Marine Weather and Tide Forecast for Willoughby, OH

NEAR TERM /THROUGH MONDAY NIGHT/
No major changes to the forecast at this time.

Previous Discussion...
High pressure influences from the south are short lived cross our CWA, shifting east of the region by this evening. Cold front now pushing eastward through Illinois will make it's way into western Ohio over the next few hours. Surface low well north of the region in Lake Superior and the upper level energy in the form of a trough axis/PVA is in northern Michigan. Expecting only scattered precipitation as a result further south in our forecast area where the f-gen is less organized. A look at the vertical profiles continues to show that despite some good saturation depth, it fails to consistently reach the dendritic growth zone. Snow is still going to be the most dominant precipitation type, but as time goes on, the depth of the moisture will shrink from the top down ,and at times, freezing drizzle should be expected. This will be patchy overall and do not expect an icing issue in the sensible weather, but it will still be a possibility for brief periods of time as the front comes through. In the wake of the cold front Monday, trending colder once again, and lots of single digit low temperature Monday night.

As the cold frontal precipitation exits, conditions begin to align for a lake effect setup. Thermal trough over the lake and surface convergence resulting from it sets up just offshore oriented with the shoreline around 00Z Tuesday. The trough will deepen, and the 925mb f-gen will slowly drift inland towards the 12Z Tuesday rime frame. During this time, will also see hints of 0-2km CAPE develop and increasing values of the snow squall parameter. This is primarily a short term forecast period event, but it will begin at the end of the near term period, and have started a Winter Storm Watch for the lake effect snow 06Z Tuesday.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
Cyclonic W'erly to NW'erly flow aloft and embedded shortwave troughs impact our region through about midday Wednesday. The strongest of these shortwave disturbances is still expected to sweep SE'ward through our area on Tuesday. Later Wednesday, a shortwave ridge begins to build from the western Great Lakes and vicinity. At the surface, a trough lingers over and near the Great Lakes, including our CWA, before the ridge begins to build from the western Great Lakes and Lower OH Valley by Wednesday afternoon and early evening.
This weather pattern will maintain an unusually-cold air mass across our region as 850 mb temperatures are forecast to vary between -15C and -20C over and downwind of ~1C Lake Erie, which will maintain lake-effect snow (LES) and allow a large portion of the lake-effect cloud layer to reside in the DGZ (see additional details below).
Afternoon high temperatures are expected to reach the mid teens to lower 20's on Tuesday and the upper teens to mid 20's on Wednesday.
Overnight lows are expected to reach mainly the 5F to 15F range around daybreak Wednesday morning.

LES is expected to stream generally ENE'ward over/downwind of Lake Erie at daybreak Tuesday morning. However, as the aforementioned strong shortwave trough sweeps SE'ward through our region, the mean low-level flow will veer steadily from WSW'erly to WNW'erly through sunset Tuesday evening as low-level moisture remains deep and abundant. Accordingly, an intense LES band is expected to shift S'ward into the primary snowbelt and vicinity in NE OH/NW PA and evolve into multiple snow bands due, in part to a decrease in fetch.
Periods of LES are expected to persist in/near the snowbelt Tuesday night through about midday Wednesday as mean low-level flow varies between NW'erly and W'erly. Later on Wednesday, the LES is expected to begin shifting N'ward and impact mainly portions of the primary snowbelt as mean low-level flow backs toward WSW'erly. The LES will be heavy at times as low-level convergence along the band(s) is expected to yield strong and maximized ascent in a cloudy DGZ about 1 km thick. The heaviest LES is expected Tuesday morning, when greater fetch and well-aligned low-level flow will promote greater lake-induced CAPE and higher lake-induced equilibrium levels.
Outside the LES, scattered snow showers are expected to accompany moist isentropic ascent ahead of the axis of the aforementioned shortwave trough on Tuesday and stem from low-level convergence/moist ascent along the attendant surface trough axis.
Otherwise fair weather is expected Tuesday night through Wednesday outside the LES.

During Wednesday night, the ridge at the surface and aloft will exit quickly E'ward as another trough at the surface and aloft overspreads our CWA from the Upper Midwest and vicinity. Lows are expected to reach mainly the 5F to 15F range around daybreak Thursday. Moist isentropic ascent ahead of the shortwave trough axis will allow scattered snow showers to impact our CWA, especially after midnight. The LES is expected to continue to shift N'ward and eventually offshore our CWA overnight Wednesday night as mean low- level flow backs from WSW'erly to SW'erly. LES intensity is expected to wane, overall, via a lowering subsidence inversion accompanying the aforementioned ridge and then via low-level WAA ahead of the trough axis that will follow the ridge. Snowfall totals are expected to reach 6" to 18" in the heaviest/most-persistent LES across far- northern Ashtabula County and Erie County, PA with a tight gradient in totals along/near the lakeshore. Snowfall totals are expected to average 3" to 6" elsewhere in the primary snowbelt, while lesser snow accumulations are forecast elsewhere in our CWA

LONG TERM /THURSDAY THROUGH SUNDAY/
A shortwave trough and attendant surface trough axis are expected to sweep E'ward through our region on Thursday and generate scattered snow showers via moist isentropic ascent ahead of the shortwave trough axis and low-level convergence/moist ascent along the surface trough axis. Minor snow accumulations are possible and afternoon highs are forecast to reach the mid 20's to lower 30's. Snow is expected to end from west to east Thursday evening and be followed by fair weather through Friday as stabilizing subsidence accompanies the ridge. Lows in the upper teens to mid 20's around daybreak Friday morning are expected to be followed by highs in the lower to mid 30's in the afternoon as net WAA develops along the western flank of the low-level ridge.

