textproduct: Binghamton

WHAT HAS CHANGED

There has been a modest increase in potential for thunderstorms for at least the Finger Lakes area late Wednesday, but uncertainty for how far south and east it will go from there.

KEY MESSAGES

1) Despite a cool dawn, warming will get underway today and then peak on Wednesday.

2) A front moves in late Wednesday into Thursday bringing rain and a chance of thunderstorms to parts of the region, a few of which could be gusty.

3) Generally dry benign weather returns towards the end of this week, with temperatures bumping back up over the weekend.

DISCUSSION

KEY MESSAGE 1...

Dry weather will continue today through most of Wednesday, with warming as we get on the back side of high pressure. That surface high is in charge currently, with radiational cooling yielding a fairly chilly start to the day with upper 40s-mid 50s around dawn. Ridging is getting underway aloft, but will take longer at the surface as the high slowly edges east and thus dewpoints will still be comfortable this afternoon. Sun will be mixed with scattered mid-to-high level clouds, but will still manage to help temperatures reach well into the 70s; a few lower elevation locations even near 80.

The high exits more decidedly overnight, making way for increasing southerly to southwesterly warm air advection. Thus it will not be quite as cool tonight with lows of mid 50s-lower 60s. Dewpoints will also be noticeably on their way up, reaching mid-upper 60s to cause a muggy feel. Temperatures have also trended a touch higher in latest guidance since we will spend all day in the warm sector of the incoming system with at least partial sunshine. Highs of upper 70s-mid 80s could easily feel another few degrees higher given the humidity.

KEY MESSAGE 2...

Canadian low pressure will trail a cold front through our region late Wednesday into Thursday. With models trending just a touch warmer ahead of the front and thus a little more instability, there has been a small uptick in potential for thunder Wednesday afternoon at least to our west. Ensemble probabilities carry this into the Finger Lakes Wednesday evening, with potential for a few to several hundred J/kg of Convective Available Potential Energy (CAPE) along with decent 30-40 knots of shear in much of the lowest 6km. However, nocturnal timing for the front itself leads to doubt for how far southeast the thunder can manage to reach. Regardless, given the amount of shear, a conditional potential for a few gusty cells has to be considered and indeed the Storm Prediction Center recently introduced a Marginal Risk of Severe Thunderstorms for roughly the Twin Tiers northward, centered over the Finger Lakes.

Precipitable Water Values will pool along the approaching front to beyond 1.75 inches across the Central to Eastern Great Lakes. The front looks to be fairly progressive as it moves through so training thunderstorm threat is lowering. That said, heavier rainfall rates in some thunderstorms could lead to brief localized urban/poor drainage water issues if occurring over a town or city Wednesday evening, with northern Finger Lakes to NY Thruway Corridor a little more prone to that compared to areas south. Frontal progress will slow somewhat on Thursday, being so far from the parent low and also starting to get more flow- parallel. This will keep a chance of showers and perhaps thunder going mainly south of the Twin Tiers.

KEY MESSAGE 3...

High pressure a brief shot of cool air advection should yield a window of Fall-ish weather Thursday night into the first part of the weekend, similar to what we recently experienced. However, with a fast moving zonal pattern aloft, the high will pass quickly to allow warming to return over the weekend. Forecast temperatures of 70s to near 80 are figured for Saturday and Sunday. That said, moisture will remain quite limited, and thus passing yet-to-be-resolved waves embedded in the flow do not have very high odds of producing rain. So for now, chances for showers Saturday night onward are still only in the 20-40 percent range.

AVIATION /03Z TUESDAY THROUGH SATURDAY/

High pressure will center over the area tonight and clouds will mostly clear out this evening with VFR flight conditions expected. Some higher clouds, currently near the upper lakes will try to fill- in overnight, but should remain at the higher levels. With mainly clear lower levels and light to calm winds, fog can be expected again, especially at the favorable spots (ELM & ITH) with BGM having some fog at the lower elevations from the terminal that may get close to the runway. Fog will cause lowered CIGs & VSBYs, likely down to LIFR at times for the more favorable locations.

Mainly VFR tomorrow with lower cats early due to morning fog. Sounding profiles are a little drier in the lower levels than previous days, so the fog may burn off a bit quicker Tuesday morning.

Winds this evening and tomorrow will remain near or below 5 mph out of the northwest to northeast or variable.

Outlook...

Tuesday night...Mainly VFR; areas of low clouds and fog possible.

Wednesday through Thursday...Potential cold front passage with wind shift and showers. Highest chance for showers later Wednesday through Thursday morning.

Friday through Saturday...Mainly VFR with high pressure building into the region. Morning fog will be possible.

BGM WATCHES/WARNINGS/ADVISORIES

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