Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 160935
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
435 AM EST TUE DEC 16 2014

.SYNOPSIS...
RAIN SHOWERS WILL SPREAD ACROSS THE AREA TODAY AS A LOW PRESSURE
SYSTEM MOVES THROUGH THE REGION. COLDER AIR WILL MOVE IN BEHIND THIS
SYSTEM FOR WEDNESDAY INTO THURSDAY...RESULTING IN SOME LAKE EFFECT
SNOW SHOWERS EAST AND SOUTHEAST OF THE LAKES. HIGH PRESSURE WILL
RETURN BY FRIDAY AND SATURDAY WITH DRYING CONDITIONS AND NEAR-NORMAL
TEMPERATURES.

&&

.NEAR TERM /THROUGH TONIGHT/...
A WELL-DEFINED UPPER-LEVEL LOW CAN BE SEEN ON WV IMAGERY OVER THE
MIDWEST THIS MORNING. A BAND OF PRECIPITATION EXTENDS OUT AHEAD OF
THIS LOW ACROSS NORTHEAST OH AND NORTHWEST PA AND PUSHING INTO
CHAUTAUQUA COUNTY AS OF 430AM. THIS BATCH OF RAIN SHOWERS WILL
CONTINUE TO LIFT NORTHEASTWARD INTO WESTERN NEW YORK THROUGH
SUNRISE...IMPACTING JAMESTOWN...BUFFALO AND LIKELY ROCHESTER AS
WELL. INDICATIONS FROM WV IMAGERY AND HIGH RESOLUTION MODELS SUGGEST
THIS LINE WILL GLANCE WESTERN NEW YORK AND PIVOT NORTHWARD INTO
CANADA AROUND THE UPPER-LEVEL LOW. THEN ANOTHER BATCH OF SHOWERS
DEVELOPING OVER WEST VIRGINIA AHEAD OF A SECONDARY SHORTWAVE /SEEN
BY THE DRYING IN THE WV IMAGERY OVER TENNESSEE/ WILL LIFT NORTHWARD
THROUGH THE FORECAST AREA. THIS WILL REINFORCE THE INITIAL BATCH OF
PRECIPITATION AND TRANSITION TO THE PRIMARILY LINE THAT MOVES ACROSS
CENTRAL NEW YORK INTO THE NORTH COUNTRY BY THIS EVENING. THE
PRECIPITATION WILL EVOLVE ENTIRELY AS RAIN TODAY AS MOST LOCATIONS
ARE RIGHT NEAR OR JUST ABOVE FREEZING CURRENTLY AND WARM ADVECTION
WITH THE ADVANCING  FRONT WILL PUSH TEMPERATURES INTO THE MID 40S
FOR DAYTIME HIGHS. BEHIND THE ORGANIZED LINE OF SHOWERS THAT MOVE
FROM SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA...EXPECT
CONTINUED SCATTERED TO NUMEROUS RAIN SHOWERS ASSOCIATED WITH THE
UPPER-LEVEL LOW ITSELF AS IT CROSSES THE FORECAST AREA.

LATER TONIGHT...COLD AIR ADVECTION WILL FOLLOW BEHIND THE
UPPER-LEVEL LOW PASSAGE. THE COMBINATION OF COOLER AIR MOVING IN AND
INCREASING WESTERLY FLOW WILL INITIALLY ALLOW FOR SOME LAKE
ENHANCEMENT OF THE RAIN SHOWERS EAST OF THE LAKES...BUT THE
TRANSITION TO ANY LAKE EFFECT SNOW SHOWERS WILL HOLD OFF UNTIL LATER
ON WEDNESDAY AS THE CORE OF COLDER 850 MB TEMPERATURES ARRIVES.

