Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 161456
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1056 AM EDT TUE SEP 16 2014

.SYNOPSIS...
CLOUDS WILL BREAK UP SOME LATE THIS MORNING ALLOWING FOR SOME BREAKS
OF SUNSHINE...BEFORE MORE CLOUDS MAKE A RETURN THIS AFTERNOON. AN
AREA OF HIGH PRESSURE WILL BRING COOL AND DRY CONDITIONS INTO
WEDNESDAY THEN A WEAK FRONT WILL BRING A SLIGHT CHANCE FOR RAIN
SHOWERS WEDNESDAY NIGHT AND THURSDAY. HIGH PRESSURE RETURNS FOR THE
END OF THE WEEK WITH A HIGH CHANCE OF SHOWERS POSSIBLE LATE IN THE
WEEKEND AS A COMPLEX FRONTAL BOUNDARY IS FORECAST TO CROSS OUR
REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE BROAD UPPER LEVEL TROUGH WILL REMAIN PARKED OVER THE NORTHEAST
THROUGH THE PERIOD KEEPING TEMPERATURES COOLER THAN
AVERAGE...HOWEVER SURFACE HIGH PRESSURE BUILDING IN FROM THE WEST
SHOULD HELP DRY UP ANY LINGERING LAKE ENHANCED LIGHT SHOWER ACTIVITY
BY EARLY THIS AFTERNOON AND KEEP CONDITIONS DRY.

REGIONAL RADARS LATE THIS MORNING SHOWING JUST A FEW ISOLATED LAKE
ENHANCED VERY LIGHT SHOWERS LEFT DOWNWIND OF LAKE ONTARIO ACROSS THE
EASTERN LAKE ONTARIO REGION. WITH 850MB TEMPERATURES OF AROUND +4C
OVER THE WARMER LAKE WATER THERE IS JUST ENOUGH LAKE INDUCED
INSTABILITY FOR THESE SHOWERS IN AN OTHERWISE STABLE ENVIRONMENT ON
THE BACK SIDE OF THE SHORTWAVE TROUGH. LATER THIS MORNING EXPECT
DIURNAL MIXING TO DISRUPT THE WEAK FLOW DRIVING THE SHOWERS OVER THE
LAKES WITH DRIER AIR HELPING TO DRY UP ANY SHOWER ACTIVITY BY EARLY
THIS AFTERNOON. THERE WILL BE SOME BREAKS OF SUN LATE THIS
MORNING/EARLY THIS AFTERNOON...HOWEVER EXPECT DIURNAL CUMULUS TO
DEVELOP THIS AFTERNOON THANKS TO THE COOL TEMPS ALOFT AND LINGERING
LOW LEVEL MOISTURE ACROSS THE REGION. COOL AIR ALOFT WILL KEEP
TEMPERATURE BELOW AVERAGE TODAY WITH HIGHS TOPPING OUT IN THE LOW TO
MID 60S.

TONIGHT HIGH PRESSURE OVER THE MIDWEST STATES WILL RIDGE EAST ACROSS
THE LOWER GREAT LAKES. EXPECT THIS TO TRAP SOME LOW LEVEL MOISTURE
BENEATH A SUBSIDENCE INVERSION SO HAVE KEPT SOME SCATTERED CLOUDS
INLAND FROM THE LAKES. OTHERWISE MAINLY CLEAR SKIES NEAR THE LAKE
SHORES. SOME PATCHY RIVER VALLEY FOG WILL AGAIN BE POSSIBLE ACROSS
THE SOUTHERN TIER. THE CLOUDS WILL HELP KEEP OVERNIGHT LOWS ON THE
WARMER SIDE WITH LOWS ONLY SLIDING BACK INTO THE LOW TO MID 40S.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
A HIGH AMPLITUDE UPPER LEVEL PATTERN WILL BE IN PLACE ACROSS NORTH
AMERICA AS WE OPEN THE PERIOD WITH A DEEP TROUGH ACROSS THE EASTERN
UNITED STATES EXTENDING FROM A POLAR LOW OVER NORTHERN QUEBEC WHILE
STRONG RIDGING WILL BE FOUND OVER THE WEST. HIGH PRESSURE AT THE
SURFACE WILL PROVIDE A SUNNY DAY FOR MUCH OF THE LOWER GREAT
LAKES...HOWEVER A POTENT SHORTWAVE DROPPING AROUND THE BASE OF THE
AFOREMENTIONED UPPER LOW WILL SHUNT A COLD FRONT SOUTH TOWARDS OUR
REGION WITH CLOUDS INCREASING ACROSS THE NORTH COUNTRY ON WEDNESDAY
AS THE COLD FRONT APPROACHES THE REGION. WHILE THE BULK OF THE DPVA
AND ASSOCIATED SHOWER ACTIVITY SHOULD REMAIN NORTH OF THE
BORDER...THERE WILL BE A CHANCE OF A FEW SPRINKLES WEDNESDAY NIGHT
AS THE SURFACE COLD FRONT SAGS SOUTH ACROSS LAKE ONTARIO.

