Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 311139
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
739 AM EDT FRI OCT 31 2014

.SYNOPSIS...
A WEAK WARM FRONT WILL EXTEND EASTWARD ACROSS THE VICINITY OF LAKE
ONTARIO TODAY...WITH A FEW LIGHT SHOWERS THIS MORNING. THESE SHOWERS
WILL BECOME MORE NUMEROUS THIS AFTERNOON AS AN AREA OF LOW PRESSURE
DRAWS CLOSER TOWARDS LAKE ERIE. BEHIND THIS AREA OF LOW PRESSURE
CHILLY TEMPERATURES ARE EXPECTED FOR THE WEEKEND ALONG WITH
OCCASIONAL RAIN SHOWERS SATURDAY. MOST OF THE PRECIPITATION IS
EXPECTED TO REMAIN LIQUID...ALTHOUGH A FEW WET SNOWFLAKES MAY MIX IN
SATURDAY NIGHT. A WARMING TREND IS THEN EXPECTED EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SURFACE ANALYSIS THIS MORNING DISPLAYS AN AREA OF LOW PRESSURE OVER
LAKE HURON...WITH A WARM FRONT EXTENDING EASTWARD TOWARDS THE
VICINITY OF LAKE ONTARIO. REGIONAL RADARS DISPLAY RAIN SHOWERS
BLOSSOMING THIS MORNING OVER LAKE ERIE...WITH ACTIVITY EXPANDING
ACROSS THE NORTHERN NIAGARA FRONTIER AND TOWARDS WESTERN LAKE
ONTARIO ALONG THE WARM FRONT BOUNDARY. COOL AIR ALOFT OVER THE
WARMER LAKES IS BRINGING ENOUGH INSTABILITY THIS MORNING TO ENHANCE
THESE SHOWERS OVER THE WATER BODIES. OTHERWISE ABUNDANT LOW LEVEL
MOISTURE WILL MAINTAIN STRATUS WHILE MID LEVEL CLOUDS ALSO INCREASE.
THIS WILL KEEP WESTERN NEW YORK RATHER CLOUDY...WHILE A FEW BREAKS
ARE POSSIBLE TO AREAS EAST OF LAKE ONTARIO.

WATER VAPOR IMAGERY THIS MORNING DISPLAYS A VIGOROUS SHORTWAVE
TROUGH OF LOW PRESSURE DROPPING SOUTHEASTWARD INTO THE BASE OF A DEEP
LONGWAVE TROUGH. THIS SHORTWAVE OVER THE UPPER GREAT LAKES WILL DROP
TOWARDS THE SOUTHEASTERN US BY SATURDAY MORNING. ON THE 1.5 PV
SURFACE...A SPLIT IN THIS SHORTWAVE IS SEEN...WITH THE MAIN
SHORTWAVE OVER THE SOUTHERN EASTERN US...WHILE A DOWNWARD INTRUSION
OF ENERGY LINGERS OVER THE CANADIAN NIAGARA PENINSULA TONIGHT.

THIS UPPER LEVEL SHORTWAVE WILL DRIVE THE SURFACE LOW
SOUTHEASTWARD...WITH THE WEAK LOW DROPPING TOWARDS THE WESTERN HALF
OF LAKE ERIE THIS EVENING BEFORE WEAKENING AS LEE SIDE CYCLOGENESIS
FORMS ALONG THE CAROLINA COASTLINE OVERNIGHT...WITH A SECONDARY LOW
DEEPENING. TRACKING THE SURFACE LOW...WHICH WILL CENTER THE BETTER
LOW LEVEL CONVERGENCE WE WILL FIND LIKELY SHOWERS REACHING WNY LATER
THIS AFTERNOON...WITH THE GREATEST CHANCES FOR SHOWERS REMAINING
ACROSS OUR WESTERN ZONES OVERNIGHT. TOWARDS THE EAST...WHICH WILL
LARGELY REMAIN AWAY FROM THE INFLUENCES OF THE SURFACE LOW TODAY...
LOW CHANCE POPS WILL REMAIN IN PLAY FOR SHOWERS...WITH ANY ACTIVITY
LARGELY THIS EVENING AND OVERNIGHT.

