Marine Weather and Tide Forecast for Byram, CT

NEAR TERM /THROUGH FRIDAY/
Weak ridging in the mid and upper levels works in tonight supporting high pressure at the sfc. The high settles just to the immediate south and right nearby. This allows for radiational conditions to set up with light winds and mostly clear skies. Have continued with frost advisories for locations that get down into the middle 30s where the growing season has yet to end. Temperatures in the metropolitan area won't get as cold with more of a heat island influence, but surrounding locations will have patchy to even areas of frost. It will be one of the coldest night thus far, at least spatially where lows well to the north get down to around 30, with middle and upper 30s across much of the cast. The NYC metro will get down to around 40 or thereabouts.

On Friday the high pushes offshore by mid morning with a return flow attempting to get going. Guidance is suggestive of a weak return flow initially through midday, but later in the afternoon, especially towards and after 19-20z the pressure gradient increases as a S to SW flow picks up. Winds will likely get to 15 to 20 mph with gusts likely on the order of 25 to 30 mph closer to the coast, with lighter winds across the interior.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/
Mid levels clouds increase Friday evening with an approaching and progressive upper level trough getting into the Ohio Valley close to midnight. Some PVA takes places for the second half of the night along with some thermal advection in the lower to mid levels. This should eventually lead to light rain developing, mainly from west to east with an increase in PoPs taking place, especially after 03z.
With the upper level energy dispersed and not bundled cyclogenesis is expected to be rather weak and diffuse with the system being more of a frontal boundary or elongated area of lower pressure.
Essentially on and off light rain is expected for the second half of the night. Total QPF amounts into Saturday morning are only expected to be on the order of a tenth or two of liquid precip. With dew points inching up during the night on a SW flow temperatures will average well above normal with lower and middle 50s.

A pair of cold fronts is expected to pivot through during Saturday, with the first boundary moving through close to 12z for the city.
With the passage of this front most of the light rain is expected to end, although cannot completely rule out a few showers through late morning across eastern most sections as the weak secondary boundary and the main upper level shortwave pivots through. The winds will become more westerly and there really isn't colder air in the front's wake. It actually looks milder on Saturday by the afternoon with some downsloping on a W flow look for temperatures to get above average for this time of year and get into the lower and middle 60s.
Skies should generally clear for the late morning and into the afternoon.

Another series of shortwaves begin to approach Saturday night. The upper level pattern begins to amplify in response to these more potent shortwaves. Clouds will increase during the evening, and lower and thicken later at night. Much, if not all of Saturday night will feature dry conditions. Cannot completely rule out some light rain getting into far W and NW interior sections towards daybreak.
With the increase in cloud cover temperatures should average somewhat above average with lows mainly in the 40s to around 50.

LONG TERM /SUNDAY THROUGH THURSDAY/
Key Points:

* Rain remains likely much of Sunday and Sunday night with a low pressure pushing a strong cold front through the area. Residual rain showers or a mix of rain and snow is possible Monday night.
Much of midweek looks to be mostly dry.

* A strong cold frontal passage Sunday night will usher in the coldest air of the season for early next week. Widespread sub freezing temps likely inland Monday night, with temps not getting out of the 40s on Tuesday. Lowest wind chills will be mostly in the 20s Monday night, and middle 20s to lower 30s Tuesday night.

* Much of the period will feature a brisk and breezy W/NW flow, Monday through Thursday.

Several shortwaves rounding the base of a very large trough over Eastern Canada will result in the development of a very large and complex frontal system that is poised to impact much of the sensible weather of the next week.

A digging shortwave over the Great Lakes on Sunday will force a surface low to develop and push into the Northeast. Another more robust shortwave deepening the trough dives south out of Canada.
This deepening of the trough will slow the progression of the initial low pressure and result in separate areas of low pressure to develop along the initial cold front that will be positioned just off the East Coast into Monday. This forces a secondary cold frontal passage ushering in the coldest airmass of the season, peaking Monday night and Tuesday.

The very large low shifts back into Eastern Canada as the mid-level flow flattens out. High pressure builds south of the area through midweek. This will result in mainly dry conditions mid to late week, but also a persistent breezy W/NW flow as the area will remain between the low to the north and the high to the south.

AVIATION /20Z THURSDAY THROUGH TUESDAY/
VFR as high pressure gradually builds from the west. The high will build across tonight. It then retreats as our next frontal system approaches late tomorrow.

Winds are beginning to diminish and should be 10 kt or less by 00Z. Winds then become light and back SW overnight, VRB in spots.
Winds ramp back up tomorrow SSW 15-20 kt with gusts up to 25-30 kt.

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

Timing of winds diminishing this evening may be off by 1-2 hours in TAFs.


OUTLOOK FOR 21Z FRIDAY THROUGH TUESDAY

Friday night: Rain/MVFR cond likely, IFR possible. SW winds G15- 20kt.

Saturday: Rain ending, with VFR cond returning.

Sunday: Rain/MVFR cond likely, IFR possible. SE winds G20kt in the afternoon.

Monday: Mainly VFR. NW-W winds G15-20kt.

Tuesday: VFR. W winds G25-30kt.

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

MARINE
After small craft conditions this evening, especially for the more eastern waters, sub advisory conditions return on a diminishing NW wind. However, small craft conditions quickly return by early Friday afternoon. Marginal gale conditions are possible for at least a portion of Friday evening for the ocean and southern / eastern near shore waters. Sub advisory conditions should return quickly for the non-ocean waters into Saturday morning, with small craft seas remaining in place for much of Saturday morning for much of the ocean waters. Sub advisory conditions are then likely to return Saturday night.

Any sub-SCA conditions early Sunday morning will end as waves and winds increase to above SCA threshold on the ocean by Sunday afternoon. Winds may subside below 25kt for most of the waters into Monday but elevated waves on the ocean will allow SCA conditions to persist there. Other waters should remain below SCA thresholds through Monday. Increasing wind gusts Monday night may result in widespread SCA conditions on all waters through midweek. Gales are possible on the ocean zones Monday night into Tuesday.

HYDROLOGY
There remain no hydrologic concerns at this time through the entire forecast period.

TIDES/COASTAL FLOODING
Some coastal gauges will approach minor coastal flood benchmarks for the western south shore bays of LI, particularly some of the Nassau gauges for the mid morning high tide on Friday. Thus, a coastal flood statement has been issued for the Friday mid morning high tide cycle for So. Nassau. Similar water levels may get experienced for the Sunday late morning high tide for these same gauges and nearby gauges.

OKX WATCHES/WARNINGS/ADVISORIES
CT...Frost Advisory from midnight tonight to 8 AM EST Friday for CTZ009>012.
NY...Frost Advisory from midnight tonight to 8 AM EST Friday for NYZ071-078>081.
NJ...Frost Advisory from midnight tonight to 8 AM EST Friday for NJZ104-106-108.
MARINE...Small Craft Advisory until 8 PM EST this evening for ANZ331- 332-340-345-355.
Small Craft Advisory until 6 PM EST this evening for ANZ335- 338.
Small Craft Advisory until 10 PM EST this evening for ANZ350- 353.