850MB TEMPS OF +4 TO +6C WILL SUPPORT HIGHS IN THE MID 60S ACROSS
THE LOWER ELEVATIONS OF THE FORECAST AREA WHILE HIGHER ELEVATIONS OF
THE SOUTHERN TIER AND NORTH COUNTRY WILL RUN A FEW DEGREES
COOLER...IN THE LOWER 60S. FOR WEDNESDAY NIGHT...ENCROACHING CLOUD
COVER ASSOCIATED WITH THE COLD FRONT WILL KEEP TEMPERATURES LOWS IN
THE MID TO UPPER 40S ALONG THE LAKE PLAINS AND INTO THE NORTH
COUNTRY WHILE ACROSS THE SOUTHERN TIER THERE MAY BE JUST ENOUGH
SOUTHWESTERLY FLOW AHEAD OF THE APPROACHING COLD FRONT TO LIMIT
RADIATIONAL COOLING AND ONLY PRODUCE LOWS IN THE LOW TO MID 40S.

THE COLD FRONT WILL DROP SOUTH OF LAKE ONTARIO AROUND DAYBREAK
THURSDAY MORNING AND CONTINUE TO SAG SOUTH ACROSS THE FORECAST AREA
DURING THE DAY. UPSLOPE NORTHERLY FLOW OFF LAKE ONTARIO BEHIND THE
FRONT COUPLED WITH 850MB TEMPS DROPPING TO AROUND +2C WILL GENERATE
PLENTY OF STRATUS ACROSS MUCH OF WESTERN AND NORTH-CENTRAL NEW
YORK...THOUGH THE NORTH COUNTRY SHOULD SEE SUNSHINE IN THE
AFTERNOON AS IT WILL ESCAPE THE INFLUENCE OF THE LAKE. THE
COMBINATION OF COLD ADVECTION AND ABUNDANT CLOUD COVER WILL MAKE
FOR A CHILLY DAY ACROSS THE AREA WITH HIGHS ONLY EXPECTED TO TOP
OUT IN THE MID 50S.

THE CLOUD COVER SHOULD DIMINISH THURSDAY NIGHT AS THE CENTER OF
THE SURFACE HIGH PASSES TO OUR NORTH AND LOW LEVEL FLOW VEERS AROUND
TO THE EAST...PARTICULARLY EAST OF THE GENESEE VALLEY AND THE
NORTH COUNTRY. THIS CLEARING COUPLED WITH THE VERY DRY AIR
ADVECTING INTO THE REGION COULD RESULT IN THE FIRST WIDESPREAD
FREEZE OF THE SEASON ACROSS THE NORTH COUNTRY WHILE FROST MAY BE
POSSIBLE ELSEWHERE WITH THE EXCEPTIONS OF AREAS NEAR THE LAKE ERIE
AND ONTARIO SHORELINES.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
THE ARCTIC HIGH AND ASSOCIATED COLD AIR WILL MOVE OFF TO THE EAST
ON FRIDAY AS THE HIGH AMPLITUDE PATTERN OF EARLIER IN THE WEEK
BRIEFLY GIVES WAY TO A MORE ZONAL FLOW ACROSS THE NORTHERN TIER OF
THE COUNTRY. WITH THE SURFACE HIGH MOVING OFF TO OUR EAST ON
FRIDAY...INCREASING SOUTHERLY RETURN FLOW WILL ALLOW FOR
TEMPERATURES TO WARM BACK INTO THE 60S ON FRIDAY BEFORE BOOSTING
READINGS INTO THE 70S ON SATURDAY WITH AN ABUNDANCE OF SUNSHINE BOTH
DAYS THANKS TO THE ABUNDANCE OF DRY AIR ACROSS THE REGION.

A MUCH MORE COMPLEX PATTERN EVOLVES FOR THE LATTER HALF OF THE
WEEKEND INTO THE BEGINNING OF NEXT WEEK. THERE ARE ESSENTIALLY THREE
TIERS OF UPPER LEVEL ENERGY THAT WILL BE MAKING THEIR WAY ACROSS
NORTH AMERICA DURING THIS PERIOD. THE FIRST IS OVER HUDSON BAY
ASSOCIATED WITH THE POLAR VORTEX. THE SECOND IS A SHORTWAVE
TRACKING OUT OF THE NORTHERN ROCKIES WITH AN ATTENDANT SURFACE LOW
THAT MOVES INTO THE WESTERN GREAT LAKES SATURDAY. THE THIRD AND
FINAL FACTOR IS THE REMNANTS OF HURRICANE ODILE THAT WILL BE
MEANDERING ACROSS THE SOUTHERN PLAINS BY SATURDAY. TO VARYING
DEGREES THE GLOBAL MODELS PHASE ALL THREE OF THESE SYSTEMS AND BRING
THEM ACROSS EASTERN NORTH AMERICA WITH THE X-FACTOR BEING THE SPEED
AND INTENSITY OF YET ANOTHER PLAYER...A POTENT SHORTWAVE DROPPING
OUT OF THE MACKENZIE BASIN OF FAR NORTHWESTERN CANADA SATURDAY NIGHT
INTO SUNDAY. THIS PARTICULAR FEATURE MAY END UP DIGGING FAR
ENOUGH SOUTH TO GENERATE A LARGE SURFACE CYCLONE OVER WESTERN
ONTARIO ON SUNDAY...AS DEPICTED BY THE ECMWF...OR ARRIVE TOO LATE
TO DO SO AND INSTEAD REINVIGORATE THE WESTERN GREAT LAKES SURFACE
LOW AS IT LIFTS INTO WESTERN QUEBEC. THE GLOBAL GEM IS EVEN
FARTHER NORTH AND EAST WITH THIS FEATURE...HAVING IT MISS OUR
GREAT LAKES LOW ENTIRELY.

