Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
400 PM EST Sat Nov 22 2014
high pressure passes southeast of the area tonight. A warm front
approaches from the southwest Sunday. This warm front lifts to
our north Monday morning. A cold front then follows behind it
Monday night. High pressure briefly builds into the the region
Tuesday. A coastal low pressure may impact the region Wednesday
into Wednesday night. A trough of low pressure then lingers near
the area into Friday.
Near term /until 6 am Sunday morning/...
clouds marching in from the west as warm air advection is
underway...with weak shortwave expected to pass across the area
quickly in zonal flow across New England.
After analysis of NCEP models...European model (ecmwf) and mesoscale models...light
precipitation may clip a portion of the area...with the bulk of the precipitation
remaining north. Kept probability of precipitation quite low tonight as measurable quantitative precipitation forecast not
likely. However...a few sprinkles or light rain showers cannot be
As for temperatures...SW flow and cloud cover should prevent temperatures
from dropping too much overnight. However...readings near or just
below the freezing mark are possible across the interior. Do not
need much precipitation to create hazardous conditions as any rain
freezes on contact with the surface...but not enough confidence in
observing much freezing rain with borderline temperatures and sparse
coverage as mentioned to issue any advisories. This will need to
Short term /6 am Sunday morning through Sunday night/...
ridging Sunday occurs ahead of digging middle west trough. Models
remain in general agreement on overall features.
Surface high pressure departs over the western Atlantic as low pressure
organizes and deepens over the middle portion of the country. This
deepening low marches northeast toward the Great Lakes region Sunday
night...with a warm front approaching from the southwest late at
For Sunday...any morning clouds give way to partly to mostly sunny
skies. SW winds gradually turn toward the south late in the day.
Temperatures rise into the lower 50s most locales...close to a MOS blend.
Then temperatures remain steady in the evening before rising overnight
Sunday night as clouds move in and southerly winds increase.
Rain out ahead of the warm front will quickly move in from southwest
to northeast Sunday night.
Long term /Monday through Saturday/...
models in general agreement with upper flow for early week...with
phasing southern stream/northern stream and Pacific energy over the
upper Great Lakes on Monday lifting into Ontario/Quebec Monday
night/Tue. The result will be a bombing low over the Great Lakes
taking a similar path as the upper energy. Ahead of it...deep S/SW
flow...with 70-75 knots low level jet...will bring a moist airmass (pw 3-4 Standard
above normal) into the region up and over an approaching warm front.
The result should be a period of moderate to heavy rain sliding east
across the region late Sun night through Monday morning. A bit of elevated
instability and strong forcing indicate slight potential for
thunder...mainly eastern portions of tri-state. Rain should taper
off by midday Monday...with region warm sectored in wake of warm front.
Unseasonably mild temperatures...15-20 degree above seasonable...possible
across interior Monday after. A tight SW gradient and continued healthy
low level jet of 40-45 knots at 950 mb should result in windy conditions on
Monday...15 to 25 miles per hour with gusts 25 to 35. There is a low
probability for gusts of 40-45 miles per hour...particularly across higher
elevations and areas n&w of NYC Monday with any breaks of sun and
resultant deeper mixed layer. Cold front pushes through Monday
night...with some accompanying light shower activity possible...and
cold air advection in its wake.
Tranquil and near seasonable temperatures on Tuesday as high pressure builds
Then potential increasing for a coastal storm impacting the region
Wednesday/Wednesday night...but uncertainty on exact track of this system. The
driver for this system appear to be phasing northern stream and Pacific
energy diving down the back side of deep central US troughing early
this week...with the energy pivoting up the coast midweek as it
phases with yet another piece of northern stream shortwave energy.
Differences exist more so with the degree of this second
interaction...affecting how negatively tilted the trough becomes.
The result is some timing...but mainly track differences with how
close to the coast low pressure developing in the Gulf tracks to
the region Wednesday night. For now have played a middle of the Road track
between operational and ensemble means...which would track low
pressure near the 40/70 latitude/Lon benchmark Wednesday night. This would
bring potential for a rain/snow coast...snow interior on
Wednesday...changing to all snow Wednesday night for most if not all of the
region as the low deepens and track north. Too much uncertainty to
talk about snow amounts and location...but at this point a low
potential exists for several inches of snow for a portion of the
Thereafter...models are still divergent over what happens behind the
storm...but it appears most likely that there could be some
unsettled weather in its wake either due to a lingering trough
behind the low...or another weak storm system crossing the area late
in the week.
Aviation /20z Saturday through Thursday/...
hi pressure remains S of the region tonight. A warm front approaches late
Mainly VFR through the taf period. A little band of -ra mixed with
sleet is on track to reach kswf around 2130z. Included an hour group
for this. Otherwise...low chance of pockets of -fzra tonight at kswf with
MVFR ceilings. Probability still too low to include in the tafs.
Gusty SW winds diminish this evening. Winds aloft increase however to
45-50kt at 3k feet...so included low level wind shear in the tafs. If the winds mix
down...gusts to around 20kt can be expected tonight and low level wind shear will not
Lighter south-southwest flow sun. The guidance hints at possible sea breeze
component at khpn to kgon with Li sound temperatures in the 40s. This
would back winds to around 170 true after 17z.
Outlook for 18z sun through Thursday...
sun...VFR with generally south-southwest flow.
Sun ngt-Mon...warm front passes. IFR or lower in rain and fog. Low level wind shear with
50kt at 800 feet. Surface gusts over 25kt possible.
Monday night...becoming VFR with cold front.
Tuesday...VFR with west winds 20-30kt.
Wednesday...potential for low pressure to track off the coast and impact
the region. Threat for snow accums west of the low center.
SW winds will remain fairly strong into this evening and overnight
as high pressure passes well to the south and east tonight. Small
Craft Advisory remains up...but will keep western Long Island Sound
and New York Harbor out for now. A few gale gusts are possible over
the ocean waters and eastern Li sound. However...these gale force
winds are expected to be brief...so will not upgrade to gale
warnings at this time.
Winds diminish overnight and through the day Sunday as the pressure
gradient relaxes somewhat. However...winds turn to the south and
increase once again Sunday night. In fact...gale force winds are
quite possible late at night over the ocean waters...with Small Craft Advisory
criteria elsewhere. Will issue a gale watch beginning late at night
for the ocean waters.
Rough ocean seas will subside Sunday before building yet again late
Winds pick up again Sunday night into Monday as a strong low moves
through the Great Lakes region. A strong low level jet shifting
through late at night through Monday bringing the threat of gales.
Better overall chances would be on the ocean waters...but this could
expand to the other zones. Gale watch for ocean waters through Monday.
Small Craft Advisory conditions otherwise prevail Monday night through Tuesday
evening...followed by a relatively brief period of sub-Small Craft Advisory
conditions later Tuesday night through Wednesday morning. Small Craft Advisory conditions
then become more probable later Wednesday through Thursday as a coastal storm
approaches from the south.
rain moves in Sunday night with a quick half an inch to an inch
possible by the morning commute Monday. Total rainfall with this
event from Sunday night through Monday will be around an inch.
Any moderate to briefly heavy rainfall may result in urban/poor drainage
A low potential for 1/2 to 1 inch of precipitation exists Wednesday into
record high temperatures for Monday 24 November...
* Also occurred in previous years
Marine...Small Craft Advisory until 6 am EST Sunday for anz330-340-345-
Gale watch from late Sunday night through Monday afternoon for
Small Craft Advisory until noon EST Sunday for anz350-353.
near term...precipitable water
short term...precipitable water