textproduct: New York

SYNOPSIS

High pressure builds in from the west and then passes well to the south overnight. A cold front passes through the region Christmas afternoon. High pressure briefly returns Thursday night into Friday. A winter storm likely affects the area late Friday into Saturday morning. Another frontal system may affect the area Sunday into Sunday night. High pressure returns early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/

Key Messages:

* Dry, with near seasonable temperatures, becoming breezy Thursday afternoon.

High pressure builds in from the west, and over the region this evening. The high then drifts to the south tonight as a cold front approaches from the north. Tonight and Christmas Day will be dry, with high temperatures just a few degrees above seasonal normals. A cold front passes through the region Christmas afternoon with some cloudiness and breezy northerly winds.

SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/

What's Changed: There have been no changes to existing winter weather headlines. Snowfall amounts have been lowered slightly across coastal Long Island and NYC, and raised slightly across southern/coastal CT.

Key Messages:

* Confidence in a winter storm impacting the area Friday evening through Saturday morning continues to increase. Travel will be impacted Friday evening into early Saturday morning.

* Heavy snow is possible Friday night/early Saturday morning. Total accumulation ranges from 4 to 8 inches in the watch area and 2 to 5 inches east of the watch in SE CT and east end of Long Island.

Global models and their associated ensemble systems continue to highlight a quick moving shortwave rounding a strong upper ridge centered over the central plains, approaching the local area from the northwest Friday afternoon. At the surface, a cold high pressure centered over Quebec heads to the east as a surface low traverses the OH Valley, through PA and generally south of the local forecast area by 12Z Saturday. This will allow for a cold and dry arctic airmass to remain in place at the start as the shortwave and sfc low pressure approach Friday afternoon.

Model consensus continues to have the local area on the north side of the system, though it's notable that the 00Z NAM made a dramatic shift to the north with the sfc low. As is typical with the NAM in warm nose aloft scenarios, this run is either an anomaly, or the beginning of the trend that will need to be watched over the next several model cycles, as this track would lower snow totals across NE NJ and the LoHud at the expense of sleet/IP. Nonetheless, thermal profiles from most 00Z guidance and the NBM continues to be suggestive of a period of decent snow growth from late Friday into early Saturday across much of the CWA. Best h7 frontogenetic forcing appears on a line from SWF-LGA-HVW by 00-03Z Saturday, though this feature continues to wiggle with the sfc low track changes from guidance to guidance. Areas that fall under any heavy banding will pick up the highest snowfall totals with the highest rates, with the typical positional uncertainty this far out on exactly where that will happen.

All said, and in conjunction with the latest WPC WSO and neighboring WFOs, held the line on existing winter storm watch areas with this update. Should the trend of a more northerly low track solution continue, warning level snow could be possible for SE CT and the watch would need to be expanded there.

Snowfall Forecast: 4 to 8 inches possible within the watch area and 2 to 5 inches further east outside of the watch. A reasonable worst case scenario of 8 to 10 inches currents exists within the watch area with potential locations further east could still see warning criteria met.

Snowfall rates: Peak rates around 1 inch per hour possible. There is a low chance rates could come close to 2 inches per hour in heavier banding. The snow may initially begin with a higher ratio (drier snow) and then trend to a lower ratio (wetter) as the storm moves across the area. This will be fine tuned over the next day or so as high range guidance comes into range and the event draws closer.

As noted above with the trend in the 00Z NAM, there is still some concern with the warm advection aloft Friday night bringing in a mix with sleet late in the event. The latest (01Z) NBM probability of sleet is very low and trends seem to be leaning towards keeping the precipitation all snow across the area. Models can sometimes underestimate the warm advection aloft. This is something that will need to be watched, especially for parts of northeast NJ and interior Lower Hudson Valley as this is the direction the warm air aloft tries to move in from the west.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Key Messages:

*The next system for Sunday afternoon into early Monday looks to be mainly rain with only a chance of a wintry mix across the interior. Highest probabilities for precip occur late Sunday and persist through Sunday night into early Monday.

*Dry weather returns on Monday behind the frontal system into midweek with below normal temperatures expected.

OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY

Late Tonight: VFR. NW/N gusts subsiding to 20 kt and becoming occasional.

Friday: VFR in the morning, becoming IFR in snow from KBDR and KISP and west mid to late afternoon. LIFR, possibly VLIFR in snow Fri Eve/night across the region. Low potential (<30%) for IP/RA to mix in Fri Night for NYC/NJ metro and LI terminals.

Saturday: IFR with AM snow, low potential (<30%) for IP/RA to mix in Sat AM for NYC/NJ metro and LI terminals. IFR conditions may linger through the afternoon with a mix of light snow/DZ/FZDZ. Improving conditions late Sat into Sat eve.

Sunday: MVFR/IFR with rain developing in the afternoon, continuing overnight.

Monday: MVFR/IFR with rain AM, improving in the afternoon. SW/W winds G25-30 kt.

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

MARINE

With increasing winds ahead of a cold front SCA conditions develop on the ocean waters early this morning, and then with the passage of the front later today, northerly gusts continue at SCA levels through tonight. SCA on all waters through early Friday address this.

Low pressure then passes south of the waters Friday night through Saturday. Conditions will remain below SCA levels Friday into Friday night. Winds and seas build behind the system later Saturday with the next potential of SCA conditions. Seas should briefly subside Sunday. Another frontal system impacts the waters Sunday night. This will bring another threat of SCA conditions. Behind the system on Monday, gales are possible and this is mentioned in the HWO.

HYDROLOGY

No hydrologic impacts are expected into early next week.

OKX WATCHES/WARNINGS/ADVISORIES

CT...Winter Storm Watch from Friday afternoon through Saturday afternoon for CTZ005-009. NY...Winter Storm Watch from Friday afternoon through Saturday afternoon for NYZ067>075-078-080-176>179. NJ...Winter Storm Watch from Friday afternoon through Saturday afternoon for NJZ002-004-006-103>108. MARINE...Small Craft Advisory from 7 AM this morning to 4 AM EST Friday for ANZ331-332-335-338-340-345. Small Craft Advisory from 7 AM this morning to 10 AM EST Friday for ANZ350-353-355.