062 FXUS61 KBUF 191034 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 634 AM EDT TUE MAR 19 2013 .SYNOPSIS... AN OCCLUDED FRONT WILL CROSS THE REGION TODAY WITH A LIGHT WINTRY MIX CHANGING TO ALL SNOW ACROSS THE REGION. AS COLDER AIR DEEPENS TONIGHT LAKE EFFECT SNOW WILL COMMENCE...EAST OF BOTH LAKE ERIE AND LAKE ONTARIO. BELOW NORMAL TEMPERATURES...LAKE EFFECT SNOW AND SNOW SHOWERS WILL CONTINUE THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... EARLY THIS MORNING AN OCCLUDED FRONT IS FOUND ACROSS WESTERN NEW YORK WITH LIGHT PRECIPITATION ALONG THE LEADING EDGE. FARTHER EASTWARD SNOW...AND IN SPOTS RAIN IS FOUND ACROSS THE EASTERN LAKE ONTARIO REGION. WATER VAPOR IMAGERY DISPLAYS AN UPPER LEVEL SHORTWAVE CROSSING THE CENTRAL GREAT LAKES. WE HAVE DROPPED THE WINTER WEATHER ADVISORY FOR SOUTHERN ERIE...WYOMING...CHAUTAUQUA AND CATTARAUGUS COUNTIES THIS MORNING WITH THE PASSAGE OF THE OCCLUDED FRONT AND COLDER AIR ALOFT RUSHING IN. ALONG AND AHEAD OF THE OCCLUDED FRONT THERE REMAINS A CHANCE FOR FREEZING RAIN...AND SNOW FROM THE SOUTHERN GENESEE VALLEY AND ACROSS THE FINGER LAKES REGION THROUGH THE MID MORNING. DRIER AIR BEHIND THE FRONT WILL CONTINUE TO PUSH ACROSS THE REGION TODAY. THIS WILL DIMINISH THE RADAR RETURNS THIS MORNING...THOUGH WILL MAINTAIN A LOW CHANCE POP WITH THE ADVANCEMENT OF THE UPPER LEVEL SHORTWAVE. THIS UPPER LEVEL SHORTWAVE MAY ENHANCE SNOW SHOWERS THIS AFTERNOON TOWARDS THE EAST WHERE SLIGHTLY DEEPER MOISTURE WILL BE FOUND. AS COLD AIR CONTINUES TO DEEPEN EXPECT THE PRECIPITATION TODAY TO CHANGE OVER TO ALL SNOW BY THE MIDDAY HOURS. TEMPERATURES WILL REMAIN STEADY TODAY...AND THEN SLIGHTLY FALLING THROUGH THE AFTERNOON WITH COLD AIR ADVECTION ALOFT. THIS COLD AIR ADVECTION WILL TRANSPORT GUSTIER WINDS DOWN TO THE SURFACE TODAY AND TONIGHT. WIND GUSTS 20 TO 30 MPH WILL BE COMMON TODAY AND TONIGHT...WITH GUSTS UP TO 40 MPH OR SO NEAR LAKE ERIE AND INLAND ACROSS THE NORTHERN NIAGARA FRONTIER...AND ACROSS NORTHERN JEFFERSON AND THE SAINT LAWRENCE VALLEY. TONIGHT LAKE EFFECT SNOW WILL INCREASE IN COVERAGE OFF BOTH LAKE ERIE AND LAKE ONTARIO. OFF LAKE ERIE...TEMPERATURES AT 850 HPA DROP TO -13 TO -14C...JUST COLD ENOUGH FOR LAKE INSTABILITY. LAKE INDUCED EQUILIBRIUM LEVELS RISE TOWARDS 8K FEET BY THIS EVENING. WINDS MAY INITIALLY START WITH A 240 FLOW AND BRING LAKE EFFECT SNOW AS FAR NORTH AS BUFFALO AND BATAVIA THIS EVENING BEFORE SLIGHT VEERING TO THE WINDS DROP A BAND OF LAKE EFFECT SNOW SOUTHWARD TOWARDS SKI COUNTRY AND THE SOUTHERN TIER. WILL HAVE A LAKE SNOW ADVISORY FOR SOUTHERN ERIE...WYOMING...CHAUTAUQUA AND CATTARAUGUS COUNTIES WHERE 4 TO 8 INCHES OF SNOW COULD ACCUMULATE LATE THIS AFTERNOON THROUGH THE OVERNIGHT. OFF LAKE ONTARIO...A WESTERLY FETCH OVER THE LENGTH OF LAKE ONTARIO WILL DRIVE A BAND OF LAKE EFFECT SNOW INLAND ACROSS THE TUG HILL REGION. WITH 850 HPA TEMPERATURES A DEGREE COLDER...AND THE LAKE A DEGREE OR TWO