textproduct: Binghamton

WHAT HAS CHANGED

Minor adjustments made to storm totals for the snow storm today into Monday with an emphasis made to increase totals slightly in some more of the higher terrain/upslope areas of CNY and keep totals lower than NBM in the Wyoming and Delaware River Valleys in NE PA. The end time for the Winter Storm Warning for Luzerne, Lackawanna, Pike and Southern Wayne Counties was moved up to 1 PM Monday from 7 PM as an expected dry slot looks to end snow in this area sooner.

KEY MESSAGES

1) High confidence in a significant snow storm today into Monday; low to medium confidence of sleet mixing in this afternoon and early evening in portions of NE PA.

2) Lingering lake effect snow showers Monday night, with weak clippers and additional chances for scattered lake effect snow showers through much of next week.Temperatures remain below average right into next weekend, with only a slight moderating trend.

DISCUSSION

KEY MESSAGE 1...

Snow currently across north-central PA continues to press to the north and east early this morning and will be overspreading NE PA and the Southern Tier of NY over the next few hours. Snow is expected to reach the I-90 corridor by mid-morning. Confidence remains high in a significant snow storm for the entire area with the heaviest snow occurring this afternoon through the early evening. There continues to be some strong FGEN banding at 850mb and 700mb that would support potential banding during the afternoon and early evening, especially over NE PA, portions of the Southern Tier and into the Catskills, but with how quickly this enhanced lifting moves to the north and east, any heavier bands should be transient. The latest guidance suggests the potential to start seeing snowfall rates nearing or reaching 2 inch per hour rates is around 19Z with a few pockets of snowfall rates nearing 3 inches per hour possible through about 03z.

The potential for sleet mixing in remains a concern across portions of NE PA and possibly southern Sullivan County. Around 20-21Z, 850mb winds increase to about 50 knots out of the SE driving the warm nose aloft to the north and west. The NAM remains the most bullish so to speak with getting sleet into this area this afternoon and evening and typically does best when it comes to having a warm layer involved, but the Canadian and the GFS are not too far away either. Because of this potential, SLR values were lowered after 18Z in this region, especially in the lower elevations to keep snow totals around 10 to 12 inches. Some high res. guidance also shows a dry slot moving into the area around 00-01Z which can also aid in keeping snow totals lower in this area. Across the rest of the region, a general 12 to 18 inches with localized amounts nearing 2 feet, especially in the Catskills, is expected. A couple of other pieces to the puzzle that will be monitored are potential pockets of sinking air moving in in the mid levels after the FGEN bands depart, and the easterly flow at the surface. Could one or both of these result in any drier air mixing in or downsloping to reduce snow totals across CNY, especially west of the Catskills.

The trend of the steadier snow exiting and ending slightly faster continues late tonight, but additional snow showers are expected throughout the day Monday from wrap around moisture from the departing low located off the New England Coast. QPF amounts were lowered slightly from NBM after 06Z to reflect the quicker exit. Some areas of blowing snow will be possible Monday as winds increase in the afternoon, especially across CNY. Temperatures will continue quite cold as well with temperatures in the single digits and teens. An upper trough swinging through late in the afternoon and evening on Monday will lead to west- northwest flow developing along with some lake effect snow off of Lake Ontario for the northern Finger Lakes region and Syracuse metro that could keep travel conditions slow around the I-90 corridor.

KEY MESSAGE 2...

As the upper trough mentioned above departs to the east and weak ridging builds in aloft, winds become more west then southwesterly early Tuesday morning which will lift the lake effect snow to the north of the I-90 corridor toward daybreak. Lows Monday night will be in the single digits to a few degrees below zero.

A weakening clipper approaching from the north and west Tuesday can lead to some scattered light snow showers across the area, especially over CNY. This system will bring with it a reinforcing shot of cold air and as the upper level shortwave with this disturbance swings through, west to northwesterly winds are expected to lead to lake effect snow showers dropping back south into CNY Tuesday night into Wednesday. Highs Tuesday range from the upper single digits to mid-teens. Lows Tuesday night range from about 5 degrees above to 5 degrees below zero.

The next deeper 500mb trough drops into the region Wednesday night and Thursday, along with a potential clipper system. This will keep chances for snow showers in the forecast, especially across CNY. At this time, model guidance keeps a rather stagnant pattern over the area right into next weekend, with the a 500mb trough in place across the Great Lakes and Northeast, and occasional clipper systems and lake effect snow showers off of Lake Ontario. With the NBM being underdone with this lake effect setup, the Canadian was blended into the forecast through the end of the week to increase PoPs in the favored locations. Temperatures remain steady, with lows 5 below to 5 above zero, and highs in the upper single digits to teens through at least Friday.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Snow is marching northward at a pretty good clip this morning and steady snowfall is expected to reach SYR and RME by 14Z. As the snow moves in, visibility is dropping pretty quickly down to LIFR. The steady snow will continue through the afternoon with all terminals expected to see visibility drop to below airport this afternoon and evening.

Snow does begin to taper around AVP (Could mix with sleet at times) by around 0Z with snow holding on longer north. SYR, ITH, and RME may hold onto IFR and worse vis from snow through 12Z. BGM and ELM are on the edge of the dry slot that will affect AVP so there is the most uncertainty if they can hold on to IFR or worse or see at least some improvement to MVFR after 0Z and before 6Z. However, toward the end of the TAF period, the snow is expected to become more intermittent and start to taper off around BGM and ELM if there is no improvement from the dry slot.

Outlook...

Monday...Lingering snow showers and/or lake effect possible with associated restrictions. Blowing snow in the afternoon as NW winds gusts 25-35 mph at times.

Tuesday thru Thursday...Isolated snow showers with associated restrictions, otherwise mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Winter Storm Warning until 7 PM EST Monday for PAZ038>040. Winter Storm Warning until 1 PM EST Monday for PAZ043-044-047- 048-072. NY...Winter Storm Warning until 7 PM EST Monday for NYZ009-015>018- 022>025-036-037-044>046-055>057-062.