Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 261754
Area Forecast Discussion
National Weather Service New York NY
1254 PM EST Sun Feb 26 2017
High pressure builds along the Eastern Seaboard today. The
strengthening high drifts over the Atlantic on Monday. A warm
front sets up in the vicinity on Tuesday, followed by a cold
frontal passage Thursday. A clipper low may impact the area by
the end of the week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast on track...Only changes at this time was some lowering
of cloud coverage for today as downslope is effectively dissipating
the stratocumulus - only the Hudson Valley is mostly cloudy.
Low pressure was over the Canadian Maritimes this morning, with
the associated cold front extending southward over the
Atlantic. Some snow showers and flurries were noted across
Upstate New York, but downsloping flow and subsidence are
expected to keep the forecast area dry today. A few flurries
cannot be ruled out of a potential broken deck around 4500 feet.
WNW winds this morning should gust to 20-35mph, strongest near
the coast and over NYC. Wind gusts should diminish this
afternoon, as 950-850 winds diminish to around 25 kt by evening.
The guidance was in good agreement so a blend was used for
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
After the diurnal cumulus dissipates this evening, model time
heights suggest the mid and high clouds will hold off for all
if not most of the night. With winds decoupling, especially in
the usual outlying spots, temperatures were nudged slightly
.LONG TERM /MONDAY THROUGH SATURDAY/...
The forecast was generally on track for the extended. The most
significant change was to include a chance for snow on Friday.
An increase in mid level moisture will produce overcast skies
by the end of Monday. A lack of deep moisture and lift are
limiting factors for the development of precipitation at this
time. The forecast has therefore been kept dry through Monday
night. Rain chances increase Tuesday and Wednesday as Gulf
moisture infiltrates the region. Gusty winds of 35-45 mph are
likely Thursday with strong low level cold advection behind the
cold front and winds from 950-850 hPa progged at 40-50kt. There
is some potential for wind advisory criteria to met both in
coastal areas and at higher elevations. After the main band of
rain with the front, there could be some residual scattered
showers with steepening lapse rates and strong vorticity
advection. With the cold air pouring in, these showers could
mix with or change to snow. The passage of an Alberta Clipper
then appears to be a little more likely on Friday per the 00Z
model suite. As a result, a chance of snow has been introduced
to the forecast. Cold on Saturday with wind chills potentially
in the teens for most of the day.
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --High pressure moves east and offshore Monday. VFR conditions are
SCT-BKN Stratocumulus of 4-5 KFT is mainly confined to the
Lower Hudson Valley this afternoon. WNW flow (mainly 280-300
degrees direction) will gust to 20-25 kt until early evening
with some gusts near 20kt for early to mid evening. Clouds and
winds diminish late tonight. Return SW flow develops Monday,
becoming gusty once again late morning into the afternoon with
gusts near 20 kt.
.OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
.Monday-Monday evening...VFR. SW winds G15-20KT Monday
afternoon, subsiding at night.
.Late Monday night-Wednesday...Chance of MVFR or lower. LLWS
.Wednesday night...IFR or lower possible. SW winds G15-25KT
possible along coast.
.Thursday...MVFR possible. W-WNW winds G30-40KT probable.
.Friday...MVFR/IFR possible with a chance of light snow. W
-- End Changed Discussion --
Wind gusts over the waters diminishing in the afternoon as low
level winds diminish to around 25 kt. Winds continue to diminish
tonight from W to E. Thus, SCA through midnight over the
western waters and until 6am Monday on the eastern waters.
There is some question on Monday as to whether or not we mix down
any of the 25-30KT low level winds, maybe by late afternoon - with
the best chance closer to the coast. Given confidence in occurrence
of SCA of less than 80 percent, did not extend SCAs over the eastern
waters into Monday.
Low level mixing should be limited Monday night and Tuesday, so even
though low level winds are 25-35 kt, have gone with a sub-small
The pressure gradient tightens Tuesday night, allowing for at least
seas to possibly build to SCA levels east of Moriches Inlet.
The pressure gradient continues to tighten on Wednesday, with SCA
conditions likely on the coastal ocean waters, and possible on the
non-ocean waters. These conditions should continue through Wednesday
With strong cold advection forecast for Thursday and low level winds
of 40-50kt progged in some guidance, gales are likely on the coastal
ocean waters and possible on the non-ocean waters. There is a small
chance for gusts to storm force as well on the coastal ocean waters.
These threats will be highlighted in the HWO.
The next chance for widespread precipitation is the middle of
next week, where around and inch of rain is possible.
MARINE...Small Craft Advisory until midnight EST tonight for ANZ335-338-
Small Craft Advisory until 6 AM EST Monday for ANZ330-340-350-