textproduct: Binghamton

WHAT HAS CHANGED

A Tornado Watch has been issued for counties along and east of I-81 until 9pm.

Adjustments were made to PoPs to better represent current precipitation and expected evolution through this afternoon.

KEY MESSAGES

1) Several rounds of showers and thunderstorms are expected this afternoon and evening. Some of the thunderstorms may contain gusty to damaging winds and heavy rain.

2) Showers will linger into at least the first half of Wednesday. High pressure returns for the rest of the week, with very pleasant weather conditions expected.

DISCUSSION

KEY MESSAGE 1...

***UPDATE***

Low level wind shear along a warm front over the area is allowing for increased tornado chances across eastern portions of the CWA. Several tornado warnings have been issued in the past 30 min, with 1 report of a tornado. Because of this, a Tornado Watch has been issued.

--- Complicated setup today with many factors playing into thunderstorm development and severe storm chances.

A strong shortwave trough moving into the western portion of the area is driving the development of scattered showers and storms. Cirrus blow off from storms earlier over OH has limited the instability over this region, allowing for a few weak storms but mostly just periods of moderate to heavy rain. East of this area, we have seen more breaks in the clouds which has allowed stronger CAPE to develop, with values above 1000 j/kg currently growing from a N/S line bisecting the the Central Finger Lakes and to the east. 0-6 bulk shear values are currently in the 35-40kt range and should remain around this range through the afternoon hours thanks to the strong shortwave overhead. With the current storms moving into a much more favorable environment, we expect some of the storms to grow and become severe, with damaging winds and heavy rain and tornadoes will be the main threats as the afternoon progresses. Hodographs show tornadic signatures, with multiple swirls located along a line of storms moving into Otsego, Delaware and Sullivan counties. Tornadoes will be possible as these storms develop through the afternoon hours.

Guidance suggests we may have a brief lull in activity late this afternoon and early evening. This would bring a potential for some clearing that could reinforce some early evening surface instability. At the same time, a 2nd shortwave currently over eastern MI is progged to track over the region. This synoptic lift combined with surface instability and increased 0-6km shear of 40-50kts would allow for more severe storms to develop. The big question is will we get enough clearing to introduce sufficient CAPE. If we do not and the CAPE remains under 1000 j/kg, the amount of severe storms would be lower but severe chances will remain given the high shear values and synoptic lift provided by the transiting shortwave.

Heavy rains will also accompany these storms, allowing for a potential for isolated flash flooding where multiple rounds of storms impact an area. Currently, NEPA has a heightened chance for isolated flash flooding with storms currently rolling through and the expected 2nd round of storms later this afternoon and evening.

The severe threat looks to end late this evening. Scattered rain showers are going to linger through the night, especially north of the Southern Tier as the trough axis moves over the area.

KEY MESSAGE 2...

With the trough lingering overhead into Wednesday, we expect some scattered light rain showers to remain streaming across the area.

After the trough axis moves east of the area, cool Canadian air is expected to move into the region and plant itself through the rest of the work week as high pressure dominates the weather pattern. Wednesday will be the coolest, with highs in the upper 60s to mid 70s. We will see a slight warming trend through the rest of the week, with low to mid 80s by the weekend. Showers and storms may return Sunday or Monday as a trough tries to work its way into the region, but it will depend on if the ridge overhead weakens or flattens enough to allow for precip to move in.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Scattered showers and thunderstorms are expected across the area this afternoon and early evening. Tempos were added at each TAF site for IFR/MVFR thunderstorms, generally from 19-23z or 00z. BGM is already getting a heavy thunderstorm, but this will move away between 18-18:30z. Also added in PROB30 groups at RME, SYR and ITH in the 23z to 03/04z timeframe for a possible second round of thunderstorms, with restrictions as the next front pushes in from the northwest.

After the bulk of the showers and thunderstorms move east of the area in the mid to late evening, a deck of lower clouds is expected to move in and result in at least MVFR restrictions (mainly after 03Z). IFR restrictions will be possible late tonight/early Wednesday morning at some of the TAF sites (RME, and perhaps AVP).

Winds will generally be south-southwesterly throughout the TAF period. Winds will be around 10kts and occasional gusts up to 20kts this afternoon. Locally higher gusts are possible in any thunderstorms.

Outlook:

Wednesday Afternoon...Lingering ceiling restrictions possible; otherwise becoming VFR.

Thursday through Sunday...Mainly VFR; morning fog at KELM may result in restrictions.

BGM WATCHES/WARNINGS/ADVISORIES

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