182 FXUS61 KBUF 110001 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 701 PM EST Sun Nov 10 2019 .SYNOPSIS... Some light rain is expected this evening as moisture streams into the area ahead of the next system. A cold front will then move slowly south across the area later tonight, allowing the light rain to change to light snow. Periods of light snow will continue through Monday morning before increasing in intensity during the afternoon. Widespread accumulating snow will then continue through Monday night, with a wintry mix possible near the Pennsylvania state line at times. The snow will taper off by early Tuesday, and will be followed by very cold temperatures and some limited lake effect snow southeast of the lakes through Wednesday. && .NEAR TERM /THROUGH MONDAY NIGHT/... Abundant cloud cover and meager rainfall with negligible lift continues this evening while a strong W--->E oriented jet moves across Southern Ontario. This will help develop the upstream longwave trough that should produce our first widespread plowable snow event on Monday. In the meantime, expect very light rainfall and perhaps a little snow toward morning with minimal impact through daybreak. On Monday, a stalling frontal boundary will become the source for increasing low level convergent flow while the airmass cools throughout much of the atmospheric column. For MOST of the area (except the Southern Tier) initially, warm advection aloft will result in light rain-->snow for the morning with continued minimal impacts, but this will change during the afternoon with stronger synoptic lift from the jet entrance region in concert with the upstream deepening trough, resulting in continued low level frontogenesis accompanied by an eventual surface low over the Ohio Valley and/or Western PA by Monday evening. The result will be accumulating snow (~1"/hr) spreading across MOST of the region into the afternoon, with the highest impact from accumulating snow lasting well into Monday evening. The exception may be the extreme Southern Tier where profiles may be warm enough for some sleet or freezing rain, primarily near the PA border. The steady snow will then taper off quickly from west to east late Monday night through early morning Tuesday. Initially, the airmass will not cold enough in the boundary layer to support lake enhancement with the favorable dendritic crystal growth zone residing way up at around 15K feet. This will change for a few hours right at the tail end of the event sometime Monday night. This may add some added snowfall along the south shore of Lake Ontario from Monroe County eastward to Wayne County. A Winter Storm Watch remains in effect with storm total accumulations of 6-9 inches, with some local amounts of 10+ inches where mesoscale banding and/or lake enhancement develops. The bulk of this accumulation will be from late Monday afternoon through the pre-dawn hours of Tuesday, when travel conditions will be worst. Temperatures will trend downward through the period, falling from the 40s this evening to the lower 30s by Monday morning. Temperatures will hold steady in the lower 30s most of Monday before falling into the 20s by late afternoon or early evening, then falling through the 20s Monday night. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... By Tuesday morning the steady synoptic snows will have ended across far western New York...and will be in the process of winding down from the Finger Lakes eastward...with these likely coming to an end there by mid-morning as the responsible area of low pressure exits out across New England. In its wake another surge of much colder air will pour across the area Tuesday and Tuesday night...with consensus 850 mb temperatures falling to between -16C and -19C. This will result in unseasonably cold temperatures prevailing right through this period...with highs both Tuesday and Wednesday failing to get above the lower to mid 20s...and lows Tuesday and Wednesday nights ranging in the teens south of Lake Ontario...and the single digits across the North Country. While such a cold airmass and the prevailing northwesterly flow will easily be sufficient to promote a lake response southeast of the lakes Tuesday and Tuesday night...at the same time the rather dry nature of the airmass will help to keep this response more limited in nature than what might otherwise be expected at first glance. Off Lake Erie...the northwesterly flow and resultant favorable orographic enhancement will support fairly high probabilities for snow showers through Tuesday night. This said...the core of the upstream connection to Lake Huron still appears likely to remain to our west over northwestern PA/northeastern Ohio...and this in tandem with the short fetch across Lake Erie should result in generally light snow...with only minor amounts of a few inches falling every 12 hours within the most persistent snow showers. Meanwhile off Lake Ontario...more of a west-northwesterly flow would tend to direct the lake effect snow showers across a corridor extending from eastern Monroe to western Oswego counties through Tuesday...before subtle veering of the flow potentially shunts this activity a little further southwestward toward Rochester (and out of all except southern Oswego county) Tuesday night. Through Tuesday the rather dry nature of the cold airmass and the lack of an upstream connection should keep the activity on the light side...with only a few inches of accumulation expected within the most persistent snow showers. Tuesday night this could change for at least a time as an upstream connection to Georgian Bay may develop...which if realized could lead to some advisory-type accumulations somewhere in the Monroe-Northern Cayuga county corridor. The above said...such a connection is still far from a lock at this point in time...and should this not occur any accums would likely remain on the minor side through Tuesday night. Needless to say...we will continue to monitor this potential as we get closer to this event...and it comes into the window of higher resolution guidance. On Wednesday strong surface-based ridging will quickly build into our region...with attendant drier air/crashing inversion heights and a weakening of the low level flow causing the lake effect to devolve into some scattered leftover snow showers southeast of the lakes Wednesday morning. As the ridge axis departs off to our east...the increasingly southerly and sheared nature of the flow on its backside will then result in the remnant activity lifting northward to areas northeast of the lakes and quickly falling apart between Wednesday afternoon and evening. Outside of the above...mainly dry weather should prevail through at least the first half of Wednesday night...with just a lower-end chance of snow showers reaching far western New York later Wednesday night out ahead of an approaching mid level trough/associated weak warm front. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Thursday and Thursday night the aforementioned weak mid level trough and its attendant surface trough will cross our region. While weak...this system should still help to generate some scattered light rain and snow showers as it crosses our region...with some lake enhancement possible northeast of the lakes given still cold- enough temperatures aloft. Otherwise...ongoing warm advection should help Thursday's highs to recover into the lower to mid 30s east of Lake Ontario...and the mid to upper 30s elsewhere. Yet another mid-level trough will then pass by to our north on Friday...with its attendant cold front pushing southward and across our region. While the portion of this boundary crossing our region will be starved for both moisture and upper level support and therefore only capable of generating some widely separated rain and snow showers...some modest lake enhancement will remain possible east of the lakes given still-cold enough temperatures aloft. Following the passage of this system...one last shot of colder but also rather dry air should then follow for Friday night...with the dry nature of the colder airmass helping to confine any lake response to some scattered snow showers southeast of the lakes. Looking ahead to next weekend...strong high pressure looks to quickly build in and crest across our region later Friday night and Saturday...before sliding eastward and off the New England coast on Sunday. Associated drier air and subsidence should bring a return to fair dry weather by Saturday...with this then continuing through the rest of the weekend. Meanwhile well below normal temperatures will continue through Saturday...before warm advection on the backside of the high marks the beginning of a warming trend by Sunday...when highs should recover into the upper 30s to mid 40s areawide. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... A cold front will move slowly south across the area tonight. IFR CIGS will become more widespread as north and northeast upslope flow develops and low level moisture becomes trapped beneath a steepening frontal inversion. Light rain showers will continue at times tonight, mixing with some wet snow late tonight. MVFR VSBY will become common in the light precipitation, with some IFR possible with the change to snow. The light mix will change to all snow Monday morning, then increase in intensity later in the afternoon through Monday night. Expect widespread IFR CIGS/VSBY during this time frame. There may be a period of enhanced snowfall rates for several hours during the first half of Monday night, which may bring VSBY down near airfield minimums at all the TAF sites. Outlook... Tuesday and Wednesday...VFR/MVFR. A chance of snow showers. Localized lake effect snow and IFR southeast of the lakes. Thursday...MVFR/IFR with a chance of snow showers, especially east of the lakes. Friday...VFR. && .MARINE... Moderate west winds will continue to produce Small Craft Advisory conditions over the east end of Lake Ontario through early evening. There will then be a temporary lull in winds tonight as a cold front slowly moves south across the eastern Great Lakes. Monday, northeast winds will increase in the wake of the cold front, bringing another round of Small Craft Advisory conditions to the south shore of Lake Ontario and Lake Erie. These moderate northeast winds will continue through Monday evening before becoming more northwest by Tuesday. && .CLIMATE... A frigid airmass will pass over the region next week. The shot of sub arctic air will support widespread lake snows and will could result in some record temperatures. Below are the record low maximum temperature and record low minimum temperature for our three climate sites of Buffalo, Rochester and Watertown. City.......Record Low Maximum (Year)...Record Low Minimum (Year) Monday November 11 Buffalo..........27F (1933)............19F (2017) Rochester........29F (1933)............20F (1957) Watertown........31F (2017)............12F (2017) Tuesday November 12 Buffalo..........31F (1983)............22F (1921) Rochester........32F (1983)............21F (1983) Watertown........32F (2013)............15F (1997) Wednesday November 13 Buffalo..........24F (1911)............16F (1986) Rochester........23F (1911)............17F (2013) Watertown........24F (1983)............11F (1997) && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Storm Watch from Monday afternoon through Tuesday morning for NYZ006>008. Winter Storm Watch from Monday morning through Tuesday morning for NYZ003>005-013-014. Winter Storm Watch from Monday morning through late Monday night for NYZ001-002-010>012-085. Winter Storm Watch from Monday morning through late Monday night for NYZ019>021. MARINE...Small Craft Advisory from 10 AM Monday to 10 AM EST Tuesday for LEZ040-041. Small Craft Advisory from 10 AM Monday to 10 AM EST Wednesday for LOZ043-044. Small Craft Advisory from 10 AM Monday to 1 AM EST Wednesday for LOZ042. Small Craft Advisory until 10 PM EST this evening for LOZ044-045. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock/Zaff SHORT TERM...JJR LONG TERM...JJR AVIATION...Hitchcock/Thomas/Zaff MARINE...Hitchcock/Zaff CLIMATE...Thomas/RSH