Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
855 FXUS61 KBUF 210627 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 227 AM EDT Fri Aug 21 2026 .WHAT HAS CHANGED... Only minor changes with this forecast update. && .KEY MESSAGES... 1) Periodic showers and scattered thunderstorms this weekend into early next week. && .DISCUSSION... Key Message 1...Periodic showers and scattered thunderstorms this weekend into early next week. Expect fair dry weather today and tonight as high pressure slowly drifts from southern Quebec to the Canadian Maritimes. Our weather will then turn more unsettled again this weekend...as upper level troughing digs southeastward across Ontario Province and eventually closes off over southern Ontario/southwestern Quebec by later Sunday/Sunday night. At the surface...an attendant elongated surface low will slowly push a warm front into our region Saturday, followed by a cold front Saturday night into Sunday morning. With respect to Saturday...guidance continues to trend a bit slower with the both the approach of the warm front and associated moisture return...with this now looking slow enough to keep us mainly dry through the early afternoon hours. As we push through the rest of the day...the approaching front/increasing moisture and modest to moderate diurnally-driven instability should still become enough to set off some scattered convection from the Finger Lakes westward... with showers/storms possibly becoming a little bit more numerous across the Southern Tier toward evening. Meanwhile further east... the eastern Finger Lakes and (especially) the North Country appear more likely to remain largely if not totally dry through sunset. More widespread showers and some embedded thunderstorms then look to follow Saturday night through Sunday morning as the trailing cold front crosses our region in concert with support from DCVA/steady height falls aloft. PWAts during this time will peak in the vicinity of 1.5"...which could lead to a few locally heavy downpours within any stronger convective cores. In the wake of the cold frontal passage...a cyclonic flow of progressively cooler air will then overspread our region Sunday through Monday...with a current multimodel consensus suggesting that 850 mb temps will bottom out in the +6C to +8C range later Sunday night into Monday. This regime will support additional scattered instability showers and a few storms Sunday through Monday...with these potentially turning a little more numerous at points in tandem with hard-to-time areas of deeper wraparound moisture and shortwave impulses pivoting around the larger-scale closed upper low. Downwind of the lakes...the progressively cooler airmass should also allow for some areas of lake enhanced/lake effect rain showers at times... with the prevailing large-scale flow focusing most of these east of Lake Erie and east-northeast/east of Lake Ontario. Improving conditions are then expected Monday night and Tuesday as the upper low ejects northeastward across Quebec...and high pressure and drier air builds across our region at the lower levels. With respect to temperatures...these will generally be seasonable through Saturday...before falling a bit below normal for both Sunday and Monday. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... High pressure sliding from southern Quebec to the Canadian Maritimes will maintain fair dry weather across our region through tonight... and consequently VFR conditions will largely predominate. The exceptions to this will be within areas of IFR/LIFR river valley fog across the Southern Tier/east of Lake Ontario and patchier MVFR/ IFR fog across the Finger Lakes/central New York early this morning...and then in somewhat patchier valley fog across the interior of the Southern Tier (away from KJHW) later on again tonight. Outlook... Saturday through Monday...Periodic showers and isolated to scattered thunderstorms with associated MVFR/IFR...with mainly VFR expected outside of any precipitation. Monday night and Tuesday...Scattered showers and associated restrictions east of Lake Ontario diminishing...otherwise mainly VFR. && .MARINE... Surface high pressure will exit into New England today...with light/variable winds generally giving way to a light to modest easterly to northeasterly flow...though some localized onshore flow may still develop within the still-weak gradient. Modest southeasterly to southerly flow will then develop tonight and Saturday as the ridge exits off the east coast...and elongated low pressure pushes east across the central Great Lakes and Southern Ontario. This low will push its warm front and trailing cold front across the Lower Great Lakes later Saturday through Sunday morning. While the flow across our region during this time frame should remain modest to moderate and thus generally unsupportive of conditions reaching SCA criteria...these boundaries will help generate periodic showers and scattered thunderstorms...a few of which could produce locally higher winds and waves. Following the passage of the cold front a cyclonic...west- southwesterly to westerly flow of cooler air will overspread the Lower Lakes region Sunday through Monday. This may support some SCA- worthy conditions on both lakes at points...and (while not explicitly mentioned in the forecast yet) the chance for some waterspouts. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ DISCUSSION...JJR AVIATION...JJR MARINE...JJR