Area Forecast Discussion
Issued by NWS Binghamton, NY

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000
FXUS61 KBGM 211959
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
259 PM EST Tue Feb 21 2017

.SYNOPSIS...
A weakening front will bring scattered light rain showers or patchy
drizzle tonight into Wednesday morning. That frontal boundary
will fluctuate in our vicinity to cause occasional small chances
of showers Thursday through Friday, with well above normal
temperatures. However, showers will become most likely into
Saturday as a moist system moves through the region.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
3 PM Update...
A wave will pass tonight, to advect in a warm airmass of Pacific
origin for Wednesday onward.

A well-marked upper wave has reached Ontario and Lake Erie with
showers. This is part of the remnants of what was a strong system
that crashed the West Coast a couple days ago. It will continue
to further weaken while carrying into our region overnight. That
being said, latest model trend is for a small jet max to run up
along it later tonight, with right entrance region of that jet
allowing for a brief enhancement of showers along the Twin Tiers.
Jet support will then wane with time, but clouds and at least a
small chance for additional showers will linger Wednesday.

There will be little if any surface reflection of this wave,
however, with winds generally remaining out of a southerly to
southwesterly direction. Aloft, remains of wave will effectively
become a warm front which will edge northeastward during the day
accompanied by a slight chance of showers on an otherwise dry day
with clouds gradually developing some holes. Warm air mass will
thus have no problem advecting over the region, surging
temperatures a good 8-12 degrees higher for maximums Wednesday;
mainly in the 50s and a few spots even getting near 60 especially
lower elevations of Central Twin Tiers, Finger Lakes NY, and
Wyoming Valley PA.

Very mild conditions will persist Wednesday night with
temperatures holding up in mid 40s-lower 50s much of the night,
thanks in part to dewpoints staying in upper 30s-mid 40s. So where
any snowpack remains, melting will continue.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
The main story for this period will be unseasonably mild
temperatures as an upper level ridge dominates the east with a
trough in the west. For Thursday, low pressure will move N/E
through Ontario with the area in a SW flow. 850 mb level
temperatures will exceed 6 C with 925 temps reaching 11+ C over NE
PA into the southern tier. As result, highs will reach the upper
50s to low 60s. There will be considerable cloud cover with the
chance of a few isolated to scattered showers as a weak boundary
pushes south into the area however this will not be significant.
Thursday night into early Friday, the boundary will lift north as
a warm front bringing a continuing chance for some showers, mainly
over the lake plain, as a large area of low pressure moves north
into the Midwest. Lows will be very mild...generally in the 40s
except some 30s in Oneida County. By Friday afternoon, with the
warm front north of the area, temperatures will be at least as
warm as Thursday with low to possibly even mid 60s possible in the
Lake Plain.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Early in the period, a large area of low pressure will track north
and east through the Great Lakes into into Ontario. This will
result in the area being on the warm side of the system. Friday
night will be extremely mild for this time of year with a
southerly flow as the low tracks north. Lows will be in the low to
mid 50s. A few showers will be possible but otherwise conditions
will be mainly dry as the cold front will still be well to the
west.

For Saturday, a strong cold front will move across the area west
to east Saturday bringing showers with even the slight chance of
a few thunderstorms as the airmass ahead of the front will
unusually warm/moist for this time of year due to a very strong
southerly flow. PWATs will also be very high, around 1 inch, so
the showers have the potential of being heavy. The good news is
that the front looks to be progressive and will clear the area
Saturday night so we are not expecting widespread significant
flooding. This is further discussed below in the hydro section.

By Sunday, the area will be in a much colder, near seasonal
airmass with some lake effect snow showers. Beyond this time the
next disturbance could bring some rain/snow showers Monday with
another warming trend to follow heading into the middle of next
week as indications at this point are for a low to track to our
west into the Great Lakes once again. This would result in snow or
a wintry mix changing to rain.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
VFR conditions will persist this afternoon into evening. A
weakening upper wave will bring light rain showers, mostly
without restrictions. However, ceilings should lower into at least
high end MVFR behind the wave later tonight into Wednesday
morning, with patchy drizzle also possible, due to moisture
trapped under inversion. Model guidance appears a bit too
pessimistic with ceilings, considering continued light southeast
to south-southwest wind behind the wave, though KBGM will likely
manage to reach fuel alternate required levels for a time. Winds
generally will be southeast to south 7-12 knots this afternoon,
diminishing to 3-6 knots tonight through Wednesday morning while
veering slightly.

OUTLOOK...

Wednesday afternoon through Thursday night...Mainly VFR except
possible spotty rain showers/brief restrictions Thursday onward.

Friday through Saturday...Restrictions from rainy frontal system.

Sunday...Possible restrictions from lake effect snow KSYR-KRME.

&&

.HYDROLOGY...
1054 AM...We introduced a potential flood hazard for the upcoming
weekend into our Hazardous Weather Outlook this morning.

A significant mild spell, with temperatures in the 50s and 60s,
is likely from Thursday through Saturday. In addition to the
thermal warmth, dewpoint temperatures are also forecast to rise
well into the 40s from Friday through Saturday, including at
night. The low pressure system bringing this surge of warm, moist
air will pass to our northwest and there could be a period of
moderate winds in tandem with the rising dewpoints. As we have
noted in previous events, wind and dewpoint are the main factors
driving rapid snow melt conditions during the late winter and
spring months. The good news is that there is not a lot of liquid
equivalent in our snow pack, although some of the North Branch
Susquehanna and Upper Delaware headwater basins, with higher
terrain, are averaging 1-2 inches of liquid. If the above
parameters come together, all the snow should be gone by Saturday
morning with runoff underway. More good news is that the storm
system looks progressive, so I`m not too sold on rainfall
exceeding a widespread inch in this situation, but there`s ample
time for the track and tendencies of this system to change over
the next several days.

Bottom line is that there are several factors pointing toward at
least significant rises on area rivers and streams, with a
potential minor flood event in the headwater tributaries and upper
reaches of the main stem Susquehanna river this coming weekend.
The branches of the Delaware could also see some minor flood flows
above the reservoirs as snow comes out of the Catskills. Although
our confidence in a flood event is fairly low at this time, the
potential for flooding should be duly noted for any early planning
needs.

&&

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

&&

$$
SYNOPSIS...MDP
NEAR TERM...MDP
SHORT TERM...PCF
LONG TERM...PCF
AVIATION...MDP
HYDROLOGY...JAB



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