Marine Weather and Tide Forecast for Hamlin, NY

KEY MESSAGES
1) Widespread snow expected today and tonight as a weak low and an Arctic cold front cross the region, some of the snow may be heavy later this evening with potential squalls and along the cold front.

2)Wrap around moisture and lake effect snow will develop behind the Arctic cold front Saturday through Saturday night, with blowing and drifting of the fresh snowpack.

3) Dangerously cold wind chills between 15 and 35 below zero are expected this weekend.

DISCUSSION
KEY MESSAGE 1... Widespread snow expected today and tonight as a weak low and an Arctic cold front cross the region, some of the snow may be heavy later this evening with potential squalls and along the cold front.

A strong vertically stacked low over James Bay will send its strong Arctic cold front southeast across the Central & Eastern Great Lakes through the day today and tonight. As the cold front tracks southeast out of the the Upper Midwest and Upper Great Lakes, a strong shortwave trough and vorticity maximum will track along the western fringe of the larger parent trough. As this shortwave trough and vort max catchup to the cold front, a weak sfc low will develop over the Central Great Lakes along the front and continue southeast, tracking along/near the north shore of Lake Ontario this afternoon and into Northern NY by later this evening. The core of the Arctic airmass is associated with this stronger shortwave trough and vort max and drops temperatures aloft behind the cold front further once they phase.

Widespread light snow has started for the far western NY area, and will continue east through the afternoon. This first batch of snow will be associated with a weak mid-level warm front.
Snow this morning with this weak warm front/warm air advection will remain on the lighter side as it pushes east. Higher resolution guidance suggest a lull of a few hours in the steadier snow with a more scattered nature. Generally late morning into the mid afternoon from west to east. Snow will then increase some for a few hours after this lull as a shortwave trough/weak front crosses the area during the later portion of the afternoon for western areas and early evening for eastern portions of the area. Snow will then increase additionally, becoming at least moderate at times for a few hours as the strong Arctic cold front crosses the region, generally from around 8pm to 2am from Western NY to the North Country. Snow along the cold front and within potential squalls will have the potential to become heavy for an hour or two with drastically reduced visibilities and a quick inch or so. After the cold front crosses, snow will become lighter, but will persist through most of the first half of the night. Lake enhancement off of Lake Ontario and upsloping east of Lake Erie will increase the potential for snow to linger into the early portion of the day on Saturday. Snowfall amounts of 2 to 4 inches are expected across much of the area from today through tonight, with some higher amounts closer to 6 inches for the higher terrain near Lake Erie and for areas along the south shore of Lake Ontario.

Winds will also increase later in the afternoon and through the night as the pressure gradient over the region tightens with the incoming cold front. Winds along the cold front will gust to around 40 mph, causing blowing and drifting snow, further reducing visibilities within any areas of snowfall, and especially with the heavier snow expected with the cold front. With strong cold air advection behind the passing cold front, gusty winds to at least 35 mph will continue through the rest of the night, prolonging blowing snow conditions and reductions to visibility.

KEY MESSAGE 2...

A mid-level trough axis will move across the region Saturday. Deep moisture and large scale ascent will exit to the east with widespread snow coming to an end Saturday. A very cold, northwest flow across the eastern Great Lakes and modest low-level moisture will support lake effect snow showers downwind of of Lake Ontario through the weekend. Forecast soundings show sub-par conditions, with equilibrium levels between 3-5km and moisture continuing to retreat to the east through Sunday. Due to the very cold airmass, a fluffy couple of inches is possible in the most persistent snow Saturday through Sunday.

KEY MESSAGE 3...Dangerously cold wind chills between 15 and 35 below zero are expected this weekend.

