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000 
FXUS61 KOKX 201348
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
848 AM EST Wed Nov 20 2019

.SYNOPSIS...
Deepening low pressure well east of the area today will pass
just east of the Canadian Maritimes tonight into Thursday, while
high pressure builds in from the west. The high moves offshore 
Thursday night. A cold front then crosses the area on Friday, 
followed briefly by high pressure Saturday. Low pressure may 
impact the region Saturday night into Sunday, before high 
pressure returns early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Have removed any mention of snow mixing in this morning across 
interior southern CT based on warmer boundary layer temperatures
and the light nature of the precipitation. Have also added 
sprinkles across the western half of the area this morning with 
the upper low moving across.

Upper trough and closed low across area this morning will lift
north and east today, while offshore low pressure continues to
deepen. Ridging over the mid section of the country and 
associated surface high pressure will also build east today. 
This will result in a gradually strengthening northerly flow
between the departing low and building high. Gusts to around 20
mph will be possible by afternoon, strongest along the coast.

There will also be plenty of clouds associated with the upper
trough and wrap around moisture as it passes to the east. HiRes
models continue to show weak reflectivity returns developing 
across eastern sections of the area this morning into the 
afternoon with sprinkles and/or light rain, mainly across 
eastern LI and southeast CT. Any rainfall will be light and 
likely brief. 

Some clearing develops late this afternoon across western 
sections of the forecast area.

Daytime highs will be held in check by the cloud cover and
northerly flow with readings not getting out of the 40s. This is
about 5 to 8 degrees below normal.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Ridging both aloft and at the surface builds into the area
tonight through Thursday. This will result in clearing skies
and a brisk northerly flow that diminishes late tonight into 
Thursday.

Lows tonight will be around 30 well inland, to the lower and 
mid 30s along the coast. Highs on Thursday will be in the mid 
40s to around 50. These values are a shade below normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A fairly progressive flow pattern continues to be shown by the 
models for the long term. The main system of concern may occur 
Saturday night into Sunday with models and ensembles continuing 
to indicate large differences in track which will have 
significant implications on low pressure intensity, temperature 
profiles, and precipitation amounts. 

Before the weekend system, ridging both at the surface and aloft 
Thursday night will give way to an amplifying northern stream 
shortwave on Friday. A cold front will move across on Friday as the 
shortwave swings through New England. The warmest temperatures of 
the long term period will occur ahead of the front as readings rise 
into the lower and middle 50s inland and upper 50s near the coast. 
The overall trend in the models has been for less moisture as the 
front moves across and have lowered PoPs to follow this idea. It is 
entirely possible that the front moves across the region dry. A 
consensus of the models has the front moving offshore late afternoon 
and early evening. Winds will increase Friday night behind the front 
with NW wind gusts 25 to 30 mph. 

Progressive ridging moves overhead on Saturday as a split flow 
pattern develops across the central States. The southern stream 
system of concern is currently located along the southwest coast. 
This system will slowly move towards the Central States through 
Saturday. The northern stream shortwave energy of concern, currently 
located over the North Pacific, should near the northern Plains on 
Saturday. What happens thereafter is likely to be one key piece to 
the track and intensity of the low pressure Saturday night into 
Sunday. The ECMWF and GFS differ in where the northern stream energy 
moves, with the GFS diving south around the base of the mean upper 
trough. The ECMWF has the energy beginning to interact with the 
southern stream wave Sunday morning across the Great Lakes. Both 
models have the low pressure of concern tracking over or near the 
Long Island coast Saturday night into Sunday despite the differences 
in the northern and southern stream interactions, which may lend 
some credibility to further north solution. The CMC evolution is 
much different with the southern stream system interacting with a 
northern stream wave moving across southeast Canada, but the low 
pressure is weaker and much more progressive. The spread in the 
ensembles is large with several members in the more inland camp with 
several further offshore. While there is some agreement with the 
surface pattern on the GFS and ECMWF, run-to-run continuity is low. 

Did not make large changes to the previous forecast due to the 
aforementioned uncertainties. Saturday will largely be dry with 
precipitation chances increasing quickly from south to north 
Saturday night. Have increased PoPs slightly across the southern 
half of the area late Saturday night into Sunday morning. 

A track closer to the coast like the GFS and ECMWF indicate would 
largely be plain rain across the entire region. A track like the 12z 
Tuesday runs of the GFS and ECMWF, which was further off the coast 
of Long Island Sunday morning, could introduce some PTYPE issues 
inland, but also concern of how far north the precip reaches. 
Temperature profiles are also marginal even with a further offshore 
track. The system is progressive which should help to limit the 
duration of any impacts with the low. 

The system quickly lifts north and east towards the Canadian 
Maritimes late Sunday into Sunday night. High pressure returns early 
next week. Temperatures should be below normal this weekend and then 
approach normal early next week.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
Overhead moisture slowly shifts east today as a high pressure 
system builds to the west. This will allow MVFR ceilings, mainly
east of the NYC terminals, this morning to slowly improve 
throughout the day. Though uncertainty exists with the exact 
timing, expect VFR conditions to dominate the metro TAF sites 
late this afternoon and then throughout the area this evening. 
Prior to this some light intermittent drizzle will be possible 
for eastern most TAFs sites in SE CT and eastern Long Island. 

Winds today will remain out of the NW, to the right of 310
magnetic, and increase to 10-15kt with some gusts to around 
20kt possible.


   ...NY Metro Enhanced Aviation Weather Support...

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

KJFK TAF Comments: Periods of MVFR conditions possible through
16Z.

The afternoon KJFK haze potential forecast is GREEN...which implies 
slant range visibility 7SM or greater outside of cloud.

KLGA TAF Comments: Periods of MVFR conditions possible through
16Z.
 
The afternoon KLGA haze potential forecast is GREEN...which implies 
slant range visibility 7SM or greater outside of cloud.

KEWR TAF Comments: Occasional gusts are possible before 17Z.

The afternoon KEWR haze potential forecast is GREEN...which 
implies slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected. 

KISP TAF Comments: Intermittent light drizzle may be possible 
during the day. MVFR conditions may persist passed 16Z.


.OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
.Thursday...VFR.
.Friday...Chance MVFR in rain showers. SW gusts 20-25 kt in PM.
.Saturday...Chance MVFR/IFR in PM rain.
.Sunday...Chance MVFR/IFR in rain in the morning.

&&

.MARINE...
Marginal SCA conditions develop on the ocean waters this
afternoon as northwest winds increase between deepening low
pressure offshore and high pressure building in from the west.
Winds and seas begin to diminish late tonight as high pressure
approaches. SCA seas on the ocean waters could linger into 
Thursday morning, especially east of Moriches Inlet.

Winds and seas increase to SCA levels ahead of a cold front on 
Friday. The cold front passes east Friday afternoon with SCA 
wind gusts on all waters continuing Friday night. There could be
a few gale gusts on the waters east of Moriches inlet, but this
does not appear to be of long duration. Ocean seas will slowly 
subside behind the front.

Conditions will briefly fall below SCA levels on Saturday and 
Saturday night. SCA conditions are possible on Sunday as low 
pressure may impact the waters. The track of the low will 
ultimately determine how high seas build and the intensity and 
duration of stronger winds.

&&

.HYDROLOGY...
No hydrologic impacts are anticipated through Saturday. 

1/2 to 1 1/2 inches of liquid equivalent precip is possible
Saturday Night into Sunday with low pressure potentially 
impacting the region.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) is operating 
at reduced power until further notice.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 7 AM EST Thursday for ANZ350-353-
     355.

&&

$$
SYNOPSIS...DS/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...DS

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