textproduct: Binghamton

WHAT HAS CHANGED

The lake effect snow warning has been expanded to include northern Onondaga and Madison Counties through 8 AM Wednesday morning. Lake effect snow totals were adjusted south a bit and slightly higher compared to the last forecast. Scattered snow showers were added into the forecast this afternoon and evening across the Twin Tiers and Northeast PA.

KEY MESSAGES

1) Much colder tonight with heavy lake effect snow for portions of Onondaga, Madison and Oneida Counties through Wednesday morning. A lake effect snow warning is in effect for these three counties until 8 AM Wednesday morning.

2) Scattered snow showers and perhaps isolated snow squalls for NE PA and the Twin Tiers this afternoon and evening

3) Temperatures return to near average levels mid to late week, with mainly quiet weather.

4) Several frontal systems move through bringing periods of showers for the weekend, with continued near average temperatures.

DISCUSSION

KEY MESSAGE 1...

Lake effect snow showers have already developed over the region on a westerly flow. Expect the flow to veer more northwesterly early this evening after the passage of a shortwave trough. This will open the door for a lake to lake connection off of Lake Huron, Georgian Bay and Lake Ontario. Most of the CAMs are in decent agreement that a band of well organized, heavy lake effect snow will impact Oneida, northern Onondaga and northern Madison Counties starting around sunset, then drift south toward I-90 by the mid to late evening hours. Forecast soundings show lake induced equilibrium levels up to around 10k ft with a bullseye of strong Omega nearly collocated within the snow growth layer; especially for the overnight hours. Surface winds will be decreasing overnight as well, which should allow for snow to liquid ratios to reach at least 20:1 within the expected lake effect snow band. The current official forecast was collaborated with neighboring WFOs and leans heavily on the CMC- Regional model for QPF and band placement (but not quite as aggressive). Overall, the model guidance seems to have shifted a bit south with the QPF, PoPs and snow amounts with the latest runs. Therefore, official snow amounts were adjusted accordingly and the Lake Effect Snow Warnings were expanded to include northern Onondaga and Madison counties. The heaviest snow is expected to fall across northern Onondaga east along I-90 into Central Oneida County where 6 to 12 inches of snow is expected. There will be a very sharp gradient to the snowfall totals, with the City of Syracuse forecast to be on the edge of the lake effect snow, and only 1-2, perhaps 3 inches of snow within the City limits. The lake effect snow will quickly shift north and become scattered showers around or just after daybreak Wednesday morning as surface winds turn southerly ahead of the next frontal system. Overall forecast confidence is moderate to high for this lake effect event, however some uncertainty remains in exact location specific snow amounts (as is usual for lake effect).

KEY MESSAGE 2...

A shortwave trough is visible on the latest mid level water vapor satellite loop pushing into east-central PA this afternoon. Regional radar shows scattered to numerous snow showers developing, with some small west-east oriental linear snow bands as well. The snow squall parameter is 2-4 across western PA and western NY at this time; supported by steep low level lapse rates (pushing 10.5C/km), some modest instability, cold low level temperatures and lingering breezy west winds. The snow squall parameter looks to hold between about 1-3 through sunset over NE PA, which could be enough for isolated heavier convective snow showers...which may start to accumulate on some roads etc near sunset...and will also reduce visibility. The snow shower activity will quickly diminish and end by 9-10 PM this evening for this area.

KEY MESSAGE 3...

Quiet and seasonably cold weather is expected on Wednesday. After some lingering lake effect snow showers or flurries in the morning, winds turn southerly and skies become mostly sunny. A decaying warm front moves through on Thursday, bringing more clouds and slight chance for rain or snow showers. A more organized front and trough moves through Thursday night with rain and snow showers likely, but precipitation amounts will be light; under a tenth of and inch. High pressure looks to be in place for most of the day on Friday, with partly sunny skies and seasonable highs in the 40s to near 50.

KEY MESSAGE 4...

A fast moving system drops through the area Friday night bringing a period of rain/snow mix. Chances for showers linger through the rest of the weekend due to several fronts moving through. Exact timing remains uncertain, especially on a potentially stronger cold front Sunday into Sunday night. Latest WPC guidance is leaning faster with that cold front dropping int from the north and therefore colder on Sunday for Central NY. This will be something to watch for the upcoming weekend weather. Model guidance is in good agreement that below normal and much colder temperatures will be around early next week.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Scattered snow showers will continue for at least the next couple of hours. These could bring brief IFR visibilities to AVP and BGM. Once these come to an end, most terminals will be VFR. A more defined lake effect band will drop south into the region tonight and impact SYR and RME. Visibilities will range from MVFR to IFR. Ceilings will likely fall into MVFR as well. By around 12z, these snow showers will be ending and both terminals will return to VFR for the rest of the TAF period.

Winds will remain gusty yet this evening. Overnight, winds then become light and variable will will remain fairly light through Wednesday.

Outlook:

Wednesday...Mainly VFR.

Thursday and Friday...Mainly VFR; a low chance for spotty rain/snow showers.

Friday night through Saturday...A chance for additional rain/snow showers as a clipper moves through the region; low confidence on timing.

Sunday...Restrictions possible as another system moves through the area.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...Lake Effect Snow Warning until 8 AM EDT Wednesday for NYZ009- 018-036-037.