Issued by NWS Buffalo, NY
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000 FXUS61 KBUF 242338 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 638 PM EST TUE NOV 24 2009 .SYNOPSIS... A SOUTHERLY FLOW OF MILD AND RELATIVELY MOIST AIR WILL CONTINUE ACROSS WESTERN AND CENTRAL NEW YORK THROUGH THANKSGIVING DAY. THERE WILL BE THE RISK OF A FEW SHOWERS WEDNESDAY AFTERNOON AND AGAIN LATER ON THURSDAY BUT IT WILL BE DRY MOST OF THE TIME. COMPLEX LOW PRESSURE WILL DEVELOP OVER SOUTHERN ONTARIO AND LAKE ERIE THURSDAY NIGHT AND DEEPEN AS IT MOVES EAST AND OFF THE NEW ENGLAND COAST BY EARLY SATURDAY. THIS WILL RESULT IN AN INCREASING CHANCE OF RAIN THURSDAY NIGHT WHICH MAY TURN TO WET SNOW OVER HIGHER ELEVATIONS BY FRIDAY MORNING. COLDER AIR WILL FOLLOW FRIDAY AND SATURDAY WITH DIMINISHING PRECIPITATION. && .NEAR TERM /THROUGH WEDNESDAY/... A SEASONABLY COOL AND MOIST PATTERN HAS SETTLED OVER THE EASTERN THIRD OF THE NATION. HIGH PRESSURE HAS MOVED EASTWARD TO THE CANADIAN MARITIME PROVINCES AND LOW PRESSURE S ESTABLISHED OVER THE NATION`S MIDSECTION. THE BROAD SOUTH/SOUTHEASTERLY FLOW BETWEEN THESE SYSTEMS WILL MAINTAIN THE LOW TO MIDDLE LEVEL MOISTURE ACROSS THE REGION. LINGERING DRIZZLE WEST OF SYRACUSE SHOULD COME TO AN END...ONLY LINGERING IN A FEW SPOTS INTO THIS EVENING. PATCHY FOG MAY DEVELOP LATE THIS EVENING AND TONIGHT...DEPENDING ON BREAKS IN THE CLOUD COVER...AND IF WINDS AT THE SURFACE CAN GO CALM. BEST CHANCE FOR FOG LOOKS TO BE IN THE SOUTHERN TIER. A WEAK WARM/STATIONARY FRONT FROM CENTRAL PA TO WEST CENTRAL NY WILL KEEP THE CHANCE OF LIGHT SHOWERS OR DRIZZLE OVER THE CENTRAL AND WESTERN SOUTHERN TIER TO THE SOUTHWESTERN FINGER LAKES THROUGH THE OVERNIGHT HOURS. THE NEXT PRECIP PATTERN WILL ARRIVE ON WEDNESDAY AS THE PLAINS TROUGH MOVES TO THE MIDWESTERN STATES AND LIFTS BETTER LOW TO MID LEVEL FORCING INTO THE FORECAST AREA FROM THE WEST AND SOUTH. WILL HAVE POPS INCREASE FROM CHANCE IN THE MORNING TO LIKELY POPS IN THE WEST WITH CHANCE POPS OVER THE CENTRAL AND NORTHERN ZONES. TEMPS TONIGHT WILL BENEFIT FROM THE OVERCAST SKIES WITH LOWS IN THE LOWER 40S OVER MOST OF REGION...THEN UPPER 30S FOR THE EASTERN LAKE ONTARIO REGION. HIGHS ON WEDNESDAY WILL REBOUND TO UPPER 40S TO LOW 50S. