Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 280444
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1144 PM EST THU NOV 27 2014

.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL TRACK ACROSS THE EASTERN GREAT LAKES
REGION TONIGHT...AND BRING ACCUMULATING SNOW SHOWERS...WITH HIGHEST
ACCUMULATIONS ACROSS THE HILLS OF WESTERN NEW YORK...AND TO THE
SOUTHEAST OF LAKE ONTARIO. COLD TEMPERATURES WILL CONTINUE THROUGH
FRIDAY BEFORE BECOMING NOTICEABLY MILDER FOR SATURDAY AND THROUGH
THE REMAINDER OF THE HOLIDAY WEEKEND. THERE WILL BE CHANCES FOR
LIGHT RAIN AND WET SNOW SHOWERS EACH WEEKEND DAY.

&&

.NEAR TERM /THROUGH FRIDAY/...
AT 1130 PM...RADAR SHOWS A CLUSTER OF LAKE ENHANCED SNOW SHOWERS
ACROSS FAR WESTERN NEW YORK...WITH THE BACK EDGE AT NIAGARA FALLS.
SNOW SHOWERS SHOULD END FROM NORTHWEST TO SOUTHEAST ACROSS THE
NIAGARA FRONTIER...TAPERING OFF AROUND MIDNIGHT IN THE BUFFALO
METRO AREA.

ELSEWHERE...SNOW SHOWERS HAVE PICKED UP IN INTENSITY ACROSS
WESTERN PORTIONS OF THE SOUTHERN TIER AND THE BOSTON/WYOMING
HILLS...AS THE SHORTWAVE AND A WIND SHIFT TO THE NORTHWEST
SQUEEZES OUT LAKE ENHANCED MOISTURE. SNOW SHOWERS WILL LINGER A
BIT LONGER HEAR DUE TO LAKE INFLUENCES...WITH THE GREATEST
ACCUMULATIONS ACROSS HIGHER TERRAIN IN THESE AREAS.

OTHERWISE...COLD AIR ALOFT WILL CONTINUE TO PUSH ACROSS THE LAKES
WITH TEMPERATURES AT 850 HPA DROPPING TO -15C. THIS WILL INCREASE
LOW LEVEL LAPSE RATES AND A MODEST INCREASE IN LAKE INDUCED
EQUILIBRIUM LEVELS SHOULD A LAKE EFFECT RESPONSE. THE WNW FLOW
DOWN THE LENGTH OF LAKE ONTARIO HAS THE BEST CHANCE TO ORGANIZE
INTO A SINGULAR BAND AND PRODUCE THE GREATEST SNOWFALL AMOUNTS.
IF THIS OCCURS...IT WOULD BE AROUND DAYBREAK FRIDAY MORNING WHEN
WIND FIELDS ARE BEST ALIGNED. IF THIS DOES OCCUR...THERE WOULD BE
A COUPLE HOURS OF HEAVY SNOW SOUTHEAST OF LAKE ONTARIO...BUT THIS
BAND WOULD BE RELATIVELY SHORT LIVED AS WINDS SHIFT TO THE WEST
LATE MORNING WHICH WOULD LIFT THE BAND NORTHWARD AND LIMIT
SNOWFALL TOTALS. BEFORE THIS...DISORGANIZED LAKE EFFECT AND
MOISTURE WITH THE SHORTWAVE WILL BRING A MORE GENERAL LIGHT
SNOWFALL SOUTHEAST OF THE LAKE. TOTALS STILL LOOK TO BE IN THE
ADVISORY RANGE...BUT IT WILL BE CLOSE.

AS THE FLOW PASSES OVER THE LONG FETCH OF LAKE ONTARIO THERE MAY
BE A BRIEF UPTICK IN SNOW INTENSITY TOMORROW AFTERNOON FOR THE TUG
HILL REGION. ALSO...SOUTHWEST WINDS SHOULD LIFT WHAT IS LEFT OF
THE BAND BACK INTO THE BUFFALO METRO AREA LATE FRIDAY AFTERNOON.
ANY ACCUMULATIONS SHOULD BE LIGHT...BUT STILL ENOUGH TO MAKE ROADS
SLICK IN SPOTS.

TEMPERATURES TONIGHT WILL BE A BIT COOLER THAN LAST NIGHT WITH LOWS
IN THE UPPER TEENS TO MID 20S. HIGHS UNDER THE -13 TO -14C AIRMASS
AT 850 HPA WILL ONLY RECOVER INTO THE MID TO UPPER 20S.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
RETURN FLOW OF MILDER AND MOIST AIR SETTING UP FRIDAY NIGHT AS HIGH
PRESSURE SLIDE EAST OFF THE ATLANTIC COAST. ONGOING LAKE EFFECT
SNOWS EAST OF THE LAKES WILL GRADUALLY DIMINISH AS THIS WARM AIR
ADVECTION PATTERN OVERWHELMS THE AREA. A GENERAL LIGHT SNOW SHOULD
DEVELOP AHEAD OF THE APPROACHING WARM FRONTAL BOUNDARY LATE FRIDAY
NIGHT INTO THE FIRST HALF OF SATURDAY. LATEST MODELS SUGGESTING THAT
THE PRIMARY ISENTROPIC ASCENT WILL FOCUS NORTH AND WEST OF THE AREA
SIGNALING ONLY LIGHT AMOUNTS EXPECTED FOR WESTERN AND NORTH CENTRAL
NEW YORK.

