Area Forecast Discussion
Issued by NWS Binghamton, NY

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039
FXUS61 KBGM 310001
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
801 PM EDT Thu Mar 30 2017

.SYNOPSIS...
A storm system will continue to spread rain across the area
tonight through Saturday. Localized flooding issues may arise
from periods of heavy rain. For some areas east of Interstate
81, there will be a wintry mix of snow, sleet, and freezing
rain. Light snow and ice accumulations will be possible at
higher elevations from the Tug Hill through the Catskills to the
Poconos.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
730 pm update...
Rain has moved into the area from the west. This has dropped
temperatures into the low and mid 30s changing rain to snow and
sleet. Some accumulation occurred in Steuben county. Further
east some modification as temperatures stayed warmer and
precipitation lightened. Snow moving into the northeast now but
no accumulation and temperatures slightly warmer. This mix will
end this evening before colder air mixes down across the
northeast. Some adjustment made. The Finger Lakes into the
Mohawk Valley will be where to watch tonight with the heaviest
precipitation.

330 pm update...
Main concerns in the near term forecast remain centered around
the  incoming storm system expected to produce a wintry mix of
rain, snow, sleet and freezing rain in the higher terrain east
of Interstate 81 in NY and PA tonight through Friday
Night...with generally rain for areas along and west of I-81.
There remains a concern for localized urban/small stream
flooding issues... especially across the Finger Lakes east into
portions of the wrn Mohawk Valley...and also potential minor
river flooding through the Susquehanna River Basin late Friday
through early Sunday.

A Flood Watch has been issued for portions of central NY and ne
PA,  from Friday morning through Sunday morning. See the latest
Hydro discussion below for details.

A Winter Weather Advisory has also been issued for areas of
central  NY and ne PA...including high elevations of Oneida
county, the wrn Catskills and the Poconos from 4am Friday
through 8am Saturday morning.

A very complex storm system will unfold tonight and continue
through  the day Friday into Friday night...with the biggest
challenge being the thermal profiles and the resultant
precipitation type that develops. Strong low pressure system
currently near St. Louis this afternoon will track ewd into the
Ohio Valley tonight with a strong push of warm, moist air aloft
ahead of the system nwd through Mid- Atlantic and into PA and
NY. The northward extent and magnitude of the warm air is in
fairly good agreement among the model guidance, but the depth
and magnitude of the cold, near- sfc layer is what will be the
main factor in determining the difference between rain, freezing
rain and/or sleet and the resulting ice accumulation.

Much of the precipitation will be focused along and north of
the warm front which will lift into wrn PA/NY tonight and is
expected to set up along or just north of the PA/NY border on
Friday. Strong layer lifting along the front will allow the
heaviest rain to fall across the Finger Lakes ewd to around
Syracuse tonight and Friday morning. May see a half to 3/4 of an
inch in this area through Fri morning. As this system enters
from the west, high pressure to the ne will back its way in from
the east along with a wedge of cold air near the surface. The
combination of the warm air advection aloft from the south and
the cold air near the surface will create favorable vertical
profiles for freezing rain and/or sleet. There may be enough
initial cold air aloft across the highest elevation areas of
Oneida county and the Catskills to produce a quick 1-3 inches of
snow/sleet...but the majority of the precip will initially fall
as rain and then change to and mix with freezing rain and/or
sleet closer to Friday morning sunrise.

The low levels will warm slightly through the day Friday and
allow  most lower elevation areas to change to rain for at
least a brief period of time. However...most locations above
1200-1500 ft in the Poconos and Catskills will likely stay cold
enough for freezing rain and/or sleet. The heavy rain is
expected to become focused over ne PA Friday afternoon as the
system begins to exit to the east and stronger forcing shifts to
the e/se. The threat for additional significant rain and/or ice
will be much less Fri night and early Sat, but will not be
zero. There should be enough moisture being wrapped around the
system to allow the showers to persist through Sat morning.
Additional ice accum from freezing rain and/or sleet is
possible, along with snow accumulation once again in the
Catskills as the colder air aloft begins to move in from the
north. Surface temperatures will remain steady or cool slightly
through the night with light rain persisting mainly west of I-81
and a wintry mix to the east.

