textproduct: Binghamton

WHAT HAS CHANGED

High temperatures on Wednesday are expected to be a few degrees warmer than the previous forecast. Otherwise, no significant change with the latest forecast.

KEY MESSAGES

1) Areas of fog are expected in valley locations tonight and Wednesday morning before a couple days of warmer temperatures and more humid air across all of central NY and northeast PA.

2) Scattered afternoon showers and thunderstorms return to the region Thursday and Friday before quiet weather and high pressure build back in for the weekend.

DISCUSSION

Departing low pressure off the New England coast that brought widespread rainfall of 1 to 4 inches or more to the region will continue to move to the east/northeast tonight. A weak surface high on the western edge of the low is expected to form over the interior Northeast tonight and work in combination with the overall wet antecedent surface conditions to produce areas of fog, especially in the valley locations. Drier air will continue to filter in from the north tonight and cause cloud cover to dissipate. Mostly clear skies and light winds combined with the near surface moisture should be sufficient for fog development.

On Wednesday, the nearly stationary surface high across the region will combine with building heights aloft to produce large scale suppression and a deep layer of dry air to keep weather conditions quiet and dry. A robust amount of sun on Wednesday along with a high July sun angle should allow temperatures to climb into the 80s for much of the region of central NY and ne PA. Surface dew points in the low to mid 60s will make it feel a couple degrees warmer than the air temperature.

A weak short wave may traverse the region quickly Wed night which could limit the extent of fog, but there is still quite a bit of uncertainty (only 15 to 20% chance of showers) in this wave and the chances for rain.

Temperatures in the morning on Thursday will start out very mild in the mid to upper 60s, along with nearly saturated conditions and high dew points in the 60s as well. As the boundary layer mixes through the day, the morning fog and low clouds will dissipate and allow conditions to be favorable for further heating. With 850mb temperatures +16 to +18 degC and residual large scale suppression ahead of the incoming shortwave, surface temperatures should be able to climb well into the 80s and potentially a few lower 90s are not out of the question. Heat indices 90-95 are possible, especially in the lake plain south of Lake Ontario and the interior valley locations.

KEY MESSAGE 2...

As temperatures and humidity increase on Thursday, the threat for scattered showers and thunderstorms increases as well. A southern wave will slide east across portions of the northern Mid Atlantic region in the early afternoon and trigger a few showers and storms from the southern tier of NY south into northeast PA. A northern wave will move slowly in from the northwest during the day and produce a broad area of convection that will move NW to SE through the region into the evening and overnight hours.

Thunderstorm parameters are not overly indicative of severe weather on Thursday. ML CAPE values around 800-1000 J/kg and steep low level lapse rates by the early afternoon will create favorable conditions, however there does appear to be several capping inversions that need to be overcome to be able to tap into this energy. The shear on Thursday is also unfavorable for sustained and mature convection. The early afternoon convection in ne PA should be on the weaker side, and there is likely more concern for strong to a few severe storms with the incoming front from the northwest where wrn/central NY will have more time to overcome the inversions and will also be able to tap into slightly more deep layer shear.

The heat is dampened a bit on Friday but temperatures should still be able to climb into the 80s for much of the region. Dew points remain in the 60s and lower 70s and the short wave may stall out across the area to allow convection to develop Friday afternoon in the vicinity of this boundary. We will need to monitor the threat for stronger storms on Friday and Fri night along this boundary. Deep layer shear will be enhanced with the combination of a modest jet streak aloft and an embedded short wave.

During Friday night the long wave trough rotates through and brings in a more mild air mass with temperatures in the 70s and lower 80s for the weekend and much lower humidity. Rain chances will also be significantly reduced this weekend under a fairly dry pattern.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

MVFR cigs early this afternoon will slowly scatter out, though AVP may hold on to MVFR cigs through tonight. There is a small chance of showers developing in the Southern Tier early this evening. Potential for MVFR vis at ELM, BGM, and ITH if a shower could impact a terminal but odds are low so left out of the TAFs.

Tonight is a favorable set up for fog, with ELM of course having high chances of LIFR cigs and vis. Potential for vis down to a half mile or worse but kept in 2 miles just in case it becomes a low stratus deck. Valley fog will likely get deep enough to affect BGM and ITH, though did not make it predominant yet. AVP and SYR likely escape chances of fog thanks to clouds at AVP, and this is not a favorable pattern for fog at SYR. RME will likely have fog form to the north, that could sneak into the terminal at times.

This fog lifts and dissipates by around 13Z with VFR conditions tomorrow at all terminals.

Outlook:

Tuesday night..Isolated rain showers and thunderstorms could pop up again, but overall trend is towards VFR.

Wednesday through Thursday...Mainly VFR; High pressure building in, morning fog likely, mainly at ELM.

Friday into Saturday...Cold front could move in and stall, leading to persistent showers and thunderstorms with associated restrictions.

Sunday...VFR likely with high pressure building in, morning fog potential at ELM.

BGM WATCHES/WARNINGS/ADVISORIES

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