WARMER...COMBINED WITH LAKE INDUCED EQUILIBRIUM LEVELS JUST OVER 10K FEET A SLIGHTLY HEALTHIER BAND OF LAKE SNOWS ARE ANTICIPATED. WILL HAVE A LAKE EFFECT SNOW WARNING FOR THE EASTERN LAKE ONTARIO REGION BEGINNING TONIGHT. OUTSIDE THESE LAKE EFFECT SNOW BANDS WILL CONTINUE WITH A CHANCE FOR OVERNIGHT SNOW SHOWERS AS THE REGION WILL BE UNDER THE UPPER LEVEL TROUGH. WINDS WILL CONTINUE TO BE GUSTY TONIGHT AND WILL INCLUDE AREAS OF BLOWING SNOW WITH THE LAKE EFFECT SNOW BANDS. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... THE CALENDAR MIGHT SAY SPRING STARTS WEDNESDAY...BUT THE OVERALL PATTERN SHOWING LITTLE SIGNS OF IT. IN FACT...CONFIDENCE IS GROWING IN AN IMPRESSIVE LATE SEASON LAKE SNOW FOR PORTIONS OF WESTERN AND CENTRAL NEW YORK. BROAD LOW LEVEL COLD ADVECTION WILL BE MAINTAINED THROUGH THE PERIOD...AS A SERIES OF SHORTWAVES ROTATE THROUGH THE EASTERN GREAT LAKES REGION ON THE WESTERN PERIPHERY OF THE BROAD NORTHEAST CONUS/SOUTHEAST CANADIAN NEGATIVE UPPER HEIGHT ANOMALY. LAKE EFFECT PARAMETERS LOOKING FAVORABLE WITHIN A PERSISTENT WEST NORTHWEST FLOW REGIME. OVER-LAKE INSTABILITY QUITE IMPRESSIVE...ESPECIALLY FOR LAKE ONTARIO WITH 850 MB/LAKE DELTA TS PUSHING INTO THE MID TO UPPER TEENS. FORECAST PROFILES ALSO QUITE IMPRESSIVE IN SHOWING DEEP MOISTURE AND OMEGA THROUGH THE DENDRITIC GROWTH ZONE WITH A NEARLY NON-EXISTENT INVERSION. THE CIPS ANALOG GUIDANCE SUPPORTING SOME SIGNIFICANT SNOWFALL TOTALS IN EXCESS OF A FOOT ACROSS THE TUG HILL THROUGH THURSDAY...WITH LESSER AMOUNTS IN THE 4 TO 8 INCH RANGE SOUTHEAST OF LAKE ERIE. AT THIS POINT...THESE AMOUNTS FOR THE MOST PART LOOK REASONABLE...ESPECIALLY FOR THE HIGHER ELEVATIONS. MY MAIN CONCERN IS HOW THE USUAL DIURNAL DISRUPTION THIS TIME OF YEAR WILL CUT DOWN ON SNOW ACCUMULATIONS DURING THE DAYLIGHT HOURS OF WEDNESDAY AND THURSDAY. EXPECT THE GREATEST ACCUMULATIONS DURING WEDNESDAY NIGHT AND EARLY THURSDAY MORNING. && .LONG TERM /FRIDAY THROUGH MONDAY/... A WEAK SHORT WAVE ROTATING WITHIN THE UPPER LEVEL TROUGH PARKED OVER SOUTHEAST CANADA AND THE LOWER GREAT LAKES IS FORECAST TO MOVE THROUGH THE AREA FRIDAY AND FRIDAY NIGHT. THIS SYSTEM WILL BRING A PERIOD OF SNOW SHOWERS AND LAKE ENHANCED SNOWS TO THE FAVORED AREAS SOUTHEAST OF LAKE ERIE AND ONTARIO. AFTER THIS SYSTEM MOVES THROUGH MID-LEVEL DRYING AND 850H TEMPERATURES START WARMING FROM -13C TO -9C BY LATE SATURDAY. SO ANY LINGERING LAKE EFFECT SNOWS DOWN WIND OF THE LAKES WILL LIKELY COME TO A SLOW END WITH MAINLY JUST SOME LEFT OVER FLURRIES. TEMPERATURES DURING THIS PERIOD WILL START OUT BELOW NORMAL BUT WILL GRADUALLY CLIMB TO NEAR NORMAL BY MONDAY AS THE TROUGH OVER THE REGION SLOWLY WEAKENS AND MODIFIES. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AT 06Z IFR TO VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION. TOWARDS THE SOUTHERN TIER LOW CLOUDS CONTINUE TO LINGER ACROSS THE KJHW TERMINAL...AND AS DRIER AIR PUSHES INTO THE REGION COMBINED WITH DAYTIME MIXING THESE CIGS SHOULD LIFT TO MVFR. THERE IS ALSO IFR FLIGHT CONDITIONS TOWARDS THE EAST WHERE A MIX OF SNOW...AND SOME RAIN CONTINUES ACROSS THE NORTHERN FINGER LAKES REGION AND THE EASTERN LAKE ONTARIO REGION. THIS SHIELD OF PRECIPITATION WILL LINGER ACROSS THE EASTERN LAKE ONTARIO REGION THROUGH THE MORNING HOURS WITH CONTINUED IFR FLIGHT CONDITIONS. FARTHER WEST SCATTERED RAIN AND SNOW SHOWERS CONTINUE ACROSS WNY WITH MVFR TO VFR FLIGHT CONDITIONS. AN OCCLUDED FRONT WILL CONTINUE TO CROSS THE REGION THIS MORNING. AS IT DOES WINDS WILL VEER TO MORE OF A SOUTHWESTERLY FLOW. COLDER AIR BUILDING IN ALOFT AND DAYTIME MIXING WILL ALLOW FOR WIND GUSTS OF 25 TO 35 KNOTS TO REACH THE SURFACE ACROSS THE REGION. WITH A CONTINUED UPPER LEVEL TROUGH OVER THE REGION A FEW SCATTERED EARLY MORNING RAIN/SNOW SHOWERS WILL BECOME ALL SNOW THROUGH THE MORNING. WILL CONTINUE WITH VCSH AS A DRY SLOT WILL PUSH ACROSS THE REGION KEEPING PRECIPITATION TO THE MINIMAL SIDE. A TEMPO GROUP WILL BE ADDED TO THE KART TAF SITE FOR THIS AFTERNOON AS A POSSIBLE SQUALL OF SNOW IS POSSIBLE ALONG THE LEADING EDGE OF THE UPPER LEVEL SHORTWAVE AND UPPER LEVEL THERMAL BOUNDARY. CONFIDENCE FOR THIS TO OCCUR AT THIS TIME IS LOW. LATER THIS AFTERNOON AND EVENING AS COLDER AIR DEEPENS ACROSS THE REGION LAKE EFFECT SNOW WILL INCREASE. OFF LAKE ERIE THIS BAND MAY EXTEND NORTHWARD AND CLIP THE BUFFALO AIRPORT FOR A FEW HOURS THIS EARLY EVENING BEFORE SETTLING SOUTHWARD. OFF LAKE ONTARIO A WESTERLY FLOW WILL ORIENT THE BAND OF SNOW WATERTOWN SOUTHWARD THROUGH THE OVERNIGHT HOURS. WITHIN THIS BAND OF SNOW IFR AND LOWER FLIGHT CONDITIONS ARE EXPECTED. OUTLOOK... WEDNESDAY AND THURSDAY...MVFR/IFR IN SNOW SHOWERS AND LAKE EFFECT SNOW. FRIDAY...MVFR WITH LIGHT SNOW SHOWERS. SATURDAY...MAINLY VFR. && .MARINE... WILL CONTINUE WITH SMALL CRAFT ADVISORIES THROUGH THIS TIME PERIOD AS COLD AIR DEEPENS BEHIND AN OCCLUDED FRONT THAT IS PASSING ACROSS LAKE ONTARIO THIS MORNING. A SMALL CRAFT WILL CONTINUE FOR THE UPPER NIAGARA RIVER THROUGH WEDNESDAY MORNING AS SOUTHWEST WINDS WILL AT TIMES REACH 20 KNOTS SUSTAINED OVER THE RIVER. SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED THROUGH WEDNESDAY NIGHT TO COVER THE GUSTY WINDS AND WAVES GREATER THAN 4 FOOT. GUSTS MAY OCCASIONALLY APPROACH GALES ON THE LAKES BUT NOT REMAIN SUSTAINED FOR ANY LONGER PERIOD OF TIME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER STORM WARNING UNTIL 8 PM EDT THIS EVENING FOR NYZ006>008. LAKE EFFECT SNOW WARNING FROM 8 PM THIS EVENING TO 6 PM EDT THURSDAY FOR NYZ006>008. WINTER WEATHER ADVISORY UNTIL 11 AM EDT THIS MORNING FOR NYZ004-005-013-014-021. LAKE EFFECT SNOW ADVISORY FROM 5 PM THIS AFTERNOON TO 6 AM EDT THURSDAY FOR NYZ012-019-020-085. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR LOZ042>045. && $$ SYNOPSIS...THOMAS NEAR TERM...THOMAS SHORT TERM...TMA LONG TERM...AR AVIATION...THOMAS MARINE...THOMAS