307 FXUS61 KBGM 051604 AFDBGM AREA FORECAST DISCUSSION National Weather Service Binghamton NY 1104 AM EST Sat Jan 5 2019 .SYNOPSIS... A low pressure system moving across the Delmarva will keep rain over our southern and eastern forecast areas today. A cold front will move through tonight and trigger a few light snow showers across the region into the day Sunday. && .NEAR TERM /THROUGH SUNDAY/... 1100 AM Update... Temperatures have risen above freezing for just about all locations seeing precipitation, therefore the winter weather advisory was allowed to expire on time, at 8 AM this morning. Light rain continues along and SE of the I-88 corridor and across most of NE PA late this morning. Coastal low continues to spin off the DELMARVA/NJ coast, and is bringing a steadier band of rain from near Scranton to Monticello and points east. All of this rain will gradually shift off to the south and east, eventually out of the forecast area later this afternoon. Additional rainfall amounts will be mainly under a tenth of an inch...except locally around a third of an inch in Sullivan/Pike counties. Across our western zones subsidence is occurring, with partly to mostly sunny skies across the Finger Lakes. Expect a few breaks of sun to move east this afternoon, across Central NY. Temperatures should rise into the upper 30s to mid-40s this afternoon. Winds shift northwesterly, around 10 mph. Clouds then quickly move back in from western NY this evening, with scattered snow showers developing overnight as modest cold air advection begins. Temperatures only gradually fall overnight, dipping down into the upper 20s to mid-30s toward daybreak. 205 AM update... Temperatures this morning are much colder than the models indicated. With readings in the middle-20s across portions of the Twin Tiers and Catskills, we opted to issue a short term winter weather advisory for our central forecast area effective until 13z. We anticipate temperatures will sufficiently rise over the next 2-4 hours and allow us to cancel at least a portion of the advisory. The Delmarva storm system will slide northeastward today and pull rain across our eastern forecast area, while dry air filters into the Finger Lakes and Central Southern Tier. Rain will exit our region during the afternoon hours. Colder air sliding across Lake Ontario will generate lake effect snow and rain showers tonight. Accumulations will be light. There is some indication that ice crystal formation will once again be an issue. While spotty freezing drizzle is possible, temperatures are marginal for freezing precipitation. We don't anticipate including freezing drizzle in the lake activity with this forecast package. Light lake effect snow shower activity will continue over the northern half of our forecast area on Sunday. Temperatures will reach the middle-30s. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... 415 AM Update... After quiet conditions Sunday night through midday Monday, main concern continues to be potential for a wintry mix event late Monday through early Tuesday. High pressure will pass overhead Sunday night with a period of mostly clear sky between breakup of stratocumulus, and incoming high thin clouds towards dawn. The resulting radiational cooling of a cold dry air mass will send lows into mostly the teens, though a good chunk of Central NY is likely to reach single digits to 12 degrees, especially east of I-81 and including Cortland-Syracuse. Brief filtered/partial sun is possible at dawn but clouds will be quickly increasing and thickening Monday morning. Confidence in details of system for Monday afternoon through early Tuesday has actually gone down, as models are presenting a wider range of possibilities and amounts instead of converging towards a single solution. What all models have in common, however, is a window of time in which a layer of warm air aloft will cause sleet or freezing rain to become a primary precipitation type. How long each precipitation type lasts is in question and will also vary by area, but the general progression will be as follows. The front end begins as snow- sleet, then freezing rain will also enter the picture with time Monday night as the warm layer lowers/cold near surface layer thins, before plain rain as surface also warms into early-mid Tuesday. Model consensus trend is for the better accumulating snow potential to be shoved further northeast than before, with 1-3 inches probably being reserved for Oneida-eastern Otsego- eastern Delaware and mostly less than an inch for the remainder of the area; almost none south and west. Big question for how much of the liquid-to-freezing precipitation will be sleet versus freezing rain, but just about the whole area could end up with a very light glaze. Primary problem time in that regard would be late Monday afternoon-early evening southwest, moving across areawide during Monday night, then far northeast by dawn Tuesday. There will be a solid pressure gradient between high pressure stretching across New England into the Atlantic, and the low pressure in western to central Ontario. The south-southeast flow in between could get a bit zesty Monday night especially higher terrain, as well as channeled drainages/downslopes of the Finger Lakes. Models are also starting to hint at a large elevation dependence for total precipitation amounts, with potential wind shadowing causing relative minimums in the Central Southern Tier to Finger Lakes in NY as well as perhaps the Wyoming Valley in PA. Likewise, northern Oneida could get upslope enhancement to snow/sleet, and thus somewhat higher expectations for snow accumulations there. Temperatures will continue to their early morning surge Tuesday, to achieve highs of upper 30s-upper 40s during the day. Rain/wintry mix in the east will also quickly end, yet another wave wobbling in attached to the Canadian upper low could bring another round of mostly rain showers through the area later Tuesday afternoon. Cold air advection will be inbound, and thus additional showers into Tuesday evening may start to change to snow as detailed in the long term portion of this discussion. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... Tuesday night: Another shortwave upper level trough moves into our area from the Great Lakes region. This trough could become a closed mid and/or upper level low as it moves across northern NY. A surface lows is also expected to develop and move just north of our CWA. This system could bring another few tenths of an inch of QPF. Precipitation type would likely start out as rain Tuesday evening, but would then changeover to snow from NW to SE, as colder air filters into the area. Exact details remain uncertain on this system, but it could bring another light accumulating snow to parts of the area. Low temperatures gradually fall into the upper 20s and lower 30s late at night. Wednesday and Wednesday night: A slow moving upper level trough remains centered over the area. Much colder air will be in place, with 850mb temperatures around -8 to -12C...and surface temperatures holding in the lower to mid-30s for most locations during the day. A moist synoptic wrap around flow, and lake enhancement will produce high chance PoPs for snow showers. Overnight lows dip down into the lower to mid-20s. Thursday: Colder, with still a chance for lingering lake effect snow showers as the upper trough only very slowly moves off the East Coast. Highs range from the lower to mid-20s north, to lower 30s in the Wyoming Valley of NE PA. Friday: Brief upper level ridging moves in for dry weather and seasonable temperatures. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... A storm system moving across the Delmarva will spread rain showers and MVFR conditions across KAVP, KBGM, KITH, and KELM this morning. Ceilings will mainly be between 1200 and 2500 feet in the rain showers, with visibilities of 2SM to 5SM. Spotty freezing rain and light snow will be possible at KITH and KELM through 13z. The storm system will shift the rain and clouds eastward this afternoon, with the region returning to VFR conditions. Light lake effect snow showers are expected to bring occasional MVFR visibilities and ceilings into KSYR and KRME after 03z Sunday. Outlook... Saturday night and Sunday...Mostly VFR, but possibly MVFR at KSYR/KRME in scattered lake effect snow showers. Sunday night through Tuesday...Mainly VFR through Monday morning then lowering ceilings to MVFR and IFR with rain and/or snow by Monday night. MVFR and IFR ceilings with more precipitation through Tuesday. Tuesday night through Wednesday...Restrictions possible in snow showers, mainly KRME/KSYR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...DJP NEAR TERM...DJP/MJM SHORT TERM...MDP LONG TERM...MJM AVIATION...DJP