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SLZ022 Saint Lawrence River From Cape Vincent To Saint Regis 353 Am Est Mon Dec 11 2023
Today..Northwest winds 5 to 15 knots becoming west. Rain and snow showers early, then snow showers. A chance of snow showers late.
Tonight..West winds 5 to 15 knots becoming southwest. Mostly cloudy early, then becoming partly cloudy.
Tuesday..Southwest winds 15 to 25 knots. A chance of snow showers in the morning, then a chance of rain showers in the afternoon.
Tuesday night..Southwest winds 15 to 20 knots becoming west 10 to 15 knots. A chance of snow and rain showers in the evening, then a chance of snow showers overnight.
Wednesday..West winds 5 to 15 knots. Partly to mostly cloudy.
Thursday..Southwest winds 10 to 15 knots. Partly cloudy.
Friday..Southwest winds 15 to 20 knots becoming west and diminishing to 5 to 10 knots. Partly cloudy, then becoming mostly cloudy.

SLZ005
No data

FXUS61 KBUF 111138 AFDBUF

Area Forecast Discussion National Weather Service Buffalo NY 638 AM EST Mon Dec 11 2023

SYNOPSIS
A storm system will bring rain changing to a general snow this early morning across the Eastern Lake Ontario region, while light lake effect snow falls southeast of the Lakes. The general snow will end east of Lake Ontario through the evening hours of today, however the lake effect snow will continue, accumulating southeast of the Lakes this evening, and then weaken as it lifts northward late tonight. It will be dry, but breezy Tuesday, with temperatures crossing the 40F mark for many locations.

NEAR TERM /THROUGH TONIGHT/
This morning a wave of low pressure is riding northward along an eastcoast frontal boundary. This wave off the coastline of Maine will carry northeastward through the day. To the northwest of the low, a surface trough extends northwestward back across the North Country.

General snow...Regional radars display the back edge of the general snow now exiting Lewis County. A few lighter rain shower and higher elevation snow is drifting across the North Country.
Area webcameras and surface observations display mainly snow on the higher elevations east of Lake Ontario, while lower elevations remain a mix of rain and snow. As the mid level trough axis passes across the region today precipitation will become all snow with the deepening cold air, however at this time the better lift will be exiting to our east, with just upslope flow lingering snow east of Lake Ontario through the afternoon. A winter weather advisory will remain in place here.

Lake Effect Snow...Meanwhile the colder air is generating a weak lake effect response. This activity, becoming all snow will be minor through the daylight hours downwind of the eastern Great Lakes on a west to northwest flow of shallow moisture. There may be a brief uptick and organization after sunset tonight in the lake effect snow band. Surface high pressure will press towards our region tonight, backing the surface winds while also supplying additional dryness in the lower and mid levels. This will weaken the lake bands as they lift northward, with increased wind shear late tonight all but ending any lingering lake bands of snow. An inch or two of snow southeast of the Lakes with perhaps a half inch of snow near Buffalo and Watertown as the lake snows lift northward and weaken tonight. Any snow in Buffalo would like all fall just after midnight and before the morning commute tomorrow, though east of Lake Ontario some snow may still be falling near Watertown as the morning commute commences.

Winds...West-northwest winds will increase to 15 to 25 mph with gusts up to 35 mph today. The higher gusts will be along the southern shore and inland of Lake Ontario through the afternoon hours.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
Tuesday will be a windy day, especially across the Niagara Frontier.
925mb winds increase to 40 kts and become well aligned with surface winds across the Niagara Frontier mid-day Tuesday. This combined with clearing skies suggests fairly good mixing, supporting the potential for wind gusts approaching 50 mph possible. Not as windy elsewhere where winds aloft will be weaker, but gusts 35 to 40 mph are possible. Otherwise it will be a warmer day with highs in the upper 30s to lower 40s. Some lingering lake enhanced snow showers possible east of Lake Ontario Tuesday morning.

