Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
936 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/...
no significant changes made to the forecast. Will adjust hourly
temperatures/dew points based on latest surface observation...which seem to be a bit
warmer than forecast. Will follow this trend for a few hours...and
will raise overnight lows by a degree or so.
Otherwise...weak shortwave pass across New England overnight in
zonal flow...with a few sprinkles or light rain showers overnight.
Thermal profiles support liquid precipitation. Cloud cover and warm air advection SW
flow should only allow surface temperatures to remain steady or only
slowly drop overnight. Potential for interior valleys of lower
Hudson Valley and CT to drop to around freezing in a few
spots...but overall expect temperatures to hold above freezing there.
Forecast temperatures may be a degree or so too cold. Freezing rain
threat looks to be low and sparse at worst across interior
valleys...but will be monitored.
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 as warm front passes north...with
region warm sectored in its wake.
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 miles per hour. 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 then cold air advection in its wake late.
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 answer
strong 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 tri-state.
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 /03z Sunday through Thursday/...
high pressure remains south of the region tonight. A warm front
approaches late Sunday.
VFR through the taf period. Low chance for pockets of -fzra late
tonight at kswf with MVFR ceilings. Probability too low to include in the
SW surface winds averaging 10-15 knots with gusts up to 20 knots...and
should diminish to 10 knots or less after 05z. Winds aloft...
however...will increase 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 be realized.
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 00z Monday through Thursday...
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. Marginal conds in western Long Island Sound
and New York Harbor. 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 late tonight 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 moving
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
tracks to the southeast of the waters.
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...
Location........record/year.....Forecast Monday high temperatures
* 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.
short term...precipitable water