Marine Weather and Tide Forecast for Alexandria Bay, NY

KEY MESSAGES
1) Increasing heat and humidity this week. Heat indices could reach the mid 90s Thursday and Friday.

2) Scattered showers and thunderstorms are expected through Friday evening.

DISCUSSION
KEY MESSAGE 1...Increasing heat and humidity this week. Heat indices could reach the mid 90s Thursday and Friday.

After a warm and humid day today, slightly cooler conditions are expected Wednesday as a westerly flow builds into western NY. Clouds and precipitation will keep conditions across the eastern Lake Ontario region cooler as well. Westerly flow will increase with wind gusts 20-25 mph across far western NY.

Increasing humidity is expected Thursday through Friday as another ridge builds into the region. Mean 850mb temperatures will climb near +18C and the combination of heat and humidity will support heat index values in the low to mid 90s. Heat headlines are possible for some locations during this time period, but confidence is lower with the potential for clouds and scattered convection.

Cooler and more comfortable weather are expected across the region behind a cold front this weekend.

KEY MESSAGE 2...Scattered showers and thunderstorms are expected through Friday evening.

An anomalously moist airmass will move into the region tonight.
Showers and thunderstorms will expand in coverage across the region, with heavy downpours as the primary impact through Wednesday morning. Due to dry antecendant conditions, the flood risk is low tonight. Coverage will decrease form west to east Wednesday, as subsidence and dryer air builds into western NY. A westerly flow will also stabilize areas east of Lake Erie. Showers and a few thunderstorms may form along the convergence of lake breezes south of Lake Ontario Wednesday afternoon. Profiles indicated an uptick in shear with an isolated risk of strong/severe storms, mainly across the Finger Lakes and east of Lake Ontario Wednesday afternoon. Any heavy showers or thunderstorms will produce heavy rain. There is a non-zero threat of localized flooding if training storms materialize.

A trough will deepen across the Great Lakes region Friday. A warm, moist airmass will reside ahead of an approaching strong cold front.
The combination of an increasing wind field and a unstable airmass will support the potential for strong thunderstorms across the region. Another risk from any heavy 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 /01Z WEDNESDAY THROUGH SUNDAY/
Mainly VFR through this evening with thickening and lowering mid level decks, although some brief MVFR conditions will be possible in scattered showers/isolated thunderstorms that develop from west to east through the evening hours ahead of a warm front slowly approaching from the west.

The warm front will slowly trudge east across the area tonight bringing deteriorating flight conditions. Mainly VFR flight conditions later this evening will deteriorate to widespread MVFR/IFR (LIFR interior Southern Tier) CIGS from west to east through the second half of tonight, with the worst conditions expected across the western NY terminals. An uptick in shower and isolated thunderstorm activity can also be expected with brief periods of MVFR/IFR within any heavier showers/storms.

Widespread IFR/MVFR CIGS will remain in place through midday Wednesday, while scattered showers and storms persist as a mid level trough encroaches from the west. As the mid level trough starts to exit the area Wednesday afternoon, so will the more widespread shower and thunderstorm activity across western NY, thus improvement back to VFR is expected from KROC westward through the second half of Wednesday. MVFR is expected to linger east of Lake Ontario through the end of the day.

Outlook...

Wednesday night through Friday...Mainly VFR with a chance of showers and thunderstorms. Localized lower flight CATs within any heavier showers or storms. Also, lower CIGS possible during the overnights (Wednesday night and Thursday night) across the higher terrain.

Saturday...Mainly VFR.

Sunday...VFR/MVFR with a chance of showers and thunderstorms.

MARINE
Southerly winds will slowly increase through tonight as pressure gradient tightens some between exiting high pressure to the east and weak low pressure to the west moving northeast through the central Great Lakes. Pressure gradient tightens a bit more Wednesday with winds veering southwest and increasing to 10-15 knots. Expect some light chop with waves two feet or less.

Expect light to moderate west to southwest breezes prevailing Wednesday night through this weekend, which may support marginal SCA conditions at times, especially during the daylight hours.

The passage of several waves of low pressure will generate a few thunderstorms over the lakes at times through the end of the work week.

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