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SLZ022 Saint Lawrence River From Cape Vincent To Saint Regis 338 Am Est Sun Dec 10 2023
Today..South winds 5 to 15 knots becoming southwest. Rain showers likely early, then rain late this morning. Rain showers likely this afternoon.
Tonight..Southwest winds less than 10 knots. Rain showers likely early, then snow and rain showers likely late in the evening. Snow after midnight.
Monday..Northwest winds 10 knots or less increasing to 10 to 15 knots. Snow in the morning, then a chance of snow showers in the afternoon.
Monday night..West winds 5 to 15 knots becoming southwest. Partly to mostly cloudy.
Tuesday..Southwest winds 15 to 25 knots diminishing to 10 to 15 knots. A chance of snow showers during the day, then a chance of snow and rain showers Tuesday night.
Wednesday..West winds 5 to 15 knots. A chance of snow showers during the day.
Thursday..Southwest winds 5 to 15 knots increasing to 15 to 20 knots. Partly cloudy.

SLZ005
No data

FXUS61 KBUF 101451 AFDBUF

Area Forecast Discussion National Weather Service Buffalo NY 951 AM EST Sun Dec 10 2023

SYNOPSIS
A cold front will ease its way across the region today with a period of rain showers across western NY and a soaking rainfall across north central NY. A transition to snow is expected as colder air deepens across the region through the evening hours. Accumulating snow is likely across higher terrain, and especially the Tug Hill and western foothills of the Adirondack mountains. Lighter snow accumulations across lower elevations through Monday morning with all areas dropping to or below the freezing mark.

NEAR TERM /THROUGH MONDAY/
A cold front extends from the eastern shore of Lake Ontario to the Finger Lakes region this morning. The front will move through the eastern Lake Ontario region by noon. Regional radar shows rain showers just west of the front with the backedge through Buffalo. Mild this morning with temperatures in the 40s across the region. Temperatures will be slowly falling through the afternoon.

Another wave of moderate rain arrives from the southwest later this morning especially across the Finger Lakes and east of Lake Ontario as an approaching southern stream wave and right entrance region of a 110 knot 300 hPa jet combine forces. Instability is weakening, and thunder chances will become negligible.

Additional rainfall today will range from two-thirds of an inch on the upslope southern Tug Hill, while back towards the west a tenth of an inch or less will be common for areas west of Rochester- Batavia-Jamestown.

The upper level trough axis will approach our region tonight. This will funnel a colder airmass into our region, while lift ahead of the feature, and surface wave along the frontal boundary just to our east will aid in precipitation expanding westward some into our region. Rain will change to snow, mainly in the 00Z to 06Z timeframe, with another shortwave approaching our region from the south enhancing precipitation and snowfall rates across the eastern Lake Ontario region tonight. Here, and especially on the Tug Hill and western foothills of the Adirondack Mountains will snowfall rates approach an inch per hour at times after midnight and through dawn Monday morning. This shortwave will pass quickly Monday morning with snowfall rates/snow beginning to taper down, and becoming more focused on the upslope areas east of both lakes on a west to northwest wind.

Farther to the west and away from the deeper moisture and lift snow will be lighter, with an inch or two on the Hills, and less than an inch at lower elevations. However, by Monday morning temperatures will be lowering to around the freezing mark or lower, thus any untreated wet roads may produce slippery spots, especially bridges and overpasses.

As cold air deepens attention will shift from the synoptic snows to lake effect snows. Through the day Monday temperatures at 850 hPa will lower to around -10C. Flow of west to northwest will likely develop a broad band of lake snows focused upon the Chautauqua Ridge as well as areas southeast of Lake Ontario. Winds will be backing through the later afternoon hours, lifting bands of snow back northward, which will keep overall snow totals in the lake bands down. Could possibly see advisory amounts on the Chautauqua Ridge.

As far as the eastern Lake Ontario region have elected to convert the watch to a high end winter weather advisory. Will keep the time the same, though expecting the bulk of the synoptic snows through midday Monday. Feel the axis of deeper moisture/snow from a model consensus will be just to our east which will keep snow amounts from pushing into warning criteria.

