Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 150352 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1052 PM EST Sat Dec 14 2019 .SYNOPSIS... Deepening low pressure is heading off to Quebec and widespread snow is fading fast across all but the eastern Lake Ontario region. Attn into Sunday will turn to lingering lake effect snow showers east of the lakes, heaviest over the Tug Hill region. There will be a brief break Sunday afternoon through most of Monday before the next area of low pressure moves just south the region with snow and a wintry mix Monday night through Tuesday. && .NEAR TERM /THROUGH SUNDAY/... ...Wet snow fading fast over western NY but moderate snow continues east of Lake Ontario... Have cancelled all the winter weather advisories over western NY. Advisories continue east of Lake Ontario. Winter storm warnings in place will continue through 7 AM for additional lake effect and some blowing snow that kicks in overnight east of Lake Erie. As sub 985mb low heads north into Quebec, wet system snow is fading fast across much of western NY toward Finger Lakes. Still seeing decent snow east of Lake Ontario, though some reports indicate still just raining along immediate Lake Ontario shore with strong onshore winds, and that snow should continue next few hours before diminishing. As the snow ends, may see some drizzle or freezing drizzle depending on sfc temps. Eventually overnight, becomes cold enough for lake response off Lake Erie and also Lake Ontario. Lake effect into Sunday morning should fall at moderate clip from southern Erie into western Southern Tier. Kept the warning going here as another 3 inches, maybe 4 inches, could fall on top of what has already occurred. Snow will diminish on Sunday for these areas as drier air and rising mid- level heights work into the region from the west. Think the better lake effect into Sunday will occur east of Lake Ontario toward Tug Hill. Even after forcing and synoptic snow from the low departs overnight, soundings over eastern Lake Ontario region indicate temps of -10c to -14c in the lake effect convective layer. Capping inversions are fairly low though, only 4-6kft, so that likely will limit intensity of lake effect once the lake enhanced setup that is going at this time departs later tonight. Thus far, snow totals in western NY have reached 6-8 inches (with bullseye in far southern Erie county) and up to 3-5 inches (higher terrain south of Rochester toward Bristol Hills area in Ontario county). Amounts in the Niagara Falls/Buffalo areas closer to Lake Erie were held down to 1-2 inches, due in large part to very low SLRs (only 4:1 with our ob at 7 PM as we had 1.2 inches of snow with 0.29 inches of liquid). For updated reports that are rolling in see PNSBUF and LSRBUF. Back to Lake Ontario, snow is just getting going with recent report of change to snow on the Tug Hill at Redfield and NY mesonet starting to show some accumulation occurring on the Tug Hill. This event will be over a longer duration given that some of the snow will be from lake enhanced upslope flow Sunday morning following the main synoptic event tonight. Expect an additional 2-4 inches across the lower elevations (less near Lake Ontario), and 4-8 inches across the Tug Hill Plateau. The higher accumulations will be limited to a small portion of the Tug Hill region where elevation is the highest. We will continue to monitor this area for a possible upgrade, but given the snow will fall over a longer period of time and the higher amounts will be isolated to the top of the Tug Hill, an advisory still seems reasonable. Finally, it is beginning to turn breezy as the surface low continues to deepen across eastern Quebec. Expect gusts of 30-40 mph across much of the region, highest on the lake plains close to Lake Ontario. The snow will be quite wet and sticky given the marginal temperatures, so blowing snow will not be much of an issue at first. Some blowing snow will develop later tonight through Sunday in open areas once temperatures turn colder and the snowfall becomes drier. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... Lake effect snow showers will be diminishing east of Lake Erie and Lake Ontario as high pressure slides from west to east across the region Sunday night. Low pressure will be developing across the lower Mississippi Valley as a shortwave trough moves into the Central Plains Sunday night. Cyclogenesis will occur as it moves into the Central Appalachians and interacts with the right entrance region of an upper level jet Monday. The low-level jet with this system looks to stay south of the New York State border and the northern fringe of the precipitation shield will approach the area. There is a chance of light snow Monday afternoon across the southern half of western NY. Dry conditions are expected in vicinity of Lake Ontario including the North Country. Mostly dry conditions will change Monday night when the shortwave trough moves into the Ohio Valley and further interacts with the surface low over the central Appalachians. Increased