PRECIPITATION AMOUNTS FROM TODAY THROUGH TONIGHT WILL RANGE FROM
AROUND TWO TENTHS OF AN INCH TO AROUND A THIRD OF AN INCH. THE
HIGHER AMOUNTS WILL LIKELY BE JUST EAST OF THE LAKES WHERE SOME LAKE
ENHANCEMENT SHOULD BE EVIDENT TONIGHT.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ON WEDNESDAY AN ELONGATED EAST/WEST ORIENTED MID LEVEL CUTOFF LOW
WILL MOVE SLOWLY EAST DOWN THE OTTAWA VALLEY WITH AN ASSOCIATED
SURFACE LOW TAKING A SIMILAR TRACK BEFORE YIELDING TO SECONDARY
COASTAL CYCLOGENESIS DURING THE AFTERNOON OVER THE GULF OF MAINE.
LARGE SCALE ASCENT FROM DPVA AHEAD OF THE MID LEVEL TROUGH WILL LIFT
OUT OF WESTERN NY DURING THE MORNING AND FOCUS ON THE NORTH COUNTRY
THROUGH THE DAY WHERE DEEPER MOISTURE WILL ALSO REMAIN. THE SYNOPTIC
SCALE ASCENT WILL BE WEAK...SO PRECIP AMOUNTS WILL ALSO BE LIGHT
WITH THE EXCEPTION OF UPSLOPE AND LAKE ENHANCED AREAS.

STEADY COLD ADVECTION WILL YIELD AN AIRMASS JUST COLD ENOUGH FOR
SOME LIMITED LAKE ENHANCEMENT BY THE AFTERNOON WITH LAKE INDUCED
EQUILIBRIUM LEVELS RISING TO NEAR 5K FEET. THE LOW INVERSION HEIGHTS
AND BOUNDARY LAYER SHEAR WILL PRECLUDE TRUE LAKE EFFECT...BUT WILL
AFFORD THE OPPORTUNITY TO ADD SOME MOISTURE TO THE MIX. UPSLOPE FLOW
WILL PLAY A BIGGER ROLE WITH WESTERLY FLOW PRODUCING EFFICIENT
UPSLOPE INTO THE TUG HILL REGION. MOISTURE WILL BE MORE SHALLOW
ACROSS THE WESTERN SOUTHERN TIER...SO EXPECT UPSLOPE AND LAKE
ENHANCEMENT TO BE WEAKER THERE.

PRECIP TYPE WILL BE ALMOST ALL RAIN FIRST THING IN THE MORNING WITH
850MB TEMPS OF -2C OR WARMER AND A MILD BOUNDARY LAYER. COLD
ADVECTION WILL ALLOW RAIN TO MIX WITH AND CHANGE TO SNOW FROM WEST
TO EAST DURING THE DAY AND ALSO FROM HIGHER TERRAIN TO LOWER.
OUTSIDE OF UPSLOPE AND LAKE ENHANCED AREAS FROM BUFFALO TO ROCHESTER
AND THE FINGER LAKES EXPECT PRECIP TO TAPER TO SCATTERED RAIN/SNOW
SHOWERS BY LATE MORNING. ACCUMULATIONS DURING THE DAY WILL BE VERY
MINOR...WITH AN INCH OR SO ACROSS HIGHER TERRAIN AND NO ACCUMULATION
AT LOWER ELEVATIONS. THE COLD ADVECTION WILL OFFSET THE DIURNAL
CYCLE WITH MORNING HIGHS IN THE LOWER 40S AT LOWER ELEVATIONS AND
MID TO UPPER 30S ACROSS HIGHER TERRAIN BEFORE FALLING THROUGH THE
30S DURING THE DAY. IT WILL BECOME WINDY ESPECIALLY NORTHEAST OF
LAKE ERIE FROM THE NIAGARA FRONTIER TO ROCHESTER WHERE GUSTS MAY
REACH 30-35 KNOTS IN THE AFTERNOON.

