textproduct: Binghamton

WHAT HAS CHANGED

Chances of precipitation were both expanded and kept longer through most of the morning tomorrow with trough moving in trending towards a more neutral tilt aiding in more lift.

KEY MESSAGES

1) Strong late season cold front moves through tonight bringing a period of heavy rain and thunderstorms followed by a sharp drop in temperatures.

2) Cold to start the week but a gradual warm up is expected into next weekend.

DISCUSSION

KEY MESSAGE 1...

A cold front is making its way east today with a line of showers and thunderstorms that have developed along it in eastern Ohio into the Great Lakes. The front is not going to be fast moving so will not be reaching our region until after sunset. There will be some shower activity ahead of the front this afternoon though much of the precipitation will evaporate before reaching the ground. 0-6 km shear is impressive ahead of the front, peaking at around 60 to 70 knots. The timing of the frontal passage is late, with the atmosphere stabilizing with mainly strong forcing along the front to keep convection going by the time it reaches Steuben county. There is a chance that some strong winds can mix down still so a marginal risk was kept in with the afternoon update from SPC, mainly for the far western Finger Lakes.

The bigger concern will be for some isolated flash flooding with the heavy rain along the front. The forward progress of the front is somewhat slow as it moves through, with the associated trough going from positively tilted to a more neutral so synoptic lift would be strengthening overnight. Precipitable water values are between 1.25 and 1.5 ahead of the front so rainfall rates in its associated showers and thunderstorms could be over an inch per hour briefly. Since greenup is still ongoing and soil moisture is still above average, any place that sees training during the frontal passage may see some water issues.

After the front, temperatures fall into the 30s and even the high 20s at higher elevations of CNY and the Catskills. With the trough trying to become more negatively tilted tomorrow morning, post frontal precipitation looks to linger longer so the chances of precipitation were increased and held onto longer through late morning. The precipitation may hold on long enough that a brief period of snow is looking possible in the mid morning for along I81 and east, but surface temperatures above freezing and incoming solar will prevent any accumulation. Later in the day with cold air continuing to advect in aloft, lapse rates become steep enough in conjunction with the strong heating will lead to instability and convecting rain and snow showers. Graupel cannot be ruled out either with the showers.

A shortwave moving through Sunday night into Monday looks to bring a period of light snow showers to most of the region and accumulating snow of up to an inch at higher elevations, while valleys will see more of a coating on elevated surfaces. A deeper pocket of cold air with 850 mb temperatures down to near -10C on Monday prevents highs from getting out of the 30s for most of the region. Lake effect snow showers is possible for most of the day for the Southern Tier and northward with little to no additional snow accumulation. Monday night will likely be the last really cold night of the year with lows into the mid to low 20s.

KEY MESSAGE 2...

A central US ridge slowly builds in starting Tuesday with temperatures warming up slowly through the week as the cold air mass slowly modifies. With mostly NW flow, the pattern looks to be mostly dry outside of some afternoon showers thanks to day time heating and still cooler air aloft with the trough over New England.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions will quickly give way to MVFR/MVFR Fuel Alt restrictions this evening as a band of moderate to occasionally heavy rain moves from the west. Could see tempo IFR restrictions with this narrow heavy rain band, and can't rule out a rumble of thunder as it moves through ELM, ITH, SYR between 00-03z, RME and BGM 02-05z and AVP 03-06z. Light rain, mist and borderline MVFR to IFR CIG restrictions continue for the rest of the overnight hours. Toward daybreak colder air aloft and at the surface should allow the rain to mix with, or even briefly change to wet snow at most of the taf sites. This will bring some lower vsby and CIG restrictions once again, with IFR restrictions expected at most TAF sites in the 11-16z timeframe, and even LIFR at BGM for several hours. The snow/rain mix is forecast to exit off to the east between 16-18z Sunday, with conditions coming back up to mainly VFR for the afternoon hours.

Gusty south winds 15-25 kts expected out ahead of the front through the early evening hours, winds then turn southwest, and eventually west-northwest overnight into Sunday...remaining somewhat gusty and breezy between 10-20 kts.

Outlook:

Sunday night through Monday morning...Occasional restrictions possible in scattered rain and snow showers.

Monday afternoon through Tuesday...Mainly VFR, then a small chance of showers and minor restrictions Tuesday night.

Wednesday...Front approaches the region with restrictions possible.

Thursday...VFR conditions possible inbetween systems.

BGM WATCHES/WARNINGS/ADVISORIES

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