textproduct: Binghamton

WHAT HAS CHANGED

Increased coverage of precipitation chances this evening and into tonight.

KEY MESSAGES

1) Thunderstorms are expected to develop once again this afternoon, bringing a threat of gusty winds to the Southern Tier and southward.

2) A weak, but deepening surface low passes south of the region Sunday evening into Monday, with widespread rain and cooler conditions expected to start the week.

3) Upper level ridge moves west, with more seasonable temperatures this week into next weekend along with several chances of showers and thunderstorms.

DISCUSSION

KEY MESSAGE 1...

Clouds have mostly cleared early this afternoon allowing for heating to take place across the Southern Tier and northward. NEPA has been sunny for much of the day and has warmed into the 90s though dew points are mixing down a bit. Wind shear is slightly stronger today than yesterday, though the better shear is north across the I-90 corridor. There is some uncertainty across CNY where the shear is given the clouds and more limited heating but cooling cloud tops over Lake Ontario indicating that may be it wont take much instability to get storms to fire.

Across the Southern Tier and south, mesoanalysis is indicating better mid level lapse rates despite the less shear, and DCAPE is about the same as yesterday, over 1000 J/kg. Downburst and Microburst are the main concern as tall cores collapse. Some of the CAMs show a cold pool developing which could make a more widespread wind threat across NEPA. This is a more likely scenario given that we are on the edge of the large upper level ridge with storm coverage likely greater than what models have.

KEY MESSAGE 2...

The evolution of storms and rainfall today will help set the stage for potential flash flood risk Sunday evening into Monday. A broad, weak low moves slowly through the region with scattered showers and thunderstorms accompanying it. With the upper level ridge retrograding and surface high pressure across New England, an axis of stronger convergence is likely across portions of southern NY or Northern PA. HREF Probability Matched Means are indicating some higher end rainfall of 3 to 4 inches in 12 to 24 hours. This seems reasonable given forecast soundings show favorable winds for training (especially along that axis of convergence), and warm cloud depths 11K to 13K feet.

Heavy rain today, especially in areas that could get 1 to 2 inches of rain, would be more susceptible to the flash flood risk so a flood watch may be issued if the rain is widespread enough.

KEY MESSAGE 3...

The upper level ridge retrogrades to the west later this weekend and builds out west. Temperatures will be closer to average to slightly above, with surface dew points falling back into the 60s. This time of year, we do need to watch this northwest flow pattern. We are still close to the edge of the ridge, with decent low level moisture/instability each afternoon. Shear will be higher being closer to the jet stream so any shortwave that passes through could bring a threat for severe weather. Also, potential ridge riding MCSs would be possible under this flow.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Unsettled conditions this afternoon and evening as a cold front brings showers and thunderstorms to the region. Coverage, timing and the locations impacted remain uncertain, but mainly expecting the timing to be 19/20Z until 0/01Z. These storms could produce brief IFR conditions with gusty and erratic winds.

Later tonight, IFR fog will be possible, but the duration and thickness of the fog will be dependent upon where heavy rain from thunderstorms fall. At AVP, fog is more uncertain, so left it out of the forecast at this time.

Outlook:

Sunday afternoon through Monday...Restrictions possible due to showers and possibly thunderstorms.

Tuesday...Mainly VFR with a chance for showers and isolated thunderstorms.

Wednesday...Mainly VFR with a low chance for showers, mainly at ELM, BGM, and AVP.

Thursday...Restrictions possible with a passing frontal system producing more widespread showers and thunderstorms.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Heat Advisory until 8 PM EDT this evening for PAZ044-047. NY...None.