Marine Forecasts

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7 Day Forecast for Marine Location Near Lyons, NY

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Area Discussion for - Buffalo, NY

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FXUS61 KBUF 181929 AFDBUF

Area Forecast Discussion National Weather Service Buffalo NY 329 PM EDT Sun Apr 18 2021

SYNOPSIS. Scattered shower activity this afternoon will diminish by this evening as weak high pressure brings mainly dry weather through Monday. A few passing weak disturbances aloft may produce a few light, isolated showers at times. Temperatures will continue to slowly warm through Monday. More significant weather, including the possibility for some wintry precipitation, will then return by midweek as a cold front and low pressure cross the region. Unseasonably cold air will move back into our area for the second half of this week behind this system.

NEAR TERM /THROUGH MONDAY/. Mid level ridge and weak surface high continues to expand into the eastern Lake Ontario region this afternoon. However, diurnal heating and relatively cool temperatures aloft have allowed scattered showers to form over inland locations away from the immediate lake shadow southeast of Lake Ontario. Showers also developing inland over Canada will move across the Niagara Peninsula and may impact Western NY later this afternoon. Otherwise, subsidence beneath the mid level ridge should generally keep shower activity light. Temperatures will continue their slow recovery, with highs in the mid to upper 50s in most areas, cooler along the Lake Erie and Lake Ontario shore.

A weakening mid level shortwave will move northeast out of the Ohio Valley into Pennsylvania. Weak forcing and just enough available moisture may be enough to spark off a few scattered showers across northern PA, with possibly a stray shower getting into far inland portions of the western Southern Tier toward the NY/PA line. Low temperatures tonight will range from the mid 30s to the lower 40s.

Warm air advection ahead of a front dropping into the northern Great Lakes will aid in boosting temperatures Monday into the upper 50s to mid 60s, likely making it the warmest day of the week. Weak shortwave crossing the area could touch off a few afternoon showers, but otherwise expecting Monday to remain mostly dry.

SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/. A sharp mid level trough and associated surface low will move from the upper Great Lakes Monday night to Quebec Tuesday, with a trailing cold front crossing the eastern Great Lakes. Cooler air will filter into our region late Monday night and Tuesday behind the cold front. The stronger synoptic scale forcing will pass well north of the area, with forcing and moisture along the trailing cold front diminishing with time and southeastern extent. The front may produce a few light showers Monday night through the first half of Tuesday, with the greatest chance close to the Canadian border and the lowest chance near the PA state line. Most of the showers should end Tuesday afternoon as the front lays out parallel to the mid level flow.

Our attention then turns to another strong mid level trough, digging into the Upper Midwest Tuesday night before reaching the Ohio Valley and eastern Great Lakes later Wednesday. A strong baroclinic wave will develop along the frontal zone in response to increasing forcing and flow adjustments downstream of the mid level trough, with the resulting surface low running down the boundary from the Ohio Valley Tuesday night to eastern NY by Wednesday afternoon. Strong frontogenesis and differential temperature advection on the cold side of the surface boundary will support widespread precipitation later Tuesday night through the first half of Wednesday over the eastern Great Lakes.

While the large scale pattern is well agreed upon, the precise details of frontal position and low track will be critical in terms of the surface temperatures, thermal profiles, and snow potential. Model guidance has shown a good deal of run to run changes on these details, not atypical for an event still 3 days out. A swath of accumulating snow will almost certainly occur to the northwest of the low track, but model guidance has varied on placement of this from over western and north central NY to north of Lake Ontario mainly on the Canadian side of the border. There may be a narrow ribbon of sleet and freezing rain as well in the transition zone between rain and snow.

For this cycle, trended the forecast quite a bit colder for later Tuesday night and Wednesday with a rain/snow mix through that time frame, especially in areas close to the Canadian border. The current forecast represents a solution a little farther north and warmer than the 12Z GFS/ECMWF/GEM to blend in some previous, farther north model runs. It should also be noted that past history shows this type of system has a propensity to track farther north and west than model guidance would suggest several days out. The range of potential outcomes runs from very little snow at all to accumulating, impactful snow for late Tuesday night and Wednesday. Stay Tuned.

Wednesday night cold air will pour into the eastern Great Lakes behind this system, with wrap around scattered snow showers areawide. The airmass will grow cold enough for lake effect snow showers southeast of Lakes Erie and Ontario later Wednesday night.

LONG TERM /THURSDAY THROUGH SUNDAY/. As the surface low departs northeast out of the area, another shortwave will pass through the now upper level closed low, which will interact with the leftover wrap around moisture Thursday to continue to support the lake enhanced showers snow showers in the early morning before switching to all rain due to the addition of sun for places across the Finger Lakes region and to its east. While a much colder air mass overhead would typically support colder temperatures (to the tune of near freezing), thanks to the higher sun angle this time of year high temperatures will warm up into the low to mid 40s.

Upper level ridging late Thursday night through Friday night will promote mainly dry conditions. Looking into the weekend, a shortwave attached to the next incoming upper level trough may roll through supporting a frontal boundary to approach and eventually cross the area sometime Saturday or Sunday. However, this far out the model guidance is in disagreement with timing of the feature with both the ECMWF and the Canadian guidances slower to bring the boundary through. Therefore, have chances for rain showers Saturday through Sunday. Otherwise, upper level ridging will help advect warm air back into the region, rebounding temperatures into the 50s for the end of the work week and weekend.

AVIATION /20Z SUNDAY THROUGH FRIDAY/. Mainly VFR conditions as mid-level deck of diurnal cumulus continues to develop across much of the area through this afternoon. Radar imagery indicating scattered showers across the area away from the lake shadow southeast of Lake Ontario. Shower activity looks to be a greater concern for far western terminals this afternoon, particularly KIAG and KBUF. CIGS may briefly lower to MVFR in any passing showers. Quieter conditions with continued VFR conditions expected moving into this evening, with a passing mid-level deck from time to time.

Outlook .

Monday . Mainly VFR. Tuesday . MVFR to VFR with a chance of showers. Tuesday Night and Wednesday . IFR/MVFR with rain showers becoming likely. Thursday . MVFR/IFR with scattered snow showers and some lake effect snow showers east of the lakes. Windy.

MARINE. Southwest winds around 10 knots on Lake Erie and 10-15 knots on Lake Ontario will continue to produce some light to moderate chop today. In any case though, winds and waves will remain below Small Craft Advisory criteria. Winds will then diminish tonight, with generally light southwest winds on Monday, freshening a bit Monday afternoon on Lake Erie and western Lake Ontario.

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



SYNOPSIS . PP NEAR TERM . PP SHORT TERM . Hitchcock LONG TERM . EAJ AVIATION . PP MARINE . JM/PP

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
RPRN6 - Rochester, NY	35 mi	53 min	NNW 15 G 17	49°F			1011.2 hPa (-0.3)
RCRN6 - 9052058 - Rochester, NY	36 mi	53 min		51°F
OSGN6 - 9052030 - Oswego, NY	38 mi	53 min	W 14 G 18	47°F			1009.9 hPa (-0.8)	36°F

Wind History for Oswego, NY

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Penn Yan, Penn Yan Airport, NY	28 mi	60 min	NW 10 G 15	10.00 mi	Overcast	55°F	36°F	49%	1010.4 hPa

Link to 5 minute data for KPEO

Wind History from PEO (wind in knots)

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