Area Forecast Discussion
Issued by NWS Upton, NY-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 290808
Area Forecast Discussion
National Weather Service New York NY
408 AM EDT FRI JUL 29 2016
Low pressure approaches from the southwest tonight and passes
through the region Friday. The low departs late in the day Friday
with high pressure building to the north. Weak high pressure
briefly builds into the region for parts of Saturday. Unsettled
weather returns Saturday night through Sunday night with the
passage of another low pressure system. Drier weather is expected
for the first half of next week.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
The widespread area of heavy showers and thunderstorms have
weakened over Orange County, all that remains is some light rain
over the Lower Hudson Valley and Northeast New Jersey. An area of
light to moderate rain moving into Northwest New Jersey moving
northeast should move into the area over the next couple of hours.
Since much of the rain is not associated with thunder, took
mention of scattered thunderstorms out and went with isolated
instead. Otherwise, only minor changes made.
A coastal trough remains along with a deepening low over
Virginia. This low is associated with the vigorous shortwave
moving through the northern trough over the eastern states. A
combination of the deepening low and warm frontogenesis through
southern NJ to south of Long Island 03z to 06z will bring
increasing chances for showers, and with marginal instability
thunderstorms. A deep layered southwest flow around sub tropical
high pressure off southern coast and into the northern stream
trough was transporting tropical moisture into the region. There
will be potential for heavy rain developing later this evening
and overnight as lift increases with the frontogenesis. A flash
flood watch has been posted to this evening and into Friday.
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
Timing and tracking of the deepening low across the region during
Friday is still somewhat uncertain, although there is now more
consistency with the low tracking just south of Long Island
Friday afternoon. Increasing shear along the warm front late
tonight into Friday afternoon will increase the threat of severe
storms across metro NYC, Long Island, and into coastal CT, along
with continues heavy rainfall. Speed of the low has increased and
precipitation is now expected to taper off from the west during
the afternoon. Weak ridging builds behind the shortwave late
Friday into Friday night with surface high pressure building from
the northwest. Friday night will be dry with a cooler airmass
moving into the area.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Weak high pressure will remain over the region Saturday morning,
resulting in a dry Saturday morning. An approaching shortwave may
set off a few scattered showers and thunderstorms Saturday
afternoon, mainly west of NYC. East of NYC, conditions appear to
remain mostly dry. The unsettled weather becomes more widespread
Saturday night into Monday, as the shortwave and its associated low
pressure system moves across the region. Expect showers and
thunderstorms, through this time frame with some storms producing
locally heavy rainfall.
High pressure builds back into the region early next week, providing
mostly dry conditions. A few isolated showers or thunderstorms
cannot be ruled out during the first half of next week...mainly N
and W of NYC during the afternoon hours.
Temperatures will remain seasonable through the long term with
highs each day climbing into the 80s.
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --Low pressure along the Mid Atlantic coast will pass to the south
today. Associated bands of heavy showers with IFR vsby have
already taken shape from just north of NYC into northern NJ,
eastern PA, and northern MD. KTEB/KHPN have already experienced
IFR and brief LIFR vsby with the heavier activity, and think most
of this activity will remain there and at KEWR through about 10Z,
then move eastward and impact all of the NYC metro terminals plus
KHPN from about 10Z until at least 14Z, and KISP/KBDR from 11Z to
at least 15Z. LIFR conditions at KGON attm should improve to IFR
as rain arrives there by 12Z and continues until at least 16Z.
Occasional rumbles of thunder not entirely out of the question.
These showers could last a couple of hours longer than outlined
above, then a slow improvement to VFR expected this afternoon.
NE winds could gust between 15-20 at the coastal terminals this
.OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY...
.Late Fri night into Sat morning...Light fog with MVFR vsby
possible...then VFR late Sat morning.
.Sat afternoon into Sunday...Chance of showers and possibly a
tstm. MVFR or lower conditions possible.
.Sunday night-Mon night...Chance of showers. MVFR conditions
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Winds and seas are expected to remain below small craft advisory
levels tonight through Friday. A wave of low pressure is forecast
to track through or near the waters Friday. Depending on the track
of the low briefly higher winds and seas near small craft levels
will be possible on the ocean waters east of Moriches Inlet.
Showers and thunderstorms will be possible from this evening
through Friday. Some of the thunderstorms Friday may produce gusty
winds in excess of 35 KTS, especially over the ocean waters. At
this time fog formation is not expected.
A light pressure gradient over the area waters will result in sub-
sca conditions this weekend and early next week. However, any
thunderstorms that develop on the waters may produce brief SCA
A flash flood watch is in effect for the entire CWA tonight
through Friday for the potential of 2 to 4 inches with locally
higher amounts. The axis of heaviest rain at this time is expected
across northeastern New Jersey into the Lower Hudson Valley and
NYC, and into southwestern Connecticut. Uncertainty remains as to
where the heaviest rain occurs and depends on the track of low
pressure through the region. Also, the speed of the low will
affect the timing of precipitation.
Another round of showers and thunderstorms can be expected Saturday
night through Sunday...with some storms possibly producing heavy
rainfall. Exact precipitation amounts are unclear at this time.
-- Changed Discussion --CT...Flash Flood Watch through this afternoon for CTZ009>012.
NY...Flash Flood Watch through this afternoon for NYZ071>075-
NJ...Flash Flood Watch through this afternoon for NJZ004-006-
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