textproduct: New York

SYNOPSIS

High pressure moves offshore through today. A cold front passes early tonight. A brief building of high pressure late tonight into early Thursday will be followed by high pressure moving offshore Thursday afternoon into Thursday evening. A strong cold front approaches from the west late Thursday night and moves across on Friday. High pressure from the south and west gradually builds in towards the start of the weekend before moving offshore Saturday night with a frontal system passing well north of the region for Sunday. High pressure builds in from the Great Lakes early next week.

NEAR TERM /THROUGH TONIGHT/

Key Points

* Dry conditions through tonight.

* Airmass further moderates today. Expect more substantial melting of the current snow cover today as temperatures climb well above freezing. Forecast highs today will be well within the 40s.

Upper level and mid level quasi-zonal flow will allow for quick steering flow. High pressure moves farther offshore while a cold front approaches from the north and west. This front passes through well north of the region early tonight, along with its main area of vertical forcing, allowing for a continuation of dry conditions across the local area.

At the surface, high pressure will continue to move farther out into the Atlantic. More southwest flow will allow for warmer temperatures as vertical mixing will be deeper. For today, max temperatures forecast are well into the 40s across much of the region.

High pressure builds in late tonight from the south and west. The pressure gradient will weaken and subsidence will keep mostly clear sky conditions across much of the area late tonight. Along with diminishing winds, optimal radiational cooling conditions will be setting up. Used MAV/MET blend to convey a more vast range of low temperatures, illustrating the variance of radiative cooling across the local region between urban heat island and rural outlying locations.

SHORT TERM /THURSDAY THROUGH SATURDAY/

Key Messages

* Dry conditions continue Thursday.

* Relatively mild airmass in place Thursday through early Friday morning.

* Strong cold front approaches late Thursday night and moves across early Friday. There is potential for strong wind gusts, especially along the coastline. Gusts could reach near 45 to 50 mph, with a low chance of exceeding 55 mph in some spots.

* A brief period of heavy rain is also probable with potential squall line of showers moving across early Friday along with a possible embedded thunderstorm.

* Strong cold air advection could result in some mix of snow and rain for some shower activity behind the cold front across parts of the interior Friday afternoon. Expect colder temperatures to return to the area Friday night into Saturday.

High pressure quickly moves offshore on Thursday with winds picking up out of the south to southwest. A strong frontal system will be moving towards the area Thursday. The parent low will be moving north of the Great Lakes. The associated warm front moves across late Thursday morning into Thursday afternoon while the associated cold front approaches Thursday night. The surface cold front will be strong and will be moving across early Friday.

Mild temperatures expected Thursday through early Friday morning following by decreasing temperatures for the rest of the day Friday. Temperatures will thus exhibit a non-diurnal trend. For this timeframe, there is a high likelihood of rain, potentially briefly heavy at times. Precipitation tapers off during Friday afternoon from west to east. With strong cold air advection, some snow may mix in with the rain, mainly across parts of the interior before all precipitation concludes.

With the strong cold front, a very steep pressure gradient sets up between lower pressure to the north and west and high pressure well offshore. Strong southerly flow will be initially limited due to inversions in the low levels but could mix down more with downward momentum transport with heavier rain. Relatively stronger winds become more widespread Friday with cold air advection increasing. Gusts up to 40 to 50 mph are looking more probable especially along the immediate coast with the potential for some gusts exceeding 55 mph. Strongest winds appear to be just ahead, along and behind the strong cold front overnight Thursday night through Friday morning.

The potential is increasing for advisory level wind gusts across much of the area Friday. LREF 00Z initialization shows mean wind gust of 40 to 45 mph across Southern CT and Long Island and taking the 75th percentile the wind gusts increase to the 45 to 50 mph across much of the forecast region for the forecast time of 7AM EST or 12 UTC Friday.

For the wind gust forecast Thursday night into Friday, an even blend of NBM and NBM 90th percentile was used for Thursday night but for overnight into Friday a greater weight of the NBM 90th percentile was used (specifically 2/3 NBM90th percentile compared to 1/3 NBM).

Elevated instability is indicated mainly along the coast for early Friday so there could be an embedded thunderstorm. Coverage for this is low so just isolated coverage and a slight chance possibility. Models indicate near zero Showalter Indices early Friday with mean MUCAPE in the LREF shown to increase to near 70 J/kg early Friday.

