Marine Weather and Tide Forecast for Hampton Bays, NY

KEY MESSAGES
1) Heavy showers and thunderstorms will bring the potential for flash flooding, mainly Tuesday afternoon through Wednesday morning. There is the potential for life threatening flooding during this time.

2) Potential for minor coastal flooding mid to late week with a coastal low.

DISCUSSION

KEY MESSAGE 1
A highly anomalous summertime pattern will feature the formation of an upper low late tonight into Tuesday, as shortwave energy drops southeast across the Lower Great Lakes into upstate NY. The associated surface low occludes and falls below 1000 mb. For this time of year, both the 500 mb and 1000 mb geopotential heights are near all time lows (well below the tenth percentile using the NAEFS). The combination of large scale lift and PWAT values increasing to around 2 inches is setting the stage for a significant rainfall event across the region. The heaviest axis at this time is forecast to be across NYC, NE NJ, and the Lower Hudson Valley, with 2 to 5 inches of rainfall. Localized higher amounts are possible. The 12Z HRRR shows a high neighborhood probability of 70%+ for an inch plus/hourly rates by Tuesday evening and 5 inch storm totals in this corridor by Wednesday morning. It also shows a significant signal for 3 inches/3 hours at 10 to 30 percent. While this may seem low, these probabilities are a good signal for high hourly precipitation rates. The WPC Urban Rain Rate Dashboard (URRD) is also showing significant support for these rates with some members of the ensemble supporting hourly rates with Annual Return Intervals (ARI) of 50 to 100 years. Bottom line, the ingredients are there for a potentially significant rainfall event. However there are likely to be some adjustments to this axis over the next 24 hours.

The rainfall will likely come in south to north oriented bands as advertised by the CAMs as energy rounds the upper low along with good upper level divergence. For much of Tuesday, these bands of showers and thunderstorms will likely be confined to the watch area, weakening as they pivot east. However, as the upper support and low level jet work east Tuesday night, the heavy rainfall will likely work across LI and southeast CT.
Guidance generally keeps total at 2 inches or less across these locations. However, there is the potential for higher totals and this area will have to be watched for possible expansion of the flood watch for Tuesday night into Wednesday.

The SPC marginal risk for severe weather on Tuesday gets just into southern portions of the NY/NJ metro. There is decent turning of the vertical wind profile with a 2 percent chance for tornadic development. LCLs are low and instability is marginal.
However. lapse rates are poor and deep convection supporting severe weather is unlikely.

Areas of showers with embedded thunderstorms will likely continue Wednesday into Thursday with the upper low tracking slowly east across the Northeast. The deep moisture will shift to the east and hourly rates will be significantly lower.

High temperatures will remain below normal during this time with the cloud cover and rainfall. Lows though will be closer to normal.

KEY MESSAGE 3
With the approach of a full moon midweek and an onshore E/SE flow with low pressure passing close by, minor coastal flooding is a possibility. There is still a fair amount of uncertainty at this time. Latest forecast brings some of the south shore back bay locations of LI and western LI Sound to just below minor coastal flood benchmarks during the evening/nighttime high tide cycles.

AVIATION /03Z TUESDAY THROUGH SATURDAY/
VFR through tonight, declining to MVFR or lower by late Tuesday.

Outside chance of a few early morning showers bringing brief MVFR conditions. Otherwise, isolated to scattered showers and thunderstorms develop into the afternoon, before a more widespread area of convection gradually works east over the terminals late afternoon into the evening. IFR cigs possible.
Any thunderstorm could produce wind gusts above 40 kt and large hail. The showers likely persist into Tuesday night.

Generally, S/SE under 10 kt through tonight. S/SE gusts near 20 kt develop into Tuesday afternoon.

...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Low chance of spotty shower or drizzle Tue AM could lead to brief MVFR conditions.

Timing of SHRA/TSRA onsets could be off by a couple of hours. Any thunderstorm could produce wind gusts above 40 kt and large hail.

Amendments likely on Tuesday for changing categories.

OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY

Tuesday Night: MVFR or IFR in SHRA/TSRA, S-SE winds G15-20kt.

Wednesday: Mostly MVFR/VFR conditions likely with showers.
Thunderstorms and brief IFR possible.

Thursday: MVFR or lower possible. Showers possible and a slight chance of a thunderstorm. N-NW wind G15-20kt.

Friday: Mainly VFR, chance of an afternoon shower or tstm.

Saturday: Mainly VFR.

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

MARINE
A slow moving low pressure system will bring Small Craft Advisory conditions to the waters starting Tuesday afternoon. Gusts are forecast to peak around 25 to 30 kt Tuesday evening through Wednesday morning and ocean seas peaking at 5 to 6 ft Tuesday night through Wednesday. There is still some uncertainty with exact low track and strength of winds.

Thereafter, the pressure gradient looks to decrease and sub SCA conditions are then expected through the weekend.

Rip Currents...

A moderate risk for rips at all beaches on Tuesday, though it's borderline high in the later afternoon as swell builds in. Winds 10-15kts and increasing by later afternoon. RCMOS has maintained a mainly moderate risk, perhaps in part due to the later arrival of swell.

A high rip risk then is in store for Wednesday, with surf heights near 5 ft, and increasing southerly swell at 7-8s.

OKX WATCHES/WARNINGS/ADVISORIES
CT...Flood Watch from 8 AM EDT Tuesday through Wednesday morning for CTZ005-006-009-010.
NY...Flood Watch from 8 AM EDT Tuesday through Wednesday morning for NYZ067>075-176>179.
NJ...Flood Watch from 8 AM EDT Tuesday through Wednesday morning for NJZ002-004-006-103>108.
MARINE...Small Craft Advisory from 6 PM Tuesday to 2 PM EDT Wednesday for ANZ331-332-340.
Small Craft Advisory from noon Tuesday to 6 AM EDT Wednesday for ANZ335-338-345-355.
Small Craft Advisory from 6 PM Tuesday to 3 PM EDT Wednesday for ANZ350.
Small Craft Advisory from noon Tuesday to 2 PM EDT Wednesday for ANZ353.