983 FXUS61 KBUF 211310 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 910 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 TONIGHT/... Radar imagery showing an area of showers from southern Oswego County to the western Finger Lakes and Rochester at mid morning. These showers will continue to drift westward in a weak easterly flow regime, drawing Atlantic moisture back westward into the area. The most concentrated area of showers through midday will be found across the Genesee Valley and Ontario/Wayne counties. As the upper level 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. Any lingering showers or storms should end by late evening, leaving most of the night rain-free. Model guidance suggests there will be less cloud cover tonight. This will allow for fog to be more widespread, especially across far Western New York where the most clearing is expected. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... An upper level trough and low over the region combined with a tropical airmass will once again increase the chance for showers and thunderstorms for the day on Sunday. As the day progresses, there will also be the chance for some influences from currently Tropical Storm Henri over the far southeastern portion of the forecast area. The main area of rain associated with the storm will stay east of the area, but the plume of moisture that is ahead of and with the storm will push into the eastern portions of the area. This will bring the increased potential for showers and thunderstorms with some brief moderate to heavy rain possible at times, especially for areas of the Northern Finger Lakes, and portions of the Southern Tier, and the North Country. Daytime diurnal heating will also help enhance any shower/storm potential during the day on Sunday. Sunday night, showers should diminish from west to east with the loss of daytime heating, but with the tropical airmass and the tropical storm to the east, showers should still linger through the night for the eastern portions of the area. Monday, again another active day, with showers and thunderstorms possible, especially for the eastern portions of the area. But daytime heating and a tropical airmass will provide for the chance of showers and storms across a good portion of the area. The track of Tropical Storm Henri will be monitored closely as the western edge of the storm may approach the North Country during the day on Monday. Most guidance doesn't push the system that far west, but a few global models continue to push the system slightly closer to these eastern portions of the forecast area. If Tropical Storm Henri does end up tracking east a bit quicker on Monday, then that will also pull the upper level trough east as the storm gets phased into the upper level pattern. This would result in less showers overall as well for the entire area as some of the moisture will push east and the upper level support of the trough will exit the area. Monday night, any showers and storms should taper off from west to east after sunset. Tropical Storm Henri should track away from the area on Monday night, further reducing the potential for showers/rain associated with the system. Daytime temperatures on Sunday and Monday will be in the upper 70s to mid 80s with humid conditions making both days uncomfortable. Night time lows will be in the low 60s to near 70 each night. && .LONG TERM /TUESDAY THROUGH FRIDAY/... A shift in the upper level pattern will lead to some quieter weather for most of the long term period. Warm temperatures and fairly humid conditions will persist through the week before a cold front moves through late Wednesday into Thursday. This will also provide the best chance for showers and thunderstorms during the long term period. Behind the passing cold front, temperatures will cool to near normal and humidity levels will also lowers as an area of high pressure over southern Canada tracks east along the international border. Temperatures will be in the low to upper 80s for Tuesday and Wednesday, and cool some to the upper 70s to mid 80s for Thursday. Once the cold front has fully crossed the area, and cold air advection cools temps, highs on Friday will be in the low to upper 70s. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... An area of showers from the Genesee Valley and western Finger Lakes to southern Oswego County will continue to drift westward through midday, with mainly VFR CIGS/VSBY. Additional showers and a few thunderstorms will develop this afternoon and early evening, especially across the Southern Tier, Finger Lakes, and North Country. These may produce localized MVFR or lower conditions with the best chance of these east of lake Ontario (possibly impacting KART). Any showers will taper off by late evening. There should be less high clouds tonight, with fog expected to be more widespread and possibly more dense tonight. Areas of IFR likely. Outlook... Sunday through Monday...Mainly VFR with the chance of mainly afternoon and early evening showers and thunderstorms. Tuesday...VFR. Wednesday...Mainly VFR. A chance of showers. && .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 NEAR TERM...Apffel/Hitchcock SHORT TERM...SW LONG TERM...SW AVIATION...Apffel/Hitchcock MARINE...Apffel/Fries