textproduct: Binghamton

WHAT HAS CHANGED

Coverage of snow and mixed rain/snow showers Sunday afternoon through Monday morning has increased across Central NY, and a slight chance of snow showers has also been extended into the high terrain of NE PA. Snowfall amounts during this time remain light.

KEY MESSAGES

1) A strong cold front will bring widespread showers and embedded thunderstorms later tonight through Sunday morning. Isolated strong wind gusts can occur along with locally heavy rainfall.

2) Behind the front it will be breezy and colder, with chances of mixed rain and snow in some parts of the area late Sunday through Tuesday.

DISCUSSION

KEY MESSAGE 1...

A couple of boundaries will be in play across the area today, with the main one being a strong cold front that will move through later tonight into tomorrow morning. A weak cold front continues to push across the area early this morning and the tail end of this front is expected to lift back to the north as a warm front over western and west-central NY this afternoon and evening. This will lead to an area around the western Finger Lakes and north-central PA making it into the warm sector with some spotty showers and thunderstorms ahead of the approaching strong frontal boundary. Model soundings show an inversion in place until mid to late afternoon, which leads to a relative lack in surface instability with 0-6km bulk shear values around 35-40 knots. Low and mid- level lapse rates are also very low, so the risk of this spotty convection being on the stronger side looks low.

A more widespread area of showers and embedded thunderstorms ahead of the front is expected to reach our western areas shortly after midnight tonight and spread east through tomorrow morning. The nocturnal timing of this frontal passage is not optimal for severe thunderstorms, with a continued lack of surface-based instability. However, the front will be strongly- forced with at least some instability aloft, which could result in an isolated damaging wind gust or two. SPC has reduced the coverage of the marginal risk area that was in place west of I-81 to include just Steuben and Yates Counties early this morning.

What may be of bigger concern is the potential for locally heavy rainfall as PWATs rise to around 1.25" with some places nearing 1.50" but the progressive nature of this feature does help. Still, rainfall amounts of 0.30" to 0.75" with isolated higher amounts can lead to localized flooding issues given our very wet antecedent conditions. WPC currently has mainly west of I-81 highlighted under a marginal risk for excessive rainfall. A wide range in high temperatures is expected today given the boundaries in play with highs toward the Tug Hill and Catskills struggling to rise through the 50s to near 60 degrees, while west of I-81 ranges from the mid 60s to the lower 70s.

KEY MESSAGE 2...

In the wake of the frontal passage, temperatures will fall during the afternoon on Sunday as the flow becomes northwesterly and ushers in much colder air. It will remain noticeably colder into early next week. 850mb temperatures fall to around -5C by early evening Sunday and drop to near -10C early Monday morning. This combined with strong low and mid-level lapse rates will be enough to lead to a response off the lakes and the development of scattered snow or rain/snow showers late Sunday through Monday. Snow amounts through Monday morning are expected to be light ranging from a dusting to perhaps near a half inch in some places.

A potent clipper system is expected to move in Monday night into Tuesday, drawing down even colder air into the region and bring a more widespread round of mainly snow showers. Highs Monday mainly range from the upper 30s to the mid 40s, with the valley areas of NE PA reaching the upper 40s to near 50 degrees, but Tuesday is expected to feature highs mainly in the 30s. Overnight lows Tuesday night drop back into the teens and low 20s giving us quite the winter chill. Temperatures are expected to trend back up Wednesday and beyond.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

MVFR ceilings should scatter out as the morning progresses.

A warm front will lift north in the afternoon, bringing scattered rain showers and isolated thunderstorms. Confidence in location and timing of precip coverage is too low at this time to include in most of the TAFs, but chances for showers at BGM have increased so they were included in the TAF.

A cold front pushes through tonight, bringing widespread showers to the area starting after 07z. A marine layer is progged to work its way into the area ahead of the cold front, increasing surface moisture and providing a low level inversion that should trap moisture at the surface, even with the expected gusty winds between 20-30kts. Currently, RME/BGM/AVP are forecast to have IFR ceilings late tonight. There are signals for IFR ceilings at ELM/ITH/SYR but confidence is too low to include them at this time.

A low level jet strengthens in the late evening/early overnight hours, bringing low level wind shear up to FL020 between 40-50kts at all terminals starting after 01z. Wind shear dissipates behind the front.

Outlook:

Sunday...A frontal system crosses the region with additional showers and restrictions possible, especially early in the day.

Monday and Tuesday...Mainly VFR with a low chance of rain and snow showers.

Wednesday...Mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

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