Marine Weather and Tide Forecast for East Rochester, NY

NEAR TERM /THROUGH TUESDAY NIGHT/
...HEAVY LAKE EFFECT SNOW EAST OF LAKE ERIE AND LAKE ONTARIO THIS AFTERNOON THROUGH TUESDAY...

As of 4 pm lake effect snow continues east of both lakes...with the Lake Erie band having nudged a little further north over the past couple of hours...with its northern portion now bringing some briefly moderate snow to the Buffalo Airport. Lake induced equilibrium levels are not particularly high this afternoon and evening, averaging around 7K feet over both lakes. Despite the shallow inversion heights and limited synoptic scale moisture, a healthy lake response has developed off both lakes. A mid level trough will move southeast across the area late Tuesday. Lake induced equilibrium levels will briefly rise to over 10K feet just head of the trough axis as moisture deepens, large scale ascent increases, and the coldest air aloft crosses the area.

Outside of lake effect areas, a few flurries and light snow showers this afternoon will end this evening, with mainly dry weather and even some breaks in the clouds overnight through Tuesday.

It will be quite windy this afternoon through Tuesday, with gusts of 25-35 mph common across the area, strongest on the lake plains. This will continue to generate some blowing and drifting snow in lake effect areas.

Off Lake Erie...

As mentioned above...the band of moderate lake effect snow has edged a bit further north over the past couple of hours...and is now bringing a period of moderate snow to the Buffalo Airport. Upstream radar data and model guidance suggest that the band is now likely near its northernmost extent...and should begin slipping back southward through the early evening hours...allowing the band to again focus more on central Erie County and inland along the Genesee/Wyoming County border by early evening. Snowfall rates are not particularly high, around 1" per hour in the heart of the band this afternoon and evening.

Boundary layer flow will veer to more due west late this evening and overnight. This will carry the band of lake effect snow southward across southern Erie/Wyoming counties starting mid to late evening, reaching the western Southern Tier overnight. Snowfall rates will remain similar, around 1" per hour.

Tuesday, boundary layer flow will back a little to the WSW ahead of an approaching trough, which will likely move the lake band north from the western Southern Tier back into southern Erie/Wyoming counties from late morning through early to mid afternoon. Snowfall rates of 1-2" per hour are likely Tuesday as inversion heights rise.
A sharp mid level trough along with a surface reflection will cross the eastern Great Lakes late Tuesday afternoon and evening, with boundary layer flow quickly veering to the northwest. This will carry lake effect snow back southward into the western Southern Tier. Tuesday night, lake effect will evolve into a northwest upslope flow event along the Chautauqua Ridge and Boston Hills, along with an upstream Lake Huron connection meandering across the Southern Tier.

Off Lake Ontario...

Lake effect snow continues to slowly consolidate into a more narrow/cohesive band just south of Watertown...where it should linger into early this evening before also starting to slip a little further southward toward the Tug Hill region. Expect snowfall rates of around 1" per hour through this evening.

Later this evening and overnight, boundary layer flow will veer to due west, carrying the lake effect snow southward to center on the Tug Hill Plateau region. The band will remain in this same area, with subtle north/south oscillations overnight through mid to late afternoon Tuesday. The band will also intensify as convergence improves over the lake and inversion heights rise. Expect snowfall rates to increase to 2-4" per hour late tonight through Tuesday, especially over the western slopes of the Tug Hill Plateau with an added boost of upslope flow.

Late Tuesday afternoon and evening, the passing trough will quickly veer boundary layer flow to the northwest. This will carry the lake effect snow southward across Oswego County, with still intense 2-3" per hour snowfall rates. The band will move farther southwest overnight into portions of Wayne/Cayuga counties and weaken as the fetch shortens and inversion heights quickly fall after the trough passage. Expect locally moderate accumulations across eastern Wayne and northern Cayuga counties overnight Tuesday night.

As far as accumulations go, still expecting storm totals of 10 to 20 inches in the most persistent bands off Lake Erie from Southern Erie and western Wyoming counties southward into western Chautauqua and far northwest Cattaraugus counties. The Buffalo Southtowns will likely end up with 6-10" with most of that falling today into this evening.

East of Lake Ontario, expect small bullseye of 3+ feet in the middle of the Tug Hill Plateau, surrounded by 1-2 feet across southern Jefferson, northern Oswego, and western Lewis counties.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
... LAKE EFFECT SNOWS TO BEGIN TO PETER OUT EAST AND SOUTHEAST OF THE LAKES WEDNESDAY...

Mid-level ridging will begin to build in across the region Wednesday and Wednesday night. In its wake, the next mid-level trough will dive southeast across the Great Lakes Thursday.

Lake effect snow will be ongoing off both lakes Wednesday morning.
With low level winds now directed out of the northwest, lake snows will be directed southeast of both Lakes Erie and Ontario.

Off Lake Erie...

The ongoing band of lake snow Wednesday morning will likely be focused across Chautauqua county into southern Erie county, with the higher accumulations ranging across the higher terrain of the Boston Hills to the Chautauqua Ridge. Drier air working into the region and shorter fetch will begin to limit snowfall accumulations through the day Wednesday for most locations. There may still be a location or two that overachieve, if upstream connections locally enhance snowfall. Snowfall accumulations Wednesday will average between 2 to 3 inches.

Winds will veer to the southwest Wednesday afternoon acting to shift any lingering lake effect snow northeast of the lake. By Thursday morning expect light snow to focus over the Buffalo Metro and its Southtowns. An additional half of an inch to an inch of snow will be possible Wednesday night.

