Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 220436
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
1236 AM EDT Mon Apr 22 2019

.SYNOPSIS...
A slow moving low pressure system will slowly move east across
the region into Monday bringing a few showers with it. High
pressure will build into the region Tuesday with warm temperatures.
The next cold front moves through our region Tuesday evening
and night bringing a good chance for showers and a few
thunderstorms. A return to mainly dry and seasonable weather
expected mid week.

&&

.NEAR TERM /THROUGH TODAY/...

Only minor changes with temperatures and sky cover made with
the midnight update. Forecast on track in discussion below.

930 PM update...
Light spotty rain showers continue across northeast
Pennsylvania, the western Catskills and into the local
Binghamton area. Radar trends indicate a gradual dissipation
which will continue into the overnight hours in the same
general location. Just some minor POP adjustments to the near
term based on radar trends and latest model guidance.

345 PM Update...Weak upper level low still spinning across
Central PA up into NY late this afternoon. There is a weak
surface low reflection also over eastern PA, with a wind shift
boundary working its way across our CWA at this time. Skies are
mostly cloudy as steep low level lapse rates have allow for
some marginal instability and cumulus development over the
region. Weak surface convergence is initiating a band of showers
across the Poconos north into the western Catskills and leather
stocking region of central NY. A few pop up showers are also
present across southern Steuben and Bradford counties. This
shower activity is very slow moving and generally just meandering
around. Thus far rainfall amounts directly under these showers
has been light, less than a quarter inch...with little if any
outside of these two areas noted above. The shower activity
remains basically in place through the evening hours, but slowly
dissipating in coverage.

Tonight: The upper level circulation drifts off to the south
into the Mid-Atlantic, our flow turns north-northwesterly with
some upslope clouds likely developing and patchy fog late. Could
still see a few stray showers, but overall should be very light.
Cooler with lows in the 40s.

Monday: The upper level low moves slowly northeast just off the
coast. This will keep a northwest flow over our region through
the day. A period of light rain or showers will be possible
across our eastern zones, as precip rotates in from the east
around the mid/upper level circulation. Still some uncertainty
on exactly where this sets up; so held PoPs at chance (not
likely at this time). Latest guidance is indicating a low
stratus cloud deck in the morning, only very gradually lifting
and breaking up by late morning or early afternoon. The clouds
may hang on much of the day across the Susquehanna region of
central NY. With the chances for showers and clouds around, it
will keep it cooler (especially where the clouds lingering into
the afternoon). Forecasting high temperatures in the mid-50s to
low 60s across the Susquehanna region and Finger lakes of NY.
Further south, across the far southern tier of NY and NE PA,
temperatures look to reach the mid to upper 60s.

Monday night: Upper level low finally pulls east into New
England bringing any shower chances with it. Our area dries out
as an upper level ridge and surface high move overhead. Winds
go light and variable with some patchy fog possible in the
valleys. Cool with lows in the 40s again.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
For Tuesday, the day starts off under a ridge of high pressure from
the surface up to the upper troposphere. Skies should begin with
patchy high clouds ahead of the next upstream system which was
moving through the Great Lakes. There could be some lingering
patchy valley fog as well that burns off by late morning. As
the day progresses, the ridge slides east and NY / PA comes
under a deep southwesterly flow of air. The low- level winds
will accelerate during the day as a low- level cyclone and
associated cold front reach the Eastern Great Lakes late
afternoon and early evening. The low-level ageostrophic winds
will be pointing northerly and convergent as an upper level jet
streak moves to the upper Ohio Valley and Lower Lakes. Much of
NY and northeast PA will be in the left exit region of this
upper feature which leads to divergence and southerly
ageostrophic winds aloft. Hence the lower level branch of the
ageostrophic circulation is what is driving this southwesterly
flow in the low-levels. This will lead to moisture and warm
advection and low-level convergence in the presence of
divergence aloft spreading into NY and PA in the afternoon and
evening Tuesday.

Additionally, given the above dynamics, there will be strong
vertical wind shear and even some turning in the hodograph in
the 0-1 km layer. This usually is an excellent set up for
severe weather in NY and PA. But, there is a marked lack of
instability even in the NAM which usually is most aggressive
with the instability fields. NAM Surface based CAPEs are running
less than 500 J/kg. Mixed layer CAPE is also generally 100-300
J/kg. The GFS is similar with just slightly less CAPE. Model
soundings for both NAM/GFS show that it is initially very dry in
the low-levels as well. These are limiting factors for any
severe weather and if the models hold, we should see mainly rain
showers with scattered thunderstorms late Tuesday into Tuesday
night. This is consistent with SPCs Day 3 outlook of general
thunder. This still is something to watch for future shifts. It
just depends how fast we can moisten up in the low- levels
before the cold front and dynamics kick in later Tuesday and
Tuesday evening. For now, have POPs increasing from Tuesday
afternoon, peaking in the evening and then dropping off after
midnight as the front clears the region.

For Wednesday, high pressure presses eastward reaching the eastern
Lakes by the end of the day. There will be a northwest flow of
chilly air aloft across central NY and northeast PA all day with
wrap around stratocumulus which will be thickest in northern NY
down to the Catskills and thinner farther west and south. With
insolation I see this stratocumulus evolving into a cumulus
later except from the upper Mohawk valley to Western Caskills
where upsloping will counter the dry air mixing into the surface
layer. Will have higher cloud cover in these areas and less
farther west and south in the afternoon. Some linger light rain
showers are possible from the Upper Mohawk Valley to the
Catskills mainly Wednesday morning.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Rain chances wrap up Wednesday night as a ridge of high pressure
begins to build in. Dry and sunny weather is expected for
Thursday with temperatures starting in the upper 30s to low 40s
peaking generally in the 60s. Friday becomes a little more
interesting, as a surface low heading into the mid- Atlantic
while at the same time another shortwave moves through Ontario
and Quebec. This will bring in rain chances early Friday ahead
of the approaching cold front, which should finally track
through the area during the afternoon and evening. Expect
morning lows in the 40s and highs in the 60s.

A few showers may linger early Saturday with some wraparound
moisture and the exiting upper wave, but then much of the weekend is
looking dry and sunny with high pressure building over the southeast
US. As the ridge starts to slide off to the east during the day
Sunday, there are indications for some weak waves to start passing
through. A few showers cannot be ruled out, otherwise expect partly
cloudy skies. Temperatures will be cooler the rest of the extended
period and should start off in the 30s and 40s before peaking in the
50s to low 60s.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...

Celling restrictions likely developing as get closer to
sunrise. All locations should reach MVFR with the likelihood of
some fuel-alternate values around sunrise. A brief interval of
IFR can not be ruled out either. Ceilings will be slow to lift
during the morning but should lift to VFR by early afternoon.
Winds will generally be 10 knots or less.

Outlook...

Tuesday...Mainly VFR a few restrictions with some showers
possible by sunset.

Tuesday Night through Wednesday morning... Some restrictions
likely in periods of showers and a chance of thunderstorms.

Wednesday afternoon through Thursday...VFR expected.

Friday...Restrictions possible in scattered rain showers.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.

&&

$$
SYNOPSIS...MJM
NEAR TERM...MJM/MWG/RRM
SHORT TERM...DJN
LONG TERM...HLC
AVIATION...MWG


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