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... THIS PERIOD BEGINS WITH A SHOWER THREAT AS AN INITIAL UPPER LEVEL SHORT WAVE SLIDES TO OUR NORTH AND WEST. PRECIPITATION POTENTIAL WILL DIMINISH LATER WEDNESDAY NIGHT AS THIS FEATURE LIFTS NORTHEAST AND A DRY SLOT BUILDS INTO THE AREA AHEAD OF THE NEXT SYSTEM WHICH LOOKS TO COMPLICATE MATTERS FROM LATE THANKSGIVING DAY THROUGH FRIDAY. TURKEY DAY SHOULD START OUT DRY AND RELATIVELY MILD WITH TEMPS IN 45-50 RANGE FOR MORNING ACTIVITIES. THE MAIN FORECAST CONCERN WILL BE FOR THE PERIOD THURSDAY NIGHT THROUGH FRIDAY NIGHT. MODELS HAVE BEEN ADVERTISING A COMPLICATED SCENARIO FOR SEVERAL DAYS NOW...BUT THE 12Z RUNS HAVE NOW COME INTO PRETTY GOOD CONSENSUS. THE MAIN CHANGE FROM YESTERDAY IS THE LACK OF PHASING OF THE NORTHERN AND SOUTHERN STREAMS...THEREBY NEGATING THE POTENTIAL OF A BOMB TYPE STORM OVER NEW ENG OR EASTERN NY. RATHER...WE WILL BE DEALING WITH A STEEPENING UPPER TROF JUST TO OUR WEST THURSDAY AFTERNOON...CLOSING OFF INTO AN UPPER LOW OVER LK ERIE OR NORTHERN OHIO (NAM FURTHEST NORTH, GFS FURTHEST SOUTH) BY 06Z FRI. THIS FEATURE SPAWNS A SFC LOW OVER CNTRL PA WHICH WILL LIFT UP INTO SE NY FRI AFTERNOON AS UPPER LOW PUSHES EAST ACROSS NRN PA. THE LOW EVENTUALLY DEEPENS BUT NOT UNTIL IT GETS OFF THE NEW ENG COAST FRI NT. ASSUMING THIS SCENARIO PLAYS OUT...WESTERN AND CNTRL NY WILL GET OFF FAIRLY EASY AS BEST DYNAMICS WILL BE JUST SOUTH OF THE UPPER LOW AND WE WILL JUST NORTH OF THIS FEATURE. THERE WILL BE AN INITIAL SHOT OF RAIN....PERHAPS 0.25 INCH OR SO...PUSHING INTO WESTERN AREAS THURS AFTERNOON AND REACHING CNTRL NY THURS EVE. COLDER AIR WILL ADVECT IN FROM THE SOUTHWEST AS THE UPPER LOW PASSES EAST LATER THURS NT...WITH 850 MB DROPPING TO -5C OR SO ALONG NY-PA BORDER OF WESTERN SRN TIER. THUS SHOULD BE COLD ENOUGH TO CHANGE RAIN TO SNOW OVER HIGHER ELEVS...BUT MOST OF MOISTURE WILL BE STRIPPED AWAY BY 12Z FRI. CANT RULE OUT EVEN SOME WET FLAKES AS FAR NORTH AS BUF AREA BUT ANY ACCUMS HERE UNLIKELY. FRIDAY WILL BE A RAW CHILLY DAY WITH SOME RAIN/WET SNOW IN THE AIR...BUT QPF LOOKS QUITE LIGHT...UNDER 0.1 INCH. BOTH 12Z ECMWF AND GFS NOW KEEP BULK OF PRECIP E OF GENESEE VALLEY BY MIDDAY SO WEST WILL BE GENERALLY DRY IN AFTERNOON. PCPN COULD BE IN THE FORM OF WET SNOW IN AM ACROSS SOUTHERN AREAS...BUT MILDER AIR AT 850 MB WILL BE WRAPPING AROUND THE SYSTEM FROM THE EAST WITH AREAS CLOSER TO LK ONTARIO RISING FROM -4C TO -1C DURING THE DAY...SO ANYTHING WOULD BE LIQUID AT LOWER ELEVS AND E OF LK ONTARIO. MODELS PULL SYSTEM EAST A BIT FASTER THAN IN PREVIOUS RUNS... ESPECIALLY GFS WHICH BUILDS A SFC RIDGE ACROSS AREA ON SATURDAY. ECMWF A BIT SLOWER. WILL SPEED UP CLEARING BY ABOUT 6 HOURS... KEEPING UPSLOPE PCPN SE OF LAKES FRI NT BUT LITTLE OR NONE ELSEWHERE. WE DO NOT GET ESPECIALLY COLD AFTER THIS SYSTEM EVEN WITH A BRISK NW WIND FRI NT...JUST NOT ENOUGH COLD AIR TO TAP...WITH 850 