Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
1248 am EST Friday Dec 6 2013
a cold front will slowly move across most of eastern New
York and western New England tonight...as a low pressure system
moving along the boundary will bring rain showers...and perhaps a
brief mixture of wintry precipitation to the southern Adirondack
region late tonight. Another low pressure system will move along the
frontal boundary tomorrow afternoon into the evening bringing mainly
snow from the capital region north and west...and a wintry mix to
the south and east. High pressure will build in from the northern
plains and upper Midwest with colder and drier weather for Saturday.
Near term /until 6 am Friday morning/...
as of midnight...the cold front has just crossed Albany
international Airport heading southeast. This feature will have
worked across our entire County Warning Area by daybreak.
Not a whole lot of rain associated with it but a wave riding just to
the south of area should enhanced the rain a little overnight.
Still...decided to back off the quantitative precipitation forecast a little since it has yet to
Cold air coming in but not excessively fast. Still around 40 in
northwestern areas...50s from Albany southward. Temperatures will
slowly fall to around freezing Alabama little lower well north and west
by daybreak...closer to 40 in the capital region...40s south.
Precipitation will change to a wintry mix north and west...but with
light amounts and the fact that it looks to be a mainly rain to
sleet to snow transition not expected much if any freezing rain...no
need for any advisories. Only looking for an inch or two of snow at
most...mainly across the Adirondacks.
So for this update...no major changes...just minor adjustments of
the cold front passage...and precipitation changeover.
Short term /6 am Friday morning through Saturday night/...
tomorrow to tomorrow night...complicated forecast with frontal
boundary passing south of most of the forecast area in the
morning...and another wave of low pressure approaching from the
Piedmont region. Their will likely be a lull in the precipitation in the
late morning into the early afternoon with some drier air filling
in from the north and west. The probability of precipitation were tapered down to slight
or low chance values for showers. A non-diurnal trend for temperatures was
used...as they might be steady or only slightly rise a few degrees
in the morning...before falling in the PM with the the low level
colder air moving into the region.
In the afternoon...over running precipitation starts to quickly build back
into the region from the south to southwest to the north to
northeast. Locations from Mohawk Valley...Lake George region south
and east will start out as rain...but gradually turn over to snow
as the column cools down. Critical partial thicknesses from the
GFS/NAM support mostly snow over the northern zones late in the day.
The challenge will be towards nightfall where the rain may not go
over quickly to snowfall south and east of the capital
region...but mix with some sleet and freezing rain. An advisory
may be needed for mix precipitation...for locations south and east of the
capital region Friday night. This is in the 3rd period...and we will
further examine if an advisory is needed here later in time.
Friday night...a decent burst of snowfall is anticipated over the
capital region...northern and eastern Catskills...southern Vermont...northern
Catskills...Mohawk Valley and the Lake George Saratoga region where
2 to 4 inches will be possible. Some 3-6 inch amounts may be
possible over the northern and eastern Catskills...and helderbergs. Lesser
amounts of snowfall on the order of an inch or two is expected
over the southern dacks. The best qg lift on the GFS/European model (ecmwf) moves
across the central and southern portions of the forecast area. Snow ratios of
10-12:1 were used for most of the event. Accumulations of sleet up to
an inch will be possible over parts of the middle Hudson
Valley...Taconics...Berkshires... and northwest CT. Also...light ice
accumulations may be possible over the Litchfield Hills...southern
Berks...southern Taconics...and eastern Catskills. The GFS thermal profiles
were used in a top down fashion. The ptype could change a lot
depending on the actual depth of subfreezing air...and where the
boundary sets up with the wave moving along it. The severe weather potential statement will
highlight this time frame for a possible advisory for portions of
the forecast area. Lows Friday night will range from the upper teens
to lower 20s over the northern zones...and mostly middle and u20s from the
Mohawk Valley/capital region south and east.
Saturday...a large dome of Canadian high pressure builds in from
the upper MS River Valley...and northern plains. Cold and brisk
conditions will open the weekend with h850 temperatures down to -5c to
-10c south and east of aly...and -10c to -15c north and west. Some
northwest flow lake effect snow showers or flurries are possible over the
southern dacks...and the western Mohawk Valley. Slight and low chance probability of precipitation
were used here. Temperatures will range from the m20s over the southern
dacks...to u30s over the middle Hudson Valley and northwest CT.
