Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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931 FXUS61 KBUF 240457 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1257 AM EDT Tue Sep 24 2024 .SYNOPSIS... As a mid-level disturbance departs the region, a few rain showers will linger through the nighttime hours. An approaching and crossing warm front will bring a round of widespread rain showers Tuesday afternoon and night. A cold front may keep some showers into Wednesday. Temperatures will trend above normal through mid week. && .NEAR TERM /THROUGH TODAY/... Weak surface low pressure over Lake Erie will degrade into an inverted surface trough tonight, while an associated surface boundary remains situated near or just west of BUF/IAG. Cloud cover will linger through the night, with a few mainly light showers with overall weak forcing. The majority of the scattered showers will focus along a convergence zone from Allegany County northward to areas just west of the Genesee River. Low temperatures tonight will range from the lower 50s on the Tug Hill, to mid 50s to lower 60s across the lake plains of Western NY with persistent southeast downslope flow. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... A deep longwave trough will advance from the Mississippi Valley Tuesday towards the Great Lakes and Ohio Valley by Wednesday. Models are in decent agreement that the large-scale trough will evolve separate northern and southern stream components, with a closed cutoff low developing near the Ohio-Mississippi River confluence, and a negative tilt trough and/or closed low develop across eastern Ontario into Quebec by Thursday morning. Tuesday morning will be mainly dry, with a few isolated showers at most across the region. However, during the afternoon, a shortwave embedded in the developing northern portion of the large scale trough will cross the Great Lakes and surface low pressure will lift into lower Michigan by Tuesday night. With lift supported by the shortwave and a surface warm front, and strengthening southwest flow bringing precipitable water values in the 1.5 to 1.6 inch range by Tuesday evening, widespread showers appear to be a good bet later Tuesday and Tuesday night. On Wednesday, as the Michigan surface low lifts into Quebec, the system cold front will be dragged across the eastern Lakes and reside in the eastern portions of the forecast area by afternoon. A weak wave along the boundary may keep higher PoPs going here, while drier air tries to build in behind the boundary in western New York, leading to a drier forecast. This drier air becomes more widespread across the region by Thursday as the northern shortwave trough axis shifts more towards New England, although a few showers may continue in the eastern Lake Ontario region, closest to sufficient moisture and forcing. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Dry weather appears likely through at least the Thursday night through Saturday period. A ridge appears likely to set up in the western New York area between upper level low pressure across the Canadian Maritimes, and another upper low centered somewhere in or near the Lower Mississippi Valley. The only fly in the ointment could be related to this week`s potential Gulf tropical activity, as a small bit of moisture from what would be remnants at that point could sneak into areas south and west of Buffalo on Saturday, producing some showers. Uncertainty regarding the Mississippi Valley upper low increases thereafter according to model cluster analysis, with the slight majority of scenarios keeping the low center more or less in place, while others try to open the system and eject it to the northeast. This latter scenario would lead to a wetter forecast for western New York by the end of the forecast period. Given this uncertainty, the NBM idea of some low PoPs across areas generally near and west of I- 390 during the Sunday/Monday period is a good one. Temperatures will continue run a little above normal overall. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Scattered showers will continue through the early morning hours, especially just west of the Genesee Valley. CIGS across Western NY will continue to run mainly MVFR for lower elevations and IFR across the higher terrain of the western Southern Tier through the morning hours. Meanwhile, areas east of Lake Ontario will stay dry with VFR CIGS. Surface low pressure and a strong upper level system will move from near Lake Michigan this morning northeast across the central and eastern Great Lakes later today through tonight. A broad area of ascent ahead of this system will bring another round of widespread rain showers, entering Western NY midday to mid afternoon, then spreading east across the rest of the area later this afternoon through tonight. Pockets of moderate rain may bring a few periods of lower VSBY. Expect widespread MVFR/IFR CIGS across Western NY this afternoon, spreading east across the remainder of the area tonight. IFR will be favored across higher elevations. S/SE downslope flow will try to hold the CIGS higher across the lake plains including most of the terminals. MVFR CIGS are still likely, but the downslope flow may help to keep IFR at bay this afternoon through tonight. Outlook... Wednesday...MVFR/IFR with showers likely. A few widely scattered thunderstorms possible. Thursday...MVFR east of Lake Ontario with a chance of showers. Becoming mainly VFR elsewhere. Friday through Saturday...Mainly VFR. Local IFR in valley fog across the Southern Tier each overnight and morning. && .MARINE... Southeast wind will continue through tonight, approaching 20 knots over the offshore waters of eastern Lake Ontario. Waves of 3 to 5 feet can be expected here along the Canadian border waters. South to southeast wind will continue into Wednesday as a cold front stalls over the lower Great Lakes. Once this front passes on Wednesday, winds will veer through southwest and to a westerly direction during the Wednesday night/Thursday period. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock SHORT TERM...HSK LONG TERM...HSK AVIATION...Hitchcock MARINE...Hitchcock