FXUS61 KOKX 110554
Area Forecast Discussion
National Weather Service New York NY
1254 AM EST Mon Dec 11 2017
A low pressure trough will pass through late tonight, followed by
building high pressure on Monday. Low pressure will then pass
across the Great Lakes Monday night, while an associated warm
front lifts through the waters Tuesday morning, followed by a
strong trailing cold front in the afternoon. Intensifying low
pressure will move from the New England coast into the Canadian
Maritimes from Tuesday night into Wednesday night, then slowly
loosen its grip on the area on Thursday as weak high pressure
slides across. An Alberta clipper low will pass to the south on
Thursday, then another low will develop just off the coast late
Friday into Friday night.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A shortwave and upper trough axis will approach from the west
overnight, with a low pressure trough at the surface. The best
combination of lift and moisture arrive after midnight with
isolated to scattered snow showers. A dusting is possible. Low
temps will be around 30 in NYC and the adjacent suburbs, with
20s for the rest of the area.
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
High pressure will briefly build in behind the departing trough
Monday morning, with a lingering snow shower still possible
mainly east of the city. Skies will start off partly to mostly
sunny, then higher level clouds will begin to increase in the
afternoon. High temperatures will be a few degrees below normal.
Low pressure moves across the Great Lakes Monday night. An
associated warm front approaches us with increasing chances of
precip late at night, more likely NW of the city. A digging
upper trough and the low center then approach us during Tuesday.
Associated deeper moisture and lift bring then likelihood of
precip across the most of the rest of the area during the
morning. The low passes us to the north before exiting during
the afternoon, with maybe a secondary low center moving through.
Expect precip chances to diminish in the afternoon with the
best lift and moisture exiting. A cold front then follows
shortly thereafter, so precip chances will continue through the
Warm advection ahead of the main portion of the storm will make this
a mixed precip event. Primarily rain is expected for the city,
adjacent suburbs and coastal section, although some snow can mix in
at first. Farther inland, snow or a snow/rain mix changes over to
rain by noon on Tuesday. Only perhaps the elevated sections of
western Orange County could see an all snow event. Snow
accumulations expected to be 1 or 2 inches for the northern
suburbs, with perhaps 3 inches in some spots across Orange
County. Less than an inch is expected anywhere else where snow
manages to accumulate. Highs in the 40s expected for most
spots on Tuesday, with even some 50 degree readings for
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
At the start of the period, blustery and cold weather expected from
Tuesday night into Thursday as intensifying surface low pressure
moves from the eastern New England coast up into the Maritimes. The
parent upper low/trough will be closing off and becoming negatively
tilted during this time, and a strong vort max rotating around the
upper low may help spark a few snow showers late Tue night into Wed
morning, especially out east. Blustery conditions expected as the
pressure gradient tightens up on the back side of the low, with
sustained winds 25-35 mph and gusts 45-50 mph possible Wed into Wed
night. With temps falling to the teens and lower 20s Wed night, wind
chills should fall to 0 to 5 below well inland, and to the single
digits in NYC metro and along the coast. High temps both Wed/Thu
should range from the mid 20s to lower 30s.
ECMWF has been more consistent than the GFS in the longer term
beyond Wed night and was followed for the most part. A weak Alberta
Clipper low should pass just south on Thu as an associated mid level
impulse passes just south, then another low should develop close by
late Friday as a more significant negatively-tilted upper trough
swings through, that could bring a period of light snow Fri
Upper level flow after passage of the upper trough on Friday should
become zonal, with moderating temps, rising to the upper 30s/lower
40s on Sat, and into the 40s on Sunday. A surface low passing well
to the north may manage to produce a few sprinkles/showers of snow
or rain late Sat night into Sunday in the low level warm advection
to its southeast.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A cold front will pass today.
VFR through about 8Z, then ceilings drop to around 3000 ft with
snow showers in the area early this morning. Little or no
runway accumulation, although visibility could be briefly
reduced to MVFR or lower. Ceilings improve to VFR after 15Z,
with VFR through the remainder of the TAF period.
Generally westerly winds through the TAF period. Direction will
be just south of west until the frontal passage, then will
become just north of west. Occasional gusts early this morning,
then more frequent gusts to 20 kt today. Gusts will end after
.OUTLOOK FOR 06Z TUESDAY THROUGH THURSDAY...
.Late Monday night-Tuesday...MVFR or lower possible with a wintry
mix to rain at northern terminals and rain at southern terminals.
Conditions improve to VFR Tuesday afternoon. SE-SW winds G15-25KT
.Tuesday night-Wednesday...Mainly VFR, with a chance of MVFR in snow
showers. W-NW winds G20-35KT probable.
.Wednesday night-Thursday night...VFR. W-SW winds G15-25KT possible.
.Friday...MVFR possible with snow. W-NW winds G15-20KT possible.
SCA conditions expected on the ocean waters through Monday with
winds and seas meeting criteria. Marginal SCA conditions
expected on the eastern Sound/bays. Winds and seas should fall
below criteria Monday night, then increase during Tuesday, with
SCA conds becoming likely on some of the waters.
As intensifying low pressure pulls away, gales should develop on
the ocean Tue night, with SCA conds continuing on the remaining
waters. NW gales expected on all waters Wed night into Thu with
a tight pressure gradient and strong cold air advection. SCA
conds may linger into Thu, then quiet conditions expected Thu
night into Fri, though winds and seas in westerly flow after the
passage of a weak low Fri night could flirt once again with SCA
No significant hydrologic impacts expected.
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time. See our headline news on
the web at: http:/weather.gov/nyc
The Riverhead NOAA Weather Radio Station WXM-80 (162.475 MHz)
is currently out of service. NWS technicians are working with
Verizon to restore service. An estimated time of return to
service is not currently known.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ350-
Small Craft Advisory until 6 AM EST early this morning for