Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
847 PM EST Friday Dec 26 2014
high pressure will build in through Saturday morning...then slide
east Saturday afternoon and night as a cold front approaches.
The front will enter the region on Sunday and then stall south of
Long Island...with an area of low pressure riding along the
front early in the week. Very strong high pressure over over the
northwestern states will slowly approach later in the week.
Near term /until 6 am Saturday morning/...
forecast on track. Just some minor changes made to hourly temperatures to
Crystal clear skies expected this evening...then some high clouds
over western PA and the Ohio Valley should start to stream in later
Rather light winds this evening have enabled boundary layer
decoupling with the loss of diurnal heating. Therefore radiational
cooling has been more effective thus far. Adjusted lows downward a
few degrees as ridge axis is expected to continue to move in
overnight. There are some higher winds aloft but generally above
3kft and on the land think these winds will continue to be light.
Lows forecast range from the low to middle 20s across the rural and
interior sections to the upper 30s for the immediate coastline and
Short term /6 am Saturday morning through Saturday night/...
deep upper trough over the central rockies and desert SW Four
Corners this afternoon will shear out into the upper Great Lakes and
nearby southeast Canada by Sat night...with an attendant cold front
approaching Sat night. A deep SW flow developing on Sat ahead of
the front will transport warmer air into the area. Highs on Sat
under mostly sunny skies should reach the Lower/Middle 50s...and
upper 50s are not out of the question over urban NE New Jersey.
The approaching front should bring increasing clouds Sat night...
with some sprinkles or showers late especially well north/west of
NYC as a pre-frontal trough and weak middle level shortwave enter
the area. Expect lows Sat night in the Lower/Middle 40s in NYC metropolitan
and coastal sections...and middle/upper 30s inland.
Long term /Sunday through Friday/...
overall...in the middle to upper levels...ridging flattens late this
weekend going into early next week. This leaves 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...a cold front moves across early Sunday and then
stalls well south of Long Island going into early next week with an
area of low pressure riding along the front. One big feature to
note next week is the very strong high pressure moving into the
northwest U.S with magnitude of at least 1050 mb. Likewise...a
very cold source of air will be moving into the northwest U.S.
This air mass gradually moves south and east through the week.
We start out still with warmer than normal temperatures Sunday.
The low levels are forecast to be above freezing allowing for
precipitation to be in the form of rain showers in association with the
The trend towards colder air begins Sunday night through the week
and this is from the really strong high in the northwest as it
translates south and east. The region stays in a general north
flow on the eastern side of the high...helping to advect in
colder and drier air. The wave of low pressure riding along the
front is forecast to stay well south of the region Monday...but
some models are showing some enhancement of precipitation as the waves
moves off into the Atlantic. As a result...these same models have
the local area on the southern fringe of the precipitation shield
associated with the wave.
With the aforementioned cold and dry air advection...a low level
environment will be setting up that could wet bulb and cool down
several degrees within the boundary layer. Therefore...low chance of
precipitation becoming more of a snow mix...mainly snow across the
interior Sunday night and Monday. The amounts are very light
though and generally less than two tenths of an inch with any
possible light snow accumulation being mostly across the interior.
Otherwise...precipitation really trends down later Monday and Monday
night with dry weather prevailing thereafter through the
remainder of the week. Temperatures overall a colder trend. Above
normal highs Sunday...near normal Monday...and below normal
Aviation /02z Saturday through Wednesday/...
sky clear as high pressure builds in from the south through Saturday.
Light west-southwest surface flow less than 10 knots through the period.
Outlook for 00z sun through Wednesday...
Sunday...VFR...localized MVFR inland. Chance -shra/-shsn.
increasing west flow could bring ocean seas close to Small Craft Advisory criteria
late tonight. SW flow ahead of the approaching cold front could
also bring ocean seas east of Moriches Inlet close to Small Craft Advisory criteria
late Sat night into early Sunday. Small Craft Advisory conds are also possible
during middle week.
no significant precipitation expected at this time.