Arctic air will arrive on the backside of a strong cold front late tonight through Saturday and cold weather will persist across the region through Sunday. A 50-knot low-level jet with 850mb temperatures around -28C will spread across the forecast area late tonight through Saturday. The core of the coldest air will slowly lift eastward across the North Country into northern New England Saturday night through Sunday. Temperatures will plummet behind the cold front from west to east late tonight through Saturday. Low temperatures will fall to near zero to the single digits below zero by sunrise Saturday. Little improvement is expected during the day with highs near zero to the single digits.

Strong winds behind the front will exacerbate this cold airmass and create wind chills well below zero. The combination of frigid temperatures and strong winds will create dangerous wind chills across the region. Wind chills as low as 30 below zero are expected to be felt across the higher terrain south of Buffalo, and across the Finger Lakes region late tonight through Saturday, then east of Lake Ontario Saturday through Sunday morning. While still very cold, wind chills will be slightly higher (15 to 24 below zero) across the Niagara Frontier and southern shore of Lake Ontario. Winds will diminish across the region later Saturday through Sunday which will allow wind chills to improve during the day, before dropping back down Saturday night. Cold weather headlines are in effect for the entire region for the weekend.

An upper level ridge will build into the Plains the start of the work week and "warmer" weather is expected to start the work week.

AVIATION /12Z FRIDAY THROUGH TUESDAY/
Conditions will transition from mainly VFR this morning to persistent periods of MVFR/IFR conditions through the morning and the rest of today with light to at times moderate snowfall pushing into the areas causing lower VSBYs and CIGs . This will occur as a weak sfc low and cold front approach the region today. Periods of LIFR conditions can't be ruled out during the day today, but should be brief, the best chance for this will be as winds increase later in the day, causing some blowing and drifting of snow.

Tonight, a weak sfc low and strong Arctic cold front will cross the region tonight. Widespread snow is expected to continue through most of the first half of the night, with periods of moderate to heavy snow at times, especially within snow squalls and with the passing Arctic cold front. Reductions in VSBY and CIGs to IFR is expected to continue through most of the night.
Within these heavier snow showers, LIFR and brief VLIFR conditions will be possible at times. Increasing winds late this afternoon and through much of the night will cause blowing and drifting snow, further reducing VSBYs outside of the moderate to heavy snowfall.

Outlook...

Saturday through Sunday... Areas of IFR in lake effect snow showers south of Lake Ontario.

Monday through Tuesday...VFR/MVFR with a chance of light snow showers.

MARINE
A strong arctic cold front will pass across the region tonight through Saturday resulting in a period Gales across the far western and central portions of Lake Ontario, and Small Craft Advisories on Lake Erie. This being said, a Gale Warning is in effect for tonight into Saturday morning for the western and central portions of Lake Ontario. Due to the frigid nature of the airmass overhead, along with the strong winds, freezing spray will also be likely on Lake Ontario. Winds and waves will subside later Sunday as surface high pressure builds into the lower Great Lakes.

Please note...Most, if not all of the Lake Erie nearshore waters are now ice covered. Waves have been omitted from the forecast.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Winter Weather Advisory until 7 PM EST Saturday for NYZ001-002- 010>012-019-020-085.
Cold Weather Advisory from 1 AM Saturday to 10 AM EST Sunday for NYZ001>005-010-011.
Winter Weather Advisory from 1 PM this afternoon to 7 AM EST Sunday for NYZ003>006-013-014.
Extreme Cold Warning from 7 AM Saturday to 1 PM EST Sunday for NYZ006>008.
Extreme Cold Warning from 1 AM Saturday to 10 AM EST Sunday for NYZ012>014-019>021-085.
MARINE...Small Craft Advisory from 7 PM this evening to 4 PM EST Saturday for LEZ040-041.
Small Craft Advisory from 7 PM this evening to 1 AM EST Sunday for LOZ030.
Gale Warning from 7 PM this evening to 10 AM EST Saturday for LOZ042-043-062-063.
Heavy Freezing Spray Warning from 7 PM this evening to 10 AM EST Saturday for LOZ042-043-062-063.