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Area forecast discussion 
National Weather Service Albany New York
927 PM EST Tuesday Nov 25 2014

Synopsis...
a coastal low will bring a widespread snowfall to the area that will
significantly impact Holiday travel Wednesday and Wednesday night.
Heavy snowfall is expected across western New England and much of
eastern New York with the heaviest snow occurring the afternoon into
the evening. The snow is expected to taper late Wednesday
night...with some lingering snow showers across the area for
Thanksgiving day.

&&

Near term /until 6 am Wednesday morning/...
colder air filters in helping to set the stage for a widespread
snowfall. Satellite imagery showing middle and high clouds building
north and northeast from the southeastern U.S. And stratocumulus
edging east from the Great Lakes. Most areas should be cloudy
before midnight...which could limit the cooling across the region.
Although...still some cold advection occurring as west low level
wind flow and cooling boundary layer temperatures spread across
the region through the night. Some minor adjustments to
temperatures through tonight.

Will be tracking the northwestern edge of the upper deformation
zone developing in the southeastern U.S. To get a feel for the
northwestern extent of the heaviest snow as the upper deformation
tracks toward the northeastern U.S. Interesting water vapor
imagery shows 2 closed upper vorticity centers lined up from just
north of the Great Lakes through eastern Canada...so will the
extensive line of shear associated with strong upper jet energy
along the eastern U.S. Help the upper deformation in the upcoming
storm to become a closed vorticity center like the ones
downstream? If so...perhaps the upcoming storm could have more
upper dynamics and build the heavier precipitation further north.

That would be a bit different than the open wave all the guidance
suggests associated with the upcoming storm...but just have to
watch trends to refine the forecast through the night. Lows in
the 20s north to lower to middle 30s central and south.

Based on the latest radar and satellite trends and latest hrrr and
local WRF...the onset of the snow could be more around sunrise
rather than before sunrise in southern and central areas. Clouds
will also thicken and lower tonight. So...light precipitation
should begin to move into the central and southeastern
Catskills...middle Hudson Valley...Litchfield County and southern
Berkshires around sunrise with some mixed possible of snow...rain
and sleet to start. Some minor adjustments to the forecasted
onset later tonight and tomorrow morning.

&&

Short term /6 am Wednesday morning through Thursday night/...
winter storm warnings and winter weather advisories remain in
effect.

The highest snowfall amounts are expected across the western New
England...the Taconics...the higher terrain of the central and
southeastern Catskills and portions of the middle Hudson Valley.
Amounts will decrease as you head northwest across the forecast area
away from the coastal low with the gradient between warning level
and advisory level snowfall expected to occur in the vicinity of the
Schoharie valley...capital district and Lake George Saratoga area.
This is why the Winter Storm Watch was in effect as long as it was.

Miller type a coastal low tapping Gulf moisture. Southern stream
energy is initiating the developing of a low along the Gulf
coastal along a stalled frontal boundary. The low will track
northeastward and deepen. The guidance has come into good
agreement on the track...position and strength of the storm
passing the low just south of Cape Cod Wednesday evening. The
differences are occurring in the quantitative precipitation forecast. Guidance also continues to
indicate banding will occur especially for areas to the south and
east of the capital district hence the higher snowfall forecast.
Snowfall rates of up to an inch an hour are expected expected at
times across portions of the warning area with around 2 inches an
hour possible south and east of the capital district where banding
is more likely.

Snow ratio will be lower across the middle Hudson and northwestern
Connecticut and with the higher totals and stronger winds some
isolated power outages can be ruled out.

Approaching northern stream energy does not phase with the
southern stream keeping storm progressive but will bring chances
for snow showers to the region for Thanksgiving day and night
especially across the higher terrain.

Little recovery in temperatures Wednesday upper 20s to middle 30s.
Much colder air will not be drawn into the region under after the
northern stream energy moves off to the east.

&&

Long term /Friday through Tuesday/...
the long term period will be characterized by periods of unsettled
weather...as a series of fast-moving systems impact the region.

