Marine Weather and Tide Forecast for Mystic, CT

KEY MESSAGES
1) Showers with potential thunderstorms late this evening into a portion of Monday morning may produce locally heavy downpours. Minor urban and poor drainage flooding is the main concern, but cannot completely rule out a localized flash flood risk close to the coast.

2) Dry with near normal temperatures Tuesday and Wednesday before the next chance of showers or thunderstorms Wednesday night into Thursday.

DISCUSSION

KEY MESSAGE 1
A concentrated area of showers approaching from the west should push into the western zones toward the end of the afternoon, but a few stray showers ahead of it may pass through. No thunder is expected at least through the early evening with limited instability.

Afterwards, a warm front makes its closest approach to the southern portion of the area late tonight into Monday morning. A weak wave of low pressure is still progged to develop along the warm front and then move over or just south of the area late tonight through Monday morning. This will support the development of showers and possibly a few thunderstorms. Instability should increase somewhat, but will be dependent on how far north the warm front and the resulting track of the low. If the low and front remain south of Long Island, showers may end up mostly on the moderate side with perhaps an isolated thunderstorm/heavy downpour, mainly confined to the southern half of the area. If the low and front end up farther north over or just north of Long Island, showers and a few thunderstorms could be locally heavy at times, especially across portions of the NYC metro, Long Island, and southern CT. Based on 12z Global and hi-res models, it appears that low center will track over or just off the south shore of Long Island, leaning towards the second scenario. With that said, WPC has shifted the marginal risk of flash flooding towards the SW and out the forecast area from the previous outlook. It now just borders the SW zones, so the flash flooding threat appears to be very low. PWATs should be able to climb to 2.00-2.25 inches.
However, limited instability should prevent anything more than minor/urban poor drainage flooding, but still cannot completely rule out a localized flash flood risk (noting still some decent llj forcing). The risk of any localized flash flooding would most likely end up late tonight/Monday morning when the warm front/low pressure center, llj and associated upward forcing are closest to the area.
Average rainfall amounts range three tenths across interior CT and the Lower Hudson Valley to one half to three quarters most elsewhere. An inch is possible across parts of Long Island. Locally higher amounts cannot be ruled out in any heavier downpours.

Severe thunderstorms are not expected through the entire event due to the anticipated limited instability. However, will have to watch near and along the warm front/low pressure center late tonight/Monday morning if instability and shear were to increase more than currently forecast.

Any lingering showers across E Long Island and SE Connecticut should end by the end of Monday morning. A trailing cold front/surface trough will move across the area late in the day, which may be enough to support scattered shower and isolated thunder development.
The higher probability (chance) resides inland and across NE NJ and NYC metro. Cannot rule out a brief locally heavy downpour. Farther east, the chances are much lower due to subsidence immediately behind the passing low pressure center.

KEY MESSAGE 2
High pressure will build over the area through the middle of the week. This will lead to dry conditions and seasonably warm temperatures Tuesday into Wednesday. Models continue to come into better agreement with the next shortwave trough and associated cold front moving over the northeast late Wednesday night into Thursday.
Much of the energy and lift may pass well to the NW, limiting potential for showers/thunderstorms. However, there is still some ensemble spread which is captured well with the NBM. PoPs increase late Wednesday night and continue in the chance range through Thursday afternoon.

Uncertainty is much higher for the end of the week/start of next weekend. High pressure may build over the northeast, but the front that moves through Thursday may stall to our south. Some of the guidance hints at a few waves of low pressure riding along the front. It remains to be seen if any unsettled weather will occur heading into next weekend. The current NBM precip probabilities indicate a slight chance on Friday and Saturday.

AVIATION /20Z SUNDAY THROUGH FRIDAY/
High pressure moves offshore as a frontal system approaches from the west this afternoon. The frontal system impacts the terminals late this afternoon through Monday morning.

VFR through much of the day. Chances for MVFR increase late this afternoon, mainly after 21Z, into this evening along with the chance for showers. MVFR and SHRA will continue through tonight. IFR is likely for more outlying terminals, especially after 6Z, with less confidence for the NYC terminals. Indicated this uncertainty in a PROB30 for the NYC terminals. SHRA ends early Monday morning from 13-16Z, however MVFR/IFR cigs will continue into Monday morning and possibly into early afternoon.
More outlying terminals may remain IFR/MVFR through the day Monday. Low confidence of thunder and will leave out of the TAF.

Winds increase out of the S this afternoon at around 10-15kt with gusts from 20 to 25 kt, mainly along the coast, into the evening and possibly overnight. Winds will shift to the west and then northwest after 12-15Z Monday, later at eastern terminals.

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

Timing of gusts and MVFR could be off by a few hours compared to TAF.

Timing of showers could be off by a few hours compared to TAF.

OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY

Monday Afternoon: MVFR possible with the chance of additional showers and thunderstorms in the afternoon and early evening.

Tuesday: VFR.

Wednesday: Mainly VFR. Chance for showers and MVFR at night. A slight chance of thunderstorms. Southerly wind gusts 15-20 kt afternoon into early evening.

Thursday: A chance of showers with MVFR possible. Otherwise, mainly VFR.

Friday: Mainly VFR. MVFR possible in any SHRA.

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

MARINE
S flow gradually increases tonight. This will yield potential for 25- 30 kt wind gusts on NY Harbor, ocean, and south shore LI Bays where a SCA remains posted. Winds on LI Sound and eastern LI Bays should remain just below SCA levels, but a gust or two to 25 kt will be possible. 25 kt wind gusts then likely linger on the ocean for a portion of Monday. Seas will also build into this evening, reaching 4-7 ft late tonight into Monday morning. Seas subside Monday afternoon and evening. Conditions will then remain below SCA levels Monday night through Friday with a relatively weak pressure gradient in place.

Rip Currents: The rip current risk thru this eve is moderate as S winds continue to increase. There is a high risk on Monday, although wrn beaches could improve significantly by late mrng or early aftn with winds shifting and diminishing. The risk on Tuesday is moderate due to a lingering sely swell.

OKX WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...High Risk for Rip Currents from Monday morning through Monday evening for NYZ075-080-081-178-179.
NJ...None.
MARINE...Small Craft Advisory until 4 AM EDT Monday for ANZ338.
Small Craft Advisory from 11 PM this evening to 8 AM EDT Monday for ANZ345.
Small Craft Advisory from 11 PM this evening to 4 PM EDT Monday for ANZ350-353.
Small Craft Advisory until 11 AM EDT Monday for ANZ355.