FXUS61 KBUF 301813
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
113 PM EST MON NOV 30 2009

.SYNOPSIS...
A NORTHWEST FLOW OF COLDER AIR BEHIND THE PASSAGE OF A COLD FRONT 
EARLY THIS MORNING WILL OVERSPREAD THE REGION TODAY AS HIGH PRESSURE 
BUILDS EAST FROM THE CENTRAL GREAT LAKES AND OHIO VALLEY THIS 
AFTERNOON. A TROUGH OVER THE CENTRAL LAKES LATE TONIGHT IS EXPECTED 
TO MOVE EAST AND BRING A THREAT OF PRECIPITATION LATE TONIGHT AND 
TUESDAY THAT WILL BE ENHANCED NEAR LAKE ERIE AND EAST OF LAKE 
ONTARIO. A WARM FRONT OVER THE LOWER LAKES EARLY WEDNESDAY WILL LIFT 
NORTH OF LAKE ONTARIO WEDNESDAY AFTERNOON.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS WILL BE A TRANSITION PERIOD WITH SOME IMPORTANT LAKE EFFECT 
CONSIDERATIONS BEFORE DAYBREAK TUESDAY.

HAVE ISSUED A LAKE EFFECT SNOW ADVISORY FOR MUCH OF THE NIAGARA 
FRONTIER AND LAKE SHORE AREA OF CHAUTAUQUA COUNTY AS THE LASTEST 12Z 
NAM/WRF IS IN AGREEMENT WITH SEVERAL LOCALLY RUN 6KM MESOSCALE 
MODELS (INCL REGIONWIDE MESOSCALE ENSEMBLE) THAT A BAND OF MODERATE 
TO POTENTIALLY HEAVY ALKE EFFECT SNOW WILL DEVLEOP OVER LAKE ERIE 
LATER TONIGHT AND EXTEND ACROSS PARTS OF THE NIAGARA FRONTIER.

H85 TEMPS OF -6C SHOULD BE JUST COLD ENOUGH TO INTERACT WITH A LAKE 
SFC OF 8C TO ALLOW FOR LAKE INDUCED CONVECTION LATER TONIGHT...AND 
WITH A FAIRLY WELL ALIGNED SOUTHWEST FLOW AND A LAKE INDUCED 
EQUILIBRIUM LEVEL OVER 10K FT...A WELL DEFINED BAND OF MODERATE TO 
HEAVY LAKE SNOW IS EXPECTED TO EXTEND ACROSS THE BUF METRO AREA. THE 
BAND IS EXPECTED TO BE MOST ORGANIZED BETWEEN ABOUT 4 AM AND 9 AM IN 
THE VICINITY OF THE BUF METRO AREA...THEN AS THE FLOW VEERS TO W/NW 
AFTER 9 AM...THE ACTIVITY WILL SHIFT WELL SOUTH OF BUFFALO. 

THERE WILL BE THE POTENTIAL FOR SOME THUNDER AND LIGHTNING WITHIN 
THE HEART OF THE SNOWBAND...AS FAVORABLE EQUILIBRIUM LEVEL HEIGHTS 
WILL BE ACCOMPANIED BY A -10C LEVEL OF ABOUT 5K FT.

SNOWFALL RATES OF ONE HALF TO ONE INCH PER HOUR WILL BE LIKELY UNDE 
THE BAND...AND WITH THE STEADIEST ACTIVITY EXPECETD DURING THE 
MORNING RUSH HOUR...MOTORISTS SHOULD BE PREPARED FOR A SLOW AND 
POTENTIALLY TRICKY COMMUTE.

SNOWFALL AMOUNTS FROM THIS SHORT LIVED EVENT WILL RANGE FROM 2 TO 4 
INCHES ACROSS THEMAJORITY OF THE NIAGARA FRONTIER...WITH AMOUNTS OF 
3 TO 6 INCHES POSSIBLE ACROSS MUCH OF NORTHERN ERIE...SOUTHERN 
NIAGARA...WESTERN GENESEE COUNTY...AND THE CHAUTAUQUA COUNTY LAKE 
SHORE.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
TUESDAY, THE SFC TROUGH MOVES EAST ACROSS THE AREA IN THE MORNING. 
WINDS WILL BE SW ENOUGH AHEAD OF THE TROUGH IN THE MORNING TO BRING 
SOME LK ENHANCED SNOW TO THE BUF METRO AREA TUESDAY MORNING THEN 
THEY SHOULD BECOME A BIT MORE WESTERLY BEHIND THE TROUGH AFT 15Z OR 
SO AND PUSH MOST OF THE PRECIP SOUTH OF THE METRO AREA WHERE IT SHLD 
WEAKEN IN THE AFTERNOON AS BUFKIT PROFILES SHOW THE INVERSION 
CRASHING DURG THE COURSE OF THE AFTERNOON. ANOTHER INCH OR TWO OF 
SNOW IS POSSIBLE IN THE MORNING IN THE BUFFALO METRO AREA TO BATAVIA 
BEFORE IT MOVES SOUTH WITH ANOTHER INCH OR TWO ACROSS THE HILLS 
SOUTH OF BUFFALO TO THE SOUTHERN TIER. SOME OF THE LAKE ENHANCED 
PRECIP OFF LK ERIE IS EXPECTED TO GET AS FAR EAST AS THE ROCHESTER 
AREA. WILL CARRY LKLY POPS EAST TO THE ROC AREA IN THE MORNING WHERE 
THEY COULD GET A COATING TO LESS THAN AN INCH

