487 FXUS61 KBUF 232033 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 333 PM EST Mon Jan 23 2023 .SYNOPSIS... Low pressure deepening toward the Canadian Maritimes will be followed by weak sfc ridge this evening with mainly quiet weather. Late tonight snow showers will redevelop northeast of the lakes, settling east of the lakes on Tuesday with the most snow occurring on the Tug Hill. Another low pressure system will bring a wintry mix and accumulating snow Wednesday into Thursday. && .NEAR TERM /THROUGH TUESDAY/... ...Winter Weather Advisory issued for brief bout of lake effect snow on the Tug Hill... Deepening low moves from the Gulf of Maine to the Canadian Maritimes this evening while a ridge of high pressure builds across from the Ohio Valley. A few lingering flurries will give way to mostly cloudy skies this evening, but overall it will be quiet with steady temperatures in the mid 20s inland to lower 30s lower elevations. Later tonight, approach of a sharp shortwave trough and low pressure trough tied to it will bring an increase of widespread lift and moisture and help lift EQLs to around 5kft. SW flow in the low- levels will help increase lake effect northeast of Lake Erie and Lake Ontario after midnight. Better chance of the lake convective layer extending into the DGZ will not be until after daybreak Tuesday, but could still be a coating to an inch of snow late tonight closer to the lakes, with an inch or two on the Tug Hill. In addition, low-level jet of 40 kts in lowest 2-3kft will result in quick ramp up of winds/gusts. Later tonight especially northeast of the lakes, expect winds around 25 mph with gusts of 30-40 mph. Once the snow starts to develop these breezy winds could result in some blowing snow. Temps late tonight will be similar to readings this evening. On Tuesday, expect fairly widespread light snow in the morning across much of the area owing to moisture and lift from the shortwave trough and sfc trough moving through. Eventually as deeper moisture exits, lake enhanced snow will take focus as winds veer westerly with inversions 4-5kft and temps as low as -10c at top of inversion. Greatest snow amounts on Tuesday will be atop the Tug Hill with convergent westerly flow and upslope lift. Generally an additional 3-5 inches will occur there during the day. To the east of Lake Erie, another 1 to 3 inches is expected, especially across higher terrain from Chautauqua Ridge across Southern Erie and into Wyoming county. Though expect the lake effect to persist most of the day, it will begin to wane later in the afternoon with arrival of high pressure ridge and weak shortwave ridging. Canadian is a bit more aggressive with upstream LES and resulting connections, keeping the LES going a bit longer. At this point, it is the only model so emphatic with that idea. Breezy winds that develop later tonight will only slowly ease on Tuesday, so could still be patchy blowing snow in the morning, especially where lake snows are most widespread. Yet another mostly cloudy day otherwise with afternoon temps mainly in the lower to middle 30s. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... ...Middle of the Week Storm to Bring Messy Weather... Heading into Tuesday night, ever so subtle ridging and associated dry air will briefly diminish lingering lake enhanced snows from earlier in the day. This being said, snow showers will be light with just nuisance accumulations southeast of both lakes. Meanwhile, across the south-central portions of the United States strong cyclogenesis will be well underway. A large closed low moving eastward across the Mexican border tonight will open up over southern Texas Tuesday. This will then spark a weakly organized surface low to develop over the lower Mississippi Valley. Then, throughout the night on Tuesday a 130-140 knot jet at 250mb will emerge out of the now negatively tilted longwave trough, supporting the surface low and lows aloft to vertically align by dawn of Wednesday over the junction point of the Mississippi and Ohio Rivers. Now what does this mean for western and north central New York? Well, in a short answer nothing pretty. In fact, with the system becoming vertically stacked (or reaching its full maturity) before moving out of the lower Ohio Valley, little to no further intensification would occur and hint at an abundance of warm air to wrap into the cyclone, thus indicating complicated scenario regarding precipitation type. This being said, through out the day on Wednesday, an unchanging surface low will push northeast across Ohio, shoving an axis of deep moisture across the forecast area. Additionally, a pronounced nose of warm air and tightening thermal gradient within the 925mb-700mb layer ahead of a 50 know low-level jet will push into the western counties of New York, resulting in a dynamic area of frontogenetic forcing and consequently a burst of moderate to heavy snow to fall over the western counties during the mid-day and afternoon hours. However, as the aforementioned warm air spills in across the region, the dendritic growth zone will essentially disappear, causing a quick changeover to rain. Due to the quick south to north changeover, daytime snowfall accumulations will range from a couple of inches across the Southern Tier to up to 4 inches across the south shore of Lake Ontario. Now regarding the eastern Lake Ontario region, the deeper cold air at the onset of this event will keep precipitation mainly in the form of snow for a longer duration, and with that being noted accumulations