Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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857 FXUS61 KBUF 090224 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1024 PM EDT Wed May 8 2024 .SYNOPSIS... Scattered light showers will wind down through the early overnight hours east of Lake Ontario as low pressure pulls east into New England. Otherwise, high pressure will nose in from the northwest providing mainly dry weather tonight through at least the first half of Thursday, before shower chances slowly increase toward the Pennsylvania state line Thursday afternoon. This will be the start of another fairly unsettled weather pattern that will impact the region for the end of the work week into this weekend as a series of low pressure systems cross the region. && .NEAR TERM /THROUGH THURSDAY NIGHT/... Dry weather is found from the Finger Lakes westward late this evening. However, a few scattered light showers will linger east of Lake Ontario through the early overnight hours on the back side of low pressure as it exits east into New England. Otherwise, surface high pressure will nose southeast across the area in the wake of the cold frontal passage. This will provide rain-free conditions across all of western and northcentral NY for the second half of tonight, however plenty of lingering low level moisture will ensure plenty of clouds hang around through the remainder of the overnight. Lows will range through the 40s. Latest trend in guidance continues with the overall slower and further south solution with regards to a convectively augmented wave of low pressure on Thursday. Meanwhile, weak surface high pressure to the northwest remains nosed in across the region providing a stabilizing, but cool northeasterly low level flow. With this in mind, still appears it will remain rain-free through at least the first half of Thursday with slowly increasing chances for showers across areas south of the NYS Thruway, especially toward the NY/PA state line later in the day. Conditions will once again become increasingly unsettled with some showers likely to move across the area Thursday night, bringing some additional mainly light rainfall amounts. The stable/cool northeasterly flow will mean there will be little to no risk for thunderstorms, but will also guarantee cooler temperatures on Thursday that will actually be a bit below average with highs ranging from the mid 50s to lower 60s. A few mid 60s will be possible toward the Saint Lawrence Valley where more in the way of sunshine is expected. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... High confidence for BELOW normal temperatures during this period... particularly by day when the mercury is only forecast to reach into the upper 50s to near 60. That will be a solid 5 to 8 degrees below mid May normals. Meanwhile...it will generally be unsettled with perturbations in the mean longwave trough supporting some showers and thunderstorms. As for the details... A shortwave will drive across the Lower Great Lakes on Friday...as a wavy sfc frontal boundary will stretch across the Tennessee valley to the Mid Atlantic region. The resulting DPVA and minimal height falls will couple with a deep cyclonic flow and wealth of moisture to warrant chc to likely pops over the far western counties and cat pops over the Finger Lakes region and portions of the Srn Tier where a change will be made in the wording from showers to rain. There could be several hours of widespread/steady rain for that area. Finally...H5 temps of -20c will enhance the instability aloft...the mid levels will be stable enough to preclude the risk for thunder. A weak shortwave ridge will scoot across the forecast area Friday night. While spotty showers may persist east of Lake Ontario...this scenario will bring an end to the pcpn over the western counties. Saturday...another robust shortwave will drop through the longwave trough and pass just to the west and south of our forecast area... along with a loosely organized sfc reflection. Unlike the previous shortwave passage the day before (Friday)...this will focus the associated forcing over the western counties. Will raise pops for the Srn Tier to categorical...but being largely convective (H5 ~ -24c)...will maintain the wording of showers. The mid levels will be more unstable as well...so will add slgt/chc wording for tstorms for the western counties. Given the mean trough axis will cross the region Saturday night...will maintain at least chc pops for showers. A nominal 70kt H5 jetlet will dig into the base of the aforementioned longwave trough over the region on Sunday and encourage it to close off across New England. The slow exit of the trough will keep at least scattered showers in place...particularly over the Finger Lakes and Eastern Lake Ontario regions. Low single digit H85 temps will keep the cool weather in place with the mercury struggling to make it out of the 50s. && .LONG TERM /MONDAY THROUGH TUESDAY/... A closed low and associated deep longwave trough centered in the vcnty of Hudson Bay at the start of this period will rotate out across Quebec during the course of the week. This will result in height rises across the Lower Great Lakes that will lead to temperatures finally returning to ABOVE normal levels. While this general pattern will favor fair weather for the majority of the period...another shortwave will push a cold front through the region later Monday and Monday night. This will result in scattered showers and a minimal risk for thunderstorms. Dry weather should prevail with a passing shortwave ridge Tuesday and Tuesday night...then energy in the southern stream will help to support a storm system that should pass to our south on Wednesday. Being on the northern fringe of this system...there will be the potential for showers. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... MVFR/IFR CIGS expected tonight for areas east of Lake Ontario (KART), as well as a few scattered light showers lingering through the early overnight hours. VFR flight conditions for areas south of Lake Ontario (KBUF/KIAG/KROC/KJHW) late this evening before increasing low level moisture and a moist north/northeast upslope flow in the wake of a cold fropa bring a period of mainly MVFR CIGS for much of the second half of tonight, with IFR CIGS interior Southern Tier. Weak high pressure will nose in from the northwest Thursday, thus with low level drier air working in, expect areas from the Niagara Frontier (KBUF/KIAG) east and northeast to KROC and KART to be in the low VFR (3-5kft) CIG range by late tonight/early Thursday morning, eventually scattering out through the morning hours leaving behind mid level decks through the afternoon. Expect improvement to low VFR at KJHW during the first part of Thursday morning. Widespread VFR is then expected for Thursday afternoon, although there will be the chance for a few scattered showers and MVFR CIGS to return across the western Southern Tier (KJHW) late in the TAF period. Outlook... Thursday night and Friday...Mainly MVFR. Showers likely and MVFR stratus. Saturday through Monday...VFR/MVFR. A chance of showers. && .MARINE... Winds and wave action will fall below SCA criteria, thus will allow Small Craft Advisories on Lake Erie to expire late this evening. However, some light chop will remain on both Lakes as winds shift to a mainly light northeasterly flow overnight. This northeasterly flow will strengthen some on Thursday and Thursday night. This will result in choppy conditions along the south shores of both Lakes, especially on Lake Erie where marginal Small Craft conditions will develop on Thursday, with a better chance of seeing solid Small Craft conditions later Thursday into Thursday night on Lake Erie as winds freshen a bit more. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...JM NEAR TERM...JM SHORT TERM...RSH LONG TERM...RSH AVIATION...JM MARINE...JM