Storm total precipitation will be a challenge. Total liquid
amounts  are expected to range from 1.5 inches across the
Finger Lakes to around 1 inch along the Twin Tiers...and
possibly closer to 1 inch further to the south from Scranton
south. Total snow amounts will generally range from 1 to 4
inches across higher elevations of nrn Oneida County, far ern
Madison County, and Delaware/Sullivan Counties. Total ice
accumulations will range from trace amounts to around a quarter
of an inch in the Catskills and Poconos.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
The low will be moving away as we head into Saturday so
precipitation will be winding down west to east to just some
lighter showers. As colder air is drawn in from the north in the
low`s wake, the trend will be for lingering rain and freezing
rain over eastern zones to becoming mixed with snow and sleet
once again....especially across the higher elevations. However,
we don`t expect much, if any, accumulation since precip will
becoming much lighter. From I-81 westward, precip will mainly
just be a few lingering rain showers.

By Saturday afternoon, precipitation should be over for the most
part however cloudy skies will persist due to moist low
levels. Highs will be mainly in the upper 30s to low 40s except
mid 40s over the Valleys of NE PA.

For Saturday night, a ridge of high pressure begins to build
into the Great Lakes with the area remaining situated in a
N/NW flow as low pressure continues to pull east into the
Atlantic. Forecast model soundings still indicate a fair amount
of low level moisture in the boundary layer suggesting overcast
skies may linger through much of the night due to low stratus.
Lows should be generally in the low to mid 30s.

The moisture should finally mix out heading into Sunday bringing
at least partial sunshine as the high moves in over the area.
Highs will be generally in the upper 40s to low 50s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
An overall active pattern will continue through the long range
with a couple systems that will have to be watched.

To begin the period Sunday night, high pressure will remain in
control keeping conditions dry though clouds will begin to
increase overnight ahead of the next system. This system will
bring a chance for more rain as a system from the south may
phase with a northern stream piece of energy. Too early to be
confident on the track and evolution of this system but it will
need to be watched closely due to continuing hydro concerns from
high river flows. Following this potential system, there should
be another reprieve for the middle of next week before yet
another system may threaten the area by next Thursday.
Temperatures will be warm enough through the period for mainly
just rain with these systems as highs will be in the 50s with
lows in the 30s to around 40.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
730 PM UPDATE...

VFR conditions will fall to MVFR this evening. Rain has moved
across central NY with isolated showers at AVP. Some mixed
precipitation could cause IFR vsbys at RME/SYR. RME has the best
chance of just snow late tonight into Friday morning. Other
sites will be mostly rain especially Friday. Late tonight and
Friday morning IFR cigs and vsbys expected at all but ELM which
will be fuel alternate.

East to Southeast winds at 4 to 8 kts tonight. Friday an
increase to 10 kts with some gusts to 20 kts.

OUTLOOK...

Friday night through Saturday...Restrictions likely in
showers, especially Friday night. Snow or sleet may be mixed in
at times for KRME.

Saturday night through Monday...Primarily VFR.

Monday night and Tuesday...Good chance of rain and associated
restrictions.

&&

.HYDROLOGY...
145 PM EDT UPDATE...Hoisted the second Flood Watch this week for
the Susquehanna river basin as another low pressure system
moving in from the Southern Plains will bring additional rain
and runoff. This time, models suggest rain amounts will be
higher than earlier this week, and runoff from the rain and
continually melting snow in the headwaters has the river
simulations now exceeding flood stages by almost a foot at some
gauges. Several more points are also forecast to get at least
close enough to flood stage to be a concern. Due to the very
complicated weather situation setting up with mixed
precipitation going over to rain late tonight and Friday, the
overall confidence in the river simulations is generally low for
the specific crests...but maybe medium confidence in at least
getting the flood category correct at the usual high frequency
flood spots.

Of secondary concern will be the behavior of the Finger Lakes,
and Oswego basin streams and rivers from Syracuse to Utica as
latest QPF forecasts focus the rain axis over that region.
Generally think there may be localized water problems associated
with roadside ditches and urban storm drains if rain comes down
quickly. Also keeping an eye on the heavily regulated Finger
Lakes-Canal system.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from Friday morning through Sunday morning for
     PAZ038-039-043-047.
     Winter Weather Advisory from 4 AM Friday to 8 AM EDT Saturday
     for PAZ040-044-048-072.
NY...Flood Watch from Friday morning through Sunday morning for
     NYZ044>046-055>057.
     Winter Weather Advisory from 4 AM Friday to 8 AM EDT Saturday
     for NYZ009-036-037-045-046-057-062.

&&

$$
SYNOPSIS...BJT/TAC
NEAR TERM...BJT/TAC
SHORT TERM...PCF
LONG TERM...PCF
AVIATION...TAC
HYDROLOGY...JAB



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