Scientific Forecaster Discussion
fxus61 kaly 061509
Area forecast discussion
National Weather Service Albany New York
1009 am EST Tue Dec 6 2016
high pressure over the region will shift off to the east during
the day today. A quick moving low pressure system will bring
the area another period of light snow to the area tonight into
early Wednesday morning. Another low pressure system will move
across the region Thursday with lake effect snow developing in its
wake as much colder air is ushered in across the relatively warmer
waters of the Great Lakes.
Near term /until 6 PM this evening/...
ridging at the surface and aloft will quickly shift offshore today
as a fast moving southern stream short wave trough approaches. It
will remain progressive and will weaken as it encounters the
ridge. The primary low will be weak with secondary development
occurring along the southeast by late in the day.
Widespread sunshine over the region this morning but high clouds
rapidly spreading northeast will cover our region by late this
afternoon. Temperatures have risen steadily and have adjusted some
temperatures through this afternoon. Also some minor adjustments
to sky cover basd on trends. More details in the previous afd
Dry weather is expected with some chances for light precipitation
late in the day into the eastern Catskills and Mid Hudson valley.
Current cloud cover will decrease however high and mid level
clouds will overspread the region ahead of the approaching system.
Looking at another day with seasonable temperatures in the mid 30s
to lower 40s. Winds will be light.
Short term /6 PM this evening through Thursday/...
another round of light snow tonight into early Wednesday morning.
The short wave will dampen out as it moves off the coast and the
coastal low will become the primary low as it tracks eastward out
to sea. The precipitation is expected to be light across the local
area. A period of light snow is expected with likely pops
overspreading the forecast area from southwest to northeast in the
evening. Looking at 1 to 2 inches of snow by around sunrise and
for the morning commute with the higher amounts across the central
and southeastern Catskills. The snow will taper off during the
morning and with rising temperatures rain will mix with a
changeover possible before ending. Will have a lull in precipitation
Wednesday afternoon night as the region is between systems.
A large stacked low is move gradually eastward across the Great
Lakes and eastern Canada through Thursday. Short waves will be
rotating about the low and southern stream energy will join in
resulting in secondary development beginning off the northern New
England coast by late in the day Thursday. With height falls
across the region expecting increasing chances for showers, mainly
snow showers with low level flow becoming favorable for lake
enhancement of snow into the western adirondacks; the far
northwest corner of the forecast area.
Overall temperatures will be seasonable for early December.
Long term /Thursday night through Monday/...
cold air advection continues Thursday night into Saturday as the
upper trough moves overhead, with 850 mb temperatures falling to
near -15c by 12z Saturday. This airmass will be the coldest of the
season thus far, with low temperatures Friday and Saturday night in
the single digits and teens, and highs in the 20s and 30s. A
moderate wind will cause wind chills to feel even colder. The cold
air will result in a Good Lake effect response - Lake Ontario
average surface temps around 8c result in surface to 850 mb Delta-T
values increasing to 20 to 25c. Westerly flow Thursday night will
favor northern Herkimer and Hamilton counties for accumulating snow.
Models suggest a surface trough causing the low-level flow to veer
to northwesterly early Friday, which should result in accumulating
snow shifting southward into the Mohawk Valley and Catskills, and
perhaps some upslope snow into higher terrain of The
Greens/Berkshires as well. Expect some degree of snow shower
activity to continue into Saturday, especially over western portions
of the forecast area.
High pressure should build in briefly Saturday night, but active
weather looks to resume Sunday into early next week as medium-range
deterministic models and ensembles indicate a wave zipping through
the fast upper flow and amplifying over the eastern Continental U.S.. still
plenty of uncertainty as to where this amplification occurs, but
potential is there for widespread precipitation developing in the
period centered around Sunday night. With antecedent cold airmass in
place, a frozen p-type looks probable, but will leave the door open
for liquid as well if the system develops over the western Great
Lakes (e.G., 00z gfs) and puts US in the warm sector.
Aviation /15z Tuesday through Saturday/...
mainly VFR conditions this morning as high pressure is resulting in
diminishing cloud cover, although MVFR/IFR br is being reported at
gfl. High pressure over the region should result in mainly VFR
conditions continuing after daybreak, though forecast soundings are
indicating the potential for some MVFR cloud cover (which was
observed upstream beneath the surface high over Ohio/PA yesterday) as
increasing subsidence lowers inversion heights. For now, have scattered
MVFR clouds and will monitor trends. Mid/high cloud cover will
thicken during the afternoon ahead of a storm system moving into the
region from the mid-Atlantic. This system will weaken as it
approaches, but light precipitation is expected to spread from
southwest to northeast late in the taf period as a -ra/snow mix for
alb/pou, and mostly -sn for gfl/psf. Potential for IFR conditions to
develop late in the taf period due to a mixture of vsby restrictions
in -sn/br as well as cigs.
Light easterly flow will develop today ahead of the approaching low
Wednesday night: no operational impact. No sig weather.
Thursday: moderate operational impact. Chance of rain showers...shsn.
Thursday night: moderate operational impact. Chance of shsn.
Friday: moderate operational impact. Chance of shsn.
Friday night: moderate operational impact. Chance of shsn.
Saturday: no operational impact. Slight chance of shsn.
active week with unsettled weather as a couple more systems impact
the region followed by the development of a lake effect snow event
Thursday night into Friday night. Precipitation will fall mainly
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
advanced hydrologic prediction service /ahps/ graphs on our