000
FXUS61 KOKX 132119 CCA
AFDOKX
Area Forecast Discussion...CORRECTED
National Weather Service New York NY
419 PM EST Sat Jan 13 2024
.SYNOPSIS...
Deep low pressure in southeastern Canada tonight. An Arctic frontal
passage occurs on Sunday. A cold airmass will settle in for the
week. There will be chances for snow around Tuesday, and again
at the end of the week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Temperatures will continue to cool tonight with west-southwesterly
winds. Skies look to clear as drier air moves in with lows right
around freezing for most. Some interior areas will dip into the
upper-20s.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Upper low pressure will remain, and meander, across Eastern Canada
tonight through Monday morning. A rather strong shortwave rotates
into the upper low late tonight and moves across the region Sunday
with an Arctic cold front passing through. A chance of snow showers
remains possible mainly Sunday afternoon.
CAMs have been signaling the chance for snow squalls in the early
afternoon over the last three synoptic run times with the 6Z, 12Z
and 18Z models. They portray a sharp pressure and temperature
gradient with strong cold air advection behind a line of
reflectivity expected to push through. Should the squall materialize
tomorrow, it will bring brief moderate to heavy snow and gusty
winds. This will reduce visibility and may cause a hazardous
situation for anyone traveling on the road. Before the squall,
temperatures are forecasted to be in the low-40s to upper-30s for
coastal areas. This means, for most, a flash freeze looks less
likely, with strong winds associated with FROPA drying out the
roadways before they have a chance to freeze over. However, with
temperatures in the mid-30s around this time for interior areas of
southern Connecticut, dropping into the 20s after the passage of the
squall, a flash freeze and dangerous slick road conditions are
looking to be more of a concern.
Cold air filters in after the frontal passage bringing lows into the
upper-teens to lower-20s Sunday night.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
A 1050 high building into MT will ridge all the way to the Mid-
Atlantic on Mon. With a 980s low over Hudson Bay, a cold wly flow
will result locally. Wind chills based on the grids are calculated
to be in the single digits in the early mrng, then teens and 20s for
the day.
The focus then turns to snow chances, which are centered around Tue.
The cold air will be in place, but as of now, the upr trof has a bit
of a positive tilt, favoring either a light snow event or even a
complete miss out to sea. The NAM was an outlier, tucking a weak
secondary low in over LI. This soln was discarded for now as it is
too far out in time to have confidence in the soln. However, the
SREF mean, GEM, RGEM, and ECMWF are all W of GFS, so continued to go
with the blended approach of the NBM for pops, which are higher than
one might imagine if just looking at the operational GFS. The only
tweak was to limit the probs to the likely category to account for
the wide-right scenario.
For the grids, went with 3/4SM -SN, and accums around 1.5 inches.
Snowfall rates could be too low to allow max accums based on qpf, so
it could snow for several hours but not accumulate much until
pockets/bands of 1/2SM SN come thru. In general, expect a 1-3 or 2-4
inch snowfall with this event, unless the low spins up and a
stronger sys develops yielding higher amounts, or the steady pcpn
remains offshore yielding little to no accum.
Seasonably cold and dry on Thu. Stuck close to the NBM with the
typical local adjustments.
For Fri and Sat, yesterday it was the ECMWF producing a coastal low
with snowstorm potential, today it is the GFS. Both the EPS and GEFS
suggest low clustering over the Atlc in the Fri-Sat period. The EPS
is approximately 12 hours faster than the GEFS. Pops in the 40-50
percent range now, which is about a 10 percent increase from the
prev fcst, with the details highly uncertain about a week out.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Low pressure will be northeast of the region with an arctic cold
front approaching Sunday.
Mainly VFR conditions are forecast through the TAF period. Exception
will be Sunday afternoon with potential for snow showers as well as
snow squalls. These could present a brief period of IFR or lower
conditions.
Gusty winds will prevail through the TAF period. Wind direction
westerly going into tonight, becoming more SW on Sunday. Sustained
wind speeds near 20-25 kt through this evening and then 15-20 kt
late tonight into Sunday morning, before returning back to near 20-
25 kt Sunday afternoon. Gusts near 30-35 kt going into this evening,
then closer to 25-30 kt late tonight into Sunday morning. Sunday
afternoon, gusts rise back to near 35 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Peak gusts to near 40 kt possible at times, especially Sunday
afternoon.
OUTLOOK FOR 21Z SUNDAY THROUGH WEDNESDAY...
Late Sunday afternoon into Sunday night: VFR returning. W wind
gusts 35-40 kt into early evening, then decreasing to near
20-25 kt mid to late evening and thereafter.
Monday: Mainly VFR. IFR possible with chance of light snow late
Monday night.
Tuesday: IFR and snow likely. Snow tapers off at night. VFR
eventually returns.
Wednesday: VFR. W wind gusts near 20-25kt.
Thursday: VFR. WSW gusts up to near 20 kt.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Gale warning continues on all waters through tonight, and was
extended on the ocean waters through Sunday. After a lull in the
winds on the non ocean waters Sunday morning, gales may return
Sunday afternoon. With a break of several hours did not want to
extend the gales there attm. However, this break was a little longer
on the Sound, Harbor, and Bays.
In general, winds and seas blw SCA lvls Mon into Wed. There is a chc
seas linger around 5 ft on Mon on the ern ocean. Winds increase late
Wed, possibly hitting 25kt on the ocean. SCA cond are possible on
all waters, especially the ocean, Wed ngt into Thu on NW flow.
&&
.HYDROLOGY...
No hydrologic impacts expected thru Sat.
&&
.TIDES/COASTAL FLOODING...
Just a few gauges still are reporting coastal flooding, within
the South Shore Bays of Long Island in SW Suffolk County. These
sites are in a situation where water is not totally draining
out and there is residual coastal flooding. Coastal flood
warning for SW Suffolk goes until 6PM this evening.
Otherwise, high tides have passed and no further coastal
flooding is expected.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...Coastal Flood Warning until 6 PM EST this evening for NYZ080.
NJ...None.
MARINE...Gale Warning until 10 PM EST Sunday for ANZ331-332-335-338-340-
345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JMC/BR
NEAR TERM...BR
SHORT TERM...BR
LONG TERM...JMC
AVIATION...JM
MARINE...JMC/BR
HYDROLOGY...JMC/BR
TIDES/COASTAL FLOODING...JM