textproduct: Binghamton

WHAT HAS CHANGED

Increased shower and thunderstorm chances across central New York Saturday afternoon. No other significant changes were made with the this update.

KEY MESSAGES

1) A narrow corridor of showers and thunderstorms south of Lake Ontario will develop this afternoon. Localized gusty winds are possible.

2) Mild temperatures this weekend with isolated afternoon showers before a period of widespread rain Monday and Monday night, and a typical summer time pattern later next week.

DISCUSSION

KEY MESSAGE 1...

Low pressure system that brought thunderstorms to the region yesterday continues to rotate east/northeastward through Nova Scotia today. On the western edge of this low a cooler air mass aloft is moving in across the eastern Great Lakes and interior Northeast. In addition, there is an upper level short wave sweeping through this afternoon that will help provide the large scale lift and work in collaboration with weak instability and weak low level shear to initiate an area of convection across western NY.

Surface temperatures are currently warming into the upper 60s and lower 70s with dew points in the mid 50s. As the afternoon progresses, temperatures are expected to climb into the mid to upper 70s, but with dew points remaining nearly stationary. This setup will allow for an inverted-V thermal/moisture profile which if there is enough moisture aloft to support high-based convection, could trigger a few dry microbursts. This cannot be completely ruled out, but the probability is on the low side given model soundings are indicating a relatively dry air mass aloft and the presence of at least one fairly robust inversion layer between 18-25 kft. This inversion layer will keep any convection relatively shallow and limit the depth magnitude of any storm that does form.

Any convection that does crop up will dissipate around or just after sunset this evening as the boundary layer collapses and the stable layer dominates.

Key Message 2...

The northwest flow is expected to persist Saturday along with the passage of another weaker short wave and weak instability in the afternoon that may trigger a few isolated showers and weak/shallow storms. Surface temperatures on Saturday will be very similar to Friday...into the low to mid 70s in NY and into the mid to upper 70s in PA. The atmosphere will need to overcome another weak inversion aloft in order to generate updrafts above 10-15 kft, so this will be a limiting factor in producing thunderstorms on Saturday.

By Sunday, the pattern becomes flatter and more westerly and a weak ridge of high pressure aloft builds in from the west as heights aloft rise. Surface temperatures will be warmer on Sunday with widespread highs in the mid to upper 70s...close to 80 in ne PA, and dew points will rise into the upper 50s close to 60...which will allow for increased surface-based instability. Could see a few pop up showers and storms Sunday afternoon, but with no primary forcing mechanism, such as a upper trough/short-wave or cold front and limited deep layer shear, confidence in substantial convection is fairly low.

The attention on Monday turns to a de-amplified upper wave over the Ohio Valley region and an associated surface low and surface warm front extending east across the mid Atlantic region. An abundance of deep moisture associated with this system will be the focus for a broad area of rain that is expected to spread through most of central NY and ne PA during the day Monday.

Probabilistic guidance is indicating that most of the region will see around 1" of rain and some isolated locations could see up to 2" over this 24 hr period. The GFS continues to be an outlier with a more southerly track of the surface low, so we continue to lean more toward the consensus northerly track of the warm front/sfc low.

At this time we are not expecting any hydro/flooding issues with this rain, but we will keep a close eye on how it evolves. The lack of instability with this system will likely limit the rainfall rates, so short-fused hydro concerns should be minimal.

The rest of the week looks active, with scattered diurnal convection, but relatively un-impactful with generally a cyclonic flow over the Great Lakes and Northeast under a mostly mild thermal pattern and near normal temperatures for this time of year.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

MVFR cigs were removed for the next few hours as cloud bases have started to rise. VFR conditions are expected at all terminals into early afternoon. Showers and potentially a few thunderstorms develop after 18Z, mainly across CNY. Right now, prob30s were used at ELM and BGM, then tempos at ITH and SYR where confidence is higher in shower activity near the terminal. RME may be just far enough north to avoid showers, and AVP is likely too far south for any showers.

Outlook:

Saturday through Sunday...Mainly VFR, though isolated to scattered showers possible each afternoon with associated intermittent restrictions. Westerly wind gusts could exceed 20 knots Saturday afternoons.

Late Sunday night through Tuesday...Wave of low pressure with rain, restrictions, and possible embedded thunder. Rain chances decrease Tuesday but lingering showers will still be possible.

BGM WATCHES/WARNINGS/ADVISORIES

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