textproduct: Binghamton

WHAT HAS CHANGED

Continue to adjust dewpoints for Thursday otherwise, no major changes to the forecast package.

KEY MESSAGES

1) Showers and thunderstorms make a return starting Thursday, continuing into the start of the weekend. Increasing humidity along with warmer temperatures expected into the weekend.

2) Active weather returns for later Sunday into the start of the new work week.

DISCUSSION

KEY MESSAGE 1...

Increasing moisture will make a return to the region as southerly return flow increases behind a passing sfc high and with a Bermuda High off the SE coast. Temperatures will also warm some from values earlier in the week.

As heat and humidity build across the region, weak passing disturbances/shortwave troughs will allow for the development of showers and thunderstorms starting on Thursday. Heavy downpours will be possible at times as PWat values increase to 1.75"+ starting tonight. The first of the passing shortwave troughs will cross the area on Thursday, increasing the potential for showers and thunderstorms to develop during the afternoon hours. Most of (if not all of) the area is under a 'Marginal Risk' on Thursday from both SPC and WPC for severe thunderstorms and excessive runoff, respectively. The potential for strong to severe thunderstorms is expected to be limited by less than favorable shear values of sub 30 kts. Instability on the order of 1,500-2,000 J/kg of CAPE, will help with some shower/thunderstorm development as the shortwave troughs pass over the area, but any strong to severe storms should be isolated.

Showers with some thunderstorms will return for Friday as a slow moving frontal boundary approaches from the west, weakening as it tracks into the region. With the moisture laden atmosphere still in place over the region and the slow moving front, the potential for heavier downpours will continue for the day on Friday. Some of the newer guidance stalls the front over the area through the day on Saturday, causing showers and the potential for scattered showers to linger through the first half of the weekend. An incoming larger trough will eventually push what is left of the front out of the area late Saturday. A 'Marginal Risk' for excessive rainfall will continue for Friday and Saturday with the moisture still in place over the region.

Increasing humidity levels along with warm temperatures will start to increase heat index values through the end of the week. The primary areas of concern for areas approaching advisory levels will be the far southern PA counties. But even for these areas, only a small portion of these areas will be close to advisory levels. Otherwise areas of upper 80s to low 90s will be possible at times each afternoon through the end of the week. High temperatures through the first half of the weekend will reach the low to mid 80s for most areas, with some of the lower elevation areas approaching the upper 80s at times.

KEY MESSAGE 2...

The flow will become mainly zonal starting Sunday with shortwave troughs and sfc lows passing across or just north of the region. This will result in showers and scattered thunderstorms to return later in the day on Sunday, continuing into the work week. Warm and humid conditions will remain mostly in place through the start of next week.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Warm and moist air will continue to infiltrate the area through Thursday. Diurnal convective clouds are expected into this evening with lingering altocumulus AOA FL100 tonight. VFR is expected with occasional broken cloud decks. Lower level moisture saturates tonight for a period of late night MVFR and potentially IFR along and south of a line from KELM-KBGM...including KAVP. Confidence in IFR was only high enough at KELM. Expecting any lower ceilings to lift after 12Z Thursday with CCLs forming bases at FL030-040. There is a small risk for isolated to scattered convection overnight and again toward the end of the forecast period but confidence much too low to include mention at this time.

Outlook:

Thursday night through Sunday...Unsettled with repeating times of showers and scattered thunderstorms with VFR ceilings consistently at or below FL050 with intermittent worse cig/vsby restrictions associated with rain/storms.

BGM WATCHES/WARNINGS/ADVISORIES

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