Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 211255
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
855 AM EDT Sun Apr 21 2019

.SYNOPSIS...
Low pressure approaches today and departs Monday. Weak high
pressure briefly builds south of the area on Tuesday. A cold
front will move through early on Wednesday. A warm front will
move into the region Friday, followed by a cold front late
Friday into early Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Energy rounding rotating around the upper low over the
Appalachians is providing some light showers across Long Island
and southern Connecticut. Some upper divergence is also
supporting these showers. This lift will wane in the next few
hours as the showers push off to the northeast of the region.

Rain chances were then reduced this afternoon except northwest
of the NYC metro. Cold pocket aloft associated with the upper
low could produce a few showers across the interior this
afternoon. Do not see much in the way of lift further east this
afternoon and model soundings indicate the middle levels drying
out behind the energy this morning.

Clouds should decrease somewhat into the afternoon, but there
should still be a good deal of high clouds and possibly some
cumulus development in the afternoon with some heating. High
temperatures in the middle and upper 60s are forecast away from
the immediate coast, with temperatures in the lower 60s across
Long Island and southern Connecticut.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
The upr low consolidates off the VA/NC coast tngt, and helps to
develop a weak sfc low over the Atlc which will track nwd on
Mon. If there is enough llvl moisture across the cwa tngt some
pockets of -dz are possible, but otherwise it looks dry with the
mid lvl dry slot over the region. There remains a high lvl of
uncertainty for Mon despite the short term nature of the event.
The most likely outcome based on a track similar to the 00z
NAM/GFS/ECMWF is an area of rain developing over at least ern
portion of the cwa during the day. This would hold temps back
in these areas. Elsewhere, some sfc based weak instability
develops, and the mesoscale modeling shows the potential for
shwrs and tstms initiating off the higher terrain of the
Berkshires and Taconics on nely flow, and tracking into the wrn
portion of the cwa. High chance to likely pops have been
included in the fcst based on the currently expected scenario,
but with a slow moving upr low significant changes to the fcst
should not be unexpected. The NBM appeared too high with temps
across ern areas due to the rain chances on Mon, so it was given
a lesser weight in the fcst.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The upper level low will finally get a kick into Tuesday and
eject northeast. This should enable some ridging to work in from
the west during Tuesday. Some sunshine looks to be on tap for
Tuesday and fairly confident that it stays dry. Perhaps far
northeastern sections see a shower early in the morning, but
otherwise it should be dry.

The next shortwave and associated frontal boundary approaches from
the west Tuesday night. The timing appears on average to be a touch
slower so backed down POPs a touch Tuesday evening and the first
half of Tuesday night. Cannot rule out a few thunderstorms on the
leading edge of the precip shield as it approaches far NW zones
during Tuesday night with some instability in place. POPs then
increase into Wednesday morning as the front draws closer. For now
thinking that the front clears the area by Wednesday afternoon,
although timing difference do exist among the global models. After
collaboration with surrounding offices decided to keep slight
chance POPs in for late Wednesday due to model timing differences.

Dry conditions expected on Thursday with high pressure briefly
paying the region a visit down to our south. The latest guidance
however is suggesting that clouds will start to increase by late
Thursday as a warm front off to our west and south starts to
approach. This should lead to some light rain into late Thursday
night and Friday morning based on the latest timing. There are model
differences with the exact track due to upper jet stream
interactions with much of the global guidance from 12z keeping the
main surface feature south of the region into Friday. This really
will impact the nature of the precip with respect to onshore flow
versus more of a southerly flow and higher dewpoint air moving up
from the south. In any event the cold front associated with the
system should move through by early Saturday leading to improving
weather into the start of next weekend.  Overall temperatures will
average above normal on Tuesday further west across the region,
otherwise temperatures should be fairly close to normal through the
period.

&&

.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
Low pressure from the west will slowly move over the terminals
and weaken today.

VFR conditions expected for the TAF period for most terminals.
Showers have developed east of NYC. These showers and SE flow
could briefly produce IFR or MVFR ceilings. Showers decrease in
coverage late this morning/early afternoon.

S to SE with speeds 5-12 kt expected today. Winds become light
and variable tonight.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.Monday...Showers and MVFR possible. Isolated thunderstorms for
terminals north of NYC Monday afternoon into early Monday
evening.
.Tuesday...Mainly VFR. Chance of showers and MVFR at night.
Isolated thunderstorms near KSWF Tuesday night.
.Wednesday...MVFR or lower possible in showers.
.Thursday...VFR.

&&

.MARINE...
South to southeast winds will remain 15 kt or less through the day
today, and continue to lighten tonight as the pressure gradient
remains weak.

Rough ocean seas however will continue, so SCA across the ocean
waters will remain in effect. The non ocean waters will remain sub
SCA through the remainder of the weekend.

Rough seas will continue on the ocean waters through much of Tuesday
due to a south to southeasterly swell. Seas will range from 5 to 6
ft. through much of this period on the ocean resulting in SCA
conditions. Seas on the ocean will come down slightly late Tuesday
and Tuesday night, with marginal SCA conditions expected into
Wednesday due to seas at 4 to 5 ft. Sub SCA conditions are expected
on the non-ocean waters Monday through Wednesday.

&&

.HYDROLOGY...
No hydrologic impacts are expected through next week.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off
the air.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory for hazardous seas until 6 PM EDT Monday
     for ANZ350-353-355.

&&

$$
SYNOPSIS...12/JE
NEAR TERM...12/DS
SHORT TERM...12
LONG TERM...JE
AVIATION...BC/PW
MARINE...BC
HYDROLOGY...12
EQUIPMENT...


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