Marine Weather and Tide Forecast for Upper Nyack, NY

KEY MESSAGES
1) A period of moderate to heavy rain and embedded thunderstorms likely Sunday afternoon into Sunday Night, with additional scattered showers and thunderstorms possible Monday with passage of frontal system.

2) Isolated to scattered showers with strong wind gusts possible this afternoon into early evening. Otherwise, lowering humidity with seasonable temps through Saturday.

DISCUSSION

KEY MESSAGE 1
Good model agreement in confluent upper flow over the region Sunday into Monday, with a strong northern stream shortwave sliding east through central Quebec. At the surface, low pressure tracks ENE through central Quebec, with associated frontal system approaching the region on Sunday and crossing through Monday.

Primary threat appears to be for a period of moderate to heavy rainfall Sun aft/night with approaching shortwave lift and developing 30-40kt llj lifting Atlantic and sub-tropical PAC moisture (2-2.5" PWAT) ahead/along approaching warm front w/ likely triple pt wave. Still quite a bit spread on exact track of this triple point low to the north, over or to the south of the region. A track across or just south of the region would likely bring the heaviest rain threat, with enhanced moisture convergence.

Overall medium range NWP and AI ensembles are not bullish in terms of QPF for an excessive rainfall event, but with the above mentioned factors the flash flood threat will be in the mesoscale details. Iso-sct flash flood potential exists with combo of modest forcing/ focus of a very moist, sub- tropical, weakly unstable airmass, conditional on warm front/triple pt low traversing the area.

A low track over or to the north of the region would present a low and isolated strong to severe threat in high shear/helicity weak surface instability environment. Low predictability on thunderstorm coverage and severity at this time.

Additional iso-sct shower and thunderstorm activity possible Monday aft/eve with trailing slow cold frontal passage.


KEY MESSAGE 2
Mean NE US troughing continues through Saturday, with a couple of vigorous shortwaves and associated cold fronts passing through this evening and Saturday afternoon.

Iso-sct low top shower potential with shortwave/cold frontal passage late today/this evening, particularly across SE CT. Instability is mainly below the mixed phase region limiting threat for thunderstorms to slight. Any heavier shower or thunderstorm will have potential to bring down some strong wind gusts (40-50 mph)
with strong deep layer uni-directional wind shear, downward momentum transfer favoring wind profile, mid-level dry-air entrainment, and steep low- level lapse rates.

Environment continues to dry heading into the weekend, which should limit shower potential from shortwave/cold frontal passage Saturday afternoon.

Progressively lower T and Tds expected today and Saturday in wake of these frontal passages.Temperatures will run near seasonable today (mid 80s NE NJ/NYC metro and lower 80s elsewhere), then slightly below seasonable on Saturday as Canadian high pressure builds in.

AVIATION /15Z FRIDAY THROUGH TUESDAY/
High pressure builds over the terminals through Saturday, with a weak surface trough/cold front passage this evening.

VFR through the TAF period. An isolated shower or thunderstorm possible late this afternoon and early evening, especially across southeast CT terminals towards KGON. KGON has VCSH for this evening to indicate this potential. Too low probability elsewhere to put any mention of SHRA in other TAFs.

NNW-NW flow into early afternoon will back to the WNW and potentially W towards late afternoon. Some coastal terminals will likely sea breeze in the afternoon, especially KJFK, KISP, KBDR, and KGON. Wind speeds will be under 10 kts morning, then around 10 kts this afternoon into early evening. Winds lighten this evening back to less than 10 kts, then shift to the N-NE late tonight.

NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of sea breeze passage at KJFK may be off by an hour.

A sea breeze may approach KEWR this afternoon and could bring S-SE winds, but speeds will be under 10 kt.

Variability in wind direction likely around 00z before settling to the N-NE 02z-04z

OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY

Saturday: Mainly VFR.

Sunday: VFR into the afternoon. Showers and a few thunderstorms possible with a chance of MVFR or lower conditions late in the day and at night. S winds G15-25kt, highest at the coast.

Monday: Mainly VFR. Chance for showers and a few thunderstorms early and mainly east of NYC metro terminals. Isolated shower possible in the afternoon.

Tuesday: VFR.

Detailed information, including hourly TAF wind component forecasts, can be found at: https:/ www.weather.gov/zny/n90

MARINE
Sub-SCA conditions anticipated through Saturday night in a weak pressure regime.

SCA potential increases Sunday afternoon into Sunday Night for ocean waters, and potentially all waters with strengthening southerly flow ahead of approaching frontal system.

Rip Currents: A couple of 1 ft S/SE onshore swells, with weak seabreeze development will generally keep the rip risk low today. Similar swells conditions with 1-2 ft longshore wind waves will once again result in a low rip risk on Saturday.
Recent new moon will continue the wide tidal range, and could increase rip risk to moderate particularly around the times of low tide each afternoon.

Rip current risk likely building to high on Sunday with strengthening southerly winds and southerly winds waves building to 4-5 ft.

OKX WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...None.
NJ...None.
MARINE...None.