713 FXUS61 KBGM 290901 AFDBGM AREA FORECAST DISCUSSION National Weather Service Binghamton NY 401 AM EST Tue Jan 29 2019 .SYNOPSIS... A cyclone moving through the Great Lakes will spread snow across NY and PA through Tuesday night. A blast of Arctic air will bring very cold temperatures and wind chills to our forecast area Wednesday through Friday. && .NEAR TERM /THROUGH WEDNESDAY/... 830 PM Update... Latest incoming model trends confirm the adjustments that were made earlier; lowering expected snow amounts along and especially west of I-81 while maintaining the relatively higher amounts to the east. It has become clear that the initial round of snow will be on the light side; as in for the majority of the area only about an inch or less by dawn except for more like 2-3 inches north of the NY Thruway such as where topographical lift will occur in northern Oneida County. Also, some blowing snow can be expected at higher elevations overnight as already detailed in the previous discussion below, before winds slacken during the day. The more interesting part of the system in terms of snow amounts will indeed be midday Tuesday through especially afternoon- evening as an additional wave of low pressure rides up along the front that for a time gets hung up just east of I-81. That will be when the higher snowfall rates of a half inch to one inch per hour may be attained. Biggest point of uncertainty remains the I-81 corridor itself in NY and into northern Tier PA. That is, how far west will that second batch reach courtesy of the additional wave of low pressure as well as better forced ascent behind the front, from jet support during that time. Latest models have the higher probabilities primarily east of Towanda- Binghamton-Syracuse, especially Poconos to Catskills as well as continuing all the way up to the southern Tug Hill Plateau, for that second batch with a pretty sharp cutoff in amounts to the west. There is some suggestion that a brief deformation band could hang for a time around Cayuga-Cortland-Onondaga for maybe a bonus couple late-day inches but models differ considerably. Previous discussion... Winter storm warnings are in effect from 1 am tonight until 1 am Wednesday from Oneida County down into the western Catskills, and Wayne/Pike counties in NE PA. A winter weather advisory is in effect for the same time period from Onondaga county, down to Tioga county (NY) and points east in central NY and across the rest of our NE PA counties not covered by the warning. Snow looks to arrive across our western zones around midnight, then spread east across the rest of the area during the predawn hours. Adjusted snow/QPF amounts for tonight based on the latest guidance, which showed a general decrease in amounts. Snow amounts will be 1 inch or less through 7am Tuesday; except 1 to 3 inches across Oneida and far northern Onondaga counties. Southeast winds increase tonight, 10-20 mph, with higher gusts 30-35 mph possible across the ridgetops of Central NY. Temperatures hold steady or slowly rise into the 20s overnight. Could see localized areas of blowing snow, especially over the higher terrain. Tuesday: First round of snow moves along and east of the I-81 corridor by mid-morning, with a brief break behind this across the central southern tier and Finger Lakes. As the front stalls and a weak wave of low pressure begins to ride north along it, another area of snow will develop and overspread the area from south to north Tuesday afternoon. There will be local upslope enhancements across the southern Tug Hill Plateau and portions of the Catskills/Poconos on a south-southwest flow. This second batch of snow looks to mainly impact areas from about Towanda-- Elmira--Ithaca and Auburn eastward...with the steadiest/heavier snow east of I-81. Back to the west expect only scattered snow showers Tuesday afternoon. Model guidance continues to waver a bit on the exact location of the higher QPF/Snow amounts...but at this time best estimates for snow amounts during the day Tuesday are: less than 2 inches west of Auburn--Ithaca--Elmira-- Towanda, 2 to 5 inches along the I-81 corridor from Syracuse-- Binghamton and Scranton...and 4 to 8 inches across Oneida County down into the western Catskills and Poconos. This system is looking colder overall than it was a few days ago, so am expecting all snow for ptype, but surface temperatures could still warm into the upper 20s to lower 30s Tuesday afternoon. Snow ratios look to be mostly 12-15:1 on Tuesday. There looks to be a period between about 18z Tuesday and 03z Wednesday where the snow growth region is well aligned with an omega max in the column...therefore good flake production (dendrites) are expected. Snowfall rates could occasional approach 1 inch per hour or so in the warning areas Tuesday afternoon and evening...with mostly 1/2 to 3/4 of an inch per hour, moderate, type snow in the advisory areas. Winds decrease some on Tuesday, mainly SSW 6-12 mph, so blowing snow is not expected to be much of an issue. Confidence in this forecast is moderate at this time. If the guidance continues to trend toward a weaker/further east wave of low pressure than lower snowfall amounts would occur. Conversely, if this wave of low pressure is stronger snow amounts could still end up a bit higher. Tuesday night: Periods of snow linger into the evening hours as the wave of low pressure moves off to the east. Most of the steady snow looks to end by midnight, with much colder air and snow showers filtering in behind it. Additional snow amounts of 1 to 3 inches expected east of I-81...with less than 1 inch west. Winds shift westerly, 6-12 mph with patchy blowing snow. Temperatures fall to between 0 and 10 above by daybreak Wednesday, with wind chills 0 to 10 below by morning. