Marine Weather and Tide Forecast for Ontario, NY

KEY MESSAGES
1) Warm with rounds of showers and thunderstorms through much of the week.

2) Marginal risk for isolated severe thunderstorms and locally heavy rainfall through Wednesday.

DISCUSSION
KEY MESSAGE 1...Warm with rounds of showers and thunderstorms through much of the week.

Broad ridging will remain in place across the eastern CONUS through the end of the week...with a parade of shortwave impulses (some convectively-enhanced) rippling northeastward along the periphery this ridge and across our region
In the process
these features and their associated weak to modest surface lows will track northeastward along a persistent frontal zone draped across the Great Lakes and Northeast...causing this boundary to waver north and south while also generating frequent rounds of showers and scattered thunderstorms.

Digging more into the forecast details...the first in the series of these waves is now in the process of Southern Ontario...with the last of its initial round of convection now in the process of crossing the North Country. As we push through the afternoon and the attendant surface low pushes east into the Saint Lawrence Valley...
it will swing its trailing cold front southeastward across our area.
Coupled with convergence along a lake breeze boundary setting up to the lee of Lake Erie and diurnal heating...this will likely lead to another round of convection from the Southern Tier northeastward across the Finger Lakes and into central New York...while further north the stabilizing flow off the cooler waters of Lakes Erie and Ontario should lead to a much lower chance of storms across the lake plains. This next round of convection should then die out fairly quickly early this evening with the loss of heating/departure of the cold front and collapse of the lake breeze boundary...with a relative lull then following for the balance of the evening.

Overnight and Wednesday we'll get to do things all over again as yet another convectively enhanced shortwave and surface low/attendant warm frontal segment makes its way across the central Great Lakes and southern Ontario. This will bring another round of fairly widespread warm-frontal showers and scattered thunderstorms that will cross our region from west to east between later tonight and the first part of Wednesday morning. Following the passage of these we can expect another relative lull between the mid morning and early afternoon hours...before the trailing cold front/developing lake breeze boundaries/diurnal destabilization lead to another round of showers/scattered thunderstorms during the afternoon...with the greatest convective potential again likely to lie across areas inland from lake breeze boundaries.

Wednesday night through Thursday night it'll be more of the same as a stronger mid-level shortwave trough and surface low will track from the Upper Midwest to southern Ontario, then into New England...
resulting in yet another warm frontal/cold frontal passage with each of these features accompanied by additional rounds of showers and thunderstorms
By Friday
the guidance diverges some with how quickly this system departs...with it possible that at least some showers/a few storms could linger into at least part of Friday...
especially across eastern portions of the area.

KEY MESSAGE 2...Marginal risk for isolated severe thunderstorms and locally heavy rainfall through Wednesday.

Numerous rounds of showers and thunderstorms will cross our region through Wednesday, with a few of these rounds potentially bringing a risk of isolated strong wind gusts and locally heavy rainfall.

The next of these should affect areas primarily from the southern Tier northeastward across the Finger Lakes into central New York...
along and ahead of an advancing weak cold front and to the lee of more stable lake shadows off both lakes
Within this area
developing weak to moderate surface-based instability and strong/ largely unidriectional flow aloft may support a low risk for some isolated strong wind gusts. This round of convection and any severe risk will end by early this evening with the departure of the cold front/collapse of any lake breeze boundaries and diminishing instability.

Later tonight and Wednesday morning...the next convectively-enhanced shortwave/surface low and warm frontal segment will approach and cross our area from west to east along with another round of widespread showers and scattered thunderstorms. While not at a favorable time of day...a few of the above storms could still pose a risk of locally strong wind gusts if any bowing segments from upstream manage to persist as these cross our region. In the wake of this round of convection...diurnal heating should again allow weak to moderate instability to develop inland from developing lake shadows...with the associated lake breeze boundaries and the approach of yet another weak cold front combining with this to yield yet another round of showers/storms during the afternoon. The greatest coverage of these will again likely lie from the Southern Tier across the Finger Lakes...with a strong and mostly unidirectional flow aloft again supporting a risk for mainly isolated strong/damaging wind gusts
This said
low level shear will be a bit greater than today and may support a low...but also nonzero risk of an isolated tornado across the Southern Tier...where available instability looks to be the greatest.

Finally...PWATs will be in the 1.25-1.50 inch range at points. While a continued fast flow aloft should help to keep any storms moving along and any flooding risk on the lower side...any training of storms could result in a localized flash flood risk should the latter develop.

AVIATION /18Z TUESDAY THROUGH SUNDAY/
Scattered showers and thunderstorms will continue across the area today, with brief heavy downpours at times as well. CIGs /VSBY to IFR and possibly LIFR at times within heavier showers/storms.
Thunderstorms will have the potential to produce gusty winds and hail at times through the evening. Outside of showers/storms mainly VFR or higher end MVFR for the afternoon hours.

Tonight, scattered showers and thunderstorm potential will continue through the evening. A batch of showers and thunderstorms will move through the area during the second half of the night. Moderate to at times heavy downpours will be possible with any showers/storm.
Flight conditions through the evening and early overnight mainly in the higher end MVFR to VFR is expected. Flight categories will lower to IFR and at times LIFR will be possible with the steadier showers/storms during the second half of the night. Again, any storms could produce some gusty winds and locally heavier downpours at times.

Outlook...

Wednesday through Thursday night...VFR/MVFR with some local IFR at times. Numerous rounds of showers and scattered thunderstorms.

Friday...VFR/MVFR with showers possible.

Saturday...Mainly VFR with a chance of showers later in the afternoon.

Sunday...A mixture of MVFR/IFR with rain showers mixing with and changing to snow through the day.

MARINE
SCA-level conditions across eastern Lake Erie...the Niagara River...and western Lake Ontario will diminish quickly late this afternoon and early evening as the pressure gradient across our region weakens.

Rounds of showers and scattered thunderstorms will cross the lower Great Lakes today through Thursday. A few storms may produce locally higher winds and waves along with lightning strikes.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...Small Craft Advisory until 7 PM EDT this evening for LEZ020- 040-041.
Small Craft Advisory until 7 PM EDT this evening for LOZ030-042.