BNDRY LYR TEMPS SHLD MODERATE ENOUGH IN THE AFTERNOON FOR ANY PRECIP 
TO BE MNLY RAIN EXCEPT FOR A PSBL MIX STILL ACROSS THE HIGHEST 
TERRAIN OF THE SOUTHERN TIER. 

EAST OF LK ONTARIO, THE MM5 SHOWS THE SITUATION SHLD BE SIMILAR WITH 
THE ACTIVITY BEING ENHANCED NE OF THE LK FRM ART NORTHWARD THROUGH 
18Z AND THEN THAT AREA WEAKENING WITH ANOTHER DEVELOPING FURTHER 
SOUTH AROUND OSWEGO COUNTY FRM ARND 18Z-21Z AND THEN SETTLING SOUTH 
INTO SOUTHERN OSWEGO AND NORTHERN CAYUGA COUNTY BY EVENING. THE 
SYR PROFILE SHOWS THE INVERSION LOWERING RAPIDLY TUES NGT.
 
BNDRY LYR TEMPS SHLD WARM ENOUGH FOR RAIN OR RAIN/SNOW MIX BY MIDDAY 
AND AFTERNOON ACROSS LOWER ELEVATIONS. SNOW ACCUMS OF AN INCH OR TWO 
ARE POSSIBLE. HIGHS TUESDAY SHLD GENLY RANGE FROM THE UPPER 30S TO 
LOWER 40S.

WILL CONTINUE CHC POPS TUESDAY NIGHT ACROSS PORTIONS OF THE 
EASTERN LK ONTARIO REGION SOUTH OF WATERTOWN MNLY FROM THE SOUTHERN 
TWO THIRDS OF LEWIS COUNTY SOUTH TO NORTHERN CAYUGA AND NORTHEAST 
PORTIONS OF WAYNE COUNTY. ELSEWHERE UPPER RIDGING...SOUTHWESTERLY 
WINDS AND WARMING WILL BRING AN END TO THE LAKE EFFECT AND BRING 
PARTIAL CLEARING TUESDAY NIGHT TO AREAS SOUTH OF THE THRUWAY.

LOWS TUESDAY NGT SHLD RANGE FROM 25 TO 30 ACROSS THE SOUTHERN TIER 
AND ACROSS AREAS EAST OF LK ONTARIO TO LOWER 30S ACROSS THE FINGER 
LKS AND NIAGARA FRONTIER.

ON WEDNESDAY AS A WARM FRONT LIFTS NORTH OF LAKE ONTARIO WE SHLD SEE 
A PERIOD OF PTLY TO MSTLY SUNNY SKIES BUT SOME CLOUDS WILL LINGER 
ACROSS THE NORTH COUNTRY EARLY IN THE MORNING DUE TO THE WARM FRONT. 
EXPECT CLOUDS TO INCREASE FROM THE SOUTHERN TIER NORTHWARD DURG THE 
AFTERNOON AS MOISTURE AHEAD OF A STORM SYSTEM OVER THE SOUTHEASTERN 
STATES SPREADS NORTHWARD. AT THIS TIME GOING MORE TWD ECMWF AND AND 
ONLY BRINGING IN LOW CHC OF RAIN LATE IN THE DAY NEAR THE NY/PA 
BORDER. HIGHS WED SHLD REBOUND AGAIN TO THE MID TO UPPER 40S AS THE 
HIGH OFF THE COAST SENDS A SE FLOW OF MILDER AIR NORTHWARD.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A SPLIT FLOW OVER THE EASTERN HALF OF COUNTRY WEDNESDAY MORNING WILL 
PHASE INTO A FAIRLY DEEP LONG WAVE TROUGH OVER THE GREAT LAKES 
REGION BY FRIDAY. THIS WILL RESULT IN A CHANGE TO COLDER...MORE 
SEASONABLE CONDITIONS THAT WILL PERSIST THROUGH THE WEEKEND. THIS 
WILL LIKELY LEAD TO MORE SNOW AS WELL...AND POSSIBLY SOME 
SIGNIFICANT LAKE EFFECT ACTIVITY.

