Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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914 FXUS61 KBUF 070809 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 409 AM EDT Tue May 7 2024 .SYNOPSIS... High pressure will bring abundant sunshine today, with temperatures quickly warming after a cool start. A warm front will then move across the area tonight, with an area of showers and a few thunderstorms crossing the area from southwest to northeast. The showers will exit the eastern Lake Ontario region Wednesday morning. Dry weather will then prevail most of the time for the rest of Wednesday, although a few more showers and thunderstorms are possible later in the afternoon and evening, especially east of Lake Ontario. Unsettled weather will then last Thursday through the weekend with a series of low pressure systems crossing the region. && .NEAR TERM /THROUGH WEDNESDAY/... High pressure will move from Ontario and Quebec east across New England today. Full sunshine will prevail most of the day, with a modest increase in high clouds later this afternoon. Temperatures are in the 40s across the bulk of the area early this morning, and even a few upper 30s east of Lake Ontario and in the colder sheltered valleys of the Southern Tier. Temperatures will quickly warm today after the cool start, with highs in the low to mid 70s in most areas. A light northeast flow will keep the south shore of Lake Ontario much cooler. Tonight through early Wednesday morning a mid level trough will move northeast across the Great Lakes, with an associated warm front moving northeast across our area overnight. A 40+ knot southwesterly low level jet in the upstream warm sector will impinge on the warm front and enhance moisture transport and isentropic upglide. The quality of forcing and moisture continue to support the idea of an organized area of showers moving from southwest to northeast across the area overnight. Expect an arrival time of late evening in far Western NY, around or shortly after midnight for the Genesee Valley and western Finger Lakes, and the pre-dawn hours east of Lake Ontario. Forecast soundings show enough elevated instability to support a few thunderstorms as well. Wednesday, the warm front will still be over the eastern Lake Ontario region early in the morning with showers and a few isolated thunderstorms. Rain will have already ended across Western NY as the better forcing and moisture move east. The warm frontal showers will largely end by mid to late morning east of Lake Ontario. A strong mid level shortwave will then move across southern Ontario in the afternoon, crossing northern NY during the late afternoon and early evening. Diurnal instability will increase by this time, aided by steep mid level lapse rates within a remnant EML plume crossing the Ohio Valley into PA and portions of NY. The increase in large scale forcing and instability will support another round of scattered showers and thunderstorms east of Lake Ontario later Wednesday afternoon and evening. A few of these storms may contain gusty winds and small hail, with a Marginal Risk of an isolated severe storm or two per the SPC Day 2 outlook. Farther west, Wednesday will stay mostly dry from Western NY into the Genesee Valley. A relatively dry and capped warm sector will be difficult to overcome for any deep moist convection that attempts to develop. In addition, a gusty WSW breeze will develop off Lake Erie, with a stable lake shadow expanding inland during the afternoon. The best chance of a few isolated showers will be along the northern edge of the stable flow off Lake Erie, from the Niagara Peninsula east across the Niagara Frontier to areas along the south shore of Lake Ontario. Finally, an increasingly moist airmass crossing the cold lake waters will likely produce marine layer fog late tonight through Wednesday morning. Some of the Lake Erie fog will likely move onshore into downtown Buffalo for a few hours Wednesday morning. Some of the Lake Ontario fog may move onshore into Jefferson County as well. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... A weak area of low pressure will be east of the forecast area Wednesday night. Isolated showers will persist east of Lake Ontario Wednesday evening before tapering off after midnight. Dry conditions are expected across the remained of the forecast area. Mostly cloudy conditions with low temperatures in the upper 40s to low 50s. A shortwave trough across the Mid-Western states will approach the region Thursday. A westerly flow aloft will become southerly by late Thursday and moisture and warm air advection will increase the chance for showers across the region. An associated area of low pressure will move south of the forecast area through Thursday night while the shortwave trough deepens across the Northeast. While there is uncertainty in the track and strength of this system, periods of showers are likely ahead of this system Thursday into Thursday night. There is a slight chance of thunderstorms during peak heating Thursday afternoon, however confidence is low. Rainfall amounts will average 0.25-0.50 inches across the region Thursday through Thursday night. Temperatures will average slightly above normal Wednesday night and Thursday night, however a northeast wind across the region Thursday will keep high temperatures slightly below normal. && .LONG TERM /FRIDAY THROUGH MONDAY/... An upper level trough will become nestled across the Great Lakes region and Northeast through the weekend. This will bring unsettled and cooler weather across the eastern Great Lakes region. Initially, an area of low pressure should be departing to the east of the region Friday. The 00z GFS/GEFS is an outlier at this point and keeps the area of low pressure over to the region. Daytime heating and cooler temperatures aloft will likely lead to showers developing across the region Friday. Drier weather is expected Friday night into Saturday as a ridge briefly moves into the region, however any clearing and daytime heating may result in scattered showers Saturday. The upper level trough will move overhead while the surface low pressure approaches the region Sunday into Sunday night. There are low to medium chances for showers to end the weekend. The trough will move east of the region the start of the work week with chances for showers lingering into Monday. While confidence is low on the coverage and timing of showers Friday through Monday, confidence is higher that it will be a period of cooler weather across the eastern Great Lakes region. Temperatures will average below normal with temperatures reaching near normal by Monday. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... High pressure will drift east across Ontario and Quebec today, reaching New England by late afternoon. VFR will prevail areawide with clear skies and light winds. Tonight, a warm front will move quickly northeast across the eastern Great Lakes. Expect an area of showers and possibly some embedded thunder to cross the area from southwest to northeast overnight. Expect the rain to reach Western NY around midnight, then move to the eastern Lake Ontario region by daybreak. The rain will be moving into a dry airmass, so expect mainly VFR CIGS/VSBY initially. The low levels will saturate near the back edge of the rain, with areas of MVFR/IFR CIGS expanding late tonight. Outlook... Wednesday...Areas of MVFR/IFR CIGS in the morning, improving to mainly VFR in the afternoon. A chance of showers and thunderstorms, mainly east of Lake Ontario. Thursday...VFR/MVFR. Showers likely with a chance of thunderstorms. Friday...MVFR. Showers likely. Saturday...Mainly VFR. A slight chance of showers. && .MARINE... High pressure will drift east across New England and weaken today. Winds will be light for most of the area. The one exception will be the west end of Lake Ontario, where ENE winds will increase this afternoon and evening, producing choppy conditions on Lake Ontario west of Rochester, but winds and waves are generally expected to remain below Small Craft Advisory criteria. WSW winds will increase Wednesday, especially on Lake Erie. This will produce very choppy conditions Wednesday through Wednesday evening, possibly near Small Craft Advisory criteria. An increasingly moist airmass crossing the cold lake waters will likely produce marine layer fog late tonight through Wednesday morning on Lake Erie and Lake Ontario with visibility restrictions. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock SHORT TERM...HSK LONG TERM...HSK AVIATION...Hitchcock MARINE...Hitchcock