Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 211101
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
701 AM EDT SUN SEP 21 2014

.SYNOPSIS...
OCCASIONAL SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL ACCOMPANY A
COLD FRONT AS IT CROSSES THE AREA TODAY...WITH MUCH COOLER WEATHER
RETURNING FOR TONIGHT AND MONDAY IN ITS WAKE. EXPANSIVE HIGH
PRESSURE WILL THEN BUILD ACROSS THE AREA THROUGH THE REMAINDER OF
THE WEEK AND PROVIDE WESTERN AND NORTH CENTRAL NEW YORK WITH AN
EXTENDED PERIOD OF FINE EARLY FALL WEATHER...ALONG WITH SLOWLY
WARMING TEMPERATURES.

&&

.NEAR TERM /THROUGH TONIGHT/...
DURING THE NEAR TERM PERIOD...COMPLEX LOW PRESSURE DRAPED FROM
WESTERN QUEBEC TO THE CENTRAL GREAT LAKES WILL LIFT STEADILY
NORTHEASTWARD AND EVENTUALLY CONSOLIDATE OVER THE CANADIAN
MARITIMES. IN THE PROCESS...THIS SYSTEM WILL PUSH ITS ASSOCIATED
COLD FRONT ACROSS WESTERN AND NORTH CENTRAL NEW YORK THIS
AFTERNOON.

THROUGH THE COURSE OF THIS MORNING...OCCASIONAL SHOWERS SHOULD
CONTINUE TO BLOSSOM AND SPREAD NORTHEASTWARD ACROSS THE AREA AS A
STRONG SHORTWAVE DIGS ACROSS THE CENTRAL GREAT LAKES. GIVEN ONLY
VERY LIMITED INSTABILITY...AT THIS POINT EXPECT ANY THUNDERSTORMS TO
REMAIN ISOLATED TO SCATTERED IN COVERAGE...AND NOT PARTICULARLY
STRONG IN NATURE EVEN IN SPITE OF IMPRESSIVE AMOUNTS OF SHEAR.

BY MIDDAY/EARLY THIS AFTERNOON...MUCH DRIER AIR WILL BEGIN SPREADING
ACROSS THE AREA ALOFT. THIS SHOULD RESULT IN THE PRECIPITATION
COVERAGE DIMINISHING FROM WEST TO EAST ALONG WITH THE RETURN OF SOME
PARTIAL SUNSHINE...THOUGH SOME ADDITIONAL SCATTERED CONVECTION STILL
CANNOT BE TOTALLY RULED OUT THROUGH THE BALANCE OF THE DAY GIVEN
THAT WE`LL STILL HAVE TO DEAL WITH THE PASSAGE OF THE TRAILING COLD
FRONT AND THE APPROACH OF THE MAIN UPPER LEVEL TROUGH AXIS. AT THIS
POINT...HAVE REFLECTED THIS TREND IN THE FORECAST WITH A REDUCTION
IN POPS FROM CATEGORICAL TO THE CHANCE RANGE.

TONIGHT...THE CORE OF THE UPPER LEVEL TROUGH WILL SLIDE EASTWARD
ACROSS THE AREA...ALONG WITH A SECONDARY AREA OF WRAPAROUND
MOISTURE. THIS FEATURE SHOULD PRODUCE AN ADDITIONAL ROUND OF
SCATTERED SHOWERS AS IT MOVES THROUGH...WITH THESE PERHAPS BEING
AIDED BY A DEVELOPING NORTHWESTERLY /UPSLOPE/ LOW LEVEL FLOW OFF
THE LOWER GREAT LAKES. EXPECT THE BULK OF THESE TO COME BEFORE
06Z...WITH A GRADUAL SHRINKING IN COVERAGE THEN EXPECTED OVERNIGHT.
OTHERWISE...EXPECT A FAIR AMOUNT OF LOW CLOUDS TO DEVELOP AREAWIDE
DUE TO THE DEVELOPING UPSLOPE FLOW AND INCREASING LOW LEVEL
MOISTURE.

WITH RESPECT TO TEMPERATURES...TODAY`S HIGHS SHOULD AVERAGE ABOVE
NORMAL GIVEN THE SEASONABLY MILD AIRMASS THAT WILL BE IN PLACE AHEAD
OF THE COLD FRONT...WITH MOST AREAS SEEING HIGHS BETWEEN 70 AND 75
DEGREES. UNDER STRONG COOL AIR ADVECTION...READINGS WILL THEN COOL
BACK TO MORE TYPICAL LEVELS IN THE UPPER 40S AND LOWER 50S TONIGHT.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
BROAD RIDGING WILL DOMINATE THE NORTH AMERICAN CONTINENT DURING THIS
TIME FRAME...WITH THE CONCENTRATION OF GREATEST HGT ANOMALIES
TRACKING FROM THE FOOT OF THE CANADIAN ROCKIES EASTWARD ACROSS THE
CANADIAN PRAIRIES TO THE GREAT LAKES REGION. THIS PATTERN WILL BE
REPRESENTED AT THE SFC BY EXPANSIVE HIGH PRESSURE THAT WILL
MONOPOLIZE THE WEATHER OVER MUCH OF THE EASTERN CONUS. WHILE IT WILL
BE RELATIVELY COOL TO START THE PERIOD...THE EASTWARD PROGRESSION OF
THE AFOREMENTIONED SYNOPTIC PATTERN WILL PROMOTE A GRADUAL DAY TO
DAY TO WARMING TREND THAT WILL SEND THE MERCURY TO ABOVE NORMAL
LEVELS BY MID WEEK.

