Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 291129 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 729 AM EDT SUN MAR 29 2015 .SYNOPSIS... HIGH PRESSURE WILL SLOWLY DRIFT AWAY FROM THE AREA TODAY AND STILL SUPPORT PLENTY OF SUNSHINE. LOW PRESSURE WILL PASS JUST NORTH OF THE GREAT LAKES TONIGHT AND MONDAY BRINGING GUSTY WINDS AND A LIGHT MIX OF WET SNOW AND RAIN WITH SOME MINOR SLUSHY ACCUMULATIONS ACROSS HIGHER TERRAIN. ANOTHER SYSTEM MAY BRING WET SNOW AND RAIN TO WESTERN NY TUESDAY BEFORE HIGH PRESSURE BRINGS A RETURN TO DRY WEATHER FOR WEDNESDAY. TEMPERATURES WILL REMAIN BELOW NORMAL EARLY IN THE WEEK BEFORE A STRONG PUSH OF WARMING ARRIVES ON THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... A SURFACE RIDGE PARKED FROM THE CENTRAL APPALACHIANS TO THE LOWER LAKES WILL CONTINUE TO PROVIDE CLEAR SKIES THROUGH THIS MORNING FOR THE ENTIRE REGION. UNSEASONABLE COLD THIS MORNING WILL SLOWLY MODERATE UNDER SUNSHINE...BUT TEMPERATURES WILL STILL REMAIN BELOW NORMAL WITH HIGHS IN THE UPPER 30S ACROSS LOWER ELEVATIONS AND MID 30S ACROSS HIGHER TERRAIN AND EAST OF LAKE ONTARIO. SOME OF THE TYPICALLY WARMER LOCATIONS IN THE GENESEE VALLEY MAY JUST ECLIPSE THE 40F MARK. THE FULL SUNSHINE WILL LAST MOST IF NOT ALL OF TODAY WITH JUST SOME HIGH/THIN CIRRUS BUILDING DURING THE AFTERNOON. THE WEATHER BECOMES MORE ACTIVE TONIGHT AS A POTENT MID LEVEL TROUGH DIGS FROM NORTHWEST ONTARIO PROVINCE INTO WESTERN QUEBEC BY MONDAY MORNING WITH AN ASSOCIATED MODERATELY STRONG SURFACE LOW TAKING A SIMILAR TRACK. A TRAILING OCCLUDED FRONT WILL CROSS OUR REGION OVERNIGHT AND FOCUS A PERIOD OF DEEPER MOISTURE AND STRONG LOW LEVEL CONVERGENCE SUPPORTED BY A 50-60 KNOT LOW LEVEL JET. AN INITIAL LEAD MID LEVEL SHORTWAVE WILL COMBINE WITH THE LOW LEVEL JET SUPPORTED LOW LEVEL CONVERGENCE FIELD TO BRING A BAND OF PRECIP FROM WEST TO EAST ACROSS THE AREA TONIGHT...MOVING INTO WESTERN NY AROUND MID EVENING THEN REACHING THE EASTERN LAKE ONTARIO REGION SHORTLY AFTER MIDNIGHT. BEHIND THE INITIAL AREA OF PRECIP THERE MAY BE A BRIEF LULL...BUT ADDITIONAL STRONG DPVA AHEAD OF THE MAIN MID LEVEL TROUGH AND TERRAIN INDUCED CONVERGENCE AND UPSLOPE EAST OF BOTH LAKES ERIE AND ONTARIO WILL CONTINUE TO SUPPORT SOME LIGHT PRECIP IN MOST AREAS OVERNIGHT. PTYPE WILL BE SOMEWHAT COMPLEX AS THE BOUNDARY LAYER BECOMES FAIRLY MILD OVERNIGHT. THE FIRST BAND OF PRECIP SHOULD BE MAINLY SNOW... ALTHOUGH A FEW RAINDROPS MAY MIX IN ON THE LEADING EDGE. EVAPORATIVE COOLING SHOULD COOL THE COLUMN ENOUGH TO FORCE ANY INITIAL RAIN/SNOW TO CHANGE TO ALL SNOW IN MOST AREAS. BEHIND