Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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854 FXUS61 KBUF 300206 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1006 PM EDT Sat Jun 29 2024 .SYNOPSIS... A cold front will move across the region overnight, producing a few showers and thunderstorms with its passage. The front will bring less humid conditions and drier weather for Sunday. High pressure will build in on Monday which will bring fair and dry weather which will last through Tuesday. && .NEAR TERM /UNTIL 6 PM SUNDAY EVENING/... Late this evening, radar shows most of Western NY is rain- free, with scattered showers and storms east of Lake Ontario. There remains some instability in place tonight with LAPS showing CAPE 500 to 1000 J/Kg. Wind shear has diminished from earlier, but the 00Z Buffalo sounding still has winds of 40 knots at 850mb. There remains a marginal risk for severe weather overnight, mainly just ahead of the cold frontal passage. Storms may also produce brief heavy downpours with precipitable water values still near 2 inches ahead of the front. Patchy fog is also possible. With the passage of the initial cold front it will become quite breezy Sunday, with increasingly more comfortable conditions due to the tumbling Td`s. Interestingly enough...our high temperatures are advertised to peak in the low to mid 70s by midday/early afternoon then slowly falling thereafter. This is unusual for this time of year... so this gives you a semblance of how strong the cold advection will be in the wake of the first cold front. MaxTs Sunday will generally be found in the 70s. && .SHORT TERM /6 PM SUNDAY EVENING THROUGH TUESDAY NIGHT/... Dreary weather Sunday night as an upper level trough axis and secondary cold front pivot southeast through the eastern Great Lakes. With recently sampled lake temps near +21C, 850H temps bottoming out near +5C and northwesterly upslope flow coupled with weak difluence aloft will maintain a wealth of cloud cover and some scattered showers overnight. Will continue to hedge above blended guidance for sky/PoPs as it continues to be too aggressive with the overnight clearing and drying given the expected pattern. Greatest chances for any measurable precip will be earlier in the night east of Lake Ontario and across the higher terrain of the Finger Lakes region, while far western NY should begin clearing out very late in the night. Otherwise, insulation from the extra cloud cover should somewhat balance out with the chilly airmass and yield comfortable sleeping temperatures in the 50s, with upper 40s possible across the hilltops. Excellent weather will then be in place as we move into the first day of July as a broad area of surface high pressure initially centered over the western Great Lakes Monday morning migrates east, being directly overhead by Monday night before shifting off the New Jersey coast by Tuesday evening. Temps aloft will already begin warming Monday, though given the cool start surface temps will likely only reach the upper 60s and low 70s under mostly sunny skies. Monday night will again be on the cool side owed to the clearer skies, with lows ranging from the upper 40s across the interior hilltops to mid 50s near the lakeshores. Mid/high clouds will increase through the day Tuesday out ahead of a warm front lifting through the Ohio Valley. Temps at the sfc and aloft will continue to warm on the western periphery of the surface high Tuesday and Tuesday night, with temps topping out in the upper 70s to low 80s and lows ranging in the 60s respectively. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... Warmer, unsettled weather returns to the forecast as we move later into the week. This comes as weak mid-level ridging shifts east of the Great lakes Wednesday as is replaced with nearly zonal flow aloft extending back toward the lower Midwest. Meanwhile, a weakening mid-level trough will trudge east across James Bay from northern Ontario to Quebec, causing several shortwave disturbances to ripple through the overhead zonal flow, bringing on and off chances for showers and thunderstorms through the end of the week. The first of these opportunities for wet weather will arrive Wednesday afternoon. A large surface low attendant to the trough near James Bay will sag its elongated cold front southeastward across Ontario Province and towards the eastern Great Lakes. Diurnal convection will be possible during peak heating hours as the forecast area sits within the system`s warm sector. A more widespread round of showers and possibly a few additional thunderstorms is expected Wednesday night as the front moves through then stalls just south of the region, before the area dries out late Wednesday night into Thursday morning. Forecast uncertainty increases as we move further into Thursday and towards the weekend. Long range guidance is in general agreement on the stalled frontal boundary remaining to our south through Independence Day, with an area of subsidence drying extending across the forecast area from the upper Great Lakes. This being said, the GFS is much further north with the placement of the boundary than the ECMWF/CMCNH, both of which hint at some possible light diurnal shower activity developing. This is reflected in the forecast as low- end chances for showers (15-20%) in most areas Thursday afternoon and evening, with slightly better chances (~30%) across the Southern Tier in closer proximity to the boundary, where some thunderstorms may be possible as well. Thereafter, a compact shortwave racing across the Lower Great Lakes/Ohio Valley Thursday night will take aim at the forecast area by Friday morning, followed by a larger surface low which will move across the Great Lakes Saturday. As is typical at this range, uncertainty is high in strength, timing, and track of these systems which will also likely be influenced by how they interact with the stalled boundary south of the area. Therefore have stuck close to deterministic NBMs Chc PoPs Friday through Saturday until details come into better focus. For temperatures this period...Summer`s warmth will return to the forecast area out ahead of the cold front Wednesday, with highs well into the 80s likely in most areas. Temperatures cool a few degrees with a bit less humidity by Thursday. Temperatures Friday will be similar, likely cooling a bit more to the upper 70s/low 80s by Saturday. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... A mix of MVFR and VFR cigs late this evening, with lots of lingering low level moisture. Scattered showers and thunderstorms ahead of a cold front which will move across the area late tonight. These will bring localized MVFR or lower flight conditions. Increasing moisture with the cold front will also bring lower cigs in the MVFR/IFR flight category. Some fog is also possible, especially east of Lake Ontario and in the Southern Tier. Showers will taper off at most locations during Sunday, and cigs will gradually lift and break up some. Expect mainly VFR flight conditions by Sunday afternoon. Outlook... Sunday night through Tuesday...VFR. Wednesday...VFR/MVFR with showers and thunderstorms likely. Thursday...Mainly VFR with a chance of a shower or thunderstorm across the S. Tier. && .MARINE... A cold front will approach the region tonight...expect fresh to strong westerlies in the wake of a front on Sunday. This will likely lead to a fresh round of headlines for at least the eastern half of Lake Ontario...while choppy conditions will be found elsewhere. Looking further ahead...high pressure drifting across the region Monday and Tuesday will offer fine conditions for recreational boating with generally light winds and negligible waves. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...AR/Apffel NEAR TERM...AR/Apffel/RSH SHORT TERM...PP LONG TERM...PP AVIATION...AR/Apffel MARINE...AR/Apffel/RSH