Marine Weather and Tide Forecast for Cape Vincent, NY

KEY MESSAGES
1) Warm with rounds of showers and thunderstorms through Thursday.

2) Severe thunderstorms remain possible through Thursday, with locally heavy rainfall also possible through tonight.

3) The very warm pattern continues through Saturday before much colder air arrives by early next week.

DISCUSSION
KEY MESSAGE 1...Warm with rounds of showers and thunderstorms through Thursday.

Our unsettled pattern will continue through Thursday with a persistent frontal zone remaining in place across the Great Lakes and Northeast...with multiple shortwave impulses (some convectively enhanced) and their associated surface reflections rippling northeastward along the frontal zone and causing it to waver about...while also generating additional rounds of showers and thunderstorms.

Currently our region is in between rounds of convection...with the all-but-dead remnants of some earlier upstream showers/storms crossing the Niagara Frontier in the form of some sprinkles or very light showers. As we push through the rest of this afternoon the combination of increasing diurnal instability and localized convergence along the southern edge of the Lake Erie lake breeze may allow for some scattered to briefly numerous showers and storms to initially develop across the southern Tier and interior of the Finger Lakes...before an upstream MCV (currently over Indiana)
begins encroaching upon the area from the southwest early this evening. Better forcing attendant to this feature will combine with lingering instability to produce a round of numerous to fairly widespread showers and storms across areas south of the NYS Thruway during the early to mid evening hours...with the areal coverage of the pcpn/pcpn potential diminishing with further northward extent elsewhere.

Following the passage of the MCV...we'll likely experience another relative lull in convective potential through the late evening and early overnight hours...with some additional warm advection-driven showers and scattered storms then possible overnight into early Thursday in association with another wave of low pressure making its way into the central Great Lakes and its attendant warm front. With the latter...have confined PoPs to likely or lower for now given the poorer agreement on the timing/placement of convection seen in the shorter-term guidance.

Thursday and Thursday evening...the aforementioned surface wave and its parent mid-level shortwave trough will make their way east and across our region...and in the process will push the frontal boundary southeastward across our region as a cold front during the afternoon and evening. With modest to moderate instability developing out ahead of the front...the combination of low level convergence along the front/localized lake breeze boundaries and DCVA/height falls aloft should have little trouble generating another round of fairy widespread showers and thunderstorms during the afternoon and early evening hours...with the convection then fading from NW-SE during the evening with the loss of heating and the passage of the cold front. This system will then depart off to our east later Thursday night and Friday...with any leftover spotty showers at the start of Friday giving way to a mainly dry and somewhat cooler day (though temps will still be well above normal)
as narrow ridging both at the surface and aloft builds across our region.

KEY MESSAGE 2...Severe thunderstorms remain possible in some areas through Thursday, with locally heavy rainfall also possible.

Through Thursday/Thursday evening there will be two main windows for potentially strong to severe thunderstorms. The first of these will be this evening south of the NYS Thruway (more so across the Southern Tier) in association with passage of the above mentioned MCV. Provided enough of a reservoir of instability remains to allow the stronger convection with this feature to extend northward into our area...the accompanying stronger forcing/increased shear may be supportive of a few strong to damaging wind gusts...as well as a lower but nonzero potential for marginally severe hail and/or an isolated tornado.

The second opportunity for strong to severe thunderstorms will be Thursday afternoon and evening...in tandem with the approach/passage of the main shortwave trough/cold front and an accompanying enhanced swath of low-mid level flow. With modest to moderate instability likely to develop across the region out ahead of the cold front (particularly from the Genesee Valley/Finger Lakes eastward into central NY)...the dynamic/kinematic forcing from the above features should be sufficient for at least some stronger multicellular convection and possibly even a few supercells...with damaging wind gusts again the primary hazard
This being said
large hail and an isolated tornado or two again cannot be ruled out...particularly from the Genesee Valley/Finger Lakes eastward to central NY where instability should be greater.

Finally...there will also be a lower-end potential for excessive rainfall/flooding through Thursday given the moist ground conditions and PWATs of 1.25/1.5"...though given the fast flow aloft and resultant expected quick storm motion this would likely only be a concern if any areas of training were to develop.

KEY MESSAGE 3...The very warm pattern continues through Saturday before much colder air arrives by early next week.

Well above normal temperatures will continue through Saturday as our region will remain in the warm sector of a deepening trough over the Upper Great Lakes/an associated surface low making its way to near James Bay. Temperatures will soar into at least the mid to upper 70s...with 80s a possibility if clouds and showers hold off long enough. The strong cold front trailing from the low will then plow across our region late Saturday afternoon and night while generating another round of widespread showers and thunderstorms...
some of which could be severe depending upon the exact timing of the front/amount of instability in place.

In the wake of this front...deep upper level troughing and a much colder airmass will overspread our region Sunday through Monday...
with 850 mb temps plunging into the -10C to -14C range by late Sunday night/early Monday. This will rudely send temperatures back down to levels more typical of March...with the cold airmass and northwest flow regime also supporting lake effect and upslope snow showers in a northwest flow regime Sunday night through Monday morning
This being said
moisture appears limited and the favorable synoptic scale setup is rather brief, so any accumulations will be minor. Highs Monday will only be in the upper 30s/lower 40s at best, and may stay in the 30s areawide if clouds persist most of the day.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/
Heading into the afternoon, lingering low level clouds persist across the eastern Lake Ontario region this afternoon, supporting the only IFR conditions region. Otherwise in the wake of this morning's line of thunderstorms, conditions across the remainder of the area have improved to VFR, supporting destabilization and gusty winds with southwest to westerly winds gusting between 25 to 35 knots across Western New York and the Genesee Valley.

The next round of convection will move in from west to east in the next few hours, with the best timing of arrival being around 21Z. A few thunderstorms may become severe, with the best location for severe weather lying between KJHW to KELZ. Storms across the Southern Tier will likely produce severe gusts. Additionally an isolated tornado can't be ruled our and a lesser chance for severe hail. Showers and storms will likely remain within the vicinity of the Southern Tier tonight, with ceilings to deteriorate to IFR areawide.

Outlook...

Thursday and Thursday night...VFR/MVFR with some local IFR possible at times due to numerous rounds of showers and scattered thunderstorms.

Friday...VFR/MVFR with showers possible.

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

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

Monday...Improving to VFR/MVFR. Lingering lake enhanced snow showers and clouds gradually dissipate.

MARINE
Multiple rounds of showers and thunderstorms will cross the lakes through Thursday, a few of which may produce strong surface wind gusts and locally higher waves. Otherwise the warmer airmass and relatively cold lake temperatures will result in limited mixing of synoptic winds...thereby precluding any real risk of advisory-level conditions.

Relatively light winds and minimal wave action are then expected later Thursday night and Friday as high pressure builds across the Lower Great Lakes...before winds increase out of the south/southwest Saturday/Saturday night in association with the approach/passage of a strong cold front. This may result in the next round of SCA conditions with the frontal passage also accompanied by another round of showers and storms...some of which could produce locally stronger winds and higher waves.

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