textproduct: Binghamton

WHAT HAS CHANGED

Winter Storm Warnings became Blizzard Warnings for Sullivan, Pike, and Southern Wayne Counties. Winter Storm Warnings became Winter Weather Advisories for Susquehanna and Otsego Counties. Steuben County was added to the Winter Weather Advisory. The Winter Weather Advisory was canceled for Madison County. Forecasted snowfall totals were significantly reduced, especially for the higher end snowfall amounts.

KEY MESSAGES

1) A Nor'easter will continue to impact the region today and overnight with snow lingering Monday. Lake effect snow develops behind departing system.

2) A clipper system moves through the Northeast midweek with the next round of snow.

3) The active pattern likely continues through the end of the week with cold air returning next weekend.

DISCUSSION

KEY MESSAGE 1...

Snow showers continue as a low over the Great Lakes begins to weaken and the low that will become a Nor'easter begins to drift off the coast of NC/VA. The coastal system will absorb the weaker low later today and there will likely be a brief lull in snow shower activity for most of the region late this afternoon and into the evening. As the dominant low strengthens and moves up along the coast, snow will spread from south to north. Winds will increase overnight thanks to a tight pressure gradient around the low. With peak gusts of 40 to 45 mph, localized blizzard conditions may be observed late tonight and into Monday. Even if snow ends earlier than expected, freshly fallen snow will easily be lofted. There is potential for some banding late in the event over the Catskills and Poconos as forcing becomes slightly more enhanced with peak snowfall rates between 1 to 2 inches per hour.

Snow will gradually come to an end during the daytime hours Monday as the low drifts up the New England coast. A weak wave behind this system will drop into western NY with additional snowfall for portions of central NY. Then flow becomes west to northwesterly Monday night as lake effect snow develops and is enhanced by this passing wave. Additional accumulations form late tomorrow through Tuesday will range from 1 to 2 inches.

This forecast followed the trends of the 06z and 12z guidance which came in with a much lower QPF footprint over the region. Models have the low a bit more east than previous updates, hence the lower QPF seen in most guidance. A blend of the NBM and HREF was used for QPF, which significantly decreased the northern extent of heavy snow. In addition, snow-to-liquid ratios (SLRs) were decreased for tonight and Monday based on WPC guidance. With strong winds, dendrites break up and lead to slightly lower SLRs than what is often modeled. Snowfall total within the warnings ranges from 3 to 15 inches with the highest amounts in far southern portions of Wayne and Pike Counties in PA. These higher end amounts may still be a little to high, but if the FGEN banding does set up late in this event, some heavy snowfall would then occur. The gradient from south to north is quite sharp as totals taper off to 1 to 3 inches in the Twin Tiers.

With lower snowfall amounts expected. Susquehanna and Otsego Counties had their warnings changed to advisories as confidence is high that most of those areas will remain below warning criteria. There is some guidance coming in wetter so that kept confidence lower to make any additional changes to the current warnings. The advisory was dropped from Madison as heavy snowfall should not extend that far north. Then with the wave dropping in behind the departing system, Steuben County was given an advisory as localized amounts of 4 to 5 inches are expected. After much internal discussion, it was decided to issue Blizzard Warnings for Sullivan, Pike, and Southern Wayne Counties as localized blizzard conditions of 1/4 mile visibility due to blowing snow and gusts over 35 mph are expected.

KEY MESSAGE 2...

A clipper system will slide across the Great Lakes and move into the Northeast early Wednesday morning. With cold air in place, this will be the next round of snow across the region. Initially, there will be decent moisture with this system and some forcing but drier air will work its way in from the west later in the day. As a result, snowfall amounts are expected to be fairly light though some advisories may be needed for northern portions of our region in future updates. The pressure gradient will be tight on the leading edge of this system leading to gusty winds and blowing snow. Areas of reduced visibilities and drifting in open areas will be possible. Depending on how far north this system tracks, there could be some warmer air creeping in from the south. As of now, valley locations will have highs near 40 and with milder conditions, snow would transition to a rain/snow mix or even just rain.

KEY MESSAGE 3...

The pattern will remain active through the rest of the region. A low pressure system will move through the region late Thursday into early Friday though it's track remains uncertain. The ECWMF and CMC have weaker systems that pass south of the region, though precipitation would still be expected. With this solution, colder air over the region would favor mainly snow. The GFS has a more developed low and lifts a warm front through before a cold front quickly follows. This solution would favor rain for some before becoming all snow. With these differing solutions, blended guidance was favored. High pressure then builds over the region in time for the weekend. Guidance is hinting at a cold front on Sunday that would bring additional snow showers and a shot of colder air.

AVIATION /06Z MONDAY THROUGH FRIDAY/

The Nor'easter continues to brings snow across much of the CWA, the question is for how long? CAM guidance shows an inverted upper level trough currently sitting over the area, helping to drive snow showers into CNY and the Finger Lakes region. This trough is progged to dissipate as the Nor'easter continues to move to the ENE. Once the trough dissipates, the snow showers should go with it, leaving the far NW portion of the Nor'easter's snow shield as the only snow game in town. Guidance is somewhat all over the place with timing of the trough dissipating and where the far edge of the snow shield will be and how fast it slides eastward. Current thinking that IFR currently at AVP/BGM/ELM/ITH will continue until around 9-10z, then lighter and more scattered snow should allow for MVFR conditions into the morning hours. VFR conditions return in the afternoon with gusty northerly winds around 25kts. ITH may see some lake enhanced snow showers in the afternoon and evening, which would keep conditions MVFR.

Outlook...

Monday night...Lake enhanced showers may bring MVFR restrictions to SYR and RME. MVFR/Fuel Alt cloud deck expected for the rest of the area.

Tuesday morning through evening...Mainly VFR.

Late Tuesday night through through Thursday night...Occasional restrictions with a couple waves of snow and/or rain.

Friday...Mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Winter Weather Advisory until 7 PM EST this evening for PAZ038- 039. Winter Storm Warning until 7 PM EST this evening for PAZ040- 043-044-047. Blizzard Warning until 7 PM EST this evening for PAZ048-072. NY...Winter Weather Advisory until 7 PM EST this evening for NYZ022- 045-046-056. Winter Storm Warning until 7 PM EST this evening for NYZ057. Blizzard Warning until 7 PM EST this evening for NYZ062.