Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
752 PM EDT Wed Oct 26 2016
high pressure across the region moves east late tonight as a warm
front approaches from the southwest. A frontal system moves
through the Great Lakes and northeast Thursday and Thursday
night. High pressure builds in on Friday and lasts into early
Saturday. A cold front moves through late Saturday, followed by a
weak low passage to our south on Sunday. High pressure then
returns early next week.
Near term /until 6 am Thursday morning/...
the center of high pressure will be passing well to the north,
across southern Canada, tonight as a warm front approaches from
the southwest. Winds are expected to decouple inland late this
evening and late tonight while along the coast some gradient is
expected to remain with a northerly flow veering to the east.
Also, high clouds were already overspreading the cwa, to be
followed by a mid deck late tonight. While there will be a period
of radiational cooling, conditions will not be ideal. As a result
went a little higher with overnight lows especially along the
coast. This conditions will preclude the formation of any frost.
Also, temperatures mostly above freezing along the coast. Will not
have any frost or freeze hazards tonight.
With weak warm advection set to begin after 06z and a warm front
approaching, light precipitation will be possible across the
western zones around 06z. Temperature profiles support a chance of
light snow inland and a mixture of snow and sleet, possibly rain
into northeastern New Jersey. The warm air above freezing looks to
move in too late for a chance of freezing rain.
Short term /6 am Thursday morning through Thursday night/...
as the warm front approaches Thursday morning a mixture of snow,
sleet and rain will be possible farther to the north and east. And
as the warm air aloft rises to above freezing surface temperatures
are also expected to rise to above freezing, so again will not
mention any freezing rain. If the warmer air at the surface is not
scoured out there will be a chance of a brief period of freezing
rain. This will be possible as the parent low remains well to the
west and north, and another low begins to develop along the triple
point around 15z. The warm front itself looks to move through the
coastal areas by Thursday afternoon and transition from stratiform
to convective precipitation.
Along the triple point and developing low lift will be increasing
and a moderate rainfall along the coast will be possible late in
the afternoon and into the evening. The coastal areas destabilize
Thursday evening with lifted indices falling and showalters zero
to minus two, so will have a mention of thunder along the coast.
The low is moving a little quicker than previous forecasts and
will be ending precipitation after 06z Friday.
Long term /Friday through Wednesday/...
trends in the latest model and ensemble data continue to indicate
that the strong shortwave and its associated low pressure system
will be east of the region Friday morning. The atmosphere dries out
quickly around day break, so will continue to go with a dry forecast
after 12z. Ridging builds aloft behind the shortwave and high
pressure takes hold at the surface. The gradient between the
departing low and building high will set up a breezy day with northwest
winds gusting 25 to 30 mph. High temperatures will be slightly below
normal in the middle and upper 50s.
The synoptic pattern will be progressive for the upcoming weekend
with middle and upper ridging moving east on Saturday and a northern
stream shortwave approaching from the northwest during Saturday. The
cold front associated with this shortwave looks to swing across
Saturday night. There are some differences among the latest guidance
with how much the shortwave will dig into New England. The overall
trend in the last several runs is for the shortwave and its energy
to pass to the north. The system also will have limited moisture to
work with, so have continued with slight chance pops. SW flow ahead
of the front will help increase temperatures into the lower 60s for
The front should settle to the south of the region late Saturday
night into Sunday. However, the 12z European model (ecmwf) stalls the boundary a
little closer to the region than the other models. There is a
general agreement among the models that another shortwave will also
pivot across the region on Sunday. The European model (ecmwf) is the furthest north
with a weak low developing on the frontal boundary, with the rest of
the deterministic models further south across the Carolinas. There
is an approaching 80 kt jet at 300 hpa late Sunday and the region
will lie near the left exit region. Do not want to remove the slight
chance pop at this time with the shortwave, and approaching upper
jet. In any case, moisture is limited so do not expect any
significant precipitation. High temperatures on Sunday will be near
The shortwave quickly departs to the east Sunday night with ridging
rebuilding aloft Monday into Tuesday. High pressure will also return
at the surface. Temperatures may fall a bit below normal on Monday
before returning to near normal levels on Tuesday. Uncertainty
increases late in the period as another cold front may approach
Wednesday. However, there is low confidence in the timing of this
system as the GFS may be breaking the ridge down too quickly. For
now have just followed a model consensus on Wednesday with
temperatures above normal and dry conditions.
