Scientific Forecaster Discussion
fxus61 kokx 181418
Area forecast discussion
National Weather Service New York New York
918 am EST Thu Jan 18 2018
high pressure builds to the southwest through tonight, then well to
the south of Long Island Friday and Friday night, as an area of low
pressure passes well to the north of the region, then both of
these continue to move east on Saturday. A back door cold front
will pass through late Saturday night into Sunday, then lift
back slowly north as a warm front Monday into Monday night. A
stronger cold front will approach from the west late Monday
night, and pass through on Tuesday. A secondary cold front
approaches from the north on Tuesday night, then pushes to the
south on Wednesday.
Near term /until 6 PM this evening/...
updated temperatures to reflect latest observations. Otherwise
forecast on track.
Mostly sunny day other than some passing mid-high clouds this
morning (mainly over southern zones) as shortwave ridging
builds. Highs today should be around 5 degrees below normal.
West-northwest winds with occasional gusts 15-20 kt this afternoon with
wind chills in the teens to mid 20s.
Short term /6 PM this evening through Friday night/...
the 700-500 hpa shortwave ridging exits to the east this evening,
followed by a 700-500 hpa shortwave trough passing by overnight.
With the subsidence from the ridging this evening, and the main from
the shortwave staying to the north of the region, it should be dry
tonight. Could see some passing mid-high clouds overnight with the
shortwave, with the best chance over north zones. Lows tonight should be
around 5 degrees below normal, with wind chills from around 10 to 20
Weakening northern stream ridging at 700-500 hpa crosses the area
Friday, giving way to zonal flow aloft Friday night. With shortwaves
staying well to the north and S of the area, and dry low to mid levels,
it should be dry with minimal cloud cover during this time frame.
Highs Friday should be near to slightly below normal, and lows
Friday night around 5 degrees above normal.
Long term /Saturday through Wednesday/...
flow aloft will be mainly zonal this weekend between a flat
trough to the north and a ridge over the southeast. The
resulting return flow should give US a mild weekend, with highs
on Sat in the lower 50s, then 45-50 on Sunday with
approach/passage of a weak back door cold front.
High pressure will nose down into New England Sunday night into Mon
while a warm front associated with strengthening low pressure moving
NE across the plains states approaches. There is some question as to
amount of warming aloft that will take place with the front, and
some spotty light wintry precip is possible late Sunday night into
Mon morning, especially inland northwest of NYC. Precip chances should
gradually increase Mon afternoon/evening with the warm front
just off to the SW, and deep layer SW flow having begun after
passage of an upper ridge axis.
Models continue to trend later with moderate to locally heavy
rainfall ahead of a sfc cold front and negatively tilted upper
trough, and have pushed greatest chances ahead to daytime Tue. Temps
on Tue ahead of the front should be on the mild side, with upper 40s
inland and lower 50s NYC Metro/Long Island. Temps should cool down
thereafter for mid next week but still remain above avg, with
building high pressure after the cold frontal passage being a combo
of maritime Pacific and/or modified Continental polar origin.
Aviation /14z Thursday through Monday/...
high pressure builds south of the region through Friday.
VFR. Winds primarily north of 310 magnetic this morning, backing
mostly south of 310 near 18-19z.
New York Metro enhanced aviation weather support...
Detailed information, including hourly taf wind component forecasts,
can be found at: http:/www.Weather.Gov/zny/n90
Kjfk taf comments: gusts might be only occasional this morning.
The afternoon kjfk haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Klga taf comments: gusts might be only occasional this morning.
The afternoon klga haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kewr taf comments: occasional gusts to around 20 kt possible
before 18z. Winds potentially prevail south of 310 magnetic all
The afternoon kewr haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.
Kteb taf comments: occasional gusts 16-19 knots possible this
Khpn taf comments: occasional gusts 16-19 knots possible this
Kisp taf comments: gusts might be only occasional this morning.
Outlook for 12z Friday through Monday...
Friday...VFR. West-SW winds g15-20kt possible.
Saturday...VFR. West-southwest winds g20-25kt.
Monday...MVFR or lower possible in -shra, mainly late.
a moderate pressure gradient remains over the waters through
Friday night, with sustained winds up to 20 kt and gusts up to
30 kt on the coastal ocean waters and 15 kt with gusts up to 20
kt on the non-ocean waters. Seas on the coastal ocean waters
fall to below 5 ft by Friday morning, there also could be a few
hours with gusts below 25 kt on the coastal ocean waters late
tonight and early Friday morning. As a result, have extended the
Small Craft Advisory on the coastal ocean waters through tonight. At this time,
confidence is not quite high enough to extend it into Friday.
Small Craft Advisory conds likely on the ocean east of Fire Island Inlet Sat into Sat
evening as a moderate west flow prevails between low pressure well to
the north and high pressure to the south. As a back door cold front
approaches and then passes through later Sat night into Sunday,
quiet conds expected on all waters thereafter into late Mon night,
when winds and seas on the ocean could again approach Small Craft Advisory conditions
in southeast-S flow ahead of an approaching cold front.
it should be dry through the weekend.
A frontal system passing through early next week has potential
to bring over an inch of rain during that time. Mainly nuisance
urban/poor drainage impacts expected at this time.
NYC National oceanic and atmospheric administration weather radio station kwo-35 (162.55 mhz) is off the
air for an extended period of time.
Marine...Small Craft Advisory until 6 am EST Friday for anz350-353-355.