Scientific Forecaster Discussion
fxus61 kokx 201145
Area forecast discussion
National Weather Service New York New York
745 am EDT sun Aug 20 2017
high pressure will build into the region today, and then
settle 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
Near term /until 6 PM this evening/...
vigorous shortwave continues to pivot northeast of the region
this morning with associated cold front continuing to push well
offshore. In its wake, zonal upper flow develops with high
pressure building in from the west.
Deep northwest 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 south
There is a moderate risk for rip current development for east 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/New Jersey 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
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
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 southeast from central Canada through the midweek. This
will provide mostly sunny, dry and unseasonably cool conditions to
end the week into the weekend.
Aviation /12z Sunday through Thursday/...
high pressure will build in for much of the taf period, moving
offshore late in the period.
VFR through the taf period. A westerly flow will dominate during
the taf period. West-northwest flow 10kt gusting between 15 and 20 kt
today will subside tonight into Monday with winds decreasing to
less than 10 kt.
Coastal terminals, particularly kjfk could become more SW than
forecast late today. Chances of a true sea breeze that will be
directly onshore are low.
Outlook for 12z Monday through Thursday...
Monday-Tuesday morning...VFR. SW gusts to near 20kt Monday
late afternoon to early evening with sea breeze enhancement.
Tuesday afternoon-Wednesday...a chance of showers and
thunderstorms with MVFR or lower conditions possible. SW gusts
20-25kt Tuesday afternoon through Tuesday night.
sub-Small Craft Advisory 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 Small Craft Advisory gusts possible Tue aft/Tue
night with ocean seas building to Small Craft Advisory levels Tue night/Wed.
In the wake of the front, winds and seas are expected to fall
below Small Craft Advisory levels for late week as high pressure slowly builds
towards the area.
dry conditions through Monday.
Hydrologic impacts from potential showers and thunderstorms
Tuesday into Wednesday are uncertain at this point.