Area Forecast Discussion
Issued by NWS Upton, NY-- Remove Highlighting --
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FXUS61 KOKX 201336
Area Forecast Discussion
National Weather Service New York NY
936 AM EDT SAT AUG 20 2016
A weak front will sit across the region today...and gradually
weaken into Sunday. Meanwhile, a frontal system will approach from
the Ohio Valley on Sunday and move through the region Sunday
night. High pressure then dominates next week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --A weak shortwave embedded in East coast ridging lingers over the
region today. At the surface...a weak backdoor front/trough linger
over the region.
The shortwave should provide trigger, and weak
front...differential heating...sea breeze...and outflow boundaries
should provide the focus for isolated to scattered shra/tsra
activity today in a marginally unstable airmass. Location of
shortwave axis across LI/CT appears to favor locations east of
Hudson River for convection.
Highs expected to be slightly above seasonable today in the lower
to mid 80s, except upper 80s NE Nj and parts of Lower Hud.
The threat for rip current development is low through early this
afternoon...but may become moderate late today with increasing se
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.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
Upper level ridge axis slides east tonight...with embedded shortwave
following suit. In it place a vigorous shortwave trough sharpening
over the Great Lakes tonight into Sunday...negatively tilts and
pivots through the Northeast US Sunday night into Monday.
At the surface...the weak backdoor front/trough appears to wash out
in the vicinity of the region tonight into Sunday. Would expect
diurnal shra/tsra activity to diminish tonight...but cant rule out
an isolated shra/tsra overnight. Patchy stratus/fog development
expected once again in maritime tropical airmass.
Meanwhile...a cold front associated with Canadian
low pressure...swings from the Ohio Valley tonight...towards the
region Sunday afternoon...and then through Sunday night.
Increasingly moist airmass expected on Sunday ahead of approaching
trough/cold front. Isolated shra/tsra possible late Sun morning into
afternoon if any lead shortwave energy available to provide a
trigger in an increasingly moist and marginally unstable airmass.
Otherwise...increasing clouds on Sunday...and very warm and humid
day. Increasing synoptic lift ahead of the pivoting
shortwave/upper jet streak and convergence of tropical moisture ahead
of the cold front...should have numerous showers and embedded
tstms approaching western portion of the Tri-state late Sunday aft
into Sun evening and then translating east across the region
Best forcing appears to be north and west of the Region...with
increasing shear in a weak instability environment. Main
convective threats appears to be torrential downpours with any
convection. The threat for strong to severe storms appears to be
quite low at this time due to late day/evening timing and weak
instability. If instability can build or line is faster...cant
rule out a storm or two with strong wind gusts for areas mainly west
of the Hudson late day/early eve. With strengthening low-level
veering wind profiles with weak wave development and low lcl`s
would have to monitor for rotating updrafts.
.LONG TERM /MONDAY THROUGH FRIDAY/...
Cold front pushes well offshore Monday morning. Behind the front
expect dry weather conditions as high pressure builds in from the
west and dominates through the end of the week.
Less humid conditions returns on Monday as dew points drop into the
low to mid 50s behind the front. Humidity levels will increase by
the middle of the week in response to an onshore flow with dewpoints
back into the mid 60s to upper 60s.
As for temperatures, expect near or slightly below normal
temperatures on Monday and through the middle of the week, then back
to above normal thereafter.
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --A weak frontal boundary remains nearby through the day.
VFR through the day today. KGON will have MVFR ceilings until around
16z, as stratus slowly lifts. Isolated showers/thunderstorms should
develop this afternoon along any boundaries, but coverage will be
too isolated to include in the forecast at this time. Amendments are
Patchy stratus and fog should redevelop after sunset tonight.
Local IFR possible after midnight.
Light NE winds become SE after 15z, and speeds increase to around 10
.OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
.Sunday...Chance of MVFR or less in showers and thunderstorms. SE winds
10-15 KT. Gusts 20-25 KT in the afternoon.
.Sunday night...MVFR or less likely in showers and thunderstorms.
.Monday...Chance of MVFR or less in shra/tstm early, then VFR
with NW Gusts 20-25 KT.
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Light winds are expected this morning before SE winds increase a bit
this afternoon. These SE winds persist through the day Sunday, and
will increase to 10 to 20 kt Sunday. A cold front moves across the
waters Sunday night, and winds shift around to the NW behind the
front Monday morning. A few gusts to 20 to 25 kt are possible.
High pressure builds Tuesday and Wednesday and winds lighten
Seas look to remain rather tranquil today and tonight. Ocean seas
may build slightly to 2 to 4 ft Sunday due to increasing winds.
However, elevated seas will subside early to mid week as the high
Only isolated to scattered showers and thunderstorms expected today.
Any thunderstorms that develop will be pulse type and nearly
stationary and therefore present a localized minor flooding
threat...with a low prob for flash flooding.
Sunday afternoon through Sunday night, 1/2 to possibly 1 inch of
rain is expected. Minor urban flooding would be the main
hydrologic impact from this rainfall...with a localized flash
flooding threat from any training cells.