textproduct: Binghamton

WHAT HAS CHANGED

Increased snow totals across most of NE PA and areas east of I-81 in NY. Winter Weather Advisories expanded westward into more of NE PA.

KEY MESSAGES

1) A few snow squalls possible this evening

2) Coastal system sliding by with some snow for parts of the area late tonight into Sunday

3) Cold temperatures and wind chills Monday afternoon, Monday night and Tuesday. Lake Effect snow showers, heaviest looks to remain north and west of our forecast area

4) Another system around Wednesday night and Thursday with snow showers possible.

DISCUSSION

KEY MESSAGE 1...

A frontal boundary is approaching from western NY at this time. MRMS radar and observations show a linear snow squall approaching western NY. Temperatures are mild though, in the 30s to near 40. CAMs such as the latest HRRR and 3km NAM show this squall approaching our western counties by 4-6 PM, but likely weakening some. The eastward motion of the squall or its remnants slows as well, making it to the northern Finger Lakes and Syracuse area between about 6-9 PM. Overall the squall should continue to weaken by late evening, transitioning to just some isolated to scattered snow showers over north- central NY. Minor accumulations up to 1 inch are locally possible with any of the briefly heavier snow showers or squalls.

KEY MESSAGE 2...

Starting off with the big picture. There is potent shortwave evident on the latest mid level water vapor loop over Oklahoma moving east. The mid level trough is digging into the Ohio Valley, with an enhanced streak of moisture noted along with another small shortwave over Illinois/Indiana.

A jet streak, with enhanced moisture is also evident across the Gulf into the Southeastern US at this time. These three features are all beginning to interact and merge, while turning northward as more upper level energy dives south into the Rockies.

Latest model trends have been for a west/northwest shift of the precip (snow) shield with the coastal low later tonight into Sunday. Official forecast leaned heavily on a blend of the HREF and NBM. WPC guidance was used for QPF, and derived snow amounts. The HRRR and RAP continue to be on the northwest side of guidance, with the RRFS and 3km NAM not quite as far NW as these two other CAMs. The 18z HRRR continues to insist that light to moderate snow will break out over the eastern half of our CWA by 3-5 AM EST early Sunday morning; remaining in place through the morning or even early/mid afternoon hour Sunday as the coastal low tracks northeast. Official forecast shows a similar situation, but not quite as aggressive. Did decide to put lower end likely PoPs into the forecast as most guidance is showing a period of light to moderate snow late tonight into Sunday along and south of I-88, back west to Binghamton and south into most of NE PA. Overall, amounts are still on the lighter side, with a general 1 to 3 inches possible in this area. We will continue to closely monitor track and QPF trends. If amounts and confidence increase some advisory level snow amounts are not out of the question for our far eastern areas, but right now that does not look like the most probably outcome.

Temperatures tonight into Sunday will be plenty cold for all snow with lows in the 20s and highs in the mid-20s to lower 30s. Snow to liquid ratios should average 12-15:1 with this system.

KEY MESSAGE 3...

A much colder airmass will move into the region Monday afternoon and night after the passage of a fairly strong cold front. Scattered snow showers and isolated snow squalls could accompany the frontal passage Monday afternoon. West winds will be quite strong and breezy later Monday, Monday night and Tuesday; between 10-20 mph with gusts of 30-40 mph expected. A large temperature differential (850mb temperatures fall to around -22C) should get the lake effect snow going in full force for most of Monday through Wednesday. However, the mean flow for this event looks to be southwesterly which favors areas west and north of our region. The lake Erie snowband could occasionally stretch into portions of Central NY, bringing localized mainly light snow accumulations at times. High temperatures on Monday will be in the 20s, but falling into the single digits Monday night. Tuesday sees highs only in the 10s with the core of the cold air mass overhead. Wind chills will be below zero Monday evening through Tuesday morning; perhaps 5 to 15 below over the area.

KEY MESSAGE 4...

A clipper system passes well north of the area on Wednesday and could bring some light warm air advection snow to northern portions of the CWA. A front passes through Wednesday night or Thursday bringing scattered snow showers and some lake effect behind it. 850mb temperatures fall to -20C Thursday night as another weak shortwave clipper moves through with light snow. Uncertainty remains in the forecast for the end of the week into next weekend. A cold zonal flow with a few weather systems moving through looks possible. Then indications are for a potential arctic outbreak over very cold air later next weekend into the following week. This will be something to monitor in the coming days to see how model guidance handles the magnitude of the potentially bitter cold air.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

A cluster of snow showers is moving through CNY impacting most NY terminals but BGM so the tempos for MVFR snow showers were kept and adjusted. The IFR snow showers are small so odds are terminals will not fall to IFR but an amendment will be made if it looks like a terminal will be impacted. These showers should be through by around 4Z.

Light snow develops across NEPA and parts of Southern NY with AVP likely seeing periods of IFR or LIFR. BGM has less confidence in snowfall intensity but periods of IFR snow is looking more likely in the early morning.

This snow will be out of the area by around 18Z in NY but may linger around AVP so VFR was not introduced to AVP prior to 0Z for now.

Outlook...

Monday through Tuesday...Occasional restrictions possible in scattered snow showers, especially across Central NY.

Wednesday...An approaching system keeps the chance of snow showers around and associated restrictions, mainly for NY terminals (low confidence).

Thursday...Stronger signal for a front or a low pressure system passing by with restrictions possible (medium confidence).

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...Winter Weather Advisory until 1 AM EST Sunday for NYZ009.