textproduct: Binghamton

WHAT HAS CHANGED

Increased QPF amounts today through this evening across portions of NE PA, especially around the Poconos.

KEY MESSAGES

1) A wave of low pressure moving along a stalling boundary will lead to some rain at times today, mainly from the NY/PA border on south. The heaviest rainfall is expected toward the Poconos.

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

DISCUSSION

KEY MESSAGE 1...

A frontal boundary currently draped across west-central NY into NW PA will continue to gradually slide to the south and east today, and may even stall out for a time across south-central PA and just south of NE PA. A wave of low pressure is expected to ride along this front and pass south of the Poconos, leading to a period of some steadier rainfall, especially from the NY/PA border on south across NE PA. There can be an embedded stripe of locally heavy rainfall across NE PA, and while there is a bit of uncertainty on where this may set up, the best chance looks to be from around the Wyoming Valley into the Poconos. Most model guidance show PWAT values rising toward or a bit above 1.50 inches from the Twin Tiers on south, deep moisture profiles on soundings and warm cloud depths of about 10-12K feet. The NAM also shows a developing jet streak over NE PA into the southern Catskills during the afternoon with 500mb winds increasing to around 60 kts. While other deterministic guidance is not as bullish, it does show increasing winds aloft in this area as well enhancing lift. As a result, it looks like there can be enough enhancement for a narrow corridor to see rainfall totals this afternoon into this early evening approaching an inch from southern Luzerne to Pike Counties. A sharp cutoff in rainfall totals is expected north of here with about a tenth to 1/3rd of an inch of rain expected for the Twin Tiers and into the Catskills.

The latest HREF gives a 30% chance of greater than 1 inch of rain in 3 hours from around I-84 on south this afternoon and a 50% chance of greater than 1 inch of rain in 3 hours just south of Luzerne and Pike Counties. In fact, the HREF has a 10% chance of greater than 3 inches of rain in 3 hours not too far to the south and east of the Poconos, indicating that potential sharp gradient in heavy rainfall in the region later today, and there is the potential that this could try to shift a bit farther north given recent trends. WPC does have a Marginal Risk (Level 1 out of 5) for excessive rainfall across NE PA where isolated flash flooding cannot be ruled out, especially in low lying and poor drainage areas. From a convective standpoint, there looks to be little in the way of instability today into this evening, so the risk for thunder is very low. It will be a cooler day with highs in the 70s areawide.

KEY MESSAGE 2...

Once the surface low moves east of the area this evening, the front will continue its progress south with high pressure building in from the north. As skies clear, areas of fog are expected to develop quickly tonight. It will be a noticeably cooler night with lows in the upper 40s to the mid 50s. Highs Friday and Saturday will be in the mid 70s to lower 80s.

A long wave trough digs in later 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 with a surface low moving across the eastern Great Lakes, while another slow-moving low lifts north near the Atlantic coast with an area of steadier and locally heavier rain on the NW side of the low. Some guidance tries to bring some of this steadier rainfall into NE PA and the Catskills, but if the low can stay far enough to the south, it may take until Sunday to see more widespread shower activity as the upper trough moves overhead. The Great Lakes are warm enough with the 850 mb temperatures falling to around 5 to 10C to get some lake effect rain showers early next week.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Any early morning low clouds and fog should clear by 13Z leading to mainly VFR conditions through the most of the TAF. Otherwise, rain showers are expected to mainly impact KAVP this afternoon, which may result in MVFR restrictions. There is also a chance these showers reach as far north as KBGM/ELM, but VFR conditions are expected to remain there at this time. Any remaining restrictions likely end in the evening, but IFR fog is expected to return again overnight.

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.