Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 221758
Area Forecast Discussion
National Weather Service New York NY
158 PM EDT SUN MAY 22 2016
Low pressure will track east of Cape Cod today...then dissipate
near Nova Scotia on Monday. Another weak low will pass near the
region on Tuesday. High pressure will then briefly follow for
Wednesday and Thursday with a frontal system approaching from the
northwest late in the week.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --Minor changes made to the forecast. Clouds are diminishing over
eastern sections of the area, with stratocumulus developing as the
mid and upper level clouds depart and the sun allows for afternoon
heating. So, decreased cloudiness somewhat out east. Best chances
for showers continues to be north and west of New York City, with
dry conditions expected for the rest of the region for the
remainder of the afternoon.
Upr low over cntrl PA continues to inch towards the cwa this
mrng. Area of light rainfall from nern NJ thru the city into CT
will slowly slide ewd as a result. The low pres sys is way out
over the Atlantic...so the pcpn this mrng will be due to positive
vorticity advection increasing with height squeezing out residual
moisture in the region. This seems to be the reason there is a bit
more lgt rain and even dz being reported across the s fork of Long
Island into Block Island...where there is some deeper bl/llvl
The rain should become more showery in nature today with the upr
low over the ern seaboard. Best instability across the interior
and this lines up with the best mid lvl moisture...so highest
chances for rain in those areas. The ern portion of the cwa close
to the h7 low per the model progs so more mid lvl dry air.
Instability drops tngt aft sunset...so the models suggest pcpn
will rapidly dry out across the cwa. This consensus was followed
for the fcst...although any stronger activity embedded in the flow
could maintain overnight and produce a few surprise shwrs in the
The statistical models were in good agreement today...so used a blend
of the MET/MAV for temps.
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.SHORT TERM /MONDAY/...
Good model agreement that the main h5 low sets up near Hatteras
in the mrng...then drifts newd over the Atlantic during the day.
Mid lvl moisture is limited...but ely flow develops late which
should increase pws to over an inch per the GFS. The best chances
for rain may still though hold off in most areas til the eve
because of this initial lack of moisture. Warmer temps however
across the interior could offset the lack of moisture and provide
a net gain in instability...allowing for better rain chances
during the day. Pops highest west of the Hudson for that reason.
Temps close to guidance which again was in good agreement.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Global models continue to slow down with the progress of an upper
trough over the Eastern U.S. at the start of the week. A closed
low at the base of the trof over the Mid Atlantic states will
lift slowly north into Tue, and then northeast Tue night into Wed.
There are some discrepancies amongst the guidance with how quickly
this feature lifts out, with the operational GFS being the slowest
of the solutions. The interaction with a northern branch trof
moving across Hudson Bay appears to be the key, with the
magnitude of this feature varying. A model consensus approach
seems to be best here with the differences being rather small for
this juncture in time. Upper level ridging then expands across the
area for the second half of the week with very warm conditions to
ensue. In addition, the Sub tropical high over the western
Atlantic begins to expand west toward the East Coast at the close
of the period. This will allow for a more humid SW flow to develop
around the periphery of the high.
As for any rain, the best chance looks to be Mon eve into Tue with
the approach of the upper low. The GFS is the deepest, farthest
west, and slowest with the sfc low. Model consensus is for a
weaker and faster low, thus will keep rain chances at around 50
percent at this time. There is general agreement for up to a few
tenths of an inch across the area. There could even be some
isolated thunderstorms Tue aft/eve due to steepening lapse rates
with the upper trof overhead. It becomes much more sketchy at the
end of the week with ridging aloft and likely capping. A frontal
system approaches from the NW, but will likely struggle reaching
the area. Chance of convection at this time is low.
Near seasonable temps at the onset of the period will become
unseasonably warm from mid week into the weekend with many
locations away from the coast getting into the lower 80s, possibly
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --Low pressure well to the east departs and weakens into tonight.
Another low will approach from the south Monday.
VFR conditions this afternoon and into tonight. Winds from the NE
will give way to cstl seabreezes, timing dependent on site
By evening, winds lighten. Patchy fog cannot be completely ruled
out for isolated mvfr visibility, but not included in most
forecasts at this time.
Winds will be from the north/northeast Monday morning.
.OUTLOOK FOR 18Z Monday through Friday...
.Monday afternoon...VFR...with possible shower for KSWF.
.Monday night-Tuesday...VFR, then good chance for showers and
possible thunderstorms late Monday night and Tuesday. Sub-VFR in
.Wednesday-Thursday...VFR. Except sub-VFR in possible scattered
showers/thunderstorms Thursday night into Friday.
-- End Changed Discussion --
Sca conditions will develop on the ocean today and subside tngt.
Winds may be mrgnl...but seas will build to at least 5-6ft. Seas
at Hudson Canyon were at 9ft. Elsewhere...winds blw sca lvls.
5 ft seas develop again on the ocean Mon ngt as another low passes
near the waters. Winds and seas will subside Tue night into Wed
with high pressure building across the waters.
Less than a 1/4 inch of rainfall is expected today. Showers Mon
afternoon into Tue will bring potentially a few tenths at a time
where they do occur.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ350-353-355.