Area Forecast Discussion
Issued by NWS Upton, NY-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 191137
Area Forecast Discussion
National Weather Service New York NY
637 AM EST Sun Feb 19 2017
A weak cold front moves through today, followed by a stronger one
tonight. High pressure then builds in Monday before shifting
offshore on Tuesday. A warm front will approach Tuesday night
followed by a weak cold front becoming nearly stationary in our
vicinity Wednesday through Friday. A separate cold front approaches
from the west Friday through Saturday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The forecast is mostly on track so far. Updated hourly
temperatures and dewpoints to reflect the latest trends.
A shortwave to our south with a weak surface reflection will bring
some mid/high level clouds to the area this morning. Additionally, a
weak cold front or trough slowly moves through the forecast area
this morning into early afternoon with some cirrus ahead of it.
Moisture is not deep enough for any shower activity.
The tricky part of the forecast will be high temperatures. Cold air
advection during the day is on the weaker side and there is a
tendency for MOS guidance to underestimate high temps in a setup
like this in spite of progged cooling temps at the top of the mixed
layer. Mixing across the CWA will be deeper than yesterday with a W-
NW flow, and there will be a little contribution from compressional
heating due to this downsloping wind. So in spite of some cloud
cover, thinking is that most of the southern zones reach the 60s as
the offshore flow should be just strong enough to hold off or at
least temper sea breezes for a good portion of the day. Even
many spots across the northern zones should be around 60. Record
high temperatures are being forecast in some instances. See the
climate section below for the records.
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Stronger cold advection occurs tonight with a stronger cold front
moving through. Again, moisture is lacking so expect a dry passage.
For Monday, surface high pressure builds in with slow ridging aloft.
Sunny with cooler temperatures, but still above normal. MAV and NAM
MOS look too warm given temps at the top of the mixed layer, so went
with SuperBlend. Good radiational cooling conditions then set up for
late Monday night with a clear sky and light to calm winds as the
surface ridge axis shifts into the region.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
High pressure ridge drifts offshore during Tuesday. Overrunning PCPN
ahead of a warm front to the west may sneak in by late over the
westernmost zones. Otherwise, expect increasing clouds with highs
near normal. CHC PoPs for Tuesday night as a warm front/cold front
combination approach the region. Good model agreement in that the
elevated warm layer will be warm enough for primarily rain, except
for a chance of sleet across the northern zones during the evening.
With clouds increasing and warm air advection with a lack of a cold
air damming pattern, thinking is that temps remain above freezing
through the night everywhere. Have therefore removed the chance of
freezing rain across the northern zones.
With the trailing cold front departing in the morning, it looks like
a dry day for most if not all of Wednesday. The exception would be
lingering chances of rain over the eastern zones in the morning.
Cold air advection behind the front is not strong, and temperatures
are expected to be well above normal.
Will maintain previous PCPN forecast for Thursday/Thursday night at
this time, although might need to include low chance PoPs in
association with a weakening cold front. Did however bump up high
temp forecast based on temps aloft. An onshore flow will keep
coastal sections cooler, but all areas once again will have high
temps above normal.
A low pressure system then approaches late in the week with
increasing chances of rainfall.
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --A weak cold front moves across the region today. High pressure
builds in late.
Anticipate VFR conditions through the TAF period with mainly high
Light west/southwest winds of 10 kt or less early this morning will
shift to the west/northwest after 10-12Z. Northwest winds can be
expected during the afternoon, and a few gusts in the 15 to 20 kt
range are possible, especially across NYC metro terminals.
Across NYC, wind directions around 310 Magnetic are expected in the
Northwest winds diminish somewhat at night.
.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.Monday...VFR. NNW gusts near 20kt.
.Monday night-Tuesday evening...VFR.
.Tuesday night-Wednesday...MVFR possible in rain.
-- End Changed Discussion --
Low pressure will pass well north of the waters today. Winds and
seas will remain below Small Craft levels. A cold front will push
across the area waters this evening and overnight, building seas to
4 ft and providing some occasional gusts to 25 kt into Monday
morning. Will hold off on any headlines at this time, thinking that
any SCA conditions may only last for a few hours, if they occur at
all. No precipitation is expected with the frontal passage.
Following the cold frontal passage and as canadian high pressure
builds southeast across the area. The next potential chance of
marine impacts will be late in the week on Friday/Saturday as winds
strengthen ahead of an approaching low pressure system.
No hydrologic impacts are anticipated through the next 7 days.
The following are record high temperatures for today:
Central Park...66 (1997)
LaGuardia Apt...65 (1997)
JFK Apt...66 (1997)
Islip Apt...60 (1997)
Newark Apt...66 (1997)