Area Forecast Discussion

WHAT HAS CHANGED

Issued a heat advisory for today for the Southern Tier and Finger Lakes Region. Urban valleys should see heat index values exceed 95 degrees for a few hours this afternoon.

KEY MESSAGES

1) Hot and muggy conditions are expected today and into the weekend.

2) Multiple systems are expected to move across the region through Friday, with thunderstorms. Some of the thunderstorms could be severe.

3) Cold front on Sunday will bring cooler conditions for the beginning of next week, but it also may kick off more severe thunderstorms as it passes.

DISCUSSION

KEY MESSAGE 1...

Hot and muggy conditions are expected today and a heat advisory has been issued for portions of the Southern Tier and Finger Lakes region. SW return flow will keep advecting in warm 850 mb temperatures of 15 to 20C and surface dew point temperatures climb into the 70s today. Leftover convective debris clouds could limit heating some, but still think that urban valley areas will see heat index values above 95F for a few hours this afternoon.

A front moves through Friday into Saturday, helping to lower dew points back down into the 50s and low 60s so while temperatures remain warm, the humidity will be much lower. Much cooler air will finally come by the start of next week, as a stronger cold front crosses the region on Sunday.

KEY MESSAGE 2...

A warm front lifting in to the region early this morning is producing thunderstorms across western NY and PA, but latest CAMs show this activity weakening and fizzling out before reaching our CWA. Still will have to watch for some convective development through the early morning hours, but the threat is low.

Later today, instability increases with mixed layer CAPE of 1500 to 2000 J/kg for much of CNY and into NEPA by later afternoon. A short wave pushes into NY later today and this should be enough to kick off storms again during the late afternoon and evening hours. Forecast hodographs are pretty strait, so damaging wind gusts are the main concern with any storms that fire. Weakening mid level lapse rates through the day will lower the hail risk and the lack of meaningful helicity also lowers chances of any spin ups.

The cold front will push through on Friday, with a line of storms likely developing along it. Mid level lapse rates will be steeper with shear increasing through the day. Hodographs are still looking fairly strait so strong wind gusts and some small hail are the main concern with the storms along the front.

KEY MESSAGE 3...

Drier air arrives this weekend, with Saturday still quite warm with highs in the 80s, but dew point readings fall back into the 50s. On Sunday, another cold front will push through the region. There are currently some timing differences with this feature, being it is still 4 days out. However, if the front arrives in the afternoon, then there will be some potential for more severe thunderstorms. At this time, models are showing high shear with 40KT+ of 0-6km bulk shear, but instability will be determined on the eventual timing of FROPA.

AVIATION /12Z THURSDAY THROUGH MONDAY/

LIFR fog at ELM and BGM this morning is expected to dissipate shortly after sunrise. IFR ceilings at AVP will gradually lift over the next few hours. Otherwise VFR conditions are expected through much of the day before showers and thunderstorms develop this afternoon. Thunderstorms approach from the west this afternoon into early evening. TEMPO groups for TSRA have been included at all TAF sites, with associated MVFR ceilings and visibilities. Confidence in exact timing and placement of thunderstorms remains low to moderate. Westerly winds will gust up to 15 knots this afternoon. Although, any thunderstorms that pass over a terminal could produce locally stronger wind gusts.

Outlook:

Thursday night through Friday Night...Scattered showers and thunderstorms may bring occasional restrictions, especially each afternoon.

Saturday into Sunday...Cold front moves through with VFR conditions likely, potential fog at ELM overnight.

Sunday afternoon and Monday... Showers return with MVFR restrictions possible.

BGM WATCHES / WARNINGS / ADVISORIES

PA...None. NY...Heat Advisory from noon today to 8 PM EDT this evening for NYZ015>018-022>025-055-056.