Moriches Inlet NY to Montauk Point NY out 20 NM Marine Forecast
|Today...N Winds 5 To 10 Kt, Becoming Ne This Afternoon. Seas Around 3 Ft. Slight Chance Of Showers And Tstms Early This Afternoon. Chance Of Showers With Isolated Tstms Late.|
|Tonight...Ne Winds 10 To 15 Kt. Seas Around 3 Ft.|
|Sat...Ne Winds 10 To 15 Kt. Seas Around 3 Ft.|
|Sat Night...E Winds 5 To 10 Kt, Diminishing To Around 5 Kt After Midnight. Seas Around 3 Ft.|
|Sun...E Winds Around 5 Kt, Becoming S In The Afternoon. Seas Around 3 Ft.|
|Sun Night...Sw Winds 5 To 10 Kt. Seas Around 3 Ft.|
|Mon...W Winds 5 To 10 Kt, Becoming S In The Afternoon. Seas Around 3 Ft.|
|Mon Night...S Winds 5 To 10 Kt. Seas Around 3 Ft.|
|Tue...S Winds 5 To 10 Kt. Seas Around 3 Ft.|
|Tue Night...S Winds Around 10 Kt. Seas Around 3 Ft. Winds And Seas Higher In And Near Tstms.|
Area Forecast Discussion|
National Weather Service New York NY
512am EDT Fri July 3 2020
A backdoor cold front over central New England this morning will work from east to west across the area this afternoon into early this evening, followed by weak high pressure for the weekend. A weak frontal system approaches early next week and remains in the vicinity through the middle of next week.
.NEAR TERM Through Tonight
A potentially unsettled afternoon across the region as a backdoor cold front will work across the area, interacting with a moderate to highly unstable airmass. This coupled with highly anomalous PW values (Precipitable Water values) (above 90th percentile) nearing 2 inches raises the concern for heavy rainfall. Additionally, CAPES approaching 2000 J/KG north and west of NYC this afternoon also raises a concern for isolated severe thunderstorms. Weak shear, high CAPE environment would lend to pulse severe with wet microburst potential. Thus, Storm Prediction Center has maintained a marginal risk for the western half of the forecast area with the primary threat being damaging wind gusts (5 percent).
The global models support the axis of heaviest rainfall being across south central CT, with some westward progression into the Lower Hudson Valley. Closer to the coast, a somewhat more stable airmass with onshore flow developing this afternoon, lends toward lower amounts. Even some of the CAMs are supporting this solution. However, based on the axis of greatest instability and the progression of the cold front, it would seems to make sense for this axis to work into the Lower Hudson Valley and NE NJ. The 00Z NSSL WRF fits this scenario best with its evolution of the convection. Much of the area should see a quarter to half inch of rainfall, with amounts up to an inch inland with localized higher amounts. HREF members indicate a 45 percent chance of rainfall rates of 2 inches an hour. This has resulted in the whole area under a marginal risk (5 to 10 percent) for excessive rainfall with a smaller area under a slight risk (10 to 20 percent), which includes the Lower Hudson Valley, NE NJ, and SW CT.
Showers and thunderstorms will taper off from west to east late this afternoon (eastern sections) and far western sections this evening. Post-frontal clouds will linger through the overnight.
Highs today will get well into the 80s with even some lower 90s around the NYC metro. The coolest locations will be across SE CT and eastern LI due to the cold front working across these areas by late morning/early afternoon.
There is a borderline moderate risk of rip currents at the Atlantic Ocean beaches today due to a continued, but diminishing SE swell.
Short Term - Saturday Through Sunday
Expect a mainly dry 4th of July with a considerably cooler airmass in place with an easterly flow due to high pressure along the New England coast. Any post-frontal clouds in the morning will scatter out by afternoon. Highs Saturday will be in the upper 70s to mid 80s, which is close to normal.
High temperatures Sunday will moderate slightly. A dry airmass in place and a capping inversion should keep a lid on any convection.
There is low rip current risk at the Atlantic Ocean beaches on Saturday.
Long Term - Sunday Night Through Thursday
Another back door cold front approaches from the north Sunday night. There is uncertainty as to whether it actually will push south of the area. Regardless, the frontal boundary become stationary and remain in the vicinity through the middle of next week. This will bring chances for showers and thunderstorms starting Monday and continuing through next Thursday. This period will be characterized by typical summertime diurnal showers and thunderstorms as the frontal boundary appears to be weak with very Little forcing. Chances for precipitation are greatest during the day and lessen at night. In fact, Tuesday night may be dry for the entire forecast area as upper level ridging moves over the region and may provide enough subsidence to overcome the weak lift from the frontal boundary. However, a passing shower or thunderstorm could not be ruled out a this point during those time frames. Best chances for precipitation will occur away from the coast where the more unstable air will reside.
With ridging moving into the area and high pressure over the northern Atlantic at the surface, a warm and humid air mass will set up for at least Tuesday and Wednesday and possibly Thursday, setting up the first potential heat wave of the season. Highs will be in the upper 80s to lower 90s during this time frame, with the warmest readings expected across the New York City metro area and northeast New Jersey. Dew points will rise into the upper 60s to around 70 (and possibly even lower to middle 70s). This would translate to heat index values in the middle to upper 90s range, leading to possible Heat Advisories being issued. Wednesday and Thursday seem like the more likely days, with Tuesday possibly seeing more isolated heat index values of 95 to 99.
Conditions should remain below SCA (Small Craft Advisory) levels across all waters through the weekend with a weak low pressure system drifting across the eastern ocean waters and high pressure along the New England coast. Winds become northeasterly this afternoon 10-15 kts following a cold frontal passage and may gust up to 20kts for a short period Saturday afternoon across the ocean waters. Waves 3 to 4 feet over the ocean Saturday relax to 3 feet Sunday as winds become more southerly during the day.
Localized flash flooding is possible this afternoon into early this evening. Rainfall amounts will generally be an inch or less, with localized amounts exceeding 2 inches.
Tides / Coastal Flooding
The combination of a SE swell and increasing astronomical tides will bring waters levels across western Long Island Sound and the south shore back bays of western Long Island close to minor coastal flood benchmarks during the evening high tide cycles through the upcoming weekend. Based on Steven's NYHOPS-E being overdone the last few high tide cycles and considering it's coarser SNAP-Ex being better, preference remains toward a blend with the lower ETSS and ESTOFS. This brings water levels close to minor coastal flood benchmarks along the south shore bays of Nassau county this evening. Thus, a statement has been issued to address this potential. That being said, guidance all indicates a gradual uptick through the weekend due to the approaching full moon. Thus, there is the potential for a statement and/or advisory level tonight through Sunday. The south shore bays of western Nassau appear to be most susceptible.
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) is undergoing its final stages of testing, and is operating at full power.
NOAA New York NY Office: Watches - Warnings - Advisories
CT...None. NY...None. NJ...None. MARINE...None.