textproduct: Binghamton

WHAT HAS CHANGED

Small adjustments to snowfall across the Finger Lakes as well as in the Pocono Mountains. More snow was added to the higher elevations in both locations.

KEY MESSAGES

1) Clipper system moving through today and tonight bringing widespread light snow.

2) A strong cold front moves in tonight through tomorrow morning that brings in an arctic air mass bringing frigid wind chills to the region through the weekend.

3) A reprieve from the cold pattern is looking more likely mid next week with temperatures rising back towards seasonable averages.

DISCUSSION

KEY MESSAGE 1...

An amplified 500 mb shortwave is descending through the Northern Great Lakes early this afternoon on water vapor imagery and it looks like it is trying to become at least a little bit negatively tilted. Already some light snow is reaching the ground in western NY and this will progress east through the afternoon and early evening. There is still not a lot of moisture for this system to work with but since the trough is looking a bit more amplified, chances of precipitation and QPF were increased slightly through tonight compared to previous forecast. Given the wind expected, snow ratios were lowered slightly so change in total accumulated snow was minimal so most of the area is still in the 1 to 3 inch range. Once the trough is through, winds increase so blowing snow will likely cause impacts to travel through Sunday as treated roads may become slippery as temperatures fall into the single digits.

KEY MESSAGE 2...

An arctic front moves in behind the snow tonight, moving through our area between 3am and 7am. High temperatures will likely be set between midnight and when the front moves through. Temperatures will then fall from the 20s and into the single digits. Winds pick up as well as 850 mb winds approach 50 knots with steep low level lapse rates. Gusts Saturday afternoon and overnight may top out at near 40 mph with sustained winds of 15 to 25 mph. Wind chills will be cold, likely below -10F in valleys and may stay near -20F to -25F at higher elevations.

Overnight Saturday, as temperatures dip below 0, winds do not slacken much so wind chills fall into the -20 to -30 range. Winds look to peak in the Poconos overnight Saturday with gusts along the ridge tops approaching 45 mph where isolated power outages are possible. Lake effect snow is likely in the Finger Lakes and northern CNY Saturday night into Sunday with open water on Lake Ontario, which could help keep temperatures at least regionally warmer (may stay above 0 in aforementioned areas but still windy).

KEY MESSAGE 3...

The "Siberian Express" pattern we have been in that has left us open to arctic air masses is finally getting cut off as a trough develops in Alaska and the western ridge becomes less amplified. There will still be some blocking in Greenland so that would limit the strength of ridging that is possible on the east coast but we should still see temperatures rise to near freezing and be closer to what we expect to see for early to mid February. While we will be warmer, the zonal flow will allow more moisture to get into the plains and with potential west coast troughing, the pattern would be favorable for some lee cyclogenesis in the front range of the Rockies. With the Greenland blocking keeping some cold air filtering in from the north, the precipitation type with any passing low is looking to be mostly snow with some mix. If a larger low can develop and cut into the Great Lakes, then a stronger warm up is possible and would need to be watched for ice jam potential.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/

VFR ceilings and visibilities will begin to fall into MVFR as snow showers move into the region this afternoon. Snow showers will spread eastward throughout the day with visibilities dropping to IFR and LIFR. Some gradual improvement is possible late in the period, but blowing snow may keep IFR visbys around.

South to southwesterly winds will be calm for the majority of this TAF period. An arctic front approaches the region around 03z Saturday and as it moves into the region, winds will become more west to northwesterly and stronger (gusting up to 30kts late tonight/early Saturday morning).

Outlook...

Saturday through Sunday morning...Strong winds and blowing snow possible at all terminals. Occasional ceiling restrictions and lake effect snow at Central NY terminals.

Sunday night through Tuesday...Mainly VFR.

Wednesday... Low pressure system approaches the region with restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Extreme Cold Warning from 4 AM Saturday to 1 PM EST Sunday for PAZ038-039-043-044-047. Extreme Cold Warning from 7 AM Saturday to 1 PM EST Sunday for PAZ040-048-072. NY...Extreme Cold Warning from 4 AM Saturday to 1 PM EST Sunday for NYZ009-015>018-022>025-036-037-044-045-055-056. Extreme Cold Warning from 7 AM Saturday to 1 PM EST Sunday for NYZ046-057-062.