Scientific Forecaster Discussion
fxus61 kokx 222052
Area forecast discussion
National Weather Service New York New York
352 PM EST Mon Jan 22 2018
a warm front continues to push north tonight. A cold front will
approach from the west tonight, then cross the region Tuesday.
High pressure builds in for the rest of the week, followed by a
frontal system over the weekend.
Near term /until midnight tonight/...
for the remainder of tonight expect spotty drizzle with areas of
fog across the area with above normal temperatures. Low
temperatures tonight will be in the upper 30s to lower 40s.
Short term /midnight tonight through Tuesday night/...
as a warm front continues to push north tonight and into
Tuesday a deep moisture airmass along with precipitable water
values of 1 to 1.25" will set the stage for periods of moderate
to locally heavy rainfall, as a cold front approaches late
tonight and moves across the area Tuesday morning. The front is
forecast to move through fast, so the heavy rainfall at this
time doesn't seem to be a significant threat.
There will be some good instability ahead of the approaching cold
front. Will continue the mention for an isolated thunderstorms as
the cold front makes its way across the area. There is also the
potential for strong winds above the surface to mix down in any
thunderstorms. Regardless, a tight pressure gradient will lead to
strong winds across the area through the day but at the moment it
appears winds will be brief and sporadic enough to preclude a Wind
Advisory for now.
The front will pull offshore by Tuesday evening. Northwest winds
behind the front will usher in more seasonable temperatures. Tuesday
nights low will be in the low to mid 30s.
Long term /Wednesday through Monday/...
not much change in the 12z data regarding the long term. High pres
builds in from the W on Wed, with WNW winds ushering in a colder
airmass. Deep mixing provides a high confidence in temps, so a blend
of the data was used. There could be a period of bkn-ovc aftn cu
which the model data is not picking up on attm, so an upgrade in
cloud cover is possible with subsequent updates.
With deep unidirectional flow, winds should keep the lowest lvls
mixed Wed ngt. Temps therefore not as cold as a pure MOS blend.
Still breezy on Thu but deep subsidence will produce a sunny day.
The superblend was used for temps.
Still in the cool regime Fri as return flow does not commence til
late in the day. The superblend again used for temps. Some mid clouds
may infiltrate the skies if the waa aloft develops fast enough.
A warming trend on Sat as a frontal sys approaches. The GFS and
European model (ecmwf) have diverged on timing however, with the European model (ecmwf) now about 24
hrs slower than the GFS, bringing the cdfnt and bulk of the rain in
on Mon. The fcst remains close to the more consistent timing of the
GFS, with pops focused on sun and sun ngt. Lower pops remain in
place for Mon, but again this could change if the European model (ecmwf) becomes a
trend. The superblend was used for temps.
Aviation /21z Monday through Saturday/...
difficult forecast for the NYC and Long Island terminals as a
warm front just to south of the area this afternoon lifts
through late tonight. For the NYC and Long Island terminals.
Ceilings will likely remain VFR, but an occasional MVFR ceiling
can not be ruled out. For the Connecticut and lower Hudson
Valley terminals, there is higher confidence for MVFR ceilings
becoming IFR toward evening. IFR ceilings are forecast to
develop across the remaining terminals late tonight. Any
improvement tomorrow is forecast to be gradual. Moderate to
heavy rain showers and isolated thunderstorms will impact the
area from daybreak through the afternoon with the approach of a
Winds will be east/NE at 5 kt or less, except for those terminals
near Long Island Sound where the flow will be closer to 10 kt
this afternoon. Winds veer to the southeast then S late tonight into
Tuesday morning as warm front pushes north of the region.
Low level wind shear/compression likely Tuesday with gusts up to 35 kt possible,
strongest for kisp/kgon. Cold frontal passage with wind shift
to west will occur from mid to late afternoon.
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: low confidence of MVFR conditions for the
Klga taf comments: low confidence of MVFR conditions for the
Kewr taf comments: low confidence of MVFR conditions for the
Kteb taf comments: occasional MVFR ceilings possible late this
afternoon/early this evening.
Khpn taf comments: IFR conds likely by this evening.
Kisp taf comments: low confidence of MVFR conditions by this
Outlook for 18z Tuesday through Saturday...
Tuesday afternoon...IFR/LIFR in shra, with isolated thunderstorm
possible. Low level wind shear/compression ending from west to east by evening.
Gusts up to 35 kt possible, strongest for kisp/kgon. Wind shift
to west late.
Tuesday night into Wednesday...VFR. West-northwest g20-25kt.
Saturday...showers possible with S-SW g20kt.
south to southwest flow will rapidly strengthen across the area
waters tonight, with at least Small Craft Advisory level winds developing. Depending
on the strength of the inversion, there is potential for strong low-
level jet winds to mix to the surface, with at least occasional gale-
force winds on Tuesday. Occasional gale force winds will also be
possible in any thunderstorms that can develop. Seas will rapidly
build in response to the strengthened flow, remaining elevated even
as the cold front moves through Tuesday evening. Winds may briefly
drop off as the front moves through, before rapidly strengthening
again following its passage. Small Craft Advisory level winds in the 25 to 30 kt
range are expected.
A sca will be needed on the ocean Wed and Wed ngt. Winds will be
mrgnl elsewhere. Winds and seas will then creep up towards sca lvls
again on Thu as low pres deepens over the Atlc. Winds and seas blw
sca lvls on Fri, then SW flow increases over the weekend ahead of a
total rain Monday night through Tuesday is expected to range mostly
1/2 to 1 inch, with locally 1 to 2 inches possible. No significant
hydrologic issues are anticipated at this time.
No hydrologic impacts are anticipated Wednesday through early next
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 from 6 am Tuesday to 6 am EST Wednesday