Marine Weather and Tide Forecast for Rochester, NY

KEY MESSAGES
1) Light lake effect snow showers will linger through tonight with very minor additional accumulations.

2) Clipper low will bring light snowfall Friday night, mainly east of Lake Ontario.

3) Warmer temperatures are expected next week with increasing chances for rain and movement of ice on area creeks and streams by midweek.

DISCUSSION
KEY MESSAGE 1...Light lake effect snow showers will linger through tonight with very minor additional accumulations.

Low level northwest flow of cold air will continue to support limited lake effect and upslope snow showers through tonight.
Forecast soundings show low inversion heights around 5K feet this evening. Despite the low inversion height, a shallow unstable boundary layer and a few thousand feet of dendritic snow growth within the cloud bearing layer will continue to support a weak lake and upslope response tonight.

Widespread flurries and light snow showers this evening will gradually diminish in areal coverage overnight, but may linger across the higher terrain east of Lake Erie and across areas southeast of Lake Ontario through Friday morning before inversion heights fall to the point that the dendritic growth zone is eliminated.

Additional accumulations will be very minor, less than an inch in most areas. A few isolated fluffy 1-2" reports cannot be ruled out across the higher terrain and southeast of Lake Ontario.

KEY MESSAGE 2..Clipper low will bring light snowfall Friday night, mainly east of Lake Ontario.

A fast moving shortwave trough will track southeast across Ontario Friday. Associated weak surface wave will move through New York State Friday night and early Saturday. Increasing moisture and lift ahead of the wave will bring a light snowfall, mainly to areas east of the Finger Lakes and North Country. Best accumulations on the order of 1-2" expected where there is upslope enhancement across the higher terrain east of Lake Ontario Tug Hill. NBM/LREF probabilities showing less than a 20% for greater than 2" snow.

KEY MESSAGE 3...Warmer temperatures are expected next week with increasing chances for rain and movement of ice on area creeks and streams by midweek.

A strengthening upper ridge will shift off the East Coast by midweek, while a strengthening area of low pressure emerges over the Northern Plains and Midwest, which will then track eastward into the Great Lakes. This pattern shift will result in a warming trend through midweek next week. Chances for precipitation will increase by midweek, and while there remains uncertainty in precipitation type east of Lake Ontario, further west plain rain will be heavily favored.

Temperatures should average above normal starting Saturday, eventually topping out in the 40s for most areas south of Lake Ontario for the better part of next week. This temperature trend will be warm enough to push the thawing degree hours well over 300 for most, if not all of the forecast area. Far too soon to determine any specific hydrological impacts, but at least some breaking up and movement of ice on area waterways is expected.
Will need to monitor the potential for ice jams. Some ensemble guidance brings a few Buffalo area creeks into action stage or higher by mid next week.

AVIATION /00Z FRIDAY THROUGH TUESDAY/
Cold northwest flow beneath a shallow inversion will continue to support light lake effect and upslope snow showers tonight. The widespread light snow this evening will diminish in areal coverage overnight, but may still linger into Friday morning southeast of Lake Ontario and across the higher terrain of the western Southern Tier and Finger Lakes. Expect mainly MVFR VSBY and CIGS within lake effect areas, although a few pockets of IFR will also occur in more persistent snow showers.

Lake effect and upslope clouds with areas of MVFR CIGS Friday morning will give way to mainly VFR in the afternoon. A mid level shortwave and clipper system will then cross the eastern Great Lakes Friday night, bringing another period of IFR in light snow along with MVFR/IFR CIGS.

Outlook...

Saturday...Local MVFR/IFR in snow showers early east and southeast of Lake Ontario, improving to VFR.

Sunday through Tuesday...Mainly VFR.

MARINE
Northwest winds will continue to produce choppy conditions on Lake Ontario through tonight.

The next chance for small craft conditions will arrive for Friday afternoon into Saturday morning as a clipper low dives south toward the lakes.

Surface high pressure builds into the lower great Lakes Saturday afternoon bringing lighter winds through Saturday night. Another fast moving clipper dives towards the region Sunday which may bring a brief period of near Small Craft conditions.

Please note...Most, if not all of the Lake Erie nearshore waters are ice covered. Waves have been omitted from the forecast.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...None.