Issued by NWS Buffalo, NY
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KBUF 222339 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 639 PM EST SUN NOV 22 2009 .SYNOPSIS... HIGH PRESSURE EXTENDING FROM NEW BRUNSWICK TO THE OHIO VALLEY WILL KEEP DRY AIR OVER THE REGION THROUGH MONDAY. MOISTURE FROM A LOW MOVING UP THE MID ATLANTIC COAST WILL BRING A THREAT OF LIGHT RAIN TO AREAS FROM THE GENESEE VALLEY EASTWARD MONDAY NIGHT THROUGH TUESDAY MORNING. WEAK HIGH PRESSURE WILL FOLLOW LATER TUESDAY AND TUESDAY NIGHT. THE NEXT CHANCE OF SHOWERS WILL ARRIVE WEDNESDAY AS LOW PRESSURE MOVES INTO THE WESTERN AND CENTRAL LAKES. TEMPERATURES WILL BE ABOVE AVERAGE THROUGH THE MIDDLE OF THE WEEK BEFORE A COOLING TREND BY LATE WEEK. && .NEAR TERM /THROUGH MONDAY/... 300 PM UPDATE...LAST OF THE STRATUS OVER MONROE-WAYNE CONTINUES TO ERODE RAPIDLY...WITH MOST OF THE REGION ENJOYING A FINE NOVEMBER AFTERNOON UNDER PLENTY OF SUNSHINE AND TEMPS IN 50S. WE SHOULD CLEAR OUT COMPLETELY BY SUNSET. ISSUE TONIGHT WILL BE POTENTIAL FOR FOG. WILL INCLUDE IT IN TYPICAL SRN TIER VALLEYS BUT HOLD OFF ELSEWHERE AS LOWER LAYERS HAVE PROBABLY MIXED OUT ENOUGH...BUT THIS NOT A CERTAINTY SO EVE SHIFT WILL NEED TO MONITOR FOR POSSIBLE EXTENSION. MONDAY LOOKS TO BE ANOTHER FINE DAY THIS ATYPICAL NOVEMBER WITH PLENTY OF SUNSHINE AFTER ANY EARLY MORNING FOG BURNS OFF...AT LEAST FOR AWHILE. THE SUN WILL FADE BEHIND THICKENING CLOUDS FROM SOUTH TO NORTH DURING THE AFTERNOON AS A COMPLEX LOW PRESSURE SYSTEM OVER THE SOUTHEAST STATES LIFTS GRADUALLY NORTH...BUT THEN GETS SHEARED NORTHEAST AND EAST AND TAKES MOST IF NOT ALL OF ITS MOISTURE TO OUR SOUTH AND EAST (SEE SHORT TERM-MONDAY NIGHT). WILL INCLUDE SLGT CHC POPS CATT/ALLEG COS ONLY TWD SUNSET MONDAY. AS FOR TEMPS...WILL FOLLOW MILDER MAV/GFS ONES AS SEE NO REASON WHY WE WONT GET SIMILAR NUMBERS TO TODAY`S (L-M 50S) WITH SIMILAR 850/925MB TEMPS AND ENOUGH SUNSHINE. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...-- Changed Discussion --MONDAY NIGHT AND TUESDAY, AN EASTERLY FLOW OF ATLANTIC MOISTURE BETWEEN HIGH PRESSURE OFF THE CANADIAN MARITIMES AND LOW PRESSURE ALONG THE MID ATLANTIC COAST WILL SPREAD WESTWARD INTO MUCH OF THE REGION WHILE A MID LVL SHORTWAVE MOVES NE ACROSS THE LOWER LAKES. THE COASTAL LOW IS EXPECTED TO MOVE TO CAPE COD BY TUESDAY AFTERNOON. THE QUESTION IS HOW FAR WEST TO BRING THE THREAT OF LIGHT RAIN. AT THIS TIME BOTH THE NAM AND GFS KEEP THE ACTIVITY TO THE EAST OF BUF, MNLY ACROSS AREAS FROM THE GENESEE VALLEY EASTWARD MONDAY NIGHT, AND