WEDNESDAY NIGHT THE SURFACE LOW AND MID LEVEL CUTOFF WILL ACCELERATE
EAST TOWARDS THE CANADIAN MARITIMES. THE WESTERN BASE OF THE MID
LEVEL TROUGH WILL SWING ACROSS LAKE ONTARIO AND UPSTATE NY OVERNIGHT
AND PROVIDE A BOOST IN LARGE SCALE ASCENT AND DEEPER MOISTURE WHILE
BOUNDARY LAYER FLOW BECOMES NORTHWEST. THE BEST SNOW WILL CONTINUE
TO BE ACROSS THE TUG HILL REGION DUE TO A COMBINATION OF UPSLOPE
FLOW AND LIMITED LAKE ENHANCEMENT. THIS AREA MAY SEE MODERATE
ACCUMULATIONS WEDNESDAY NIGHT LOCALIZED TO HIGHER TERRAIN...WITH AN
INITIAL ESTIMATE OF 4-6 INCHES POSSIBLE ON THE TUG HILL WITH MUCH
LESS AT LOWER ELEVATIONS. ELSEWHERE LAKE ENHANCED SNOW SHOWERS WILL
SPREAD OUT SOUTHEAST OF BOTH LAKES AS FLOW BECOMES NORTHWEST...WITH
A MINOR COATING OF ACCUMULATION IN SOME AREAS AND 1-2 INCHES FROM
THE BOSTON HILLS AND WYOMING COUNTY DOWN INTO THE WESTERN SOUTHERN
TIER.

THURSDAY AND THURSDAY NIGHT NORTHWEST FLOW WILL CONTINUE TO PRODUCE
SCATTERED SNOW SHOWERS AND FLURRIES...WITH THE BEST CHANCES ACROSS
THE CHAUTAUQUA RIDGE OFF LAKE ERIE AND FROM JUST EAST OF ROCHESTER
TO OSWEGO COUNTY AND THE TUG HILL PLATEAU OFF LAKE ONTARIO. THAT
SAID...LAKE INSTABILITY IS ANEMIC GIVEN THE SHALLOW NATURE OF THE
COOLER AIRMASS...WITH EQUILIBRIUM LEVELS ONLY AROUND 5K FEET. ANY
FURTHER ACCUMULATION WILL BE LIGHT AND SPOTTY AS DEEPER SYNOPTIC
SCALE MOISTURE AND ASCENT ARE SLOWLY STRIPPED AWAY AS LOW PRESSURE
MOVES EAST INTO THE NORTH ATLANTIC.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
WEAK NORTHWEST FLOW AND MARGINAL COLD AIR MAY PRODUCE A FEW MORE
FLURRIES OR LIGHT SNOW SHOWERS SOUTHEAST OF THE LAKES ON FRIDAY
ALONG WITH PLENTY OF CLOUD COVER. THIS SHOULD END BY FRIDAY NIGHT AS
A WEAK RIDGE OF HIGH PRESSURE AT THE SURFACE AND A MID LEVEL RIDGE
BUILD OVER THE LOWER LAKES. EXPECT MORE STRATUS TO BE TRAPPED
BENEATH A SUBSIDENCE INVERSION FRIDAY THROUGH SATURDAY WITH LITTLE
OR NO SUNSHINE...EXCEPT PERHAPS THE NORTH COUNTRY WHERE A DRIER PUSH
MAY REACH SOUTH OUT OF QUEBEC.

SATURDAY NIGHT AND SUNDAY THE FOCUS TURNS TO A SOUTHERN STREAM
SYSTEM. MODEL GUIDANCE HAS STRUGGLED WITH THE TRACK AND INTENSITY
DETAILS OF THIS FEATURE OVER THE PAST FEW DAYS. INTERESTINGLY...THE
NEW 00Z ECMWF HAS TRENDED STRONGLY TOWARDS THE GFS SOLUTION WITH A
MUCH WEAKER AND MORE ELONGATED SYSTEM MOVING THROUGH THE OHIO VALLEY
AND NORTHEAST STATES LATE SATURDAY NIGHT AND SUNDAY. THIS WOULD
YIELD A VERY WEAK SYSTEM...BUT WOULD SPREAD SOME LIGHT SNOW ACROSS
OUR REGION. WITH THIS IN MIND...HAVE CONTINUED WITH A CHANCE OF SNOW
FOR THE SECOND HALF OF THE WEEKEND. GIVEN THE PATTERN EXPECT FURTHER
MODEL DIFFERENCES FOR A FEW MORE DAYS BEFORE THE DETAILS ARE BETTER
RESOLVED.

BEHIND THIS SYSTEM WEAK HIGH PRESSURE SHOULD BRING A RETURN TO DRY
WEATHER FOR MONDAY. TEMPERATURES WILL BE VERY CLOSE TO AVERAGE FOR
MID TO LATE DECEMBER WITH NO PUSH OF ARCTIC AIR THROUGH EARLY NEXT
WEEK.

