Area Forecast Discussion
Issued by NWS Upton, NY

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802
FXUS61 KOKX 200733
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
333 AM EDT Sun Aug 20 2017

.SYNOPSIS...
High pressure will build into the region today, and then
settles to the south and east Monday through Tuesday. A frontal
system approaches Tuesday Night and crosses the region
Wednesday. Canadian High pressure then builds in through
Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Vigorous shortwave pivots northeast of the region this morning
with associated cold front pushing well offshore. In it wake,
zonal upper flow develops with high pressure building in from
the west.

Deep NW flow and subsidence will result in a sunny, comfortably dry,
and seasonably warm day today. Highs generally in the lower to
mid 80s. Late day sea breeze possible along the immediate coast.

There is a moderate risk for rip current development for E LI
beaches due to lingering 3 ft @ 6-7 sec swells.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
Zonal upper flow continues into Mon, and then begins to back a bit
Tuesday ahead of a longwave trough digging into the Great Lakes.

At the surface...high pressure gradually translates to the south and
southeast tonight into Monday morning. Good radiational cooling
conds tonight, with lows in the 50s across far outlying areas. 60s
to around 70 elsewhere.

As the high builds south and east, heat and humidity will build into
the region Monday into Tuesday. Highs will generally be well into
the 80s to around 90 on Monday, and upper 80s to lower 90s for
Tuesday. Low prob of heat advisory for portions of the NYC/NJ metro
on Tuesday as humidity levels climb.

Models are indicating potential for isolated diurnal convection
(along sea breeze boundary or hills) on Tuesday as instability
increases and convectively induced vort energy rotates around the
upper ridge. Low predictability on convective details at this
point.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Longwave trough digs into the Great Lakes Tue into Tue Night and
then slides into the NE US for the mid to late week. An associated
frontal system interacting with a sub-tropical airmass will bring
the next chance for organized shower and tstm activity Tue Night
into Wed. Low predictability on the convective details at this
point...contingent on timing of front/forcing with diurnal
instability.

Then a significant cool down expected for the end of the week as the
long wave trough settles into the NE US, and Canadian high pressure
slowly builds SE from Central Canada through the midweek.  This
will provide mostly sunny, dry and unseasonably cool conditions to
end the week into the weekend.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
Following a weak cold frontal passage, high pressure will build
in for the remainder of the TAF period.

VFR through the TAF period. Winds will be near 10 kt or less.
Flow becomes more NW into this morning and then W-SW in the
afternoon with the more SW flow at coastal terminals,
particularly KJFK. Flow generally becomes more NW tonight.

.OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
.Late Tonight-Tuesday Morning...VFR. SW gusts to near 20kt
Monday late afternoon to early evening.
.Tuesday Afternoon-Wednesday...A chance of showers and
thunderstorms with MVFR or lower conditions possible. SW gusts
20-25kt Tuesday afternoon through Tuesday night.
.Wednesday Night-Thursday...VFR.

&&

.MARINE...
Sub-SCA conditions expected through Tuesday afternoon as high
pressure traverses southeast through the waters.

Winds and seas will increase ahead of a cold frontal Tuesday
into Tuesday Night. Marginal SCA gusts possible Tue Aft/Tue
night with ocean seas building to SCA levels Tue Night/Wed.

In the wake of the front, winds and seas are expected to fall
below SCA levels for late week as high pressure slowly builds
towards the area.

&&

.HYDROLOGY...
Dry conditions through Monday.

Hydrologic impacts from potential showers and thunderstorms
Tuesday into Wednesday are uncertain at this point.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...Maloit/NV
AVIATION...JM
MARINE...NV
HYDROLOGY...NV



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