textproduct: New York

SYNOPSIS

Weak high pressure today gives way to a cold front passing through tonight. As it does, low pressure strengthens along the front to our south and east. High pressure then builds back Sunday afternoon and remains in control through Wednesday, when a warm front lifts to the north. A frontal system approaches into Thursday with a cold front pushing through Thursday night. High pressure then builds into Friday.

NEAR TERM /UNTIL 6 PM THIS EVENING/

High pressure weakens over the region today as its center shifts farther offshore. Clouds lower and thicken and cannot rule out a late day rain shower for southern portions of the forecast area, which could be mixed with snow north and west of the city. High temperatures closer to normal, but still only in the upper 30s to lower 40s for most areas.

SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/

Key Points:

* 1 to 4 inches of snow are expected across the area tonight into Sunday morning, with up to 5 inches in eastern Long Island.

* Winter Weather Advisories have been expanded slightly west and north to include all coastal zones from 10pm tonight through 1pm Sunday.

* Windy and cold Sunday night into Monday morning with wind chills below zero in some areas.

A strong closed h5 low dives SE through the Great lakes tonight. Associated positively tilted trough helps send a cold front through the area tonight. An area of low pressure forms along the front to our south in response. Because of the positive tilt, the low will be progressive and not really strengthen more rapidly until it is well off to our east. The precip shield with this system is however still expected well north of the weak low center and into our area thanks to synoptic lift courtesy of the right-entrance region of a strong upper jet streak adding to shortwave lift and the cold front itself.

NBM and WPC liquid equivalent precip are in line with consensus of deterministic and ensemble model output. While there appears to be only modest omega in the dendritic snow growth zone, the zone is large due the magnitude of the cold aloft and is saturated. Upward motion is still there with the upper divergence and PVA. This, along with much of snowfall occurring at night and cold/low wet-bulb zeroes, should help offset the more typical lower liquid to snow ratios one would expect with surface temperatures close to freezing, which will be the case for the coastal areas for much of the event.

Generally speaking, precip type starts as rain or a rain/snow mix at the coast with mainly snow inland this evening before a changeover to snow everywhere by midnight. Greatest impacts will be from late evening through at least mid-morning Sunday when the snow will have an easier time sticking to untreated surfaces. Snow should be exiting east out of area by around noontime Sunday.

Snow amounts have not changed much from the previous forecasts, but with more confidence in the totals, Winter Weather Advisories for tonight into Sunday have expanded to include coastal CT, Southern Westchester County, and additional parts of NE NJ.

Winds then pick up Sunday night into Monday and will be gusty with strong cold advection and a tightening pressure gradient. Wind chills late at night into Monday morning dip to -5 to 10 above, but are short of Cold Weather Advisory criteria. Highs on Monday will be averaging only around 30 - well below normal. Winds then diminish Monday night with wind chills not as cold this time, but still in the single digits to teens.

LONG TERM /TUESDAY THROUGH FRIDAY/

Key Points:

* Temperature moderation begins Tuesday night with a warm up Wednesday through Thursday night.

* Chance of rain Thursday into Thursday night with no hydrologic impacts anticipated.

A quasi zonal flow across the Lower 48 takes shape during the period. There are some differences in the operational models with the potential for amplification of an upper trough over the Upper Midwest and Great Lakes region during the second half of the week. The latter seems to hinge on the interaction of multiple streams of energy moving in from the North Pacific along with energy rounding the polar vortex, which will be bottled up well to the north. Thus, looking at a warmup during the mid week after temperatures start off well below normal, but end up climbing a touch above normal with highs forecast to top out in the upper 40s to lower 50s by Thursday. Some cooler air arrives on Friday, but due to the aforementioned complexities, the magnitude of colder air remains somewhat uncertain and would likely have some pacific air involved. Thus at this time the colder air late in the week should not be as cold as previous colder air masses. The NBM (which was followed) returns the region back to normal on Friday following the passage of a frontal system with a consensus approach being most prudent.

The next realistic chance of precipitation will be Thursday into Thursday night in the form of rain due to warm advection ahead of the system. Behind the cold front drier air moves in during Friday.

OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY

Sunday: MVFR to IFR, possibly LIFR at times to the east, in snow, mainly in the morning. Snow tapers off from west to east during the morning, and possibly as late as the early afternoon for far eastern terminals as conditions improve to VFR. NW winds gust around 25kt in the afternoon and night with peak gusts around 30kt.

Monday: Mainly VFR. NW winds G20-25kt. Gusts lower at night.

Tuesday-Wednesday: VFR.

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

MARINE

After collaboration with the surrounding offices, have issued a Gale Watch for the ocean waters for Sunday night into a portion of Monday morning. Before this, SCA conds expected today, followed by sub- advisory conds tonight before rising back to advisory thresholds Sunday morning. Decided to simply headlines and stretch the SCA leading up to the Gale Watch to from today through Sunday afternoon. As for the non-ocean waters, SCA in effect from late Sunday morning through Monday afternoon. Can't rule out occasional gale force gusts during Sunday night, but not enough coverage and confidence to go with a watch for these zones. Sub-SCA conditions are then forecast for all waters Tuesday as high pressure builds in from the west.

HYDROLOGY

There are no hydrologic impacts expected through the entire forecast period.

OKX WATCHES/WARNINGS/ADVISORIES

CT...Winter Weather Advisory from 10 PM this evening to 1 PM EST Sunday for CTZ009>012. NY...Winter Weather Advisory from 10 PM this evening to 1 PM EST Sunday for NYZ071>075-078>081-176>179. NJ...Winter Weather Advisory from 10 PM this evening to 1 PM EST Sunday for NJZ004-006-104>108. MARINE...Small Craft Advisory from 10 AM Sunday to 6 PM EST Monday for ANZ331-332-335-338-340-345. Small Craft Advisory from 10 AM this morning to 6 PM EST Sunday for ANZ350-353-355. Gale Watch from Sunday evening through Monday morning for ANZ350-353-355.