Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 261847
Area Forecast Discussion
National Weather Service New York NY
247 PM EDT Sun Mar 26 2017
High pressure centered over eastern Canada and extending into
New England and the northeast will gradually slide east today. A
stationary front well to the southwest will approach as a warm
front tonight and move into the area Monday. Another frontal
system affects the region Tuesday and Tuesday night. High
pressure builds to the west Wednesday and Thursday. Another low
pressure system approaches Friday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Center of Canadian high pressure gradually slides to the coast
by late in the day. Temps will run a good 5 to 10 degrees below
seasonable today with cold air damming and cloud cover. Max and
hourly temp trends have been adjusted down slightly.
A swath of light rain over SE CT will push east by mid
afternoon, coincident with an elevated warm front and
corresponding zone of positive theta-e advection. The threat
for icing has ended.
Some spotty light rain activity possible across the region this
afternoon associated with some weak vort energy...but overall
coverage and probabilities look slight under shortwave ridge
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
The closed and nearly cut off low that was over Missouri will
continue to open and weaken as the shortwave gets picked up by a
weak southern stream flow, and the wave moves into the eastern
ridge. There remains some timing difference with the movement of
the warm front and low tonight into Monday. Also, with weak
forcing unsure how much precipitation will occur. So have
lowered probabilities into the likely category, with the higher
chance west and north late tonight into Monday.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
With the wave continuing to dampen late Monday into Monday night
with weak ridging ahead of the next shortwave, there may be a
break in the precipitation. However, with the uncertainty, and
to keep continuity have continued with slight chance
probabilities Monday night.
Yet another shortwave approaches in the weak southern stream as
this wave also dampens as wave approaches the mid Atlantic.
There are timing differences and whether or not the shortwave
will phase with a digging northern stream shortwave Tuesday.
With uncertainties will keep probabilities at low chance Tuesday
into Tuesday night.
Wednesday and Thursday look to be dry with high pressure building
in. Cold air advection appears to be delayed enough to the point
where highs on Wednesday end up above normal, then near-normal for
Thursday. Friday could be completely dry as well, but perhaps some
rainfall sneaks into the western zones by the end of the day. High
temps again near normal. Global models then disagree with the track
of an area of low pressure that could bring rainfall on Saturday.
Have capped PoPs at 40% for now.
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --High pressure over the area this afternoon will weaken and move
northeast tonight as a warm front approaches. This front will
then lift slowly through during Monday morning.
Drier air making a westward push into the NYC metros should
raise ceilings into the VFR category until after sunset. Then
expect conditions to gradually lower through MVFR to IFR this
evening, and then LIFR toward daybreak. The timing for these
worsening conditions will be later farther north/east, and may
not occur until well after midnight at KSWF/KBDR/KGON.
Timing of warm frontal passage, with accompanying wind shift to
S and subsequent improvement of ceilings is uncertain. The
front is more likely to lift through later rather than sooner,
which would delay onset of forecast improvement--in that case
IFR conditions could last through the end of the TAF period,
with wind direction remaining more E-SE rather than S.
.OUTLOOK FOR 18Z MONDAY THROUGH THURSDAY...
.Monday...Gradual improvement in flight category, though MVFR
may hang on into the afternoon especially NE of the NYC metro
terminals, and IFR at KGON.
.Monday night-Tue night...IFR likely, LIFR possible with rain/low
.Wednesday...VFR. NW winds G20KT.
.Friday...Chance of rain with MVFR or lower conditions,
especially at night. E winds G20KT along the coast.
-- End Changed Discussion --
Marginal easterly SCA gusts are expected on the ocean waters
through tonight. The resultant easterly fetch will allow for
ocean seas to build to 4 to 7 ft. Winds are expected to weaken
and veer se on Monday as a warm front works into the
waters...but e/se swells will likely keep seas at SCA levels
through the evening.
Otherwise, sub-sca conditions are expected across all waters briefly
on Tuesday before gradually building through the evening in
strengthening southerly flow ahead of a low pressure approaching
from the west. Strong west-northwesterly flow with gusts to 25 kt
will develop on Wednesday as a cold front passes which will
initially allow seas to stay elevated at SCA levels before gradually
shifting east of the ocean waters. Stronger winds may persist into
Thursday before weakening by late week as high pressure briefly
builds over the area.
One quarter of an inch to one half an inch of rainfall is
possible today through Tuesday night.
No hydrologic issues are anticipated through Tuesday.
Latest surge guidance indicating that water levels should stay
safely below minor flood thresholds for tonight and Monday
Morning high tide.
As astronomical tides rise through the week...water levels may
come close to minor levels during high tides in the most
vulnerable spots on Tue/Tue Night ahead of approaching low
MARINE...Small Craft Advisory until 7 PM EDT Monday for ANZ350-353-355.