THE LINGERING UPPER LEVEL PV INTRUSION/ENERGY ALOFT WILL PROVIDE FOR
ADDITIONAL LIFT OVERNIGHT. A STRENGTHENING NORTHEAST WIND AROUND
THIS SECONDARY...DEEPENING ATLANTIC COASTLINE LOW WILL FOCUS LOW
LEVEL MOIST CONVERGENCE ALONG THE SOUTHERN AND WESTERN END OF THE
LAKE ONTARIO SHORELINE OVERNIGHT. THIS LOW LEVEL
CONVERGENCE...COMBINED WITH LIFT ALOFT WILL BRING CATEGORICAL LIGHT
RAIN SHOWERS TOWARDS FAR WESTERN NEW YORK ZONES LATER OVERNIGHT.
TEMPERATURE PROFILES WOULD SUGGEST THAT ALL FALLING PRECIPITATION
THROUGH THIS TIME PERIOD WILL REMAIN AS LIQUID.

CLOUDS WILL REMAIN RATHER THICK THROUGH THIS TIME PERIOD...WHICH IN
ADDITION TO THE LOWERING SUN ANGLE WILL PROVIDE FOR A SMALL DIURNAL
TEMPERATURE RANGE. HIGHS TODAY WILL ONLY BEST THEIR MORNING
TEMPERATURES BY 5-10 DEGREES...WITH HIGHS IN THE MID TO UPPER 40S. A
FEW 50S ARE POSSIBLE SE OF LAKE ONTARIO. TONIGHT LOWS WILL DROP OFF
TO THE MID TO UPPER 30S. WARMEST AREAS OVERNIGHT WILL LIKELY BE TO
THE SW OF LAKE ONTARIO WHERE NORTHEAST WINDS OVER THE YET STILL WARM
LAKE ONTARIO WILL LIKELY KEEP OVERNIGHT TEMPERATURES AROUND 40.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
THE WEEKEND WILL START OFF CHILLY AND WET AS A COMPLEX LOW DEVELOPS
ALONG THE ATLANTIC COAST. MODEL DIFFERENCES WITH THIS SYSTEM WILL
ONLY HAVE A SMALL IMPACT ON OUR REGION WITH AGREEMENT THAT AN UPPER
LEVEL TROUGH AND A COOL NORTHERLY FLOW AT THE SURFACE WILL DRIVE OUR
WEATHER ON SATURDAY. SATURDAY WILL START OFF WITH THE BOUNDARY LAYER
TOO WARM TO SUPPORT SNOW...BUT 850MB TEMPERATURES WILL GRADUALLY
COOL FROM WEST TO EAST. THE NAM/SREF TEND TO BE WARMER THAN GFS/RGEM
GUIDANCE...BUT USING A CONSENSUS 850MB TEMPERATURES SHOULD DROP TO
-3C TO -5C SATURDAY AFTERNOON. THIS WILL CAUSE PRECIPITATION TO MIX
WITH SNOW IN SOME LOCATIONS SATURDAY AFTERNOON...MAINLY IN WESTERN
AREAS AND ACROSS HIGHER TERRAIN. THE BEST LIFT WILL BE BELOW
700MB...PRIMARILY FROM UPSLOPING AND MODEST LAKE ENHANCEMENT. WITH
LIGHT PRECIPITATION...ANY ACCUMULATION DURING THE DAYTIME HOURS ON
SATURDAY WOULD BE LIGHT AND CONFINED TO HIGHER TERRAIN. HIGH
TEMPERATURES ON SATURDAY WILL ONLY BE IN THE LOWER 40S IN MOST
LOCATIONS...WHICH IS ABOUT 10 DEGREES BELOW NORMAL.

THE UPPER LEVEL TROUGH AXIS WILL SLIDE TO OUR EAST ON SATURDAY NIGHT
WITH DRIER MID-LEVEL AIR FORECAST TO BUILD INTO OUR REGION FROM
CENTRAL CANADA. MEANWHILE TEMPERATURES WILL CONTINUE TO COOL...WITH
LAKE ENHANCEMENT AND SOME ATLANTIC MOISTURE KEEPING THE SURFACE TO
700MB COLUMN MOIST. HOWEVER...THE DRY AIR ALOFT WILL HINDER SNOW
WITH MOST OF THE DENDRITIC SNOW GROWTH ZONE DRY. IT MAY BE JUST COOL
ENOUGH FOR SNOW SHOWERS...OR PRECIPITATION MAY FALL AS DRIZZLE OR
FREEZING DRIZZLE. THE BEST CHANCE FOR PRECIPITATION SHOULD BE ACROSS
THE GENESEE VALLEY AND FINGER LAKES REGIONS WHERE THERE WILL BE A
SLIGHTLY LONGER FETCH ACROSS LAKE ONTARIO AND MORE MOISTURE FROM THE
COASTAL LOW. AS DRIER AIR CONTINUES TO BUILD IN...LINGERING
PRECIPITATION SHOULD FIZZLE OUT ON SUNDAY...EVOLVING INTO
LAKE-INDUCED STRATUS. IT STILL APPEARS ANY SNOW ACCUMULATIONS WILL
BE VERY LIGHT. TEMPERATURES WILL DROP BELOW FREEZING IN MOST AREAS
WITH LOWS IN THE UPPER 20S TO LOWER 30S ON SATURDAY NIGHT. THIS MAY
RESULT IN A FEW ICY SPOTS SATURDAY NIGHT IF THERE ARE ANY WET SPOTS
FROM PRECIPITATION EARLIER IN THE DAY.

