052 FXUS61 KBUF 292121 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 521 PM EDT Wed Apr 29 2020 .SYNOPSIS... A warm front will usher in a notably milder airmass along with a few showers and gusty winds through this evening. A large storm system stalled over Lower Michigan through Thursday will slowly cross our region Thursday night and Friday while generating fairly widespread showers and possibly some thunderstorms in the process. High pressure will then build across the region and provide dry weather for Saturday. && .NEAR TERM /THROUGH THURSDAY NIGHT/... The remainder of the evening will be breezy and mainly dry, however a brief shower or sprinkle cannot be ruled out as narrow bands of showers lifting ahead of the low dry up as they encounter dry air mass across our region. It will remain warm, with evening readings remaining in the 60s over the Niagara Frontier and in the 50s elsewhere, except over the Tug Hill where temps will fall into the upper 40s. Stacked low pressure currently over west central Michigan near Muskegon will only make it east of Detroit by this time on Thursday, then gradually weaken as it slowly moves eastward across Western New York Thursday night. Model guidance has continued a slowing trend, with steady rain not expected to reach far Western New York until late tonight, before moving across the area Thursday into Thursday evening. This system will produce gusty winds across the region, especially downslope locations. Southeasterly winds of 45-55 knots at 925mb (strongest east of Lake Ontario) are effectively cross-barrier for the Chautauqua Ridge, Tug Hill, and Western Adirondacks. The slower onset timing for steady rain also increases confidence in wind gusts to 50 mph since winds tend to mix better before the rain starts. The gusty winds will continue from the Genesee Valley eastward on Thursday before tapering off by Thursday evening. Wind advisories in place for downslope regions, with gusts of 35 to 45 mph expected elsewhere. This system will also produce a soaking rainfall, with a small risk of flooding across upper portions of the Genesee Valley, Western Finger Lakes, and Black River Valley. Modest precipitable water values of 1-1.25 inches, however the LLJ jet axis ahead of an occluded frontal boundary will be very slow moving which could potentially support training storms. Most model guidance keeps the heavier rains to our south and east, and because of this did not issue a Flood Watch. However, if this does trend into our area there would be a risk of localized lowland flooding, and/or river flooding. This thinking is in line with the WPC Excessive Rainfall Outlook which has our region on the fringe of a slight risk. Otherwise, there's a risk of some embedded thunderstorms Thursday into Thursday evening. SB CAPE is minimal, but with a moist environment and some elevated instability, thunderstorms cannot be ruled out. Steady rains will end from W-E Thursday evening, following the progression of the system. Temperatures will remain on the warm side tonight and into Thursday morning, then will drop considerably with the low and associated front Thursday night. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... The low pressure system that impacted the weather that occurred midweek, will become very close to vertically stacked by Friday. Additionally, the vertically stacked system will gradually take its time to ride up the mid-Atlantic and New England coast Friday and Friday night, which will keep much of the eastern Great Lakes under moist cyclonic flow, producing frequent showers and light rain across the region throughout the Friday and Friday night time frame. Temperatures on Friday will be on the cooler side of average as the region will remain under northwesterly flow. In the wake of the low pressure system, a ridge of high pressure will ride across the eastern Great Lakes late Friday night for Saturday. As the high invades Friday night, its associated dry air will act to erode away the showers, leaving Saturday and a vast majority of Saturday night dry. Daytime highs on Saturday will remain around average for this time of year. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... By Sunday, the next shortwave will be digging across the upper Great Lakes. It will then move over the lower Great Lakes Sunday night and Monday, before moving across New England Monday night and off the New England coast by Tuesday. At the surface, low pressure will track south of James Bay into Southern Quebec on Sunday, while dragging its' attendant cold front into the central Great Lakes. A secondary wave of low pressure may develop across the Ohio Valley along the front as additional shortwave energy moves into the longwave trough. This will bring an increasing chance for a few light showers as the day progresses Sunday, especially across the western half of the forecast area. Temperatures will reach a relative peak again Sunday as a brief bubble of warming ahead of the front moves into the eastern Great Lakes. Highs will reach well into the 60s away from the lakeshores. The cold front will then cross the region Sunday night, allowing the chances for showers to continue. Yet another much cooler airmass will then move back into the region Monday through the middle of next week. Lingering wraparound moisture within a cool cyclonic flow aloft will keep at least the risk for some scattered showers going across the area through Monday, with some wet flakes possibly mixing in across the higher terrain Monday night. As was eluded to above, temperatures will again trend well below normal, with highs struggling to reach 50F at lower elevations Tuesday, with low to mid 40s for higher terrain. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... Mainly VFR conditions through late tonight, but winds will be gusty for much of the TAF cycle. At our terminals, gusts of 25 to 35 knots can be expected through tonight. There will also be a 55-65kt low level jet move through tonight...and this will pose the risk for some low level wind shear. More widespread showers will slowly spread from W-E into the area late tonight through Thursday morning. These will be moderate to heavy at times, while also lowering cigs into the MVFR flight category. Outlook... Thursday night through Friday...Areas of IFR/MVFR with occasional showers. Saturday...Mainly VFR. Sunday and Monday...VFR/MVFR. A chance of showers. && .MARINE... A storm system will remain stalled across lower Michigan, which will establish a brisk southeasterly flow. This will direct the highest waves and choppiest conditions into Canadian waters, however it will be windy enough to justify small craft headlines across eastern portions of Lake Erie and Ontario tonight and into Thursday. Winds will diminish from west to east on Thursday following the progression of a slow moving occluded front. Winds will diminish Friday as the increasingly diffuse surface low moves across the waters. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Wind Advisory until 11 PM EDT Thursday for NYZ007-008. Wind Advisory until 6 AM EDT Thursday for NYZ019-085. MARINE...Small Craft Advisory until 6 AM EDT Thursday for LEZ040-041. Small Craft Advisory until 2 PM EDT Thursday for LOZ045. Small Craft Advisory until 11 AM EDT Thursday for LOZ044. && $$ SYNOPSIS...Apffel NEAR TERM...Apffel/JLA SHORT TERM...EAJ LONG TERM...Hitchcock/JM AVIATION...Apffel/JLA MARINE...Apffel