BREAKING THIS DOWN INTO SOME DETAIL...
A LONGWAVE TROUGH EXTENDING FROM QUEBEC AND THE ST LAWRENCE VALLEY
SOUTHWARDS ACROSS THE LOWER GREAT LAKES AND TENNESSEE VALLEY MONDAY
MORNING WILL PUSH EAST DURING THE COURSE OF THE DAY...WHILE THE
IMPRESSIVE WESTERN CONUS BASED RIDGE WILL MOVE ACROSS THE PLAINS.
PLENTY OF MID LEVEL DRY AIR WILL WORK ACROSS OUR REGION IN THE
IMMEDIATE WAKE OF THE TROUGH...YET A WEALTH OF LOW LEVEL MOISTURE
WILL PERSIST. RELATIVELY LIGHT WINDS BELOW 5K FT WILL HAVE A TOUGH
TIME CLEARING OUT THE ASSOCIATED CLOUD COVER...SO THE BULK OF THE
DAY SHOULD BE MOSTLY CLOUDY. THIS WILL ONLY EMPHASIZE THE CHANGE TO
MUCH COOLER WEATHER FROM THE WEEKEND. H85 TEMPS WILL BOTTOM OUT
CLOSE TO ZERO C MONDAY AFTERNOON...WITH A LACK OF SUNSHINE ENSURING
THAT NEAR SFC TEMPS WILL NOT CLIMB OUT OF THE 50S F. THIS WILL BE A
CHANGE OF SOME 20 DEGREES FROM EARLIER IN THE WEEKEND.

WHILE THE LAYER OF LOW LEVEL MOISTURE WILL THIN MONDAY NIGHT...A
STRENGTHENING SUBSIDENCE INVERSION FROM APPROACHING STRONG HIGH
PRESSURE OVER THE OHIO VALLEY SHOULD KEEP ENOUGH CLOUD COVER TRAPPED
TO KEEP SKIES AT LEAST PARTLY...IF NOT MOSTLY CLOUDY. A CYCLONIC
FLOW ABV H925 WILL NOT HELP MATTERS EITHER. WILL INCREASE SKY COVER
FROM CONTINUITY TO ACCOUNT FOR THIS SCENARIO.

ON TUESDAY...THE CENTER OF THE SFC HIGH IS FORECAST TO CROSS
DIRECTLY OVER THE LOWER GREAT LAKES. THIS WILL INCREASE THE DEPTH OF
AN ALREADY ON GOING WARM ADVECTION PROCESS...WHICH WILL NOT ONLY
LEAD TO A MUCH MILDER DAY...BUT WILL LIKELY GENERATE A FAIR AMOUNT
OF ALTO-CU. IN ANY CASE...WE SHOULD BE ABLE TO EXPERIENCE A LITTLE
SUNSHINE WITH H85 TEMPS INCREASING TO ARND 8C SUPPORTING AFTERNOON
MAX TEMPS IN THE MID 60S F.

THE HEART OF THE STRONG SFC HIGH WILL DRIFT ACROSS NEW ENGLAND
TUESDAY NIGHT....THEN WILL BECOME ANCHORED IN THE VCNTY OF NOVA
SCOTIA ON WEDNESDAY. HOW STRONG WILL THE SFC HIGH BE? FORECAST MSLP
VALUES OF 1036-37MB WILL TRANSLATE TO LEVELS THAT ARE ONLY
EXPERIENCED IN THAT AREA/AT THAT TIME OF YEAR TO A ONCE IN 30 YEAR
RETURN INTERVAL. IN ANY CASE...THIS WILL PUT THE BRAKES ON THE WARM
ADVECTION. H85 TEMPS WILL BE HELD AROUND 10C...SO WE CAN ANTICIPATE
WEDNESDAY AFTERNOON HIGHS CLOSE TO 70 ALONG WITH A FAIR AMOUNT OF
SUN.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
SIMPLY PUT...THE EXTENDED PERIOD OF DRY WEATHER WILL CONTINUE INTO
(AND LIKELY THROUGH) NEXT WEEKEND WHILE TEMPERATURES WILL AVERAGE
ABOVE LATE SEPTEMBER NORMALS.

