Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 071211 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 711 AM EST SUN FEB 7 2016 .SYNOPSIS... TODAY WILL LIKELY BE THE NICEST WEATHER DAY OF THE WEEK...AS UNIMPRESSIVE HIGH PRESSURE WILL GUARANTEE DRY WEATHER WHILE ENCOURAGING TEMPERATURES TO CLIMB WELL ABOVE NORMAL. A LARGE STORM SYSTEM DEVELOPING OVER THE UPPER GREAT LAKES WILL THEN DRIFT OVER OUR REGION DURING THE NEXT SEVERAL DAYS...AND THIS WILL LEAD TO FREQUENT AND LARGELY INCONSEQUENTIAL SNOWS. TEMPERATURES WILL GENERALLY TREND LOWER AS WE WORK OUR WAY THROUGH THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... WEAK RIDGING AND GENERAL LARGE SCALE SUBSIDENCE FOUND BETWEEN A BROAD STORM SYSTEM OVER THE UPPER MISSISSIPPI VALLEY AND A DEEP COASTAL LOW OFF THE CAROLINAS WILL GUARANTEE FAIR DRY WEATHER OVER OUR REGION TODAY...BUT THIS RELATIVELY NICE WEATHER WILL NOT LAST LONG THOUGH...SO ENJOY IT WHILE YOU CAN. A PAIR OF VIGOROUS SHORTWAVES OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES THIS MORNING WILL TRACK SOUTHEAST TODAY AND CARVE OUT A FRESH TROUGH OVER THE UPPER MISSISSIPPI VALLEY. WHILE THIS WILL KEEP A LOW AMPLITUDE RIDGE MOVING TO THE EAST ACROSS OUR REGION...IT WILL ALSO START TO BACK OUR MID LEVEL FLOW. THIS WILL SLOW THE EASTWARD ADVANCE OF MID LEVEL CLOUD COVER THAT IS FOUND BACK ACROSS LOWER MICHIGAN...SO THAT THE BULK OF TODAY SHOULD FEATURE A FAIR AMOUNT OF SUN. THESE CLOUDS WILL GRADUALLY MAKE THEIR WAY ACROSS THE FAR WESTERN COUNTIES AFTER LUNCHTIME. RE-FOCUSING ON THE EASTERN LAKE ONTARIO REGION...HIGH PRESSURE CENTERED NEAR JAMES BAY WILL PUSH A WEAKENING ARCTIC FRONTAL BOUNDARY OVER SOUTHERN ONTARIO THIS MORNING...THEN SOUTH ACROSS THE LAKE AND THE NORTH COUNTRY WHERE IT WILL STALL LATE TODAY. GIVEN THAT THERE IS STILL A FAIR AMOUNT OF MID LEVEL MOISTURE IN THAT REGION WITH MORE ADVECTING IN FROM UPSTREAM...ANY WEAK LIFT FROM THIS FRONT SHOULD HELP TO KEEP SKIES PRTLY/MSTLY CLOUDY. THIS WILL ESPECIALLY BE THE CASE NORTH OF WATERTOWN TOWARDS THE THOUSAND ISLANDS. WHILE THE FRONT WILL LIKELY PLAY A PART IN THE SKY COVER FOR THAT REGION...THE COLDER AIR IN ITS WAKE IS NOT EXPECTED TO MAKE IT MUCH FURTHER SOUTH THAN MASSENA. SPEAKING OF TEMPERATURES...WEAK WARM ADVECTION TAKING PLACE BETWEEN THE TWO STORM SYSTEMS WILL MODIFY OUR H85 TEMPS TO BETWEEN -2 AND -4C. THIS IN COMBINATION WITH AT LEAST PARTIAL SUNSHINE WILL SUPPORT AFTERNOON MAX TEMPS IN THE MID 40S ACROSS THE WRN COUNTIES...WITH