textproduct: Binghamton

WHAT HAS CHANGED

Adjusted snow chances tonight as lake effect showers move across the area. NBM guidance was not picking up on lake effect snow developing behind the cold front on Sunday so much of the Sunday through Sunday night period had snow chances adjusted and snow amounts increased to 1-3 inches north of the Southern Tier. Chances have increased for precipitation Tuesday as models show a stronger shortwave moving through the area. Higher chances for precipitation were lowered around Christmas as confidence in location and timing is still too low for the higher output the NBM was producing.

KEY MESSAGES

- 1) Lake effect snow and gusty winds diminish as the night progresses and a ridge builds in from the southwest.

- 2) Rising rivers will continue into Sunday. Ice movement still possible and we will need to monitor for potential ice jams.

- 3) A moisture starved cold front moves through Sunday, kicking off lake effect snow across CNY with 1-3 inches possible through Sunday night.

- 4) Several systems will impact holiday travel next week.

DISCUSSION

KEY MESSAGE 1... Lake effect snow and gusty winds diminish as the night progresses and a ridge builds in from the southwest.

KEY MESSAGE 1 DESCRIPTION...

Gusty winds are weakening as the night progresses, with most areas seeing gusts between 25-35mph. A few isolated gusts in the low 40 mph have popped up across higher elevations in CNY, but the widespread lowering of winds allowed the Wind Advisory to expire. Lake effect snow showers continue across the area but have weakened over the past hour. This trend will continue into the early morning hours and these showers should dissipate by sunrise as high pressure builds in from the SW.

KEY MESSAGE 2... Rising rivers will continue into this weekend. Ice movement still possible. Need to monitor for potential ice jams.

KEY MESSAGE 2 DESCRIPTION... Runoff from rainfall over the past day and melting snow will continue to cause the main stem North Branch Susquehanna and Upper Delaware rivers to rise into Sunday. Flow increases downstream are expected to peak Sunday afternoon and are still expected to be sufficient enough to break up and move the established ice cover that has developed in some stretches of these rivers. Monitoring of sensitive and restrictive areas along the rivers for the possibility of ice jam formation and localized flooding will be needed through the weekend. Report active flooding to the National Weather Service as soon as possible.

KEY MESSAGE 3... A moisture starved cold front moves through Sunday, kicking off lake effect snow across CNY with 1-3 inches possible through Sunday night.

KEY MESSAGE 3 DESCRIPTION... An Alberta Clipper will slide eastward, north of the Great Lakes Saturday night through Sunday, pushing a cold Canadian airmass into the region. With mostly zonal flow ahead of this system, there will be no access to moisture from the Gulf or Atlantic so the front itself should not produce much precipitation. Behind the front, 850mb temps will fall to -13 to -15 C during the day and a ridge building into the central US will allow winds in the low and mid atmosphere to line up nicely out of the NW. An upstream connection to Lake Huron and the Georgian Bay looks promising during the late afternoon and evening, allowing some moderate lake effect snow to develop north of the Southern Tier. Currently, 1-3 inches are forecast to fall over this area into Sunday night. We will have to monitor how much QPF is modeled to develop off the lakes as snow amounts could increase, especially if the upstream connection can be made earlier than currently forecast. The aforementioned ridge should continue to build to the ENE and cut off the lake effect by Monday morning. KEY MESSAGE 4... Several systems to impact holiday travel next week.

KEY MESSAGE 4 DESCRIPTION... A parade of shortwaves are progged to ride the NW edge of a strong ridge expected to develop over the central portion of the county next week. The first shortwave should pass to the north Tuesday, with snow in the morning changing to a rain/snow mix by the afternoon as warmer air works its way in from the west.

A shortwave may move through the area on Christmas, but guidance is very uncertain of the timing and location of the shortwave and its impact on the region. Some guidance shows a chance for freezing rain late Christmas Eve into Christmas morning, although many models put the shortwave and most of the precipitation south of the area. Right now, a we have precip starting as snow and changing to rain as the morning progresses. Confidence in freezing rain occurring is still too low to include it in the forecast at this time. With this being the busiest time of year for travel, we will be monitoring how this develops very closely. Christmas day is currently tracking to be pretty warm over the area, with highs in the mid 40s. This warm air is currently modeled to stay around when the next clipper system moves in on Friday, bringing mostly rain to the area.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Generally MVFR ceiling restrictions are expected early this morning at the Central NY terminals, with KAVP likely remaining VFR. All terminals return to VFR by this afternoon, with KSYR and KRME being the last two terminals to return to VFR.

A wind shift from westerly to southerly is expected later this morning. Winds pick back up again this evening with occasional gusts up to 20kts possible at times. LLWS is also expected to develop this evening at all terminals from west to east and then start to dissipate after 06Z.

Outlook...

Sunday through Sunday night...Scattered snow showers across Central NY with occasional restrictions possible, especially at KSYR and KRME.

Monday...Mainly VFR.

Tuesday...Occasional restrictions possible in scattered rain and snow showers.

Wednesday...Mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...None.