IN SPITE OF THE SIGNIFICANT DIFFERENCES IN DETAILS BETWEEN THESE
SCENARIOS...THE TIMING OF IMPACTS ON SENSIBLE WEATHER ACROSS THE
LOWER GREAT LAKES IS SURPRISINGLY SIMILAR. AFTER ONE MORE WARM AND
DRY DAY SUNDAY...SHOWERS WILL LIKELY BREAK OUT ACROSS WESTERN NEW
YORK SOMETIME SUNDAY NIGHT AS THE SURFACE/UPPER LEVEL TROUGHS
APPROACH THE AREA. GIVEN THE STRONG DYNAMICS AT WORK ALONG WITH A
DECENT RETURN FLOW OFF OF MOISTURE OFF OF THE GULF OF MEXICO AND
POTENTIAL CONTRIBUTIONS FROM WHATEVER IS LEFT FROM ODILE...WE COULD
SEE A PERIOD OF MODERATE TO HEAVY RAINFALL SUNDAY NIGHT INTO MONDAY.
A COLD FRONT WILL LIKELY CROSS THE REGION MONDAY BRINGING A
POTENTIALLY SIGNIFICANT COOL-DOWN...ALTHOUGH SIGNIFICANCE OF THIS
COOL-DOWN WILL BE A FUNCTION OF THE FINAL TRACK OF THE AFOREMENTIONED
NORTHWEST CANADIAN SHORTWAVE AND THE DEGREE TO WHICH IT ENHANCES THE
LOW OVER WESTERN ONTARIO AND SUBSEQUENT POSSIBLE OCCLUSION ACROSS
THE GREAT LAKES.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
MIX OF VFR AND MVFR CIGS UNDER MAINLY BKN SKIES LATE THIS MORNING.
ALSO SOME LINGERING ISOLATED LAKE ENHANCE SHOWERS HANGING ON EAST
AND SOUTHEAST OF LAKE ONTARIO. EXPECT THESE TO WANE BY EARLY THIS
AFTERNOON. THERE WILL BE SOME BREAKS OF SUN LATE THIS MORNING/EARLY
THIS AFTERNOON...HOWEVER EXPECT DIURNAL CUMULUS TO DEVELOP THIS
AFTERNOON...WITH SCT/BKN MVFR/LOW VFR CIGS LATE THIS MORNING/EARLY
THIS AFTERNOON LIFTING TO ALL LOW VFR CIGS THIS AFTERNOON.

TONIGHT HIGH PRESSURE WILL RIDGE EAST FROM THE MIDWEST STATES. THIS
WILL TRAP ENOUGH MOISTURE FOR SOME MAINLY VFR LEVEL CLOUDS INLAND
FROM THE LAKES OVERNIGHT. SOME RIVER VALLEY FOG MAY ALSO DEVELOP
ACROSS THE SOUTHERN TIER.

OUTLOOK...
WEDNESDAY THROUGH SATURDAY...GENERALLY VFR. SOME PATCHES OF MVFR
CIGS WEDNESDAY NIGHT. SOME VALLEY FOG WITH LOCALIZED IFR FLIGHT
VSBYS ACROSS THE SOUTHERN TIER EACH MORNING.

&&

.MARINE...
WESTERLY WINDS WILL INCREASE LATER THIS AFTERNOON BEHIND A WEAK
SURFACE TROUGH. CONVERGENT FLOW ALONG THE SOUTHEAST LAKE ONTARIO
NEAR SHORE WATERS HAS ALLOWED A SMALL CRAFT ADVISORY TO CONTINUE
BETWEEN SODUS BAY AND MEXICO BAY OTHERWISE WINDS AND WAVES IN OTHER
ZONES WILL REMAIN BELOW CRITERIA. WINDS AND WAVES WILL GRADUALLY
SUBSIDE LATE TONIGHT INTO WEDNESDAY BEFORE BUILDING ONCE AGAIN
WEDNESDAY NIGHT AS ANOTHER WEAK COLD FRONT DROPS SOUTH OUT OF CANADA.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 2 AM EDT
         WEDNESDAY FOR LOZ044.

&&

$$

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






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