EVEN MILDER CONDITIONS POSSIBLE IN THE GENESEE VALLEY. MEANWHILE THE MERCURY WILL TOP OUT IN THE UPPER 30S TO NEAR 40 EAST OF LK ONTARIO. TONIGHT...THE AFOREMENTIONED SHORTWAVES WILL DIG INTO THE BASE OF A RAPIDLY DEEPENING LONGWAVE TROUGH. IN FACT...A CLOSED LOW SHOULD TAKE SHAPE IN THE VCNTY OF WISCONSIN BY DAYBREAK. AT THE SFC...THE ARCTIC COLD FRONT WILL ESSENTIALLY WASH OUT OVER THE EASTERN LAKE ONTARIO REGION WHILE A BROAD SFC LOW WILL DRIFT ACROSS THE U.P OF MICHIGAN. THIS SYNOPTIC SET UP WILL SHARPEN THE SOUTHERLY GRADIENT OVER THE LOWER GRADIENT...FURTHER DETERRING PCPN FROM MAKING ITS WAY EASTWARD AHEAD OF A SFC OCCLUSION. WHILE THIS WILL KEEP OUR FORECAST AREA PCPN FREE THROUGH THE OVERNIGHT...CLOUDS WILL INCREASE AND THICKEN ACROSS THE FORECAST...PARTIALLY ENHANCED BY AN INCREASINGLY DIVERGENT UPPER LEVEL FLOW. TEMPERATURES ACROSS OUR REGION TONIGHT WILL AVERAGE SOME 15 DEG F ABOVE NORMAL EARLY FEBRUARY LEVELS...AS LOWS ARE ONLY EXPECTED TO BE IN THE UPPER 20S TO LOWER 30S. ITS PROBABLY WORTH NOTING THAT THE BULK OF THE TEMPERATURE DROP FOR TONIGHT WILL TAKE PLACE BEFORE MIDNIGHT...AS THE SOUTHERLY FLOW WILL HELP TO STABILIZE THE MERCURY THROUGH THE WEE HOURS OF THE MORNING. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... A MID LEVEL CLOSED LOW WILL MOVE FROM SOUTHERN WISCONSIN EARLY MONDAY MORNING TO THE OHIO VALLEY BY TUESDAY MORNING BEFORE OPENING UP INTO A BROAD MID LEVEL TROUGH DURING THE MIDDLE OF THE WEEK. AT THE SURFACE A WEAKENING LOW WILL MOVE INTO THE CENTRAL LAKES MONDAY AND THEN GIVE WAY TO WEAK SECONDARY COASTAL CYCLOGENESIS MONDAY NIGHT. THIS WILL LEAVE BEHIND A WELL DEFINED INVERTED TROUGH ACROSS THE LOWER LAKES CONNECTING THE OLD PARENT LOW WITH THE COASTAL LOW. THE INVERTED TROUGH WILL CONTINUE TO PROVIDE A DIFFUSE FOCUS FOR WEAK CONVERGENCE MONDAY NIGHT THROUGH TUESDAY NIGHT. LOOKING AT THE DETAILS...ON MONDAY THE APPROACH OF THE MID LEVEL CLOSED LOW AND ASSOCIATED DPVA AND UPPER LEVEL DIVERGENCE WILL PROVIDE AN INCREASE IN LARGE SCALE ASCENT BY MONDAY AFTERNOON ACROSS WESTERN NY...WITH THIS RELATIVELY WEAK FORCING SPREADING EAST ACROSS THE REMAINDER OF THE AREA MONDAY NIGHT. AN OCCLUDED FRONT AT THE SURFACE WILL GRADUALLY MOVE INTO WESTERN NY AND PROVIDE SOME ADDITIONAL LOW LEVEL CONVERGENCE. EXPECT RELATIVELY LIGHT PRECIP TO GRADUALLY SPREAD INTO WESTERN NY DURING THE LATE MORNING AND EARLY AFTERNOON...THEN REACH THE GENESEE VALLEY BY LATE AFTERNOON OR EARLY EVENING BEFORE REACHING CENTRAL