Marine Weather and Tide Forecast for Mayville, NY

NEAR TERM /THROUGH WEDNESDAY NIGHT/
Dry and cool weather will continue through the early overnight, with temperatures quickly falling through the 50s into the 40s by late this evening. Increasing clouds through the second half of the night will keep temps from falling much further, with most areas remaining in the 40s, which is seasonable for this time of year.

High pressure shifts east quickly tonight allowing an upstream occluding low pressure system and associated rain shield to advance into the southern Great Lakes/Ohio Valley. There is a plethora of dry air in the low and mid levels per the KBUF 5/21 @ 00Z sounding that will need to be overcome before any raindrops can make it to the surface, however the leading edge of the rain associated with a wing of warm advection and deeper moisture transport will start to move into the area from the southwest after midnight. This will allow the first wave of rain to start to develop across southwestern NY during the wee hours of the overnight, then spread northeast across areas south of Lake Ontario through midday/early afternoon or so as waves of rain are advertised to circulate northward around the nearly vertically stacked low nearing the western half of Lake Erie.
Meanwhile, expect just the chance for a few showers possibly making it into the North Country by later in the day as better moisture struggles to make it into that region. There will also be a small chance for a few embedded rumbles of thunder in the afternoon, mainly well south of the Buffalo Metro area across the Southern Tier where some limited instability may develop. A soaking rain is expected with rainfall amounts through Wednesday night expected to be around an inch for areas west of the Genesee Valley, with up to an inch and a half possible toward the NY/PA line. Lesser amounts expected across the eastern half of the area with basin averages of three quarters of an inch for the Genesee Valley and Finger Lakes region, tapering down to a quarter to one-third of an inch across the North Country furthest from the low. Daytime highs will remain below average with highs mainly in the 50s, with the warmest readings in the low 60s found toward the Watertown area where dry weather likely persists into the second half of the day, along with a southeasterly downslope flow off the Tug Hill.

Very little change Wednesday night as low pressure remains nearly stationary, wobbling about the lower Great Lakes region bringing continued periods of rain in across the region. Lows will again fall back into the 40s, with some upper 30s across the Tug Hill/western Dacks.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
The end of the work week will feature a deep, broad upper level trough across the eastern CONUS. Cool, dreary weather with periods of rain can be expected across western and north-central NY. A closed low over Lake Erie Thursday will slowly move east through Thursday night, before merging with a deep coastal low off the New England coast Friday. Deep moisture and large scale ascent will drive periods of rain across the forecast area Thursday. As the low moves overhead Thursday night, moisture will remain pooled across the forecast area and rain showers are possible. A lobe of DPVA will move south from Canada and the combination of deep moisture and large scale ascent will increase chances rain showers Friday into Friday night. 48-hr rainfall amounts will average 0.25-0.50" across the region.

Daytime highs will rise into the 50s Thursday, and the upper 40s to low 50s Friday. Lows will fall to the 40s Thursday night and Friday night.

LONG TERM /SATURDAY THROUGH TUESDAY/
A broad upper level trough will persist across the Northeast through the weekend. Moist, cyclonic flow will maintain chances for showers, especially during peak heating into into early evening. The upper level trough flattens out and moisture gets pulled away Sunday night through Monday. Mostly dry weather is likely Monday through Tuesday, however temperatures will remain below normal for late May.

Looking ahead, another closed low will likely move into the Ohio Valley mid-week next week. This will bring another period of unsettled weather and below normal temperatures to the region.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
High pressure over the area will maintain widespread VFR flight conditions through much of the overnight, although some low VFR (030- 050 kft) CIGS will continue across the North Country (KART).
Otherwise, mid and upper level decks will continue to thicken and lower from southwest to northeast as the ridge over the area breaks down and shifts east. A wing of warm advection associated with an occluding low pressure system moving into the Ohio Valley/southern Great Lakes will bring increasing shower chances toward the wee hours of the morning across the western Southern Tier (KJHW), then progress northeastward, with a few showers possibly getting into portions of the Niagara Frontier by daybreak. As low level moisture continues to increase, this may also introduce some MVFR CIGS into the Southern Tier (KJHW) by late tonight as well.

As the occluding area of low pressure only slowly moves north from Ohio to the central Lake Erie basin on Wednesday, expect deteriorating flight conditions as an initial wave of rain associated with a wing of warm advection moves further northeast into our area through the morning hours bringing a widespread light to at times moderate rain to most areas south of Lake Ontario by midday or so, lasting through the afternoon. Drier air will try to hang on across the North Country (KART), with just the chance for a few showers later in the day. Otherwise, expect IFR/LIFR CIGS across the Southern Tier through the day on Wednesday. Further north, VFR to low VFR CIGS should hang on through at least mid morning Wednesday, before deteriorating to MVFR from late morning on across areas south of Lake Ontario. North Country will remain on the cusp of higher-end MVFR to low VFR CIGS through the afternoon. As increasing low level moisture continues to make inroads further north, some IFR CIGS will be possible from the Finger Lakes westward toward the tail end of the TAF period. An isolated rumble of thunder cannot be ruled out across the Southern Tier Wednesday afternoon as some limited instability may develop.

Outlook...

Wednesday night...IFR to LIFR with periods of rain. A low chance of a thunderstorm across the Southern Tier early.

Thursday through Saturday.. MVFR to IFR with showers.

Sunday...Mainly VFR. A slight chance of a shower or thunderstorm.

MARINE
A low pressure system moving into the eastern Great Lakes from the Ohio Valley late tonight and Wednesday will ever so slowly wobble eastward through Friday. This will cause east winds to slowly strengthen through tonight, and even moreso on Wednesday. The highest wave action will stay mainly offshore through Wednesday night, though Small Craft Advisory conditions could be reached for a period along the western shoreline of Lake Ontario by Wednesday afternoon.

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