Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 210914

Area Forecast Discussion
National Weather Service New York NY
414 AM EST Wed Feb 21 2018

High pressure over the western Atlantic remains in control today as
a slow moving cold front approaches from the west. The cold front
moves through tonight, stalling to the south on Thursday.
A series of lows and frontal boundaries will impact the area
late in the week and through the weekend. High pressure builds
early next week.


Dense fog continues to expand westward early this morning. The fog
shows up well on the GOES-16 nighttime fog product and nighttime
microphysics RGB. Surface observations support expanding the
dense fog advisory westward a bit and now includes all of Queens
and Brooklyn, Long Island, Westchester, Putnam southern
Connecticut. Will continue to monitor trends for further
expansion early this morning.

The atmosphere above 2 kft is very dry today, so suspect heating and
mixing will be sufficient to allow the fog/stratus to burn
off/lift a few hours after sunrise. A similar situation occurred
on Tuesday with much of the region seeing at least partly sunny
skies by late morning/early afternoon. Followed the same
overall idea, but with a slightly quicker progression. The only
exception is across eastern Long Island and southeastern CT
where at least patchy fog and/or stratus could linger into the

The main weather story for today will be the unseasonably warm
temperatures aided by an anomalously strong western Atlantic ridge.
The 00z OKX RAOB had an observed 500 mb height of 5880m, which well
above the max observed values for this time of year per SPC Sounding
Climatology webpage. In fact, it is higher than any observed value
for December through March. Suspect a similar 500 mb height will be
observed this morning on our 12z RAOB, leading to record high
temperatures. Better mixing compared to Tuesday will allow
temperatures to soar well into the upper 60s and lower 70s away from
the immediate coast where readings will be held down in the upper
50s and lower 60s from colder ocean influence. These temperatures
are more typical of normal highs in early May. See climate section
below for record highs for February 21.

A slow moving cold front moves into the region this evening with a
shower possible across the NW interior.


Western Atlantic ridge breaks just enough tonight to allow the cold
front to sink south of the region. Lift with the front is weak and
have limited PoPs to low chance for the first part of the night.
Temperatures will begin a decline as an approx 1043mb surface high
traverses across southeast Canada and begins to build across
northern New England. Cold advection will also take place aloft.
Temperatures should fall into the upper 30s inland and lower 40s
closer to the coast.

The cold front stalls across the southern Middle Atlantic on
Thursday. The anomalous western Atlantic ridge will still be
dominating the weather pattern across the eastern US, but its height
field over the northeast is progged to be a bit more suppressed.
Weakening shortwave energy will ride along the periphery of the
ridge. Warmer air between 850 and 750 mb will overrun colder
air below advecting south from the strong high to the north.
This sets up a period of precipitation from late Thursday
morning into Thursday evening. Much of the area will see a
chilly rain, but there could be some sleet mixing in across the
interior in the afternoon where the depth of the colder air is a
bit deeper. Will need to watch surface temperatures as there
are some hints that temperatures could come close to freezing in
the afternoon. Did not mention freezing rain in the forecast at
this time, but it may have to be introduced in subsequent
forecasts if colder temperatures look more likely.

Temperatures on Thursday will be 20-30 degrees colder than on
Wednesday. Daytime highs in the lower to middle 40s will likely
occur in the morning, with temperatures falling into the 30s in the


Quite an active pattern is expected through the weekend.

Deep SW flow prevails initially with ridge located over the
southeast, and trough over the western United States.

Sfc frontal boundary weakens as it sags south of the area Thursday
night, and lingering light precip temporarily tapers off as high
pressure builds to the north. An area of low pressure passes to the
north, dragging a warm front, occluded front to the north, through
Friday. A cold front quickly follows Friday night. Once again, the
front does not make much progress to the south, and the next low
pressure center approaches Saturday and Sunday. This is out ahead of
downstream trough that ejects out of the west and makes eastward
progress across the mid section of the country. The low tracks well
to the north, with a warm front passing, followed by a cold front
Sunday and Sunday night.

High pressure builds Monday and Tuesday.

