REGIONS...BUT ALL AREAS SHOULD BE DRY AND
MOSTLY CLEAR BY WEDNESDAY NIGHT.

TEMPERATURES WILL BE NOTABLY COOLER THAN THEY HAVE BEEN...BUT STILL
A BIT ABOVE NORMAL FOR THIS TIME OF YEAR. HIGHS ON TUESDAY AND
WEDNESDAY SHOULD BE IN THE UPPER 60S TO LOWER 70S...WITH OVERNIGHT
LOWS IN THE 50S.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
THURSDAY WILL BE THE NICEST DAY OF THIS PERIOD AS AN UPPER RIDGE
CRESTS ACROSS THE AREA...WHILE STRONG CANADIAN SURFACE HIGH PRESSURE
NOSES SOUTHWARD ACROSS NEW YORK STATE...WHICH WILL KEEP CONDITIONS
DRY ACROSS THE AREA. AS THE SURFACE HIGH SHIFTS EAST...WINDS WILL
BECOME MORE SOUTHEASTERLY. THIS COMBINED WITH STRONG SUBSIDENCE
ALOFT WILL HELP BOOST TEMPS INTO THE 70S. THE UPPER RIDGE AND
SURFACE HIGH PRESSURE WILL SHIFT EAST OF THE AREA THURSDAY
NIGHT...AS A SIGNIFICANT UPPER LEVEL TROUGH BEGINS TO APPROACH THE
REGION FROM THE UPPER GREAT LAKES. TEMPERATURES WILL REMAIN ON THE
WARM SIDE...WITH SSE WINDS RESULTING IN DOWNSLOPE WARMING.

A CONSENSUS OF THE 00Z GGEM/GFS/ECMWF ARE IN PRETTY GOOD AGREEMENT
WITH 12Z RUNS. THUS THERE IS LITTLE CHANGE IN TIMING...BUT GIVEN RUN
TO RUN CONSISTENCY HAVE UPPED POPS TO THE LIKELY CATEGORY. MODEL
GUIDANCE TAKES A SURFACE LOW FROM THE VICINITY OF THE UPPER LAKES
FRIDAY...ALMOST DUE NORTH NORTHEAST TO JAMES BAY BY EARLY SATURDAY
WITH A CONSENSUS FROPA TIMING FRIDAY AFTERNOON AND EVENING. IT WILL
BE QUITE WINDY BOTH AHEAD OF AND BEHIND THE FRONT...AS OUR WEATHER
PATTERN TRANSITIONS TO A COOL SEASON ONE.

CLOUDS AND SHOWERS WILL MOVE FROM WEST TO EAST ON FRIDAY...WHICH
WILL COMPLICATE TEMPERATURES A BIT. HIGHS WILL DEPEND ON THE TIMING
OF THE FRONT...WITH THE WARMEST TEMPERATURES TO THE EAST WITH THE
LATER FROPA. HIGHS SHOULD RANGE FROM THE UPPER 60S TO MID 70S...WITH
GUSTY SOUTHWEST WINDS BEHIND THE FRONT USHERING IN MUCH COOLER AIR
THROUGH FRIDAY NIGHT.

A HIGHLY AMPLIFIED UPPER TROUGH WILL BUILD INTO THE NORTHEAST FOR
THE REMAINDER OF THE UPCOMING WEEKEND...ALONG WITH MUCH COOLER AIR.
A STRONG SHORTWAVE WILL ROTATE THROUGH THE BASE OF THE DEEP LONGWAVE
TROUGH LATER SATURDAY INTO SUNDAY. THIS COMBINED WITH WRAP AROUND
MOISTURE ON THE BACK SIDE OF THE LOW WILL KEEP THE THREAT OF AT
LEAST SOME SCATTERED SHOWERS AROUND DURING THIS TIMEFRAME. IT ALSO
WILL BE COLD ENOUGH ALOFT FOR SOME LAKE EFFECT RAIN SHOWERS EAST OF
THE LAKES SATURDAY NIGHT INTO SUNDAY. 850MB TEMPS WILL FALL TO
AROUND 0C TO -2C...WILL MAKE IT TOUGH FOR HIGH TEMPS TO GET OUT OF
THE 50S ON SUNDAY ACROSS THE AREA...WHILE LOWS SATURDAY NIGHT FALL
BACK INTO THE 40S.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AT 12Z SEVERAL AREAS OF FOG HAVE REDUCED VSBYS TO LIFR THIS MORNING.
TRADITIONAL VALLEY FOG ACROSS THE WESTERN SOUTHERN TIER AS WELL AS A
BANK OF FOG OVER THE NIAGARA RIVER AND TOWARDS NIAGARA FALLS ARE
REDUCING VSBYS TO LESS THAN A HALF MILE. WITH DAYTIME MIXING ALL
SITES SHOULD RETURN TO VFR BETWEEN 13 AND 15Z THIS MORNING.

THERE WILL BE SOME PASSING CIRRUS OVERHEAD THROUGH THE DAY WITH SOME
MID LEVEL CLOUDS INLAND AWAY FROM THE LAKES BUT VFR FLIGHT
CONDITIONS SHOULD PREVAIL. CLOUDS SHOULD THICKEN THROUGH THE NIGHT
TONIGHT AHEAD OF AN UPPER LEVEL DISTURBANCE SUCH THAT VALLEY FOG
SHOULD BE VERY LIMITED THROUGH THE NIGHT. RAIN SHOWERS WILL REACH
FAR WESTERN NEW YORK AROUND 12Z TOMORROW. FOR NOW WILL NOT MENTION
ANY SHOWERS WITH THIS 12Z TAF PACKAGE.

OUTLOOK...
TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS. IFR CIGS POSSIBLE
SOUTH OF LAKE ONTARIO TUESDAY NIGHT AND INTO WEDNESDAY MORNING.
WEDNESDAY THROUGH THURSDAY...VFR EXCEPT FOR SOUTHERN TIER VALLEY FOG
WITH LOCAL IFR EACH LATE NIGHT AND EARLY MORNING.
FRIDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
ALTHOUGH AN AREA OF HIGH PRESSURE WILL SLIP SOUTHWARD...IT WILL
STILL INFLUENCE THE EASTERN GREAT LAKES REGION WITH LIGHT WINDS AND
MINIMAL WAVES THROUGH TUESDAY. BEHIND AN UPPER LEVEL DISTURBANCE
SLIGHTLY COOLER AIR WILL FLOW OVER THE LAKES TUESDAY NIGHT AND WITH
A NORTHEAST WIND DIRECTION FROM A STRONG AREA OF HIGH PRESSURE OVER
QUEBEC WAVES WILL INCREASE TO AROUND 2 TO 3 FEET ON LAKE ONTARIO. ON
LAKE ERIE WAVES WILL REMAIN AROUND 1 FOOT ON THE EASTERN WATERS.

HIGH PRESSURE WILL AGAIN RETURN TO THE EASTERN GREAT LAKES WEDNESDAY
AND THURSDAY WITH LIGHT WINDS AND MINIMAL WAVES.

A STRONG AREA OF LOW PRESSURE WILL MOVE INTO THE EASTERN GREAT LAKES
REGION BY FRIDAY... PRODUCING A PERIOD OF STRONGER WINDS ACROSS THE
LOWER LAKES WITH SMALL CRAFT CONDITIONS POSSIBLE.

&&

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

&&

$$

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







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