Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 221953
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
253 PM EST Wed Feb 22 2017

.SYNOPSIS...
A southwest flow of mild air will be over our area into the
weekend. This will bnring temperatures well above normal for
February. Weak areas of low pressure will bring a low chance of
showers from time to time before a stronger system brings
widespread rain on the weekend.

&&

.NEAR TERM /UNTIL 6 PM THURSDAY/...
A small patch of showers will affect areas near the NY/Pa border
west of I-81 through late this afternoon. Otherwise, mild air
will continue to work slowly into the area from the southwest
tonight. Dew points are still relatively low over central New York
and northeast Pa, but dew points as high as the lower 50s are not
very far away, already reaching northeast Ohio, southwest NY and
northwest Pennsylvania. This moist air will be pulled into our
area ahead of a weak cold front on Thursday. Increasingly moist
air over cold ground will result in patchy fog development late
tonight along with areas of low clouds. Meanwhile an area of low
and mid- level clouds will be advecting toward the area from the
west- southwest. Putting this all together it looks like a fairly
cloudy and mild night setting up across the area tonight wtih lows
ranging from the upper 30s east of I-81 to the upper 40s over the
central Finger Lakes.

A weak cold front will limp southeast toward the area on Thursday
passing southeast of the area late Thursday / Thursday evening.
Ahead of the front temperatures will soar into the lower to mid
60s. Record highs tomorrow are 60 at BGM, 69 at AVP and 68 at SYR.
So at this point it looks like the record high at BGM will be in
serious jeopardy, but temps may stay just short of the records at
SYR and AVP. Scattered showers will probably develop along and
ahead of the weak cold front Thursday afternoon with the best
chance being over upstate NY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Deep southwest flow aloft will keep the easterly movement of
surface features slow through the area. Frontal boundary running
from the mid Mississippi valley to the Great Lakes will creep
eastward as upper system race northeast in the upper flow. This
will keep a risk of showers at times...but more importantly keep
mild air over the forecast area through the short term. Expect
very little change in the weather through Thursday with the upper
ridge holding firm.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Southerly flow ahead of a strong midwestern low pressure center
will pull the +15C 925mb isotherm to the NY/PA border on Friday.
With a warm front to our north and a cold front approaching from
the Ohio Valley, mainly cloudy skies will be over our forecast
area with a few showers expected. Appreciable breaks of sunshine
would allow temperatures to make a run at 70 degrees, but this
seems unlikely. Even with the cloud cover most areas will reach
the lower 60s Friday afternoon.

A strong cold front will move through NY/PA on Saturday. Heavier
showers are expected along the front, including a slight risk for
a few thunderstorms in the abnormally warm/humid airmass. PWATs
are north of 1 inch, so we will need to watch for downpours in
heavy rain showers.

Much colder air filters down from Ontario Saturday night into
Sunday, changing rain showers over to snow showers. After wintry
temperatures return on Sunday and Monday, a temporary mild spell
is forecast ahead of another approaching cyclone, beginning on
Tuesday.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
Expect VFR conditions this afternoon with sct-bkn clouds at or
above 5000 feet. A mid-level cloud deck will overspread the area
toward evening with areas of MVFR cigs developing overnight along
with patchy light fog. Conditions will improve again later
Thursday morning with VFR conditions expected at all of the TAF
sites by early afternoon. Winds will be light and variable tonight
into Thursday morning, then southwest around 10 kts by Thursday
afternoon.

OUTLOOK...

Thursday 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...
1215 PM UPDATE...
Significant warmup with increasing humidity still appears to be a
high confidence forecast as low pressure tracks to our west with a
deep southwest flow setting up. The melting of the remaining snow
pack therefore seems pretty likely. The upper reaches of the
Susquehanna and Delaware basins should lose generally 1 to 2
inches of SWE with some basins potentially higher. There may be
some limitation to a complete melting of the deepest snow cover
over N. Oneida county, but still expecting at least half of that
SWE will come out, which could easily be 3 inches.

This water alone is likely to push gauge monitored tributaries
and headwater rivers above their posted action/caution stages.
Additional rainfall would introduce the possibility for minor
flooding of the typical Spring melt season flood prone rivers and
streams. The Meteorological Model Ensemble Forecast System does
indicate a chance for minor flooding occurring at these more
sensitive forecast points along the Chenango, Tioughnioga and W.
Branch Delaware tributaries...as well as some of the most
sensitive locations on the main stem Susquehanna.

The chance for any flooding is highly dependent on forecast
rainfall, which in our opinion, may be overdone at this time as
the current track of the surface low would suggest that the warm
frontal rainfall on Friday-Friday night should be pretty light.
The trailing cold front expected on Saturday could make up for
that as it plows into an anomalous PWAT environment, but models
need some time to sort that out.

Bottom line is that the remaining melting snow will get flows
within striking distance of exceeding bankfull stages and any
properly located rainfall, in excess of about an inch, would get
a few of those more sensitive rivers to top flood stage. Official
forecasts show the river trends nicely, but are currently valid
only until 12Z Saturday. Crests would be later Saturday, or
Sunday. For now, we will remain conservative in our messaging
of this event, but our partners might want to dust off any flood
hazard and mitigation plans at this time.

&&

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

&&

$$
SYNOPSIS...DGM
NEAR TERM...DGM/MSE
SHORT TERM...DGM
LONG TERM...DJP
AVIATION...DGM/MLJ/MSE
HYDROLOGY...



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