THE CLOSED LOW OVER THE TEXAS/LOWER MISSISSIPPI VALLEY WEDNESDAY IS 
EXPECTED TO OPEN UP BY WEDNESDAY EVENING...WITH A SFC WAVE DEEPENING 
AS IT LIFTS UP ALONG THE SPINE OF THE APPALACHIANS. THIS WILL SEND A 
SURGE OF MOISTURE UP ACROSS THE MID ATLANTIC STATES TO OUR REGION...
ALONG WITH RELATIVELY MILD AIR. HAVE RAISED SFC TEMPS BY SOME 3 TO 6 
DEG F FOR WEDNESDAY NIGHT AS THE GEFS...OPERATIONAL GFS AND ECWMF 
BRING THE SFC LOW UP ACROSS PENNSYLVANIA. WHILE THE ECMWF IS SOME 
100 MILES 'SLOWER' THAN THE GEFS AND OPERATIONAL GFS...IT IS ALSO 
FAVORING A WARM ADVECTION PATTERN ALOFT. THE GEFS MEAN H85 TEMP OVER 
THE FINGER LAKES REGION AT 06Z THURS IS AROND ZERO C WITH FAIRLY 
STRONG WAA EXPECTED FROM THAT POINT INTO THE EARLY DAYLIGHT HOURS OF 
THURSDAY.

AS A RESULT...HAVE BACKED OFF ON THE FROZEN/FREEZING PCPN FOR 
WEDNESDAY NIGHT AND HAVE SIMPLY MADE THE P-TYPE AS RAIN. POPS FOR 
WEDN NIGHT HAVE ALSO BEEN RAISED A LITTLE TO HIGH LIKELY (FROM CHC). 

DURING THE COURSE OF THURSDAY AS THE TWO MAIN JETS PHASE OVER THE 
OHIO VALLEY...A SUB 990MB LOW WILL CONTINUE TO LIFT AND DEEPEN ACROS 
NEW ENGLAND. COLDER AIR ON ITS BACKSIDE WILL POUR ACROSS OUR REGION 
AND CHANGE THE RAIN TO SNOW...WITH BOTH THE ECMWF AND GEFS 
SUGGESTING A PROLONGED DEFORMATION ZONE DRAGGING ACROSS THE BULK OF 
THE REGION. THIS TRAILING MID LEVEL DEFORMATION ZONE WILL BE FROM 
WESTERN TO NORTHERN NEW YORK AND COULD BRING AN ACCUMULATING 
SYNOPTIC SNOW AS ECMWF QPF RANGES NEAR THREE QUARTERS OF AN INCH 
/LIQUID/ WHICH WOULD TRASNLATE INTO SEVERAL INCHES OF SNOW. 

AS THE SURFACE LOW LIFTS NORTHWARD ACROSS WESTERN QUEBEC ON THURSDAY 
NIGHT...THE FLOW ON THE WESTERN SIDE OF THE LOW WILL DRAW MUCH 
COLDER AIR INTO NEW YORK STATE DURING THURSDAY NIGHT...DEEPENING AND 
GETTING COLDER ON FRIDAY. THIS COULD SPELL THE BEGINNING OF A WELL 
DEVELOPED LAKE EFFECT SNOW EVENT WITH 850MB TEMPS FALLING TO A RANGE 
FROM -10C TO -12C BY LATE FRIDAY MORNING.

THE WEEKEND WILL SEE A MORE ZONAL FLOW DEVELOPING BUT 850MB TEMPS 
WILL HOVER AT OR BELOW ZERO THROUGH THE WEEKEND. CHANCE POPS EACH 
DAY WILL OFFER SOME NIGHTTIME SNOW SHOWERS AND DAYTIME RAIN SHOWERS 
OR A RAIN/SNOW MIX AT HIGHER ELEVATIONS.

COLDER TEMPS ARE EXPECTED THROUGH THE REST OF THE WEEK WITH LOWS IN 
THE MID TO UPPER 20S AND HIGHS ONLY IN THE MID TO UPPER 30S. THE 
WEEKEND MAY SEE A MODERATING TREND WITH HIGHS IN THE UPPER 30S TO 
NEAR 40 ON SATURDAY AND TO THE LOWER 40S ON SUNDAY.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A CHILLY WEST TO NORTHWEST FLOW ACROSS LAKES ERIE AND ONTARIO WILL 
PRODUCE MVFR CIGS (2500 FT) FOR PORTIONS OF THE REGION THIS 
AFTERNOON...INCLUDING KJW...KROC AND KART. OTHERWISE...VFR CIGS WILL 
BE IN PLACE ACROSS THE REGION THROUGH THE FIRST HALF OF TONIGHT WITH 
GENERALLY LIGHT WINDS.