THE INITIAL BATCH OF PRECIP LOW LEVEL WARM ADVECTION WILL ALLOW RAIN TO MIX IN AGAIN LATE ACROSS LOWER ELEVATIONS AS SURFACE TEMPERATURES CREEP UPWARD THROUGH THE 30S LATE TONIGHT. AS FAR AS ACCUMULATIONS GO...LIMITED QPF AND MARGINAL TEMPERATURES WILL ONLY SUPPORT A SLUSHY COATING IN MOST AREAS. HIGHER TERRAIN MAY SEE AN INCH OR SO OF ACCUMULATION. IT WILL BECOME WINDY OVERNIGHT AS THE PRESSURE GRADIENT RAPIDLY TIGHTENS AND THE LOW LEVEL JET PASSES OVERHEAD. EVAPORATE COOLING FROM THE FIRST WAVE OF PRECIP MAY HELP TO BRING SOME STRONGER MOMENTUM DOWN TO THE SURFACE. EXPECT GUSTS OF 25-35 MPH TO BE COMMON LATER TONIGHT...WITH GUSTS OF 40-45 MPH NORTHEAST OF LAKES ERIE AND ONTARIO WITH TYPICAL FUNNELING DOWN THE LAKES. A FEW GUSTS TO NEAR ADVISORY LEVELS CANNOT BE RULED OUT...BUT GIVEN THE LACK OF COLD ADVECTION AND RELATIVELY POOR LOW LEVEL LAPSE RATES EXPECT MOST OF THE STRONGER MOMENTUM TO REMAIN ALOFT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... TROUGHING OVERHEAD ON MONDAY WILL MAKE FOR A SHOWERY AND COOLER DAY. STEEP LAPSE RATES UNDER THE UPPER-LEVEL TROUGH WILL SUPPORT SOME SCATTERED...LOW-TOPPED CONVECTIVE RAIN AND SNOW SHOWERS THROUGH THE DAY MONDAY. AN EMBEDDED VORTICITY MAX IS PROGGED TO SWING THROUGH THE BASE OF THE TROUGH / AND ACROSS WESTERN NY / BY MID-DAY MONDAY. THIS SHOULD HELP TO REINVIGORATE SHOWER ACTIVITY AND MAKE IT BRIEFLY MORE WIDESPREAD. PRECIPITATION TYPE REMAINS SOMEWHAT OF A QUESTION GIVEN THE RELATIVELY WARM SURFACE TEMPERATURES. HOWEVER WITH STEEP LAPSE RATES ABOVE THE SURFACE...THE MAJORITY OF THE COLUMN WILL BE BELOW FREEZING. GIVEN ANY ENHANCED PRECIPITATION RATES IN THE CONVECTIVE SHOWERS /AND DYNAMICAL COOLING/ EXPECT SNOW WILL LIKELY BE THE DOMINATE P-TYPE...BUT WILL NOT RULE A LITTLE RAIN MIX AT TIMES. NEVERTHELESS...SNOW ACCUMULATIONS ARE MAINLY OUT OF THE QUESTION THROUGH THE DAY MONDAY...EXCEPT FOR A BRIEF LIGHT DUSTING UNDER A HEAVIER SNOW SHOWER. WINDS WILL BE NOTICEABLY STRONGER ON MONDAY...AS THE SURFACE LOW TRACKS JUST NORTH OF THE FORECAST AREA TIGHTENING THE PRESSURE GRADIENT ACROSS THE AREA. A CORE OF 40 KT WINDS AT 925 - 850 MB WILL TRACK ACROSS THE FORECAST AREA...HOWEVER WITH ASCENT ASSOCIATED WITH THE UPPER-LEVEL LOW AND WEAK CAA...IT WILL BE DIFFICULT TO MIX THESE STRONGER WINDS TO THE SURFACE FOR MUCH OF THE DAY. SOME WIND GUSTS UP TO 40 MPH COULD BE MIXED DOWN THROUGH THE CONVECTIVE SHOWERS...AND POTENTIALLY LATER IN THE DAY BEHIND THE VORT MAX ROTATING ACROSS THE AREA. OTHERWISE WINDS OF 20 TO 30 MPH WILL BE COMMON ON MONDAY. BY MONDAY NIGHT...THE TROUGH AXIS