Scientific Forecaster Discussion
fxus61 kbgm 201751
Area forecast discussion
National Weather Service Binghamton New York
1251 PM EST Fri Jan 20 2017
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 /Saturday night through Monday/...
410 am update...
clouds will not be going anywhere, but Saturday night through
Sunday morning will at least be mainly dry. Despite a brief ridge,
shallow moisture will stay trapped under a subsidence inversion.
However, rain chances will begin to increase midday Sunday Onward
with the arrival of deeper moisture, and weakening/shifting of
the ridge well ahead of our next system. Temperatures will be very
mild, with upper 30s-lower 40s Saturday night followed by mainly
mid to upper 40s Sunday.
Long term /Monday night through Thursday/...
410 am update...
forecast adjusted to account for latest multi-model trends.
Coastal low remains the main concern late Sunday night through
Tuesday. While confidence continues to increase in a solid round
of precipitation, there is a large spread in possibilities for
precipitation types and amounts of each. It also appears that a
nose of near-to-above freezing temperatures aloft could introduce
sleet and perhaps eventually freezing rain into the equation,
especially east of I-81. Overall trends suggest that snow
accumulations will have a large elevation dependence, and that
snow will be of low snow-to-liquid ratios. That is, it will be
rather dense stuff. Sleet has been added as a potential weather
type during much of the period especially Catskills-Poconos, in
addition to the snow-or-rain likelihoods across the region.
One other item that gives ME pause, is the very anomalous
easterly component of the 850mb jet in the GFS ensembles; to the
tune of 5 Standard deviations. This is often a hallmark of the
more interesting weather events in our region, and certainly
suggests significant injection of Atlantic moisture. We will have
to continue to monitor for potential localized excessive rainfall,
which of course itself is a question mark because of uncertainty
even in precipitation type. Hydrology-wise, solid rises can be
expected in area rivers in streams, again especially along and
east of I-81; but it remains to be seen if anything worse than
that is in the cards.
the big change with the 12z model cycle is that the GFS has
trended farther S/east with the coastal low allowing colder
temperatures to filter into the area faster from the NE. This is
in line with the trend we've also seen with the European model (ecmwf) and Gem
global models. That said, the system is still several days out
with the energy that will initiate this system still over the
Pacific so it is early to have high forecast confidence. That
said, in the bigger picture, models in overall good agreement in
tracking broad coastal low from the southeast states late Sunday
northeastward to around the Delmarva region by late
Monday...bringing the storm's precip shield into the forecast area
from south to north Sunday night into Monday. At the same time,
trend will be for colder air from the NE to filter into the region
which will also be aided by the dynamic cooling from the system
itself. This all said, temperatures will still be be very marginal
so in terms of the gridded forecast, will forecast rain changing
to mixed rain/snow Sunday night into Monday with mostly snow by
Monday night. If colder trend continues, however, it is possible
change to snow could occur earlier. Also still early to be
confident in liquid precip amounts since County Warning Area looks to be near the
north/west edge of the storm's heaviest precip. However, potential still
exists for significant amounts. Best chance of seeing heaviest
snow amounts looks to over the Poconos and the Catskills.
Coastal system winds down to rain/snow showers by Tuesday as low moves
east of New England. There will likely be a brief break before a
weaker system brings a chance for rain/snow showers by later
Wednesday into Thursday. Temperatures generally remaining warmer
than normal for this time of year with highs in the 30s and a
narrow diurnal range in temps.
Aviation /18z 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.
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.