textproduct: Binghamton

WHAT HAS CHANGED

High temperatures were lowered Wednesday with extensive showers and cloud cover expected.

KEY MESSAGES

1) Isolated showers and thunderstorms are expected again today. Showers may produce locally heavy rainfall.

2) A low pressure system will bring widespread rain showers and the potential for strong thunderstorms midweek.

3) The week will end with a period of drier weather though shower chances return this weekend.

DISCUSSION

KEY MESSAGE 1...

Areas of fog will be possible this morning given the moisture added from recent showers, calm winds, and clearing skies. The valleys have the greatest potential for dense fog as visibilities are expected to drop below a mile. Fog will linger through daybreak, slowly clearing out after sunrise.

Isolated to scattered showers and thunderstorms will be possible once again today. These diurnally driven showers and storms will have additional support from weak waves passing along a broad trough. The MLCAPE will be around 500 to 1000 J/kg, but 0-6 km bulk shear will be 20 kts or less suggesting a pulse storm convective mode. As seen in model soundings, there is little wind to mix down later today. Instability does extend into the hail growth zone so small hail would be possible. Given the weak shear though, severe storms are not expected. With weak flow aloft, storms may be slow moving. Despite PWATs only peaking at 1.5 inches today, localized flash flooding may be possible if a slow moving storm develops over an urban or poor drainage area, similarly to what happened in the eastern Syracuse suburbs last evening.

KEY MESSAGE 2...

As the upper level trough digs over the Northeast Monday night into Tuesday, a stacked low pressure system begins to take shape. This system will bring widespread showers and isolated thunderstorms to the region Tuesday morning. Models show instability increasing by the afternoon hours, mainly east of I-81. That may be possible if showers a slow to spread eastward and there is some morning sunshine. However, model guidance have trended slightly faster, so the instability looks to be overdone. Even with good instability, shear is looking weak once again with the exception of portions of Northeast PA where 0-6km shear would be around 30 kts.

This system will spin over the region and slightly enhanced LLJ out of the south will advect in moisture from the Atlantic Tuesday afternoon and into Tuesday night. This is when PWAT values will peak with values between 1.75 and 2 inches. In addition, the Corfidi Upshear vector speed is low, suggesting that training of showers and storms may be possible during this time as well. This and orographic enhancement could enhance rainfall amounts over a short period of time and lead to localized flash flooding. Rivers and streams have been low for awhile now and have taken on any recent rainfall well. Ensemble forecasts have non-zero chances for our typical trouble spots to reach action. There does remain uncertainty where the highest rainfall amounts will be though and these forecasts may change. WPC has a slight risk for excessive rainfall for parts of the region on Tuesday, which seems reasonable given the overall set up.

A dry slot will try to nudge its way into the region Wednesday morning and bring a break from the showers for some. However, this low slowly drifts eastward and will keep wraparound moisture over the region through at least the daytime hours on Thursday before the system slides off and drier air moves in. PWATs will not be as high as Tuesday during this time but additional rain on already saturated areas may further enhance any issues the develop. WPC maintains a Marginal Risk through Wednesday.

KEY MESSAGE 3...

With surface high pressure building into the region, it will be a pleasant end to the work week. Unfortunately, this dry period may be brief as another upper level trough approaches the region Saturday. There remains uncertainty on the shape of this trough and how much it may dig over the region. Shower coverage may be scattered on Saturday before becoming more widespread on Sunday as the trough moves through.

AVIATION /10Z MONDAY THROUGH FRIDAY/

Fog this morning should gradually burn off by 13-14Z at all TAF sites. Attention then turns to isolated showers and thunderstorms popping up again in roughly the 20-00Z this afternoon and evening. Given the spotty coverage opted only to include a VFR shower mention for now. Fog is less likely tonight as some clouds and possibly showers develop to our west overnight.

Outlook:

Tuesday through Thursday... Showers and isolated thunderstorms with restrictions through Wednesday then scattered showers Thursday with possible restrictions.

Friday...Mainly VFR; low chance of a shower or thunderstorm.

BGM WATCHES/WARNINGS/ADVISORIES

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