583 FXUS61 KBUF 210559 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 159 AM EDT Sat Aug 21 2021 .SYNOPSIS... A warm, humid airmass over the Northeast will provide for continued potential for some showers and thunderstorms through Monday. This will especially be the case during the daytime hours, inland from the lakes. High pressure will then build across the area on Tuesday. && .NEAR TERM /THROUGH TODAY/... Patchy fog will again develop overnight, but this will be somewhat mitigated by mid and high clouds which IR satellite imagery shows streaming across much of the region. The circulation around a closed upper level low across the mid- Atlantic states will send maritime moisture across the region. As this system interacts with tropical system Henri, this will bring progressively more moisture with precipitable water values increasing to almost 2 inches. This combined with diurnal instability will support generally scattered showers and thunderstorms this afternoon and early evening. Moist airmass supports the potential for locally heavy rainfall, with mesoscale guidance suggesting the greatest risk for heavy rain across the eastern Lake Ontario region. Otherwise, temperatures will remain above normal with highs in the lower to mid 80s today. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... A closed upper level low across the mid-Atlantic states will interact with tropical system Henri during this period. While there will be no direct impacts from Henri across our region with its center passing by well to our east...the weak mid-level flow will still slowly funnel some of its associated tropical moisture back across our region. This will result in continued sultry conditions along with the risk for some scattered showers and thunderstorms...with the greatest potential for these found during the afternoon and early evening hours of both Sunday and Monday... in tandem with peak diurnal heating and resultant instability. Overall coverage will be greatest across eastern portions of the Finger Lakes and North Country which will be closest to the moisture source...with both diminishing with increasing westward extent. While the convection will tend to be mainly scattered in nature...a few slow moving storms with locally heavy rainfall will be possible. With respect to temperatures...expect daytime highs to primarily range from the lower 80s across the higher terrain to the mid and possibly a few upper 80s across the lower elevations...while nighttime lows range from the low to mid 60s across the Southern Tier to right around 70 near the lakeshores. At the same time... humidity levels will remain uncomfortably high throughout. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Generally quiet weather anticipated with muggy and very warm conditions through Wednesday as weak sfc ridge extends in over the region. Might see highs pushing into the upper 80s to near 90F as H850T climb to +20C. Any relief likely won't come until the latter half of the week. This is when a cold front nears the eastern Great lakes, but there still is a lot of uncertainty with the timing of the front. Have added chance POPs, no higher, for Wednesday night and Thursday time frame. After that, there isn't all that much agreement amongst the various guidance packages from sfc ridge build in and dry to a continuation of chance showers and storms. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... The main concern will be the potential for fog development through 13Z today. More high clouds than last night, and suspect this will result in more light (MVFR) fog than there was last night. Expect areas of IFR across the Southern Tier (KJHW) where satellite imagery shows more breaks in the high clouds. Any fog will quickly dissipate after 13Z, with mainly VFR flight conditions today. Scattered showers and thunderstorms will develop this afternoon and early evening with localized MVFR or lower conditions. Best chance for these will be east of Lake Ontario (KART). More widespread fog is likely to develop tonight, with areas of IFR likely. Outlook... Sunday through Monday...Mainly VFR with the chance of showers and thunderstorms. Tuesday and Wednesday...Mainly VFR. && .MARINE... Winds will be weak with a light to gentle breeze through most of the weekend on both lakes. Some showers and thunderstorms will be possible through the weekend as well, as the active pattern continues. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Apffel/SW NEAR TERM...AR/Apffel SHORT TERM...Apffel/JJR LONG TERM...AR AVIATION...AR/Apffel MARINE...Apffel/Fries