At the start of the long term period...in the wake of the coastal
storm that impacted the region in the short term period...the
forecast area will be underneath a northwest flow regime that will
gradually be deamplifying heading into the weekend. By the
weekend...the flow will become quasi-zonal...allowing for fast
pieces of northern stream energy to move through it...in which the
timing and impacts of these features could change over the next few
days as medium-range guidance often struggles handling fast zonal
flow. The first of these pieces of energy will affect mainly areas
north and west of the capital region Thursday night...as an
upper-level shortwave races through the northwest flow providing a
period of scattered light snow showers. Accumulations with this
feature will be light...on the order of an inch or two across
portions of the southern Adirondacks...and a dusting to perhaps an
inch across portions of the Mohawk Valley and Lake George/Saratoga
region.

Much of the region looks to be dry during the day Friday...except
for some scattered lake effect snow showers that may skirt portions
of Herkimer County downwind of Lake Ontario. The next system looks
to impact the region for much of the weekend as an area of low
pressure tracks northeast from the Central Plains to the Great
Lakes. Out ahead of this low pressure system...warm air advection
precipitation ahead of an approaching warm front may allow for scattered
rain/snow showers Saturday into Saturday night. Not much
moisture/dynamics will be present with this boundary as the low
pressure center will be lifting far north and west of the region.

During the day Sunday...the warm front should lift north across the
region...ushering in another short period of mild weather with
scattered rain/snow showers. High pressure looks to build across the
region for the start of next week resulting in a period of dry
weather into the middle of next week.

High temperatures throughout the long term period will generally
range from the upper 20s to upper 30s...except on Sunday where highs
will range from the upper 30s to near 50 in valley areas and low 30s
to middle 40s Monday. Low temperatures will generally range from the
middle teens to low 20s except for upper 20s to middle 30s Saturday and
Sunday nights.

&&

Aviation /02z Wednesday through Sunday/...
VFR conditions will continue through the evening hours. Middle and
high level clouds will continue to increase over the area from the
South. West-SW winds will be around 5-10 kts for this evening due to
the loss of daytime heating/mixing.

During the overnight hours...lower clouds will continue to increase
from south to north...especially by late tonight. VFR conditions will
continue through most of the overnight hours. Some light snowfall
may start to reach towards kpou towards daybreak Wednesday. Once
snow begins...it will quickly reduce visibility down to IFR conditions.
Winds will become light for late tonight...and become north-NE for
Wednesday morning...generally around 5 kts or less.

Snow will move from south to north through the morning hours...
reaching kpsf around 13z...kalb around 14z and kgfl around 16z.
All areas look to see IFR conditions shortly after snow begins.
Snow will increase in intensity several hours after beginning...
becoming moderate to locally heavy for the afternoon hours. Winds
should turn to the north in the morning and continue at around 5
knots through the day.

Outlook...
Wednesday night: high operational impact. Definite snow.
Thanksgiving day-night: low operational impact. Slight chance of shsn.
Fri: no operational impact. No sig weather.
Sat-Sat night: low operational impact. Slight chance of shsn.
Sun: low operational impact. Slight chance of rain showers...shsn.

&&

Hydrology...
no significant hydrologic problems are expected through the
weekend.

Widespread snowfall as coastal low impacts region Wednesday and
Wednesday night. Warmer temperatures Sunday will be short lived
and will result some snow melt and ripening of snow pack. However
temperatures are expected to be in the middle 30s and colder Saturday
night and Sunday night so melt is stop.

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...Winter Storm Warning from 5 am Wednesday to 7 am EST Thursday
for ctz001-013.
New York...Winter Storm Warning from 5 am Wednesday to 7 am EST Thursday
for nyz058>061-063>066.
Winter Storm Warning from 7 am Wednesday to 7 am EST Thursday
for nyz047>054-084.
Winter Weather Advisory from 9 am Wednesday to 7 am EST
Thursday for nyz032-033-038>043-082-083.
Massachusetts...Winter Storm Warning from 5 am Wednesday to 7 am EST Thursday
for maz001-025.
Vermont...Winter Storm Warning from 5 am Wednesday to 7 am EST Thursday
for vtz013>015.

&&

$$
Synopsis...iaa
near term...iaa/NAS
short term...iaa
long term...irl
aviation...NAS
hydrology...iaa

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