Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 272348
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
648 PM EST Mon Feb 27 2017

.SYNOPSIS...
Coastal high pressure will keep temperatures warm to start the
new work week. A strong storm system moving out of the central
United States will drag showers and thunderstorms across New
York and Pennsylvania on Wednesday. Colder air will follow for
the end of the week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
630 pm update...
Quick update and just tweaked temperatures, dewpoints, winds a
little. Otherwise, on-going forecast is in great shape.

400 pm update...
Area is situated in deep layer W/SW flow with long wave trough
setting up in the west and ridging in the east. In the low
levels, a warm advection pattern is set up over the area with
high pressure off the coast. Heading into tonight, clouds
increase as a weak wave moves through. This may touch off a few
rain showers, mainly over central NY, that could mix with a few
flakes but we don`t expect any accumulation as precip will be
light with low temperatures in the 30s.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
A trough over the central U.S. will strengthen on Tuesday, and
another disturbance will shoot out of the upper level flow and
move across our region. A very warm air mass will push into
NY/PA (+8C 925 mb), and breaks of sunshine are forecast for
Tuesday afternoon once the warm front passes.

Highs will reach well into the 50s for most areas in southerly
flow with some areas potentially even reaching the lower 60s
depending on how much sun occurs. The warmest areas will be the
lake plain and the valleys of NE PA.

Pattern becomes increasingly stormy heading into Tuesday night
and Wednesday. The next wave will bring increasing clouds with
chances of showers returning by late Tuesday into Tuesday night
with another wave likely bringing more showers later at night
toward 12z Wednesday. Forecast models indicate elevated
instability creeping in overnight with theta-e ridge and very
strong LLJ at 850 mb near 50 knots so we have added the slight
chance of thunder beginning overnight

Wednesday continues to look interesting as far as possible
severe weather potential but there is still a lot of uncertainty
in the forecast due to the early AM clouds and showers which may
limit destabilization. In terms of details, slowly amplifying
trough moving ewd across the central US early Wednesday morning
will combine with ridging aloft and strong WAA across the mid-
Atlantic region and become the focus of convective showers and
storms over NY and PA Wed midday into the afternoon and
evening. Much of ne PA and central NY will be situated within
the warm sector of a low passing through Ontario with
temperatures reaching into the 60s...possibly to near 70 again
in some spots. NAM indicates ML CAPE values topping out around a
few hundred J/kg to possibly as high as around 1000 j/kg over
NE PA with the GFS showing lower values. Again tricky forecast
as AM wave will bring showers and possible storms with the
better chance of stronger storms occurring in the afternoon as
a more organized pre-frontal area of showers and thunderstorms
may develop. Both low level and deep layer shear values will be
very impressive with models showing 0-1/0-3/0-6 km values of
35/45/70 knots. Also, 0-1 km helicity values will likely be near
300 m2/s2. The question will be instability...if enough is
realized the potential would be there for a scenario similar to
what happened Saturday but this is far from certain. The
potential hazards are damaging winds, hail and maybe a tornado
or two not out of the question. May also see the potential for
additional flash flooding as PWATs hover around 1 inch, and the
threat for quick heavy downpours develops in the convection.
Flash flood guidance is still very low for portions of s-central
NY and ne PA due to the recent snow melt and also the 1- 1.5
inches of rain this area received on Saturday. So, with
saturated soils any additional heavy rainfall will not be able
to infiltrate the ground and become runoff. This all said, will
continue to highlight hazards in the HWO and also note that SPC
maintains area in a marginal risk for severe weather Wednesday.
Should forecast confidence increase in severe weather, this
could be upgraded.

After the front moves through Wednesday night, temperatures
will drop sharply with showers/storms possibly ending as snow
showers. There will also be strong, gusty winds behind the front
on the synoptic scale due to strong pressure gradient on the
backside of departing low. Temperatures bottom out in the 20s to
low 30s Wednesday night and won`t rise much Thursday with some
lingering snow showers.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Period begins with the NE US in a deep trough and a cold NW flow
of air. Lake effect snow showers will continue into Friday
morning just to be followed by a shortwave clipper system
dropping through the Great Lakes. This will re-energerize the
lake effect with 850mb temps still around -20C.

Wave exits early Saturday allowing high pressure to build into
the area. This should a mostly sunny day as ridging builds aloft
ahead of system deepening over the northern plains. Warm front
pushes late Saturday and early Sunday developing some weak
isentropic lift. Best support for precipitation will remain
north and west of the area but some light snow is certainly
possible overnight. Still enough cold air to allow frozen
precipitation.

Later Sunday, warm air advection going again in full force with
strong ridging aloft and weak surface high pressure.This should
allow for a mainly dry day for the end of the weekend.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Mainly VFR through the TAF period. High pressure off the east
coast will slide east and allow a southerly flow of milder air
and increasing moisture later tonight and on Tuesday. Models
show a bit of light precipitation overnight, especially over the
Finger Lakes and into the Catskills as a wave moves through. It
is not expected to be heavy enough to cause widespread restrictions
and temperatures will not be low enough to support freezing or
frozen precipitation. Tuesday will feature continued VFR
conditions with cloud deck slowly lowering through the day.

OUTLOOK...

Tuesday night...Possible restrictions in light rain showers.

Wednesday...Possible restrictions in rain showers and
thunderstorms.

Thursday/Friday...Possible restrictions in snow showers.

Saturday...VFR.

&&

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

&&

$$
SYNOPSIS...PCF
NEAR TERM...DJN/PCF
SHORT TERM...PCF
LONG TERM...DGM
AVIATION...DGM



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