Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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865 FXUS61 KBUF 251138 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 738 AM EDT Wed Sep 25 2024 .SYNOPSIS... Weak low pressure tracking by to our west and north today will drag a wavy cold front through the region tonight. While scattered showers will be found ahead of this front today...heavier...more widespread showers can be expected tonight. Areas east of Rochester may experience some left over showers Thursday morning...otherwise high pressure will build across the Lower Great Lakes to support fair dry weather Thursday afternoon through at least Friday. Most... if not all...of the significant rains from Helene should stay to our south. && .NEAR TERM /THROUGH TONIGHT/... Regional radar shows some showers across the forecast area this morning. Drier air is moving into the forecast area as evident on water vapor imagery. Showers will mainly be confined to the northern tier of the forecast area this morning, however a few showers are possible across western NY, in vicinity of a warm front. A strong ridge is centered over the Intermountain West as a trough digs into the Mid-West and Ohio Valley this morning. A steady state area of low pressure over northern Michigan will move north- northeast today. Organized Showers have mainly moved into the Saint Lawrence Valley this morning as a low level jet exits to the northeast. A warm front will continue to lift northward from northwest Pennsylvania and move into far western NY this morning. Additional showers may blossom through daybreak. Elsewhere, mostly dry conditions expected as drier air moves into the forecast area this morning. A humid airmass (for late September standards) will draw dewpoints into the low 60s across the forecast area. The combination of daytime heating in a moist airmass and upper level diffluence ahead of the trough will likely result in showers developing this afternoon. Forecast soundings show a well saturated column with weak instability, however with theta-e advection during peak heating, can`t rule out a few thunderstorms. The trough will move east while the low drags a cold front towards the forecast area this evening. Showers will expand in coverage tonight with the potential for moderate to heavy showers east of the Genesee Valley after midnight. Drier air will filter into the west behind the cold front but low level moisture will linger. Clouds will start to clear across the Niagara Frontier by daybreak Thursday. Rainfall amounts will vary across the forecast area today and tonight. Amounts will mainly average less than 0.10 inches, however far western NY and the north central NY will average 0.10-0.25 inches today. Rainfall amounts will average 0.25-0.50 inches tonight, however any thunderstorms could produce amounts of up to an inch, mainly near Lake Erie and north central NY. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... A sharp mid level trough will move from near the Ontario/Quebec border Thursday morning to eastern Quebec and northern New England by late Thursday night. An associated surface cold front will cross the region Thursday morning. Latest 00Z model guidance has slowed the eastward progression of the front by a few hours, which brings a little more rain into the forecast for Thursday morning. Expect showers to end in far Western NY around daybreak Thursday, with rain and possibly a few isolated thunderstorms lasting through the morning for areas east and southeast of Lake Ontario before ending in the afternoon. A notable mid level dry slot will quickly follow the surface cold front, allowing for sunshine to return later in the day from northwest to southeast. Thursday night through Friday the eastern Great Lakes will be in a squeeze play between an evolving mid level low over northern New England and the Canadian Maritimes, and another closed low over the south central US. Between these two large systems, a narrow ridge of high pressure surface and aloft will build over the Great Lakes and support dry weather for our region. Temperatures will continue to run a little above average Thursday through Friday, with highs in the low to mid 70s for lower elevations and upper 60s for higher terrain. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... A complex pattern will evolve over the eastern US Friday night through the weekend. A mid level low over the Canadian Maritimes will move slowly southeast and into the North Atlantic Friday night through Saturday. Meanwhile, another large mid level closed low over the south central US will interact with the remnants of Helene Friday through Friday night, with a classic Fujiwhara interaction as the remnants of Helene first move in a cyclonic loop around the mid latitude closed low, and then eventually become absorbed into the closed low by Saturday over the Tennessee Valley. The vast majority of the greater impacts with the closed low and remnants of Helene will remain well southwest of our area across the Ohio Valley. Expect an extensive shield of mid/high clouds to stream northward into the eastern Great Lakes later Friday through the weekend as the upper level outflow of Helene`s remnants spread northward. Latest model guidance suggests the northern extent of light showers wrapping around the system may clip the western Southern Tier later Friday night through Saturday, with mainly dry weather elsewhere. Sunday through Monday, model and ensemble guidance show the mid level low containing the remnants of Helene moving east across the Ohio Valley to the Mid Atlantic states. This track would keep the majority of the rain south of our region, but it would not take much of a northward shift to bring higher rain chances to our area and this will need to be monitored through the coming days. Tuesday, a strong mid level trough and associated cold front is forecast to dig southeast across the Great Lakes, bringing an increasing chance of showers. The airmass is quite cool behind this cold front, with a trend towards below average temperatures for at least a few days starting around the middle of next week. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Low pressure will move northwest of the region today. Showers will move across the Lake Ontario region including north central NY this morning. Drier air will enter western NY decreasing the chance for showers through mid-morning. A warm front is in vicinity of northwest Pennsylvania which may result in a few showers developing across far western NY this morning. A southeast flow has resulted in mainly VFR conditions across the lower elevations with the exception of any showers or thunderstorms this morning. Low clouds/fog will hang onto the hill tops across the region and result in sub-VFR, mainly IFR conditions at KJHW/KOLE. Flight conditions do not change much through the day with MVFR/low end VFR across most of the TAF sites and IFR at KJHW. Showers and a few thunderstorms will likely develop this afternoon. These may result in brief periods of IFR at the TAF sites. A cold front will move across the region this evening. Heavier showers and a few thunderstorms will move through the region. MVFR/IFR conditions will linger into Thursday morning. Outlook... Thursday...MVFR east of Lake Ontario with a chance of showers. Becoming mainly VFR elsewhere. Friday through Sunday...Mainly VFR. Local IFR in valley fog across the Southern Tier possible overnight into the morning. && .MARINE... A moderate pressure gradient will remain in place over the eastern Great Lakes today through tonight between persistent high pressure over the Canadian Maritimes and low pressure moving through the central Great Lakes. This will maintain moderate southeasterly flow today, with the strongest winds on the east half of Lake Ontario today. The southeast wind direction will continue to push the greater wave action into Canadian waters, but the offshore winds will become strong enough to require a Small Craft advisory for the eastern ends of Lake Ontario and Lake Erie. Winds will gradually become southwest and then west tonight through Thursday as a trough crosses the eastern Great Lakes from west to east, with wind speeds decreasing with the passage of the trough. Northeast flow will then pick up Friday, possibly requiring small craft headlines on Lake Erie and western Lake Ontario. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...Small Craft Advisory until 2 AM EDT Thursday for LOZ045. && $$ SYNOPSIS...RSH NEAR TERM...HSK SHORT TERM...Hitchcock LONG TERM...Hitchcock AVIATION...HSK MARINE...Apffel/Hitchcock/HSK