Moriches Inlet NY to Montauk Point NY out 20 NM Marine Forecast
|Overnight...S Winds 10 To 15 Kt. Seas 4 To 5 Ft. Scattered Showers With Patchy Drizzle. Patchy Fog. Vsby Less Than 1 Nm.|
|Mon...S Winds 5 To 10 Kt. Seas 4 To 5 Ft. Chance Of Showers With Patchy Drizzle In The Morning. Patchy Fog In The Morning With Vsby 1 To 3 Nm.|
|Mon Night...S Winds 5 To 10 Kt. Seas 4 To 5 Ft. Patchy Fog After Midnight With Vsby 1 To 3 Nm.|
|Tue...S Winds 5 To 10 Kt. Seas 4 To 5 Ft. Chance Of Showers. Patchy Fog. Vsby 1 To 3 Nm.|
|Tue Night...S Winds 10 To 15 Kt, Increasing To 15 To 20 Kt After Midnight. Seas 4 To 5 Ft, Building To 5 To 7 Ft After Midnight. Chance Of Showers In The Evening, Then Showers Likely After Midnight. Patchy Fog. Vsby 1 To 3 Nm.|
|Wed...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 6 To 8 Ft. Showers. Vsby 1 To 3 Nm.|
|Wed Night...Sw Winds 10 To 15 Kt, Becoming W 20 To 25 Kt With Gusts Up To 30 Kt After Midnight. Seas 5 To 7 Ft. Showers.|
|Thu...Sw Winds 15 To 20 Kt. Seas 5 To 8 Ft. Chance Of Showers In The Morning.|
|Thu Night...W Winds 10 To 15 Kt. Seas 5 To 7 Ft.|
|Fri...Sw Winds 5 To 10 Kt. Seas 4 To 5 Ft. Chance Of Showers In The Afternoon.|
|Fri Night...E Winds 5 To 10 Kt, Becoming Nw 10 To 15 Kt After Midnight. Seas 3 To 5 Ft. Chance Of Showers In The Evening.|
| 124 AM EDT Mon Sep 28 2020 |
Synopsis for the Long Island Waters and New York Harbor - ANZ300
High pres remains E of the waters today. A cold front approaches on Tue, and passes on Wed. Low pres impacts the waters Wed night and Thu. High pres builds towards the region on Fri.
| Area Forecast Discussion|
National Weather Service New York NY
130am EDT Monday September 28 2020
High pressure remains over the Atlantic today. A slow moving frontal system approaches from the Ohio Valley tonight into Tuesday, moving across the area Wednesday into Wednesday night. Waves of low pressure will move along the frontal boundary, bringing an extended period of unsettled conditions. A series of reinforcing cold fronts will then follow at the end of the week with high pressure returning next weekend.
Near Term - Until 6am This Morning
Included some dz for the overnight. Otherwise the forecast is on track. A weak surface low passing offshore as well as some positive vorticity advection aloft are giving some vertical forcing factors but the showers are generally very small and therefore very brief in duration. Winds generally are from the E-SE at around 5 to 10 mph, helping to advect in low level moisture as dewpoints are mostly in the upper 60s to near 70. With minimal temperature and dewpoints spreads along the coast, fog might become dense at times along the coast but the winds staying up slightly might help keep enough turbulence to prevent this from occurring and this is why the fog coverage was made patchy.
Short Term - 6am This Morning Through 6pm Tuesday
The shortwave shifts through the forecast area during the day Monday. Not as significant, but still present, is lift from a weak jet streak aloft. Cannot rule out showers at any given point of the day, but overall probably less of a chance towards late in the day as the sources of lift exit. Moisture is still shallow, so any shower activity will probably be light in intensity.
The high temperature forecast is a little challenging due to uncertainty surrounding how much the cloud cover dissipates during the afternoon. Thinking it will be similar to Sunday afternoon where it's partly to mostly cloudy with the higher cloud cover east of the city. Temps aloft will not have changed all that much as well. NBM was used for high temps, which best matches this thinking.
Lift remains on the weak side through Monday night, but will increase from the west late at night as PVA increases ahead of an approaching shortwave. Low chances of showers, and once again, patchy fog development.
There is a moderate risk of rip currents at the Atlantic Ocean beaches on Monday due to a building southerly swell and strengthening onshore winds.
