textproduct: New York

SYNOPSIS

A strong cold front passes through the area late morning into the afternoon. High pressure then briefly builds in for the start of the weekend. A weak warm front passes nearby late Saturday into Saturday night followed by a cold front Sunday morning. A secondary cold front then passes Sunday night. High pressure returns Monday. Another frontal system looks to impact the region Tuesday into Wednesday.

NEAR TERM /THROUGH TONIGHT/

The forecasted impacts for the frontal system today remain mainly on track, with only minor adjustments made through tonight.

Key Messages:

* A strong cold front will move through near noontime on today, bringing strong to locally damaging winds and moderate to heavy rain, along with isolated thunderstorms.

* Potential tying or record breaking temperatures early Friday fall back into the 20s Friday night, to below normal levels. Any leftover moisture may freeze if drying does not occur.

Rainfall has begun already in some locations and will continue to increase in coverage through the morning hours. Strong low level jet lift and moisture convergence, plus a potential convective element with elevated instability, could cause the rain to be heavy at times. The heaviest rainfall likely occurs an hour or two after sunrise with some impacts to the morning commute with the threat continuing until the cold front passes through late morning/early afternoon with a line of convectively-enhanced showers. Areas of minor/poor drainage flooding are anticipated. Flash flooding is not a concern at this point with the system pushing through fairly quickly and the liquid equivalent of any remaining snow pack is probably no more than a tenth of an inch. Still a chance of a shower in the afternoon behind the cold front, and maybe even some snow mixed in well NW of the city towards sundown.

Regarding winds, an 80-90kt low level jet at 925mb shifts through much of the coastal area during Friday morning. Forecast soundings however show a strong low level inversion which has kept winds from mixing down for much of the area so far this morning. It appears that winds are going to have a tough time mixing down to the surface for much of the day. It might take surface temps reaching 60 degrees to get mixing deep enough to bring down gusts strong enough for high wind warning consideration, and some spots may warm up close to this. Thinking is that about 50% of the 925mb jet winds could still mix down anyway, which translates to higher-end wind advisory gusts, but cannot completely rule out a gust or two that reaches warning criteria. Not enough confidence that the occurrence would be widespread enough to warrant a high wind warning, but will keep messaging the threat of isolated 60mph gusts in the advisory. No change to the end time of the advisory, but can't rule out 46mph+ gusts for a couple of hours after midnight.

High temperatures occur in the morning generally in the mid to upper 50s. This is close to record high temperatures for the day. See the climate sections below for these records. Temps then fall somewhat with the rainfall by midday, then fall more steadily in the afternoon with the start of cold air advection behind the front. A more rapid drop in the temperatures then happens this evening as the advection strengthens behind the front. Depending on how much winds can dry out surfaces before temps fall below freezing in the evening, there could be spots where freezing of standing water occurs.

Dry weather for Friday night with high pressure building in. Winds will gradually diminish overnight.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Key Messages:

* Mainly dry weather this weekend though winds remain gusty.

A high pressure ridge shifts through the region Saturday afternoon and keeps us dry through Saturday night. A warm front looks to push through late on Saturday. Any precip with weak warm advection at night should remain to our north. Saturday's high temperatures are expected to be just below normal.

Another cold front pushes in early on Sunday with a secondary cold front pushing through Sunday night. No precipitation is anticipated with these frontal passages, though winds will remain quite gusty from the W/NW with gusts upwards of 30 mph.

LONG TERM /MONDAY THROUGH THURSDAY/

Key Messages:

* Mainly dry conditions are expected through Monday. Precipitation returns to the forecast on Tuesday of next week.

* A frigid airmass moves in on Monday. Temperatures become more seasonable by midweek.

A frigid airmass moves in for Monday with high temperatures only in the low 30s.

High pressure on Monday shifts offshore overnight, allowing the winds to relax and shift out of the SW on the back side of the high. Meanwhile, mid-level energy passing well north of the area will allow for a surface frontal system to impact the area on Tuesday. Precipitation is expected to move in early Tuesday and may begin as snow depending on surface temperatures. Marginal surface temperatures during the day Tuesday may allow for a rain/snow mix over much of the area in the morning, eventually transitioning to mainly a light rain into the afternoon. A lot of the precipitation types will depend on the timing of the frontal system, with an earlier pass-through allowing for more snow than rain, but either way, QPF and precip intensity look to be light so any significant impacts are not expected.

