Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 070909 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 509 AM EDT Wed Jun 7 2023 .SYNOPSIS... A period of more unsettled weather continues with daily chances for some showers and a few thunderstorms, with the best chances for showers across the eastern portions of the region. Smoky skies with haze and smoke from the wildfires across eastern Canada will likely persist across the entire region through the end of the week. Cooler than normal temperatures can be expected the rest of the week. && .NEAR TERM /THROUGH TONIGHT/... A few clouds are drifting south across Finger Lakes and there is patchy fog along the Black River Valley. Leading edge of thickest wildfire smoke plume is moving across the Niagara Frontier to the eastern Lake Ontario region. Observations are reporting the "cloud base" of this wildfire smoke plume of 2500-3000 ft. This is a very low altitude smoke plume and it will not take much mixing to bring dense smoke to the sfc through the morning. More details on expected evolution of this smoke in a bit. In the larger scale, the upper low that was over Nova Scotia on Tuesday retrogrades into northern New England through tonight. Deep moisture and widespread light rain that is occurring over eastern Quebec and western New England figures to rotate west as well. By late afternoon, widespread light showers with no thunder will begin to move across the eastern Lake Ontario region. As this occurs a sharper trough will swing westward and as a result those showers will continue to try to expand westward across the Finger Lakes and even toward Rochester this evening. Moisture not near as expansive farther west than that, so through at least tonight, western NY will be on the outside looking in for any rainfall. Yet, even where it will rain in our area, rainfall amounts look pretty light (less than 0.25 inch) regardless. This is the sensible weather aspect of the forecast. Now to the wildfire smoke that is becoming a bigger issue as it is mixing to the sfc. NYS DEC has an Air Quality Alert for most of our forecast area. After a very dense plume of smoke moved to the sfc and impacted much of our area on Tuesday, as mentioned another plume of thicker smoke that has been shown by RAP/HRRR smoke models for a couple days is beginning to arrive from the north. We have had a mix of haze and smoke in the obs since yesterday with some spotters reporting vsby down to less than 1 mile. As this point, until we see otherwise, expect similar conditions today especially once even weak daytime mixing begins so have included both haze and smoke for the forecast with low visibility. Already starting to see vsby less than 2 miles in parts of our area even before daybreak. Based on obs upstream north of Lake Ontario and now along the south shore of Lake Ontario, seems that we`ll be dealing with sky even more opaque than Monday where the sun was barely visible at times due to such thick and low altitude smoke. That smoke layer is even lower today. As the trough alluded to earlier swings westward across the eastern Lake Ontario region, the haze and smoke should diminish there this evening and this is also showing up in the modeled smoke forecasts, but otherwise the haze and smoke in some shape or form will persist over the rest of the area through tonight. High temps today with the shroud of smoke will stay in the 60s. Normal highs are in the low to mid 70s. Lows tonight will be in the 40s though readings could drop into the upper 30s again across Southern Tier and east of Lake Ontario. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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Upper level low still spinning over northern New England to start our Thursday, now looks to retrograde a bit further west during the period, which will bring this feature a bit closer to our area than previously forecast. Good news is this will bring better chances for some much needed rainfall to our region during this timeframe. Instability and moisture profiles look a bit better during this time, so coverage of showers and thunderstorms should be somewhat more expansive (and western extent) than previous days with portions of the Southern Tier, Finger lakes, and North Country having a shot at some much needed rainfall. This will be maximized during the afternoon and early evening hours both Thursday and Friday during max heating, with much lesser chances during the overnight hours. In fact, Friday be the most active day in terms of shower and storm coverage as activity is enhanced further owed to a potent shortwave moving across the area during the peak heating hours. Areas across western NY closer to the Lakes will see lesser chances for any meaningful precipitation. That said, being that this will be mainly convective activity, the higher rainfall amounts will mostly be localized. Otherwise, with little change in our general wind flow through the end of the period due to the upper low sitting over the Northeast, smoke issues may still be a concern through the end of the work week. The core of the coolest air will move into the area Thursday, resulting in the coolest day of the week ahead. Daytime highs will be some 10-15 degrees below average, with temperatures struggling to get out of the upper 50s across the inland higher terrain, with lower to mid 60s elsewhere. Airmass modifies just a bit by Friday, with highs mainly ranging through the 60s, which is still some 5-10 degrees below average.
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On Saturday, the persistent upper level low will finally depart off to our east, with weak shortwave ridging briefly building in aloft between this system and the next shortwave trough dropping from central Canada to the upper Great Lakes. This will result in a drier day for most areas, although areas from the Finger Lakes to the North Country could still see a few more widely scattered showers as one final shortwave impulse dives around the western periphery of the departing upper low. Otherwise, we will see a warmer day with rising heights/temperatures aloft allowing surface temps to climb back to the low and mid 70s, with some upper 60s still found across the higher terrain. Shortwave ridge over the area Saturday night will provide a mainly dry night, with lows falling back to the upper 40s to mid 50s. The guidance suite continues to suggest that the next aforementioned shortwave trough diving south out of Ontario Province will close off into yet another upper level low over the central/upper Great Lakes between later Saturday night and Sunday, then continue to impact our region through at least the first half of next week. Model guidance has come into better agreement over past couple of runs on the overall track of this system taking on a more easterly trajectory, however there is still some discrepancy with respect to how quickly this system meanders its` way to the east. Overall, this is good news as this increases the chances of our area seeing some much needed, more widespread rainfall. Capped PoPs in the high chance range through the end of the period for now, mainly due to the uncertainty in timing that still remains. Otherwise, temperatures for this time frame look to be right around normal, with daily highs mainly ranging through the 70s.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... Smoke is the main concern for aviation. Widespread MVFR visibility early this morning will lower to IFR over much of the area this morning as the thickest plume of smoke moves through with even weak daytime mixing. Slight improvement this afternoon back to mainly MVFR. Based on multiple observations across the area, expect effective "cloud" base of the smoke layer to be around 2-3kft much of the time today. In terms of weather, rain showers will move from east to west into the eastern Lake Ontario region late this afternoon and settle southward across the Finger Lakes later this evening and overnight. Some showers could reach as far as western NY. Outlook... Thursday and Friday...Mainly VFR. Chance of showers each day. Saturday...Mainly VFR. Sunday...Mainly VFR. Chance of showers. && .MARINE... Mainly northerly component winds will prevail through the rest of the week. At this time, conditions look to remain below Small Craft Advisory thresholds, but it will be choppy at times with waves peaking at 2-3 feet. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Apffel/TMA NEAR TERM...JLA SHORT TERM...JM LONG TERM...JM AVIATION...JLA MARINE...Apffel/TMA is the U.S. government's official web portal to all federal, state and local government web resources and services.