Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Albany New York
936 PM EST Monday Jan 26 2015

Synopsis...
low pressure off the North Carolina coast will rapidly intensify
into a powerful Nor'easter tonight...as it tracks east of Long
Island and eventually Cape Cod. This storm will bring a crippling
blizzard to Litchfield County and heavy snowfall to the remainder of
adjacent western New England and much of eastern New York. The only
exception will be to the north and west of the capital
region...where snow accumulations are expected to be moderate. Snow
will end Tuesday night as the storm pulls away into the Canadian
Maritimes.

&&

Near term /through Tuesday night/...
a major Nor'easter will impact much of the region with heavy
snowfall...and blowing snow resulting from some strong winds.

Trends showing the storm track a little bit more east...based on
all the new guidance and satellite and radar trends. Lowering
snowfall amounts through tonight in eastern New York and southern Vermont...
but waiting for all 00z guidance before decision on whether
adjustments needed beyond tonight...as storm stalling off Cape Cod
tomorrow could still throw some moisture and dynamics westward for
some very dry snow...even if liquid equivalent could be a bit
less. Surface analyses show the upper energy still tracking east
and the surface low well east of the Delaware-Maryland-Virginia...with pressure
falls east...rather than north of the system...suggesting a delay
in the northward shift of the storm track...perhaps partially in
response to the continued feed of dry air from the strong upper
confluence and low level ridging in southeastern Canada.

So...headlines will remain as is...but again amounts reduced
a little because of less snow expected overnight. The band heading
westward now through CT and central Massachusetts should affect northwest CT and the
Berkshires later tonight...so little to no reduction in snowfall
there. Still...all the 00z guidance will be interesting and
forecast will continue to be refined through the night as the
storm evolution continues to be revealed.

Previous discussion below...

Low pressure at the surface has emerged east of the Delaware-Maryland-Virginia...
with the best pressure falls being indicated to the north and
east. The upper level through has already become negatively
tilted...and the middle level circulation will eventually close off
tonight as the surface cyclone rapidly intensifies. Current water
vapor imagery showing an impressive baroclinic Leaf along the middle
Atlantic coast and into southern/central New England. Coupled
upper level jet structure also noted...so there is high confidence
in rapid deepening of the surface cyclone tonight.

There is still some uncertainty with regards to the storm rack...
and resulting quantitative precipitation forecast and snowfall amounts. The European model (ecmwf) continues to
show a more westerly track and the most quantitative precipitation forecast of all the operational
guidance...with a northward jog during the day Tuesday to just
south of Cape Cod. Other guidance and especially the GFS/CMC
indicating a more easterly solution...with resulting less quantitative precipitation forecast for
our area. Sref plumes for alb indicating a wide range of quantitative precipitation forecast
leading up to the storm despite being close in time to initiation
of snowfall. Multi-member probabilistic snowfall guidance from wpc
shows a very tight gradient in snowfall...with the 50th percentile
ranging from 4 inches in the western Mohawk Valley to 24 inches in
Litchfield CT.

Since the storm is still in the developing stages...we are taking a
blended approach to the forecast...while maintaining consistency
with the previous forecast. We realize the European model (ecmwf) would result in
significantly greater snowfall...thus snowfall totals were raised
slightly from close to Albany and for points south and east. We are
now indicating a larger area of 18-24 inches from Dutchess County...
to the central/southern Taconics...southern Windham in Vermont...and
all of Berkshire County. Snowfall in the 18-30+ inch range
expected in Litchfield County CT where the greatest snowfall rates
associated with intense mesoscale banding is anticipated. We are
expecting snow-liquid ratios to be slightly above climatology
around 14 or 15:1.

Cstar research indicates strong and steeply sloped frontogenesis
will result in intense mesoscale banding to the north and west of
the surface/700 mb low center. Although it is too early to pinpoint
exact locations...the highest confidence for banding will be south
and east of Albany especially across the southern Taconics...
Berkshires and Litchfield Hills. Even a slight shift in the storm
track could significantly alter banding/snowfall. Snowfall rates
in the most intense bands could approach 2-4 inches per hour.

The heaviest snow should arrive from southeast to northwest
overnight into Tuesday morning. Snow will start to taper off from
west to east Tuesday afternoon and evening. From mainly the Hudson
River valley eastward...steady accumulating snow should continue
through much of the afternoon hours.

Some lingering light snow or snow showers will be possible Tuesday
evening...before completely tapering off Tuesday night.
North-northwest winds could still result in some lingering
blowing/drifting snow overnight.

&&

Short term /Wednesday through Wednesday night/...
high pressure will build into the region on Wednesday...with
drying conditions and continued below normal temperatures.

The ridge of high pressure translates east across the region Wednesday
nt. Given the fresh snowpack across the region...any period of
light winds and relatively clear skies...even if for only a small
portion of the night...should allow temperatures to plummet. Have
therefore went below a blend of all models for temperatures...with most
mins below zero across the region. Winds will be light...so wind
chill values will be nearly same as ambient temperatures. Some clouds may
increase after midnight in advance of the next system approaching
from the Great Lakes region.