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... 400 am update... A very cold Arctic air mass will plow into the region Wed night through Friday with temperatures in the single digits above zero during the day, and dropping back below zero at night. A persistent 5 to 15 mph w/sw wind during this time will produce wind chills -15 to -30 deg F...and a steady band of lake effect snow showers east of Lake Ontario, which may clip portions of nrn Oneida county with more than 10 inches of snow over approximately 36 hours. Large upper level low moving east through Quebec Wed night into Thursday will have an embedded trailing short wave extending back into wrn Ontario and the wrn Great Lakes. This feature will allow the long wave trough to be somewhat flattened...and keep the low level wind flow west-southwesterly. This will keep the bulk of the lake effect snow e/ne of Lakes Erie and Ontario Wed night through Thursday night. Temperatures at 850mb will remain steady around -25 deg C...inducing sufficient low level lapse rates for accumulating lake effect snow...even if the flakes will be in the form of tiny ice crystals with the dendrite zone near the surface. May see snow amounts 8-12 inches in the far northern areas of Oneida county during this time. A Winter Storm Warning for lake effect snow may be needed after we get through the round of snow today and tonight. Overnight low temperatures Wed night will fall into the single digits below zero...with a few lower teens below zero possible in higher elevations. Winds will also be brisk out of the w/sw 10 to 20 mph with gusts 25 mph, which will produce wind chill values 20 to 30 below zero. There will be some improvement during the day Thursday with temperatures getting above zero, but with the winds remaining around 5 to 15 mph, wind chill values will hold in the teens below zero through the day. Winds relax somewhat Thursday night, but remain strong enough to bring wind chills back into the teens and 20s below zero. Friday may be somewhat of a transition day with temperatures climbing back into the teens above zero and west winds only around 5 mph. Boundary layer winds start to go more westerly or just north of west...which will start to shift the Lake Ontario band south...but still north of the Thruway. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... 400 am update... Upper level trough will continue shifting to the east Friday night into Saturday...which will allow the winds to veer more to the n/nw. The lake band off of Ontario will rotate to the south into the ern Finger Lakes, Mohawk Valley and the hills south of Syracuse. However, as this occurs the 850mb ridge axis will begin to slide in from the west, along with a surface high and a gradual warming air mass. So, it looks like there will be at least a short window of opportunity for light accumulating lake effect snow into the Syracuse area Fri night and Sat morning. The large scale synoptic flow pattern becomes quasi-zonal later in the day Saturday with a much more mild air mass as well. High temperatures on Saturday will reach into the lower to mid 20s. There are some differing opinions with respect to what happens on Sunday, but the consensus seems to bring a weak wave ewd through Ontario/Quebec, and brush the nrn counties with a wintry mix, and some light rain to the south. Thermal profiles are widely varying as well, but at this time it looks like temperatures will warm into the mid to upper 30s on Sunday...and again on Monday. A more potent low pressure system looks to be taking shape on Monday over the Great Lakes, which would most likely put NY/PA in the warm sector...with an additional round of wintry mix overnight and rain during the day. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... A cyclone moving through the Great Lakes will spread snow across the terminals through Tuesday evening. The most persistent snows will be along and east of the I-81 corridor. Widespread MVFR conditions are forecast today from KSYR and KRME south to KAVP. The best chance for IFR visibilities and ceilings will be between 18z and 24z. Winds will be southeasterly at 10 to 20 knots this morning, then shift to the west and become gusty later today after a cold front passes. Outlook... Wednesday: Scattered snow showers and some restrictions possible, especially NY terminals. Thursday: Lake effect snow mainly north of SYR-RME; but periodic restrictions still possible in snow showers. Friday: Mainly VFR. Lingering snow showers still possible SYR- RME Saturday: High pressure. Mainly VFR expected. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory until 1 AM EST Wednesday for PAZ038- 039-043-044-047. Winter Storm Warning until 1 AM EST Wednesday for PAZ040-048- 072. NY...Winter Weather Advisory until 1 AM EST Wednesday for NYZ018- 036-044-045-055-056. Winter Storm Warning until 1 AM EST Wednesday for NYZ009-037- 046-057-062. && $$ SYNOPSIS...DJP NEAR TERM...MJM/MDP SHORT TERM...BJT LONG TERM...BJT AVIATION...DJP