After this, our attention turns to the potential for lake effect snow east of Lake Ontario. A short but favorable window for lake effect snow opens up Tuesday night and Wednesday. A mid-level trough will dig across New England, providing deeper moisture and dropping 850mb temps to -13C across Lake Ontario. Southwesterly flow will gradually shift to the northwest, with the westerly winds during this transition having the best chance to produce heavy snow due to the long fetch and the potential for a Georgian Bay connection. As is typical, the RGEM is by far most aggressive with this, and likely has the best handle on band location. However other high res model guidance has MUCH less QPF. Forecast will weight the RGEM, but with virtually no support from other guidance do not have the confidence to issue a watch at this time. However, this does appear likely to produce advisory snows of 4 to 7 inches on the Tug Hill with a small chance of localized warning amounts if the RGEM fully verifies.
Shorter fetch and the lack of an upstream connection will limit accumulations off of Lake Erie. Outside of this, there will be scattered snow showers Tuesday night/Wednesday, but little if any accumulation outside of the lake effect areas. Wednesday will be a fairly blustery day with highs in the lower 30s and winds gusting to 30 mph.

Winds will be northwest by late Wednesday, leading to more disorganized lake effect snows southeast of Lake Ontario. This could result in 1 to 3 inches of snow from Monroe to Cayuga counties until winds diminish and temps aloft warm by late Wednesday night.
Diminishing winds will allow for limited radiational cooling with lows ranging from the teens east of Lake Ontario to the lower to mid 20s elsewhere.

LONG TERM /THURSDAY THROUGH SUNDAY/
The long term period will feature mainly dry weather with temperatures averaging above normal. High pressure centered across the Appalachians will maintain mostly sunny skies and breezy southwesterly winds for Thursday and Friday. A moisture starved mid- level trough will track to our north across eastern Canada Friday night through Saturday night. This will bring a very small chance of rain/snow showers east of Lake Ontario, but otherwise the dry weather pattern will hold through the weekend. Thursday will be cooler with highs in the 30s, but after that highs will be in the 40s through the weekend.

AVIATION /11Z MONDAY THROUGH FRIDAY/
For the 12Z TAFS widespread precipitation is exiting to the east, with now scattered activity...becoming lake effect through the day as cold air deepens following the passage of a mid level shortwave trough. Flight conditions will generally be VFR to MVFR.

This evening bands of lake effect snow will still be ongoing to the southeast of the Lakes. These bands will reach KJHW off Lake Erie, while the KROC airfield may be brushed by snow from time to time. Winds will back later tonight, and the addition of drier air and less favorable lake effect parameters will weaken the bands of snow as they lift towards KBUF around 06Z, and KART around 09Z. Outside of the lake snows tonight it will be VFR flight conditions.

Winds will become gusty today, with west to northwest winds gusting upwards to 30 knots. Strongest gusts will likely be along and inland from the southern Lake Ontario shoreline including the KROC airfield.

Outlook...

Tuesday...Mainly VFR. Breezy.

Tuesday night through Wednesday...Areas of MVFR/local IFR with lake effect snow showers, mainly east of Lake Ontario.

Thursday and Friday...VFR.

MARINE
Westerly winds will increase Monday, producing higher end Small Craft Advisory conditions on Lake Erie and Lake Ontario. The winds will increase again on Tuesday ahead of a cold front, with southwest winds 30 knots on both Lake Erie and Ontario through the day.
Thereafter west to northwest winds will continue small craft advisory conditions through most of the week.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Winter Weather Advisory until 7 PM EST this evening for NYZ006>008.
MARINE...Small Craft Advisory until 1 AM EST Thursday for LEZ040-041.
Small Craft Advisory until 1 AM EST Thursday for LOZ042.
Small Craft Advisory until 1 AM EST Tuesday for LOZ030.
Small Craft Advisory until 7 AM EST Thursday for LOZ043>045.

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