NY AND THE NORTH COUNTRY OVERNIGHT. BOUNDARY LAYER TEMPS ARE QUITE MILD INITIALLY ON MONDAY...SO EXPECT A RAIN/WET SNOW MIX OR EVEN JUST RAIN AT THE ONSET ACROSS WESTERN NY. PRECIPITATION WILL SLOWLY TRANSITION OVER TO SNOW MONDAY NIGHT AS WEAK COLD ADVECTION SPREADS INTO THE AREA. EXPECT THE TRANSITION TO BE ELEVATION DEPENDENT...WITH THE HIGHER TERRAIN GOING TO ALL SNOW FIRST...AND THE LAKE PLAINS CHANGING TO ALL SNOW LAST. THE MILD BOUNDARY LAYER TEMPS WILL PREVENT ANY ACCUMULATION IN MOST AREAS MONDAY WITH JUST A COATING POSSIBLE ON THE HILLS OF THE WESTERN SOUTHERN TIER. MONDAY NIGHT EXPECT A COATING OF ACCUMULATION ACROSS LOWER ELEVATIONS AND AROUND AN INCH ACROSS HIGHER TERRAIN. TUESDAY AND TUESDAY NIGHT THE INVERTED TROUGH WILL REMAIN ACROSS THE AREA AS THE SECONDARY COASTAL LOW TAKES SHAPE. THIS WILL LEAVE BEHIND WEAK/DIFFUSE FORCING PRODUCING AREAS OF LIGHT SNOW. THE WEAK NATURE OF THE FORCING AND STILL MARGINAL BOUNDARY LAYER TEMPS DURING THE DAY TUESDAY WILL KEEP ANY ADDITIONAL ACCUMULATIONS AN INCH OR LESS...WITH SIMILAR LIGHT AMOUNTS TUESDAY NIGHT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... WEDNESDAY AND THURSDAY THE LOWER LAKES WILL REMAIN UNDER THE INFLUENCE OF THE BROAD MID LEVEL TROUGH. AT THE SURFACE AN INVERTED TROUGH WILL REMAIN IN PLACE ACROSS THE LOWER LAKES WHILE SEVERAL WEAK WAVES OF LOW PRESSURE DEVELOP ALONG THE EAST COAST. THE INVERTED TROUGH IS FORECAST TO SHARPEN WEDNESDAY NIGHT AND MOVE SOUTH ACROSS THE LOWER LAKES AS A KICKER SHORTWAVE ROUNDS INTO THE LONGWAVE TROUGH. THE SHARPENING OF THE INVERTED TROUGH WILL ACT TO ENHANCE LOW LEVEL CONVERGENCE LATER WEDNESDAY AND WEDNESDAY NIGHT. COLD ADVECTION WILL ALSO INCREASE THE CONTRIBUTION OF LAKE MOISTURE AND INSTABILITY AS LAKE INDUCED EQUILIBRIUM LEVELS STEADILY RISE. GIVEN THE FORECAST PATTERN EVOLUTION...WEDNESDAY NIGHT AND THURSDAY WILL LIKELY BE THE TIME FRAME OF BEST SNOW ACCUMULATIONS FROM THIS SYSTEM. IN MOST AREAS THE ACCUMULATIONS WILL STILL BE MODEST...BUT THE COMBINATION OF LAKE ENHANCEMENT AND UPSLOPE FLOW MAY LEAD TO HEAVIER ACCUMULATIONS ACROSS THE HIGHER TERRAIN OF THE CHAUTAUQUA RIDGE EAST OF LAKE ERIE. LAKE ENHANCEMENT MAY ALSO BRING BETTER ACCUMULATIONS TO AREAS ALONG THE SOUTH SHORE OF LAKE ONTARIO. LATER THURSDAY AND THURSDAY NIGHT THIS SYSTEM FINALLY PULLS INTO THE CANADIAN MARITIMES WITH SYNOPTIC SCALE SNOW ENDING FROM WEST TO EAST. LAKE EFFECT SNOW SHOWERS WILL CONTINUE SOUTHEAST OF BOTH LAKES AS 850MB TEMPS CONTINUE