Marine Weather and Tide Forecast for Dunkirk, NY

NEAR TERM /THROUGH TONIGHT/

FRIGID COLD WITH SIGNIFICANT LAKE EFFECT SNOWS EXPECTED

During this period the axis of deep upper level troughing will slowly make its way from the central Great Lakes to New England...
with its attendant pool of arctic air continuing to flood across our region. This will lead to dangerously cold conditions as 850 mb temps fall to as low as -25C or so...which at the surface will translate into high temperatures struggling to get much above the 5 to 15 above zero range today...with lows tonight then falling into the negative single digits in areas away from the lakeshores
Coupled with expected winds
this will result in apparent temperatures dipping into the -15 to -20 range at times...
for which Cold Weather Advisories remain in effect areawide through Wednesday morning.

The bitterly cold airmass and prevailing west to southwest flow will also continue to generate significant lake snows east/northeast of the lakes
The long fetch across the lakes
coupled with lake- induced equilibrium levels of 10-12 kft over Lake Erie and 13-14 kft over Lake Ontario along with sufficiently rich moisture and strong lake-induced instability will allow for continued intense snows of up to 3" per hour at times through today and into this evening. The lake snows will then weaken from west to east through the course of tonight as low-level ridging builds across our area and introduces drier air
lowering inversion heights/lake EQLs
and an increase in low level shear.

In terms of the movement of the lake snows...activity initially south of Buffalo and Watertown early this morning will generally lift northward across the Buffalo/Watertown areas during the course of the late morning and afternoon hours as winds back out ahead of the approaching mid/upper level trough axis and an attendant weak surface trough. The bands will then shift back southward again into the Southern Tier and Tug Hill regions again late this afternoon and this evening as the flow goes more westerly in the wake of the trough passage...with weakening of the low level flow also allowing the bands to retract back closer to the lakeshores tonight.

Digging a bit further into the details...

Off Lake Erie...lake snows extending from far northern portions of the Southern Tier to the Buffalo Southtowns early this morning will likely lift northward across the city of Buffalo/Buffalo airport and the Northtowns between later this morning and afternoon. This northward shift from the previous forecast reflects a slightly more backed southwesterly flow and more northerly band position seen in the most recent guidance...and lies between the NAM and GEM positioning...with the latter still looking to be a bit too far north (a tendency it has had with some other lake effect events so far this winter season)
At its apex
the northern edge of the band may get far enough north to temporarily spread some snow/snow showers into southern Niagara and Orleans counties...before veering winds send the lake snows back south across the Buffalo area late this afternoon/early this evening...then into the Southern Tier by the middle of the night. The lake snows will also begin weakening later on this evening as ridging introduces drier air and crashes the cap down to about 5 kft...while also retracting back toward the lakeshore as the flow across the lake weakens
By late tonight
expect just some remnant light snow showers to be leftover along the lakeshore southwest of Buffalo.

Based on what has been experienced since late yesterday...have significantly bumped up snow ratios/snow totals for the upcoming 24 hours...with another 1-2 feet appearing likely where the snows are most persistent...with the peak likely extending from the southern Erie county lakeshore across south Buffalo and the Buffalo Southtowns. Further north expect a general 6-12" across much of the rest of Buffalo and the central and eastern suburbs...with progressively lower amounts further northward. With the low level flow not quite as strong as in other recent events...amounts will also drop off notably with eastern extent...with additional amounts of 5-10" confined to the far western/southwestern sections of Wyoming and Genesee counties respectively. It should be noted that these totals reflect the expected migratory nature of the band...
with locally higher amounts than this possible should it hold in place over an area for longer than currently expected.

Off Lake Ontario...lake snows extending from the northern Tug Hill region to just south of Watertown this morning will also push back northward again to the Watertown area late this morning and early this afternoon as winds back again to the west-southwest...then will wobble about in this general area until early this evening...when veering of the flow following the trough passage will send the lake snows back southward to the Tug Hill. Fairly intense lake snows should then linger across the Tug Hill through the early overnight hours...before also beginning to weaken and retract back toward the Oswego county shoreline overnight as ridging/drier air/lowering inversion heights begin to arrive
This being said
a nice little convergent boundary should still help to keep some moderately heavy snow going in the vicinity of Mexico Bay into Wednesday morning.

With respect to accumulations...have also significantly raised these east of Lake Ontario...where as much as another 2 to 3 feet will be possible through tonight in between the far northern portion of the Tug Hill and just south of Watertown...with the Watertown area itself likely to see additional accumulations approaching 2 feet.

SHORT TERM /WEDNESDAY THROUGH THURSDAY/
A shortwave trough rounding the base of the longwave trough Tuesday will help pivot an pull the deep longwave trough further east Tuesday night and eventually into the Atlantic Ocean Wednesday. This will place the trough axis across the region Tuesday night along with its associated even colder arctic airmass to spill across New York State, bottoming out 850mb temperatures towards -25C and supporting a very cold night. Lows Tuesday night will plummet well below zero across much of the area, supporting wind chill values to range in the teens below zero and some twenty below zero values across the higher terrain. In addition to temperatures, ongoing lake effect east of both Lakes Erie and Ontario will continue throughout Tuesday night, gradually weakening heading into Wednesday morning.