It will also be a blustery day Monday with west to northwest winds gusting to 35 mph. The wet nature of the snow should limit blowing and drifting snow. These winds will create apparent temperatures in the teens to lower 20s, a big contrast from this prior mild weekend.

SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
Strong low pressure will exit into the Canadian Maritimes Monday night, but a mid level trough trailing the system will linger across New England. 850mb temps will start the evening around -11C across Lake Ontario, and this combined with some moisture from the departing trough will leave a narrow window for a lake effect snow band to lift northward as winds shift from northwest to southwest.
Could see an additional 1-3 inches of snow on the western side of the Tug Hill. Warmer air aloft and less synoptic moisture will limit snow off Lake Erie, with any accumulation less than an inch.
Otherwise it will be seasonably cool and a bit windy with lows in the 20s.

A few lingering snow showers are possible in Jefferson County Tuesday morning, but otherwise high pressure across the mid-Atlantic will ridge towards our region promoting fair weather and a clearing trend for Tuesday. The pressure gradient between the surface high and an approaching cold front will result in a breezy day with wind gusts to 40 mph across the Niagara Frontier and to 30 mph inland.

A trough will dig across eastern Canada Tuesday night and Wednesday, with an associated cold front moving across Western NY. Modest synoptic moisture with the trough and 850mb temps dropping to around -13C will support a limited lake response. There's some model disagreement how cold aloft it will get (the GGEM is much colder than the GFS). Model consensus suggests there will likely be accumulating snows east of Lake Ontario with a potential for 3-5 inches. It'll be warmer aloft over Lake Erie, with less moisture so any snow accumulations will be minimal. The cold front will only drop temperatures to near or slightly below normal with highs in the 30s on Wednesday.

LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/
There will be some lingering lake effect snow showers east and southeast of Lake Ontario Wednesday night. After this, surface high pressure centered near West Virginia will ridge towards our region Thursday and Friday. This pattern provides forecast confidence in a dry weather pattern for Thursday and Friday. A weak trough may bring a small chance for rain or snows showers Saturday. Temperatures will average above normal during the period, with the warmest day on Friday when highs will climb well into the 40s.

AVIATION /15Z SUNDAY THROUGH THURSDAY/
For the 12Z TAFS a cold front crossing the Finger Lakes region will continue to send numerous showers across the TAF region this morning with flight conditions largely MVFR and higher elevation IFR. Within breaks in shower activity there may be low end VFR ceiling heights.

Precipitation activity will be most numerous today across eastern zones (KART) while there may be a period of dry weather and return to low end VFR ceiling heights towards the west. As the upper level trough passes across the region tonight, precipitation will expand westward, and within deepening cold air change to snow. For most sites this will occur between the hours of 00 and 06Z. By late tonight much of the falling precipitation will be in the form of snow. This snow is likely for KART with IFR visibilities, while KROC and KJHW may also have a period of IFR in snow. Snow for KIAG and KBUF will be brief.

Outlook...

Monday...MVFR. Breezy with a chance of snow showers. IFR and likely snow east and southeast of Lakes Erie and Ontario.

Tuesday through Thursday...Mainly VFR.

MARINE
Cold front continues to slice across Lake Ontario this morning.
Westerly winds behind the front will initially focus the stronger gusts and wave heights on the eastern ends of the Lakes, but as the winds veer to northwesterly higher waves on Lake Ontario will reach the nearshore waters of central and southeastern Lake Ontario.

We will have a brief lull in winds and lowering waves this evening.
This will bring a brief period of sub-SCA conditions. However a deepening cold airmass behind an upper level trough will bring back gusty winds that could continue SCA on both lakes deep into this week.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Winter Weather Advisory from 7 PM this evening to 7 PM EST Monday for NYZ006>008.
MARINE...Small Craft Advisory until 10 PM EST this evening for LEZ040- 041.
Small Craft Advisory until 10 PM EST this evening for LOZ045.
Small Craft Advisory until 10 PM EST this evening for LOZ043-044.

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