PIVOTS OFF THE NEW ENGLAND COAST AND DRIER AIR WILL FILTER IN FROM THE WEST. GIVEN THE LACK OF SIGNIFICANT COLD AIR CONNECTION BEHIND THE SURFACE LOW...LOW TEMPERATURES MONDAY NIGHT INTO TUESDAY MORNING WILL MAINLY BE IN THE UPPER 20S. BY TUESDAY...MODELS ARE IN GOOD AGREEMENT ABOUT A CLIPPER SHORTWAVE DIVING FROM THE UPPER GREAT LAKES INTO PENNSYLVANIA. DISCREPANCIES BETWEEN THE MODELS ARISE IN THE NORTH-SOUTH POSITION OF THE WAVE AS IT PASSES BY THE FORECAST AREA. THE NAM REMAINS ON THE MORE NORTHERLY EDGE OF THE MODEL SPREAD...WHILE THE ECMWF REMAINS ON THE MORE SOUTHERLY EDGE OF THAT SPREAD. A MORE SOUTHERLY TRACK MEANS LESS IMPACT TO THE FORECAST AREA...SUPPRESSING THE BULK OF THE PRECIP INTO PA...AND ALSO COOLER TEMPERATURES ON TUESDAY AS THE BAROCLINIC ZONE IS SET UP FARTHER SOUTH. HAVE TAKEN A CONSENSUS APPROACH TO THIS PORTION OF THE FORECAST...WITH THE OFFICIAL FORECAST USING A BLEND OF THE GFS/NAM/EC/GEM/SREF SOLUTIONS. KEPT LOW END LIKELY POPS LIMITED TO THE SOUTHERN TIER...WHICH IS THE ONLY PORTION OF THE FORECAST AREA THAT IS IMPACTED BY BOTH ENDS OF THE MODEL SPECTRUM. OTHERWISE...POPS TAPER OFF TO CHANCE TOWARD LAKE ONTARIO...AND NEAR ZERO IN THE NORTH COUNTRY WHICH SHOULD REMAIN OUT OF THE IMPACT OF THIS SYSTEM. PRECIPITATION TYPE IS AGAIN TRICKY WITH THIS SYSTEM...AS THE COLD AIR TAP IS LIMITED. FORECAST SOUNDINGS AGAIN INDICATE A SHALLOW LAYER OF ABOVE FREEZING TEMPERATURES AT THE SURFACE...AND THUS P-TYPE MAY BECOME DEPENDED ON RATE / DYNAMICAL COOLING PROCESSES. THUS HAVE CONTINUED TO MAINTAIN A RAIN / SNOW MIX IN THE FORECAST. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... WEDNESDAY INTO THURSDAY...MODELS ARE IN GOOD AGREEMENT FOR SOME LOW-AMPLITUDE RIDGING WORKING ACROSS THE AREA. THIS WILL BRING TEMPERATURES WARMING INTO MID 40S ON WEDNESDAY / WHICH LOOKS LIKE THE ONLY CERTAIN DRY DAY IN THE EXTENDED FORECAST. AS THE RIDGE AXIS WORK ACROSS THE AREA ON THURSDAY AND SOUTHWESTERLY FLOW BECOMES ESTABLISHED ALOFT...TEMPERATURES COULD PUSH WELL INTO 50S / IF NOT THE LOW 60S IN PORTIONS OF THE AREA. THE TRADE OFF FOR THESE WARMER TEMPERATURES WILL BE INCREASING CLOUD COVER AND CHANCES FOR PRECIPITATION TO CLOSE OUT THE WEEK. MODELS ARE IN GOOD AGREEMENT ABOUT THE WEATHER PATTERN BECOMING MORE UNSETTLED BY LATE THURSDAY THROUGH SATURDAY AS OVERALL TROUGHING LOOKS LOOKS TO BE A SURE BET. HOWEVER MODELS CONTINUE TO STRUGGLE WITH THE EXACT DETAILS AND TIMING OF ANY WEATHER SYSTEMS THAT DEVELOP OUT OF THIS PATTERN. