Area Forecast Discussion
Issued by NWS Upton, NY

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828
FXUS61 KOKX 290235
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1035 PM EDT Tue Mar 28 2017

.SYNOPSIS...
Low pressure will move southeast of Long Island tonight followed
by high pressure Wednesday through the day Thursday. Low
pressure approaching from the Central states will impact the
region Thursday night into Saturday. High pressure will build in
on Sunday and Monday. Another disturbance may affect the area
next Tuesday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Based on current observations and near term forecast trends,
only minor updates were made to the near term forecast.

The combination of both a weak upper level short wave and low
pressure just south of Long Island is producing widespread rain
and mainly light fog across the entire local area.

Radar estimated hourly rainfall rates up to .8 is likely causing
minor urban flooding of low lying and poor drainage areas across
the north shore of Suffolk County, NW of the sfc low.

Otherwise, the latest animated satellite imagery shows the back
edge of enhanced clouds across eastern NJ, where light rain is
still occurring.

Still holding with rain tapering off aft 03z W-E, ending by 09z
extreme east sections.

Used a guidance blend for lows tonight, with lower 40s invof
NYC, upper 30s most elsewhere, and isolated mid 30s well inland.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Dry weather with a northwesterly breeze. Despite a cooler deep
layer air mass in place, sfc temperatures will actually be
warmer than Tuesday because of deep mixing. Mostly sunny skies
are progged, with some fair weather Cu especially NW of NYC.
Took the high side of guidance for temps, with mid/upper 50s
most places, and upper 40s/lower 50s in the higher elevations.

Guidance may be underdone by quite a bit on winds for Wed
evening as low pressure off to the east intensifies. Model
soundings out east show winds 35-40 kt atop the mixed layer.
Trended forecast higher, with gusts up to 25 lasting until about
midnight.

Lows should be in the mid 30s invof NYC, lower 30s along the
coastlines and in the NYC suburbs, and 25-30 elsewhere.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
High pressure builds in for Thursday, then moves offshore Thursday
night. High temperatures on Thursday will be in the low to mid 50s.
Clouds will increase Thursday night as warm advection begins to move
in ahead of an approaching low pressure system. Expect periods of
rain starting Thursday night into Saturday. Some lingering cold air
across the northern portions of our CWA Thursday night may result in
a mix of snow and rain before warm advection increases. So have kept
the mix of snow and rain inland. High temperatures on Friday and
Saturday will be in the mid 40s to around 50.

Canadian high pressure builds in for late Saturday night into
Monday. Another disturbance may approach for Tuesday. Temperatures
during this period will be in the mid to upper 50s which is near
normal for this time of year.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Low pressure along a frontal boundary moves east of the region
overnight, with winds backing from NE to NW at near 10 kt or
less. High pressure builds in thereafter through Wednesday.

The conditions have begun improving after the exit of the bulk
of the rain as winds become more northerly. Mainly MVFR
conditions are occurring with some isolated VFR and IFR. As
winds become more NW early Wednesday, conditions will eventually
improve to VFR for all terminals. VFR for Wednesday overall but
with NW gusts near 20 kt during the day.

Amendments will be likely as categories forecast could vary from
observed by 1-2 categories at times tonight.

.OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...
.Wednesday night...VFR. N-NW gusts near 20KT subside early.
.Thursday...VFR.
.Friday...A wintry mix possible early north and west with IFR
conditions possible before a change to rain, otherwise sub VFR
conditions with rain elsewhere.
.Friday night and Saturday...Chance of rain with MVFR or lower
conditions. E winds G20-25KT at coastal terminals for Saturday.
.Sunday...VFR.

&&

.MARINE...
Winds and seas will remain below advy levels through tonight,
but could briefly come close on the ocean tonight as NE winds
increase on the back side of departing low pressure. Advy level
winds are also possible on the ocean on Wed in the morning.
Given the marginal nature of these winds, have not yet issued
SCA.

Gusts 25-30 kt are likely on all waters Wed night as low
pressure to the east intensifies and high pressure builds from
the west. Some 5-ft seas could linger into early Thu morning.

Potential for Small Craft Advisory conditions increases from
late day Friday through Saturday night with increasing
southeasterly winds ahead of an approaching system.

&&

.HYDROLOGY...
Additional basin average rainfall of 1/4 to 1/2 inch possible
into the first half of tonight as low pressure develops south
of Long Island and rain fills back in. Event total rainfall for
most of the area will be between 1/2 to 3/4 inch, with higher
totals above 1 inch on parts of Long Island where tstms passed
across earlier today. No additional hydrologic concerns
anticipated through tonight.

Additional rainfall of 1/2 inch to 1 inch is possible Thursday
night through Saturday. No hydrologic concerns anticipated.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides remain high due to a recent new moon. Water
levels may approach minor flood thresholds during the high tide
cycles tonight, with minor flooding possible Friday night as a
low pressure system approaches.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...GC/Fig/Goodman
NEAR TERM...GC
SHORT TERM...Goodman
LONG TERM...Fig
AVIATION...JM
MARINE...GC/Fig/Goodman
HYDROLOGY...Fig/Goodman
TIDES/COASTAL FLOODING...



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