Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 210045

Area Forecast Discussion
National Weather Service Binghamton NY
745 PM EST Fri Jan 20 2017

Mostly cloudy skies with locally dense fog will prevail through
the night. Saturday looks mild and generally rain-free. Rain, or
perhaps a wintry mix, may develop by later Sunday, with a
developing storm system across the southeastern states.


740 PM EST Update...
Forecast is in great shape. Lowered pops from the previous
forecast to match current observations on the radar. Showers from
this afternoon have diminished across the region and copious
amounts of low-lvl moisture linger in its wake. Overcast skies
with patchy drizzle and locally dense fog are still expected to
prevail through the reminder of the night. Temps are currently in
the mid to uppr 30s with dew points ranging in the low to mid 30s.
These temps will hold fairly steady over the next few hours, but
then start to rise after midnight as WAA continues across the
region. Overall the previous forecast is in great shape. For more
information about the previous forecast, please read the previous
forecast discussion below.

Previous forecast discussion...
Later tonight, plenty of low-level moisture is likely to get
trapped underneath a subsidence inversion 3-5 thousand feet above
ground level. As a result, widespread lower stratus clouds are
expected, along with patchy drizzle and locally dense fog,
particularly over the higher terrain.

Temperatures are not likely to move much overnight, with low-level
warm advection at play, and in fact they may even rise a few
degrees during the pre-dawn hours.

Saturday and Saturday night should remain quite mild for late
January, with readings in the 40s much of the time. Again, plenty
of lower clouds should hang around, with lots of low-level
moisture and further warming aloft. Although patchy drizzle can`t
be ruled out from time to time, much of this period should end up
precipitation free. Also, locally dense fog may form again later
Saturday night over the higher terrain.


Main focus continues to be large coastal storm expected to impact
the area beginning Sunday night and lasting Monday into Tuesday.
There is still a lot of uncertainty but we continue to monitor the
potential for heavy rain, a wintry mix, and even some snow to
affect the area. Forecast models differ in details, as discussed
below, but we still see the potential for 1-2 inches of liquid
precip falling with this system over parts of the area.

To start the period, conditions will be fairly quiet for a good
part of Sunday. Abundant low level moisture will keep stratus in
place but mostly dry weather will persist through a good part of
the day with temperatures in the 40s.

Expect northern edge of the precipitation shield with the coastal
storm to begin moving into the CWA from the south late day Sunday
into Sunday night as large, deepening low moves northeast from
Georgia to near Virginia by early Monday. The low will be closed
off aloft helping to slow it down. Forecast models models are in
good general agreement on this overall scenario. Also, since the
system will be moving into a mild airmass, expect that most areas
will begin as rain as precip first moves in.

The big question is still on how the storm will evolve as we head
into the day Monday. The GFS keeps temperature warm enough at the
lowest levels to result in mainly rain continuing through the day
while NAM indicates cold air in the lowest levels will slowly
funnel down from the NE while a warm layer moves in near 800 mb -
the colder low levels due in part to a slightly farther east
position with the low. This would suggest a rain changing to sleet
scenario..beginning in eastern zones through the Catskills early
in the day and possibly encompassing much of the area by late day
as surface temps drop to near freezing. Freezing rain would also
be possible though at this point soundings suggest sleet a higher
likelihood. In terms of the GEM and EC model solutions, EC leans
toward a warmer solution while GEM is colder over a good portion
of the area as it also moves low a bit farther east by late
Monday...east of the Delmarva. The upshot, is that we continue to
use a model blend approach for the gridded forecast however I did
trend surface temps slightly toward the NAM as historically this
model handles inversions with low level cold air fairly well. In
terms of sensible weather, most areas should still be seeing rain
early in the day but we introduce a wintry mix with a
rain/snow/sleet mix by late day - best chances for accumulating
snow/sleet over the higher terrain of the Poconos and Catskills.
Again, confidence in these specific details remains low due to
marginal temps both at the surface and aloft.

Heading into Monday night, this looks to be when the meat of the
heaviest precip falls over the area as low slowly tracks from
near the mid Atlantic northeast to near Long Island by early
Tuesday. Again, with the details of the exact track and resulting
thermal profiles being uncertain, precip types remain uncertain
but overall trend will be for temps to cool by early Tuesday with
precip trending more toward snow/sleet. Lows will be in the low

For Tuesday, heaviest precip begins to wind down to rain/snow
showers as low moves east of New England. Temps remain in the 30s.
All told, still see the potential for 1-2 inches of total precip
over parts of the which would result in a solid rise on the
rivers. Best chances for heavy precip would be NE PA into the Twin
Tiers as well as the Catskills. Hydro wise, still early to say
whether anything worse would result with any flooding problems but
this will be closely monitored. Finally, it should be noted E/NE
winds will be fairly strong with this system Monday into Monday
night which could add to impacts.


A brief break will be possible late Tuesday into early Wednesday
before the next system brings a chance of rain/snow showers by
late Wednesday into Thursday. Temperatures will remain above
average through the middle of the week with the trend being toward
colder, more seasonable weather by late next week as an upper
trough sets up in the east. This would bring the chance of lake
effect snow showers by Friday.


The light rain showers that have moves across the region earlier
today have pretty much diminished across NEPA and central NY this
evening. Expect all lingering showers to continue to dissipate
over the next few hours. BR is possible this evening as copious
amounts of low-lvl moisture is trapped over the region. This
trapped low-lvl moisture will also result in a fuel alternate and
IFR ceilings through sunrise. Flight conditions will remain near
IFR for most sites through at least 16Z Sat afternoon. Flight
conditions are expected to improve slightly Sat afternoon, but
then deteriorate near sunset. Winds will be light and variable
through the forecast.

Saturday night through early Sunday...Restrictions likely to
continue in lower ceilings and areas of fog.

Late Sunday, Monday, and into Tuesday...Restrictions likely in
rain or a wintry mix.

Wednesday...More restrictions possible in rain or snow showers.




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