Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 220531
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
131 AM EDT Fri Mar 22 2019

.SYNOPSIS...
Low pressure passes nearby through this morning, then
intensifies as it moves slowly northeast toward the Canadian
Maritimes later this afternoon into Saturday. High pressure
builds to the south and west of the area through Sunday night,
followed by a cold frontal passage Monday. High pressure then
builds in through mid week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Based on latest observational trends as well as high resolution
model guidance, the main low will likely start to move ENE off
the NJ coast early this morning. There is a secondary piece of
energy just offshore that was been associated with convection
and moderate to heavy rain. It appears that in the next few
hours the low will begin to absorb this energy and track ENE off
NJ coast and then along or just south of the Long Island around
day break.

Periods of moderate rain to locally heavy rain will continue to
pivot northward through the early morning hours. Cannot rule out a
rumble of thunder across Long Island and possibly SE CT As the
low nears, middle level drying may temporarily diminish rain
across eastern sections. Wrap around rain bands may continue
however north and west of the city. It still appears that
rainfall rates would fall short of flash flood guidance, but
minor urban and small stream flooding remain possible.

Meanwhile, the 998MB surface low over the DELMARVA at 02Z will
strengthen and continue to track to the northeast overnight with
its center moving in overhead towards daybreak. Ahead of it,
lift from a LLJ and good moisture convergence and perhaps a
little instability aloft combine for moderate rainfall. The rain
could be heavy at times until these factors shift out of the
area late in the overnight. Can`t completely rule out a rumble
of thunder, but will leave out the mention of it due its low
probability and coverage. This will be mainly across the eastern
zones, however, the convective activity over the ocean waters
has been weakening as the area tracks toward Long Island.

Temperatures will drop off slightly this evening, but will remain in
the 40s for the most part.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
The surface will move east of Long Island in the morning and
intensify as it moves up the New England coast. Some colder air
may advect towards the interior in the morning on the backside
of the low, within some lingering wrap around bands. It would
not be surprising if a few higher elevations in the NW interior
saw some snow mixed in with rain. Temperatures should remain
above freezing, so no accumulation anticipated. Lingering
showers may continue into the afternoon as the low slowly moves
north and another vigorous shortwave/closed low approaches
aloft.

The cold pool aloft and approaching lift maintain a threat of
showers into the afternoon. WNW winds begin to increase in
response to the deepening surface low to the NE with gusts up to
around 35 mph possible in the afternoon. Highs range mostly in
the mid and upper 40s.

The shortwave/upper low shift through during the evening, bringing a
chance of PCPN to the entire area, which could be a mix of rain and
snow north of the city. Looks like only areas north and east of the
city would still have a chance of additional PCPN after midnight. It
remains breezy through the night with a gusty westerly flow
increasing, but likely remaining below advisory criteria. A few
gusts may still approach 45 mph.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A strong upper low lifts northward across the Canadian Maritimes
on Saturday with shortwave ridging building in on the backside
Saturday night through Sunday. This will be short-lived though
as a polar vortex over Hudson Bay drops into eastern Canada.
The latter of which will send a strong cold front through the
region on Monday.

Gusty WNW winds will continue on Saturday due to a strong
pressure gradient between the departing low over the Canadian
Maritimes and high pressure building across the Ohio and
Tennessee Valleys. Gusts up to 40 kt will be possible in the
morning, but then begin to gradually subside through Saturday
night. High pressure builds to the south and west of the area
Sunday, then gives way to a strong cold front on Monday. There
are subtle timing differences, but consensus supports a late
morning into early afternoon passage. There is a chance of a
light post-frontal rain event, mainly in the afternoon, ending
along the coast by early evening. Upper trough at this time
looks to be too progressive for any phasing with a southern
branch shortwave trough that passes to the south. This will be
watched in subsequent days.

More importantly, an anomalously cold airmass moves into the
area Monday night into Tuesday. After highs in the 50s Sunday
and Monday, readings will struggle to get into the lower 40s on
Tuesday. Airmass will then gradually moderate through Thursday,
but remain dry.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Low pressure moves to the northeast today.

Winds will back to the N around the morning push, then W/NW by
afternoon. Speeds may diminish briefly this morning as the low
tracks just south of Long Island, then pick up as the low pulls
away. Gusts around 20-25 kt are expected this morning, then
25-30 kt this afternoon.

Rain persists this morning, varying in intensity. A period of
LIFR conditions is possible from about 08Z-13Z invof the low.
Improvement to MVFR, then VFR 15Z-18Z as the low pulls away.

Sct rain/snow showers possible after 18Z which could produce
brief local MVFR or lower conds. Coverage and timing is too
uncertain to include in TAF.

.OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY...
.Late tonight...Potential for MVFR or lower at times in rain or
snow showers. W winds G30-35kt.
.Saturday...VFR. NW winds G25-35kt.
.Sunday...VFR.
.Monday...MVFR or lower late with a cold frontal passage.
.Tuesday...VFR.

&&

.MARINE...
No changes to winds and seas at this time.

SCA conds expected on all waters early this morning, but there
may be a gust or two on the ocean that approach gale force due
to the tightening pressure gradient and llj shifting through.
Winds otherwise diminish towards daybreak with the low center
passing overhead. Winds then ramp up behind the system, with
Gales bcmg likely at least on the ocean during the afternoon.
Occasional gale gusts are possible on the other waters, but it`s
not until Friday night where gales here will be likely. Gale
warnings have been issued accordingly and go through Saturday
afternoon.

Gales continue into Saturday with a WNW flow gradually
diminishing Saturday afternoon through Sunday. Sub-SCA
conditions then return Sunday into Monday. Marginal SCA
conditions are possible Monday night into Tuesday morning with a
strengthening northerly flow behind a cold front.

&&

.HYDROLOGY...
An additional half inch to inch of rain is expected early this
morning. This could result in some minor poor drainage and
small stream flooding. Showers may continue at times later this
morning into the afternoon, but overall amounts will be light
and no impacts anticipated.

No hydrologic impacts anticipated Friday night through early next
week.

&&

.TIDES/COASTAL FLOODING...
High tide has passed along the south shore bays of Nassau,
Queens, and NY Harbor. High tide has yet to pass for western
Long Island Sound where minor coastal flooding is expected
early this morning.

This morning, winds weaken and begin to switch offshore. Surge
will be subsiding, but will be slow to occur in the south shore
bays. Widespread minor coastal flooding likely for southern bays
of Queens and Nassau, while localized minor impacts likely for
E Great South bays, W LI Sound and NY Harbor. This should be the
final tide of concern.

&&

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

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory until 2 AM EDT early this morning for
     CTZ009-010.
NY...Coastal Flood Advisory until 2 AM EDT early this morning for
     NYZ071-073-078-177.
     Coastal Flood Advisory from 8 AM this morning to 1 PM EDT this
     afternoon for NYZ075-178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ330-
     335-338-340-345.
     Gale Warning from 6 PM this evening to 6 PM EDT Saturday for
     ANZ330-335-338-340-345.
     Small Craft Advisory until 6 AM EDT early this morning for
     ANZ350-353-355.
     Gale Warning from 6 AM this morning to 6 PM EDT Saturday for
     ANZ350-353-355.

&&

$$
SYNOPSIS...JC/DW
NEAR TERM...DS/19
SHORT TERM...JC/DS
LONG TERM...DW
AVIATION...Goodman/PW
MARINE...JMC/19/DW
HYDROLOGY...JMC/DW
TIDES/COASTAL FLOODING...
EQUIPMENT...


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