Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
147 PM EST Sat Dec 27 2014
high pressure will slide off the middle Atlantic coast through
tonight as a cold front approaches from the west. The front will
move across on Sunday...and then stall off the southern middle
Atlantic coast...with weak low pressure riding along the front
early in the week. Strong high pressure over the northwestern
states will slowly approach later in the week.
Near term /until 6 PM this evening/...
patch of low clouds moving into the lower Hudson Valley may bring
a brief mostly cloudy period to Orange/Putnam counties...but downslope
west flow should thin this out somewhat. Sunny skies elsewhere should
continue this afternoon. Bumped high temperatures up slightly per
latest temperature trend. Sea breezes should put an end to warming
however along south facing coastlines. High temperatures in the upper 50s
now expected in urban NE New Jersey...with middle 50s in most places away
from the coast...and lower 50s for south facing shorelines and the
higher interior elevations.
For tonight...expect increasing clouds with the approaching
frontal system...with chance of showers late tonight most places
and likely pop well north/west of NYC. Lows tonight should range
from the middle 40s in Midtown NYC...to the middle/upper 30s across eastern
Long Island and well inland.
Short term /6 PM this evening through Monday night/...
cold front should be accompanied/followed by some light rain as it
moves through in the daytime Sunday. Shot of positive Theta-E
advection ahead of the lagging 800 mb cold front...and lift via
passing middle level shortwaves and upper divergence with an
anticyclonic jet streak to the north should result in a period of rain
for most places...especially NYC metropolitan and Long Island Sunday
afternoon as these ingredients come together. GFS/NAM MOS blend
accepted for highs...generally within a couple degree either side of
Any lingering light rain mainly for NYC metropolitan and Long Island
early Sunday evening should end by late evening as the 800 mb cold
front passes to the southeast...but skies may not clear very much...even
north/west as another middle level shortwave and the right rear
quadrant of the upper jet swing across. Cold air advection on northwest-north flow
especially late at night should lower temperatures to the 30s...possibly
just below freezing in the interior valleys.
Long term /Tuesday through Friday/...
overall...in the middle to upper levels...a zonal flow through
midweek and then a trend toward more of a trough across the
northeast towards the end of the week.
At the surface...one big feature to note is the very strong high
moving into the northern plains on Monday with a magnitude of at least
1050 mb. This will translate southeastward and it associated very cold air
mass should modify somewhat by the time it gets across the lower
48...however winter-like temperatures will return this week as
shortwaves originating from western Canada help transport some of
this air mass into the area.
Overnight GFS...gefs and sref ens members were indicating that
portions of NYC and Long Island could be brushed by some light
precipitation...which would fall as snow...late Monday night into Tuesday as
another wave passes to the S. Have added schc probability of precipitation to account for
this. Dry weather prevails thereafter through the remainder of the
week. Temperatures will be below normal.
Aviation /18z Saturday through Thursday/...
high pressure builds in from the south today with VFR conditions.
Light winds under 10 knots will continue backing to S/SW this afternoon
Scattered-broken high clouds this afternoon...lowering tonight as a cold
front approaches from the west. MVFR ceilings in -shra likely towards
daybreak Sunday at kswf. Low probability of MVFR ceilings over city
terminals as -shra move east Sunday morning.
Outlook for 18z sun through Thursday...
Sunday afternoon...MVFR possible in -shra.
SW flow will increase tonight to 15-20 knots with gusts up to 25 knots.
This plus incoming swells of 2-3 feet should build combined ocean
seas to 5 feet east on the ocean east of Moriches Inlet...so Small Craft Advisory has been
issued there from 4-10 am Sunday. Could see an occasional 25-knots gust
farther west on the ocean near daybreak...but duration will be
short so Small Craft Advisory was not issued elsewhere.
The next chance of marginal Small Craft Advisory conds will be Tuesday-Tuesday night as
low pressure passes to the south.
quantitative precipitation forecast with the frontal passage on Sunday should range from 1-2
tenths of an inch. No significant precipitation expected through
Marine...Small Craft Advisory from 4 am to 10 am EST Sunday for anz350.