textproduct: Binghamton

WHAT HAS CHANGED

Increased forecast rainfall amounts across the region through tonight. Fog was added to the forecast for Friday and Saturday night. Chances for thunder were removed again for Saturday, as instability will be limited.

KEY MESSAGES

1) A frontal system will bring heavy rain showers with embedded thunderstorms to the region this afternoon through tonight. Additional showers will be possible to start the weekend.

2) Conditions will begin to trend warmer this weekend with above normal temperatures expected next week.

DISCUSSION

KEY MESSAGE 1...

A warm front is pushing into the region this afternoon with widespread rain showers expected. The first wave of showers will impact the Finger Lakes region this afternoon, but rainfall amounts will be light with this first wave. Heavier and more widespread rain showers and embedded thunderstorms will be possible late this afternoon into tonight. Warm air and moisture advection will increase instability this evening out ahead of an approaching shortwave with PWATs increasing above 1.5 inch. Although thermal dynamics looks minimal, with MUCAPE less than 1000 J/kg, forcing and wind shear are more impressive. A potent shortwave and strong 300 mb jet streak punches into western NY later this evening. Strong jet dynamics with our area focused in the left exit region of this incoming jet streak will enhance lift and thus heavier rain showers with embedded thunderstorms are expected. 0-6 km bulk shear is forecast to be in the 40 - 50 kt range, so any stronger convective showers or storms will have to be watched for a severe wind threat. Also, although a weak tornado threat is low, low level helicity will be enhanced in the vicinity of the warm front, so there remains some potential for an isolated and brief weak tornado, even in low topped convection. SPC continues to highlight portions of the area in a marginal risk for severe storms and a 2% chance for weak tornadoes into the western Southern Tier.

Forecast rainfall amounts have been increased with widespread amounts of a half inch plus of rain possible and localized higher amounts of 1 to 2 inches possible in heavier storms. WPC has highlighted portion of the region in a marginal risk for excessive rainfall with isolated flash flooding possible.

Drier air moves into the region behind the departing showers late tonight into early Friday morning. However, the low will linger north-northeast of the region. Wraparound moisture from this low and passing waves along an upper trough will support isolated showers and non-severe thunderstorms for parts of the region. As these showers come to an end late Friday, a weak system will stretch from the Midwest to the Mid-Atlantic. Showers from this system potentially move in as early as Saturday morning, but there is uncertainty on the track. Some models favor a band of dry air across the region and limit the northern extent of this system. Others keep the drier air more north, allowing for showers to extend northward. For now, this update leaned on the NBM that has chances for showers extending into Central NY. Instability looks to be limited with this system so thunder chances were removed from the forecast.

KEY MESSAGE 2...

The aforementioned upper trough slides east Sunday, as a ridge extending well into Canada begins to build into the region and temperatures will trend warmer heading into the start of July. Initially, the humidity will be fairly low Sunday and Monday, but will increase by midweek. Temperatures will be above average, as highs will be in the mid to upper 80s with potential for low 90s in valley locations by Tuesday. There is quite a bit of spread between ensemble members for this warm up. Part of that is likely due to the potential for scattered showers and storms both Tuesday and Wednesday that could help bring some short-term relief from the heat as we will remain on the periphery of the upper ridge.

Also, something to watch for the middle to end of next week is the potential for a few EML plumes pushing up and around the ridge and into the Northeast U.S. The timing and location of these stronger mid level lapse rates will have to be monitored, as any weak perturbation moving through the upper flow aloft could kick off some strong thunderstorms, possibly during overnight hours as well.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

VFR conditons are expected through at least this afternoon, despite showers starting to move into the region. A more organized line of showers with embedded thunderstorms is forecast to develop late this afternoon into the evening hours. The best chance for storms is over ELM/ITH/BGM/AVP. SYR and RME may also see some storms but confidence in storms occurring across the northern part of the area is low given the rain and clouds expected for much of the day.

Patchy fog is expected to move in tonight behind the rain. Currently, ELM has the best chance for IFR restrictions. BGM and ITH may also see fog, but confidence is not high enough to go any lower than MVFR restrictions at this time.

Outlook:

Friday through Saturday...Additional restrictions possible as as several disturbances will bring rounds of showers and thunderstorms.

Sunday and Monday...VFR likely.

Tuesday... Restrictions possible as showers and thunderstorms return.

BGM WATCHES/WARNINGS/ADVISORIES

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