FXUS61 KOKX 150158

Area Forecast Discussion
National Weather Service New York NY
858 PM EST Thu Nov 14 2019

A trough near the region moves offshore tonight. A cold front
will follow, approaching Friday and moving across Friday night.
High pressure builds in during Saturday and will settle just
north of the area on Sunday. An offshore storm will pass south,
then east of the area Sunday night into Monday. A second
offshore system is expected to develop offshore Tuesday night
and move away during Wednesday. High pressure will build by
Wednesday night and settle nearby on Thursday.


Just a few minor adjustments through the overnight with
temperatures, dew points, and winds to better match
observational trends.

With high pressure moving well northeast into the Atlantic, the
local region will be in between low pressure systems in the
Southeast U.S. and in Southeast Canada. The cold front
associated with the Southeast Canada system approaches the
region tonight.

A trough will be moving offshore tonight. The trough will
linger offshore and some models are indicating some moisture
convergence and precipitation developing along it overnight
into early Friday. This also coincides with mid to upper level
positive vorticity advection increasing with height during that
time period. The models have indicated this to be just offshore.
Expecting clouds to linger around the coastal areas with a slow
decrease for inland locations overnight.

Lows were a blend of MET/ECS, relatively warmer for coastal
areas and coolest across the interior in accordance with where
radiational cooling will be more efficient.


For Friday, the trough moves offshore early. This will be
followed by a cold front that will approach the region from the
north and west. The flow ahead of it will become more westerly
and there will be some low level warm air advection ahead of the
cold front. This westerly flow will mean less marine influence
and with efficient vertical adiabatic mixing expected to 850mb
with those 850mb temperatures increasing to 3 to 4 degrees C,
this will translate to warmer surface temperatures. These were
taken from MET/ECS blend and further modified slightly with
highs in the upper 40s to lower 50s, remarkably warmer than the
previous day.

Not much forcing seen with the front with overall more negative
vorticity advection. Decreasing clouds forecast during the day.

For Friday night, the cold front moves across the region and
will bring in a colder airmass. The cold air advection will be
seen with the winds becoming more northerly and gusty as well.
Low level northerly wind backs to a more westerly wind in the
mid levels. Clouds continue to be minimal with the local region
being in between two main shortwaves (one in the SE US and one
in the Canadian Maritimes). Slight ridging seen in the mid
level height fields towards early Saturday giving subsidence and
keeping mostly clear sky conditions.

For lows, it will be coldest across interior where winds will
be lighter, and relatively higher winds will keep boundary
layer warmer across the coastal areas. ECS used for mins which
mostly range from the low 20s to low 30s.


To begin the period strong Canadian high pressure will anchor itself
just north of the region. Global guidance suggest a rather strong
surface high in the neighborhood of 1036 to 1040 mb. A rather strong
confluence zone at 500 mb delivers the high slightly further south
with respect to the 12z model consensus than some previous runs.
This will have an impact on the wind speed forecast for the weekend.
Temperatures will average a good 15 degrees below average on
Saturday, and 10 to 15 degrees below average Saturday night. If
the high can build down just slightly further south than
anticipated then the stronger pressure gradient would be along
the southern portions of the area, or maybe even displaced just
to the south over the offshore coastal waters. Also the strong
confluence zone aloft to the north helps to displace a potent
southern branch feature just slightly further south to begin the
weekend. The exact placement of this feature will impact the
forecast for late in the weekend and into early Monday.
Basically the 12z global guidance keeps the southern branch
feature moving along enough and displaced far enough to the
south into Saturday night that the system has difficulty making
the turn due north into Sunday. There is actually very good
overall model agreement that the southern branch feature does
eventually turn north and perhaps just west of north by the
times it gets offshore a bit. This would mean by and large a
miss of any significant precipitation for our region, with
perhaps eastern New England capturing some of the western
periphery of the precipitation shield. Therefore mainly slight
chance POPs seems prudent for eastern sections later Sunday and
Sunday night, with chance POPs for far northeastern parts of our
region. Heights do rise rather quickly Saturday night and into
Sunday with the upper level low to our north lifting out quickly
as the pattern will be rather progressive due to a lack of
blocking. This will mean with temperatures well below average
for the first half of the weekend along with a biting north to
northeast wind temperatures will modify a bit into Sunday.
Although, with the northeast wind continuing throughout the
weekend the temperature moderation will perhaps not be as
noticeable. Another question is if precipitation from the
offshore low gets further northwest than expected would it be
cold enough in the low levels for a period of light freezing
rain late Sunday night and early Monday morning. Likely any bit
of cold air left behind would be quite shallow as it warms up,
especially above the boundary layer. If enough moisture gets
further west than anticipated there is an outside chance of a
bit of light frozen precip in the form of mainly freezing rain
for far NW CT and parts of the Hudson Valley. This will have to
be watched in subsequent forecast cycles.

