textproduct: Binghamton

WHAT HAS CHANGED

High temperatures were lowered on Sunday from NBM with most guidance running noticeably cooler with the cloudy and rainy conditions expected. Thunder was also removed on Sunday north of the NY/PA border with little to no instability.

KEY MESSAGES

1) Temperatures will be running slightly cooler than average today, but it will be a dry day with sunshine dimmed by high clouds.

2) Rain returns later tonight into Sunday as the pattern becomes more unsettled with several rounds of showers possible next week. Fall-like temperatures are also expected.

DISCUSSION

KEY MESSAGE 1...

Surface high pressure currently centered over eastern Ontario will keep conditions dry across our area today. Sunshine is expected to be dimmed by mid and high level clouds that are streaming in from the west associated with the system that will be bringing our next chance for rain later tonight into Sunday. Clouds are expected to thicken later in the day as high pressure slides off to the east. After a cool start early this morning with temperatures primarily in the 40s and low 50s, high temperatures this afternoon will be a few degrees below average, but overall it will be a fairly comfortable day with light winds and low humidity as highs range from the mid 60s to the low 70s. KEY MESSAGE 2...

A low pressure system will approach from the west later tonight, potentially kicking off some isolated to scattered showers ahead of it. Rain will become more widespread early Sunday morning and continues throughout the day as the low moves across the region. The track of this low has trended a bit farther north over the past 24 hours, so there is still a little bit of uncertainty there. Most guidance was lower than NBM with regards to high temperatures Sunday, so they were lowered about 2 to 4 degrees, ranging from the upper 50s to the mid 60s.

The NAM does show around 500-1000 J/kg of MUCAPE across parts of NE PA, mainly over Luzerne, Lackawanna and Wyoming Counties, Sunday and there is 30-40 knots of shear, but lapse rates are low, so just a couple of rumbles seem possible. Thunder chances were removed completely north of the NY/PA border.

WPC continues to highlight from around the NYS Thruway on south in a marginal risk for excessive rainfall Sunday. Looking at guidance, PWATs peak mainly between 1.50 and 1.80 inches (but closer to 2 inches in some spots on the Euro) and warm cloud depths will near 12k feet. There is also increasing winds aloft, most notably around 850mb that could enhance lift. All of this can lead to some periods of locally heavy rainfall. Guidance is still spread on exactly where the highest rainfall totals will be, though the general focus seems to be across the Twin Tiers, NE PA and into the Catskills with a widespread 1 to 1.50 inches of rain, with localized higher amounts, through Monday. Looking at the latest flash flood guidance, both 3 hour county and headwater flash flood guidance is about 2 to 2.5 inches of rain, except toward the Poconos where it is higher. Soil moistures are also abnormally dry across north-central NY, so confidence is low for any flash flood issues through some ponding in urban and poor drainage areas will be possible.

This low moves east of the region late Sunday night and drags a front south of the region. Behind this system, high pressure brings drier air back in for Monday. Being in zonal flow, some passing showers will be possible across portions of NE PA and the Catskills. However, the latest model runs are a bit farther south with the placement of the high, which then deflects most of the moisture to our south, so shower chances have trended lower. Broad surface high pressure centered of eastern Canada will then compete with additional disturbances Tuesday through Thursday. An upper low will develop over the Great Lakes region early in the week and still under zonal flow, showers will continue to move through the region. Just how far north these showers will be is uncertain with the high pressure to the north. The upper low will move little by Wednesday. East to southwesterly flow will advect Atlantic moisture inland, supporting showers midweek. The upper low becomes an open wave as a surface low develops over the Mid-Atlantic coast. This low will slide up the coast with the next round of showers on Thursday.

The first extended taste of fall is expected next week. Temperatures will only max out in the 50s and 60s before falling into the 30s and 40s at night. Fall officially begins this Tuesday at 804 PM EDT.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

No major changes with the 6Z update. VFR conditions are expected across the region through the TAF period with high pressure in place. There is a small chance for early morning fog at ELM, but with upper level clouds and the dry air mass in place, fog development will be limited. Rain will try to push into northeast PA and the Southern Tier towards the end of the forecast period, with AVP being the most likely site to see rain showers before 06Z Sunday morning.

Outlook...

Sunday...Rain expected for much of the period. Periods of IFR restrictions possible.

Monday through Wednesday... Scattered rain showers and associated restrictions possible. Uncertainty still remains for this forecast period.

BGM WATCHES/WARNINGS/ADVISORIES

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