textproduct: Binghamton

WHAT HAS CHANGED

Minor adjustments were made to the forecast at this time. Thunder chances were limited through early Monday morning with little in the way of instability in place. Given some uncertainty in timing and location of the heaviest rainfall late Sunday into Monday, a blend of NBM and WPC QPF was used, which does bring the highest rainfall totals through Monday evening to the Southern Catskills and portions of Northeast PA.

KEY MESSAGES

1) Unsettled conditions return Sunday into Monday with locally heavy rainfall possible as a slow moving frontal boundary crosses the region.

2) A warm and humid pattern will be in place mid to late week next week, with chances for showers or thunderstorms each day.

DISCUSSION

KEY MESSAGE 1...

A shift in the overall weather pattern starts to take shape Sunday into Monday across the region as a more moist southerly flow becomes established. It will be a humid day Sunday with limited sunshine as scattered showers and isolated thunderstorms develop over western portions of the area during the morning and gradually spread eastward and increase in coverage ahead of a slow-moving frontal boundary, which is expected to have a surface low riding along it, and a supporting upper level trough. Meanwhile a strong Bermuda high will start to slowly shift west and between these two features, a strong moisture transport develops with mainly uni-directional shear vectors and warm cloud layer depths increase to nearly 12,000 feet.

As PWATs increase Sunday afternoon into Sunday night to around 1.70- 2.00 inches, locally heavy rainfall is possible late Sunday into Monday, and with winds from just above the surface through 500mb lining up pretty well, there is the concern for training to develop. This potential is also highlighted by MBE Velocity vectors on model soundings under 10 knots, especially between 2 AM and 7 AM Monday. It's during this window in particular that the threat for localized flash flooding seems highest, but if the frontal boundary continues to trend slower, this threat could last longer into Monday. With there being some uncertainty on timing and location of the heaviest rain in this convective set up, a blend of the NBM and WPC was used to remove any convective bullseyes but still highlight the area of greatest concern over the southern Catskills and the upper Delaware River basin given recent heavy rains. The risk for thunder does look low Sunday/Sunday night with little in the way of instability, although shear does start to increase during the early morning hours Monday. For now, thunder was capped at a low-end chance in the forecast. There is a little bit of an increase in instability as Monday rolls around with MLCAPE values increasing to around 500 J/kg and MUCAPE increasing to around or a bit higher than 1000 J/kg, especially east of I-81.

The slow-moving cold front looks to cross the area Monday afternoon and evening as winds shift to the northwest and drier air starts to funnel in later in the day and into Monday night. High pressure then builds in for a brief reprieve from the wet weather for Tuesday and possibly into portions of Wednesday.

KEY MESSAGE 2...

Several features all look to come together to keep the chance for showers and thunderstorms from later Wednesday through late week. The Bermuda high is expected to shift even more west, drawing up plenty of very warm and humid air from the south and driving up dew points. Meanwhile a broad upper trough over the northern Plains, Upper Midwest and Great Lakes will channel waves of energy toward our region and a weakening cut off upper low over the Tennessee Valley looks to gradually drift northeast across the southern and central Appalachians later in the week. The next frontal boundary also looks to try to approach from the west in the Thursday-Friday time frame and perhaps stall a bit. So putting everything together, there will be daily chances for showers and storms with dew points anywhere from the mid 60s to as high as the mid 70s. This will lead to some very uncomfortable conditions with high temperatures mainly in the upper 70s to mid 80s each afternoon.

AVIATION /19Z SATURDAY THROUGH THURSDAY/

Despite extensive cloud cover through the large majority of the current TAF period, conditions are expected to be mainly VFR. There is a chance that MVFR ceilings could sneak into KELM during the mid-late morning hours on Sunday. Otherwise, rain showers will start to move into the region Sunday afternoon, with the highest confidence prior to 18Z being at KELM and KRME. These rain showers are not expected to result in restrictions at this time.

Outlook:

Sunday afternoon through Monday...Rain showers and restrictions likely, with a chance for thunderstorms.

Tuesday...Mainly VFR; low chance for showers and restrictions.

Wednesday through Thursday...Showers likely and isolated thunder; associated restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

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