Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 231748
Area Forecast Discussion
National Weather Service New York NY
148 PM EDT MON MAY 23 2016
Low pressure off the Mid Atlantic coast moves slowly north
through tonight, then drifts northeast Tuesday and Tuesday night,
remaining offshore and passing south and east of the region. High
pressure will then briefly follow for Wednesday through Thursday
morning, then a cold front stalls in the vicinity Thursday
afternoon and night. The front returns north as a warm front on
Friday...followed by high pressure building in from the south
through the weekend.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Currently only 100-300 J/kg of CAPE to the N/W of NYC. For now
this is mainly to the N/W of a convergence line/weak surface
trough stretching from SE CT into NYC. The trough should lift to
the N/W later this afternoon, so given some additional daytime
heating and with some marginal low level instability (showalter
indices 0 to 4), there is the possibility for some isolated to
scattered showers mainly to the N of Long Island Sound/W of NYC.
Also cannot rule out isolated thunder across most of that area as
For highs today...still running a tad warmer than forecast hourly
temperatures...so bumped up highs a degree or so at most
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
The surface low continues to drift north and northeast tonight
through Tuesday night, remaining offshore, as the mid and upper
cutoff low also drifts along the coast. With the low a little
closer to the coast tonight and additional energy rotating
through, there will be a better, likely, chance of showers. There
may be isolated thunder early, however, cape and instability will
be decreasing. Not all areas will see precipitation, and will be
dependent on where the low and upper low drift.
Once again, Tuesday afternoon thunderstorms will be possible as a
surface trough develops and the low drifts east of the region.
Precipitation ends during Tuesday evening as the upper low begins
to fill and open, moving farther to the east, and height will be
rising at all levels after 03z Wednesday. Could be a rather sharp
end to the precipitation.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Ridging aloft on Wednesday will help slow down a cold front sinking
south across the Northeast. Insufficient moisture and lift should
therefore keep the CWA dry. Mixing to 850 mb, where temps are
forecast to rise to around 13C, along with a mostly sunny sky and SW
winds will bring high temps about 10-15 degrees above normal across
the entire area.
The cold front weakens and stalls over us on Thursday as ridging
aloft continues. Chance of afternoon tstms from around the city and
points west where better instability will reside. Subsidence will
limit mixing more than on Wednesday, so expecting high temps to be a
couple of degrees cooler on average versus Wednesday.
Friday and Saturday look to be similar days with ridging aloft and a
weak SE-S wind flow. This will probably limit chances of
showers/thunderstorms to inland sections both days, and chances
don`t appear to be very high due to limited moisture and/or capping
from ridging aloft. Models however hint at the possibility of an Mesoscale Convective System
moving through late Thursday night into early Friday morning, so a
more widespread rainfall is still a possibility. High temps both
days still averaging above normals in spite of a limited mixing
It appears that Sunday could feature deeper mixing,and along with
rising temps aloft, high temps could end up a few degrees warmer
than currently forecast. Didn`t want to stray too far from WPC
guidance this far out in time, which is warmer than Superblend.
Highs well into the 80s for some inland spots. Once again, limited
chances of showers/storms focused inland.
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --Low pressure off the Delmarva moves slowly NNE through Tuesday.
The sea breeze is advancing north and is currently located just
south of LGA. Where it hasn`t already, flow should shift to the
south over the next hour or two before becoming light and variable
tonight as the sea breeze circulation weakens. NNW winds develop
during the day on Tuesday before shifting to the WSW Tuesday
Mainly VFR thru this evening. Scattered showers have developed
across the Hudson Valley and should remain north and west of NYC
through the afternoon. An isolated thunderstorm cannot be ruled
out, particularly from the city into the Hudson Valley and
northeastern NJ. MVFR or lower in rain after 04Z, with MVFR
ceilings lingering into Tuesday afternoon.
...NY Metro Enhanced Aviation Weather Support...
Detailed information...including hourly TAF wind component fcsts can
be found at: http:/www.weather.gov/zny/n90
KJFK TAF Comments: Chance of an isolated shower or thunderstorm
KLGA TAF Comments: Chance of an isolated shower or thunderstorm
KEWR TAF Comments: Low prob of a thunderstorm this afternoon.
KTEB TAF Comments: Low prob of a thunderstorm this afternoon.
KHPN TAF Comments: A tempo may be needed for thunderstorms this
KISP TAF Comments: No unscheduled amendments expected.
.OUTLOOK FOR 18Z Tuesday through Saturday...
.Tuesday...periods of MVFR in -shra and/or tstms.
.Thursday night...low chance of MVFR -shra.
.Friday-Saturday...MVFR possible in tstms.
-- End Changed Discussion --
Made minor changes this update to reflect the latest trends in
observations and guidance. The forecast appears on track.
A rather weak pressure gradient force will be across the waters
through Tuesday night. Winds and seas will remain below small
craft levels through Tuesday night as a result.
Sub-sca conditions will prevail Wednesday through Friday as well, with
the lack of a strong pressure gradient or significant swell.
A long period of generally light precipitation is expected today
through Tuesday evening with 1/3 to 2/3 of an inch expected.
Locally higher amounts are possible if any thunderstorms develop
this afternoon and Tuesday afternoon.
Widespread significant rainfall is not expected for the rest of the