724 FXUS61 KBUF 281021 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 521 AM EST Sun Jan 28 2024 .SYNOPSIS... Low pressure passing to the south of the region today will bring rain that slowly transitioning over to snow. Higher terrain of the Southern Tier and western Finger Lakes will see the greatest accumulations, with a slushy accumulation for lower elevations. Low pressure exits out to sea tonight with widespread precipitation gradually ending diminishing from west to east. Some snow showers will be possible Monday morning but will gradually end during the afternoon. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Low pressure system moving through OH/WV which will transfer energy to a developing coastal low near the Delmarva coast today. Deep moisture being transporting northeastward and organized forcing for ascent in the right entrance region of a 120+ knot upper level jet will support widespread light to moderate precipitation across Western NY and parts Central NY today, with the possible exception of near the Saint Lawrence River. Looking like it will be too far removed from forcing and closer to a drier airmass across Quebec. As was alluded too in previous AFDs...p-type (rain vs. snow) continues to be the main challenge, and where/when it changes over to snow. Taking a look at latest Bufkit profiles, there is a bit of a later trend in the advertised change over to snow. This is 'not' much of a surprise given thermal profiles are not all that cold. We could end up with very little snow at all even for elevated locales...high bust potential (low confidence). That said...the "key" will be dynamic cooling of the column for the anticipated change over to all snow by late this morning/early this afternoon. The main focus will be the higher terrain of the Southern Tier and western Finger Lakes where Winter Weather headlines are in place. The change over to wet snow will over time progress to lower elevations through the day as the column cools, and the start of weak cold advection lowers the melting layer. The lake plains should change to mainly wet snow by this evening. Western and Central NY is then advertised to remain in the favorable location near the pivot point of the warm conveyor/TROWAL airstream supporting widespread light to moderate precipitation into this evening. Snowfall accumulations... Accumulations will be 'highly dependent' on where/when the change over to snow occurs. As was said above...there is subtle signs or a drift to a later change over. This may or will slightly 'lower' total accumulations for the entire event. However...have only made minor adjustments with this update for the moment. The highest snowfall totals still expected across the Southern Tier and western Finger Lakes (above 1700ft MSL) may see as much as 2-4", isolated higher amounts through Sunday night. This would include the ridges of Wyoming County, The high spots in Allegany and northeast Cattaraugus counties, the Brisol Hills in Ontario County, and the highest hills of southern Livingston County near Springwater and Ossian. The footprint of these greater accumulations will likely be quite small in each county, with only 1- 2" expected for lower elevations where much of the population is located. For the lower elevation (lake plains)...expect to see 1-2 inches of slushy accumulation through tonight. Roads across the lower elevations including Buffalo and Rochester will likely stay just wet through the day Sunday, but some slushy/slick spots may develop as air and pavement temperatures fall this evening and tonight. The coastal low rapidly heads out to sea with the trowel working east of the region overnight. We should see precipitation (snow) slowly wind down as we head into Monday with just some left over snow showers by Monday morning. Additional snowfall accumulation of an inch or less is then expected for most locations. A brief shot of colder air will also wrap in behind the system tonight with temps falling into the upper 20s to lower 30s. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... The low pressure system which impacted the region on Sunday will exit to the east Monday. Cold advection within a northerly flow on the backside of the low will send 850 mb temperatures to near -10C. This will be cold enough to generate a lake response mainly focused south of Lake Ontario, especially for favorable upslope areas. These snow showers will be more widespread during the morning with the potential for minor additional accumulations (<2"). Coverage of snow showers will lessen during the afternoon as drier air and subsidence associated with high pressure builds in from the west. Temperatures not improving much during the day Monday within a cold advection, with most highs in the lower to mid 30s but in the upper 20s across the higher terrain. A narrow ridge axis moves into