BROAD WARM AIR ADVECTION PATTERN WILL REMAIN ACROSS THE AREA FOR THE
REMAINDER OF THE PERIOD AHEAD OF APPROACHING COLD FRONT. THOUGH ANY
FORCING MECHANISMS LOOKING RATHER WEAK AND DIFFUSE THERE COULD BE A
FEW SPOTTY SHOWERS DEVELOPING WITHIN WARM AIR ADVECTION PATTER.

SHARP WARMING TREND ON TAP FOR THE WEEKEND...WITH STRONG AND DEEP
SOUTHWEST FLOW DEVELOPING. 925 MB TEMPS PROGGED TO SURGE TO NEAR +8C
BY SUNDAY AHEAD OF THE COLD FRONT...MAKING A RUN SOLIDLY INTO THE
50S LIKELY.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
COLD FRONT CROSSING THE AREA MONDAY SHOULD BRING A BAND OF
PRECIPITATION WITH IT. CRITICAL TEMPERATURES SUGGEST RAIN SHOWERS
AHEAD OF THE BOUNDARY WITH A TRANSITION OVER TO SNOW BEHIND IT AS
STRONG COLD AIR ADVECTION DEVELOPS.

THERE SHOULD BE A BRIEF OPPORTUNITY FOR SOME LAKE ENHANCEMENT ON A
SHORT NORTHERLY FETCH ALONG THE SOUTH SHORE OF LAKE ONTARIO LATE
MONDAY AND MONDAY NIGHT. HOWEVER THIS SHOULD QUICKLY END ALTOGETHER
BY TUESDAY MORNING AS STRONG SURFACE BASED RIDGING AND ATTENDANT
DRYING/SUBSIDENCE BUILDS ACROSS THE LOWER GREAT LAKES.

THE AREA OF HIGH PRESSURE WILL PROVIDED A FAIR AND DRY TUESDAY
ALTHOUGH IT WILL BE BRIEF. THE HIGH LOOKS TO SHIFT OFF TO THE EAST
QUICKLY...SETTING UP MOIST AND WARM AIR ADVECTION PATTERN WITH
PRECIPITATION LIKELY TO BREAK OF TUESDAY NIGHT INTO WEDNESDAY.

CONFIDENCE IS LOW ON PRECIPITATION TYPE AT THIS STAGE OF THE
FORECAST WITH MEDIUM RANGE GUIDANCE NOT IN AGREEMENT ON THERMAL
PROFILES. THIS PERIOD WILL NEED TO BE MONITORED WITH AT LEAST SOME
POTENTIAL FOR ICING.

ANOTHER SURGE OF FRESH ARCTIC AIR SPREAD ACROSS THE LOWER LAKES
BEHIND THE PASSAGE OF A COLD FRONT LATER WEDNESDAY INTO THURSDAY.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT 04Z...A SHORTWAVE WAS MOVING ACROSS THE REGION RESULTING IN
LAKE ENHANCED SNOW SHOWERS. CONDITIONS WILL VARY SIGNIFICANTLY IN
AND OUT OF LAKE EFFECT SNOW SHOWERS. THE STEADIEST SNOW SHOWERS
ARE LIKELY TO BE AT JHW...WHERE MOISTURE ASSOCIATED WITH A
SHORTWAVE CONTINUES TO DROP SOUTHEASTWARD...AND UPSLOPING AND LAKE
MOISTURE ENHANCE LOW LEVEL MOISTURE. CONDITIONS SHOULD IMPROVE
LATE TONIGHT OUTSIDE OF SNOW SHOWERS...WITH MAINLY VFR CONDITIONS
IN MOST AREAS BY FRIDAY MORNING. ANY LINGERING LAKE EFFECT SNOW
BANDS WILL LIFT NORTH...AND MAY CLIP BUF/ART AROUND 00Z SATURDAY.

OUTLOOK...
FRIDAY NIGHT...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS WITH
IFR/MVFR CONDITIONS EAST OF THE LAKES.
SATURDAY THROUGH MONDAY...MAINLY VFR WITH A CHANCE OF RAIN AND
SNOW SHOWERS.
TUESDAY...VFR

&&

.MARINE...
AN UPPER LEVEL DISTURBANCE WILL CROSS THE EASTERN GREAT LAKES
TONIGHT WITH COLD AIR FRESHENING IN ITS WAKE. THIS COLD AIR COMBINED
WITH MODEST WESTERLIES WILL BRING SMALL CRAFT ADVISORIES FOR THE
EASTERN GREAT LAKES...FIRST ON LAKE ERIE THIS EVENING AND THEN
THROUGH THE OVERNIGHT ON LAKE ONTARIO. WARMING COMMENCING FRIDAY
EVENING AND OVERNIGHT WILL WEAKEN LAPSE RATES...AND THIS COMBINED
WITH THE EFFECTS OF HIGH PRESSURE EXPANDING TOWARDS THE LAKES WILL
ALLOW FOR WINDS TO BECOME LIGHT...AND ADVISORIES ENDING.