HIGH PRESSURE WILL RIDGE IN FROM THE WEST ON SUNDAY...BRINGING FAIR
WEATHER AND GRADUALLY CLEARING SKIES. CLOUDS SHOULD LAST MUCH OF THE
DAY ACROSS INTERIOR SECTIONS WITH COOL AIR ALOFT RESULTING IN LAKE
ENHANCED STRATUS. SOME BREAKS OF SUN ARE LIKELY SUNDAY AFTERNOON
NEAR THE LAKES AND IN WESTERN SECTIONS. HIGHS WILL CHILLY...ONLY BE
IN THE UPPER 30S TO LOWER 40S.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL BUILD ACROSS OUR REGION SUNDAY NIGHT AND
MONDAY...WITH FAIR WEATHER AND WARMER TEMPERATURES. FLOW BACKING TO
THE SOUTHWEST WILL ADVECT WARMER AIR ACROSS THE LOWER GREAT
LAKES...PUSHING TEMPERATURES BACK ABOVE THE 50 DEGREE MARK MONDAY
AND BY TUESDAY MANY AREAS WILL CLIMB INTO THE UPPER 50S WITH PERHAPS
A 60 DEGREE READING OR TWO NOT OUT OF THE QUESTION IN THE TYPICALLY
WARMER SPOTS OF THE GENESEE VALLEY AND NORTH OF THE FINGER LAKES.
ALTHOUGH THE WARM ADVECTION WILL PUT AN END TO ANY LAKE EFFECT CLOUD
COVER...THERE WILL STILL BE PLENTY OF MID AND HIGH CLOUDS TO GO
AROUND MONDAY AND TUESDAY COURTESY OF WARM ADVECTION ALOFT.

AFTER A DRY START TO THE WEEK...WE WILL SEE SHOWERS CREEP BACK INTO
THE FORECAST AS A POTENT UPPER LEVEL TROUGH AND ACCOMPANYING SURFACE
LOW LIFT FROM WESTERN ONTARIO INTO NORTHERN QUEBEC. AS THE LOW
TRACKS INTO NORTHERN QUEBEC...IT WILL DRAG A TRAILING COLD FRONT
ACROSS THE LOWER GREAT LAKES TUESDAY NIGHT. 00Z MODEL GUIDANCE
INDICATES A SMALL CHANCE OF SHOWERS IN WESTERN AREAS MONDAY NIGHT
AND TUESDAY...HOWEVER THE BETTER PRECIP CHANCES WILL BE ASSOCIATED
WITH THE PASSAGE OF THE COLD FRONT TUESDAY NIGHT INTO WEDNESDAY
GIVEN THE FAVORABLE FRONTOGENETIC AND UPPER LEVEL FORCING AND RETURN
FLOW SUPPLYING GULF MOISTURE ACROSS THE OHIO VALLEY AND LOWER LAKES
ALONG THE FRONTAL BOUNDARY.

00Z/12Z MODEL ECMWF/GFS/GGEM GUIDANCE IS IN POOR AGREEMENT FOR THE
WEDNESDAY AND THURSDAY TIMEFRAME...WITH SOME GUIDANCE DEVELOPING A
FRONTAL WAVE WHILE OTHER GUIDANCE FORECASTING A MORE PROGRESSIVE
FRONTAL PASSAGE. GIVEN THESE DIFFERENCES...WILL JUST COVER THE
PERIOD WITH LOW CHANCE POPS FOR THE TIME BEING AND USE A MULTI-MODEL
BLEND FOR TEMPERATURES WHICH IS ALSO PRETTY CLOSE TO CLIMATOLOGY.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT 12Z MAINLY VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION.
WITHIN AN AREA OF LIGHT SHOWERS AND DRIZZLE A DECK OF STRATUS HAS
LOWERED TO MVFR OVER THE NORTHERN NIAGARA FRONTIER. THESE CONDITIONS
WILL PERSIST FOR A FEW MORE HOURS BEFORE THE WARM FRONT LIFTS
FARTHER NORTHWARD...AND DAYTIME MIXING INCREASES.

