Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Binghamton New York
323 am EST Thursday Dec 5 2013
even milder air will spread across the region tonight and Thursday
with some occasional light rain or drizzle. A cold front will
drift into the region Thursday night and lingering in the area through
Friday. A transition from rain to a wintry mix is expected on
Friday...followed by colder air and lake snows for the weekend.
Near term /until 6 PM this evening/...
920 PM update...
pulled back on the probability of precipitation this evening and accelerated the fog
formation, as there has been more clearing than expected and the
radar picture remains quiet. Trended below pop guidance, pushing
chance for showers out to early Thursday morning.
The increased clearing allowed temperatures to drop faster than expected
too, especially in the sheltered valleys east of I-81. Lowered
mins and did not forecast temperatures to begin rising until between 7z
3 PM update...
mostly tranquil weather is expected into the first part of tonight
ahead of a weak midlvl wave now pushing through the upper Midwest
and western gtlks. This feature is prognosticated to move off to our
north...but should induce some weak isentropic lift over the
region later this evening which warrants a chance for some light
rain or drizzle. A non-diurnal temperature trend is also expected
in this warm advective regime with lows occurring the during the
first half of this evening and rising through daybreak.
Short term /6 PM this evening through Saturday night/...
much of this time period will be noted for clouds and damp
conditions through Friday...before a cold front pushes far enough
south to bring in a deeper layer of cold air and lake effect snows
on Saturday. Models are generally in fair agreement on the big
picture evolution of weather systems...and they get US solidly
into the warm sector tomorrow before drifting that front into the
area by Thursday night. Here is where the challenge begins as the
front becomes parallel to the steering flow aloft and stalls over
the region with multiple midlvl waves expected to move northeast
along the boundary through Friday night. Cold air will bleed south
in the lowest levels of the atmosphere with the freezing line
bisecting central New York...and meandering slightly with the passage
of each wave. The GFS is most progressive with moving the front
south...and appears to be an outlier at this point with NAM and
European model (ecmwf) in better agreement. Experience says we should lean with
the more northerly solutions and allow the inclement weather to
linger longer. Generally...we will have varying times of precipiation
through Friday night...and our grid forecasts attempt to catch the
Ebb and flow of increasing/decreasing probability of precipitation. The mixed precipitation
transition looks to occur with the last impulse later Friday and
Friday evening. BUFKIT soundings suggest mainly a rain to snow
evolution...with a narrow ribbon of time where sleet and possibly
freezing rain could mix in. The profiles also suggest that elevation
will play a big role in any icing setup as the cold wedge is seen
aloft with temperatures above freezing in the valleys. The variability of
this scenario is too great to paint the details at this time...so
have illustrated the movement of the dominant rain/snow precipitation
with chances of the wintry mix thrown in.
Temperatures very mild tomorrow...followed by cooling Friday and
seasonably cold on Saturday. High pressure builds in from the west
on Saturday with northwest flow along a 280-290 trajectory
suggesting lake bands. The synoptic moisture dries out consierably
so at this time not looking at a major event.
Long term /Sunday through Wednesday/...
Sunday will start out dry with surface high pressure over northern New York state/New
England. Late in the day light snow may begin spreading across the
region from south to north as low pressure moves into the Tennessee Valley.
Sunday night into Monday, primarily low will lift north into the
lower lakes staying west of central New York while a secondary low,
although weaker, develops off the New Jersey coast. Since the
stronger system will lift to our west much warmer air will be
brought into the middle levels bringing the area a wintry mix Sunday
night with a transition to rain showers by Monday morning as surface
temperatures warm fairly rapidly.
Trailing cold front will cross area later Monday with strong cold air advection
following the boundary. Remainder of forecast will be cold with
upper level trough over the northeast and continued west/northwest flow. This
will set up lake effect snow showers primarily east of Lake Ontario.
Highs will range in the 20s with lows 5 to 15 degrees.
Aviation /08z Thursday through Monday/...
moist southeast flow will bring low MVFR conditions this morning
to all terminals with IFR/below alt min conditions at kith/kbgm.
By middle morning increasing southerly flow will improve ceilings to MVFR
with syr most likely low VFR. An approaching cold front will
spread rain over the terminals between 20z-22z and lower the category
into the low MVFR range. Once the winds become northwest after
fropa, around 03z across New York state terminals, widespread IFR is expected
in continued rain.
Southeast winds 5-10 knots becoming southerly by late morning
around 10 knots with a few gusts near 20 knots then shifting to
northwest this evening.
Thursday night to Friday night...IFR/MVFR in rain and mixed precipitation.
Sat/Sat night...scattered MVFR central New York....primarily syr/rme.
Sun ngt/Mon...widespread IFR/MVFR in rain and mixed precipitation.