Long Term - Tuesday Night Through Sunday
An unsettled Tuesday through the end of the week continues to become more likely as deterministic models and ensembles slowly come into better agreement. Differences arise with timing of specific features, but overall much needed rainfall is becoming likely Tuesday through early Thursday morning.
A longwave trough over the eastern CONUS with two separate shortwaves, one within the northern stream and one in the southern stream, will help draw up tropical moisture from the Atlantic and Gulf of Mexico. The longwave trough will only slowly pivot towards the east coast Tuesday into Wednesday, but will send a cold front towards the region. Several waves of low pressure will ride along the front, with the first coming late Tuesday through Wednesday morning. This wave will largely be associated with the northern stream trough and will help send the cold front into the region. The cold front then is likely to stall over or just to our east late Wednesday into Wednesday night. At the same time, the southern stream shortwave energy will quickly lift northward. This depicted by the GFS and ECMWF, which develop a deepening wave of low pressure that lifts along the Middle Atlantic and northeast coast into Thursday morning. However, there are some deterministic models (CMC, ICON) and members of the GEFS that are much quicker/drier. A blend of the GFS and ECMWF (European Centre for Medium-Range Weather Forecasts) were used in this forecast as they have been the most consistent the last several runs.
The most significant rain is expected late Tuesday into Wednesday morning and then again Wednesday night. Showers on Tuesday are likely to be associated with warm advection and increasing low level flow. More organized rain showers will then become widespread as large scale lift maximizes over a tropical air mass. Showers should diminish in coverage, and possibly end for a time later Wednesday afternoon before becoming widespread again with the second wave of low pressure Wednesday night. Conditions should dry out Thursday morning as the energy and low lift quickly to the northeast.
Rainfall amounts are a bit challenging as the placement of heaviest rain is still in question. Three quarters to an inch and a half is forecast Tuesday through Wednesday morning. Another inch to inch and a half is possible Wednesday night with a total on average around 2 inches. Locally higher amounts are possible in heavier rain. Due to the long duration of the event as well as very dry antecedent conditions and high flash flood guidance values, no significant flooding is anticipated. Minor urban and poor drainage flooding would be the main concern. There is some CAPE on soundings Tuesday afternoon/evening away from the coast, so have mentioned thunder here. Otherwise, have kept thunder out of the forecast.
Dry conditions briefly return late Thursday morning through Friday morning. A series of secondary cold fronts will move through the region. The longwave trough will also remain in place across the eastern states with its axis to our west. There are hints at another vort max within the trough moving towards the region on Friday. This energy may act upon the baroclinic zone just offshore to develop another low pressure. Differences are quite high among the guidance in its location and whether it develops offshore or closer to the region. Have capped Probability of Precipitation off at chance for the eastern half for now.
High pressure then builds into the weekend.
Above normal temperatures Tuesday and Wednesday will trend to near seasonable levels Thursday and Friday. Below normal temperatures are then expected next weekend.
There is a high risk of rip currents at the Atlantic Ocean beaches on Tuesday due to a southerly swell and strengthening onshore winds.
Swells have increased on the ocean a little more than guidance, so will go with a SCA (Small Craft Advisory) for elevated seas east of Fire Island Inlet tonight through Monday. It is possible however that waves are averaging below 5 ft across most of the zones at times. More confidence in waves staying below 5 ft Monday night. Winds now through Monday night will be on the lighter side, generally around 10 kt and onshore.
Seas build on the ocean Tuesday ahead of a slow moving cold front. Seas should then will be around or just above 5 ft Tuesday night and continue to build through Wednesday. Winds may also gust to around 25 kt Tuesday night into Wednesday as the cold front nears the waters. SCA (Small Craft Advisory) conditions may also occur late Wednesday night into Thursday on all waters as low pressure and the cold front move across the waters. Ocean seas may remain elevated through Friday, but winds should remain below 20 kt Thursday night into Friday.
A slow moving frontal boundary and several waves of low pressure will bring a significant rainfall Tuesday into early Wednesday and then again Wednesday night into early Thursday. Total rainfall amounts average around 2 inches with locally higher amounts possible. Due to dry antecedent conditions, the long duration of the event, and high flash flood guidance, no significant flooding is anticipated. Minor urban and poor drainage flooding is the main threat.
NOAA New York NY Office: Watches - Warnings - Advisories
CT...None. NY...None. NJ...None.
Small Craft Advisory until 6pm EDT this evening for ANZ350- 353.