Area Forecast Discussion
Issued by NWS Buffalo, NY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KBUF 161835
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
135 PM EST TUE DEC 16 2014

.SYNOPSIS...
PERIODS OF RAIN SHOWERS WILL CONTINUE THIS AFTERNOON THROUGH TONIGHT
ACROSS THE AREA AS A LOW PRESSURE SYSTEM MOVES THROUGH THE REGION.
COLDER AIR WILL MOVE IN BEHIND THIS SYSTEM FOR WEDNESDAY INTO
THURSDAY...RESULTING IN A MIX OF RAIN AND SNOW CHANGING TO 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 NEGATIVELY TILTED UPPER-LEVEL TROUGH IS SEEN ON WATER VAPOR IMAGERY
THIS AFTERNOON SHIFTING ACROSS THE MIDWEST AND OHIO VALLEY WITH A
DEEPER REINFORCING UPPER LOW ENTERING THE TROUGH ACROSS MINNESOTA.
SURFACE LOW PRESSURE IS CENTERED NEAR DETROIT WITH RADAR IMAGERY
SHOWING A LEADING BAND OF RAIN SHOWERS ORIENTED ALONG A WARM/OCCLUDED
FRONT EXTENDING EAST AND SOUTH ACROSS LAKE ONTARIO AND CENTRAL NEW
YORK. MORE SCATTERED SHOWERS ARE SEEN TO THE WEST OF THIS LEADING
BAND BENEATH THE UPPER TROUGH OVER EASTERN MICHIGAN AND NORTHERN
OHIO.

RADAR LOOPS AND MESOSCALE MODELS ARE ALL POINT TOWARD THE LEADING
BAND OF RAIN SHOWERS SHIFTING NORTH AND EAST ACROSS CENTRAL NEW
YORK WITH SCATTERED/NUMEROUS SHOWERS THEN FILLING IN ACROSS WESTERN
NEW YORK AS THE SURFACE LOW AND UPPER TROUGH CONTINUE TO PIVOT NORTH
AND EASTWARD. TEMPERATURES EXPECTED TO RISE INTO THE LOW TO MID 40S
THIS AFTERNOON AS SOME WARM AIR IS ADVECTED NORTH BEHIND THE
OCCLUSION.

LATER TONIGHT...A SHOT OF COLD AIR WILL ARRIVE ACROSS THE REGION AS
THE AFOREMENTIONED CLOSED LOW OVER MINNESOTA DIGS OUT THE UPPER
TROUGH ACROSS THE CENTRAL LAKES AND THE CENTER OF THE SURFACE LOW
SHIFTS ACROSS THE WESTERN END OF LAKE ONTARIO. 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 THROUGH TONIGHT WILL RANGE AVERAGE AROUND A
QUARTER 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 /19Z TUESDAY THROUGH SUNDAY/...
MVFR/IFR PERSISTS THIS AFTERNOON ACROSS WESTERN NEW YORK WITHIN RAIN
SHOWERS AND LOW CIGS. THIS IS ALL A RESULT OF A LOW PRESSURE SYSTEM
CENTERED NEAR DTX. A LEADING BAND OF SHOWERS WHICH HAS SHIFTED EAST
OF KBUF/KIAG/KJHW WILL SHIFT ACROSS KROC/KART THIS AFTERNOON.

BEHIND THIS LEADING BAND OF ORGANIZED RAIN SHOWERS...OCCASIONAL
SCATTERED TO NUMEROUS SHOWERS WILL BE FOUND INTO TONIGHT AS THE
SURFACE AND UPPER LEVEL LOW PIVOT ACROSS THE CENTRAL AND EASTERN
GREAT LAKES. THIS WILL CONTINUE MVFR CIGS ACROSS ALL SITES EXCEPT
KJHW WHERE IFR IS EXPECTED TO PERSIST IN THE HIGHER TERRAIN.

A FRESH SHOT OF COLD AIR WILL WORK ACROSS THE REGION ON WEDNESDAY
CHANGING RAIN SHOWERS TO A MIX OF RAIN AND SNOW SHOWERS THEN
EVENTUALLY ALL SNOW SHOWERS THROUGH WEDNESDAY. THIS WILL KEEP AT
LEAST MVFR WITH IFR A THREAT WHERE SNOW BEGINS MIXING IN.

OUTLOOK...
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.
SUNDAY...VFR/MVFR WITH A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
LIGHT EASTERLY WINDS WILL VEER TO SOUTHERLY THROUGH THIS EVENING AS
A WARM FRONT LIFTS ACROSS THE REGION. THE ASSOCIATED LOW
PRESSURE SYSTEM WILL PIVOT ACROSS THE LOWER GREAT LAKES TONIGHT WITH
A COLD FRONT THEN BRINGING WIDESPREAD ADVISORY WINDS AND WAVES LATER
TONIGHT THROUGH THURSDAY NIGHT. GIVEN HIGH CONFIDENCE IN THESE
HIGHER WINDS AND WAVES SMALL CRAFT ADVISORIES ARE ISSUED 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/SMITH
NEAR TERM...CHURCH/SMITH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...CHURCH/SMITH
MARINE...CHURCH/SMITH







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.