515 FXUS61 KBUF 011058 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 658 AM EDT Tue Aug 1 2023 .SYNOPSIS... While a very cool airmass could support spotty lake effect showers southeast of the lakes this morning...then a few instability showers well inland this afternoon...a large area of high pressure will keep the VAST MAJORITY of the region rain free through Wednesday. We can then anticipate summer warmth to return ahead of a cold front on Thursday...as a stretch of showery weather can be expected late Thursday into Friday. A look down the road at the weekend reveals that there is high confidence for fair dry weather. && .NEAR TERM /THROUGH WEDNESDAY/... The majority of the region will experience fair dry weather today... as a large area of high pressure will slowly drift across the Lower Great Lakes. There will be a few showers around though...largely due to the cool airmass that is in place. To start...a weak lake response to the single digit H85 temps could support a few nuisance showers southeast of both lakes through mid morning. As we work our way into the midday hours though...strong late summer diurnal mixing will eliminate this scenario. The cool airmass with its steep low level lapse rates will then set the stage for some 'self destruct' sunshine that will lead to a wealth of afternoon Cu and possibly some widely separated showers well INLAND from the lakes. For most areas though...the day will feature rainfree weather. It will be quite cool today with afternoon temps only reaching into the low to mid 70s. Upon the Tug Hill...the mercury may do not better than the mid 60s. As a reminder...normal highs for the start of August (just past thermal solstice) are close to 80. The expansive area of high pressure will slowly creep to our east tonight. Given the very cool airmass in place...this scenario should promote some of the coolest weather of the next week or so with mins tonight ranging from the mid 40s in the interior of the Srn Tier to the mid 50s across the lake plains. This will be nearly 10 deg f below normal values to start the month of August. The heart of the sfc high will make its way across New England on Wednesday. The weak return flow around the backside of the sfc high will establish enough warm advection to allow H85 temps to climb back to arnd 12c...which in turn will enable our afternoon temps to climb into the mid to upper 70s.This should make Wednesday one of the nicest days in the forecast package with abundant sunshine and comfortable conditions. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... High pressure along the Northeast coast will exit out to sea early Wednesday night. Meanwhile...initial shortwave energy dropping through the longwave trough will be in the process of racing across E. Ontario/Quebec. This feature and a warm front working through the area will bring increasing chances for showers...mainly concentrated across the North Country and St. Lawrence Valley. Have added chance POPs for this region to cover this threat overnight. Elsewhere...dry weather will likely persist for all of western New York. Otherwise...southerly flow ahead of a slow approaching cold front will usher in a somewhat muggy and milder airmass overnight as we head into Thursday. This will help to add 5F to 10F onto overnight lows temps which will be found mainly in the upper 50s to 60s across western New York...a bit cooler across interior locations of the North Country. Shortwave energy will continue to dig south and east Thursday which will slowly push a cold front towards the Lower Lakes. A prefrontal trough ahead of the front is advertised to work through the region in the mid/late afternoon...the best shot to see showers or thunderstorms still appears to be focused across eastern and southeastern portions of the area. This is where the higher PWATs reside of +1.25 inches. That said...the SVR potential still looks rather limited or paltry at this point given shear values of < 30 knots and then only 500-1000 j/kg SBCAPE. Thursday evening/night...the shortwave and weak sfc reflection over Quebec will slowly push the cold front into and through the Lower Lakes. There will be some chances for showers or a storm as the front slowly sags into and through the area. on Friday...the mid- level circulation to our north will send a secondary frontal boundary southward towards and then through the region. This will again touch of a few more showers or even a thunderstorm in the afternoon into the evening. It will also signal the arrival of cooler aloft with H850 temperatures dropping to +7C to +10C. After that...any showers or storms will fade as we move through Friday night. This will occur with the loss of daytime heating and as drier air circulates into the Lower Lakes overnight. && .LONG TERM /SATURDAY THROUGH MONDAY/... High pressure builds in at all levels on Saturday which will provide fine August weather across the entire area. Highs will top out in the 70s areawide. Dry and quiet weather continues Saturday night as highs pressure slides overhead. Lows expected in the 50s to low 60s. Surface high pressure will slowly slide east of the area of Sunday but will maintain dry weather. Temperatures will be a bit warmer as southerly flow develops on the western flank of the departing high. Looks for temps in the upper 70s to low 80s. After Sunday...still a lot of uncertainty in regards to the next upstream shortwave which is advertised to potentially track across the upper Midwest and then into the Great Lakes region. Have capped POPs for now in the slight chance/chance range below NBM guidance for Sunday night/Monday...atleast until there is better agreement with the shortwave overall evolution. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... After the morning fog and stratus burns off across the Southern Tier...all of western and north central New York will be able to enjoy fine VFR weather with light winds. VFR conditions will persist tonight...although patchy fog will once again develop across parts of the Southern Tier after 08z. Outlook... Wednesday...VFR. Thursday and Friday...Mainly VFR with a chance of showers and thunderstorms. Saturday...VFR. && .MARINE... While high pressure over the region today will only allow for light winds and negligible wave action...there will still be the risk for isolated waterspouts through the morning hours. A very cool airmass has allowed for land breeze boundaries to drift out across both lakes early this morning...and these will serve to focus enough low level convergence to support widely separated showers or isolated waterspouts. The KBUF radar confirmed the presence of a such a boundary at 11z and surrounding observations added evidence of this low level focusing feature. Light winds and minimal waves will then persist tonight through Wednesday...as the area of high pressure will slowly exit to our east. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...AR LONG TERM...AR AVIATION...RSH MARINE...RSH