370 FXUS61 KBUF 202018 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 318 PM EST Sun Nov 20 2022 .SYNOPSIS... Heavy lake effect snow will impact southeast of Lake Ontario, centered on Oswego county through this evening. Moderate to locally heavy lake effect snow bands will impact the Southern Tier into this evening. Additionally gusty winds this afternoon and again on Monday will create blowing and drifting of the recently fallen snow. && .NEAR TERM /THROUGH MONDAY/... Two plumes of lake effect snow continue to the east of the Lakes. Outside these plumes of snow, breezy conditions with west gusts up to 45 mph have created blowing snow with reduced visibilities, as well as drifting of snow. Interesting that wind gusts briefly reached 45-48 mph over portions of the Niagara Frontier/Genesee valley where it is sunny and mixing has been maximized. These stronger winds are beginning to diminish recently though. Cold persists with single digit wind chills into tonight all areas. Off Lake Erie... A westerly flow has focused the snow showers across the Southern Tier. Mainly moderate intensity, though have seen a few heavier snow showers as well. Shallower lake equilibrium level and drier air and connection lessening off upstream lakes will continue to diminish the snow into tonight. Remnants of this snow will come back north overnight across Buffalo in a much weakened state. Total snow accumulations through tonight will be a few inches of fluffy snow in the Southern Tier to an inch or two otherwise across far WNY, including the Buffalo Metro. Off Lake Ontario... Much more well developed, but still wavering band of lake effect continues to impact the corridor from Oswego into southern Lewis county early this afternoon helped by wnw flow bringing in upstream connections to central Great Lakes. Radar trends and consensus of high-res guidance, including HRRR and Canadian High res do point to a more notable shift southward of this band into at least early evening, so this will put the band into far northeast Wayne, far northern Cayuga and much of Oswego county. Snowfall rates of 2-3" per hour likely along with some lightning. No changes to the going headlines. This shift will have to happen for snow to come into Wayne county, but again, it looks to be occurring at present. Oswego county should see storm totals since late last night of 2-3 feet in some areas. Later tonight, similar to the Lake Erie band, expect the band to weaken and shift back to the north across northern Oswego, much of Jefferson and adjacent Lewis county. A lot of the weakening will occur due to loss in upstream connections, but there is a hint that the plume of moisture from Lake Erie band will try to briefly connect with the eastern Lake Ontario band. If that were to happen r rates could push toward 1" per hour into Watertown late tonight with up to a few inches of accumulation tonight. By Monday morning the weakening bands of snow...with their last gasps of light snow showers at Buffalo/Niagara Falls and Watertown will lift into Canada by late morning, losing any upstream lake connection, and finally ending. This lake effect snow event starting Wednesday evening for some locations has been a very long duration event lasting over 100 hours. Later Monday a cold front will advance across southern Canada and our region. Residual lake moisture collecting ahead of the front may bring a few rain or snow showers back into our region. Of bigger concern a tightening pressure gradient ahead of the upstream trough and departing surface high will bring wind gusts about 5 to 10 mph stronger than Sunday. While this could continue the blowing snow, the extra day of compaction along with surface temperatures rising above freezing in many locations will reduce the blowing snow threat. Regardless, winds possibly gusting towards advisory levels will occur northeast of the Lakes and possibly even toward ROC on the Niagara Frontier. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... There may be some lingering lake effect snow showers Monday night as a shortwave passes by to our north. It does look marginally cold enough for snow, with -6C at 850mb ahead of the shortwave. Any accumulations will be minor especially considering recent snowfall. Expect less than an inch east of Lake Erie, and 1-3 inches on the Tug Hill. On Tuesday night despite a more zonal flow developing, weak southwest low-level flow sets up and it again is just marginally cold for a lake response (-6c at H85) though inversions are only 3-5kft. Just a small chance we could see some snow showers northeast of Lake Ontario. This would then shift toward southeast Lake Ontario on into Wednesday. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... A shortwave trough overhead Wednesday morning will track east of the area by Wednesday afternoon. Westerly flow and marginally cold enough temperatures for lake effect may result in some rain and snow showers east of Lake Ontario through the afternoon. Elsewhere, dry conditions expected. Highs will reach the low 40s. The synoptic pattern will become amplified the latter half of the week as trough deepens across the Mid-West region and an upper level ridge builds across the Northeast. Surface low pressure will be deepening east of the trough however timing and location is yet to be determined. Warm air and moisture advection is likely across the eastern Great Lakes region beginning Thursday night and rain and snow showers are likely during this time period. It is fairly certain that moisture and cold air will wrap around this system through the weekend with lake effect snow showers possible. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... Bands of lake effect snow with visibilities dropping to VLIFR to LIFR continue to the east of the Lakes. Off Lake Erie the band has settled south of the Buffalo and Rochester airports and will impact KJHW this afternoon with IFR/LIFR visibility. Otherwise, even outside of this band, gusty winds to 35 knots will result in blowing snow at times at BUF and IAG. Off Lake Ontario into this evening the primary snow band will persist southeast of Lake Ontario between ROC and ART. Mainly VFR at ART, though there will be occasional BLSN and reduced visibility. Tonight the lake effect snow will begin to drift northward again, in a much weaker state. A few snow showers, with brief reduction to IFR is possible for KBUF and KART by the end of tonight. Outlook... Monday....MVFR/VFR with a chance of rain and snow showers. Very Windy with gusts 40 knots or greater possible. Tuesday through Thursday...Mainly VFR. Friday...Chance of rain and snow showers. MVFR/IFR possible. && .MARINE... Gale force winds this afternoon will diminish some tonight, then back to southwest on Monday while increasing to 35-40 knots on both Lakes. In coordination with NWS Cleveland and Canada we have ran with one gale warning through Monday, even though there will likely be a 12+ hr window of sub-gale force winds tonight on the Lakes. Small craft advisories will be in place for the Niagara River as well as the Saint Lawrence River. Winds are expected to be stronger Monday on the Saint Lawrence River where a southwesterly flow down the river valley could reach 25 knots sustained. High pressure will push towards the region Monday night and Tuesday, relaxing the pressure gradient and allowing for winds and waves to decrease. && .TIDES/COASTAL FLOODING... Strong winds late today will cause levels on Lake Erie to rise some. Water levels will likely approach 6 feet above low water datum at the Buffalo NOS station. Levels higher than this can cause minor splash over in a few spots along the Lake Erie shoreline. && .CLIMATE... Buffalo airport received 21.5 inches of snowfall Saturday, breaking the daily record and bringing our monthly total 36.9 inches. Saturday, November 19th was the 2nd snowiest calendar day for the month of November in Buffalo's history...trailing only the November 20, 2000 date which had 24.9 inches of snow. This snow also makes November 2022 the 2nd snowiest on record (the snowiest is back in 2000 when there was 45.6 inches of snow). && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Weather Advisory until 7 PM EST this evening for NYZ001- 002-007-010>012-085. Winter Weather Advisory until 1 AM EST Monday for NYZ004. Lake Effect Snow Warning until 1 AM EST Monday for NYZ005. Lake Effect Snow Warning until 4 AM EST Monday for NYZ006-008. Lake Effect Snow Warning until 10 PM EST this evening for NYZ019-020. Winter Weather Advisory until 10 PM EST this evening for NYZ021. MARINE...Small Craft Advisory until 7 PM EST Monday for LEZ020. Gale Warning until 10 PM EST Monday for LEZ040-041. Small Craft Advisory until 7 PM EST Monday for LOZ030. Gale Warning until 1 AM EST Tuesday for LOZ042>045-062>065. Small Craft Advisory until 10 PM EST Monday for SLZ022-024. && $$ SYNOPSIS...JLA/Thomas NEAR TERM...JLA/Thomas SHORT TERM...JLA LONG TERM...HSK AVIATION...JLA MARINE...JLA/Thomas TIDES/COASTAL FLOODING...Apffel/TMA CLIMATE...Thomas