240 FXUS61 KBGM 092309 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 609 PM EST Mon Dec 9 2019 .SYNOPSIS... Periods of rain and areas of fog through tonight with a low pressure system tracking through the Great lakes. Colder air will follow for Tuesday afternoon, bringing snow showers to central NY and a period of light snow to northeast PA. Cold weather and lake effect snow showers continue into Thursday. && .NEAR TERM /THROUGH TUESDAY NIGHT/... 300 PM Update... Periods of rain will continue through this evening and into the first half of the overnight as an area of low pressure passes by to our north and west. Temperatures are now in the 40s areawide and should continue to slowly rise overnight...reaching 45-50 during the predawn hours. Dew points are also rising, and will reach well into the 40s...this could create areas of fog, especially along and east of I-81. Locally dense fog could even develop; we will continue to monitor the latest observations to see if any SPS or dense fog advisory may be needed for parts of the area. South winds will increase between 8-15 mph, with gusts 20-30 mph overnight (this may help to prevent widespread fog from forming). Rainfall amounts are still forecast to be between a tenth and a half inch for much of the area...except between 0.50 and 1.25 inches across NE PA, western Catskills and northern Oneida county. No change to the hydrologic thoughts, still expecting large, within bank rises on area rivers and streams with a few points perhaps reaching caution stage...will continue to monitor. Tuesday: Cold front sweeps across the area from NW to SE, reaching Syracuse to Penn Yan early to mid morning...Oneonta to Owego and Towanda by late morning. The front finally pushes through NE PA by mid to late afternoon. Surface temperatures surge well into the 40s and even lower 50s out ahead of the front...then fall fairly quickly by afternoon. Higher elevations north of Binghamton should reach the freezing mark prior to sunset (with snow showers mixing in)...mid to upper 30s elsewhere in central NY. Temperatures fall into the upper 30s to mid-40s by sunset across NE PA. Toward sunset a band of lake effect snow is also expected to form near and north of the NY Thruway in the Syracuse area; minor wet accumulations are possible in this area for the afternoon/evening commute. Southwest winds turn west-northwest late in the day, between 10-20 mph. Tuesday night: Strong cold air advection develops across the region, with 850mb temperatures between -10 and -13C. A band of lake effect snow is likely in the evening along the NY thruway corridor and could shift a bit further south at times into central Onondaga, Madison and Oneida counties. Could easily pick up a quick 1-3 inches of snow in the heart of this snow band. Parameters become less favorable for organized lake effect snow after midnight as winds begin to shift around...so lighter snow amounts are expected in this timeframe; under 1 inch. Otherwise a few scattered flurries of snow showers will be possible across the rest of central NY in the evening. Temperatures quickly fall below freezing by mid to late evening across all of central NY and the northern tier of PA...any wet roads could become icy. The other thing to watch will be a subtle wave that will ride along and behind the frontal boundary overnight. This has the potential to bring a period of accumulating snow to our southeastern zones. Model guidance has trended a bit lighter and further east with the snow; but would still bring 1-3 inches of snow from near Scranton-Wilkes Barre northeast in southern Wayne, Pike and Sullivan (NY) counties. Will continue to monitor this closely as well, as a slight shift northwest with this band of snow could bring higher and more widespread amounts. The 12z GFS soundings also show a rather large pocket of dry air in the mid layers, which may make it difficult for ice crystals to form in the cloud layer. Do not have it in the forecast just yet, but would not be surprised to see some localized light freezing rain or drizzle on the NW edge of the precip shield. Overnight lows will be cold areawide, dipping into the 20s. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... Some light snow continues in the southeast zones in the baroclinic zone west of the surface front. Amounts will be light as the area continues to slide to the east. Meanwhile flow, a northwest flow developing over central and western NY as cold advection develops. This will result in mostly light lake effect snow showers over the area, mainly over the Finger Lakes into Oneida county. Flow becomes more favorable Wednesday night into Thursday with a better chance of snow showers into the likely category over northern Oneida county. Working against the possibility of significant accumulations is the much drier air working into the area as the surface ridge builds in. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... 220 PM UPDATE... Active weather continues in the long term as a deepening low rises out of the Gulf of Mexico and tracks up the east coast. Normally this would mean a risk for heavy snow but a complete lack of cold air in place by the end of the week means rain or at best mixed precipitation. Cold air is trapped behind a cold front and secondary low over the midwest and will not stream into the area until after the storm passes. Still, this is a developing situation and will need to be watched. Tweaked the previous grid package based on the latest guidance but the forecast is essentially unchanged from the previous update. 345 AM Update... Moderating temperatures are anticipated late in the week, with quiet weather initially but then messier conditions over the weekend. Though high pressure scoots to our northeast Thursday night into Friday, a dry ridge will still extend over our region which will keep our weather quiet. However, an upper trough will be amplifying over the western Great Lakes-Midwest as we head into the weekend. Ahead of that, most guidance is depicting a negatively-tilting southern stream wave riding up between the amplifying trough and the large high well offshore. This will bring thickening clouds Friday, followed by a good chance for precipitation as we head into weekend. Also, the warm air advection between the trough and high will cause temperatures to rise not just at the surface but especially aloft. Thus precipitation type will be mainly rain, though some freezing rain could occur Friday night if it arrives early enough before surface temperatures get well into the 40s Saturday. Behind the wave, modest cool air advection during the second half of the weekend within the still somewhat moist cyclonic flow of the upper trough, could result in additional snow and/or rain showers. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Broad SW flow will continue across the region tonight with periods of rain and associated restrictions. Most of the terminals will bounce between fuel-alternate required and MVFR. KBGM may spend a good amount of time with IFR conditions. There could also be patchy fog around as the warmer rain falls on the cold ground/snow...bringing localized lower vsbys. Improvement expected after 15Z Tuesday as winds turn northwest and begin to push the low level moisture out of the area. KELM and KITH may improve to MVFR/VFR CIGS around 19-20Z Tuesday. SW winds around 10 kt shift westerly behind the front late Tuesday morning 8 to 15 kts...then to the WNW around 5 to 10 kt after 19Z. LLWS looks to persist tonight with a strong 50 kt jet at around 2000 to 3000 ft. The LLWS eventually diminishes after 12-16Z Tuesday. Outlook... Tuesday night...Restrictions possible in rain changing to snow showers. Periods of snow possible Tuesday night near KAVP, with more restrictions. Wednesday...Restrictions possible in snow showers for NY terminals. Likely VFR at KAVP. Thursday...Lingering snow showers possible near KSYR and KRME, otherwise VFR expected. Thursday night...VFR expected areawide. Friday...VFR to start, then rain moves in late with possible restrictions. Friday night and Saturday...Restrictions likely in periods of moderate rain. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...MJM NEAR TERM...MJM SHORT TERM...DGM LONG TERM...DGM/MDP AVIATION...BJT/MJM