Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 271502

Area Forecast Discussion
National Weather Service Binghamton NY
1102 AM EDT Sat May 27 2017

A system moving by to the south may brush northeast Pennsylvania
with a few showers today. Otherwise mostly dry weather is
expected until the next system brings showers and the chance of
thunderstorms late Sunday into Monday. A generally unsettled
pattern will persist through much of next week.


1100 AM EDT Update...
A weak shortwave aloft is sliding across the region this
morning which can be well noted on water vapor satellite this
morning. NW flow is also taking place and advecting dry air at
mid and upper lvls across central NY. The mentioned wave will
quickly swing across the region and anti- cyclonic flow aloft
will shift over the area this evening and the winds within the
lower profile of the atmosphere will become light and variable.

This shortwave aloft is currently over central PA/NY and is
generating a few light rain showers over central PA. It appears
that these showers will completely miss our area. Over central
NY, are a few areas of drizzle as a strong subsidence
inversion dominates. While the inversion will hold throughout
the day, the drier air will eventually win and dry our the lower
layers of the atmos enough by early afternoon that the drizzle
will dissipate.

Cloud coverage will slowly break apart late afternoon/evening,
thus sfc temps will rise into the uppr 60s to low 70s this
afternoon. Tonight as cloud coverage breaks sfc temps will fall
into the uppr 40s to low 50s. Fog development also looks
promising tonight.

Previous forecast discussion...
300 AM EDT...
For Saturday night, weak ridging will briefly move over the
area resulting in skies becoming mainly clear with light winds.
This will result in a good chance for some valley fog to develop
by morning as temps cool to dew points. Lows will be
cool...mostly upper 40s to low 50s.

For Sunday, early morning valley fog quickly burns off with some
sunshine before clouds thicken up ahead of the next system
approaching from the west. Most of the day should be dry but we
do introduce a chance of showers and the risk of thunder to the
western southern tier by late day. The warm advection pattern
developing ahead of this system will result in 850 mb temps
rising to around 12 C which will result in highs generally
reaching the low to mid 70s.


330 am update...
Main concern in the short term is focused around the passage of a
cold front and the increased potential for showers and a few
isolated weak storms...mainly Sunday night and Monday morning. Will
also see a second front move through Tuesday afternoon with more
showers and isolated storms.

Upper level ridging will be shifting to e/ne Sunday evening as the
next upper low drops in from central Canada across the ern Great
Lakes Sunday night and Monday morning. A lead short wave ahead of
the main cutoff low will have a surface front associated with it and
a narrow corridor of deep layer moisture and strong dynamics.
Elevated instability should be sufficient for a few weak storms
through Monday morning. The main threats will be cloud to ground
lightning, brief heavy rain and gusty winds. The heaviest
precip is expected to move in from the west/sw around midnight
along the Twin Tiers and the Finger lakes...and track to the
e/ne through the morning hours fairly quickly. The deep layer
moisture is expected to move to the east ahead of the front with
a wedge of drier air filtering in on the back side. There will
likely be enough broad large scale lifting going on to keep a
relative abundance of clouds around through the rest of Memorial
Day, and possibly a few isolated rain showers, but the threat
for continuous rain through the holiday afternoon/evening is
fairly low. A few breaks in the clouds cannot be ruled out, but
given the pattern, not very optimistic. Morning rain is expected
to amount to a quarter to half inch at most.

Weak ridging and a drier air mass Monday night/Tuesday morning will
likely keep weather conditions quiet. Can`t rule out a stray
sprinkle or periods of drizzle though. A secondary front will slide
in from the west late Tuesday morning and increase the potential for
a few rain showers through noon. This front will interact with a
gradually destabilizing boundary layer Tue afternoon...BL CAPE
around 200-500 J/kg, steep lapse produce a better chance
of scattered showers and storms. Thunderstorms should remain weak.
May see another tenth to quarter of an inch.

Temperatures will remain steady and nearly seasonal with highs in
the 60s and 70s...and lows in the 50s.


330 am update...
The parent upper low across Canada will rotate ewd Tuesday night
through Friday and bring a slug of cooler air south across NY and PA
late this week...along with periods of showers and storms. The upper
low will have a series of embedded waves rotate around it as it
tracks through Quebec...which will likely trigger the showers. The
threat for storms is tough to nail down at this point. If an
embedded wave swings through central NY/ne PA during peak heating of
the afternoon, the convective potential will be enhanced with
steeper lapse rates and more instability. The one limiting factor
will be the presence of cooler air within the boundary layer and the
lack of any significant deep layer moisture. So, will continue with
chance pops during the afternoon/evening hours Wednesday and
Thursday and lower slight chc pops during the morning and over night

The upper low begins to lift out of the area Thursday night and
most of the area starts to become under the influence of upper level
ridging and weak warm air advection. Temperatures will slowly warm
back into the lower/mid 70s as the work week comes to an end...and
the potential for rain decreases under weak high pressure.


Low stratus persists into this morning with IFR likely until 14z
for KBGM while KITH/KSYR will continue to fluctuate between
Fuel alternate MVFR and IFR until 14z. Conditions are slightly
better at KAVP and KELM where fuel alternate MVFR will persist
until mid morning with cigs lifting beyond this time. All sites
are expected to be VFR by 18z.

Skies clear tonight as a ridge briefly moves in and this will
set up favorable conditions for valley fog at KELM with IFR
likely beginning around 8z. Remaining sites stay VFR.

Surface winds will be light (5 kt or less) throughout the


Sunday...Mainly VFR.

Monday through Wednesday...Restrictions possible from scattered
showers and perhaps thunder.




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