Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 211622
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1222 PM EDT SUN SEP 21 2014

.SYNOPSIS...
OCCASIONAL SHOWERS WILL ACCOMPANY A COLD FRONT AS IT CROSSES THE
AREA LATER 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/...
SURFACE ANALYSIS THIS MORNING DEPICTS A 999MB SURFACE LOW CENTERED
JUST TO THE NORTH OF TORONTO. THIS SURFACE LOW IS BEING DRIVEN BY
STRONG DPVA ASSOCIATED WITH A VIGOROUS UPPER LEVEL LOW OVER NORTHERN
LOWER MICHIGAN. A BAND OF SHOWERS WITH A FEW ISOLATED THUNDERSTORMS
THAT MOVED THROUGH WESTERN NEW YORK EARLIER THIS MORNING ASSOCIATED
WITH A LEAD SHORTWAVE NOW MOVING INTO THE NORTH COUNTRY. WHILE WV
AND VISIBLE SATELLITE IMAGERY ARE SHOWING A WELL DEFINED DRY SLOT
WRAPPING ACROSS WESTERN NEW YORK RIGHT NOW...WE ARE ALREADY STARTING
TO SEE MORE SHOWERS FLARE UP ACROSS THE WESTERN SOUTHERN TIER THAT
ARE CORRELATING WITH AN AREA OF 500+ J/KG SURFACE-BASED CAPE PER SPC
MESOANALYSIS GRAPHICS. WITH SUCH A STRONG UPPER LEVEL TROUGH
APPROACHING THE AREA...EXPECT SHOWERS AND PERHAPS AN OCCASIONAL
RUMBLE OF THUNDER TO REMAIN IN PLAY THROUGH THE REST OF THE
AFTERNOON. IN ADDITION...THE INSTABILITY IS ALLOWING STRONG
SOUTHWESTERLY WINDS TO MIX DOWN TO THE SURFACE WITH GUSTS TO AROUND
35 MPH ACROSS WESTERN NEW YORK. EXPECT THIS ZONE OF GUSTY WINDS
CORRESPONDING TO THE POSITION OF THE LOW-LEVEL JET TO CONTINUE
THROUGH THE AFTERNOON AND MOVE EAST AS THE SURFACE/MID-LEVEL LOW
LIFTS OFF TO THE NORTHEAST.

A STRONG COLD FRONT ASSOCIATED WITH THE AFOREMENTIONED LOW PRESSURE
SYSTEM LOCATED JUST TO OUR WEST OVER SOUTHERN ONTARIO AND WESTERN
LAKE ERIE WILL TRACK INTO WESTERN NEW YORK LATE THIS AFTERNOON INTO
THIS EVENING. WHILE THE BULK OF THE SHOWER ACTIVITY WILL BE FOCUSES
AHEAD OF THE SURFACE FRONT...WE CAN EXPECT ANOTHER ROUND OF SHOWERS
BEHIND THE FRONT TONIGHT AS THE DEEP UPPER LEVEL TROUGH AND
WRAP-AROUND MOISTURE MOVE ACROSS THE LOWER GREAT LAKES. GIVEN THE
RAPIDLY COOLING TEMPERATURES BEHIND THE FRONT WITH 850MB TEMPS
FALLING INTO THE +2C TO +4C RANGE...EXPECT THERE TO BE SOME LAKE
ENHANCEMENT AND UPSLOPE CONTRIBUTIONS TO SHOWER ACTIVITY EAST OF THE
LAKES AS WELL.

REGARDING TEMPERATURES...A WARM...BUT WINDY AFTERNOON CAN BE
EXPECTED FOR MUCH OF THE FORECAST AREA WITH TEMPERATURES CLIMBING
WELL INTO THE 70S...PARTICULARLY ACROSS THE LAKE ONTARIO PLAIN WHERE
DOWNSLOPING SOUTHWESTERLY FLOW WILL ADD A COUPLE OF DEGREES. HIGHER
ELEVATIONS WILL RUN IN THE UPPER 60S TO LOWER 70S. LOOK FOR
TEMPERATURES TOO FALL OFF RAPIDLY BEHIND THE COLD FRONT TONIGHT WITH
READINGS FALLING TO THE UPPER 40S/LOWER 50S BY DAYBREAK.

