Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 211129

Area Forecast Discussion
National Weather Service Binghamton NY
629 AM EST Sun Jan 21 2018

Mild conditions will continue this weekend.  Moisture will
increase from the west this afternoon, with increasing odds of
seeing light rain showers or drizzle. As temperatures cool
tonight it could freeze. Rain will be likely Monday and
Tuesday, as a storm system moves through the region. A slightly
cooler airmass is expected behind the system for mid week, along
with scattered snow showers.


330 am update...

Early this morning temperatures again showing a wide range from
around 20 to the mid 30s. Lowered temps. Skies only have high
clouds so little insolation. Winds have become light to calm
across most of the area. Clouds have pushed south into Rome but
should slow with little more progress. A larger area of clouds
in western NY and central PA are moving east to be over our area
today. This will keep temperatures lower than yesterday and
mostly in the upper 30s and lower 40s. Also with the clouds will
be a chance of light rain starting this afternoon. This
afternoon only a chance with the highest chance in the Chemung
Valley and Bradford County PA. The problem with this is surface
temperatures in the far east will be near freezing tonight into
Monday morning. This occurs over the higher terrain from
northern Sullivan County to eastern Otsego County, and then
across most of Oneida County. Lows around 30 tonight there to
mid 30s Elmira to Scranton.

Precipitation associated with a warm front and weak isentropic
lift. Rain chances remain low tonight then become likely in NY
Monday midday into the afternoon as the front lifts through and
we get a brief break. Rain amounts this period range from a
quarter inch in the far north to less than a tenth of an inch
for most of NEPA. Highs mostly in the low and mid 40s.


320 am update... As the main cyclone translates across the St.
Lawrence Valley and towards the north Atlantic this period, a
trailing surface occlusion/cold front will approach CNY/NEPA
from the west late Monday night, then cross the region on
Tuesday. An associated frontal band of steadier rain will shift
across the area fairly quickly late Monday night and Tuesday
morning, with precipitation tapering off and becoming more
showery in nature by afternoon.

It still appears that system movement will be fast enough to
limit rainfall amounts to generally 0.5-0.75 inches in about a
12-hour period, with localized amounts near an inch over
portions of NEPA and the western Catskills in NY. Even with
snowmelt runoff anticipated, such rainfall amounts should, in
general, keep our larger river systems, along with smaller
tributaries, within bankfull. However, what remains a wild card
is ice behavior and how it will respond to increased flows.
Thus, it pays to be vigilant in areas typically prone to ice
jams, and we`ll continue to highlight this situation in our
hazardous weather outlook.


330 am update... Other than blending in the most recent guidance
through about Wednesday, no substantive changes made to the
existing forecast.

A brief return to seasonable temperatures are still expected
during the mid-week period, along with a minor lake-effect snow
episode southeast of Lake Ontario. Readings should moderate
above normal again towards next weekend.

Previous discussion... Cold air advection and a northwest flow
will bring lake effect snow showers into the area into early
Thursday. Air is not all that cold, bottoming out at around -16C
at 850mb, so the lake effect will be limited to snow showers.
Flow becomes more sheared with time as the surface high drops in
with a more northerly flow, and the 850mb and 925mb northwest.
Nose of the surface high will be over the region Thursday night
ending the leftovers. High slides east as the upper ridge builds
on Friday with the warm air advection beginning again in
earnest. This should allow for temps above normal at the end of
the week.


630 am update...

Fuel alternate MVFR cigs at RME this morning will lift remain
MVFR into tonight. some improvement to higher end MVFR this
afternoon then dropping this evening.

Large area of MVFR cigs have moved east into ELM this morning
but should stall into early afternoon before moving to all sites
this afternoon. Cigs probably start as fuel alternate at
BGM/ITH. This evening the rest of the sites go that low then
fall to IFR cigs tonight. Could also be some MVFR fog with moist
ground and maybe some patchy rain. Most likely in NY. RME could
have freezing rain late tonight.

SW winds at around 5 kts or light and variable this morning.
This afternoon winds shift to the south but still light or light
and variable, and continue tonight.


Monday through Tuesday...Flight category reductions continue
under periods of RA.

Tuesday night through Wednesday...Possible continuation of
flight category reductions and a chance of SHSN.

Thursday...VFR under high pressure.




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