New York Harbor Marine Forecast
|Today...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming W 5 To 10 Kt This Afternoon. Waves 1 Ft Or Less. Chance Of Showers And Slight Chance Of Tstms Late This Morning, Then Showers And Chance Of Tstms This Afternoon. Vsby 1 To 3 Nm.|
|Tonight...N Winds 5 To 10 Kt. Waves 1 Ft Or Less. Chance Of Showers In The Evening.|
|Wed...N Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Wed Night...Ne Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Thu...Ne Winds 5 To 10 Kt, Becoming E In The Afternoon. Waves 1 Ft Or Less.|
|Thu Night...S Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Fri...S Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Fri Night...Sw Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Sat...N Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Sat Night...Ne Winds 5 To 10 Kt. Waves 1 Ft Or Less. Winds And Waves Higher In And Near Tstms.|
|Area Forecast Discussion|
National Weather Service New York NY
1030am EDT Tuesday September 18 2018
Synopsis: The remnants of Florence will pass through the region this morning, followed by a cold front this afternoon. High pressure then ridges down southeastern Canada through Thursday, then retreats to the northeast Thursday night. A cold front approaches from the west on Friday, then crosses the area Friday night, followed by high pressure building in for the weekend into early next week.
Near Term - Through Tonight
Main change this morning was increasing chances for flash flooding this afternoon. Flash flood watch for the Lower Hudson Valley, Northeast NJ, Western Long Island, and Southwest CT including NYC from 11AM until 7PM. This is a combination of where heavy rain occurred during the previous day and where heavy showers and thunderstorms are expected this afternoon. This includes the highly urbanized portions of the region and these areas are where many mesoscale models are showing a heavy line of showers and thunderstorms moving across this afternoon. While these heavy showers and thunderstorms are still expected even for easternmost portions of the region (namely Southeast CT and Suffolk County NY), these portions of the region have higher flash flood guidance so flooding would be more minor nuisance flooding.
The remnants of Florence lift to the northeast this morning followed by a 850-500 hPa trough passing this afternoon.
Instability is increasing per LAPS, and will continue to do so until the surface trough/cold front passes this afternoon. The position of the main low, tracking roughly along the Mass Pike, will keep the best directional shear north of the area. As a result, severe thunderstorms are not expected, although the mesoscale environment will continue to be monitored through the day.
Pops were updated to reflect faster end time of High resolution models and the 6Z runs of NAM and GFS. Expect precipitation to be done across most of the Tri-state by 6pm, with the entire area in the clear by 8pm.
Southerly flow this morning with the low level jet should produce the strongest gust potential through 15-17z. The surface trough coming through then lightens wind as it progresses across the CWA. Light wind fields behind the front with winds up to 850 hPa maxing out at 20 kt.
A blend of the mos was used for temperatures today and tonight.
There is a high rip current risk today
Short Term - Wednesday
High pressure builds across Quebec with a drier airmass building in. Pwats fall to an inch or less. There is hint of a weak backdoor frontal passage, which could spark an isolated shower. The forecast was left dry for now as the convergent region of the jet arrives. However, if the modeling becomes more consistent a few showers or sprinkles may need to be added. The NBM was used for temps.
There is a moderate rip current risk for Wed
Long Term - Wednesday Night Through Monday
The core of a deep layered ridge builds to our southwest then south Wednesday night through Thursday night, with its axis sliding offshore on Friday.
Subsidence under the ridge should keep things dry Wednesday night- Thursday night and relatively cloud free Wednesday night and Thursday. Week low level warm advection should bring some cloud cover on Thursday night.
Lows Wednesday night should be a few degrees above normal. Highs on Thursday should be a few degrees below normal and lows Thursday night around 5 degrees above normal.
A 700 hPa shortwave working its way up the back side of the ridge on Friday warrants slight chance probability of precipitation for showers/thunderstorms to the northern Tier of the Lower Hudson Valley/W Passaic County/far N Fairfield County, with dry conditions expected elsewhere. Highs on Friday should be around 5 degrees above normal.
A northern stream trough passes to the north Friday night, with mainly zonal flow over the region, the bulk of the energy associated with this trough will stay north of the area. As a result only have slight chance probability of precipitation Friday night.
The region remains under zonal-wsw flow aloft Saturday-Monday. The ECMWF is along in suggesting shortwaves embedded in the flow could bring some showers on Sunday and possibly Sunday night. So have slight chance probability of precipitation Sunday/Sunday night and have gone the remainder of the time frame from Saturday-Monday.
Temperatures should be above normal Friday night, then near normal Saturday, with below normal temperatures forecast Sunday and Monday.
Minor changes were made with this update to reflect the latest trends in observations and guidance. Main change was to accelerate the end time of any precipitation.
Winds and seas build to Small Craft Advisory (SCA) levels on the coastal ocean waters today, and just below on the remaining waters. A few 25 kt gusts cannot be ruled out especially on the S Shore Bays. The Small Craft Advisory on the coastal ocean waters was extended through tonight as seas stay in the 3-5 ft range, and may need to be extended through Wednesday as the NE flow builds seas once again. Winds below Small Craft Advisory levels elsewhere.
The waters around Long Island should experience a light to moderate pressure gradient from Wednesday night-Saturday night, with winds around 15 kt or less. Gusts to around 20 kt are possible on the coastal ocean waters Wednesday night. Seas on the coastal ocean waters could be around 5 ft, especially over the southern 1/2 of each zone Wednesday night and Thursday. Otherwise, sub-Small Craft Advisory conditions are expected from Wednesday night through Saturday night
Up to 1-2 inches of rainfall can be expected with the shower and thunderstorm activity through this afternoon. Some locally lower and higher amounts are possible.
Rainfall rates of one inch per hour or greater can be expected at times, especially this afternoon as the main frontal system comes through. Some minor flooding can be expected, with a chance for flash flooding, highest chances across western sections of the region where flash flood watch is in effect and lower chances to the east.
No significant hydrologic impacts are expected from later tonight through Monday
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time
NOAA New York NY Office: Watches - Warnings - Advisories
CT...Flash Flood Watch until 7pm EDT this evening for CTZ005-006- 009-010. NY...Flash Flood Watch until 7pm EDT this evening for NYZ067>075- 176>179. High Rip Current Risk until 8pm EDT this evening for NYZ075- 080-081-178-179. NJ...Flash Flood Watch until 7pm EDT this evening for NJZ002-004- 006-103>108.
Small Craft Advisory until 6am EDT Wednesday for ANZ350-353- 355.