AREAS EAST OF THE GENESEE VALLEY TUESDAY MORNING. THE THREAT SHLD END BY LATER TUESDAY ACROSS THE REST OF THE EASTERN PTNS OF THE CWA. WEAK HIGH PRESSURE SHLD FOLLOW TUESDAY AFTERNOON AND NIGHT. MODEL PROFILES SHOW PLENY OF LOW LVL MOISTURE HANGING OVER THE REGION UNDER THE WEAK HIGH SO DON`T EXPECT MUCH IN THE WAY OF ANY CLEARING. ON WEDNESDAY, THE HIGH MOVES EAST OF THE AREA AND A SOUTHERLY FLOW OF INCREASINGLY MOIST AIR AHEAD OF LOW PRESSURE MOVING INTO THE WESTERN LAKES BEGINS TO MOVE INTO THE REGION. THE NAM IS SLOWER THAN THE GFS/ECMWF IN BRINGING IN THE MOISTURE WEDNESDAY. HAVE GONE TOWARD THE GFS/ECMWF BRINGING IN THREAT OF SHWRS TO AREAS FROM THE FINGER LKS WEST IN THE MRNG AND THEN REACHING AREAS EAST OF LK ONTARIO DURG THE COURSE OF THE AFTERNOON. TEMPS SHLD CONTINUE WITH ABV NORMAL HIGHS BOTH TUE AND WED. GENLY UPPER 40S TO LOWER 50S TUE AND LOW TO MID 50S WED. LOWS MON NGT SHLD RANGE FROM 35 TO 40 MONDAY NIGHT AND TUESDAY NIGHT.-- End Changed Discussion --&& .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...-- Changed Discussion --THE NOW WELL ADVERTISED PATTERN CHANGE STILL APPEARS ON TRACK TO ARRIVE LATE WEEK. THE CURRENT PATTERN ACROSS THE NOAM SECTOR FEATURES A BROAD TROUGH OVER THE WEST WITH A RIDGE DOWNSTREAM OVER MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE CONUS. THE GEFS ENSEMBLE MEAN CONTINUES TO FORECAST THE NAO INDEX TO BECOME WEAKLY NEGATIVE BY THE END OF THE MONTH...WITH THE PNA INDEX TRENDING POSITIVE. IN THE MEAN...THIS SHOULD YIELD A COLDER PATTERN FOR THE GREAT LAKES AND NORTHEAST FOR THE LAST WEEK OF NOVEMBER INTO EARLY DECEMBER WITH A TROUGH FAVORED OVER THE EASTERN CONUS IN SUCH A PATTERN. THE IN DICIES ARE NOT FORECAST TO BE PARTICULARLY STRONG HOWEVER...SO NO DRAMATIC PATTERN CHANGE IS EXPECTED...RATHER A TREND TOWARDS COOLER AND MORE SEASONABLE TEMPERATURES. LOOKING AT THE DETAILS...THE LOW CONTINUES OVER THE CENTRAL LKS WED NGT INTO THANKSGIVING DAY BUT 850 TEMPS SHLD STAY WARM ENOUGH FOR THE PRECIP DURG THIS PERIOD TO BE IN THE FORM OF RAIN SHOWERS. COLDER AIR BEGINS TO FILTER IN BEHIND THE LOW THANKSGIVING NIGHT WITH A CHANCE OF RAIN/SNOW SHOWERS. FRIDAY AND SATURDAY A DEEP LONGWAVE TROUGH WILL CARVE OUT IN THE LOWER LAKES AND OHIO VALLEY. THE LATEST 12Z GFS AND ECMWF BOTH DEVELOP A MAJOR COASTAL LOW...WITH THE GFS JUST A TAD FARTHER WEST, INLAND OVER NEW ENGLAND. BOTH OF THESE SOLUTIONS WOULD SUGGEST THE POTENTIAL FOR SIGNIFICANT QPF FOR CENTRAL AND EASTERN NY. PRECIP TYPE WILL BE A TOUGH CALL ON FRIDAY AS TEMPS MAY STILL