571 FXUS61 KBUF 160228 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1028 PM EDT Sat Oct 15 2022 .SYNOPSIS... Surface high pressure will build in tonight with dry conditions and seasonable temperatures to round out the weekend. A deep trough of low pressure will then dig across the Great Lakes and Northeast bringing with it much colder weather along with some rain showers that may mix with some wet snow at times across the higher terrain. && .NEAR TERM /THROUGH SUNDAY/... Weak high pressure and drier air over the Ohio Valley will build northeastward across our area overnight. While our airmass will be cool enough to support a lake response...background synoptic moisture is rather unimpressive and capping inversion heights are fairly low (only about 6kft or so). Consequently...any such response should be limited to just some clouds northeast of the lakes...with any shower activity appearing unlikely at this time. Otherwise...we can expect lows ranging from the mid/upper 30s across interior portions of the Southern Tier/North Country to the lower 40s elsewhere. Sunday...sfc high pressure will provide a largely quiet dry day with temps peaking in the upper 50s across the higher terrain to the lower 60s along the lake plains. That said...a weak low will scurry by to our northwest which will then send its cold front east nearing the Lower Lakes by Sunday evening. This will set the stage for what looks like a very active period of weather as we head into the new work week. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... The pattern across North America will become highly amplified through the first half of next week with a large Omega Block across the western US and a deep longwave trough downstream across the east. This will set the stage for an extended period of below normal temperatures and unsettled weather. While it will be chilly, the airmass will only be marginally cold enough to support a chance of some wet snow mix across higher terrain through Tuesday night, with mainly rain for lower elevations. Lake effect rain may be heavy at times, especially Monday and Monday night northeast of Lake Erie. Looking at the details, Sunday night and Monday cold air will pour into the Great Lakes as a mid level circulation dives into the longwave trough. Most of the synoptic scale rain showers along the advancing cold front will focus over the eastern Lake Ontario region very late Sunday night and Monday. 850MB temps will drop to around -3C on Monday over Lake Erie. Deep, strong instability over the lake will support the development of organized lake effect rain over and northeast of Lake Erie, with flow averaging 230 degrees in the boundary layer directing most of this into the Buffalo Northtowns or even Grand Island/Niagara County at times. The lake effect rain will continue northeast of Lake Erie into Monday night, with persistent southwest flow continuing to direct the more organized rain into the Buffalo Northtowns. Meanwhile over Lake Ontario, even more southerly component will direct most, if not all of the lake effect rain Monday and Monday night into Canada to the west of Jefferson County, with just a few light upslope showers across the higher terrain east of Lake Ontario. Precipitation type will stay all rain Sunday night through Monday evening. Later Monday night some wet snow may start to mix in across the higher terrain of the western Southern Tier and Tug Hill region. The southwest flow will keep the organized lake effect away from higher terrain areas however, so the chances for any measurable snow will stay very low through Monday night. Tuesday and Tuesday night the axis of the longwave trough will advance slowly east across the Great Lakes, bringing increased synoptic scale forcing and deep moisture with time from west to east. 850MB temps will remain close to -3C through the period, cold enough for a strong lake response but generally not cold enough for much in the way of snow except for some mix across the high terrain. Boundary layer flow will gradually veer from SW to WSW through the period, allowing the Lake Erie lake effect to move from the Buffalo area southward into the western Southern Tier initially close to Lake Erie, and then spreading inland by later Tuesday night. Lake Ontario lake effect will still be mainly west of Jefferson County in Canada through Tuesday and Tuesday evening, before approaching the Thousand Islands region by late Tuesday night as boundary layer flow starts to veer from SSW to SW over the east end of Lake Ontario. Precipitation type will stay rain at lower elevations Tuesday and Tuesday night, with some wet snow mix possible across the high terrain Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A closed upper level trough will remain over our region to start the period, with its center very close to lake Ontario at periods start. While the core of this upper level low begins to lift northward Wednesday, additional shortwave troughs rounding the upper level low will replenish the cool air and moisture over the Lakes through at least Thursday night if not Friday. Bands of primarily lake effect rain, and some higher elevation wet snow will continue to oscillate east of the Lakes Wednesday and into Thursday, before lifting northward towards Canada and diminishing late Thursday and into Thursday Night. The mean flow becomes zonal Friday, and even tilts towards some ridging Saturday allowing for a warmer airmass to push into the region next Saturday. Below normal temperatures through a good portion of the forecast period will become around to even above normal on Saturday. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... VFR conditions with notably lower wind speeds will be in place overnight through Sunday evening. The only winds worth mentioning at this point will be some gusts to 25 knots or so at KBUF and KIAG Sunday afternoon. Deepening cold air and an increase in low level moisture in the wake of a cold front will combine to allow for lake induced MVFR cloud cover east of both lakes later Sunday night. The lower cigs will likely be accompanied by some rain showers. Outlook... Monday through Wednesday...Scattered to numerous rain showers along with areas of lake enhancement/MVFR. The rain will mix with wet snow across the higher terrain both Monday and Tuesday nights. Thursday...MVFR within lake effect northeast of the lakes. VFR at all other terminals. && .MARINE... High pressure centered over the Upper Ohio valley late this evening has nosed far enough to the north to weaken the associated sfc pressure gradient over Lake Erie...and with nocturnal decoupling... will cancel small craft advisories for Lake Erie...BUF Harbor and the Upper IAG River...and the western half of Lk Ontario. The winds on the east end of Lk Ontario are still high enough with lagging high waves to keep those SCAs intact for much of the night. Moderate southerlies throughout the Lower Great Lakes Sunday will freshen a bit on Lake Erie while briefly veering to the southwest. While choppy conditions will be found on parts of Lake Erie on Sunday...especially well offshore...conditions should remain below SCA criteria. Winds will veer to the west southwest on both lakes Sunday night in the wake of a cold frontal passage. Small craft advisories may be needed on Lake Erie by Monday morning. A stacked...nearly stationary storm system centered over southern Ontario on Monday will generate fresh to strong southwesterlies... especially on Lake Erie. High end SCA's will be needed at that time for Lake Erie...while the roughest waters on Lake Ontario may be confined to international waters. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...Small Craft Advisory until 5 AM EDT Sunday for LOZ044-045. && $$ SYNOPSIS...AR NEAR TERM...AR SHORT TERM...Hitchcock LONG TERM...Thomas AVIATION...RSH MARINE...RSH