Marine Weather and Tide Forecast for Geneva, NY

KEY MESSAGES
1) High pressure pressure remains in place through the start of the weekend.

2) A low pressure system will move through Sunday and Sunday night.
There will be potential for heavy rainfall.

3) High pressure returns midweek with a stretch of quieter weather, though the next system will move through late next week.

DISCUSSION
KEY MESSAGE 1...

An upper level disturbance will move through this afternoon and kick off isolated showers. Instability is expected to be limited with MLCAPE values less than 500 J/kg though 0-6 km bulk shear will be 50 to 60 kts, so a few thunderstorms will also be possible. We may have to monitor how the environment evolves this afternoon because if instability increases higher than modeled, then there would be potential for strong, pulse-like convection. The best chances will be east of I-81 in central NY.

Surface high pressure builds into the region later today. This high will remain in place through Saturday, extending the period of dry and pleasant conditions for most. Tonight, skies will become partly to mostly clear and winds will be calm so fog is expected to develop.
Temperatures will fall into the 40s and 50s overnight before bouncing back into the 70s and 80s on Saturday. Saturday night will have similar conditions as tonight, though may be a touch warmer for some as cloud cover increases ahead of the next system. There is a low chance for showers over far western portions of the region, though most guidance holds off until Sunday.

KEY MESSAGE 2...

The ridge of high pressure will break down on Sunday. A surface low will deepen slightly as it moves across the lower Great Lakes region. Some showers ahead of this system will be possible by Sunday afternoon, though the bulk of the precipitation will be later in the day through Sunday night. PWATs will increase to 1.75 to 2 inches, and there will warm cloud depths of at least 10,000 feet. These conditions will favor heavy rainfall. The one plus will be this system is expected to move along fairly quickly and the potential for training showers is low. Despite this, models are showing localized precipitation accumulations of 1 to 3 inches with most guidance favoring the bulk of rain over northeast PA. This lines up well with WPC's thinking and the ERO Slight Risk clipping the Wyoming Valley. There does remain uncertainty on where the heaviest rainfall will indeed fall and how much there will be. This drier stretch has allowed soil conditions to dry out some, so urban and poor drainage areas are where localized hydro issues will be most likely. Models have backed off on on instability over the region, so stronger storms are not expected. NBM guidance maintains low chances for thunder, which if showers move in later, that would allow for some instability to develop. Lingering moisture behind the system will support additional rain showers on Monday. PWATs will significantly decrease by then, so these showers will be light.

KEY MESSAGE 3...

High pressure builds into the region on Tuesday, though some models keep the lingering showers around into the morning. Otherwise, conditions will be dry through a period of time with a slight warming trend. The next system with widespread rain chances will then move in by Thursday, though uncertainties remain. Guidance like the GFS have an open wave moving through while the ECMWF has a closed low. There are timing differences as well with the GFS being much quicker than most other guidance.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
Mainly VFR through the TAF period. We maintained the PROB30 group at KRME for a few passing showers and thunderstorms this afternoon. Patchy fog possible overnight again with the highest potential at KELM, where a TEMPO group for IFR conditions expected.

Outlook...

Saturday...Mainly VFR. Areas of low clouds or fog and associated restrictions possible early morning.

Sunday...Restrictions likely with showers. Some thunderstorms possible in the afternoon/evening hours.

Monday...Chance of showers and afternoon thunderstorms, restrictions possible.

Tuesday and Wednesday...Mainly VFR. Some potential for early morning fog and/or low cloud restrictions.

BGM WATCHES/WARNINGS/ADVISORIES
PA...None.
NY...None.