AFDOKX

Area Forecast Discussion
National Weather Service New York NY
710 PM EST Sat Dec 21 2024

.SYNOPSIS...
High pressure builds into the region through Sunday night, beginning 
to push east offshore on Monday. A weak frontal system
approaches Monday night and moves through Tuesday. High 
pressure builds back into the area Wednesday and remains in 
control through Saturday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
** COLDEST AIRMASS OF THE SEASON BEGINS TONIGHT **

Until winds weaken later tonight, hazardous driving conditions could 
continue in spots due to blowing snow left on the ground, reducing 
visibilities. A Special Weather Statement is in effect until 10pm 
for this risk. 

Tonight, surface low pressure continues to exit over the Canadian 
Maritimes while surface high pressure gradually moves towards the 
region from ONtario and the Great Lakes. Simultaneously, deep trough 
of low pressure will remain over the area with continued cold air 
advection aloft as 850mb temperatures get down to -15C. 

Temperatures will drop to the teens tonight across the area with 
some interior areas dropping into the upper-single digits, while 
some areas of the NYC metro may only drop to near 20. Winds are 
forecasted to stay somewhat elevated into tonight with NW gusts 
dropping from 25-30 mph early this evening to 15-25 mph late tonight 
and early tomorrow morning. This is due to a continued pressure 
gradient between the departing low and the approaching high. This 
will keep temperatures from dropping much lower than forecast. 

However, should winds drop lower than the currently forecasted 
tonight, its possible radiational cooling may have a more pronounced 
effect on cooling things down further than forecasted. Especially 
since clear skies are expected tonight. 

Given the anticipated cold temperatures and the still present winds 
tonight, wind chills are forecasted to be between 7 to 0 across 
coastal areas of SW CT, LI, NYC, and NE NJ. Other interior areas, 
the LI PIne Barrens and SE CT could see wind chills drop between 0 
and -6.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
Surface high pressure begins to really take over on Sunday from the 
west and north as the upper-level trough axis pushes east of the 
area offshore. Sunny skies are expected with NW winds continuing to 
wind down. 

Frigid highs in the mid-to-low 20s are expected Sunday afternoon. 
This is around 20 degrees colder than the climatological average. 
Maximum afternoon wind chills will be in the mid/low-teens area-
wide.

Surface high pressure starts to center over the area Sunday night 
leading to light or calm winds under clear skies as an upper-level 
ridge begins to build in. This will keep arctic air in place. 
Optimal radiational cooling conditions are expected Sunday night. 
Therefore, Sunday night will see the coldest temperatures so far this 
year. 

Sunday night lows are forecasted to be in the mid/low-teens for 
parts of Long Island, NYC metro, and coastal areas of NE NJ and S 
CT. Northern interior areas in addition to the LI Pine Barrens will 
see the coldest lows in the single digits. Some of the furthest 
interior areas may only be a few degrees away from zero. 
Despite cold temperatures, wind chills will not be a significant
factor and will even be higher than the night previously due to
nearly calm winds. 

High pressure remains in control Monday, but begins to shift 
offshore in the afternoon, leading to southerly winds returning as a 
shortwave approaches from the west. This will also lead to 
increasing cloud cover in the afternoon and early evening west to 
east. Temperatures will be moderated due to rising heights aloft and 
the winds becoming southerly. As well as increasing 850mb 
temperatures. Highs on Monday are forecast to be in the mid-20s
to low-30s area-wide withe areas of the NYC metro and southern 
coasts of Long Island possibly getting back above freezing.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Zonal flow aloft to start out the long term. A short wave approaches 
from the Great Lakes region Monday night, while another approaches 
from just south of Hudson Bay, with the two phasing over the eastern 
Great Lakes to start off Tuesday morning. The associated cold front 
remains to the west Monday night, with a surface low moving east or 
east southeast during this time frame across the Great Lakes and 
also ending up over the eastern Great Lakes by daybreak Tuesday 
morning.

The system looks to remain positively tilted as it moves through our 
region Tuesday. The aforementioned surface low will weaken as it 
moves toward the area, and then a secondary low develops well 
offshore. With weak lift associated with the front and much of the 
dynamics remaining north of the region, not much in the way of 
precipitation is expected. Whatever does fall will likely be snow 
for much of the region, with perhaps a rain/snow mix for eastern 
Long Island and southeastern CT Monday night into Tuesday. However, 
if any snow accumulates, it may be just a dusting, with only a 
couple of tenths expected (a few hundredths of an inch of liquid 
equivalent expected).

Thereafter, high pressure remains in control, situated over northern 
New England and southeastern Canada through the end of next week. A 
frontal system to our west tries to make its way into our area 
Friday night into Saturday, but the 1034-1038 high over southeastern 
Canada may win out, and any precipitation may run into some dry air. 
This far out, there is of course a great deal of uncertainty, so 
stuck close to the NBM. 

Seasonable temperatures expected through Thursday. Temperatures 
start to rise a few degrees above normal on Friday and a few more 
degrees on Saturday with strong subsidence occurring over the
area.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
High pressure builds across the terminals through Sunday. 

VFR through the TAF period. 

NW winds 15-20 kt gusting 25-35 kt this evening. NW sustained 
winds weaken to 10-15 kt overnight with gusts settling to 20-25 kt. 
Gusts could briefly end at some outlying terminals early Sunday 
morning. NW winds continue on Sunday with gusts around 20 kt 
possible after day break, ending around 16-18z. 

 ...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...

Peak gusts around 35 kt through 00z. 

Gusts may become occasional late tonight into early Sunday morning. 

OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...

Sunday Night-Monday: VFR. 

Monday night-Tuesday: Chance of MVFR in light snow/light rain mix, 
mainly into Tuesday morning. 

Wednesday-Thursday: VFR. 

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

&&

.MARINE...
Light freezing spray is possible tonight, mainly across the Long
Island Sound where water temperatures are a bit lower.

Small Craft Advisories remain in effect for all waters this evening. 
As the high builds toward the waters tonight, winds and gusts will 
fall below advisory levels on the non ocean waters late tonight, and 
on the ocean waters early Sunday morning, with seas remaining 
elevated into early Sunday afternoon. 

Once the advisories end, winds and waves are expected to remain
below SCA criteria through Thursday of next week. However, 
waves may briefly touch 5 ft on the ocean waters Tuesday into 
Tuesday night with the passage of a cold front in association 
with strong cold advection behind the cold front.

&&

.HYDROLOGY...
No hydrologic impacts expected into the beginning of next
weekend.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 3 AM EST Sunday for ANZ331-332-335-
     338-340-345.
     Small Craft Advisory until 1 PM EST Sunday for ANZ350-353-355.

&&

$$

SYNOPSIS...JP/BR
NEAR TERM...BR/JT
SHORT TERM...BR
LONG TERM...JP
AVIATION...JMC/DS
MARINE...JP/BR
HYDROLOGY...JP/BR