Marine Weather and Tide Forecast for Groton Long Point, CT

KEY MESSAGES
1) Periods of showers with embedded thunderstorms through late this afternoon into early this evening. Rainfall will be heavy at times. A Flood Watch is in effect for northern New Jersey and NYC through early this evening.

2) High surf and high rip current risk expected for the ocean beaches through this evening.

3) Unsettled weather at times once again Wednesday and Thursday this week.

DISCUSSION

KEY MESSAGE 1
No big changes in the forecast today as an upper trough and associated surface frontal system interact with anomalously high precipitable water (PW). Much of the guidance, as is supported by latest mesoanalysis, support PW values falling just short of 2.5". This will not be too far off from the all- time high of 2.62" August 19, 1955.

00Z HRRR and WPC Urban Rain Rate Dashboard (URRD) show the peak rainfall window across the area this morning into early this evening. Both show about a 30 percent membership of hourly rainfall rates of 1"+. Once you go higher than that, the probabilities fall off to almost 0. That being said, the combination of a moisture-laden airmass along with large scale synoptic lift, points to several hours of moderate to heavy rainfall along with possible south to north training. As such, NYC was added to the flood watch for NE NJ. Elsewhere, 1-hour FFG is nearly 2 inches, so have held off. There could still be isolated instances of flash flooding outside the watch area. WPC still has most of the area under a slight risk of excessive rainfall.

Coverage will likely decrease from west to east this afternoon as the vertical wind profile begins to veer to the SW with drier air moving in. A cold front will then pass through late this afternoon into early this evening.

SPC also has the area under a marginal risk for severe weather with a 5% for the wind threat. Mid level lapse rates are generally less than 6c (weak), but there is moderate CAPE and decent vertical wind shear to support something isolated.

High pressure and dry weather is on tap for Tuesday.

Scattered showers and thunderstorms return Wednesday through Friday as the western Atlantic ridge retrogrades, sending the dissipating frontal boundary into the area.

KEY MESSAGE 2
Both Wavewatch and NWPS guidance have long period southerly swells of 8-11 ft 9s today which supports a high surf advisory for the ocean beaches and dangerous rip currents in the surf zone. Surf will range from 6 to 10 ft, highest across the Suffolk County ocean beaches.

There could be another high risk of rip currents for Suffolk ocean beaches Tuesday with otherwise a moderate risk of rip currents for the ocean beaches. For Tuesday, the winds will be decreasing to near 5-10 kt from northerly in the morning to more southerly in the afternoon. Ocean southerly swells decrease Tuesday to near 4 ft with near 7 second period.


KEY MESSAGE 3
Scattered showers and thunderstorms return Wednesday through Thursday as the western Atlantic ridge retrogrades, sending the dissipating frontal boundary into the area. PW values will close in on 2 inches. Localized heavy rainfall will be possible.

AVIATION /15Z MONDAY THROUGH FRIDAY/
A slow moving frontal system will impact the terminals into this afternoon. A cold front will pass through late this afternoon into this evening. High pressure briefly builds late tonight into Tuesday morning.

Showers/tstms with mostly MVFR cond expected, with pockets of IFR at times, especially for far eastern terminals. Coverage and intensity with tstms may be more sparse than fcst north/west of the NYC metros until late afternoon with the cold frontal passage.

S-SW winds gusting to around 20 kt mainly along the coast and for city terminals should shift NW, then N after cold fropa. Flight cats also quickly improving to VFR after fropa.

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

AMD likely for changing flight cats and tstms.

OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY

Tuesday: VFR.

Wednesday through Friday: MVFR or lower flight cat at times in showers/tstms. S winds 15-20kt on Thu.

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

MARINE
Small craft conditions are forecast for the ocean and some eastern non-ocean zones into this afternoon with south winds of 15 to 25 kt and gusts up to 30 kt. Highest winds will be across the eastern ocean waters. Challenge is how much of the winds aloft get down to the surface. A few gusts to 35 kt on the eastern ocean waters can't be ruled out. Small craft conditions will likely continue for the ocean through tonight as the winds veer more to the SW and seas remaining elevated around 5 to 7 ft. Sub advisory conditions should develop thereafter.

OKX WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...Flood Watch until 8 PM EDT this evening for NYZ072>075-176-178.
High Risk for Rip Currents until 9 PM EDT this evening for NYZ075- 080-081-178-179.
High Surf Advisory until 9 PM EDT this evening for NYZ075-080- 081-178-179.
NJ...Flood Watch until 8 PM EDT this evening for NJZ002-004-006- 103>108.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ331- 332-340-345.
Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353.
Small Craft Advisory until midnight EDT tonight for ANZ355.