000
FXUS61 KBGM 191120
AFDBGM

AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
620 AM EST Wed Dec 19 2018

.SYNOPSIS...
High pressure will provide dry weather into Thursday. A storm
will bring rain to the area Thursday night through Friday.
Cooler weather is expected Saturday and Sunday with scattered
snow showers.

&&

.NEAR TERM /THROUGH THURSDAY/...
6 am update...
Just minor changes to sky cover and temperatures. Low clouds
have moved out to the northeast.

130 AM update...
Lake clouds still remain over the northeast counties keeping
temperatures up. There is a push to the east as low level winds
shift to the southwest. These clouds should only be in Oneida
County at sunrise, then shift northeast by 10 AM.

Mainly clear skies across the rest of the area has allowed
temperatures to fall into the teens and single digits. Have
lowered temperatures further. Despite these cold temperatures
this morning an increasing southerly flow of warm air will move
in today and last into Friday. Highs today will be in the lower
40s and upper 30s under mostly sunny skies and light winds.

Tonight lows in the 20s with light to calm winds. Clouds don`t
start to increase until late and at upper levels.

Thursday will be mild with skies becoming cloudy. Highs will be
in the low and mid 40s. Southeast and south winds increase to 10
mph. With the warm air, snow will ripen and valleys will lose
it completely by the end of the day. Rain comes into NEPA and
Sullivan County NY late in the day well ahead of the stacked low
in the southeast US.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
430 AM Update...

A strong Low pressure will develop over the deep south on
Thursday then track northward, just to our west into Friday. An
impressive surge of warm air advection will come northward into
the region, with 850mb temps approaching +10-12C Friday. Ahead
of a warm front associated with this system moisture will
overrun the front leading to widespread rain Thursday night
through a good portion of Friday. Southeast winds will increase
overnight and into Friday, between 10-25 mph, with gusts 25-40
mph...winds will be locally higher along the ridgetops, especially
in NE PA. Latest guidance, and SPC outlook indicates the chance
for t`storms across much of the forecast area beginning early
Friday morning and into the day. Temperatures surge well above
average, reaching the mid-50s to perhaps even lower 60s in some
of our valleys Friday afternoon. Dew points reach the upper 40s
(north) to mid-50s (south), and pwats are between 1-1.5
inches...well above climo for this time of year. This should
melt all of the remaining snow pack around the region. Between
1-2.5 inches of SWE remains in the highlands of Central NY and
the southern Tug Hill plateau...with less than 1 inch SWE
elsewhere. A strong low level jet around 60kts from the
southeast at 850mb (75kts along the coast) will also help to
transport significant amounts of moisture into the area.

We will have to watch for a heavy rain threat as we get closer
to the event with modeled QPF from 1.25 to 2.25 inches of rain,
highest the further east you go. This amount of rainfall could
easily lead to poor drainage, and low land ponding of water.
Streams and creeks will see significant rises, likely near
bankfull in some areas. We will need to watch the river
forecasts closely, as rises are expected to continue Friday
night and even into Saturday on the main stem rivers. Cannot
rule out some river/stream points reaching minor flood
stage...and the MMEFS continue to show this possibility. Updated
the HWO to reflect these possible hydro issues. Flood watches
may eventually be necessary. Please check back for the latest
forecast updates.

As the low moves north of the region Friday night strong cold
air advection develops, with 850mb temps reaching -5 to -8C by
daybreak Saturday. Surface temperatures are slower to fall,
reaching the mid-30s to lower 40s by midnight, then eventually
30-38 degrees by daybreak. The colder air will be northwest and
higher elevation, with the slowest cooling in the Wyoming/Delaware
valleys of NE PA. The rain does eventually mix with snow from
NW to SE overnight. Staying all rain from Monticello to
Honesdale, Scranton and Wilkes-Barre. Any snow amounts will be
confined to the higher elevations and mainly under 1 inch.

Saturday: Upper level trough is overhead, with a moist NW, cold
air advection pattern. This will lead to likely PoPs for snow
shower north, fading to chance and slight chance over the far
SE. Up to an inch of snow is possible in portions of CNY. It
will be breezy to windy, with NW winds 15-25, gust to 35 mph.
Much colder, with nearly steady temperatures in the 30s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
430 AM Update...

Saturday night: Scattered snow showers and flurries continue on
a westerly flow (270-290)...mainly affecting north central NY.
Otherwise it will be partly to mostly cloudy and seasonably cold
with lows in the 20s. WNW winds gradually decrease through the
night, 8-15 mph.

Sunday: Cold westerly flow pattern continues with just a slight
chance to low end chance for a few snow showers across the NW
portion of our CWA. West winds 6-12 mph, with highs in the lower
to mid-30s.

Sunday night and Monday: Latest model guidance is in fairly
good agreement that a shortwave trough and associated weak low
pressure center will quickly move through the Ohio Valley and
over our region during this timeframe. Weak warm air advection
should be enough to produce a period of light snow over the
area. Bumped PoPs up solidly into the chance range at this
point, and changed weather wording to stratiform light snow. If
current guidance is correct, we could see a widespread 0.5 to 2
inch type of snowfall. Seasonable temperatures with lows in the
mid to upper 20s and high in the 30s.

Monday night and Tuesday: A fairly zonal to weak NW flow pattern
continues. Some guidance suggests lake effect snow showers
continuing. Therefore left chance PoPs in the forecast up toward
Syracuse, Cazenovia, Cooperstown, Utica and Rome...fading to
slight chance or less further south. Subtle hints that the next
weak wave/clipper passes nearby in the Tuesday timeframe...however
this could change being 6-7 days out. For now, have slight
chance to low end chance PoPs for snow showers in the forecast.
Little change in temperatures.

Wednesday: Early indications are for upper level ridging and a
surface high to begin building over the area with a gradual
warming trend. A storm system begins to take shape well to our
west over the Central Plains.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
630 am update...

Only high clouds and VFR which will continue through tonight.

Light and variable to calm winds early this morning. During the
day today south winds at 5 kts. This evening, southeast to
south winds at 5 kts or less.

Outlook...

Thursday...VFR.

Thursday night through Friday night...Large system impacts area
with restrictions and rain.

Saturday/Sunday...A lingering chance of mixed rain-snow showers
and associated restrictions.

&&

.HYDROLOGY...
A powerful low pressure system with unusually high levels of
moisture and warm temperatures will move through Thursday
evening through Friday night. The heaviest period of rain is
expected Thursday night, but occasional heavier showers and
perhaps even a few thunderstorms will linger into Friday. The
rain tapers to showers Friday night, and as cooler temperatures
move in mixes with snow. Current forecasts indicate anywhere
from 1 to 1.75 inches of rain are expected Thursday night
through Friday night, except locally 1.75 to 2.25 inches from
Scranton to Monticello east. 1 to 2.5 inches of SWE remain in
the snowpack over the higher elevations of central NY, and this
is fully expected to melt as temperatures rise well into the 50s
Friday, and dewpoints also rise into the lower 50s. The
combination of this moderate to heavy rainfall and snow melt
will cause significant rises on area rivers and streams. Poor
drainage and low lying areas could see standing water. Streams
and rivers look to reach bankfull, with several points also
possible reaching minor flood stage. The latest MMEFS indicate
this possibility, especially for the headwater points. The
rivers may not crest until Saturday, as the runoff gradually
decreases and things freeze back up Saturday night.

&&

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

&&

$$
SYNOPSIS...TAC
NEAR TERM...TAC
SHORT TERM...MJM
LONG TERM...MJM
AVIATION...TAC
HYDROLOGY...

NWS BGM Office Area Forecast Discussion