Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 290551
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
151 AM EDT WED OCT 29 2014

.SYNOPSIS...
MUCH COOLER AIR WILL SWEEP BACK INTO THE REGION TODAY WITH A FEW
LAKE EFFECT RAIN SHOWERS EAST OF LAKE ERIE...AND THEN EAST OF LAKE
ONTARIO THIS EVENING. PROGRESSIVELY COLDER WEATHER WILL THEN
CONTINUE FOR THE REMAINDER OF THE WEEK. ANOTHER LOW PRESSURE SYSTEM
IS EXPECTED TO CROSS THE AREA FRIDAY AND SATURDAY WITH RAIN
POTENTIALLY TRANSITIONING INTO THE FIRST SNOWFLAKES OF THE SEASON BY
SATURDAY MORNING.

&&

.NEAR TERM /THROUGH TODAY/...
REGIONAL RADARS THIS EARLY MORNING DISPLAY THE LAST OF THE RAIN
SHOWERS NOW EXITING LEWIS COUNTY. WITH LITTLE POST FRONTAL ACTIVITY
SEEN UPSTREAM EXPECT THE REMAINDER OF THE NIGHT TO REMAIN DRY AND
BREEZY UNDER COLD AIR ADVECTION. IR SATELLITE IMAGERY SUGGESTS THAT
PARTLY TO MOSTLY CLOUDY SKIES WILL REMAIN THROUGH THE NIGHT.

INCREASINGLY COLDER PROFILES IN THE COLD AIR ADVECTION REGIME AND
SUBSEQUENT STEEPER LOW LEVEL LAPSE RATES WILL PRODUCE AN ENVIRONMENT
THAT IS MARGINALLY SUPPORTIVE OF LAKE EFFECT RAIN SHOWERS...MAINLY
OFF LAKE ERIE. LAKE INDUCED CAPE WILL RISE TO AROUND 300J/KG WITH
EQUILIBRIUM LEVELS AROUND 9K FEET. THESE PARAMETERS ARE RATHER TAME
FOR A LAKE EFFECT RAIN SETUP...BUT ARE PROBABLY SUFFICIENT TO
SUPPORT AT LEAST A FEW SHOWERS. ALL THE MESOSCALE MODEL GUIDANCE IS
SUGGESTING A BAND OF LAKE EFFECT RAIN SHOWERS...INCLUDING THE
OPERATIONAL NAM AND CANADIAN GEM AS WELL AS ALL OUR IN-HOUSE
WORKSTATION WRF RUNS. GIVEN THE STRONG MESOSCALE MODEL SUPPORT AND
SUFFICIENT THERMODYNAMICS...HAVE INCREASED POPS TO LIKELY OFF LAKE
ERIE. BAND PLACEMENT IS MOST LIKELY VERY CLOSE TO THE CITY OF
BUFFALO AND SOUTHERN AND EASTERN SUBURBS...EXTENDING EAST INTO
GENESEE/WYOMING COUNTIES. THE RELATIVELY STRONGER FLOW... SYNOPTIC
SCALE MOISTURE AND INSTABILITY SUGGEST THESE SHOWERS WILL EXTEND FAR
INLAND INTO THE FINGER LAKES AND POSSIBLY EVEN CENTRAL NY.

WEDNESDAY WILL BE A SHARPLY COOLER DAY WITHIN THE COLD AIR
ADVECTION PATTERN...WITH HIGHS LIKELY TO BE SOME 20 TO 25 DEGREES
COOLER THAN TODAY AND BACK CLOSE TO WHERE THEY SHOULD BE FOR THE END
OF OCTOBER.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AS THE PERIOD OPENS...THE FORECAST AREA WILL BE TRANSITIONING INTO A
MUCH COOLER REGIME FOR THE LATTER HALF OF THE WEEK AS THE LONGWAVE
TROUGH SETS UP SHOP ACROSS NORTHEASTERN NORTH AMERICA AND THE UPPER
LEVEL JET DROPS SOUTH OF THE GREAT LAKES. THE LOWER GREAT LAKES WILL
REMAIN ON THE SOUTHERN PERIPHERY OF A LARGE AND COMPLEX UPPER LEVEL
LOW CENTERED OVER NORTHERN QUEBEC...PLACING IT UNDER WELL-ALIGNED
WESTERLY FLOW THAT WILL KEEP COOL AIR FLOWING ACROSS THE LAKES AND
ACROSS WESTERN AND NORTH-CENTRAL NEW YORK.