&&

Long term /Thursday through Monday/...
cold and active weather pattern continues through entire long
term period...

Below to well below normal temperatures will dominate the entire long term
period. Also...a clipper type system will bring a chance for
snow...mainly light to moderate in intensity...for the late
Thursday/early Friday...with the possibility of another storm approaching
from the southwest for late sun into Monday.

Here are some more specifics...

Thu-Fri...another clipper type system will approach from the
Great Lakes region. There is some suggestion by the long range
guidance that it may redevelop south of Long Island Thursday nt or Friday.
This may allow some added low level Atlantic moisture to become
infused into the system...especially from the Hudson River and points east
into southern Vermont/western Massachusetts and northwest CT. Several inches of snow could
occur in these areas...with generally lighter amts expected farther
north and west...mainly in the 1-4 inch range. The snow could linger into
Friday am...as another piece of upper level energy approaches from the
northwest and possibly slows down the system. Temperatures should reach the 20s in
most areas on Thursday...and 20s to lower 30s on Friday...although maximum temperatures
may occur in the morning with falling temperatures possible regionwide in
the afternoon.

Friday nt-Sat nt...generally fair but cold conditions. It should be
quite breezy Friday nt/early Sat...and with Arctic air advecting into
the region...some wind chill values could approach or surpass
advisory levels across large portions of the region during the late
day and night periods. Friday and Sat nt mins should fall into the
single digits below and slightly above zero...except in the teens
below zero across the western Adirondacks. Sat maximum temperatures should only
reach the teens in most valleys...and single digits across higher
elevations.

Sun-Mon...some long term guidance suggest that phasing between
northern and southern streams occurs...resulting in a developing
storm system somewhere in the lower Ohio Valley/middle Atlantic region
and then possibly redeveloping offshore. Should this occur...there
may be at least another threat for accumulating snowfall across the
region...especially southern areas. Will keep slight chance to chance
probability of precipitation...highest across S/east areas...for late sun into Monday.
Otherwise...remaining quite cold...with maximum temperatures mainly only
reaching the teens on sun...and single digits to lower teens on Monday.
Overnight mins for sun nt should fall below zero in most
areas...perhaps well below zero across the southern Adirondacks
depending on if clouds with any coastal storm system remain south
and east.

&&

Aviation /03z Tuesday through Saturday/...
major Nor'easter will have a severe impact on all terminals...mainly
for later tonight and especially during Tuesday with snow and some
wind.

Through around midnight...snow will be rather patchy...and mainly be
confined to kalb/kpsf and kpou...and much more limited at kgfl.
Flight conditions during this time will be varying between VFR and
MVFR...although a few periods of IFR visibilities will be possible...especially at
kpou and kpsf. Meanwhile...at kgfl...conditions may remain
VFR...with only some patchy light snow or flurries possible.

Midnight through daybreak Tuesday...bands of snow should begin to
advance northwest across the taf sites. It might take until closer
to daybreak at kalb and especially kgfl. Conditions will trend to
MVFR/IFR as the bands develop and move through.

After daybreak Tuesday...snow should become more widespread...with
some embedded bands of moderate to heavy snowfall intensity
developing during the middle morning hours from southeast to
northwest...with bands of moderate to heavy snow persisting into Tuesday
evening. IFR/LIFR conditions will be likely...both due to falling
snow...as well as blowing snow.

Winds will be mainly from the north to northeast at 8-12 knots
overnight...and may occasionally gust up to 20 knots. Winds will
increase slightly on Tuesday from the north at 10-15 knots...with gusts
of 20-30 knots expected...strongest at kalb/kpsf and kpou.

Outlook...

Tuesday night: high operational impact. Breezy. Likely shsn...sn.
Wednesday: no operational impact. No sig weather.
Wednesday night: no operational impact. No sig weather.
Thursday: moderate operational impact. Chance of snow.
Thursday night: high operational impact. Likely snow.
Friday: moderate operational impact. Breezy. Chance of shsn...sn.
Friday night to saturday: no operational impact. No sig weather.

&&

Hydrology...
no significant Hydro problems are expected through the next five
days.

The precipitation that does occur will be in the form of snow...with
a significant snowfall expected tonight and Tuesday across western
New England and most of east central New York.

Ice will continue to thicken on rivers...streams...creeks...lakes
and other bodies of water.

The Eagle bridge gage on the hoosic river continues to be hampered
by ice effects.

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.

&&

Aly watches/warnings/advisories...
CT...Blizzard Warning until 1 am EST Wednesday for ctz001-013.
New York...Winter Storm Warning until 1 am EST Wednesday for nyz041-043-
047>054-058>061-063>066-083-084.
Winter Weather Advisory until 1 am EST Wednesday for nyz039-
040-042-082.
Massachusetts...Winter Storm Warning until 1 am EST Wednesday for maz001-025.
Vermont...Winter Storm Warning until 1 am EST Wednesday for vtz013>015.

&&

$$
Synopsis...jpv
near term...NAS/jpv
short term...kl
long term...kl
aviation...kl
hydrology...jpv

National Weather Service Glossary of Abbreviations