lift and moisture will move across western and north central NY. Cold air advection will increase across the region and snow will spread across the region Monday night through Tuesday. While there will be some lake enhancement when the synoptic moisture diminishes, widespread snow will end from west to east by Tuesday afternoon. A few inches of snowfall accumulation are possible across the region Monday night-Tuesday. At this time, accumulation looks to stay under headline issuance however, this will depend on the track and location of the deformation zone which will be watched in the coming days. Cold air advection will continue Tuesday night. A mid-level trough will move southeast into the Great Lakes region by Wednesday morning. This will bring moisture and further intensify cold air advection across the region. Lake effect snow showers will increase during this time. Temperatures will average slightly below normal with highs in the low to mid 30s Monday and Tuesday and lows in the low to mid 20s Sunday night through Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A closed mid level low will track from the Great Lakes to the Northeast Wednesday. Surface low pressure is expected to track across southern Ontario and Quebec during this time. This will drag a cold front through western and north central NY. Guidance has been locked on that 850mb temperatures will fall to around -20C producing extreme lake induced instability mid-week. West-northwest flow will likely lead to lake effect snow east-southeast of the Lakes Wednesday into Wednesday night. The steepening lapse rates may also increase the risk of snow squalls Wednesday afternoon outside of lake bands. While conditions look favorable for lake effect snow, this event also looks short-lived. A mid-level ridge will move into the region late Wednesday night into Thursday which will veer winds and cut off moisture. Drier weather expected late in the week while temperatures remain below normal. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Snow is diminishing steadily across western NY, though moderate snow remains east of Lake Ontario. Expect lake effect snow to become main issue later tonight into Sunday downstream of the lakes. IFR to lower MVFR cigs will continue the rest of the night. VSBY will mainly be MVFR except at JHW and ART where occasional IFR VSBY may still occur in heavier snow. CIGS will eventually become more MVFR as Sunday wears on while VSBY will become VFR. Expect VFR conditions for all the terminals by Sunday evening. Outlook... Monday...VFR deteriorating to IFR Monday night with snow developing. A wintry mix possible near the PA state line. Tuesday...IFR in snow in the morning, improving to mainly VFR. Wednesday and Thursday...A chance of IFR in lake effect snow east of the lakes, with VFR elsewhere. && .MARINE... A deepening low lifting across Quebec will continue to deepen through Sunday morning. Westerly winds will continue to increase on Lake Ontario with gale force winds for the rest of the night. Westerly gales will continue through Sunday before starting to diminish Sunday night. A gale warning continues for most of Lake Ontario. Winds will not be quite as strong on Lake Erie farther removed from the strong low. Sustained winds will likely peak around 30 knots on Lake Erie. Winds will diminish Sunday night as the pressure gradient relaxes across the eastern Great Lakes. && .TIDES/COASTAL FLOODING... West gales on Lake Ontario tonight through Sunday will produce significant wave action on the east half of the lake, and combine with high lake levels to increase the risk of lakeshore flooding. Wind direction is expected to be nearly due west for the duration of the strong winds, which will drive the higher risk of Lakeshore flooding to areas from about Fair Haven eastward where the shoreline is more perpendicular to a west wind. Farther west along the south shore of Lake Ontario, winds will be parallel to the shoreline. On Lake Erie, winds will remain lighter, in the 25-30 knot range. The wind direction is also due west, which is not quite aligned with the long axis of the lake and less favorable for a seiche. With this in mind, just expect a minor rise at the east end of Lake Erie. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Lakeshore Flood Warning until 10 PM EST Sunday for NYZ005>007. Winter Weather Advisory until 1 PM EST Sunday for NYZ006>008. Winter Storm Warning until 7 AM EST Sunday for NYZ012-019-020- 085. MARINE...Small Craft Advisory until 7 PM EST Sunday for LEZ020. Small Craft Advisory until 9 PM EST Sunday for LEZ040-041. Small Craft Advisory until 7 PM EST Sunday for LOZ030. Gale Warning until 7 PM EST Sunday for LOZ043>045-062>065. Small Craft Advisory until midnight EST Sunday night for LOZ042. Small Craft Advisory until 7 PM EST Sunday for SLZ022- 024. && $$ SYNOPSIS...Hitchcock/JLA NEAR TERM...Hitchcock/JLA SHORT TERM...HSK LONG TERM...HSK AVIATION...Hitchcock/JLA MARINE...Hitchcock/JLA TIDES/COASTAL FLOODING...Hitchcock/JLA

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