Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 011815
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
115 PM EST Wed Mar 1 2017

.SYNOPSIS...
Today will be very warm, and a system will impact the area
bringing showers and possibly strong thunderstorms, followed by
much colder air and snow showers late tonight into Thursday.
Gusty winds can also be expected tonight through Thursday. A
passing disturbance will bring a chance for snow Friday, with
the cold will persisting through Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
940 AM Update...still looking at a very complex and poorly
organized system this afternoon and evening with the threat of
strong winds still with us. Main question remains if any
thunderstorms can develop. If they do, damaging winds a real
threat. Will continue to monitor.

In the mean time, have updated the grids to latest meso scale
forecast of rain areas, and to current and expected temps.
Previous discussion continues below.

415 AM Update...
Main concern is potential for severe weather today. Several
ingredients in the vicinity for strong to severe thunderstorms
today, yet it is also more complicated than just a strong front
sweeping through, which lends uncertainty into the details of
how this event will evolve. Strong southwest flow ahead of
approaching front is riddled with multiple waves.

Overall it appears that there will be two primary batches of
convection, with a possible additional one in between which may
be more of a glancing shot to our south.

The first one will arrive in a hurry this morning, with limited
Convective Available Potential Energy (CAPE) yet with a lot of
shear present. The associated wave is lifting up from the Ohio
Valley where clusters of thunderstorms are already occurring,
as well as an approaching linear feature now moving across Lake
Erie. There will be adequate instability aloft for high
confidence in thunderstorms carrying southwest to northeast
across the region between 8am and Noon. While these storms will
tend to be elevated in nature, lifted condensation levels will
also be fairly low due to dewpoints surging into the lower 50s,
and a strong low level jet will be present just a few thousand
feet above ground level. While overall severe threat is low with
this first batch, the strongest cells will still need to be
watched closely in case gusts are able to mix down.

As CAPE gets higher in near-record temperatures, a stronger a
wave is appearing likely to organize linear convection with a
significant damaging wind threat early this afternoon though
mainly for Central PA and southward through the Midatlantic
region. The northern edge of this potential complex could manage
to skim towards the Wyoming Valley-Poconos area, so another
thing to monitor closely. Meanwhile, further north, much of our
area may actually be rather quiet early to mid afternoon, but
given the environment any convective cell will have the
potential to turn severe. While shear is primarily
unidirectional for most of the column and thus damaging wind is
the primary threat, there is still a good amount of curvature
to the hodographs, and 0-1 km helicity is enough (a few hundred
m2/s2), to which an isolated tornado cannot be ruled out today.

Finally, the cold front itself will sweep west to east across
the area 5PM-11PM. Thunderstorm coverage will be less certain
with time, but regardless the frontal showers - whether or not
containing lightning - will likely also pose a threat for gusty
winds.

Behind the front, synoptic winds will increase with very
unstable low levels mixing down westerly gusts widespread in
the 35-45 mph range overnight into early Thursday. Parameters
meet several thresholds of local studies for wind events,
including 925-850 mb winds and strong pressure rises. For much
of Central New York, gusts could push closer to 50 mph
especially NY Thruway corridor as well as higher elevations
including the Catskills. Wind Advisory has thus been hoisted for
all of our New York zones, in coordination with surrounding NWS
offices. Lingering rain showers, mainly in Central New York,
will change over to snow as the abruptly colder air overspreads
the region.

One aspect of this system that has somewhat diminished - though
will still have to be monitored - is prospects for flash
flooding. Individual storms will move along very quickly,
limiting overall rainfall amounts. A Flood Watch is still in
effect this evening onward for Northern Oneida County, where
combined snowmelt and rain could lead to flooding along the
Black River in Boonville and perhaps other small streams.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
430 am update... The Wind Advisory will continue until 1 pm
Thursday in CNY, with steep lapse rates and good downward
momentum transfer processes at play during the first half of the
day. In the afternoon, the pressure gradient will loosen over
the region, and wind gusts should begin to decrease.

Any light lake-effect snow showers or flurries in the morning,
should weaken by afternoon.

Thursday night and Friday morning, a clipper type surface low is
expected to track well to our south across the mid-Atlantic
states. Some light snow on the northern periphery of this system
could sneak into our NEPA zones, but any accumulations should be
less than an inch.

The main story by later Friday will be the cold temperatures and
brisk winds, with readings mainly in the 20s, and apparent
temperatures in the single digits and teens.

Some lake-effect snow will likely develop over portions of CNY
Friday afternoon, owing to strong cold advection. At this early
juncture, it looks like a multi-band event (310-320
trajectories), with accumulations staying below advisory
criteria, given fairly shallow moisture, and some directional
shear.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
445 am update... On the large-scale, a deep northeastern U.S.
trough at the start of the period, should relax into early next
week. As a result, cold temperatures to start the weekend,
should moderate significantly by Monday.

Incoming high pressure should end any residual lake-effect snow
in CNY by later Saturday. Some light warm advection
precipitation (mixed light rain and snow) should develop later
Sunday into Monday, probably to a greater extent in CNY, as
compared to NEPA. A slowly approaching frontal complex from the
Midwest could bring more widespread rain showers by Tuesday.

As mentioned above, temperatures early next week will turn
milder again, with highs Monday and Tuesday in the upper 40s and
50s.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...

VFR conditions will continue this afternoon ahead of the
approaching cold front. Occasional MVFR ceilings and visibilities
are expected withe frontal passage later this afternoon and
evening. Behind the front, very strong winds will develop with
gusts over 40 kts possible, along with scattered rain showers
changing to snow showers, and again occasional MVFR ceilings and
visibilities. Exception will be at AVP where VFR conditions
will prevail behind the front. Showers will taper off later
tonight and on Thursday, however gusty winds will continue
through the end of the period.

OUTLOOK...

Friday...Possible restrictions in snow showers.

Saturday...VFR.

Sunday...Restrictions in rain and snow showers.

Monday...VFR.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...Wind Advisory from 7 PM this evening to 1 PM EST Thursday for
     NYZ009-015>018-022>025-036-037-044>046-055>057-062.
     Flood Watch from 7 PM EST this evening through Friday morning
     for NYZ009.

&&

$$
SYNOPSIS...DGM/MDP
NEAR TERM...DGM/MDP
SHORT TERM...MLJ
LONG TERM...MLJ
AVIATION...DGM



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