850MB TEMPS RUNNING IN THE -1C TO -3C RANGE WILL CERTAINLY BE COLD
ENOUGH TO MAINTAIN FAIRLY EXTENSIVE LAKE EFFECT CLOUD COVERAGE
ACROSS MUCH OF THE AREA. ANY SHOWER ACTIVITY AND PRECIP AMOUNTS WILL
BE LIMITED CONSIDERABLY BY THE PRESENCE OF MID-LEVEL SUBSIDENCE AND
DRY AIR THAT WILL KEEP INVERSION HEIGHTS GENERALLY AROUND 5-7KFT.
NONETHELESS GIVEN THE MODEST LAKE-INDUCED INSTABILITY...WEST TO
SOUTHWESTERLY UPSLOPE FLOW AND THIN LOW LEVEL MOISTURE PROFILE A
CHANCE OF OCCASIONAL SPRINKLES AND LIGHT SHOWERS WILL REMAIN
POSSIBLE ACROSS THE WESTERN SOUTHERN TIER AND NORTH COUNTY WEDNESDAY
NIGHT. AS WINDS VEER SOUTHWEST ON THURSDAY THE FOCUS WILL BE MORE
SOUTHEAST OF LAKE ONTARIO.

THE COOL AIRMASS AND CLOUDY SKIES WILL YIELD LOWS IN THE UPPER 30S
TO LOWER 40S WEDNESDAY NIGHT WITH THURSDAY STAYING ON THE CHILLY
SIDE...WITH HIGHS AROUND THE 50 DEGREE MARK. THE ARRIVAL OF SLIGHTLY
COOLER AIR THURSDAY NIGHT WILL DROP TEMPERATURES INTO THE MID TO
UPPER 30S.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
THE OPPORTUNITY FOR MORE SIGNIFICANT PRECIPITATION WILL DEVELOP ON
FRIDAY AS A POWERFUL SHORTWAVE IS PROGGED TO DROP OUT OF THE
CANADIAN ARCTIC AND ACROSS THE WESTERN GREAT LAKES THURSDAY
NIGHT...AND TO THE CENTRAL APPALACHIANS BY FRIDAY NIGHT. AS
MENTIONED IN THE PREVIOUS DISCUSSION...THIS SHORTWAVE WILL HAVE A
LONG WAY TO TRAVEL FROM ITS CURRENT POSITION OVER THE BEAUFORT
SEA...AND THIS EXPLAINS THE SUBTLE DIFFERENCES THAT UNFOLD AMONGST
THE MODELS BY THE TIME THE TROUGH REACHES OUR PART OF THE WORLD.
WHILE THESE SUBTLE DIFFERENCES WILL IMPACT BOTH THE EXACT PLACEMENT
OF THE HIGHER POPS AND PRECIP TYPE...THE GENERAL SCENARIO IS THAT
THE STRONG DPVA AND DIFFLUENCE ALOFT WILL DRIVE THE DEVELOPMENT OF A
SURFACE LOW ACROSS THE CENTRAL GREAT LAKES THURSDAY NIGHT. AS THIS
WEAK LOW CROSSES SOUTHERN ONTARIO AND TRACKS OVER THE ALLEGANY
PLATEAU...THE COMBINATION OF UPPER LEVEL FORCING AND LOW/MID-LEVEL
FRONTOGENESIS ON THE NORTHEASTERN FLANK OF THIS SYSTEM SHOULD LEAD TO
THE DEVELOPMENT OF PRECIPITATION ACROSS WESTERN NEW YORK AND EASTERN
ONTARIO FRIDAY.

AT THIS POINT IT APPEARS THAT WHILE THERE MAY BE A POTENTIAL FOR MIXED
PRECIPITATION ACROSS THE HIGHER ELEVATIONS OF THE SOUTHERN TIER AND
NORTH COUNTRY TO START THE DAY ON FRIDAY...THE BULK OF THE
PRECIPITATION DOES NOT LOOK TO ARRIVE UNTIL LATER ON THE DAY...WHEN
ALL OF THE FORECAST AREA SHOULD BE WELL ABOVE FREEZING...AND
RECEIVING A COLD RAIN AS THE DEFORMATION ZONE MOVES OVERHEAD FRIDAY
AFTERNOON INTO THE EVENING.

THE TRICKY FORECAST CONTINUES AS WE MOVE INTO FRIDAY NIGHT AND
SATURDAY MORNING AS THE FULLY MATURE UPPER LOW IS PROGGED TO DIVE
ACROSS THE APPALACHIANS TO THE CAROLINA COAST WHILE SPAWNING A
COASTAL LOW OFF THE EAST COAST. COLD ADVECTION ON NORTHERLY FLOW
DEVELOPING BEHIND THIS SYSTEM WILL LIKELY GENERATE LAKE EFFECT
SHOWERS ACROSS WESTERN AND NORTH-CENTRAL NEW YORK. ONCE
AGAIN...PRECIP TYPE WILL BE AN ISSUE AS TEMPERATURES WILL BE
HOVERING IN THE LOW TO MID 30S WITH A POTENTIAL FOR LIMITED SNOW
ACCUMULATIONS SOUTH OF LAKE ONTARIO...MAINLY ACROSS THE FINGER LAKES
AND PERHAPS THE SOUTHERN TIER FRIDAY NIGHT. CURRENTLY THE MAIN
LIMITING FACTORS TO ANY SIGNIFICANT ACCUMULATIONS ARE THE SHORT
CROSS-LAKE FETCH ON ONTARIO UNDER THE NORTHERLY FLOW WITH NO
GEORGIAN BAY CONNECTION TO ENHANCE MOISTURE FLUX...AND THE
ENCROACHING PRESENCE OF MID-LEVEL RIDGING AND ASSOCIATED SUBSIDENCE
AND DRY AIR THAT WILL FURTHER LIMIT THE ABILITY OF THE LAKE-EFFECT
TO PRODUCE SIGNIFICANT PRECIPITATION...PARTICULARLY AS WE MOVE INTO
SATURDAY.