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... VFR WILL PREVAIL THROUGH EARLY THIS EVENING ACROSS THE ENTIRE REGION. HIGH PRESSURE OVER THE OHIO VALLEY AND LOWER LAKES WILL SLOWLY DRIFT TO THE EAST COAST TODAY...AND CONTINUE TO PROVIDE CLEAR SKIES. THIN HIGH CIRRUS LEVEL CLOUDINESS WILL BEGIN TO INCREASE LATER TODAY AHEAD OF THE NEXT SYSTEM. THIS EVENING A SHARP MID LEVEL TROUGH AND OCCLUDED FRONT AT THE SURFACE WILL APPROACH THE AREA. A NARROW ZONE OF FOCUSED ASCENT ALONG THIS FEATURE WILL PRODUCE A PERIOD OF LIGHT SNOW...ENTERING WESTERN NY AROUND 02Z THEN OVERSPREADING THE REST OF THE AREA OVERNIGHT. THE SNOW MAY BRIEFLY MIX WITH RAIN AT THE ONSET...BUT EVAPORATIVE COOLING SHOULD QUICKLY CHANGE ANY MIX BACK TO ALL SNOW. THIS WILL PRODUCE AREAS OF IFR VSBY...WITH CIGS INITIALLY STAYING MAINLY VFR. LATE TONIGHT THE BOUNDARY LAYER MAY AGAIN BECOME MILD ENOUGH TO ALLOW SOME RAIN TO MIX IN ACROSS THE LAKE PLAINS. BY THIS TIME THE STEADIER PRECIP WILL HAVE MOVED EAST AND WEAKENED...LEAVING MORE INTERMITTENT RAIN AND WET SNOW SHOWERS WITH MAINLY MVFR VSBY EAST OF THE LAKES. WINDS WILL INCREASE THIS EVENING AS THE PRESSURE GRADIENT TIGHTENS...WITH GUSTS OF OVER 20 KNOTS IN MOST AREAS AND OVER 30 KNOTS NORTHEAST OF LAKE ERIE DUE TO FUNNELING DOWN THE LAKE. OUTLOOK... MONDAY THROUGH TUESDAY...AREAS OF MVFR AND SPOTTY IFR IN RAIN/SNOW SHOWERS. WEDNESDAY...VFR. THURSDAY...VFR/MVFR. A CHANCE OF RAIN SHOWERS. && .MARINE... HIGH PRESSURE WILL DRIFT AWAY FROM THE REGION AND TOWARDS THE EASTERN SEABOARD TODAY. SSW WINDS WILL INCREASE TO 15-20 KNOTS IN THE WAKE OF THE DEPARTING HIGH...BUT THAT WIND DIRECTION WILL KEEP THE GREATER WAVE ACTION IN THE CANADIAN WATERS OF LAKE ONTARIO. A MODERATELY STRONG AREA OF LOW PRESSURE WILL PASS BY JUST NORTH OF THE GREAT LAKES TONIGHT AND MONDAY. THIS WILL BRING A RAPID INCREASE IN SOUTHWEST WINDS TONIGHT...BECOMING WEST ON MONDAY. THE STRONGER WINDS WILL BRING AT LEAST HIGH END SMALL CRAFT ADVISORY CONDITIONS TO THE OPEN PORTIONS OF LAKE ONTARIO...WITH SUSTAINED WINDS REACHING AROUND 30 KNOTS ON BOTH LAKES. THE GFS REMAINS STRONGER THAN THE NAM OR CANADIAN GEM GUIDANCE...AND IF IT WERE TO VERIFY LOW END GALES MAY BE POSSIBLE ON LAKE ONTARIO FOR A FEW HOURS ON MONDAY. FOR NOW WE HAVE PEAKED THE WINDS AT 30 KNOTS WITH A HIGH END SMALL CRAFT. WINDS WILL QUICKLY DIMINISH MONDAY NIGHT AS THE SYSTEM MOVES INTO THE CANADIAN MARITIMES. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 AM EDT TUESDAY FOR LOZ042-043. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...HITCHCOCK SHORT TERM...CHURCH LONG TERM...CHURCH AVIATION...HITCHCOCK MARINE...HITCHCOCK

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