Saturday night...the low and middle level flow turns anticyclonic with
high pressure building in ending lake effect activity before
midnight. Mostly clear and light wind conditions should yield
favorable radiational cooling conditions with lows in the teens for
most of the region with single digits over the southern dacks.
Long term /Sunday through Thursday/...
the weekend ends on a tranquil note...then winter comes in like a
lion. High pressure retreats quickly as the weekend comes to an
end...with two storm systems heading for the northeast at the same
time...one from the southern rockies...and the other from the Gulf
Coast region. The result will be a high likelihood of a wintry mix
of precipitation Sunday night and Monday...followed by a cold
frontal passage...and a changeover to snow showers Monday night.
The onset of a prolonged westerly flow will set the stage for
significant lake effect snow for the western Adirondacks into the
Mohawk Valley beginning on Tuesday...which is expected to last
through the remainder of the extended period. Areas from Glens
Falls south and east should be dry...but still cold...through this
lake effect period.
High temperatures mostly in the 20s and lower to middle 30s on Sunday
will moderate to the 30s and lower 40s on Monday. Temperatures then
dive...with highs on Tuesday mostly at freezing and lower. Highs by
Thursday will range from only the middle teens in the Adirondacks and
greens...to the middle and upper 20s in the middle Hudson Valley. Low
temperatures will become even more impressive...with lows Sunday and
Monday nights from the middle teens to middle and upper 20s. These
readings will fall back another 10 to 15 degrees for Tuesday night
with most locations getting down into the single digits. Wednesday
night...lows will dip to just below zero across most of the
Adirondacks and high points of The Greens...with single digits to
around 10 degrees above zero everywhere else. Normal highs in
Albany during the period are in the upper 30s...with normal lows in
the middle 20s.
Aviation /06z Friday through Tuesday/...
cold front was just clearing the capital region of New York as winds
have quickly shifted from south to west-northwest as this trend will
continue for the remainder of the taf locations this early Friday
morning. Precipitation shield is lagging a bit per the regional radars
which remains along and west of i81. Experimental reflectivity
forecasts suggest this should fill in and track across the region
overnight as we will keep flight conditions into IFR/low-end MVFR.
The rain showers should end by the middle morning hours as ceilings should
be high end MVFR or low end VFR through much of the daylight hours
Friday and little to no precipitation will occur through much of the day
/exception could be kpou with closer proximity of the front and kpsf
where upslope conditions will be present/. However...another wave of
low pressure will approach for late Friday aftn/evening...with
another round of precipitation /mainly snow for kalb/kpsf/kgfl and
rain to snow for kpou/ for Friday evening into Friday night.
Friday night: high operational impact. Definite snow...sleet.
Saturday: low operational impact.Breezy no sig weather.
Saturday night: no operational impact. No sig weather.
Sunday: no operational impact. No sig weather.
Sunday night: high operational impact. Definite snow.
Monday: high operational impact. Definite rain...sn...sleet.
Monday night: moderate operational impact. Chance of shsn.
Tuesday: no operational impact. No sig weather.
no Hydro related concerns are expected over the next 5 days.
Tonight...a cold front gradually pushes through our region...a
wave of low pressure moving along it will likely produce a tenth
of an inch to a half inch of quantitative precipitation forecast...with rain the predominant ptype
with a light mixture over the southern Adirondack region.
Friday-Friday night...another wave will move along the boundary with
another tenth to half an inch of quantitative precipitation forecast. The heaviest quantitative precipitation forecast looks like
it will be over the southern and central half of the hsa. Much of this
precipitation may fall as snow or sleet with some rain and freezing rain
mainly south and east of the capital region. Significant within
banks rises are not expected with most of the nerfc hydrographs
showing 1 to 2 foot rises...especially south and east of the
capital region. Total quantitative precipitation forecast for both events looks to be in the
quarter to three quarters of an inch range with locally higher
amounts up to an inch.
It will then turn colder after this system finally pushes through
Friday night. It looks mainly dry Saturday into Sunday before the
next strong storm system approaches Sunday night into Monday. It
looks cold enough for mainly snow and/or mixed precipitation to
fall with this system at this time...and possibly ending as some
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 website.