Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 182024
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
324 PM EST Thu Jan 18 2018

.SYNOPSIS...
High pressure builds to the south on Friday. Low pressure
passes well to the north and east on Saturday. The low will send
a back door cold front through the region Sunday into Sunday
night. The front returns north as a warm front on Monday ahead
of a strong cold front passage late Monday night into Tuesday.
High pressure returns for the middle of the week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Upper level disturbance moving out of the Great Lakes passes to the
north tonight. It will pass through dry however the northern
zones may see mid and upper level clouds. Another cold night
with temperatures 5 to 10 degrees below normal in the teens to
mid 20s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Upper level trough swings out of the region early Friday with dry
weather continuing as high pressure builds across the South. A west
to southwest flow will advect in warmer temperatures with highs
expected to be near normal, in the 30s to near 40.

Temperatures fall into the 20s and low 30s Friday night under a
mostly clear sky.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
A split flow pattern is progged across the eastern states this
weekend with a developing storm system and upper trough over the
west. The flow over the northeast will be mainly zonal with a
relatively flat trough to our north. This pattern will yield above
normal temperatures and dry conditions on Saturday as readings reach
the upper 40s and lower 50s. It would not be surprising if highs end
up a few degrees warmer than currently advertised.

The flat trough to our north will have low pressure traversing
across southeast Canada on Saturday into Saturday night. Trailing
this low will be a back door cold front which should gradually sink
southward Sunday into Sunday night as high pressure attempts to
ridge down into New England. No precip is expected with this front,
but temperatures should be held down a few degrees from those on
Saturday. Highs on Sunday will be in the middle 40s for most
locations.

Upper jet stream pattern over the CONUS amplifies further Sunday
into early next week as the storm system over the west translates
into the central states by Monday. Upper ridge axis moves across the
region late Sunday night into Monday as well. The frontal boundary
to our south will gradually lift northward as a warm front on Monday
with low level warm advection and the ridge axis sliding to the
east. A warm nose should develop between about 750 and 900 mb as SW
flow increases ahead of the approaching upper trough. Main concern
with any precipitation will be for inland locations where surface
temperatures are slow to rise above freezing. The magnitude of the
warm advection and rising heights aloft would indicate any chance of
snow is limited with PTYPE concerns in the form of light freezing
rain or sleet. This appears to be confined to Monday morning across
the interior. Warmer air continues to move in Monday afternoon and
evening with temperatures getting into the upper 30s and lower 40s,
changing any mixed precip to plain rain.

There is divergence in model solutions Monday night into Tuesday on
the amplitude of the upper trough as well as the location of the
closed low and track of the surface low. Where confidence has
increased is with the progression of the cold front. Highest chances
for moderate to locally heavy rain continue to be late Monday night
into Tuesday morning in association with the cold front and best
dynamics from the upper trough becoming negatively tilted. Made some
minor adjustments to PoP timing, with a decreasing trend Tuesday
afternoon and evening as the front moves offshore. Highs on Tuesday
should reach the upper 40s and lower 50s.

Cooler air works back into the region for the middle of next week as
high pressure takes over with temperatures near normal.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
High pressure builds south of the region through Friday.

VFR. Winds vary around 310 magnetic this afternoon with gusts up to
around 20 kt. See comments below for details. Gusts subside near
22z.

     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: Winds favoring south of or at 310 magnetic.

KLGA TAF Comments: Winds favoring south of or at 310 magnetic.

KEWR TAF Comments: Winds favoring south of or at 310 magnetic.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.Friday aftn...VFR.
.Saturday...VFR. WSW winds G20-25KT.
.Sunday...VFR.
.Monday...Chance of MVFR or lower in -SHRA. S winds G20KT late day.
.Tuesday...IFR in rain. LLWS. S winds G25KT morning, W winds G30-
35KT aftn.

&&

.MARINE...
No changes to the marine headlines as SCA conditions will continue
into Friday morning with gusts on ocean waters to 25 kt. There could
be occasional gusts on Friday afternoon to 25 kt with seas just
nearing 5 feet on the eastern ocean waters, however confidence is
not high enough to extend the SCA into Friday afternoon at this
time.

SCA conditions are likely on the ocean waters on Saturday as a
relatively strong pressure gradient develops between high pressure
to the south and low pressure to the north. There is also a small
chance for a few gale force gusts. Have elected to leave out of the
HWO for now as confidence is low and they may end up only being
occasional. A few SCA gusts are also possible on the near shore
waters. More tranquil conditions are forecast on Sunday and Monday
with winds and seas below SCA levels. Winds increase to SCA levels
on late Monday night into Tuesday with a cold front passage.

&&

.HYDROLOGY...
Dry through the weekend.

A frontal system passing through late Monday night into Tuesday has
the potential to bring around inch of rain. No significant
hydrologic issues are anticipated at this time.

&&

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

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST Friday for ANZ350-353-355.

&&

$$
SYNOPSIS...CB/DS
NEAR TERM...CB
SHORT TERM...CB
LONG TERM...DS
AVIATION...JC
MARINE...CB/DS
HYDROLOGY...CB/DS
EQUIPMENT...


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