Now with zonal flow aloft, and surface ridging nudging northward into the region Wednesday, some associated subtle warm air advection combined with the introduction of dry air will cause lake induced equilibrium levels to fall, thus resulting in the weakening of lake effect snows. However, with the surface ridge nudging northward into the region, winds will veer further south-southwest and shift snows across the areas northeast of the lakes throughout the course of the day. By Wednesday afternoon, lake effect activity will like north of both the Buffalo and Watertown metros.

As the weak ridge slides east towards and eventually off into the Atlantic Wednesday night into Thursday, weak low level troughing will slide across the western and central portions of the Great Lakes, resulting in a surface low to slide northeast from the central Great Lakes towards southern Quebec and introducing a frontal boundary to the western edge of the forecast area. Ahead of this frontal boundary, expect warm air advection modulating temperatures Thursday to warm up into the low to mid 20s. With the frontal boundary remaining along the western edge of the area a chance of snow showers is possible across WNY, with the area likely remaining dry.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
850mb temperatures will likely remain favorable to support lake effect snow throughout much of the end of the week into the start of the new work week. A passing shortwave trough late Thursday night into the start of Friday will result in an increase of low level moisture, thus increasing the chances for a lake response off of both lakes. With west-southwesterly flow will support these lake showers east of both Lakes Erie and Ontario.

With the trough exiting to the east and a ridge building into the region Friday night into Saturday morning, low-level flow will back further southwesterly and support lake bands to shift north. As a surface ridge slides east into the Atlantic Saturday, lake effect activity will peter out throughout the day as dry air is introduced into the area.

A surface low well north in Canada will slide a surface frontal boundary east across the Great Lakes region Saturday night through Monday, supporting chances for snow showers to spread across the area, with some lake enhancement possible east of the lakes.

Temperatures will gradually modulate back towards normal for late January.

AVIATION /09Z TUESDAY THROUGH SATURDAY/
Lake snows will continue to produce LIFR/IFR conditions east and northeast of the lakes through the TAF period...with these weakening and retracting back closer to the lakeshores from west to east as we push through Tuesday night and surface high pressure/drier air begins building across the region
Outside of the lake snows
conditions will be VFR.

Off Lake Erie...the lake snows will primarily affect areas between KJHW and KBUF into this morning...before lifting northward later this morning and this afternoon. This should bring some LIFR/IFR to KBUF this afternoon...with a few snow showers spraying off the edge of the band possibly bringing some brief MVFR to KIAG/KROC during the afternoon and evening. The band will then settle back south late this afternoon and night...resulting in conditions at KBUF returning to VFR this evening...and some MVFR developing at KJHW later on tonight.

Off Lake Ontario...the lake snows will slip back south to areas from the Tug Hill to just south of Watertown through daybreak. This will result in some temporary improvement to IFR/MVFR at KART...before the band lifts back north again this afternoon and brings another round of LIFR to KART that should last until later this evening.
After that the band will slip back south and weaken again through the remainder of tonight...with conditions at KART improving back to VFR.

Outlook...

Wednesday...Lake effect snow east of the lakes and attendant IFR/MVFR lifting northward and dissipating...with mainly VFR conditions elsewhere.
Thursday...Mainly VFR. Some weaker lake effect snow and reductions possible northeast of the lakes later on in the day.
Friday and Saturday...Restrictions possible downwind of the lakes in lake effect snow.

MARINE
A prolonged period of Small Craft Advisory conditions will occur on Lake Erie and Lake Ontario through much of the week as one of the coldest airmasses of the season, and in a few years for that matter passes over the eastern Great Lakes. As such the combination of cold temperatures and breezy winds will bring freezing spray to Lake Erie and Lake Ontario as well from time to time through Thursday morning.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Cold Weather Advisory from 7 PM this evening to 11 AM EST Wednesday for NYZ001>005-010-011.
Cold Weather Advisory until 11 AM EST Wednesday for NYZ006-008- 012>014-019>021-085.
Lake Effect Snow Warning until 1 PM EST Wednesday for NYZ006.
Lake Effect Snow Warning until 7 AM EST Wednesday for NYZ007- 008.
Lake Effect Snow Warning until 4 AM EST Wednesday for NYZ010- 011.
Lake Effect Snow Warning until 10 AM EST Wednesday for NYZ012- 019-020-085.
MARINE...Small Craft Advisory until 5 AM EST Wednesday for LEZ040-041.
Heavy Freezing Spray Warning until 1 AM EST Wednesday for LEZ040-041.
Small Craft Advisory until 5 AM EST Wednesday for LOZ042.
Heavy Freezing Spray Warning until 7 AM EST Wednesday for LOZ042>045-062>065.
Small Craft Advisory until 1 PM EST Wednesday for LOZ043- 044.
Small Craft Advisory until 7 PM EST Wednesday for LOZ045.