Cyclonic SW'erly to W'erly flow aloft and embedded shortwave disturbances are expected to impact our region Friday night through Sunday as surface troughing becomes established over the eastern Great Lakes and Upper OH Valley. A cold front is still expected to sweep E'ward through our CWA on Saturday. Periodic and scattered snow showers are expected to accompany the shortwave troughs and cold front. Rain may mix with the snow at times, especially during the daylight hours of Saturday and ahead of the cold front. Farther behind the front, sufficient CAA should allow LES showers to develop over and generally southeast of Lake Erie Saturday night through Sunday. Overnight lows should reach the mid 20's to lower 30's Friday night and be followed by daytime highs in the 30's on Saturday, ahead of the front. Overnight lows should then reach the mid teens to lower 20's Saturday night and be followed by daytime highs in the lower to mid 20's on Sunday as relatively-strong net CAA and abundant cloud cover limit daytime warming.

AVIATION /00Z Monday THROUGH Friday/
A cold front entering the region has allowed for a band of MVFR and light snow showers to enter the western airspace this evening. Clear conditions or mid-to-high level clouds are starting to get edged out by this MVFR ceiling layer and some terminals are seeing some light snow showers to start. Snow will build into the area in earnest overnight and MVFR vsby in snow will be possible and have mentioned within most TAFs. There could be some pockets of IFR with the snow, especially at the usual suspects like KMFD and KCAK. Behind the cold front, snow will move out of most of the area but the low ceilings will remain. Snow will continue in NE OH and NW PA with lake effect and mainly be a problem for KERI, where snow continues through the end of the TAF period. Winds will start southerly and veer to the west with the front. Wind gusts to 25 kt expected through the period with some 30 kt winds expected with the lake effect snow around KERI.

Outlook...Non-VFR ceilings will continue across the airspace on Monday night and Tuesday. Non-VFR in lake effect snow will continue through Wednesday across NE OH and NW PA. Non-VFR possible in ceilings and system snow across the area on Thursday.

MARINE
Based on latest forecast trends, a Small Craft Advisory has been issued for 10 PM today to 7 AM Wednesday for Vermilion to Avon Point and for 10 PM today to 7 PM EST Wednesday for Avon Point to Ripley.
Note: The issuance of Small Craft Advisories has been suspended temporarily farther west due to extensive ice cover in/near the western basin.

A ridge exits E'ward before a cold front sweeps E'ward across Lake Erie on Monday. S'erly to SW'erly winds around 10 to 20 knots this afternoon freshen to 15 to 25 knots this evening and then veer to W'erly with Monday's cold front passage. Ahead of the cold front, waves trend 3 feet or less in nearshore U.S. waters and 3 to 7 feet in open U.S. waters. Behind the front, waves as large as 3 to 6 feet, accompanied by occasional waves up to 9 feet, are expected in ice-free waters of the central and eastern basins.

Winds are expected to vary between SW'erly and NW'erly around 15 to 25 knots as a trough lingers over Lake Erie Monday night through Tuesday night. Waves as large as 4 to 9 feet are expected in the central and eastern basins. On Wednesday, SW'erly to NW'erly winds are forecast to ease to 10 to 20 knots and allow waves to subside slowly to 3 to 5 feet as a ridge moves E'ward across Lake Erie.
Behind the ridge, a trough is expected to impact Lake Erie during most of Wednesday night through Friday, but another ridge should build briefly from the Lower OH Valley Thursday night. Primarily SW'erly to W'erly winds are expected. These winds will be around 15 to 25 knots Wednesday night through Thursday before easing to around 10 to 20 knots Thursday night through Friday. Waves are expected to rebuild to around 5 to 9 feet in ice-free waters of the central and eastern basins Wednesday night through Thursday before subsiding gradually to 4 feet or less Thursday night through Friday.

CLE WATCHES/WARNINGS/ADVISORIES
OH...Winter Storm Watch from late Monday night through late Wednesday night for OHZ089.
PA...Winter Storm Watch from late Monday night through late Wednesday night for PAZ001-002.
MARINE...Small Craft Advisory from 10 PM this evening to 7 AM EST Wednesday for LEZ145.
Small Craft Advisory from 10 PM this evening to 7 PM EST Wednesday for LEZ146>149.