of 3 to 5 inches will be possible. Setting the stage for Wednesday night, a secondary jet maximum (150 knots at 250mb) will be ejected out of the base of the longwave trough across the Gulf States and advance northeastward towards the Mid-Atlantic coast. This will result in the development of a secondary cyclone to develop near the East Coast and thereby support a Miller-B cyclogenetic event. Overall this will mean that the initial parent storm now over the lower Great Lakes will weaken and transfer some of its energy to the coastal low over New Jersey, and result in a shift of the strong low-level jet and associated surge of warm air off the coast. However, this doesn't mean that this warm air won't have time to wreak some havoc across the North Country, meaning precipitation will briefly change to a mix of rain, sleet and possibly some freezing rain. It is during this timeframe where the forecast confidence is lower, since a faster transition of energy to the coast could mean that less warm air will make it across the North Country and indicate pure snow rather than a mix. Meanwhile to the west across western New York, the removal of frontogenetic forcing will result in a weak surface level convergence within a surface trough and support light mixed precipitation with insignificant percipition amounts as much of the mid-level moisture will be stripped away from the area. Overall this means, up to an inch of snow possible across the western counties, whereas east of Lake Ontario may see another 2 to 4 inches. Remnants of the upper level support for the storm system will exit across New England, while the newly formed and intensifying secondary low pushes across the Canadian Maritimes Thursday and Thursday night. A combination of cold advection and wrap around moisture in northwest flow will support widespread snow across the region. Despite the general weak synoptic lift, a couple of more inches of snow can be anticipated with higher amounts occurring across the higher terrain southeast of both lakes due to lake enhancement. Snowfall amounts Thursday will range from 1 to 3 inches with locally higher amounts across the higher terrain. && .LONG TERM /FRIDAY THROUGH MONDAY/... Heading into Friday, brief low and surface level ridging will advect in drier air across the area shifting winds from the northwest to the southwest. Overall this will diminish and shift lingering lake effect snows from southeast of the Lakes to northeast of the Lakes. Then Friday night into Saturday, a mid-level shortwave trough will support a cyclone to push across Ontario and drag its associated cold front towards the area. The cold front will stall to the west of the area Saturday, through keep the cold air across the area. Overall, the shortwave trough's axis will pass across the area Saturday and support lake enhanced snows east of both lakes. Yet another shortwave trough sliding south across the Great Lakes Sunday, will help spawn a surface low to form on the cold front lying across the area and overall support chances for precipitation through the end of the weekend and start of the new work week. && .AVIATION /21Z MONDAY THROUGH SATURDAY/... High pressure building south of the region will bring improving conditions to MVFR. Pockets of IFR will remain across the higher terrain areas. Light snow or flurries may persist a bit longer southeast of both lakes including at KROC and KJHW. Mainly MVFR expected for much of tonight, with IFR across the higher terrain of the Southern Tier and east of Lake Ontario. A weak cold front will allow light snow showers to redevelop northeast of both lakes late tonight. These snow showers look to impact KBUF, KART, and possibly KIAG after midnight and continuing into the morning hours on Tuesday. Though snow will not be as persistent, it could also occur at least briefly around daybreak at KROC and KJHW. IFR conditions are expected where snow is most persistent. Snow showers settle to east of the lakes later Tuesday morning into Tuesday afternoon while becoming scattered. Conditions will improve, but will remain mainly MVFR. Other issue tonight into Tuesday will be southwest winds that are expected to become breezy overnight into Tuesday morning with gusts over 30kts, especially to the northeast of Lake Erie at KIAG and KBUF. Outlook... Tuesday...IFR with snow showers likely toward the Tug Hill. VFR/MVFR elsewhere with a chance of snow showers. Wednesday...MVFR/IFR with snow developing, possibly mixing with rain late. Thursday into Friday...MVFR/IFR. Snow on Thursday, diminishing to snow showers east/southeast of the lakes by Friday. Saturday...MVFR/IFR with snow showers east of the lakes. VFR/MVFR elsewhere with a chance of snow showers. && .MARINE... A low pressure system off the New England coast will deepen as it tracks to the Canadian Maritimes into tonight, resulting in increasing northwest winds across both lakes. The winds will increase further later tonight through Tuesday while turning to the southwest. Small Craft Advisories remain in effect as outlined below. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Weather Advisory from midnight tonight to 7 PM EST Tuesday for NYZ006>008. MARINE...Small Craft Advisory from 7 PM this evening to 7 PM EST Tuesday for LEZ020. Small Craft Advisory until 7 PM EST Tuesday for LEZ040-041. Small Craft Advisory until 4 PM EST Tuesday for LOZ042. Small Craft Advisory until 1 AM EST Wednesday for LOZ043>045. && $$ SYNOPSIS...JLA/PP NEAR TERM...JLA SHORT TERM...EAJ LONG TERM...EAJ AVIATION...JLA MARINE...JLA