BE WARM ENOUGH FOR A RAIN/SNOW MIX DURG FRIDAY WITH PRECIP CHANGING TO SNOW SHOWERS FRIDAY NIGHT. SATURDAY, WITH NW FLOW BEHIND THE LOW EXPECT CHC RAIN/SNOW SHWRS WITH HIGHS GENLY UPPER 30S TO ARND 40. WILL CONTINUE CHC SNOW SHWRS SAT NGT SE OF LKS ERIE AND ONTARIO AS COLD NW FLOW CONTINUES WITH ONLY SLGT CHC POPS OUTSIDE OF THESE AREAS. ON SUNDAY HIGH PRESSURE WILL SPREAD INTO THE REGION WITH DRIER AIR.-- End Changed Discussion --&& .AVIATION /00Z MONDAY THROUGH FRIDAY/...-- Changed Discussion --AS OF 2330Z...TWO LINGERING PATCHES OF STRATUS...ONE NEAR KROC AND ONE ACROSS PORTIONS OF THE NORTH COUNTRY...CONTINUE TO ERODE IN PLACE WITH CONTINUED DRY AIR ENTRAINMENT INTO THE CLOUD LAYER. THESE SHOULD CONTINUE TO BREAK APART OVER THE COURSE OF THE NEXT FEW HOURS AND DISSIPATE BY 02Z...LEAVING BEHIND VFR CONDITIONS FOR THE BALANCE OF THE EVENING. DURING THE REMAINDER OF THE NIGHT...RIDGING IS EXPECTED TO REMAIN INTACT OVER THE AREA WITH GENERALLY CLEAR SKIES CONTINUING. WITH ONLY A WEAK GRADIENT IN PLACE OVERNIGHT AND SFC DEWPOINTS STILL RUNNING A BIT HIGH...WOULD NOT BE SURPRISED TO SEE SOME PATCHY MVFR FOG FORM JUST ABOUT ANYWHERE OVERNIGHT...AND HAVE THEREFORE ADDED THIS TO THE FORECAST FOR LATER TONIGHT. ANY PATCHY FOG THAT DEVELOPS OVERNIGHT SHOULD THEN QUICKLY DISSIPATE WITH SUNRISE AND THE RETURN OF DIURNAL HEATING ON MONDAY...LEAVING BEHIND VFR CONDITIONS FOR THE BALANCE OF THE DAY WITH ONLY AN INCREASE IN CIRRUS EXPECTED DURING THE AFTERNOON. OUTLOOK... MONDAY NIGHT AND TUESDAY...MAINLY VFR. WEDNESDAY AND THURSDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS. FRIDAY...MVFR WITH A CHANCE OF RAIN/SNOW SHOWERS.-- End Changed Discussion --&& .MARINE... WINDS AND WAVES ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVSRY RANGE THROUGH TUESDAY. THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER NEW BRUNSWICK AND LOW PRESSURE ALONG THE MID ATLANTIC COAST WILL RESULT IN AN INCREASE IN EASTERLY WINDS ON THE WESTERN PORTION OF LAKE ONTARIO MONDAY AFTERNOON AND EVENING. IT WILL PRODUCE CHOPPY CONDITIONS ON THE WESTERN HALF OF LAKE ONTARIO...BUT CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA. && .CLIMATE... STILL NO MEASURABLE SNOW SO FAR THIS SEASON OVER MOST OF WESTERN NY. WE ARE ALREADY 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 MEAS 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. STAY TUNED. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...JJP NEAR TERM...SFM SHORT TERM...JJP LONG TERM...JJP AVIATION...JJR/SFM MARINE...JJP CLIMATE...SFM
