741 FXUS61 KBUF 310241 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1041 PM EDT Sun Aug 30 2020 .SYNOPSIS... High pressure will gradually push east into our area overnight and early Monday. This will support fair dry weather, while our cool airmass warms back to above normal levels. Late summer warmth can then be expected Tuesday through Thursday as we open the month of September, although it will become increasingly unsettled. && .NEAR TERM /THROUGH MONDAY/... High pressure will build into the eastern Great Lakes overnight. Clear, calm conditions will result in cool weather with patchy valley fog developing tonight. Fog may develop as early as this evening east of Lake Ontario with valley fog developing late across the western Southern Tier and western Finger Lakes. Dry conditions will persist Monday, although an incoming area of low pressure will increase cloud coverage during the afternoon. Southeast winds will increase across Western NY. Most high temperatures in the mid to upper 70s. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... Moisture will increase through this period as the Eastern Great Lakes region remains on the southeast edge of a longwave trough that is centered over Central US. In addition to moisture advected northward from the Lower Mississippi Valley, an area of low pressure meandering off the Carolinas will send Atlantic moisture inland, with a little of this moisture spilling into our eastern zones. Surface high pressure will sit over southern Atlantic Canada, helping the westerlies to steer the Carolina surface low out to sea. Tuesday a southwest flow will continue to bring a milder airmass into our region, with afternoon humidity and instability possibly fueling a few afternoon thunderstorms. Upper level forcing from convective shortwave looks to arrive Tuesday night, and will have greater coverage of chance PoPs Tuesday night for our region, while maintain the chances for storms through the night. It will remain warm Tuesday night, with temperatures some 10 to 15 degrees above normal. Wednesday will again be warm, though an afternoon breeze looks to increase as the pressure gradient tightens between a weak surface wave that will pass over the Lower Lakes and surface high pressure over Atlantic Canada...that will be bulging back westward over New England. This weak surface wave will bring added convergent lift to again product scattered convection to our region on Wednesday. Moisture levels may be a touch greater, thus there will be plenty of moisture for these storms to feed off from. Convection will likely diminish greatly Wednesday night as daytime instability wanes and upper level heights begin to increase. With little change to the airmass, Wednesday night will have similar low temperatures. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Thursday an upper level shortwave will be diving down across the Western Great Lakes, and will focus a sharp upper level trough and frontal passage across our region Thursday night. Convection is likely to increase Thursday afternoon, and with an uptick in the winds aloft, and increase in bulk shear...there will be prospects for stronger thunderstorms. At this time, the 12Z GFS and ECMWF are in pretty good agreement with the passage of a cold front, this being Thursday night from west to east across our region. Thunderstorms Thursday night will be swept eastward, and lowering humidity will filter into our region for Friday. The upper level shortwave will still remain nearby to our west, thus chances for a few showers will remain for Friday. With a pool of cooler air dropping across the eastern Great Lakes there will be a breeze both Friday and Saturday. High pressure over the region Saturday morning will start the day comfortably cool and dry. There will be a small chance for some lake effect rain showers this to the northeast of the lakes Saturday morning, however drier air with the surface high may just limit the lake response to just clouds. The cooling will not last long as surface high pressure centered just to our south Saturday morning shifts eastward through the day, with a warming trend aloft then starting again. This surface high to our east may hold on the dry weather into Sunday, with an approaching cold front bringing increasing chances for showers towards Sunday night in the west. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... High pressure will continue to advance into the area from the upper Great Lakes. Mostly clear expected tonight into Monday. Patchy valley fog will likely produce MVFR to IFR conditions at KJHW with a lower chance at KART. VFR conditions expected Monday. Southeast winds increase across Western NY through the afternoon. Outlook... Tuesday...Restrictions possible with a chance for showers. Wednesday through Friday...Restriction possible with a chance of mainly afternoon showers and thunderstorms. && .MARINE... Surface high pressure will make its way into the Lower Great Lakes tonight, allow for lessening winds and waves. East to southeast winds will then freshen across the region on Monday, but conditions will remain below SCA criteria. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...RSH/TMA NEAR TERM...HSK/TMA SHORT TERM...Thomas LONG TERM...Thomas AVIATION...HSK/TMA MARINE...HSK/RSH/TMA