Surface high pressure builds in gradually Friday afternoon into the start of the weekend. Dry conditions return along with colder temperatures. Lows forecast Friday night will be much colder compared to the previous night. Highs forecast on Saturday will also be much colder than the previous day.

Any leftover snowmelt Friday and moisture laden grounds may have some patches that become frozen Friday night with temperatures falling below freezing. A mitigating factor to this would be if the winds keep staying up to dry out the surfaces before they freeze.

LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/

Key Point:

* Seasonable temperatures and mainly dry through the period.

A little warmer on Sun ahead of the next frontal sys, then colder on Mon with highs likely remaining in the 30s behind the next cold front. A dry fropa is modeled attm with limited moisture.

Temps close to normal again on Tue with the next weak sys potentially producing some light pcpn.

OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY

Thursday: VFR, possibly becoming MVFR or lower late in the day. S winds G15-20 kt late day.

Thursday night: IFR with rain. S winds G20-25 kt in the evening, increasing to 25-40 kt after midnight. LLWS after midnight.

Friday: Rain in the morning with MVFR/IFR, then rain ending with VFR. S to SW winds G35-45 kt in the morning, shifting W G25-35 kt in the afternoon. LLWS early.

Saturday: VFR.

Sunday: VFR. W winds G20-25 kt.

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

MARINE

Hazards are as follows:

SCA in effect for all ocean zones until 11PM this evening. To east of Fire Island Inlet, the SCA for those ocean zones go until 3AM Thursday. For non-ocean waters, SCA goes into effect at 7AM this morning and goes until 8PM this evening.

In addition, a gale watch has been issued for all waters for Thursday night through Friday evening, 6PM Thursday until midnight Friday night.

SCA conditions develop on all waters today into tonight, lasting longest across the eastern ocean zones where seas will be slower to subside below SCA thresholds. A brief time window of below SCA conditions is forecast late tonight through Thursday before winds and seas ramp up quickly Thursday night. The seas and wind gusts are the highest for Friday into Friday evening before going on a more decreasing trend late Friday night into Saturday.

Strong frontal system with strong cold front approaches late Thursday night and moves across early Friday. Gale force winds forecast across all waters mainly in a window from late Thursday night through Friday evening. Some parts of the waters early Friday could get to low end storm criteria (48-50 kt) but much of the time is expected to be near or within gale range.

A SCA will likely be needed on the non ocean waters Sat night as well as strong westerly winds continue behind a cold front. SCA conditions likely remain on the ocean waters into Mon. A period of gale gusts are possible on the ocean Sat night.

HYDROLOGY

Brief heavy rain will be possible late Thursday night into early Friday with showers moving across as well as any embedded thunderstorms. These will be quick moving and as such, are not expected to result in significant accumulations of rainfall. Around 1 inch to 1.25 inches of rain is forecast Thursday night through Friday but there could be some localized higher amounts. Outside of minor flooding in low-lying and poor drainage areas in localized areas where multiple rounds of heavy downpours are received, no other hydrologic impacts are expected.

TIDES/COASTAL FLOODING

Astronomical tides will be increasing with a new moon occurring Friday evening. The high astronomical tides along with an increasing southerly flow ahead of a deep low pressure system Thursday night into Friday may lead to minor coastal flooding along the south shore back bays during the Friday morning high tide cycle. There is still some uncertainty with the timing of the low and an associated cold front passing through the region.

With a slower timing tidal piling will be increased and there will be the potential for more widespread minor coastal flooding, with the possibility of localized moderate coastal flooding along the south shore back bays. At this time coastal flooding is not expected along the shores of the Long Island Sound. The Friday morning high tide cycle is the only one that will be potentially impacted at this time as the Friday evening high tide cycle is lower, and winds will likely be westerly at that time.

OKX WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 8 PM EST this evening for ANZ331- 332-335-338-340-345. Gale Watch from Thursday evening through Friday evening for ANZ331-332-335-338-340-345-350-353-355. Small Craft Advisory until 3 AM EST Thursday for ANZ350-353. Small Craft Advisory until 11 PM EST this evening for ANZ355.