Marine Weather and Tide Forecast for Clayton, NY

NEAR TERM /THROUGH WEDNESDAY/
The core of a deep upper level trough over central NY this morning will continue to shift east towards the Gulf of Maine through this evening as a sfc low deepens and tracks north across eastern Quebec.
In its wake, a progressive sfc ridge will build over the forecast area by this afternoon. Ongoing NW flow lake effect snow showers will continue through the remainder of the morning hours, then gradually taper off as dry air subsidence brings down inversion heights and depletes DGZ moisture. The focus for heaviest snow until then will be southeast of Lake Erie across the Chautauqua Ridge as an upstream connection to Lake Huron wraps northward, and along the south-southeastern shoreline of Lake Ontario with upstream connections to Georgian Bay impacting the Niagara Frontier at times.
While some lake effect/upslope snow showers may continue into the afternoon, the overhead airmass will already be modifying behind the trough axis enough for all areas at the lower elevations to rise several degrees above freezing, not quite enough for a mix with rain though it should help melt the snow on the ground and area roadways.

Behind the surface ridge, a negatively tilted shortwave and broad surface trough will descend southeast across the Great Lakes this evening and through tonight. This will cause the prevailing flow to back to the southwest, which in combination with the added fetch, moisture and forcing, allow newly formed bands of lake effect precip off both lakes to rapidly whip northward. Off Lake Erie, the band will pass over the Buffalo Metro and into Niagara Country before daybreak Wednesday, then slowly trek back southward over the course of the day. The band should be due east of the lake by the early evening. The band off Ontario will lag behind by several hours, though it will move northward from the the Tug Hill region after midnight before moving across the Watertown Metro. The band is expected to linger north of the metro through the morning before settling back towards the Tug Hill by the evening.

The main forecast challenge tonight into Wednesday morning continues to be p-type and how efficient dendrite-growth processes will be. As previously alluded to, the airmass will be modifying this period, with a slow warming of temps aloft through tonight and a more rapid warming Wednesday. This will inevitably cause a mix with rain to occur Wednesday morning, first across WNY with a complete changeover in most areas by the afternoon, though the timing of this changeover remains a bit uncertain. In addition, BUFKIT soundings indicate this warmer airmass should lead to an elevated DGZ with a capping inversion below it, despite near total saturation through the column at times. This should help preclude the development of larger, more efficiently accumulating dendrites. This said, given the timing of the bands around the Wed morning commute, their proximity to the metro areas, and ongoing NW flow lake effect this morning, have opted to include N. Erie, Lewis, and Jefferson to the latest rounds of advisories, and extend Niagara/Orleans until Wednesday morning.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/
Longwave trough axis lying across the Northeast Wednesday night will allow a shortwave trough to slide southeast through the base of the longwave trough, which will pull the trough axis east into the northern Atlantic Thursday and Thursday night. Meanwhile, a ridge will lie across the upper Great Lakes and northern Midwest. Under the exiting trough's regime, cool northwest winds will continue to filter across the region Wednesday night through Thursday night.
While temperatures aloft at 850mb will continue to support lake effect showers, temperatures will be warmer (average around -5C)
than the current airmass and therefore support mainly rain showers and a few higher terrain and night time snow showers southeast of both lakes Erie and Ontario Wednesday night through Thursday night.
This being said, areas southeast and east of both Lakes Erie and Ontario Wednesday night through Thursday night can expect between a half inch to three quarters of an inch of rain, with locally higher amounts possible. Additionally, for the areas cold enough to support night-time (mainly across the higher terrain) snow accumulations of a few tenths of an inch will be possible.

Showers will begin to taper off Thursday night as the ridge begins to push east into the far western portions of the region.

LONG TERM /FRIDAY THROUGH MONDAY/
Amplified upper level and mid-level trough-ridge-trough pattern late this week and into the start of next week will support mainly active weather to persist with a brief lull in activity this weekend.

Heading into Friday, exiting mid-level trough in the northern Atlantic, will allow ridging and associated surface high pressure to push east across the central and lower Great Lakes. Warming temperatures aloft (warming towards 0C at 850mb) will help end lake effect rain showers and night time higher elevation snow will peter off Friday and Friday night.

Surface high pressure shifting overhead Saturday will support a period of dry weather. However this period of dry weather will be short term as the next mid-level trough heads towards the region late Sunday night and into the start of next week. Warmer thermal profiles continue to support mainly rain showers Sunday afternoon through Monday.

AVIATION /12Z TUESDAY THROUGH SATURDAY/
Variable flight conditions as an area of upper level low pressure will track east of the region through tonight. Synoptic moisture and cold northwesterly flow in its wake will allow for widespread lake effect snow showers to continue downwind of the lakes this morning, with a particular focus southeast of Lake Erie and south-southeast of Lake Ontario. Inside the main lake effect areas expect mainly MVFR cigs and MVFR/IFR vsbys, with a gradual improvement to VFR/MVFR elsewhere. The snow coverage and intensity will gradually taper off through the day today with vsbys becoming mainly VFR as drier air moves overhead.

Tonight, more focused bands of lake effect snow will rapidly come northward off both lakes, with impacts likely at KBUF, KIAG, and KART. Snow intensity should be modest at best though localized MVFR/IFR will certainly be possible. A changeover to rain may occur late in the band off Lake Erie, though confidence in timing is low.
VFR/MVFR with scattered snow showers will prevail elsewhere.

Outlook...

Wednesday.. MVFR/IFR with rain and snow, especially east and northeast of the lakes. Windy.

Thursday...Areas of MVFR with rain and snow showers likely, especially southeast and east of the lakes.

Friday.. MVFR/VFR with a chance for rain and snow showers.

Saturday...Mainly VFR.

MARINE
A surface low is along the New England shoreline will continue to deepen as it tracks northward towards Quebec today. This will maintain a prolonged period of strong winds over the eastern Great Lakes with high end small craft conditions on the Lakes. As winds turn southwesterly this evening, a short period of low-end Gales is expected on Lake Erie into early Wednesday morning.

Waves are expected to remain 4-feet and greater through Thursday evening on the eastern Great Lakes, and not until Friday when surface high pressure approaches the Lower Lakes will winds and waves fall below small craft conditions.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Winter Weather Advisory until 10 AM EST Wednesday for NYZ001- 002-010.
Winter Weather Advisory until 1 PM EST this afternoon for NYZ003>006-020-085.
Winter Weather Advisory until 1 PM EST Wednesday for NYZ007- 008.
Lake Effect Snow Warning until 1 PM EST this afternoon for NYZ019.
MARINE...Small Craft Advisory until 7 PM EST this evening for LEZ040- 041.
Gale Warning from 7 PM this evening to 4 AM EST Wednesday for LEZ040-041.
Small Craft Advisory until 7 PM EST this evening for LOZ042>045.