Marine Weather and Tide Forecast for Clayton, NY

KEY MESSAGES
1.) Isolated showers and thunderstorms today will be followed by dry weather tonight through Tuesday.

2.) Another round of isolated to scattered showers and thunderstorms is forecast for the midweek period.

DISCUSSION
Key Message 1...Isolated showers and thunderstorms today will be followed by dry weather tonight through Tuesday.

Cyclonic W'erly flow aloft and embedded shortwave troughs impact Western and Central NY through this early evening. At the surface, a cold front was located just east of Barrie, ON, just west of Hamilton, ON, and extended generally S'ward across central Lake Erie at 2:20 AM EDT this morning. This front should sweep E'ward across our CWA between about 3 AM and 1 PM EDT today. Ahead of and behind the front, subtle surface trough axes attendant to the shortwave troughs aloft will traverse Western and Central NY generally from west to east. In addition, behind the front, a surface ridge will build slowly from the Upper Midwest and vicinity. Isolated and periodic showers and thunderstorms are expected through this early evening as low-level convergence and moist ascent along the cold front and surface trough axes release weak boundary layer CAPE. However, the threat for these showers and storms should end gradually and generally from west to east late this morning through early evening as the building surface ridge is accompanied by a lowering, strengthening, and stabilizing subsidence inversion.
Lows should reach the 60's around daybreak this morning. Highs should reach the 70's to lower 80's late this afternoon, behind the weak cold front and amidst partly to mostly cloudy sky.

The high pressure ridge at the surface and aloft will build from the western Great Lakes and vicinity tonight through Tuesday. Stabilizing subsidence accompanying the ridge is expected to promote dry weather. Considerable clearing and weak or calm surface winds accompanying the ridge should contribute to lows reaching the 50's to lower 60's around daybreak Tuesday.
Steam fog should form in the river and lake valleys of the Western Southern Tier, Finger Lakes, and Eastern Lake Ontario Region late this evening and especially during the predawn hours of Tuesday morning. Patchy radiation fog should also form during the same time period, especially inland from Lakes Erie and Ontario, amidst lingering low-level moisture from recent rainfall. Fog will dissipate via the onset of diurnal convective mixing of the boundary layer shortly after daybreak. Highs are forecast to reach the 70's to lower 80's late Tuesday afternoon.

Key Message 2...Another round of isolated to scattered showers and thunderstorms is forecast for the midweek period.

The above-mentioned ridge at the surface and aloft exits E'ward Tuesday night and allows a warm front to sweep N'ward through Western and Central NY. Simultaneously, cyclonic W'erly flow aloft becomes established over our area and embedded shortwave disturbances traverse Western and Central NY. The cyclonic W'erly flow aloft and embedded shortwave disturbances should continue to affect our area on Wednesday, when a cold front should sweep SE'ward through Western and Central NY. Isolated to scattered showers and thunderstorms are expected after midnight Tuesday night through Wednesday as weak to perhaps moderate CAPE, included elevated CAPE, is released by the following: moist isentropic ascent along the upper-reaches of the warm front and ahead of shortwave trough axes; low-level convergence and moist ascent along the surface warm front, surface cold front, and surface trough axes attendant to the shortwave troughs. Overnight lows should reach mainly the mid 50's to mid 60's Tuesday night and be followed by daytime highs in the 70's to 80F on Wednesday.

During Wednesday night through Thursday, a ridge at the surface and aloft is expected to build from the western Great Lakes and vicinity. Primarily fair weather is expected in Western and Central NY as stabilizing subsidence accompanies the ridge.
However, a few rain showers associated with moist isentropic ascent along the upper-reaches of the departing cold front may impact the Western Southern Tier and southern Finger Lakes Wednesday evening. Latest trends in NWP model guidance suggest the cooler air mass behind the cold front may be too dry and not cold enough to support a period of lake-effect rain. Overnight lows should reach the upper 40's to near 60F around daybreak Thursday as the cooler air mass overspreads our region behind the cold front. Highs should reach the 70's late Thursday afternoon.

AVIATION /09Z MONDAY THROUGH FRIDAY/
W'erly flow aloft and embedded disturbances affect Western and Central NY through 12Z/Tues. At the surface, a cold front was located just east of KROC and just west of KELZ at 10Z/Mon.
This front will continue moving E'ward and should exit the rest of our area by 17Z/Mon. Behind the front, a high pressure ridge builds very slowly from the Upper Midwest through ~00Z/Tues and then builds in earnest through 12Z/Tues. Our regional surface winds trend SW'erly around 5 to 10 knots ahead of the cold front and W'erly to NW'erly around 5 to 10 knots behind the front.
Surface winds are then expected to be light and variable or calm between ~00Z/Tues and 12Z/Tues. Isolated showers and thunderstorms with brief MVFR to IFR will end generally from west to east late this morning through early evening. KJHW and KART have the greatest chance to be impacted by this convection.

Widespread MVFR to IFR ceilings should rise to near 3.5kft to 5kft AGL late this morning through early evening and generally from west to east as stratocumuli evolve into diurnal cumuli.
The cumuli will then dissipate around sunset this evening and give way to mainly clear sky with a few passing cirrus accompanying the aforementioned disturbances. Weakening surface winds and lingering low-level moisture should lead to mist and fog between ~03Z/Tues and 12Z/Tues, especially inland from Lakes Erie and Ontario and along/near the lake and river valleys of the Western Southern Tier, including KJHW, Finger Lakes, and Eastern Lake Ontario Region. Conditions will vary between MVFR and LIFR in the mist/fog.

Outlook...

Tuesday...Dry weather and mainly VFR. Any lingering mist/fog is expected to dissipate by mid-morning.

Tuesday Night and Wednesday. Isolated to scattered showers and thunderstorms with MVFR or worse conditions expected.

Wednesday Night through Friday...Dry weather and mainly VFR, although localized fog in/near river/lake valleys is possible around daybreak on Thursday and Friday.

MARINE
Wind speeds around 5 to 15 knots and waves of 3 feet or less are expected through this Friday. A cold front will sweep E'ward across eastern Lake Erie and Lake Ontario this morning and cause SW'erly winds to veer to W'erly to NW'erly. Behind the front, a trough lingers over the lakes today before a high pressure ridge builds from the Upper Midwest tonight. Winds should vary between mainly W'erly and N'erly. On Tuesday, the ridge axis should move E'ward across eastern Lake Erie and Lake Ontario, and cause winds to back to SW'erly. A cold front should sweep SE'ward across eastern Lake Erie and Lake Ontario Wednesday and cause SW'erly winds to veer to NW'erly to N'erly. Behind the cold front, a ridge should build from the Upper Midwest and western Great Lakes through Friday and cause winds to become variable in direction.

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