LOOKING A LITTLE FARTHER AHEAD...THIS WILL CHANGE BY AROUND
CHRISTMAS DAY AS BOTH THE OPERATIONAL GFS AND ECMWF ARE NOW COMING
ON BOARD WITH THE LONGER TERM ENSEMBLE MEANS IN DEVELOPING A
STRONGER POSITIVE PNA PATTERN ACROSS NORTH AMERICA WITH A BUILDING
WESTERN RIDGE AND CENTRAL AND EASTERN TROUGH. THE GEFS ENSEMBLE MEAN
TRENDS THE NAO INDEX STEADILY DOWNWARD THROUGH THE END OF THE MONTH
INDICATING A GREATER POTENTIAL FOR HIGH LATITUDE BLOCKING. EXPECT
MID WINTER COLD TO ARRIVE NEAR CHRISTMAS AND HAVE SOME STAYING
POWER. THERE IS STILL A STRONG SUGGESTION IN ENSEMBLE GUIDANCE THAT
THIS PATTERN CHANGE MAY BE USHERED IN BY A STRONG SYSTEM AROUND
CHRISTMAS. STAY TUNED.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
LARGELY MVFR/IFR CONDITIONS PERSIST EARLY THIS MORNING DUE TO
COMBINATION OF A LOW STRATUS DECK AND SOME PATCHY FOG ACROSS WESTERN
NEW YORK. THERE IS A BRIEF WINDOW FOR SOME LOCALIZED VFR CONDITIONS
BETWEEN NOW AND MID-MORNING BEFORE RAIN SHOWERS OVERSPREAD THE
REGION. KBUF IS THE ONLY TAF SITE THAT HAS BEEN ABLE TO SEE SOME VFR
CONDITIONS SO FAR.

ONCE RAIN SHOWERS OVERSPREAD THE REGION FROM MID-MORNING THROUGH THE
DAY...EXPECT FLIGHT CONDITIONS TO BECOME LARGELY MVFR. THE EXCEPTION
WILL BE KJHW WHICH IS THE MOST LIKELY TO REMAIN IFR THROUGH THE DAY.

BY LATER THIS AFTERNOON INTO THIS EVENING...RAIN SHOWERS WILL BECOME
MORE SCATTERED BUT FLIGHT CONDITIONS WILL REMAIN LARGELY IFR/MVFR
FROM LOW CEILINGS.

OUTLOOK...
WEDNESDAY...VFR/MVFR WITH A CHANCE OF RAIN AND SNOW SHOWERS.
WEDNESDAY NIGHT AND THURSDAY...VFR/MVFR WITH SCATTERED TO
OCCASIONALLY MORE NUMEROUS SNOW SHOWERS.
FRIDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS.
SATURDAY...VFR.

&&

.MARINE...
LIGHT SOUTHERLY WINDS WILL PERSIST TODAY THROUGH THIS EVENING.  THEN
A LOW PRESSURE SYSTEM WILL PASS ACROSS SOUTHERN CANADA  BRINGING
WIDESPREAD ADVISORY WINDS AND WAVES TONIGHT THROUGH THURSDAY NIGHT.
GIVEN HIGH CONFIDENCE IN THESE HIGHER WINDS AND WAVES HAVE ISSUED
SMALL CRAFT ADVISORIES FOR BOTH LAKES FROM TONIGHT THROUGH THURSDAY
NIGHT.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM WEDNESDAY TO 4 AM EST THURSDAY
         FOR LEZ020.
         SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 PM EST
         THURSDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 7 AM WEDNESDAY TO 4 AM EST
         THURSDAY FOR LOZ030.
         SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 4 AM EST
         FRIDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY FROM 8 AM WEDNESDAY TO 10 PM EST
         THURSDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM NOON WEDNESDAY TO 4 AM EST
         FRIDAY FOR LOZ045.

&&

$$

SYNOPSIS...CHURCH
NEAR TERM...CHURCH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...CHURCH
MARINE...CHURCH







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