Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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838 FXUS61 KBUF 251828 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 228 PM EDT Tue Jun 25 2024 .SYNOPSIS... Warm and humid conditions today will last into Wednesday, along with increasing chances of showers and some thunderstorms, especially on Wednesday. Cooler and less humid conditions expected Thursday and Friday. Active weather returns Saturday as a cold front crosses the region. && .NEAR TERM /THROUGH WEDNESDAY/... Surface ridge will continue to exit off to the east through this afternoon. Strengthening southerly flow bringing wind gusts up to 40 mph this afternoon across far western New York. Earlier MCS has nearly fall apart with some remnant showers moving across southern Ontario/Lake Ontario. Some of this shower activity could brush the eastern Lake Ontario region later this afternoon. A weak cold front drops south into the region tonight with additional chances for some showers or a isolated thunderstorm. The best chances will again be found again across the North Country closer to the support from the upper-level jet. Overnight low temperatures should fall back into the 60s. Wednesday should start off relatively quietly as the frontal boundary working south overnight stalls out over the region. This boundary waver back northward during the day as a frontal wave moves north along it from the Ohio Valley. The western Southern Tier will have the best chance to emerge into the warm sector, with the potential that the warm sector lifts as far north as the I-90 corridor by afternoon. The coverage of thunderstorms and the potential for severe weather will depend greatly on the position of the frontal boundary with the degree of instability high depended upon where the warm sector is located. Therefore, CAPE values remain in question, but sufficient shear looks to be present, especially along the Southern Tier, which lines up with the Marginal Risk for severe storms maintained by the latest SPC Day 2 Convective Outlook. Precipitable water values surge to near 1.5 inches bringing at least some threat for heavy rainfall. The greatest risk of this will be across the western Southern Tier which will lie closer to the track of the passing frontal wave. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... On Wednesday low pressure over northern Quebec and Labrador will gradually pivot its trailing cold front southeastward across our area. During the morning and very early afternoon hours...this feature should be largely starved for much in the way of support...and thus will probably only produce some scattered showers and perhaps a couple of thunderstorms as it makes its way roughly to/ just south of the I-90 corridor. After that time...a wave of low pressure will ripple northeastward along the boundary and slow its southward progress through the balance of the day...while also providing a notable uptick in moisture and large-scale ascent. This should translate into showers and some storms becoming more numerous to widespread across the Southern Tier and interior of the Finger Lakes Region during the afternoon and early evening hours...while more scattered pcpn should be found further north along the northern periphery of the passing wave. Given continued uncertainty in the timing/positioning of the frontal boundary...the amount of available instability during this more active portion of Wednesday remains rather questionable at this time. This being said...if sufficient instability is realized can see at least a lower-end risk for an isolated stronger storm or two across the Southern Tier given the presence of sufficient shear...which lines up well with the Marginal Risk for severe storms advertised by SPC in the latest Day 2 Convective Outlook. With PWATs also temporarily surging to around 1.5 inches...there will also be at least some threat for heavy rainfall with any storms...with this risk again greatest across the western Southern Tier which will lie closest to the track of the passing wave. With respect to temperatures...these should range from the mid 70s to lower 80s...with humid conditions out ahead of the front becoming somewhat less so following the passage of the boundary. Wednesday night a shortwave trough will slide across our region while escorting the initial wavy cold frontal boundary and any deeper moisture/attendant threat for heavier rain off to our south and east...resulting in a commensurate northwest-to-southeast decrease in pcpn potential. In its wake...a much weaker and moisture- starved secondary cold front will slide across our area later Wednesday night and early Thursday...while possibly bringing a few more widely scattered showers to the North Country and far eastern Finger Lakes. Yet another shortwave will then dive across Southern Ontario and Saint Lawrence Valley Thursday afternoon and evening... and this in tandem with some weak diurnally-driven instability could lead to a yet few more widely scattered showers across the North Country. Otherwise generally dry and uneventful weather will predominate across our region from the second half of Wednesday night through Thursday...though the influx of cooler air and developing upslope flow behind the passing fronts will probably lead to at least some lower clouds hanging around into Thursday morning. As for temps...the incoming cooler/drier airmass will bring about much more comfortable conditions for Wednesday night and Thursday... with lows Wednesday night generally between 55 and 60...and highs on Thursday mostly ranging from the upper 60s across the higher terrain to the lower 70s elsewhere. Expansive Canadian high pressure will then build directly across our area Thursday night...then will drift east into New England on Friday. This will provide us with fair dry weather to close out the work week. Excellent conditions for radiational cooling will allow lows to settle into the mid-upper 40s across the interior Southern Tier/North Country and to the lower-mid 50s elsewhere Thursday night...with a developing southerly return flow on the backside of the departing ridge then allowing highs to recover to the mid 70s across the North Country and the upper 70s-lower 80s elsewhere on Friday. && .LONG TERM /SATURDAY THROUGH TUESDAY/... A well defined shortwave trough will cross the Great Lakes Saturday, deepening an area of surface low pressure that will advance from the northern Great Lakes through southern Quebec Saturday. A deep southerly flow ahead of this trough will advance moisture northward, increasing PWATs to nearly 2 inches across the eastern Great Lakes region. Showers and thunderstorms are expected to form Saturday and continue through the evening hours of Saturday before a cold front crosses the region from west to east late. The timing of the cold front, cloud cover holding instability back to around 750 J/KG or less and poor mid level lapse rates under 6 C/KM are not favorable for strong to severe storms. However, 0-6 km bulk wind shear values 35 to 45 kts could aid in strength to the storm if any taller storms can develop. Behind the cold front a much drier airmass will settle upon the eastern Great Lakes. We`ll still have to contend with a few showers Sunday with the passage of the upper level trough, but drier air and eventually cooler airmass (mid single digit Celsius 850 hPa temperatures) will bring a cool night Sunday night with lows in the mid 40s to mid 50s. Fair weather Monday, with comfortable dewpoints in the 40s and 50s with high pressure nearby. Tuesday a return southerly flow along with the approach of a shortwave from the west may trigger a few showers or thunderstorms. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Mainly VFR expected to remain across all area terminals into this evening. South to southwest winds of 30 to 35 knots at KBUF and KIAG and possibly KROC will diminish after 00Z. Tonight...a mix of VFR/MVFR Cigs will be found across most area terminals. Lower Cigs (IFR) may materialize across the S. Tier to include KJHW. Outlook... Wednesday...MVFR/VFR with a chance for showers most area terminals. Showers and a chance of thunderstorm across the Southern Tier. Thursday and Friday...Mainly VFR. Saturday...Localized restrictions with shower likely and a chance of thunderstorms. Sunday...Mainly VFR. && .MARINE... A south to southwest wind flow picks up across Lake Erie and the western end of Lake Ontario today. Waves will be offshore, but a period of Small Craft conditions will develop this afternoon into the evening. SCAs remain in effect for Lake Erie beginning at 16Z though 03Z this evening and for the Upper Niagara River until 00z. Winds will remain elevated on area the lower Great Lakes tonight producing light to moderate chop on both lakes. Lighter winds and wave action is expected Wednesday but there will be a better coverage of thunderstorms for Lake Erie. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020. Small Craft Advisory until 11 PM EDT this evening for LEZ040-041. && $$ SYNOPSIS...AR/TMA NEAR TERM...TMA SHORT TERM...JJR LONG TERM...Thomas AVIATION...AR/TMA MARINE...AR/TMA