Even though temperatures will be no where near the record readings
of the past couple of days, above normal temperatures are
anticipated though the period. Highest readings expected this
weekend ahead of downstream system when WAA ensues.

As for sensible weather, lingering light precip Thursday night will
be mainly in the form of rain, but a wintry mix of rain and sleet,
or freezing rain and sleet, is expected across the interior.

This is true for Friday morning as well if precip moves back in
early enough, but all locations should see plain rain when the bulk
of the precip arrives ahead of the warm front as temps warm.

When precipitation does occur this weekend, it will be in the form
of rain.


High pressure today gives way to a cold front tonight.

LIFR/VLIFR to start. Improving flight categories after 12-13z, with
VFR by afternoon. S winds bcmg SW this morning, around 10 kt.
G15-20KT possible this afternoon for KLGA, KEWR, KTEB, KHPN, KSWF.
Winds shift to the NW between 01z and 03z with gusts 15 to 20 kt for
NYC/NJ terminals.

...NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at:

KJFK TAF Comments: Timing of improving flight categories may be off
by 1-2 hours.
The afternoon KJFK haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.

KLGA TAF Comments: VSBYS may improve to 6+ SM along with cigs up to
900-1000ft at times thru 14z. Timing of improving flight categories
may be off by 1-2 hours.
The afternoon KLGA haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.

KEWR TAF Comments: Tempo LIFR might not occur this morning. Timing
of improving flight categories may be off by 1-2 hours.
The afternoon KEWR haze potential forecast is YELLOW...which implies
slant range visibility 4-6SM outside of cloud.

KTEB TAF Comments: Tempo LIFR might not occur this morning. Timing
of improving flight categories may be off by 1-2 hours.

KHPN TAF Comments: Timing of improving flight categories may be off
by 1-2 hours.

KISP TAF Comments: Timing of improving flight categories may be off
by 1-2 hours.

.Late Tonight...Chance of showers with MVFR. Subsiding N gusts after
.Thu...MVFR/IFR in rain likely. Rain/sleet mix for KSWF in the
afternoon and chc sleet/freezing rain at night. N/NE wind G15-20 KT
.Fri...MVFR/IFR in rain. chc morning sleet/freezing rain at KSWF.
.Sat...CHC MVFR in shra.
.Sun...MVFR/IFR in rain. S G20 KT.


A dense fog advisory remains in effect on all the waters through
15z this morning. With a persistent the southwest flow ocean
seas east of Fire Island Inlet remain 5 feet or a little higher
through tonight. Marginal SCA gusts are also possible on the
ocean this afternoon and evening ahead of a cold front. The cold
front moves to the south tonight with seas gradually subsiding
below 5 ft into Thursday morning. Sub-SCA conditions are likely
Thursday morning with ocean seas building above 5 ft and
marginal SCA gusts on the ocean in the afternoon.

Gusty east/northeast winds Thursday night will lighten as the winds
shift to the east/southeast late Thursday night and Friday.

A warm front passes as low pressure tracks well to the north,
followed by a cold front Friday into Saturday. The front settles
nearby, and moves back to the north as a warm front Sunday. Another
area of low pressure tracks well to the north late this weekend.
Winds pick up during this time, and seas build as well.


Episodes of light to moderate rainfall are possible Thursday
into the weekend. One to two inches of total rainfall is a
possibility, but the rainfall accumulations will occur over a
long duration. As such, no hydrologic impacts are anticipated at
this time.


Temperatures may approach or break record highs in a few spots
Tuesday and Wednesday.

Record Highs for Wednesday February 21, 2018

Central Park........68/1930

Record High Minimum Temperatures for Wednesday February 21, 2018

Central Park........50/2002


NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.


CT...Dense Fog Advisory until 10 AM EST this morning for CTZ005>012.
NY...Dense Fog Advisory until 10 AM EST this morning for NYZ068-070-
MARINE...Dense Fog Advisory until 10 AM EST this morning for ANZ330-335-
     Small Craft Advisory until 6 AM EST Thursday for ANZ350-353.


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