Area Forecast Discussion
Issued by NWS Upton, NY
FXUS61 KOKX 251147
Area Forecast Discussion
National Weather Service New York NY
747 AM EDT WED MAY 25 2016
High pressure builds to the south, then southeast, through
tonight followed by a weak cold front crossing the area on
Thursday. This front then lifts north as a warm front Thursday
night, with high pressure building in behind the front through
Saturday night. A series of frontal boundaries then impact the
area from Sunday into Tuesday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Continued an SPS for patchy fog, locally dense at times, for
the Twin Forks of Long Island and portions of southern CT through
9 am. Looking at local web cams, it does seem to be improving
somewhat, however, given some of the recent observations, locally
dense fog is still occurring.
Otherwise, deep layered ridging builds in
today, with associated subsidence keeping cloud cover relatively
at bay, once any morning fog burns off, other than some passing
cirrus in the afternoon. It appears the subsidence should also be
strong enough to keep any convection at bay this afternoon over
the County Warning Area (CWA), so have gone with a dry forecast.
For highs today, a blend of mixing down from 825-775 hPa, per
BUFKIT soundings, NAM 2-meter temperatures, and a mixture of
MAV/ECS/MET guidance was used. Highs should be around 15 degrees
above normal. It would not be surprising if a location of two in
NE NJ, the Lower Hudson Valley and maybe even normally warmer
locations in NYC reached the 90 degree mark. The afternoon
seabreeze should prevent any record highs from being reached.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Deep layered ridging remains in control tonight and Thursday. It
will be dry tonight, with only some high clouds around. However,
a 700-500 hPa shortwaves passes over the top of the ridge, and
through the area Thursday afternoon. This, coupled with surface
based CAPE of 5000-1000 J/kg, Showalter Indices from -2 to 2, and
20-25kt of Bulk shear over roughly the NW 2/5 of the CWA, warrants
slight chance to chance pops in that region.
It should be noted that the ECMWF suggests that there should be
sufficient subsidence under the ridge to keep things dry
throughout the area on Thursday. The GFS however suggests fairly
extensive convection over roughly the NW 2/5 of the CWA, with the
NAM somewhat in between (though closer to the ECMWF than the
GFS). Noting, that in addition to the passing shortwave, will also
have a cold front sinking south into the region. Based on this, it
appears there is enough forcing to warrant pops at this time.
However, there is still the potential for no precipitation at all
For lows tonight, a blend of MAV/MET/ECS guidance and NAM 2-meter
temperatures was used, with values around 10-15 degrees above
normal. A blend of MAV/ECS/MET guidance, NAM 2-meter temperatures
and a mix down from 850-750 hPa, per BUFKIT soundings, was used
for highs on Thursday. Highs should be around 15 degrees above
normal, but probably a degree or so lower than today. If the more
extensive convection suggested by the GFS plays out, highs,
especially over western areas, might need to be lowered by at
least 5 degrees.
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Frontal boundary lifts north of the area as a warm front Thursday
night. A southerly flow and ridging aloft will allow for the
above normal temperatures to continue Friday and Saturday. It will
also mean a noticeable increase in humidity as inland areas will
see dewpoints into the lower to middle 60s by Friday afternoon,
mainly away from the coast. The relatively cool ocean waters will
keep temperatures and dewpoints down along coastal areas. However,
temperatures across central Nassau and Suffolk may reach the upper
70s to near 80 on both Friday and Saturday.
The warm front then approaches our area again late Saturday night
into Sunday morning as a back door cold front. High pressure behind
this cold front over southeastern Canada slips off the New England
coast and into the western Atlantic during this time period. This
high is weaker than in previous model runs, and thus will not push
as far into our area as previously forecast. This will help to keep
the frontal boundary in the vicinity through Monday morning.
Sunday`s temperature may be a difficult one depending on which side
of the front we will be on.
We will be warm sectored on Monday. However, clouds and will keep
A cold front then approaches for Tuesday.
Something to watch is the disturbance well off the Southeast coast.
Models show this disturbance moving inland over the Southeast coast
and having little, if any, impact for our area through the forecast
period. However, moisture from this system could make its way into
our area on Tuesday, but right now it looks like a low chance of
that happening. It is still a few days out with a good deal of
uncertainty in the forecast.
As far as rainfall, nothing looks organized for the long term.
There is a fair amount of moisture available given the humid airmass
and surface based CAPE values are high for the afternoons from
Friday through Monday, but lift does not look overly impressive.
Afternoon showers and thunderstorms are possible for areas north and
west of NYC Friday and Saturday. Then there is at least a slight
chance for the entire area on Sunday with the approach of the back
door cold front, which will remain in the vicinity through Monday.
Continued unsettled for Tuesday with the approach of the cold front
from the west. None of these days are expected to be a washout, just
passing showers and thunderstorms.
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
High pressure builds in today.
VFR, except reduced vsbys in BR/FG at some of the non-city terminals
Light/calm winds pre-dawn bcmg West 5 to 10 kt in the morning,
increasing 9-14 kt in the afternoon and backing slightly,
more so at the coastal terminals. Gusts 15-19 kt.
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: Occasional gusts 18-20 kt possible this
afternoon. Chance of sea breeze backing winds to South this
KLGA TAF Comments: Gusts might be only occasional. Winds might back
closer to 250-230 magnetic this afternoon.
KEWR TAF Comments: Gusts might be only occasional.
The afternoon KEWR haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.
KTEB TAF Comments: Gusts might be only occasional.
KHPN TAF Comments: Gusts might be only occasional.
KISP TAF Comments: Improvement back to P6SM could be off by
around an hour. Gusts might be only occasional. Winds might back
closer to 230-210 magnetic this afternoon.
.OUTLOOK FOR 06Z Thursday through Sunday...
.Wednesday night through Thursday...VFR.
.Thursday night through Friday morning...Mainly VFR but sub-VFR
possible in showers/evening thunderstorms.
.Friday-Saturday...MVFR possible in afternoon/evening tstms.
.Sunday...Mainly VFR, but sub-VFR in showers possible NW of NYC.
A Marine Weather Statement is now in effect for locally dense
fog, mainly near shore, for the eastern Long Island Sound and
Peconic and Gardiner`s Bays of Long Island through 7am.
Outside of afternoon seabreezes bring gusts to around 20 kt to the
New York Bight Region Today and Thursday, a light to moderate
pressure gradient over the area will keep winds to 15 kt or less
through Sunday. With no significant swell forecast, these
relatively light winds will keep seas below Small Craft Advisory
criteria as well throughout the forecast period.
Dry through Thursday morning. Scattered to Isolated Showers and
Thunderstorms, mainly from NYC on N/W Thursday afternoon/evening
could bring less than 1/2 inch of rain to that area.
There are no significant hydrologic impacts expected from Thursday
Night into early next week.