Marine Weather and Tide Forecast for Mexico, NY

KEY MESSAGES
1) Turning windy with showers and thunderstorms returning today. A few strong to severe storms are possible across Western NY this afternoon with a low-end flooding risk in certain areas.

2) Below average temperatures return late in the weekend, however more seasonal temperatures will arrive by Tuesday.

DISCUSSION
KEY MESSAGE 1...Turning windy with showers and thunderstorms returning today. A few strong to severe storms are possible across Western NY this afternoon with a low-end flooding risk in certain areas.

Our brief stretch of quiet weather will come to an end this afternoon. A closed low tracking into southern Hudson Bay will drive a powerful cold front into the eastern Great Lakes region with another round of widespread convection just ahead of it. Ahead of the wet weather, southerly winds will likely gust in the 30-40mph range in many areas. Embedded storms ahead of the front may be strong to severe across Western NY this afternoon.

Severe weather potential...

This incoming cold front is the same one that just produced a fairly prolific severe weather outbreak across the Plains and Upper Midwest yesterday afternoon/evening. However, the threat for our region today is comparatively lower, more conditional, and a bit more uncertain overall. With the new Day 1 Outlook, SPC has expanded the Slight Risk area further eastward to now cover most of WNY south of I-90.

A tricky setup in terms of how strong the storms will be as they move into WNY this afternoon, with considerations for and against severe weather potential. Strong dynamical forcing and elevated instability will likely maintain the primary line of upstream showers and storms all the way through the forecast area, and the arrival time will be favorable with peak diurnal heating of the afternoon. Across WNY, model soundings indicate strong mid to upper level flow with high 0-1km and 0-6km speed shear values, as well as dry low/mid levels with an "inverted-V". This suggests damaging winds will be the primary threat if any stronger storms or line segments manage to form, with a tornado or two unable to be ruled out.

Main sources of uncertainty stem from potential instability, as well as generally poor mid-level lapse rates less than 5.5C/km. Satellite imagery indicates a shield of blowoff cirrus and mid-level clouds expanding eastward. Upstream trends and HRRR guidance suggests this thicker cloud cover arriving in WNY right as peak diurnal heating begins, which may inhibit the amount of CAPE that manages to form ahead of the front today. Trends from most guidance packages have subsequently been lower the past few synoptic hour runs, as evidenced by very low REFS joint-probabilties for favorable CAPE, CIN, and 0-6km shear. This should, at a minimum, greatly reduce the potential for large hail. In addition, the exact nature of the shear profiles remains in question. Despite the low to the north strengthening, its northeastward track will pull the stronger low/mid-level winds away from the forecast area just as or before precip arrives. This leads to modeled SRH values also briefly lowering around onset time with only a brief window of optimal effective shear.

Excessive rainfall potential...

Flooding does not appear to be a significant concern today, though it will need to be monitored along with the severe potential. A less than ideal setup as the strong wind profiles today should allow the heavier showers and storms to move fairly quickly today. A narrow corridor of dewpoints in the upper 50s and PWATs of 1.25-1.5" should also support moderate, but not overly impressive rainfall rates.
Main concerns stem from sensitive antecedent conditons and the potential for bursts of moderate/heavy rain in areas of more complex terrain, such as in the Southern Tier, Finger Lakes, and perhaps the Tug Hill region.

KEY MESSAGE 2...Below average temperatures return late in the weekend, however more seasonal temperatures will arrive by Tuesday.

A pattern change is expected late this weekend as a deep upper level trough moves across the Great Lakes region and the Northeast. A return to well below normal temperatures and the chance for snow showers will begin this Sunday.

A west-northwest flow is expected across the region Sunday. Cold air advection and daytime heating will strengthen low-level lapse rates through the day. An increase in PVA and large scale ascent will move across the region. A mix of rain and snow showers is expected to develop across western NY with a focus of showers along a convergence zone from the Buffalo Metro to the Finger Lakes region.
Showers are also possible across the Saint Lawrence Valley through Sunday afternoon. A secondary cold front is expected to move through the region Sunday night with 850mb temperatures falling to -12C Monday. Snow showers are possible at times Sunday night through Monday. Little to no accumulation is expected.

A strong upper level ridge will build into the Plains and Mid-West through mid-week before moving into the Great Lakes region late in the week. Day-to-day warming is expected across the region.

AVIATION /07Z SATURDAY THROUGH WEDNESDAY/
VFR will prevail through at least 19z today as surface high pressure slides east of the region. Southerly winds will increase shortly after sunrise with widespread gusts 25-30kts anticipated. A few areas across Western NY may gust to near 35kts.

A strong cold front will then move into the region this afternoon with widespread showers and embedded thunderstorms. A period of MVFR to IFR conditions anticipated within this area of convection.
Confidence is low to moderate in the potential for strong localized wind gusts from KROC westward within storms that move into the region.

Following the passage of the front, cigs will deteriorate to MVFR/IFR this evening and through tonight. Showers will likely fill in behind the front, with rapidly falling temperatures supporting a mix with light snow after 06z.

Outlook...

Sunday/Sunday night...A mix of MVFR/IFR with upslope/lake effect rain showers mixing with and changing to snow showers.

Monday...Improvement to VFR with leftover scattered lake effect/upslope snow showers ending.

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

Wednesday...Mainly VFR.

MARINE
Relatively light winds and minimal wave action will continue through the early morning as high pressure moves from the lower Great Lakes into New England. Southerly flow will then increase today through tonight in association with the approach/passage of a strong cold front. This may result in the next round of SCA conditions for portions of the lakes with the frontal passage also accompanied by another round of showers and storms, some of which could produce locally stronger winds and higher waves.

A period of post-frontal stronger westerlies will then develop on Lake Ontario Sunday and persist through Sunday night with small craft conditions possible.

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