Marine Weather and Tide Forecast for Irondequoit, NY

KEY MESSAGES
1) Widespread rain will continue across the region tonight, with freezing rain across the Saint Lawrence Valley and Tug Hill, and south of Lake Ontario.

2) A strong cold front will bring a round of widespread rain showers and possibly a few thunderstorms Saturday.

3) Increased risk for flooding through next week, mainly across the North Country, as a result of above average temperatures and multiple rounds of rain.

DISCUSSION
KEY MESSAGE 1...Widespread rain will continue across the region tonight, with freezing rain across the Saint Lawrence Valley and Tug Hill, and south of Lake Ontario.

Surface temperatures have dipped below freezing for many locations along the southern shore of Lake Ontario (Niagara County to Wayne County), and into Genesee and Wyoming counties and the far northern portion of Erie county. A persistent northeast wind, nightfall, and steady rain will maintain temperatures below or near freezing overnight. Freezing rain will likely cause roads, especially bridges and overpasses to become slick and hazardous. A Winter Weather Advisory is in effect until 5AM Friday, when precipitation is expected to be east of the region. Freezing drizzle and fog will linger overnight.

A compact, progressive shortwave moving across the Midwest with an expansive precipitation shield across the lower Great Lakes this evening. Widespread precipitation will continue tonight before quickly exiting off the eastern seaboard Friday morning.

Surface temperatures this evening show 40s across southwest NY to the upper 20s across the Saint Lawrence Valley and a range of 30s in between. The colder temperatures in the low-levels will support freezing rain tonight. A Winter Weather Advisory remains in effect for Jefferson and Lewis counties late today through Friday morning where one to two tenth of an inch of ice is expected, especially across northern Jefferson Co within the Saint Lawrence Valley.

KEY MESSAGE 2...A strong cold front will bring a round of widespread rain showers and possibly a few thunderstorms Saturday.

A positively tilted mid-level shortwave will peel off the Rockies and slide across the north-central Plains and upper Great Lakes Friday night, then continue to move across the Great Lakes Saturday through Saturday night. This will force an attendant sfc low to strengthen as it glides northeast from the Upper Midwest to southern Quebec, which will in turn drag a strong 50-60kt southwesterly LLJ east across the forecast area. First off, scattered showers will develop late Friday night into early Saturday morning in the vicinity of the warm front lifting north across western NY.
Lingering cloud cover through the morning will limit boundary layer warming and instability available across the warm sector for any isolated convection. The main focus for rain and a few thunderstorms will be closer to the front mid-afternoon Saturday into the early evening with precipitation chances ending Saturday night from west to east behind the front.

Latest SPC Outlook for Day 3 does highlight portions of western NY under a Slight Risk (2/5) for severe thunderstorms. Despite limited instability up to around 500 J/kg, strong bulk shear values will be impressive around 45 kt. With strong kinematics with this system, any thunderstorms that develop could have the potential for locally strong winds. One limiting factor will be the influence of our cold lakes on the low-level environment. Convective inhibition will be strong immediately east and northeast of Lake Erie likely limiting any stronger cells from developing. Current thinking is the main focus for stronger storms would be across the western Southern Tier into the western Finger Lakes region, but the axis of limited instability quickly runs out farther to the east.

KEY MESSAGE 3...Increased risk for flooding through next week, mainly across the North Country, as a result of above average temperatures and multiple rounds of rain.

While some day-to-day variability is expected, temperatures over the next 6 to 7 days will be above average for early/mid March with several rounds of precipitation expected. Long range ensemble guidance and WPC forecast about 1.5-3" of QPF across the eastern Great Lakes over the next 7 days. While some of this will fall as a wintry mix at times across the North Country, the warmer temperatures will cause most of this QPF to be in the form of plain rain across the region.

This pattern will lead to rises on most area waterways with an increased threat for flooding as the rainfall combines with accelerated snowmelt runoff. Based on the limited amount of SWE and antecedent water levels well below Action stage however, the threat for flooding should be very limited for the waterways across WNY.
East of Lake Ontario however, a very different story as recent SWE surveys have measured over 10" of liquid in the snowpack across the Tug Hill. This could lead flooding along the Black River and other rivers that drain the western Adirondacks and Tug Hill Plateau.
MMEFS guidance suggests water levels on the Black River should begin to rise Friday and crest near the middle of next week, but remain at odds with maximum crest height in spots such as at ARTN6 (Black River at Watertown). At the very least, elevated flows to at least Action stage appear likely, though confidence in higher rises to flood stage remains low.

AVIATION /00Z FRIDAY THROUGH TUESDAY/
Widespread rain and freezing rain will move across the region this evening, tapering off from west to east overnight. Surface temperatures are near or below freezing south of Lake Ontario into the Genesee and Wyoming counties as well as the Saint Lawrence Valley and freezing rain is likely at KIAG, KGVQ, and KROC terminals and may be brief at KBUF. Freezing rain is also expected at KART.
Elsewhere, light to moderate rain is expected across the region.

Flight conditions will continue to deteriorate to IFR/LIFR this evening, with MVFR across the North Country (KART.) As precipitation tapers off from west to east tonight, fog and low stratus will continue through the overnight hours.

IFR/LIFR will linger from the Genesee Valley/Finger Lakes region westward through the morning hours, with mainly MVFR east of Lake Ontario. Some drier air working in is expected to bring at least some improvement through the second half of the day.

Outlook...

Saturday.. MVFR/IFR with rain showers and a slight chance of thunderstorms.

Sunday.. MVFR/IFR becoming VFR.

Monday and Tuesday...Mainly VFR with a chance of rain showers Tuesday.

MARINE
An area of low pressure continues to approach from the Ohio Valley, while a strong Canadian high is positioned over Central Quebec today. This has caused tightening pressure gradients between these two features with a moderate east-northeasterly breeze across Lake Ontario. Fresh to strong breezes expected to last into tonight before slowly tapering off by Friday morning as the pressure gradient weakens.

SCAs remain in effect for the western two-thirds of the southern Lake Ontario shoreline from the Niagara River east to Sodus through Friday morning.

Please note...most, if not all of the Lake Erie nearshore waters continue to be ice covered. Waves have been omitted from the forecast.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Winter Weather Advisory until 5 AM EST Friday for NYZ001>004- 010>012.
Winter Weather Advisory until 1 PM EST Friday for NYZ007-008.
MARINE...Small Craft Advisory until 10 AM EST Friday for LOZ042.
Small Craft Advisory until 7 AM EST Friday for LOZ043.