The west coast ridge and east coast trough will attempt to re-
establish itself for early next week. As the first southern branch
system exits during the second half of Monday height falls get
renewed over the Upper Midwest as another shortwave rounds the base
of the newly formed longwave trough. Due to a lack of low level
moisture in the wake of the previous southern branch feature chose
to stay on the low side with POPs for the late Monday into early
Tuesday. By late Tuesday into Wednesday the atmosphere may get moist
enough once again as another shortwave is progged to round the base
of the trough. Global guidance suggests that by late Tuesday and
Tuesday night surface low pressure will form along and off the Mid
Atlantic coast. It is suggested that the overall wavelength of the
long wave pattern will shift just enough to the east to keep the
bulk of this system also mainly offshore. Also it appears that the
system will not deepen until enough upper level energy consolidates
offshore by early on Wednesday. By then the upper level trough axis
begins to pivot through the area and this system is more likely at
this time to have impacts to our north and east. The older ECMWF
runs were a bit slower than some of its global counterparts with the
evolution and overall speed of the upper level pattern. However, the
12Z ECMWF run was east and slightly faster, therefore confidence
with respect to the track is at least at a moderate level with the
mid week system.

High pressure off to the southwest will then build into the region
late Wednesday into Wednesday night providing brisk and dry weather.
The high will then settle just south of the area on Thursday
providing a dry day. Temperatures are expected to modify throughout
the period during the early portion of the week, then remain
seasonably cool late in the period for late Wednesday into


A trough of low pressure remains offshore through the night.
A cold front will follow, approaching Friday and moving across
Friday night.

VFR as skies gradually clear overnight.

W/SW winds will diminish as the night progresses. These winds
veer to the W. W winds under 10 kt expected on Friday morning,
then around 10 kt in the afternoon.

.Friday night...VFR. NW wind gusts 20-30 kt.
.Saturday-Sunday...VFR. Wind N-NE around 15kt with gusts 20-30kt.
.Monday...Sub VFR possible. Chance of rain near coast. NE wind
gusts 15-20 kt.
.Tuesday...Mainly VFR, with a chance of rain.


Gusty west/southwest winds tonight should remain below 25 kt.
These wind speeds diminish as the night progresses. Relatively
weak pressure gradient Friday will keep conditions below SCA
on the waters. Then, the pressure gradient will tighten Friday
night between low pressure off the Southeast Coast of the US and
high pressure to the northwest of the local region. Gale watch
starts on the ocean waters late Friday night and SCA conditions
will be likely on the non-ocean waters.

Gale wind gusts are expected on the ocean waters through the
day on Saturday and may linger through the weekend, especially
further east out on the ocean. Otherwise SCA wind gusts are
expected to continue on the non-ocean waters through the
weekend. Seas will build on Saturday as an easterly swell
develops and strengthens into the Saturday night. Seas will be
get as high as 10 to 11 feet in southern parts of the ocean
waters for late Saturday through Sunday. The winds and seas will
then gradually subside through Monday as low pressure exits the
coastal waters. Conditions will drop below SCA criteria for the
non-ocean waters by Monday afternoon, with SCA conditions
continuing out on the ocean through Monday and possibly Monday
night due to lingering elevated seas.


No hydrologic impacts are anticipated through the forecast


Due to the likelihood of an easterly swell developing during the
weekend and a persistent NE wind into early next week minor coastal
flooding for some coastal locations cannot be ruled out. The best
chance at waters levels approaching minor coastal flood thresholds
would be for the south shore western back bays and western sound
locations for mainly the late morning and late evening high tide
cycles on Sunday and potentially on Monday.


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


MARINE...Small Craft Advisory from midnight Friday night to 6 PM EST
     Saturday for ANZ330-335-338-340-345.
     Gale Watch from late Friday night through Saturday afternoon
     for ANZ350-353-355.



NWS OKX Office Area Forecast Discussion