Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 240552

Area Forecast Discussion
National Weather Service Binghamton NY
152 AM EDT Mon Oct 24 2016

A fast moving disturbance will bring rain showers to most of the
region overnight. The majority of the upcoming week looks chilly,
with daily highs only in the forties to lower fifties. A few light
lake effect rain or snow showers are possible over central New
York later Monday into Tuesday. Otherwise, mainly dry weather is
foreseen for the first part of the work week.


Local radars continue to show precipitation aloft increasing over
Western NY, but surface obs show to find anything steady you have
to go back to lower Michigan. These showers are ahead of an upper
level disturbance just northwest of Detroit. As this feature
tracks southeast, hi resolution models continue to support our
going forecast of a rapid increase in precip chances especially
between 02Z and 06Z over our area. The new runs have come in
slightly farther north with the precipitation bullseye but its
still roughly along the NY/PA border overnight, with another small
axis over Central NY. Overall forecast in good shape with minor
cosmetic adjustments. While a few showers may linger into early
Monday morning I did increase the gap in between this departing
rain, and lake effect rains developing later Monday afternoon. The
previous AFD is below.

Bkn cloud deck is persisting across central NY this afternoon in
an area of broad low-level convergence with some lake enhancement.
Latest high resolution models continue to show that showers may
break out in this convergence zone over Lake Ontario eastward
toward the Mohawk valley late this afternoon or early this
afternoon ahead of a short wave system tracking southeast from the
Great Lakes. The main rain associated with this feature is
forecast to track across southern NY and northern Pa later this
evening into the early morning hours on Monday. NAM/GFS/Canadian
GEM and ECMWF are in reasonably good agreement showing the axis
of heaviest precipitation, generally near or just a little over
0.25 inches, near or just south of the NY/Pa state line.
Model differences are not large enough to significantly impact
the forecast. We are going with chance pops for showers east-
southeast of Lake Ontario early this evening, then likely pops for
rain showers over much of the area late tonight through about 08z
with the best chance for rain being over northern Pa and far
southern NY.

The bulk of the precipitation associated with this wave will be
east of the area by daybreak Monday. Monday will feature a chilly
northwesterly flow with scattered light showers developing
southeast of Lake Ontario as 850 mb temperatures fall to around -2
to -4 by late in the day, resulting in a lake/850 mb temperature
differential of around -16 by 00z Tuesday. The Canadian GEM model
has some fairly healthy looking bands developing southeast of the
Lake during the afternoon Monday, while the other models appear to
be weaker and more disorganized with this precipitation through
the day Monday.


315 pm update...A chilly, cyclonic flow pattern is still expected
to prevail for much of this period, with a slow moving upper
vortex over eastern Canada, and ridging back over the Midwest.

Given some low-level moisture, 850 mb temperatures near -5C, and
deep northwest flow, some lake-effect showers are expected over
Central NY Monday night into Tuesday. Where surface temperatures
are colder (mostly the higher terrain), some of these showers
should be in the form of snow. This will not be a major event,
given shallow moisture and marginal boundary layer temperatures,
but a coating of snow seems plausible over the higher terrain,
from south/east of Syracuse towards the Catskills, later Monday
night or early Tuesday morning.

Later Tuesday night into Wednesday, lake effect mechanics should
gradually break down, as inversion heights lower and warm air
advection starts to occur. As a result, we only expect a few
lingering sprinkles or flurries later Tuesday. Many areas should
see breaks of sunshine by Wednesday.

Readings will stay chilly though, as even by Wednesday, we`re
looking at highs in the upper 30-mid 40s.


330 pm update...Overall, this period will feature progressive
flow over the CONUS, with a mean upper-level trough over the
eastern states and a mean ridge across the intermountain west.

A couple of short-waves are progged to roll across NY/PA (one on
Thursday, and then the next by later Saturday). Each should be
accompanied by a period of showers. Lingering cold air early
Thursday may result in an initial rain/snow mix, if precipitation
starts early enough.

Chilly highs in the forties late in the work week, should begin to
rebound next weekend.


A fast moving weak area of low pressure in northern Pennsylvania
will bring restrictions early this morning to the southern terminals.
At KBGM/KAVP, MVFR conditions in rain showers will continue until
08Z. Once the showers at KAVP end VFR conditions are expected for
the remainder of the TAF period. At KBGM, ceilings will remain
MVFR after the showers pass and possibly drop into the alternate
required category through 13Z. At KITH, prevailing MVFR ceilings
are expected with occasional alternate required conditions through
13Z. At KELM, MVFR conditions are expected through 13Z. After 13Z
VFR conditions will prevail at all TAF sites. A widespread strato
cumulus deck is expected with ceilings around 4k ft. Isolated
rain showers are also likely this afternoon across central New
York but not included in TAF due to limited areal coverage.

Winds shortly after sunrise increasing from the northwest at
10-15 knots with gusts around 20 knots. Winds overnight will
remain northwest at 10 knots with gusts on the hilltops.


Tuesday - Wednesday...Mainly VFR.

Thursday/Friday...MVFR possible in showers.




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