Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 272328
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
628 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 600 PM...RADAR SHOWS A CLUSTER OF SNOW SHOWERS DEVELOPING NEAR
THE NIAGARA RIVER IN ADVANCE OF AN APPROACHING SHORTWAVE.
MESOSCALE GUIDANCE (NAM/ARW/WRF/HRRR) ALL CAPTURE THIS...BUT
DIFFER ON ITS LOCATION. NOW THAT IT HAS DEVELOPED...EXPECT THAT IT
WILL CONTINUE TO TRACK SOUTHEAST ACROSS THE NIAGARA FRONTIER
BEFORE WEAKENING. THIS SHOULD BRING 1 TO 3 INCHES OF SNOW TO THE
NORTH TOWNS...NIAGARA FALLS...BATAVIA...NORTHWARD TO THE SOUTH SHORES OF
LAKE ONTARIO. FORECAST WAS UPDATED TO ACCOUNT FOR THIS MESOSCALE EFFECT.

OTHERWISE...SNOW SHOWERS ARE MOVING INTO THE ADVISORY AREA IN SOUTHWESTERN
NEW YORK AS EXPECTED. WATER VAPOR IMAGERY DISPLAYS A LONG WAVE
TROUGH OVER THE EASTERN US WITH AN EMBEDDED SHORTWAVE APPROACHING
OUR REGION. AT THE SURFACE A WEAK W-E TROUGH IS FOUND NEAR LAKE
ONTARIO WITH WINDS VEERED MORE NORTHWESTERLY ON THE NORTHERN
SIDE...AND WESTERLY ON THE SOUTHERN SIDE OF THE TROUGH.

FOR TONIGHT LIFT AHEAD OF THIS SHORTWAVE...COMBINED WITH THE WEAK
SURFACE CONVERGENCE WILL BRING A PERIOD OF LIGHT SNOW ACROSS THE
REGION...ESPECIALLY SOUTH OF LAKE ONTARIO. ALOFT COLD AIR WILL PUSH
ACROSS THE LAKES WITH TEMPERATURES AT 850 HPA DROPPING TO -14C. THIS
WILL INCREASE LOW LEVEL LAPSE RATES AND A MODEST INCREASE IN LAKE
INDUCED EQUILIBRIUM LEVELS SHOULD A LAKE EFFECT RESPONSE. THIS
RESPONSE WILL HEIGHTEN THE SNOWFALL ACROSS SKI COUNTRY AND THE
SOUTHERN TIER FOR WHICH A LAKE EFFECT SNOW ADVISORY WILL BE IN PLACE
OVERNIGHT. THIS BAND OF SNOW WILL WEAKEN SOME TOWARDS MORNING AS
DRIER AIR ASSOCIATED WITH HIGH PRESSURE FILTERS INTO THE LAKE EFFECT
SNOW BAND. BACKING WINDS WILL TAKE THIS WEAKENING SNOWBAND NORTHWARD
TOWARDS THE CITY OF BUFFALO BY FRIDAY AFTERNOON.

SIMILARLY AS THE COLD AIR DEEPENS ACROSS LAKE ONTARIO LAKE EFFECT
SNOW SHOULD BECOME PREDOMINATE LATER OVERNIGHT BEHIND THE UPPER
LEVEL SHORTWAVE. A NORTHWEST FLOW WILL INITIALLY ALIGN THE BAND
ACROSS AREAS SOUTHEAST OF LAKE ONTARIO...WITH THE BAND SLOWLY
TURNING ITS FOCUS TOWARDS THE TUG HILL REGION FRIDAY AFTERNOON AS
SURFACE WINDS BACK ON THE PERIPHERY OF A SOUTHEAST RIDGE OF HIGH
PRESSURE. 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.

TAKING A LOOK AT LATE TONIGHT...THERE IS SOME CONCERN THAT THE
BAND MAY BRIEFLY INTENSIFY AS GUIDANCE HINTS AT THE DEVELOPMENT OF
A CONVERGENCE BAND TOWARD DAYBREAK SOUTHEAST OF LAKE ONTARIO. THIS
MAY BRING A FEW HOURS OF MODERATE TO HEAVY SNOWS TO SOME
LOCATIONS...BUT A RELATIVELY TRANSIENT BAND SHOULD LIMIT
ACCUMULATIONS TO SOME EXTENT BUT THE AREA BEARS WATCHING.

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 /00Z FRIDAY THROUGH TUESDAY/...
AT 23Z...A SHORTWAVE WAS APPROACHING THE REGION FROM THE UPPER
LAKES WITH THIS DISTURBANCE ALREADY ENHANCING LAKE EFFECT SNOW
SHOWERS. CONDITIONS WILL LARGELY DEPEND ON THIS LAKE
ENHANCEMENT...WITH THE WORST CONDITIONS EXPECTED TO BE THIS EVENING
FOR MOST AREAS.

FOR BUF/IAG A CLUSTER OF SNOW SHOWERS WILL BRIEFLY LOWER VSBY TO
1SM OR LESS AT TIMES...BUT CONDITIONS SHOULD IMPROVE LATE THIS
EVENING. A CLUSTER OF SNOW SHOWERS WILL ALSO IMPACT ART DURING THE
SAME TIME PERIOD. STEADIER SNOWS AND LOWER CIGS SHOULD MOVE INTO
JHW AROUND 01Z TO 05Z...WHILE ROC SHOULD ONLY BE BRIEFLY IMPACTED
BY ANY SNOW SHOWERS. THE VARIABLE NATURE OF THE CONDITIONS WILL
MAKE TAFS CHALLENGING...WITH BRIEFLY WORSE (OR BETTER) CONDITIONS
POSSIBLE AT TIMES.

EXPECT CONDITIONS TO IMPROVE LATE TONIGHT AND FRIDAY...WITH
MVFR/VFR CIGS.

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 FROM MIDNIGHT TONIGHT TO 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...THOMAS
CLIMATE...HITCHCOCK







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