the area Monday night. This ridge will bring in drier air along with subsidence effectively ending any linger lake induced snow showers. The ridge axis continues to move across the region Tuesday, keeping weather conditions quiet with seasonal temperatures. There will be some improvement in temperatures Tuesday with most highs in the mid to upper 30s. The next weather system takes the form of a mid-level closed low, which will work through the Ohio valley Tuesday night. High pressure just to the north of the region likely keeps this system just off to our south. Still some question to how far north the northern edge of the precipitation shield gets, but at this point will continue to suggest that the area remains dry Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A ridge building across the Rockies, will allow for a deep trough to lie across the Great Lakes and the Atlantic states. This longwave pattern will then remain "stagnant", due to the omega blocking pattern that sets up from the middle of next week through early next weekend. While the longwave pattern will remain stagnant, due to the longwave trough across the area, multiple shortwaves will dive through the base of the trough. Model guidance continues to differ regarding timing and placement of these features. This being said there remains some confidence that a system will pass across the Northeast late Thursday into the weekend. Outside of this, the weather should remain on the drier side. Temperatures will continue to remain slightly above normal throughout the end of the week and into the weekend, however a general cooling trend will be in place. Highs will range in the upper 30s to low 40s Wednesday and Thursday with highs in diving into low to mid 30s by Saturday. Lows will range in the upper 20s and low 30s Wednesday and Thursday night before dropping into the upper teens to low 20s by the weekend. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... Low pressure will pass by just to the south of the area today with its precipitation shield continuing to expand north into the region. Expect mostly rain initially, then the higher elevations of the Southern Tier and western Finger Lakes will change to wet snow by this afternoon. The change to wet snow will then gradually progress to lower elevations during the day. CIGS will remain IFR today and vsbys will continue to be variable, and highly dependent on where and when the change over to snow occurs. Tonight...low pressure tracks out to sea but northerly upslope flow and some lingering snows will maintain IFR conditions overnight. Outlook... Monday...MVFR/IFR in snow showers in the morning, improving to VFR/MVFR in the afternoon. Tuesday and Wednesday...Mainly VFR. Thursday...VFR/MVFR with a chance of rain/snow showers. && .MARINE... Low pressure will track just south of the area through the OH/VA this morning, then give way to a secondary coastal low by this afternoon off the Mid Atlantic. Northeast winds will increase to the north of this system, bringing a period of Small Craft Advisory conditions to the south shore of Lake Ontario and a portion of Lake Erie through Sunday night. Elevated north winds will last into Monday on the eastern portion of Lake Ontario, with light winds returning Monday night. && .HYDROLOGY... All of the faster responding creeks and rivers have already crested and are falling following the excessive runoff from rain and snowmelt earlier in the week. A few of the slower responding river stretches are still rising however. Black Creek near Churchville has risen just above flood stage and will remain there until falling below flood stage on Sunday morning. Expect minor flooding along Black Creek in and near Churchville. Tonawanda Creek has crested at the upstream points including Batavia, with the crest now working its way downstream along the Erie/Niagara County border. This stretch is slow moving with a very low gradient, and will continue to slowly rise through at least Sunday or Sunday night at the gauge point near Rapids, likely reaching flood stage. The river will remain high through at least Monday before falling by Tuesday. A number of the swampy/slow moving tributaries in the northern part of Amherst, Clarence, and Newstead may also see low land flooding as water backs up from the main channel on Tonawanda Creek. Expect the typical side roads in this area to be closed due to flooding over the next few days. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Weather Advisory until 4 AM EST Monday for NYZ012>014- 021. MARINE...Small Craft Advisory until 1 AM EST Monday for LEZ040-041. Small Craft Advisory until 1 AM EST Monday for LOZ042. Small Craft Advisory from 10 AM this morning to 1 PM EST Monday for LOZ043-044. && $$ SYNOPSIS...AR NEAR TERM...AR SHORT TERM...TMA LONG TERM...EAJ AVIATION...AR MARINE...AR HYDROLOGY...Hitchcock/JLA