WILL CONTINUE THE VCSH AND ADD -DZ TO THE KBUF/KIAG TAFS FOR THE
NEXT SEVERAL HOURS THIS MORNING FOR THESE SCATTERED LIGHT RAIN
SHOWERS...WITH SHOWERS ENDING AS THEY LIFT NORTHWARD.

LATER IN THE DAY THESE RAIN SHOWERS ARE EXPECTED TO BECOME MORE
NUMEROUS AS THE WARM FRONT`S PARENT LOW DROPS SOUTHEASTWARD ACROSS
LAKE ERIE. SHOWER ACTIVITY IS EXPECTED TO BE LIKELY ACROSS WESTERN
NEW YORK AND LIGHT RAIN SHOWERS WILL BE PLACED IN THESE TAFS...WHILE
HOLDING JUST A VCSH FOR THE KART TERMINAL AND EASTERN LAKE ONTARIO
LOCATIONS WHERE RAIN SHOWERS WILL LIKELY BE ISOLATED IN NATURE.

A DEEPENING UPPER LEVEL TROUGH OVER THE OHIO VALLEY WILL SETTLE
TOWARDS THE CAROLINAS BY SATURDAY MORNING. THIS LOW PRESSURE OVER
LAKE ERIE WILL REFORM AND INTENSIFY EAST OF THE APPALACHIANS LATE
TONIGHT. AS THE LOW SURFACE PRESSURE CROSSES THE REGION...COMBINED
WITH THE NEARING UPPER LEVEL TROUGH LIGHT RAIN SHOWERS ARE LIKELY
THROUGH THE NIGHT TONIGHT...AGAIN MOST LIKELY FARTHER WESTWARD.

BEHIND THIS AREA OF LOW PRESSURE WINDS WILL INCREASE FROM THE
NORTH-NORTHEAST. COOLER AIR FLOWING BEHIND THIS LOW PRESSURE
COMBINED WITH THE NORTHEAST WINDS WILL LIKELY FORM MVFR AND LATER
IFR FLIGHT CONDITIONS FRIDAY NIGHT. CLIMATOLOGY PLACES IFR AT BETTER
THAN 50 PERCENT FOR KJHW...WHILE THE NORTHEAST FLOW OFF LAKE ONTARIO
MAY ALSO BRING IFR CIGS FOR KROC...IN ADDITION TO KIAG AND KBUF.

OUTLOOK...
SATURDAY...AREAS OF MVFR/IFR WITH OCCASIONAL SHOWERS.
SUNDAY...MVFR IMPROVING TO VFR WITH SCATTERED SPRINKLES AND
FLURRIES.
MONDAY...MAINLY VFR.
TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A WEAK AREA OF LOW PRESSURE DROPPING SOUTHEASTWARD OVER THE WESTERN
END OF LAKE ERIE TODAY WILL BRING LIGHT WINDS TO THE LAKES.

A STRONGER LOW PRESSURE WILL DEVELOP OFF THE MID ATLANTIC COASTLINE
THIS WEEKEND...AND NORTHEAST WINDS AROUND THIS LOW WILL INCREASE
FIRST ON LAKE ONTARIO FRIDAY NIGHT...AND SATURDAY MORNING ON LAKE
ERIE.

IN RESPONSE TO THE INCREASE IN WIND SPEEDS...WAVE HEIGHTS SHOULD
INCREASE TO 4 TO 7 FEET...ESPECIALLY ACROSS WESTERN LAKE ONTARIO
THROUGH THE DAY SATURDAY. WHILE WAVES WILL BE GREATEST ON THE
WESTERN END OF LAKE ONTARIO...AND ALSO THE WESTERN END OF LAKE
ERIE...HAVE ISSUED SCA FOR THE ENTIRE LAKE ONTARIO REGION...AND
THE EASTERN HALF OF LAKE ERIE AS WINDS AND WAVES SHOULD TOP SCA
THRESHOLDS AT TIMES THIS WEEKEND. THESE NORTHEASTERLY TO LATER THIS
WEEKEND NORTHWESTERLY WINDS WILL ALSO BRING SCA CONDITIONS
TO THE LOWER NIAGARA RIVER.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM EDT SATURDAY TO 4 AM EST SUNDAY
         FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 2 AM EDT SATURDAY TO 1 AM
         EST SUNDAY FOR LOZ030.
         SMALL CRAFT ADVISORY FROM MIDNIGHT EDT TONIGHT TO 7 AM EST
         MONDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY FROM MIDNIGHT EDT TONIGHT TO 1 AM EST
         MONDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM 6 AM TO 8 PM EDT SATURDAY FOR
         LOZ045.

&&

$$

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







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