The system pushes east as it intensifies on Wednesday, allowing for high pressure to once again build into the area. Another weak and progressive shortwave may pass nearby on Christmas Day, but guidance is much too variable to hone down any details at this time.

OUTLOOK FOR 06Z SATURDAY FRIDAY THROUGH TUESDAY

Late Friday Night: VFR with W-WNW gusts gradually subsiding.

Saturday: VFR. Decreasing WNW winds becoming SW late in the day.

Sunday: VFR. W winds gusting 20-30 kt.

Monday: VFR with diminishing NW flow.

Tuesday: MVFR or lower possible with chances for -SN/-RA/-RASN.

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

MARINE

Gale Warning remains in effect for all waters through tonight. Isolated gusts up to 50 kt are possible this morning. Once the warning expires, a SCA will likely be needed on the ocean waters through at least Saturday morning, then gusts here may approach 30 kt once again Saturday night. SCA to near gale conditions are likely on the oceans Saturday night into Sunday with widespread SCA likely on the non-ocean waters by Sunday. SCA conditions likely persist on all waters through Monday morning before gradually dissipating Monday afternoon and evening. SCA conditions return on waters midday day to afternoon on Tuesday.

HYDROLOGY

Brief heavy rain will be possible this morning with showers moving across, as well as with any embedded thunderstorms that may occur into the afternoon along and ahead of the cold front. These will be quick moving and as such, are not expected to result in significant accumulations of rainfall. Around 3/4 to 1 1/3 inches of rainfall, with locally higher amounts, are expected. While hourly rainfall rates will mainly be around 0.25 in/hr or lower, heavier showers and thunderstorms may produce rates closer to 0.50-0.75 in/hr.

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.

No hydrologic impacts are expected Saturday through Thursday.

TIDES/COASTAL FLOODING

A new moon occurring this evening will result in as little as 1 3/4 ft of surge causing minor coastal flooding and 2 1/2 ft causing moderate impacts. A high end gale south-southeast flow ahead of a strong frontal system will bring likelihood for widespread minor coastal flooding during the Friday morning high tide cycle for our Tri-State south facing coasts and even tidally affected rivers (Hackensack and Hudson R), with localized moderate along the southern bays of Queens and W LI.

Models are in good agreement with peak winds occurring during the time of high tide for much of the region, with frontal passage occurring after high tide this morning. This has increased the potential for widespread minor coastal flooding across vulnerable coastal locales along NY/NJ harbor, Jamaica Bay, great South Bay, twin forks of LI, and coastal Westchester/CT. Water levels will likely get close to moderate flood levels along Jamaica Bay and western Great South Bay, combined with rain and wave impacts, during morning commute, a coastal flood warning has been issued for exacerbated flood impacts. Otherwise, coastal flood advisories have been expanded into southern CT (wave action of 3-5 ft during high tide), E Bergen County and NE Suffolk County for similar reasoning as above/below.

With S/SE gales ramping up through the time of high tide (favorable direction for surge along south facing coasts), high wave action onto open water coasts, and potential coincidence of heavy rain, this forecast has been leaned towards the higher end of plausible scenarios. A blend between SNAP-EX 50th percentile (NYHOPS 95th percentile), ETSS and STOFS was used.

Offshore winds behind the cold front will end the coastal flood threat with subsequent high tides.

CLIMATE

Record High Temperatures:

December 19: KEWR: 60/1931 KBDR: 57/1967 KNYC: 58/1931 KLGA: 57/1957 KJFK: 56/1967 KISP: 55/2017

OKX WATCHES/WARNINGS/ADVISORIES

CT...Wind Advisory until midnight EST tonight for CTZ005>012. Coastal Flood Advisory from 8 AM this morning to 1 PM EST this afternoon for CTZ009>012. NY...Wind Advisory until midnight EST tonight for NYZ067>075- 078>081-176>179. Coastal Flood Advisory from 8 AM this morning to 1 PM EST this afternoon for NYZ071. Coastal Flood Advisory until 11 AM EST this morning for NYZ072- 074-075. Coastal Flood Advisory until 1 PM EST this afternoon for NYZ079-081. Coastal Flood Warning until 11 AM EST this morning for NYZ080- 178-179. NJ...Wind Advisory until midnight EST tonight for NJZ002-004-006- 103>108. Coastal Flood Advisory until 11 AM EST this morning for NJZ006- 104-106-108. MARINE...Gale Warning until 6 AM EST Saturday for ANZ331-332-335-338- 340-345-350-353-355.