TO DROP TO AROUND -20C. FORECAST UNCERTAINTY INCREASES SOME FRIDAY INTO THE WEEKEND WITH THE HANDLING OF A TRUE ARCTIC AIRMASS. THE 00Z ECMWF REMAINS CONSISTENT WITH PREVIOUS RUNS IN DROPPING THE CORE OF A FRIGID AIRMASS ACROSS THE LOWER LAKES AND NEW ENGLAND THIS WEEKEND WITH 850MB TEMPS BOTTOMING OUT AROUND -30C. THESE FORECAST TEMPERATURES ALOFT ARE ON PAR WITH THE COLDEST EVER RECORDED IN THE MONTH OF FEBRUARY AT KBUF. THE 00Z GFS DIRECTS THE CORE OF THE COLD THROUGH QUEBEC AND INTO NORTHERN MAINE...WITH A COLD BUT LESS EXTREME AIRMASS MOVING INTO OUR REGION. GIVEN THE MODEL UNCERTAINTY WILL CONTINUE WITH A RELATIVELY CONSERVATIVE FORECAST WITH HIGHS IN THE LOWER TEENS ON SATURDAY WITH SINGLE NUMBERS ACROSS THE NORTH COUNTRY. IF THE COLDER ECMWF SOLUTION VERIFIES THIS WILL NEED TO BE ADJUSTED SIGNIFICANTLY DOWNWARD. THE FRIGID AIRMASS WILL PRODUCE SOME LAKE EFFECT SNOW SHOWERS SOUTHEAST OF THE LAKES...BUT AIRMASSES THIS COLD ARE ALSO VERY DRY AND THIS WILL LIMIT ACCUMULATIONS DESPITE THE STRONG INSTABILITY. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... WEAK HIGH PRESSURE WILL KEEP FAIR VFR CONDITIONS IN PLACE ACROSS ALL OF WESTERN AND NORTH CENTRAL NEW YORK TODAY...AS MID LEVEL CLOUD COVER WILL GRADUALLY INCREASE OVER THE FAR WESTERN COUNTIES DURING THE AFTERNOON. WHILE A LARGE STORM SYSTEM WILL TAKE SHAPE ACROSS THE UPPER GREAT LAKES TONIGHT...FAIR WEATHER WILL REMAIN IN PLACE OVER OUR REGION. CLOUDS WILL LOWER AND THICKEN THOUGH DURING THE COURSE OF THE NIGHT...ESPECIALLY OVER THE WESTERN COUNTIES. OUTLOOK... MONDAY...MVFR. RAIN OR SNOW LIKELY. MONDAY NIGHT THROUGH THURSDAY...MVFR/IFR IN PERIODS OF SNOW. && .MARINE... WEAK RIDGING OVER THE LOWER GREAT LAKES WILL PRODUCE GENTLE TO MODERATE BREEZES TODAY...AS WAVES WILL AVERAGE WELL BELOW SMALL CRAFT ADVISORY LEVELS. WHILE A LARGE STORM SYSTEM WILL DEVELOP OVER THE UPPER GREAT LAKES LATE TODAY AND TONIGHT...THE SFC PRESSURE GRADIENT WILL REMAIN WEAK OVER THE LOWER GREAT LAKES. THIS WILL KEEP GENTLE TO OCCASIONALLY MODERATE BREEZES IN PLACE. ON MONDAY...THE APPROACHING STORM SYSTEM WILL FRESHEN AN EAST TO SOUTHEAST FLOW OVER THE LOWER GREAT LAKES...PARTICULARLY LAKE ONTARIO. THE SOMEWHAT HIGHER WINDS ARE NOT EXPECTED TO BE A PROBLEM THOUGH...AS THE FLOW WILL KEEP THE HIGHEST WAVES IN CANADIAN WATERS. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...HITCHCOCK LONG TERM...HITCHCOCK AVIATION...RSH MARINE...RSH

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