&&

.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 AROUND 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 AROUND 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 /18Z SUNDAY THROUGH FRIDAY/...
SOUTHWESTERLY WINDS ARE BEGINNING TO PICK UP SHARPLY IN THE WAKE OF
THE PASSAGE OF AN UPPER LEVEL DISTURBANCE EARLIER THIS MORNING AND
IN ADVANCE OF ANOTHER...STRONGER LOW PRESSURE SYSTEM AND COLD FRONT
THAT WILL BE CROSSING THE FORECAST AREA LATE THIS AFTERNOON AND THIS
EVENING. EXPECT GUSTS OF 20-30 KNOTS AT TIMES AS STRONG WINDS MIX
DOWN TO THE SURFACE THIS AFTERNOON. WHILE THE INITIAL ROUND OF
SHOWERS...WITH ISOLATED THUNDERSTORMS ACROSS THE EASTERN END OF LAKE
ONTARIO AND THE NORTH COUNTRY...WILL CONTINUE TO MOVE OFF TO THE
EAST OVER THE NEXT COUPLE OF HOURS WITH A BRIEF PERIOD OF CLEARING
TO FOLLOW AS A DRY SLOT MOVES OVERHEAD...VFR/MVFR CIGS WILL MOVE
BACK IN ACROSS THE REGION THIS AFTERNOON AS WRAP-AROUND MOISTURE AND
SYNOPTIC FORCING AHEAD OF THE NEXT LOW PRESSURE SYSTEM AND COLD
FRONT MOVE INTO THE FORECAST AREA.

ANOTHER ROUND OF SHOWERS...AND POSSIBLY AN ISOLATED THUNDERSTORM OR
TWO WILL ACCOMPANY THE COLD FRONT WITH WINDS SHIFTING AROUND TO THE
NORTHWEST BEHIND THE FRONT. MUCH COOLER AIR WILL FLOW ACROSS THE
REGION BEHIND THE FRONT...AND THIS IS EXPECTED TO GENERATE A
SIGNIFICANT AMOUNT OF LAKE-EFFECT CLOUD COVER ACROSS THE FORECAST
AREA WITH WIDESPREAD MVFR CIGS DEVELOPING AFTER
00-03Z...DETERIORATING TO IFR ACROSS THE HIGHER
ELEVATIONS...INCLUDING KJHW...FOR THE REST OF THE TAF PERIOD.

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...
RECENT OBSERVATIONS ON THE WESTERN END OF LAKE ERIE CORRELATE WELL
WITH MODEL GUIDANCE IN INDICATING A STRONG SOUTHWESTERLY PUSH OF
WINDS DOWN LAKE ERIE IN THE WAKE OF A PASSING UPPER LEVEL
DISTURBANCE THAT MOVED THROUGH THE AREA EARLIER THIS MORNING. THIS
WILL RESULT IN THE RAPID ONSET OF SMALL CRAFT ADVISORY CONDITIONS ON
THE EAST END OF LAKE ERIE AND THE UPPER NIAGARA RIVER THIS MORNING.
A SMALL CRAFT ADVISORY HAS BEEN ISSUED ACCORDINGLY. EXISTING SMALL
CRAFT ADVISORIES ON LAKE ONTARIO HAVE ALSO BEEN ADJUSTED TO REFLECT
THIS SOUTHWESTERLY PUSH THIS AFTERNOON.

OTHERWISE...EXPECT GUSTY SOUTHWESTERLY WINDS AHEAD OF AN APPROACHING
COLD FRONT TO VEER AROUND TO THE NORTHWEST TONIGHT AS THE FRONT
CROSSES THE LAKES. THE FRESHENING NORTHWESTERLIES AND ASSOCIATED
COLD ADVECTION WILL BRING A SUBSTANTIAL INCREASE IN WAVE-ACTION
ALONG THE SOUTH SHORES OF THE LAKES...PARTICULARLY ON LAKE ONTARIO
WHERE WAVES WILL BUILD INTO THE 4-6 FOOT RANGE LATE TONIGHT INTO
MONDAY. THE SHORTER NORTHWESTERLY FETCH ON LAKE ERIE SHOULD KEEP
WAVES SLIGHTLY LOWER...IN THE 3 TO 4 FOOT RANGE.

WAVES WILL GRADUALLY SUBSIDE MONDAY NIGHT AS AN EXPANSIVE DOME OF
HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES. THIS HIGH WILL SLOWLY
MOVE OVER THE LAKES THROUGH THE REST OF THE COMING WEEK...RESULTING
IN AN EXTENDED PERIOD OF TRANQUIL CONDITIONS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 2 AM EDT MONDAY FOR LEZ020.
         SMALL CRAFT ADVISORY UNTIL 1 AM EDT TUESDAY FOR
         LOZ043-044.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT MONDAY FOR LOZ042.
         SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR LOZ045.

&&

$$

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






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