Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 291748
Area Forecast Discussion
National Weather Service New York NY
148 PM EDT FRI JUL 29 2016
Low pressure passes to the south and east of Long Island through
this afternoon. High pressure will then briefly build into the
region tonight into the first half of Saturday, giving way to low
pressure approaching from the Ohio Valley later in the day. This
low will pass to the north as a few waves of low pressure pass
along a frontal boundary to the south into early next week. High
pressure then returns for the middle of the week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Widespread rain is tapering off across the forks of Long Island
and southeast Connecticut. Clearing skies are making there way
east the Hudson River. Expect this clearing to continue eastward
through the afternoon.
Have bumped highs up a few more degrees from the city north and
west and across the interior. Temperatures are already in the
upper 70s and lower 80s, and middle 80s appear attainable here.
Further east, the slower clearing should prevent highs from
getting above the upper 70s and lower 80s.
Some instability is noted on high resolution models this
afternoon/early evening due to increased heating west of the city,
so have continued with a slight chance of showers. Have left out
mention of thunder as it appears instability will be marginal if
any showers develop.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Weak ridging builds behind the shortwave tonight with surface
high pressure building from the northwest. Lows will be near
seasonable levels, but remaining muggy.
Weak high pressure will remain over the region Saturday morning,
resulting in a dry Saturday morning. Models have trended quicker
with the next approaching shortwave, which may trigger scattered
showers and thunderstorms as early as Saturday afternoon. Eastern
LI and SE CT may be able to remain dry most of the day. Highs
also will be near seasonable levels.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Latest NWP guidance in fair agreement with the H5 pattern across
North America consisting of strong high pressure over the southwest
US...a Bermuda high over the western Atlantic and a mean trough
extending from west of the Rockies to the east coast this weekend.
Early next week the high out west expands back into the southern
Plains sharpening the trough east of the Mississippi. The trough
moves east of the area on Tue with upper level ridging building in
for the middle of the week.
Model trends over the past 24 hours have sped up the weekend
system with pcpn moving in during the day Sat. The shortwave is
lagging behind the RRQ of a 65kt upper jet...but could have decent
warm rain processes with PW`s around 2 inches. However...the GFS
looks suspicious aloft between 00z and 12z developing a coupled
vort max/min in the mid levels thus enhancing pcpn total at the
sfc. So...while there will likely be overrunning Sat night with a
frontal boundary to our south...the best dynamics associated with
the shortwave appear to pass to the N on Sun with the majority of
the rainfall likely remaining to our N with areas N and W of NYC
having the best chance to see pcpn. A few weak waves of low pres
does develop along the boundary Sun and Sun night...but they look
to pass too far S to have any real impact on the region. Have
remained with chc pops for most of the area during this time
except NW zones which will be closest to the upper jet and
shortwave energy. There is also uncertainty with the location of
the frontal boundary. EC is further N with it on Sun tracking the
waves directly over the local area.
Upper trough axis approaches Mon and moves through Mon night with
sct showers/thunderstorms expected during this time. An isolated
shower is possible on Tue although there may not be enough
moisture and we could be capped as upper level ridging begins to
The remainder of the week looks dry with increasing heat and
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --Rain pretty much over throughout NY airspace, and CIGs lifting
from MVFR to VFR. May take some time for eastern zones to lift,
but VFR throughout by 20Z.
In general, VFR conditions expected through the TAF period.
Exception would be for terminals away from KNYC, mainly
KHPN/KISP/KGON, where VSBY reductions to MVFR or lower in BR, is
possible late tonight through Saturday morning.
Weak low pressure approaches Saturday afternoon. For now, will
carry PROB30 groups for 30 hour TAF sits of KEWR/KSWF, as precip
should hold off until after 18Z, and not confident enough that
precip would reach KJFK prior to 00Z Sunday to have a PROB30 group
in KJFK TAF at this time.
...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: No unscheduled AMDs expected.
KLGA TAF Comments: No unscheduled AMDs expected.
KEWR TAF Comments: MVFR CIGs should lift to VFR by 19Z.
KTEB TAF Comments: No unscheduled AMDs expected.
KHPN TAF Comments: No unscheduled AMDs expected.
KISP TAF Comments: MVFR cigs could persist through 20Z.
.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
.Saturday afternoon...Scattered showers possible, mainly for
western terminals, late in the afternoon. VFR otherwise.
.Saturday night into Sunday...Chance of showers and possibly a
tstm. MVFR or lower conditions possible.
.Sunday night-Monday night...Chance of showers. MVFR conditions
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As the low moves south and east of the waters this afternoon,
occasional gusts on the eastern ocean waters up to 25 kt are
possible. These winds should weaken after 18z as the pressure
Winds and seas are then expected to remain below small craft
advisory levels through Saturday. Low pressure is forecast to
track south of the waters today with strengthening E/NE winds
through this afternoon. Winds and seas are forecast to remain
below SCA, but could gusts up to around 20 kt, especially on the
ocean waters east of Moriches Inlet. Winds diminish tonight as
high pressure builds across the waters.
Sub-advsy conds are then expected through the rest of the forecast
The next chance for organized rainfall Saturday into Sunday. Less
than an inch is expected.