textproduct: Binghamton

WHAT HAS CHANGED

Increased chances of precipitation this evening into the overnight hours in the Finger Lakes for some lake effect rain showers. Areal coverage of fog tonight and tomorrow were also increased.

KEY MESSAGES

1) A frontal boundary moving through the area will produce isolated showers and thunderstorms into this evening. The front stalls in central PA with more rain expected tomorrow, mainly in NE PA.

2) High pressure builds in briefly Friday into Saturday morning before a large upper level low moves in for the late weekend into early next week with unsettled weather.

DISCUSSION

KEY MESSAGE 1...

A stalling frontal boundary is moving into the Finger Lakes region this afternoon with mainly light rain along the front. With some additional day time heating, better surface based CAPE for the Southern Tier into NEPA will allow for a few thunderstorms to develop. Shear along the front is around 30 knots so if a storm can get tall enough to get into the higher winds above around 10 thousand feet, some small hail would be possible. Low level lapse rates and good humidity aloft will make it difficult for storms to develop a strong downburst so severe storms are unlikely. Tonight with all the low level moisture in place and some clearing at times, widespread valley fog development is expected once again.

Tomorrow, the front that is moving through today looks to stall somewhere in central PA. An area of low pressure propagating along the front will produce a strip of heavy rain along its west to east path. There is uncertainty with how far south the front will stall but it could be draped across a portion of NEPA. If it does, 1 to 2 inches of rain is possible for the Wyoming Valley into the Poconos. Even though rainfall rates dont look to be too high, runoff rates will be higher than typical due to recent rains so some smaller streams and tributaries may approach bank full.

KEY MESSAGE 2...

Once the weak surface low moves east of the region tomorrow evening, the front will continue its progress south with high pressure building in. Morning fog will be commonplace with the longer nights and clear skies on Friday and Saturday. A long wave trough digs in late Saturday into Sunday. Late Saturday into Sunday has some uncertainty with the rain coverage as the 500 mb trough is trying to become negatively tilted. Some of the models have a stronger slow moving low near the Atlantic coast with an area of heavier rain on the NW side of the low. Trends have been bringing some of this rain into NEPA and even into the Catskills. If this low stays to the south, only afternoon showers are expected as cooler air moves in aloft helping lead to afternoon destabilization with day time heating. The Great Lakes are warm enough with the 850 mb temperatures falling to around 5 to 10C to get some lake effect rain early next week.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Mainly VFR conditions are expected through most of the period (at least through 00Z Friday). Fog is expected to develop at KELM late tonight/early Thursday morning, which will likely result in IFR-or-worse visby and ceiling restrictions there. There is also a low chance for some patchy fog at KITH, but with less confidence, only included MVFR visby restrictions within a TEMPO group there.

Otherwise, rain showers are expected to mainly impact KAVP Thursday afternoon, which may result in MVFR restrictions. There is also a chance these showers reach as far north as KBGM, but VFR conditions are expected to remain there at this time. Any remaining restrictions likely end towards the end of the TAF period.

Outlook...

Friday through Saturday morning...Mainly VFR conditions; areas of morning fog, especially near KELM.

Saturday afternoon through Sunday...Showers and potentially thunderstorms with associated restrictions.

Monday...Scattered showers at the Central NY terminals with associated restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

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