343 FXUS61 KBUF 290224 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1024 PM EDT Tue Jul 28 2020 .SYNOPSIS... Mainly dry weather will persist tonight. A weak cold front will then push through the region on Wednesday, offering us another opportunity for a few showers and scattered thunderstorms. The remainder of the week will feature mainly dry weather with temperatures near average. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... IR satellite imagery showing just a few patches of clouds from the Niagara Peninsula to Rochester and over Lake Ontario late this evening, the remnants of a convergence zone along the northern edge of the Lake Erie lake breeze. Otherwise the rest of the area will be mainly clear through the early overnight hours, with a modest increase in clouds late tonight ahead of the next system. Lows will drop back into the mid 60s in most locations, with upper 50s across the Southern Tier valleys and Lewis County. An area of convection is developing near central Lake Michigan this evening, tied to a subtle shortwave and small mid level jet max. Most global and high-res CAMS guidance holds this area of showers together overnight, with a weakening area of showers moving into Western NY by Wednesday morning. These showers will head towards the Genesee Valley and western Finger Lakes and weaken further by mid to late morning. Then, arrival of a weak cold front and shortwave rotating through on Wednesday will result in additional scattered showers and some thunderstorms during the afternoon. Instability (MLCAPES may reach 1000j/kg) and deep layer shear (at least 30 kts) will be sufficient for a few stronger storms with small hail and gusty winds the primary hazards. The degree of destabilization will be complicated by the morning showers and clouds, but if they exit fast enough some sunshine may develop for a few hours. SPC has outlined much of our forecast in an area of marginal risk for severe thunderstorm activity (eg. isolated severe storms). If timing of the shortwave is slower more of the area could see convection. If shortwave comes in quicker though, most focus for convection would be mainly from Southern Tier/Finger Lakes. In either case, most showers and thunderstorms will have run their course by early evening. Later Wednesday night, given some lingering low-level moisture behind the cold front, it may become cool enough aloft to support (H85 temps 11-12c with lake temps around 25c) to support a lake response in the westerly low-level flow, so carried a mention of some showers downstream of the lakes even overnight. Patchy fog in the valleys of the Southern Tier looks like a good bet late Wednesday night behind the cold front. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... An axis of an upper level trough will travel eastward across the eastern half of the Great Lakes and New England during the Thursday through Friday night timeframe. Meanwhile, a shortwave will traverse through the bottom of the trough and increase the potential for showers and thunderstorms Thursday. Some disagreements continue to lie within the model guidances in regards to the amount of instability on Thursday and therefore kept with the previous forecast of the potential for thunderstorms. While the NAM drapes higher CAPE values across the forecast area, other model guidances lie the higher amounts of instability to our south in Pennsylvania. As the shortwave trough exits the region, shower and thunderstorm potenial diminishes across the forecast area Thursday night into Friday. A slight chance for showers on Friday as the axis of the upper level trough crosses the state. Surface high pressure will build in across the eastern Great Lakes Friday night through Saturday night, bringing a period of primarily dry weather. Temperatures during this time will climb up into the upper 70s to low 80s. && .LONG TERM /SUNDAY THROUGH TUESDAY/... A positively tilted trough spanning southward across the Northern Great Lakes to the southeastern Plains will slowly lift northeastward across the eastern third of the CONUS during the later half of the weekend and into the first part of the work week. As such, an associated surface low will track northeast across Lake Erie and Lake Ontario Sunday, increasing chances for showers and thunderstorms across the forecast region. With the departing surface low and passage of the upper level trough axis will continue the chances for showers on Monday. A large area of surface high pressure will dominate across the Great Lakes, spanning into the region Tuesday which will promote dry weather for the day. Temperatures for the later half of the weekend and the first couple of days of the work week will range in the mid 70s to low 80s. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Mainly clear skies will continue through the first half of tonight, with a modest increase in VFR level clouds late tonight. A weak cold front will then cross the eastern Great Lakes Wednesday. This will produce a few rounds of scattered showers and a few thunderstorms, with the best thunderstorm coverage expected from mid afternoon through early evening. Conditions will stay mainly VFR Wednesday, although the heavier showers will produce brief/local MVFR to IFR. Outlook... Wednesday Night through Friday...Mainly VFR. Scattered showers especially Thursday afternoon. River valley fog possible across the Western Southern Tier early each morning. Saturday...VFR. Sunday...MVFR/VFR with a chance of showers and thunderstorms. && .MARINE... Winds are diminishing on Lake Erie late this evening, and will continue to drop off overnight with waves also subsiding. A cold front will push across the Lower Great Lakes on Wednesday. Southwest winds will increase again ahead of the cold front, and may reach Small Craft Advisory levels for a few hours in the afternoon on Lake Erie. Winds are expected to be somewhat lower on Lake Ontario. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock/JLA NEAR TERM...Hitchcock/JLA SHORT TERM...EAJ LONG TERM...EAJ AVIATION...Hitchcock MARINE...Hitchcock/JLA