SOUTHWEST WINDS SATURDAY AND SATURDAY NIGHT MAY BRING LOW END SCA
FOR LAKE ERIE AND THE EASTERN SHORELINE OF LAKE ONTARIO.

&&

.CLIMATE...
AFTER AN EXTENDED PERIOD OF COLD DURING THE MIDDLE OF NOVEMBER IT
APPEARS TEMPERATURES WILL AVERAGE ABOVE NORMAL MOST OF THE TIME OVER
THE NEXT FEW WEEKS. THERE WILL BE BRIEF PUSHES OF COLDER AIR AT
TIMES AS PROGRESSIVE TROUGHS AMPLIFY INTO THE GREAT LAKES...BUT
THESE COLD PERIODS WILL BE SHORT LIVED...ONLY LASTING FOR A FEW DAYS
AT A TIME...AND WILL BE OUTNUMBERED BY MILD DAYS.

LOOKING AT THE HEMISPHERIC PATTERN...A POSITIVE NORTH ATLANTIC
OSCILLATION /NAO/ WILL PERSIST INTO THE FIRST FEW DAYS OF DECEMBER
BASED ON THE GEFS ENSEMBLE MEAN. THE MEAN LONGWAVE TROUGH OVER THE
NORTH ATLANTIC IN SUCH A PATTERN WILL PREVENT ANY COLD FROM LOCKING
IN OVER THE NORTHEAST QUARTER OF THE UNITED STATES. THE PACIFIC
NORTH AMERICAN PATTERN /PNA/ WILL REMAIN NEGATIVE THROUGH THE FIRST
FEW DAYS OF DECEMBER...BEFORE TRENDING POSITIVE BASED ON GEFS
ENSEMBLE MEMBERS. THIS TOO WILL PREVENT COLD FROM LOCKING INTO THE
NORTHEAST FOR MORE THAN A FEW DAYS AT A TIME.

THE MADDEN JULIAN OSCILLATION /MJO/ MAY PLAY AN IMPORTANT ROLE IN
DRIVING PATTERN CHANGE THROUGH MID DECEMBER. ANALYSIS OVER THE PAST
WEEK HAS SHOWN A MODERATELY STRONG MJO EVENT DEVELOPING OVER THE
INDIAN OCEAN. A GEFS ENSEMBLE FORECAST OF THE WHEELER PHASE/SPACE
PLOT SHOWS THIS MJO ORBITING THROUGH PHASE 4 AND 5 DURING THE FIRST
WEEK IN DECEMBER AS CONVECTION MOVES EAST ACROSS THE MARITIME
CONTINENT. A LOOK AT COMPOSITE CHARTS OF PAST EVENTS FAVORS ABOVE
NORMAL TEMPERATURES ACROSS MUCH OF THE CENTRAL AND EASTERN UNITED
STATES DURING PHASE 4 THROUGH 6 OF THE MJO.

EVENTUALLY AS WE GET INTO THE SECOND WEEK IN DECEMBER MJO CONVECTION
WILL CONTINUE ITS EASTWARD ORBIT THROUGH THE PACIFIC AND INTO THE
WESTERN HEMISPHERE. IF THE MJO CONVECTION PERSISTS ON ITS EASTWARD
JOURNEY AND REACHES PHASE 7 OF THE WHEELER PHASE/SPACE PLOT...IT
WOULD FAVOR A SIGNIFICANT PATTERN CHANGE TOWARDS COLDER THAN NORMAL
TEMPERATURES OVER THE CENTRAL AND EASTERN UNITED STATES. THE MJO
ACCOMPLISHES THIS AS SUB-TROPICAL CONVECTION INFLUENCES THE PATTERN
OVER THE PACIFIC...FORCING AMPLIFICATION OF THE EASTWARD EXTENSION
OF THE EAST ASIAN JET WHICH IN TURN FORCES DOWNSTREAM AMPLIFICATION
OF THE PATTERN ACROSS NORTH AMERICA. BASED ON THE FORECAST TIMING OF
THE MJO EPISODE THIS WOULD MOST LIKELY OCCUR BY WEEK 2 OR 3 OF
DECEMBER AND FEED BACK INTO MORE HIGH LATITUDE BLOCKING AND MORE
LONG LASTING COLD.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR NYZ004>006.
     LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST FRIDAY FOR NYZ012-019-
     020-085.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST FRIDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 4 AM FRIDAY TO 1 AM EST
         SATURDAY FOR LOZ043-044.
         SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM 7 AM FRIDAY TO 1 AM EST SATURDAY
         FOR LOZ045.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
CLIMATE...HITCHCOCK







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