Aviation /00z Thursday through Monday/...
high pressure moves across the area tonight and then gives way to
a low pressure system approaching from the Ohio Valley on
Thursday and crossing Thursday night.
Light north/northwest veer to the NE overnight and then east/southeast on Thursday.
East/southeast winds increase Thursday afternoon with gusts.
Mid and high level clouds will work in from the west tonight and
then lower toward morning with light rain developing around
daybreak. At kswf...precip could start as a period of wet snow
with little to no accumulation expected. There is a low chance of
any freezing rain and/or sleet.
MVFR conds likely develop from west to east during the late
monring into early afternoon with steadier light rain...dropping
to IFR in the late aft/eve in moderate rain. Timing of
deteriorating conds may be off by 1 to 2 hrs...depending on how
quickly the low- levels moisten.
New York 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: timing of deteriorating conditions may be off
by 1 to 2 hrs.
Klga taf comments: timing of deteriorating conditions may be off
by 1 to 2 hrs.
Kewr taf comments: timing of deteriorating conditions may be off
by 1 to 2 hrs.
Kteb taf comments: timing of deteriorating conditions may be off
by 1 to 2 hrs.
Khpn taf comments: timing of deteriorating conditions may be off
by 1 to 2 hrs.
Kisp taf comments: timing of deteriorating conditions may be off
by 1 to 2 hrs.
Outlook for 00z Friday through Sunday...
Thursday night...IFR or lower conds in rain in the
evening...improving to VFR in wake of cold frontal passage after
midnight. Southeast winds 10 to 20 kt with gusts to 25 kt Thu
eve...shifting to west in wake of cold frontal passage.
Friday...VFR with strong northwest flow behind a cold front.
Saturday...VFR with gusty southwest flow possible. Low chance of
showers Saturday afternoon/evening.
Sunday and Monday...VFR.
high pressure will be across the forecast waters tonight with a
frontal system approaching late tonight and moving through the
waters Thursday and Thursday night. Thursday afternoon gusts on
the ocean will be around small craft levels ahead of an
approaching cold front. Seas will be building as well and reach
small craft by Thursday evening. Thursday night there will be
occasional small craft gusts on the remainder of the waters as low
pressure moves through, and small craft conditions continue on the
Increasing pressure gradient between low pressure departing to
the east on Friday and building high pressure to the south will
present Small Craft Advisory conditions on all waters. The Small Craft Advisory will continue on the
ocean through Friday evening, and will go into effect on remaining
waters 10z Friday. There remains a possibility for gale force
gusts on the ocean, but confidence is low on the occurrence being
more than occasional. Will continue to highlight in the hwo, but
for just the ocean waters. Winds will weaken Friday night as the
high settles over the waters. Seas will also subside below Small Craft Advisory
High pressure shifts offshore Saturday with an increasing SW flow.
Gusts to 25 kt and seas building to around 5 ft will be possible in
the afternoon on the ocean waters. These winds will slowly diminish
Saturday night as the front moves through, but seas may take longer
For Sunday into Monday, high pressure builds over the waters with
sub-Small Craft Advisory conditions forecast.
precipitation develops late tonight and continues through
Thursday night. Liquid accumulations of 1/2 to 3/4 of an inch of
likely, with a trace to 1 1/2 inches of snow and sleet possible
across portions of the lower Hudson Valley into northeastern New
Jersey, and northern Fairfield County of Connecticut.
Widespread significant precipitation is not expected for the rest
of the forecast period.
Marine...Small Craft Advisory from 6 am to 6 PM EDT Friday for anz330-
Small Craft Advisory from 2 PM Thursday to 6 PM EDT Friday for