LATER TONIGHT...A SIGNIFICANT BAND OF LAKE EFFECT SNOW WILL DEVELOP 
OFF LAKE ERIE. THIS BAND WILL EXTEND ACROSS THE NIAGARA FRONTIER 
DURING THE WEE HOURS OF TUESDAY MORNING AND WILL PERSIST THROUGH THE 
MORNING RUSH HOUR BEFORE SHIFTING WELL SOUTH OF BUFFALO. THIS WILL 
RESULT IN LIFR CONDITIONS IN REDUCED CIGS/VSBYS FOR KIAG AND 
PARTICULARLY KBUF WHERE SIGNIFICANT DELAYS TO COMMERCIAL AVIATION 
WILL BE LIKELY.

MVFR CONDITIONS WILL BE FOUND AT BOTH KROC AND KJW TUESDAY MORNING 
AS A RESULT OF THE SHIFTING LAKE BANDS...WITH CONDITIONS 
DETERIORATING TO IFR AT KJHW BY MIDDAY. LAKE ENHANCED SNOWS WILL 
ALSO LIKELY REDUCE VSBYS AND CIGS TO MVFR LEVELS AT KART.

OUTLOOK...
TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...VFR.
WEDNESDAY NIGHT/THURSDAY ...MVFR/IFR IN RAIN. LOW LEVEL WIND SHEAR 
LIKELY.
FRIDAY AND SATURDAY...MVFR. SCATTERED SNOW SHOWERS. LOCAL IFR/LIFR 
IN LAKE EFFECT SNOW EAST OF LAKES ERIE AND ONTARIO.

&&

.MARINE...
GUSTY WINDS IN THE WAKE OF A COLD FRONT WILL PRODUCE WAVES OF FOUR 
FEET OR MORE ACROSS THE NEARSHORE WATERS OF LAKE ONTARIO FROM THE 
NIAGARA RIVER TO MEXICO BAY THROUGH EARLY AFTERNOON. HAVE THUS 
RAISED SMALL CRAFT ADVISORIES FOR THESE NEARSHORE WATERS THROUGH 
19Z.

MEANWHILE...A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR THE 
NEARSHORE WATERS OF LAKE ERIE LATER TONIGHT THROUGH TUESDAY 
AFTERNOON. A VIGOROUS AREA OF LOW PRESSURE WILL DROP ACROSS SOUTHERN 
ONTARIO LATER TONIGHT...WITH WINDS BECOMING SOUTHWESTERLY AND 
INCREASING TO 15 TO 25 KNOTS BY DAYBREAK TUESDAY. THESE WINDS WILL 
CONTINUE TO INCREASE TO 30 KNOTS FOR MUCH OF TUESDAY MORNING BEFORE 
GRADUALLY SUBSIDING TUESDAY AFTERNOON AND EVENING.

&&

.CLIMATE...
STILL NO MEASURABLE SNOW SO FAR THIS SEASON OVER MOST OF WESTERN NEW 
YORK. WE ARE ALREADY OVER THREE WEEKS LATE (NORMAL DATES ARE NOV 7 
FOR BUFFALO AND NOV 8 FOR ROCHESTER). WE WILL AT LEAST GET THROUGH
TODAY...SO THIS WILL BE THE LATEST IN 63 YEARS (1946) AT BUFFALO...
AND LATEST IN 46 YEARS (1963) AT ROCHESTER. THE ALL TIME RECORD
LATEST DATES FOR FIRST MEASURABLE SNOW ARE DEC 3 1899 AT BUFFALO
AND DEC 10 1948 AT ROCHESTER.

IN ADDITION, ITS BEEN A LONG TIME SINCE EITHER BUFFALO OR ROCHESTER 
LAST SAW MEASURABLE SNOW. THROUGH YESTERDAY NOV 29...BUFFALO HAS GONE
236 DAYS WITHOUT MEASURABLE SNOW, OR SINCE APRIL 7, 2009. THIS IS
THE 4TH LONGEST STRETCH IN 125 YEARS OF RECORDS. THE RECORD IS 277
DAYS SET BACK IN 1946. ROCHESTER IS ALSO AT 236 DAYS WITHOUT
MEASURABLE SNOW, OR THE 3RD LONGEST STRETCH THERE. THE RECORD IS
260 DAYS SET BACK IN 1952.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY FROM 1 AM TO NOON EST TUESDAY FOR 
     NYZ001-010-011-019-085.
MARINE...SMALL CRAFT ADVISORY FROM 3 AM TO 4 PM EST TUESDAY FOR LEZ020-
         040-041.
         SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON 
         FOR LOZ042>044.

&&

$$

SYNOPSIS...JJP
NEAR TERM...RSH
SHORT TERM...JJP
LONG TERM...JJP/RSH/WCH
AVIATION...RSH
MARINE...RSH
CLIMATE...TMA/SAGE