Marine Weather and Tide Forecast for East Rochester, NY

KEY MESSAGES
1) Cool and unsettled through the weekend with periods of lake enhanced rain showers.

2) Windy Sunday, especially across Western NY.

3) Somewhat milder weather returns early next week, followed by colder temperatures by the end of next week.

DISCUSSION
KEY MESSAGE 1...Cool and unsettled through the weekend with periods of lake enhanced rain showers.

A well defined mid level closed low will cross NY/PA today before reaching New England tonight. The associated surface low will weaken over the eastern Great Lakes today, giving way to secondary coastal cyclogenesis along the New England coast. The resulting coastal low will deepen as it moves from the Gulf of Maine tonight to the Canadian Maritimes by Sunday.

Strongly diffluent mid/upper level flow ahead of the closed low atop low level frontogenesis and convergence will continue to support an area of rain across Central NY today, gradually moving north and east across the North Country and Saint Lawrence Valley as the closed low moves east. Rain will persist much of the day in these areas as the best synoptic scale forcing pivots overhead.

Farther west, lake effect showers will continue this morning east of Lake Erie in convergent southwesterly flow just ahead of the closed low. The most persistent showers will be found along the Lake Erie shore through mid morning, with the northern extent occasionally reaching the Buffalo Metro area. There may be a few brief heavy downpours along the immediate lakeshore. The lake effect showers will tend to break up and weaken later this morning through the afternoon as the mid level closed low moves overhead and shear increases in the boundary layer.

Cool northwest flow will become established by early this evening as the coastal low deepens off the New England coast. Deep wrap around moisture on the western flank of the closed low will combine with lake induced instability and northwest upslope flow to support fairly widespread showers and light rain, peaking in coverage this evening through the early overnight. Boundary layer and surface temperatures will stay warm enough for all liquid, even across higher terrain. The deep moisture will quickly pull away late tonight through Sunday morning, with showers ending from west to east. The last of the showers across Central NY should end by mid morning Sunday.

Another progressive mid level closed circulation will dive southeast across Ontario and Quebec late Sunday through Monday morning.
Increasing moisture and synoptic scale ascent will combine with lake induced instability to support another round of rain showers developing Sunday evening and lasting through Monday morning. The lake enhancement will initially be found east of the lakes Sunday evening in westerly flow, moving southeast of the lakes overnight through Monday morning as boundary layer flow veers to the northwest. Boundary layer temperatures will continue to support all liquid.

KEY MESSAGE 2...Windy Sunday, especially across Western NY.

A tight pressure gradient will persist Sunday across the Great Lakes ahead of a potent and fast moving mid level closed low. Forecast BUFKIT soundings show 40-45 knots of flow in the boundary layer Sunday afternoon, with adequate low level lapse rates to support mixing of stronger winds aloft to the surface. The strongest winds will be found across the Niagara Frontier northeast of Lake Erie, where gusts will reach or exceed 40 mph at a minimum. There is some potential for a few hours of near 50 mph gusts during the time of peak mixing in the afternoon. A Wind Advisory may eventually be needed if it appears these higher gusts will be realized. Gusts across the remainder of the area will be in the 25-35 mph range.
Winds will diminish Sunday night as boundary layer flow veers to the northwest and the strongest winds aloft exit.

KEY MESSAGE 3...Somewhat milder weather returns early next week, followed by colder temperatures by the end of next week.

The pattern will become less active late Monday through the middle of next week as a WNW zonal flow develops across the northern tier of the CONUS. Dry weather will prevail much of the time, although shortwaves passing just north of the area combined with weak lake induced instability may support a chance of a few scattered showers at times, especially across the North Country. Temperatures will trend back to a little above average Tuesday through Wednesday.

The pattern will become more active again by the end of next week as a deep trough carves out over the Great Lakes and Northeast, evolving into a slow moving closed low by Friday and Saturday. In a general sense, this will bring a trend towards colder temperatures by the end of next week along with increasing chances for some rain and wet snow. There have been several individual deterministic model runs showing a stronger surface low and potential for an early season accumulating snowfall by Friday and Saturday. While such an event is within the realm of possibility, the airmass is not particularly cold and medium range models often show a cold bias at this time range early in the season. Rain with some minor higher elevation snow is a much more likely scenario, but model trends will continue to be monitored closely.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
A mid level closed low will cross NY/PA today before moving east into New England tonight. The combination of forcing and moisture from the closed low and lake enhancement will continue to support areas of showers today through tonight across the region.

Large scale forcing ahead of the closed low will continue to support an area of light rain through this morning across Central NY, gradually spreading into the North Country and Saint Lawrence Valley through the day. Farther west, lake effect rain showers will continue east/northeast of Lake Erie this morning, then tend to break up and weaken temporarily from late morning through mid afternoon. Areas of MVFR/IFR CIGS will continue today, especially across Central NY and the North Country, and the western Southern Tier. The lower elevations of Western NY and the western Finger Lakes including KBUF, KROC, and KIAG will stay mainly VFR through mid to late afternoon.

Tonight, cool northwest flow will develop as the mid level closed low moves off into New England and a secondary coastal low begins to deepen over the Gulf of Maine. Northwest upslope flow combined with lake instability will support widespread light rain and showers, peaking in coverage during the evening and early overnight.
Widespread MVFR CIGS will develop across lower elevations with IFR across higher terrain.

Outlook...

Sunday...A chance of showers across the Tug Hill region. VFR/MVFR CIGS early, improving to VFR. Windy, especially across Western NY.

Sunday Night.. MVFR/IFR with showers, especially east and southeast of the lakes.

Monday.. MVFR/IFR with showers likely in the morning, especially southeast of the lakes. Improving to VFR in the afternoon.

Tuesday through Wednesday...Mainly VFR. A chance of showers and MVFR across the Tug Hill region.

MARINE
Moderate westerlies will continue to produce Small Craft Advisory conditions along the nearshore zones east of Sodus Bay early this morning. Otherwise, there will be a temporary lull in winds through much of today as a mid level low passes overhead, and the associated surface low weakens over the lower Great Lakes.

A secondary surface low will develop today along the New England coast, then deepen as it moves into the Canadian Maritimes by Sunday. WNW winds will increase tonight as the low deepens, then become WSW Sunday and increase further, supporting high end Small Craft Advisory conditions on both lakes Sunday afternoon through Monday morning with sustained winds approaching 30 knots at times.

Cool air aloft and periods of lake enhanced showers will also support a chance of waterspouts today through Sunday morning.
Waterspouts typically develop in and near bands of lake effect clouds and showers.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...Small Craft Advisory until 7 AM EST Monday for LEZ040-041.