STRONG CONSENSUS EXISTS BETWEEN THE ECMWF AND GFS BASED ENSEMBLES
THAT ANOMALOUSLY STRONG RIDGING WILL REIGN ACROSS EASTERN CANADA AND
THE GREAT LAKES REGION. AGAIN...THE STRENGTH OF THIS PARTICULAR
RIDGE IN ITS FORECAST LOCATION WILL RIVAL THOSE FROM THE PAST 30
YEARS. ITS SFC REFLECTION WILL BE THAT OF A SPRAWLING AREA OF HIGH
PRESSURE THAT WILL BE CENTERED IN THE VCNTY OF THE LOWER GREAT
LAKES.

THE RESULT OF THIS WILL BE A PERIOD OF DRY COMFORTABLE WEATHER WITH
H85 TEMPS ARND 12C SUPPORTING AFTERNOON HIGHS THAT WILL GENERALLY
RANGE FROM 70 TO 75...WHILE OVERNIGHT LOWS WILL BE WITHIN A FEW
DEGREES OF 50 (40S SRN TIER AND NORTH COUNTRY).

LOOKING FURTHER AHEAD...THE RIDGE IS NOT EXPECTED TO BREAK DOWN
UNTIL THE END OF NEXT WEEKEND WITH DRY WEATHER PERSISTING INTO AT
LEAST THE START OF NEXT WORK WEEK.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
DURING THE TAF PERIOD...COMPLEX LOW PRESSURE DRAPED FROM WESTERN
QUEBEC TO THE CENTRAL GREAT LAKES WILL LIFT STEADILY NORTHEASTWARD
AND EVENTUALLY CONSOLIDATE OVER THE CANADIAN MARITIMES. IN THE
PROCESS...THIS SYSTEM WILL PUSH ITS ASSOCIATED COLD FRONT ACROSS
WESTERN AND NORTH CENTRAL NEW YORK SUNDAY AFTERNOON.

EXPECT OCCASIONAL SHOWERS TO DEVELOP AND WORK ACROSS THE REGION
THROUGH THE COURSE THIS MORNING. WHILE THERE WILL ALSO BE A CHANCE
FOR A FEW THUNDERSTORMS AS WELL...THESE SHOULD REMAIN LIMITED IN
COVERAGE. THE SHOWERS WILL THEN GRADUALLY DIMINISH FROM WEST TO EAST
THIS AFTERNOON AND TONIGHT FOLLOWING THE PASSAGE OF THE COLD
FRONT...AND THE TRAILING PARENT UPPER LEVEL TROUGH AXIS.

IN TERMS OF FLIGHT CONDITIONS...EXPECT CIGS TO LOWER TO THE
MVFR/LOWER VFR RANGE TODAY...WITH LOCALIZED LOWER CONDITIONS
POSSIBLE WITHIN ANY SHOWERS. IN THE WAKE OF THE FRONT...A
DEVELOPING NORTHWESTERLY UPSLOPE FLOW OF COOL/MOIST AIR WILL THEN
LEAD TO THE DEVELOPMENT OF FAIRLY WIDESPREAD IFR/MVFR CIGS TONIGHT.

OUTLOOK...
MONDAY...LINGERING SCATTERED SHOWERS ENDING...WITH IFR/MVFR CIGS
GRADUALLY IMPROVING TO VFR.
TUESDAY THROUGH THURSDAY...VFR...EXCEPT FOR LOCALIZED IFR IN
SOUTHERN TIER VALLEY FOG EACH OVERNIGHT/EARLY MORNING.

&&

.MARINE...
IN ADVANCE OF A COLD FRONT...MODERATE SOUTH-SOUTHWESTERLY WINDS WILL
CONTINUE TO PRODUCE ADVISORY-WORTHY CONDITIONS ACROSS THE FAR
EASTERN PORTION OF LAKE ONTARIO...BEFORE CONDITIONS IMPROVE BY
LATER ON THIS MORNING.

OTHERWISE...A COLD FRONT WILL GRADUALLY PUSH ACROSS THE LOWER GREAT
LAKES TODAY. WHILE A WEAKER SURFACE PRESSURE GRADIENT WILL ENCOURAGE
LOWER WINDS AND WAVES...IT WILL BE UNSETTLED WITH OCCASIONAL SHOWERS
AND POSSIBLY A THUNDERSTORM OR TWO.

IN THE WAKE OF THE FRONT...THE COMBINATION OF STRONG COOL AIR
ADVECTION AND A STRENGTHENING NORTHWESTERLY LOW LEVEL FLOW WILL LEAD
TO A RETURN OF ADVISORY-LEVEL WINDS AND WAVES ALONG THE SOUTH SHORE
OF LAKE ONTARIO TONIGHT AND MONDAY. WHILE THE SAME MAY ALSO
ULTIMATELY BE TRUE FOR LAKE ERIE...CONDITIONS THERE CURRENTLY APPEAR
MARGINAL ENOUGH TO HOLD OFF ON ANY ADVISORIES FOR NOW.

AFTER THAT...HIGH PRESSURE BUILDING ACROSS THE GREAT LAKES WILL
BRING A RETURN TO TRANQUIL CONDITIONS FOR THE MID TO LATE WEEK
PERIOD.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EDT
         MONDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT
         MONDAY FOR LOZ042.
         SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR
         LOZ045.

&&

$$

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






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