MB TEMPS BOTTOMING OUT AROUND -6C...PROBABLY TOO MILD FOR ANY REAL ACCUMULATING SNOW...EVEN AT HIGHER ELEVS...WITH LOW ELEVS MAINLY LIQUID. SUMMING UP...SNOW POTENTIAL FOR THIS SYSTEM WOULD BE IN THE 1-3 INCH RANGE ACROSS SRN TIER...MAINLY HIGHER ELEVS...THURS NT/FRI AM...AND PERHAPS ANOTHER INCH OR TWO IN UPSLOPE AREAS SE OF LK ERIE AND SIMILAR AMTS ON TUG HILL FRI NT/SAT AM. LITTLE OR NOTHING ELSEWHERE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS NOTED ABOVE...MODELS CLEARING SYSTEM OUT QUICKLY BY SATURDAY... WITH GFS SHOWING A SFC RIDGE OVER AREA SATURDAY WHILE ECMWF A BIT SLOWER AND HOLDING IT OFF UNTIL SAT NT. IN ANY CASE...WILL MAINTAIN CHC POPS SE OF THE LAKES...AND CONTINUE INTO SAT EVE SE OF LK ONTARIO. P-TYPE DEPENDENT ON ELEVATIONS BUT DO NOT EXPECT ANY ACCUMS. MAINLY DRY ELSEWHERE SAT BUT CHILLY WITH MAXES IN L40S AS 850MB TROF (-5C) SWINGS THROUGH. SUNDAY LOOKS PLEASANT AS RIDGING BUILDS IN AT ALL LEVELS. 850 MB TEMPS SOAR TO +5C WHICH WOULD SUPPORT NR 50 WITH ANY SUN...ALWAYS A QUESTION THIS TIME OF YEAR...BUT A DECENT DAY NONETHELESS. NEXT SYSTEM DEEPENS OVER CENTRAL STATES MONDAY AND SLOWLY MOVES EAST...WILL INCR CHC OF SHOWERS HERE MON AFTERNOON AS THIS FEATURE APPROACHES AND CONTINUE THEM THROUGH TUESDAY. SHOULD BE QUITE MILD MON AND COLDER TUES. CONFIDENCE LOW IN DETAILS AS MODELS CONTINUE TO BUCKLE TROFS AND CLOSE THEM OFF BUT NONE HAVE BEEN ABLE TO YANK ON ANY ARCTIC AIR AND IT DOESNT LOOK LIKE ANY WILL...AT LEAST THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... BUF/IAG/ROC...FEEL FAIRLY CONFIDENT THAT DRIZZLE WILL BECOME LESS OF AN ISSUE THIS EVENING...WITH LOW CIGS/VSBY ASSOCIATED WITH THIS LOW MOISTURE DIMINISHING THROUGH THE EVENING HOURS. BASED ON BOTH NAM/GFS BUFKIT DATA...FEEL CIGS WILL SCATTER OUT ROUGHLY 06Z...THOUGH THIS IS DIFFICULT TO TIME. THIS WILL ALLOW TEMPS TO DROP NEAR THE SURFACE...WITH SOUTHERLY WINDS PICKING UP TOWARDS DAY BREAK. AT THIS POINT...CAN SEE THIS RESULTING IN PERIODIC CIGS BELOW THE INVERSION (AROUND 1000 FT)...LIGHT FOG...OR NO RESTRICTION AT ALL. HEDGE TAFS ON THE OPTIMISTIC SIDE...THOUGH HAVE VERY LOW CONFIDENCE BETWEEN 06Z - 12Z FOR THESE SITES...WITH VARIABLE CONDITIONS BETWEEN IFR AND VFR EXPECTED. ROUGHLY AFTER 12Z...EXPECT A VFR CIG TO SWEEP IN...WITH INCREASING CONFIDENCE IN VFR CIGS. BAND OF -SHRA SPREADS IN BETWEEN 18Z AND 21Z. HEDGE MORE OPTIMISTIC THAN MOS...BASED ON CLIMO WHICH SUGGESTS LOW CIGS ARE NOT CLIMATOLOGICAL LY FAVORED IN A SOUTHERLY FLOW AT THESE SITES. JHW...IR SATELLITE STARTING TO SUPPORT NAM BUFKIT...WITH BREAKS IN CIGS