Area Forecast Discussion
Issued by NWS Binghamton, NY

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435
FXUS61 KBGM 301949
AFDBGM

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

.SYNOPSIS...
A storm system will continue to spread rain across the area this
evening 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 and
Poconos.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
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 /20Z THURSDAY THROUGH TUESDAY/...
VFR conditions expected the rest of today. The next system will
bring restrictions this evening and especially later tonight.
Cloud cover will thicken and lower with time. Rain will begin
around 00Z at KELM, KITH, and KSYR...and around 03-04Z at KRME,
KBGM and KAVP. MVFR restrictions initially will deteriorate to
fuel alternate required to IFR later tonight. Light and
variable winds today will become southeast 6-12 knots for KITH-
KBGM- KELM-KAVP; maintaining east- southeast KSYR- KRME. Will
see winds increase 15-20kt by Friday morning with IFR or
conditions below alt minimums possible especially for KRME, KITH
and KBGM. There may be a period of rain/snow mix at KRME between
06-12Z tonight...otherwise all terminals should see rain through
the period.

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
NEAR TERM...BJT
SHORT TERM...PCF
LONG TERM...PCF
AVIATION...BJT/MDP
HYDROLOGY...JAB



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