Off Lake Ontario...

A northwesterly flow will direct lake snows across Monroe, Wayne and northern Cayuga counties Wednesday morning, with the highest accumulations likely occuring south of the I-90. Due to the wind direction, lake effect bands will likely take on a more tea kettle effect (i.e. more multi band). Drier air working into the region and shorter fetch will begin to limit snowfall accumulations through the day Wednesday for most locations. There may still be a location or two that overachieve, if upstream connections locally enhance snowfall. Snowfall amounts will range between 2 to 3 inches, with a range of 1 to 2 inches possible closer to the lakeshore.

Winds will veer to the southwest Wednesday afternoon acting to shift any lingering lake effect snow northeast of the lake. By Thursday morning expect light snow to focus over the Buffalo Metro and its Southtowns. An additional half of an inch to an inch of snow will be possible Wednesday night.

As the next trough approaches the eastern Great Lakes Thursday, its associated cold front will slide from west to east across the area Thursday and Thursday afternoon. Any lingering lake effect snow will be reinvigorated and become lake enhanced northeast of both Lakes Erie and Ontario Thursday afternoon. Within the lake enhanced areas, expect another inch or two across both the Buffalo and Watertown Metros and a general dusting (up to a half of an inch) across the remainder of the area. Then in the wake of the front, lake enhanced snows will become pure lake effect bands and drift south across central and southern Erie county and the Tug Hill Plateau Thursday evening. The next mid-level ridge will begin to build across the Great Lakes late Thursday night, supporting warm dry air to filter across the region and act to dissipate lake snows by Friday morning.

LONG TERM /FRIDAY THROUGH MONDAY/
The axis of a mid-level ridge will work across the eastern Great Lakes Friday, then east of the area Friday night. What is left of any lingering lake induced snows on Friday will end as moisture further depletes and mid-level temps begin to modify (warm). All indications are Friday night should be fairly quiet, that is precipitation free ahead of an approaching cold front.

...Active weather returns Saturday, and then potentially turns much colder Sunday into next week...

A potent shortwave diving across the upper Midwest will carve out a broad and deep longwave trough across much of the CONUS. This will 'potentially' set the stage for an 'ARCTIC' airmass to visit the Lower Great Lakes bringing what looks like the coldest airmass (H850 T's -22C to -24C) of this winter season so far. There still remains a fair amount of details to work out, timing (arrival and departure)
of the front, and then several potential waves riding along this front, but it all depends on the model of choice (GFS, Canadian-NH, or ECMWF)
That said
it does look like it will become much colder beginning as early as Sunday behind the Arctic front. Lake effect snows will also come into play by Monday-Tuesday but confidence remains to low at this point to provide specifics
For now
have leaned on NBM guidance with chance to low end likely PoPs Monday and beyond
Otherwise
we will see above normal highs temps Friday and Saturday (low to mid 30s), then trend below normal (Sunday) to well below normal into next week (Monday and Tuesday).

AVIATION /21Z MONDAY THROUGH SATURDAY/
Moderate to heavy lake effect snow will continue this afternoon through Tuesday east of the lakes, with LIFR conditions in the bands of snow. Outside of lake effect areas, expect VFR conditions to prevail this afternoon through most of Tuesday. It will remain windy, with gusts of 25-30 knots much of the time.

Off Lake Erie, the band of snow will center just south of KBUF this afternoon and evening, with the northern edge of the band producing occasional light to moderate snow and IFR at KBUF. The band will move farther south starting mid evening, moving into the Southern Tier overnight. This will allow KBUF to improve to VFR, with IFR developing at KJHW. Tuesday, the band of snow will move back north away from KJHW in the morning, and should remain well south of KBUF.

Off Lake Ontario, a broad area of lake enhanced snow northeast of the lake this afternoon will consolidate into a more narrow band by late afternoon or early evening. Expect IFR at KART through much of the afternoon before the band moves south this evening. The band of snow will then settle farther south and center on the Tug Hill Plateau south of KART overnight through Tuesday.

Outlook...

Tuesday night through Wednesday...Areas of IFR in lake effect snow southeast of the lakes.

Wednesday night through Thursday.. MVFR/IFR with snow showers likely, especially east of the lakes.

Friday...VFR/MVFR with a small chance of snow showers.

Saturday.. MVFR/IFR with snow showers likely, possibly mixed with rain across lower elevations.

MARINE
Strong westerlies will continue this afternoon through Tuesday, with high end Small Craft Advisory conditions on Lake Erie and Lake Ontario. Winds will become northwest Tuesday night and Wednesday behind a trough, and start to diminish. Small Craft Advisory conditions may briefly end Wednesday afternoon, but winds will quickly increase again Wednesday night through Thursday as another trough crosses the eastern Great Lakes.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Lake Effect Snow Warning until 1 PM EST Wednesday for NYZ006>008.
Lake Effect Snow Warning until 4 AM EST Tuesday for NYZ010-011.
Lake Effect Snow Warning until 4 AM EST Thursday for NYZ012- 019-020-085.
MARINE...Small Craft Advisory until 4 AM EST Wednesday for LEZ020.
Small Craft Advisory until 7 AM EST Wednesday for LEZ040- 041.
Small Craft Advisory until 7 AM EST Wednesday for LOZ042-045.
Small Craft Advisory until 10 AM EST Wednesday for LOZ043- 044.