EXPECTED TO DEVELOP LATE THIS EVENING. THIS WILL LIKELY NOT LAST VERY LONG...WITH RADIATIONAL COOLING QUICKLY CAUSING EITHER LOW CIGS OR FOG. TAF HITS LOW CIGS HARDEST...BUT MAY SEE A PERIOD OF 1/2SM FG TONIGHT...EVEN THOUGH CIGS ARE EXPECTED TO BE THE MAIN ISSUE SINCE WINDS WILL LIKELY LIMIT FOG DEVELOPMENT. CIGS SHOULD BE SLOW TO RISE WEDNESDAY...WITH TIMING PROBLEMATIC...EVEN THOUGH SLOW LIFTING TREND SEEMS SOLID. ART...VFR CONDITIONS LIKELY THROUGH MUCH OF THE NIGHT...WITH LOWERING OF CIGS (AND POSSIBLY FOG) AFTER MIDNIGHT. BEYOND...LARGELY MVFR CONDITIONS THROUGH WEDNESDAY WITH -SHRA LATE. OUTLOOK... THURSDAY...VFR DETERIORATING TO MVFR/IFR WITH INCREASING CHANCES OF RAIN. FRIDAY...MVFR/IFR WITH RAIN LIKELY...MIXING WITH SNOW ACROSS THE SOUTHERN TIER. SATURDAY...MVFR WITH A CHANCE OF RAIN AND SNOW. && .MARINE... NO MARINE FLAGS WILL BE NEEDED FOR THE NEXT COUPLE OF DAYS. LIGHT TO GENTLE EAST TO SOUTHEAST BREEZES ON THE LOWER LAKES TONIGHT WILL RESULT IN LIMITED WAVE ACTION. SOUTH TO SOUTHWEST WINDS WILL INCREASE AHEAD OF AN APPROACH LOW PUSHING INTO THE GREAT LAKES IN THE WEDNESDAY THROUGH THURSDAY TIME FRAME...WITH CONDITIONS PROBABLY REMAINING BELOW SMALL CRAFT LEVELS...ALTHOUGH WAVE HEIGHTS APPROACHING 4 FEET ARE POSSIBLE ON LAKE ERIE WEDNESDAY NIGHT AND EARLY THURSDAY. THE NEXT THREAT FOR MARINE FLAGS WILL LIKELY BE ON FRIDAY AS A DEEPENING LOW PASSES UP TO OUR EAST. SMALL CRAFT ADVISORIES WILL BE LIKELY DUE TO BRISK NORTHWESTERLIES FRIDAY AFTERNOON AND SATURDAY. && .CLIMATE... STILL NO MEASURABLE SNOW SO FAR THIS SEASON OVER MOST OF WESTERN NY. WE ARE ALREADY OVER TWO WEEKS LATE (NORMAL DATES ARE NOV 7 BUF AND NOV 8 ROC). WE WILL AT LEAST GET TO FRIDAY (27TH) AND IF SO...WILL BE LATEST IN 61 YRS (1948) AT BUF...AND LATEST IN 46 YRS (1963) AT ROC. THE ALL TIME RECORD LATEST DATES FOR FIRST MEASURABLE SNOW ARE DEC 3 1899 AT BUF AND DEC 10 1948 AT ROC. WE WILL NOT LIKELY REACH THOSE DATES AS WX PATTERN LOOKS COLDER WITH SOME SNOW THREAT BEGINNING LATER FRIDAY. IN ADDITION, ITS BEEN A LONG TIME SINCE EITHER BUFFALO OR ROCHESTER LAST SAW MEASURABLE SNOW. THROUGH TODAY, BUFFALO HAS GONE 230 DAYS WITHOUT MEASURABLE SNOW, OR SINCE APRIL 7, 2009. THIS IS THE 6TH LONGEST STRETCH IN 125 YEARS OF RECORDS. THE RECORD IS 277 DAYS SET BACK IN 1946. ROCHESTER IS ALSO AT 230 DAYS WITHOUT MEASURABLE SNOW, OR THE 6TH LONGEST STRETCH THERE. THE RECORD IS 260 DAYS SET BACK IN 1952. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...SFM NEAR TERM...APFFEL/WCH SHORT TERM...SFM LONG TERM...SFM AVIATION...APFFEL MARINE...SFM/WCH CLIMATE...