textproduct: Binghamton

WHAT HAS CHANGED

Axis of highest snowfall amounts continue to shift east and north, affecting portions of Northeast PA and the Catskills. The probability for freezing rain Friday has diminished, and the probability for sleet accumulation Friday evening for western portions of the Southern Tier and Northeast PA has increased.

KEY MESSAGES

1)Generally quiet and seasonable weather through today; very cold temperatures expected tonight.

2) A system will produce snow and sleet Friday afternoon through Saturday morning.

3) A busy weather pattern is expected to continue with another system pushing through the area Sunday into Sunday night, bringing rain and pockets of freezing rain along with gusty winds.

4) A cold front moves through Monday morning. Lake effect snow, blustery and much colder weather is expected Monday through at least the middle of next week.

DISCUSSION

KEY MESSAGE 1... Temperatures will warm up into the mid- 30s to low 40s for highs on Christmas Day. A strong Canadian high pushes in from the north, with a light northeast flow Thursday night. Skies partially clear and temperatures are expected to drop below zero north of the Mohawk Valley. Expect single digits to mid 10s for the rest of the area overnight into early Friday morning.

KEY MESSAGE 2...

The next system to impact the area continues to show quite the spread of solutions in guidance. Since the last forecast update, the axis of highest snowfall has shifted east and north, and mainly over eastern portions of NE PA, as well as the Catskills. Another change since the previous update is the possibility of freezing rain, which has diminished. Looking at model soundings, there lacks a prominent warm nose, and projects a very cold layer with a blimp of a warm nose existing for areas in NE PA, suggesting the possibility of sleet accumulation overnight Friday, instead of freezing rain. For the rest of the area, the precipitation type could remain as snow, with 850mb temperatures around -10 C.

With higher snowfall amounts creeping northward, we'll continue to monitor the need for additional headlines, especially with newer guidance runs suggesting that the possibility of higher snowfall amounts pushing northward is not out of the realm of possibility. For now, Winter Storm Watches remain.

KEY MESSAGE 3...

The next system enters into the area Sunday afternoon into Sunday night. There will be lingering low level cold air near the surface, but temperatures aloft will warm up and reach +5 to +8C at 850mb, which would help the development of a mix of rain and pockets of freezing rain Sunday afternoon into Sunday night, especially for areas along and east of I-81, including the Catskills and Mohawk Valley. Overall confidence is low on just how much, if any freezing rain will occur, mainly due to uncertainty in the exact thermal profiles near the surface. Temperatures should rise Sunday evening into Sunday night over the region, as increasing south winds and warm air advection take hold out ahead the low pressure center.

KEY MESSAGE 4...

A cold front moves through around Monday morning for most of the area, with temperatures aloft falling to -10 to -12C by Monday afternoon. Exact timing of the front and just how fast temperatures fall during the day Monday remains uncertain at this time. Lingering rain showers will changes to wrap around and lake enhanced snow showers during the day or afternoon on Monday. West-northwest winds increase Monday, Monday night and Tuesday, with strong gusts of at least 25-40 mph certainly possible at times. The setup looks favorable for more lake effect snow (possibly significant) Monday night into Tuesday. As usual, exact flow and therefore lake effect band position and inland extent are not certain this far out in time.

Outside of the main lake effect, it will be very cold and blustery early to mid week with 850mb temperatures possibly getting down near -20C Tuesday morning. Will need to monitor just hold cold it will be, and very cold wind chills could be a factor at times.

AVIATION /12Z THURSDAY THROUGH MONDAY/

VFR conditions are expected to continue through at least mid morning. A dry cold front passes during later morning-midday and winds will veer northwesterly while picking up somewhat through afternoon, with 20-25kt gusts possible at times. Some lingering weak LLWS is expected prior to 14Z for KAVP. MVFR ceilings are expected to form behind the front for the Central NY terminals, but KAVP is expected to remain VFR. A return to VFR conditions is expected this evening and will likely persist through the remainder of the TAF period (at least through 12Z Friday).

Outlook...

Friday morning...Mainly VFR.

Friday afternoon into Saturday morning...Snow with associated restrictions. Sleet may mix in at times for KELM-KAVP Friday night-early Saturday.

Saturday afternoon through Sunday early morning...Mostly dry, but patchy flurries or even spotty freezing drizzle possible with lingering ceiling restrictions.

Sunday midday through Sunday night...Rain and restrictions likely.

Monday through Monday night...Cold frontal passage and gusty winds as rain showers change back to snow showers, especially NY terminals as lake effect becomes dominant.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Winter Storm Watch from Friday afternoon through Saturday morning for PAZ038-043-047. Winter Storm Watch from Friday afternoon through Saturday morning for PAZ039-040-044-048-072. NY...Winter Storm Watch from Friday afternoon through Saturday morning for NYZ022>024. Winter Storm Watch from Friday afternoon through Saturday morning for NYZ025-044-045-055>057-062.