384 FXUS61 KBUF 130536 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 136 AM EDT Mon Jul 13 2020 .SYNOPSIS... A couple weak upper level disturbances will usher in cooler and less humid air through Monday. There may some showers, especially on Monday afternoon when some thunderstorms may also occur. Heat and humidity will increase during through the rest of the week, with the best chance for widespread showers and thunderstorms on Thursday. && .NEAR TERM /THROUGH TODAY/... A weak upper mid level trough and sfc trough moving across the region touching off some thundershowers over the St. Lawrence river valley. Otherwise, it will remain quiet overnight as drier air moves in. A strong shortwave will pivot around a longwave trough centered near the Ontario/Quebec province border on Monday. Shortwave arrives during peak heating of the day. This combined with even modest diurnal instability (MLCAPES 750 j/kg, maybe 1000 j/kg) will support a few showers in the morning and a decent expansion of scattered showers and thunderstorms in the afternoon, especially from the Southern Tier to the Finger Lakes and east of Lake Ontario. Coverage will be most widespread east of Lake Ontario where less lake modified airmass will be present with the nw flow. The least coverage will be across the Niagara Frontier closer to the Lake Ontario shore. This setup with nw flow aloft and steeper mid- level lapse rates, fairly low freezing levels and modest shear of 25 kts could result in a few stronger storms during peak heating. Best chance of that will be east of Lake Ontario. The trough will also bring in cooler air aloft, with 850mb temperatures down to around +11c. So far Buffalo, Rochester, and Watertown have reached 80F every day this July, but this streak may be broken with forecast highs only in the mid to upper 70s on Monday. A few showers may linger east of Lake Ontario nearest to the departing trough, but otherwise it will be just cool and dry Monday night. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... An upper level ridge will move over the Great Lakes while an exiting trough over New England maintains a northwest flow Tuesday. As surface high pressure extends into the eastern Great Lakes, northwest flow will diminish. Enough moisture will be present to produce scattered showers mainly east of Lake Ontario through the afternoon. Mostly dry conditions expected elsewhere as a cumulus field forms across inland portions of the region. Can't rule out a few brief afternoon showers across the higher terrain of western NY. Temperatures will rise into the upper 70s to low 80s. Surface high pressure moves overhead Tuesday night resulting in calm and clear conditions. Low temperatures will fall into the mid to upper 50s and near 60 along the lake shores. The upper level ridge axis becomes centered overhead Wednesday and mostly sunny and dry conditions are expected. Warm air advection will begin across western NY Wednesday afternoon. Afternoon highs will range from the mid to upper 80s across western NY to the low 80s east of Lake Ontario. The ridge axis moves into New England Wednesday night. An elevated warm front will move across the region while surface low pressure approaches from the Mid-West. Shower chances increase across western NY into Thursday morning. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Model consensus brings a convectively driven shortwave and low across the region on Thursday which is likely to produce showers and thunderstorms. Mostly dry Friday and Saturday when a zonal flow becomes established across the Great Lakes region with an elongated area of high pressure anchored across the lower half of the Lower 48. The next shortwave will approach the region Sunday with a small chance of showers and storms. Heat and humidity will gradually increase, with high temperatures near 90 again during the weekend. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... Mainly VFR flight conditions overnight. A few thundershowers across the eastern Lake Ontario region through 08z as weak trough finishes crossing the region. NW flow behind this boundary will increase cloud cover with areas of MVFR developing around 08Z. Patchy fog possible across the Western Southern Tier, but its questionable if it will reach the KJHW terminal. MVFR to VFR cigs on Monday. Best chance for scattered showers and some thunderstorms will be Monday afternoon east of Lake Ontario, including at ART. Outlook... Monday Night...MVFR to VFR. Tuesday and Wednesday...VFR. Thursday...VFR/MVFR with a a chance showers and thunderstorms. Friday...Mainly VFR. A small chance of showers. && .MARINE... Winds have increased in wake of a weak trough crossing the region resulting in choppy conditions across Western Lake Ontario and along eastern shore of Lake Erie. Conditions will stay below small craft advisory criteria though. High pressure will then provide gentle to occasional moderate breezes Monday through Wednesday. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Apffel/JLA/TMA NEAR TERM...Apffel/JLA/TMA SHORT TERM...HSK LONG TERM...Apffel AVIATION...Apffel/JLA/TMA MARINE...Apffel/JLA/TMA