ONCE LINGERING LAKE EFFECT SHOWERS TAPER OFF SATURDAY...WE SHOULD
SEE A DRYING TREND UNFOLDING FOR THE SECOND HALF OF THE WEEKEND AS
HIGH PRESSURE MOVES OVERHEAD...THOUGH CONTINUED ONSHORE FLOW OFF THE
LAKES WILL KEEP A FAIR AMOUNT OF CLOUD COVER HANGING AROUND THROUGH
SUNDAY. WHILE THERE WILL BE MODEST WARMING SUNDAY...WE SHOULD BE
NOTICEABLY WARMER BY MONDAY AS THE HIGH MOVES TO THE EAST COAST AND
WARM SOUTHERLY FLOW RETURNS TO THE REGION.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT 06Z THE COLD FRONT AND RAIN SHOWERS ARE EXITING EAST WITH ALL 5
TAF SITES IN THE CLEAR AS FAR AS PRECIPITATION GOES FOR THE NEXT 6
HOURS OR SO. THROUGH THE MORNING HOURS AS COLD AIR DEEPENS...A
SOUTHWEST WIND WILL BEGIN TO DEVELOP A BAND OF LAKE EFFECT RAIN
SHOWERS. THIS ACTIVITY MAY BRUSH BY THE KBUF AIRFIELD...FOR WHICH A
VCSH WILL BE IN PLACE. BEHIND A SHORTWAVE WINDS WILL VEER AROUND TO
WEST-NORTHWEST WITH THE LAKE EFFECT RAIN BAND OFF LAKE ERIE DROPPING
SOUTHWARD...AND TOWARDS THE SOUTHERN TIER.

OFF LAKE ONTARIO EXPECT A BAND OF RAIN SHOWERS TO FORM...BUT LIKELY
NOT UNTIL THE LATER AFTERNOON HOURS AS SOUTHWESTERLY WINDS ALIGN.
THIS BAND LIKEWISE WILL DROP SOUTHWARD ACROSS AREAS EAST OF LAKE
ONTARIO THROUGH THE OVERNIGHT TIME PERIOD.

CIGS WILL LARGELY BE VFR THROUGH THE TIME PERIOD...THOUGH SOME
INSTANCES OF MVFR WILL BE LIKELY...ESPECIALLY WITHIN ANY LAKE EFFECT
RAIN BANDS. THESE BANDS OF LAKE EFFECT RAIN WILL DIMINISH IN
INTENSITY THROUGH THE OVERNIGHT AS INVERSION HEIGHTS DROP...AND LOW
LEVEL CONVERGENCE WEAKENS.

OUTLOOK...
THURSDAY...MAINLY VFR...EXCEPT MVFR WITH A CHANCE OF SHOWERS
DOWNWIND OF THE LAKES.
FRIDAY...VFR/MVFR WITH RAIN SHOWERS BECOMING LIKELY FRIDAY...WITH
FURTHER DETERIORATION TO IFR/MVFR AS THE PRECIPITATION CHANGES OVER
TO SNOW SHOWERS FRIDAY NIGHT.
SATURDAY...MVFR/IFR WITH SCATTERED TO NUMEROUS SNOW SHOWERS.
SUNDAY...MAINLY VFR.

&&

.MARINE...
DEEP LOW PRESSURE OVER THE UPPER GREAT LAKES WILL LIFT NORTHEASTWARD
TO JAMES BAY TONIGHT...THEN OUT ACROSS NORTHERN QUEBEC PROVINCE
WEDNESDAY AND THURSDAY. BEHIND THE LOW...WINDS WILL VEER TO WESTERLY
LATE TONIGHT AND WEDNESDAY AND CONTINUING TO REMAIN BRISK. THIS WILL
PRODUCE AN EXTENDED PERIOD OF ADVISORY-LEVEL WINDS AND WAVES ACROSS
THE LOWER LAKES...FOR WHICH SMALL CRAFT ADVISORIES WILL REMAIN IN
EFFECT.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT THURSDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LEZ020.
         SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 11 AM
         EDT THURSDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY UNTIL 5 AM EDT THURSDAY FOR LOZ042.
         SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR LOZ045.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...THOMAS
MARINE...TMA







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