Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 220036
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
836 PM EDT Tue Mar 21 2017

.SYNOPSIS...
A cold front will move across tonight. High pressure moving
into the Great Lakes on Wednesday will then build across on
Thursday, and pass east Thursday night. A warm front will
approach on Friday and remain nearby through Saturday. A
backdoor cold front moves through Saturday night. Another
frontal system affects the region for the beginning of next
week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A digging trough will approach, with dry cold fropa late
tonight, followed by strong CAA/NW winds heading into daybreak.

Lows generally falling into the 20s interior and near freezing
for the coast tonight, with wind chills falling into the teens
by daybreak.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Upper trough will pivots through, as the front pushes offshore.
Brisk NW flow expected through the day with deep mixing and
tight pressure gradient between high pressure and a developing
Canadian Maritimes low. Frequent gusts 35-40 mph likely, with
isolated 45-50 mph gusts potential based on winds at top of
mixed layer.

Scattered afternoon instability Cu likely under the shortwave
late tonight through Wed morning, but downslope flow and
diminishing instability over the Great Lakes do not support
maintenance of flurry/snow shower activity locally.

Unseasonably cold temps expected on Wednesday, struggling to
rise much from morning lows during the day as cold air moves in. Highs
generally from the upper 20s to mid 30s.

Upper trough slides east Wed Night with high pressure building
from the west, with winds gradually diminishing. A well mixed
boundary layer should limit radiational cooling, but still
expect temps to fall to around 20 NYC metro and into the teens
elsewhere. If decoupling occurs, temps would likely drop well
down into the single digits inland with snow pack.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
There is some uncertainty in this time frame, especially Saturday
and Sunday with placement of a warm front/back door cold front.
Thereafter, there is uncertainty with an area of low pressure that
rides a frontal boundary for the beginning of next week.

High pressure moves over the region and pushes off the East Coast
Thursday into Thursday night. This will allow a warm front to move
toward the region on Friday. Ridging aloft over the Western Great
Lakes region Thursday night flattens as it moves east.

The warm front remains in the vicinity on Saturday. As previously
mentioned, there is some uncertainty with where the warm front will
be late Friday into early Saturday, which could lead to uncertainty
in temperature forecasts and amount of precipitation. However, the
warm front should move back south as a back door cold front Saturday
into Saturday night.

Thereafter, weak surface low over the mid-West moves toward the
region, riding along the cold front, then passes well south of the
region. 12Z Canadian and 00Z ECMWF are in good agreement with this
feature in placement and timing, while the 12Z GFS is too far north
and redevelops a second low offshore a bit too late.

With the frontal boundaries in the vicinity as well as a weak area
of low pressure passing south of the area, it will be fairly
unsettled for this time period. Temperatures should average below
normal, with the exception of Saturday when we will see slightly
above normal temperatures with the warm front north of the area.
Again, there is some uncertainty with temperatures due to
exact placement of the front.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
A cold front will move southeast across the area late tonight.
Canadian high pressure will follow on Wednesday.

VFR. BKN mid and upper level clouds will precede the cold
front`s arrival overnight.

Winds along the South NY and CT coasts...S-SW winds 5-10 kt will
become W-NW by 02z at KJFK/KISP/KBDR/KGON.

Winds will increase to 15-20kt with G30kt following the CFP
overnight. The strongest winds will occur from 14Z-23Z Wed when
NW winds will be sustained near 25 kt with gusts to 35 kt. Wind
directions within 20 degrees of 320 degrees.

Timing of the CFP within 2 hours overnight.

...NY 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: No unscheduled amendments expected.

KLGA TAF Comments: No unscheduled amendments expected.

KEWR TAF Comments: No unscheduled amendments expected.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 18z WEDNESDAY THROUGH SUNDAY...
.Weds...VFR. NW Gusts 30-35 kt.
.Thursday..VFR.
.Friday...CHC PM shra/mvfr. SW gusts 25 kt.
.Saturday...Mainly VFR.
.Sunday...MVFR/IFR and rain. E gusts 20-25 kt.

&&

.MARINE...
Gales expected early Wednesday AM into Wednesday evening due to
tight pressure gradient and strong CAA in wake of cold frontal
passage late tonight, with building to 4-7 ft on the ocean
and3-5 ft on Long Island Sound. Winds should gradually diminish
through advy levels Wed night into Thu morning, and then remain
below through Thursday night.

Thereafter, gusts 25-30 kt are possible late Friday into Friday
night for the ocean waters as a warm front approaches. Winds
should fall below SCA criteria Sat through Sunday. SCA winds are
possible on the ocean waters late Sunday night through Monday
night as weak low pressure passes south of the waters. Seas
below 5 ft through Friday should build up to 6 ft on the ocean
Friday night, then diminishing below advy criteria by Saturday
morning. Ocean seas close to advy levels are also possible from
Sunday night and beyond.

&&

.FIRE WEATHER...
NW winds of 15-25 mph with gusts 35-40 mph and min RH in the 20s
should help dry fine fuels across the snow barren grounds of
Long Island coastal SE CT. This will enhance the threat for
brush fire spread in those areas.

&&

.HYDROLOGY...
Between 1 and 2 inches of QPF is possible this weekend into
early next week. However, this will fall over an extended
period of time and no hydrologic concerns are anticipated.

&&

.CLIMATE...
The following are record low temperatures for Thursday March
23, 2017 along with the forecast low temperatures.

Record Low Temperature          Forecast Low Temperature
----------------------          ------------------------
Central Park........12 (1875)    18
LaGuardia...........20 (1959)    21
Kennedy.............20 (1959)    20
Islip...............15 (2004)    15
Newark..............13 (1934)    17
Bridgeport..........19 (2004)    15

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Gale Warning from 6 AM Wednesday to 2 AM EDT Thursday for
     ANZ330-335-338-340-345-350-353-355.

&&

$$


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