Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 202108
AFDBGM

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

.SYNOPSIS...
A passing warm front will bring a period of rain into this
evening. 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.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
1245 pm update... A band of rain continues to make steady progress
into the region this afternoon. Although the large-scale forcing
mechanisms supporting this area of rain should weaken over time,
we still expect light rain to persist over much of the forecast
area until early evening.

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.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
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
30s.

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.
&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...

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.
&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Widespread restrictive conditions will continue through 18z
Saturday, and very likely beyond.

This afternoon, mostly MVFR restrictions are anticipated in light
rain, although occasional IFR can`t be ruled at KBGM.

Tonight and Saturday morning, conditions should deteriorate, with
widespread IFR or worse foreseen. In fact, below alt mins are
likely at several sites.

Conditions may gradually improve after 15z Saturday, with
generally IFR or MVFR anticipated at that time.

OUTLOOK...
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.

&&

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

&&

$$
SYNOPSIS...MLJ
NEAR TERM...MLJ
SHORT TERM...PCF
LONG TERM...PCF
AVIATION...MLJ



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