Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kokx 221646 
afdokx

Area forecast discussion
National Weather Service New York New York
1246 PM EDT Tue Oct 22 2019

Synopsis...
a frontal system approaches today and passes across the region
tonight. High pressure follows Wednesday and Thursday. Weak low
pressure then approaches on Friday and passes through Friday
night. High pressure returns for most of the weekend with a
weakening system approaching by Sunday night into Monday.

&&

Near term /until 6 PM this evening/...
forecast is mainly on track with light rain or drizzle across
much of the area. Pops will increase a bit late in the day as
a cold front nears, but much of the widespread rain should
hold off until after 6pm.

An occluded and vertically stacked low pressure system over the
upper Midwest will lift into Ontario today. A frontal system
associated with the low will slowly approach from the west through
the day. High pressure over the Canadian Maritimes also ridges down
the New England coast ahead of the front.

Temperatures will remain steady through the afternoon with
abundant cloud cover, in the upper 50s to around 60.

&&

Short term /6 PM this evening through 6 PM Wednesday/...
the front will move across the tri-state tonight. A weak wave of low
pressure may develop along the front as shortwave energy rounds the
base of the upper trough. Strengthening low level S-SW winds ahead
of the front are also expected. These ingredients support a band of
rain tonight. The steadiest rain is forecast to occur from around
00z to about 06z for much of the area. The rain will begin to taper
off from west to east after 06z, ending across eastern Long Island
and southeast Connecticut around daybreak Wednesday. Rainfall
amounts range from 0.50 to 0.75 inches, highest north and west of
NYC. Soundings indicate little to no instability, so thunder has
been left out of the forecast.

The front quickly moves offshore by daybreak Wednesday. High
pressure will build to our south and west through the day. The
atmosphere dries out quickly and mostly sunny skies are anticipated.
Temperatures should be able to warm a few degrees above normal in
the lower and middle 60s for highs.

&&

Long term /Wednesday night through Monday/...
high pressure builds in Wednesday night with its ridge axis shifting
through on Thursday before it weakens offshore into Thursday night.
A mostly clear sky will prevail through the period with temperatures
within a few degrees of normal. Some frost may form Wednesday night
in some of the outlying suburbs with good radiational cooling
conditions.

Sided with wpc/ECMWF/Canadian regarding the weather pattern for
Friday and Saturday. Operational GFS differs, but gefs mean surface
progs appear to give better support to wpc/ECMWF/Canadian. A weak
low and jet streak dynamics bring low chances of showers Friday
afternoon and evening, then high pressure builds in to keep Saturday
dry. A frontal system then approaches on Sunday with overrunning
showers possible ahead of a warm front. Rain chances then increase
Sunday night with the approach of the trailing cold front. The front
weakens as it runs into ridging aloft across the northeast on
Monday, but will include a slight chance of showers for the day.

&&

Aviation /18z Tuesday through Sunday/...
low pressure system and a cold front approach today and move
across the region tonight.

MVFR/IFR conditions have overspread the region and will remain
in place through much of the taf period. We will generally see
ceiling heights between 700-1500 ft for much of the afternoon
with widespread IFR or lower ceilings developing around 00z.

Light drizzle and showers have begun to develop at the western
terminals and will become more widespread during the afternoon.
A more steady rain is likely this evening and into the
overnight. In addition, expect some lowered visibility into the
afternoon.

NE-north winds averaging around 5-10kt. Winds veer more east-northeast late
afternoon and evening. Southerly winds prior to the frontal
passage will be possible in the late evening. Winds become
northerly behind the cold front between 06-12z Wednesday.

Conditions start to improve after 09z as the front crosses the
region, winds turn to the northwest, and drier air moves into
the area.



New York 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: amendments possible for ceilings and
visibility through the afternoon.

The afternoon kjfk haze potential forecast is yellow, which
implies slant range visibility 4-6sm outside of cloud.

Klga taf comments: amendments possible for ceilings and
visibility through the afternoon.

The afternoon klga haze potential forecast is yellow, which
implies slant range visibility 4-6sm outside of cloud.

Kewr taf comments: amendments possible for ceilings and
visibility through the afternoon.

The afternoon kewr haze potential forecast is yellow, which
implies slant range visibility 4-6sm outside of cloud.

Kteb taf comments: amendments possible for ceilings and
visibility through the afternoon.

Khpn taf comments: amendments possible for ceilings and
visibility through the afternoon.

Kisp taf comments: amendments possible for ceilings and
visibility through the afternoon.

Outlook for 12z Wednesday through Saturday...
Wednesday-Thursday...VFR. Chc west gusts 20-25kt on weds.
Friday-Saturday...chc MVFR and rain Fri PM into Sat am.

&&

Marine...
the Small Craft Advisory remains in effect on the ocean waters
through Wednesday evening. A cold front approaches today and
moves across the waters tonight. Elevated ocean seas will
continue through Wednesday, mainly due to easterly swells.
However, wind gusts on the ocean increase late tonight and could
reach 25 kt into Wednesday morning behind the front which may
help to keep seas elevated as swells diminish Wednesday. Seas
begin to subside Wednesday afternoon along with winds falling
below 25 kt.

Winds subside through Wednesday night with conditions falling below
advisory levels. A high pressure ridge and weak pressure gradient
then bring tranquil conditions across the waters Thursday, which
continues through Friday. Winds then pick up a little on Saturday,
but conditions should remain below advisory levels.

&&

Hydrology...
no hydrologic impacts are anticipated from 0.50 to 0.75 inches of
rain late today and tonight.

No hydrologic impacts are forecast Wednesday into the weekend.

&&

Tides/coastal flooding...
water levels during this afternoons high tide along the South
Shore back bays will likely fall short of minor coastal flood
benchmarks. No statements have been issued at this time based on
the latest forecast water levels.

&&

Equipment...
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) remains off the
air.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Small Craft Advisory until 8 PM EDT Wednesday for anz350-353-
355.

&&

$$
Synopsis...jc/ds
near term...cb/ds
short term...ds
long term...jc

National Weather Service Glossary of Abbreviations