Area Forecast Discussion
Issued by NWS Binghamton, NY

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000 FXUS61 KBGM 240003 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 703 PM EST Mon Jan 23 2017 .SYNOPSIS... A storm will track up the east coast through Tuesday. This system will bring heavy wet snow, sleet, and freezing rain to central New York and northern Pennsylvania. After this storm system passes, a weaker trough moves through Wednesday with a chance for showers. Colder temperatures follow for late week. && .NEAR TERM /THROUGH TUESDAY/... 700 pm Update... No significant changes made to the forecast with precip spreading northward this evening. The leading edge of the precip...generally in the form of -RA with a mix of -FZRA/PL/SN. Still expecting later this evening and into the overnight hours, the precip to change over to all snow as the influx of deep moisture continues and the column cools below freezing, making conditions favorable for either snow or sleet. Previous Discussion... Very complex but significant system will impact the area tonight through Tuesday... Strong system beginning to impact the forecast area as northern edge of precipitation shield is pushing into NE PA. The actual low is still centered near the Carolinas with a strong high over eastern Canada that is feeding colder, drier air into the storm at the lower levels. Temperatures currently in the 30s and of concern, temps already dropping to freezing in places in NE PA due to dry air and wet bulb cooling. As we head into this evening, precip shield will move north to encompass entire CWA. Our forecast models are in overall good agreement on the big picture of this large storm moving slowly from the Carolinas northeast to a point east of New Jersey by Tuesday morning. While cooler air has been filtering in in the lower levels from the E/NE, concern continues to be warm layer aloft which will be trying to advect in from the SE. There are small but very important differences in the models regarding this warm layer which will have a significant impact on precipitation types...this continues to make this a very challenging forecast. NAM still the warmest model while GFS is colder. Gem is in between while some of the higher res guidance leans more toward the NAM. The challenges in these temperature profile details will occur in tandem with the storm spreading heavy precip in the forecast area for the evening and overnight. Based on the consensus of guidance and current conditions, best thinking is that roughly the southern and eastern half of the CWA from Broome County S/E will be dealing with significant sleet and freezing rain and even rain this evening that may really cut down on snow amounts before precip trends more toward mostly snow later tonight. Farther north and west through the Finger Lakes to Steuben County then NE to the Tughill is the area we are most concerned about for 6-8+ inches of heavy wet snow. Even these areas may see sleet and freezing rain this evening for a time. However, as heavy precip moves in which will be forced both by strong upper level forcing and mid level frontogentical forcing this should act to cool the profile in these areas below freezing changing precip to mostly snow. Winds gusting up to 35 mph will also be possible with the storm tonight adding to the impacts of snow/ice...possibly resulting in downed tree limbs and power outages in addition to dangerous travel For Tuesday...low moves from east of New Jersey NE to near Cape Cod by late day. Precipitation will become lighter with time but continue through the morning before easing in the afternoon west to east. Still expect the above mentioned areas in the eastern / southern parts of the CWA may see some freezing rain and sleet at times, especially in the morning. Otherwise, mostly snow in the west. In terms of storm total, still expect 6-8+ inches of heavy, wet snow over our western and northern zones (NW of Broome County). In fact, if a frontogenically forced heavy band sets up this evening this could result in rates of 1-2+ inches an hour and localized storm totals of 10-12+ inches. Snow totals farther S/E will generally be in the 2-6 inch range. Also, big change with this update was adding in freezing rain for many areas but think ice accretion should remain under a quarter inch. Temperatures through the event will remain in the low to mid 30s. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... 300 pm Update... Exiting low pressure just off the coast of New England and trailing upper trough in the eastern Great Lakes will allow the snow and possibly sleet to persist Tuesday night and early Wednesday morning. Snow amounts should be light, as the mid/upper levels dry out quickly with high pressure building in from the west. The overall trend Wed morning will be drier with slightly warmer temperatures into the upper 30s and lower 40s. The ridge will very quickly shift to the east, but the warm air will linger a bit as a pre-frontal trough lifts ewd through the region. This trough will act to product scattered rain showers later in the day Wednesday and Wed night. Thursday will be a transition day with the colder air moving in slowly from the west. As 850mb temps drop to -2 to -4 deg C...the rain will begin to mix with snow...especially in the higher elevations through Thur afternoon. The mix of rain and snow will not result in much snowfall accumulation...and only a trace to around a couple tenths of an inch of liquid...with the highest rainfall amts expected in central NY. && .LONG TERM /FRIDAY THROUGH MONDAY/... 300 pm Update... There will be a noticeable cool down Thursday night as 850mb temps cool to -8 to -10 deg C. Surface temperatures will fall into the mid 20s. This strong push of cold air from the NW will induce weak lake effect bands off Lake Ontario...with the primary area of accumulating snow expected near the Thruway and north. It is still too early to define snow amounts, but several inches are possible through the end of the week. The air mass will become slightly cooler...around -12 deg C later in the day Friday...which may enhance or allow the snow band to become better defined. There is some variation in the trajectories off the lake...but the overall consensus is for a 280 to 290 deg flow...which will keep the snow confined to areas to the north. The flow backs to the w/sw late Saturday and Sunday but the cold air mass persists. So, will likely see the lake band shift to the north out of our forecast area, with temperatures continuing to be rather cold...highs in the 20s and lows in the teens. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... leading edge of precipitation is falling in the form of -RA mixed with -FZRA/PL...accompanied by generally VFR ceilings. As the precip fills in from south to north tonight ceilings are expected to drop to MVFR/fuel alternate...with IFR/MVFR vsbys in the wintry mix, changing to all -SN or SN/PL. Precip type remains in question as rapid changes will be seen this evening. There is the potential for a period of heavy snow later this evening into the overnight across central NY sites (especially for KELM,KITH and possibly KSYR and KBGM) which could bring visbys to less than 1 mile. Precip in the form of SN/PL late tonight/tomorrow morning will begin to taper off through the morning hours (12-17Z) for all sites except KRME where IFR may persist into the afternoon. Ceilings will likely remain MVFR or fuel alternate with flurries into the afternoon. Gusty east winds this evening around 15 knots gusting 20-30 knots...will diminish gradually through the overnight hours backing to the north and nw by tomorrow. OUTLOOK... Tuesday night...Fuel alternate or MVFR ceilings with visibility restrictions in light snow or a mix of snow/sleet. Wednesday...Generally VFR conditions with possible restrictions in rain showers later in the day. Thursday - Saturday...Restrictions possible in snow showers...mainly at KRME and KSYR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Winter Storm Warning until 1 PM EST Tuesday for PAZ038>040-043. Winter Weather Advisory until 1 PM EST Tuesday for PAZ044-047- 048-072. NY...Winter Storm Warning until 1 PM EST Tuesday for NYZ009-015>018- 022>025-036-037-044>046-055>057. Winter Weather Advisory until 1 PM EST Tuesday for NYZ062. && $$ SYNOPSIS...PCF NEAR TERM...PCF SHORT TERM...BJT LONG TERM...BJT AVIATION...BJT/PCF is the U.S. government's official web portal to all federal, state and local government web resources and services.