Marine Weather and Tide Forecast for Brockport, NY

KEY MESSAGES
1) Increasing heat and humidity this week. Heat indices could reach the mid 90s by the end of the week.

2) Scattered showers and thunderstorms are expected to return mid- week.

DISCUSSION
KEY MESSAGE 1...Increasing heat and humidity this week. Heat indices could reach the mid 90s by the end of the week.

A ridge axis will move across the forecast area tonight through Tuesday. Warm air advection will strengthen through the day with mid to high level clouds spreading across the region. Temperatures will be well above normal Tuesday with highs in the mid to upper 80s, potentially hitting the low 90s across the lake plains and valleys in the Finger Lakes region. Lower temperatures are expected near the lakeshores.

As the ridge breaks down across the region Wednesday, increasing clouds and chances for showers and thunderstorms will bring maximum temperatures slightly down. Another ridge is expected to build into the region Thursday and temperatures at 850mb will likely climb to near +17C and the combination of warm and moist conditions may result in heat index values in the low to mid 90s. Confidence is low to medium as clouds and precipitation may inhibit the potential.
Heat headlines are possible for some locations across the area late in the week.

KEY MESSAGE 2...Scattered showers and thunderstorms are expected to return mid-week.

A shortwave trough will approach the region with warm, moist air spreading across the region Tuesday through Wednesday, increasing the potential for showers and thunderstorms. Initially, widely scattered showers and thunderstorms are expected to develop as increasing elevated instability moves into western NY Tuesday. Dry weather will likely continue east of Lake Ontario Tuesday. A surface trough is expected to move across the region Tuesday night, further increasing chances for showers and a few thunderstorms. This activity will likely taper off from west to east across western NY Wednesday while additional showers develop east of Lake Ontario.

A mid-level ridge within in a warm and moist airmass is expected to build into the region towards the end of the week. Weak impulses embedded in the flow around the ridge could support showers and thunderstorms through Friday. Shear profiles are expected to be weak through mid-week, with a slight uptick Thursday through Friday. The primary impact from any showers or thunderstorms will be heavy rain, as PWAT values are expected to exceed 1.5", which is above the 90th percentile for this time of year. Drier air is expected to move into the region for the start of the weekend.

AVIATION /00Z TUESDAY THROUGH SATURDAY/
Mainly VFR through the 00Z TAF cycle as surface high pressure over New England settles off the Northeastern coastline. A weakening shortwave trough will gradually encroach on the Great Lakes region from the west this evening through Tuesday. Mid/high cloud cover will increase tonight with a 5-10kt southerly flow, which will likely preclude fog development.

Mainly dry VFR weather to start the day Tuesday, though the added moisture and forcing with the approaching trough may cause widely scattered showers or an isolated thunderstorm west of KROC before 18z. Brief MVFR conditions cannot be ruled out in any showers that manage to develop.

Shower/thunderstorm coverage is then expected to increase and spread eastward thereafter into Tuesday evening.

Outlook...

Tuesday night...Mainly VFR deteriorating to MVFR/IFR with showers and a few thunderstorms.

Wednesday.. MVFR/IFR gradually improving back towards VFR from west to east. Diminishing chances for showers and thunderstorms across the western terminals.

Wednesday night through Friday...Mainly VFR with a chance of showers and thunderstorms. Localized lower flight CATs within any heavier showers or storms.

Saturday...Mainly VFR. Dry weather.

MARINE
High pressure settling off the Northeast coast will maintain winds 10-15kts or less across the lakes through Tuesday. Lake breeze circulations may lead to onshore flow and a small chop.

A weak passing wave of low pressure will cause winds to increase and begin shifting southwesterly late Tuesday night through Wednesday.
Winds around 15kts will be possible in this timeframe which will generate a chop on the waters, though wave heights are not expected to approach SCA criteria.

Light to modest west to southwesterly flow will then prevail Wednesday night through this weekend, which may support marginal SCA conditions at times.

Otherwise, the approach of several low pressure waves may generate a few thunderstorms over the lakes at times. The most probable timeframe for thunderstorms will be Tuesday night into early Wednesday.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...None.