Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
636 am EST Wednesday Dec 18 2013
an upper level disturbance crossing the region will bring
scattered snow showers...especially this morning. Lake effect snow
showers or snow squalls will impact portions of the western
Adirondacks this afternoon and tonight. High pressure will build
in from the southwest for Thursday...bringing milder
temperatures...and dry conditions. A frontal system approaching
from the west and north will bring clouds...along with some snow
and rain showers for Thursday night into Friday.
Near term /until 6 PM this evening/...
as of 630 am EST...partly to mostly cloudy skies continue across
the region...with scattered snow showers and flurries. Temperatures are
ranging between 5 and 15 above zero for areas near and north of
Interstate 90...and 15 to 20 to the south...and across much of
western New England.
Over the next few hours...the combination of the middle/upper level
trough with an embedded shortwave...and also enhanced low level
convergence with the approach of a weakening occluded frontal
boundary from the west/southwest should allow for snow showers
and/or flurries to increase in areal coverage across the region.
Some minor accums of a dusting...to a few tenths of an inch could
occur from these snow showers/flurries...especially across higher
elevations of the Adirondacks...Schoharie valley and
Catskills...and possibly in valley areas from Albany north.
As the upper trough...and associated remnant occluded boundary
slowly move through...the very cold boundary layer which remained
in tact since yesterday should erode. Some breaks in the clouds
may develop later this morning into the afternoon...especially in valley
areas south of Albany...as some subsidence develops in the wake of
the trough passage. However...some lake response will develop as
cooling within the 850-700 mb layer combines with an increasing
low level over water trajectory across Lake Ontario...with some
additional moistening from Lake Huron. It appears that the lake
effect potential for single snowbands will be for a somewhat short
duration...mainly after 9 am EST today...through at least 6 PM
EST. Expect several inches of snow across portions of northern
Herkimer Colorado...and possibly extending into portions of west central
and northwest Hamilton Colorado...mainly this afternoon. Some extension
of a snowband may also impact portions of the Mohawk
Valley/capital region later this morning or afternoon...with minor
accums possible. Enhanced upslope across portions of southern Vermont
could also lead to an additional 1-3 inches of snowfall across
eastern portions of Bennington Colorado and west central Windham Colorado this
As for temperatures...have sided a bit below a mav/met MOS blend...with
upper 20s to lower 30s expected in most valley areas...and mainly
20s for higher elevations.
Short term /6 PM this evening through Friday night/...
tonight...the aforementioned snowband will likely be ongoing this
evening across the advisory area...and lifting
northward...impacting areas near and north of Route 28. Later
tonight...it appears that the band should weaken as the inversion
level drops rapidly...and low level directional shear increases
and disrupts single band potential. Elsewhere...expect partly
cloudy skies...although some periods of mostly clear skies will be
possible. Given our deep...fresh snowpack...any breaks in the
clouds will allow temperatures to quickly drop. Have therefore went below
the coldest guidance...with mainly single digits and teens
expected. Should breaks in the clouds be more widespread and/or
longer in duration...even colder min temperatures would be possible.
Thursday...low and middle level warm advection develops and strengthens.
As milder and increasingly moist air moves over the very cold
ground and deep snow cover...it appears that a low level inversion
will develop...leading to mostly cloudy skies for at least the
northern third of the region...with occasional clouds to the
south. For maximum temperatures...have sided with the cooler of the mav/met
MOS...with generally 30s expected for valley areas...and 20s to
around 30 for higher elevations.
Thursday nt-Friday nt...a frontal boundary will gradually approach from
the north and west...as waves of low pressure travel along it. Several
surges of isentropic lift will impact the region...especially northern
and central areas. It appears that the best chance for precipitation will be
late Thursday nt into Friday evening. Warming aloft could allow for some
mixed precipitation to occur across northern areas Thursday nt...and again Friday
nt...and will have to watch model trends and low level thermal
profiles. Quantitative precipitation forecast looks light at this time...but can not rule out some
areas of light icing...especially Friday nt across portions of the southern
Adirondacks and western Mohawk Valley. Have sided with...or went
below the cooler mav/met...with nighttime mins falling into the
20s in most areas...and maximum temperatures ranging from the upper 20s to
middle 30s across northern areas...and middle 30s to middle 40s across
Long term /Saturday through Tuesday/...
still decent agreement in guidance and ensembles for a strong warm
advection event that should result in more rain than wintry
precipitation. One system will be exiting through Saturday morning
with just scattered rain and snow showers ending. The next
system...with southern stream origins...spreads mostly rain over
much of the region Saturday afternoon...starting as a mix in the
southern Adirondacks. There could be minor to moderate accumulations
of mixed precipitation...including possibly freezing rain...in the
southern Adirondacks through Saturday night before precipitation
turns to rain Sunday morning.
This could be a prolonged event...with a very strong west
southwesterly boundary layer jet and deep moisture...along with
strong isentropic lift within the warm advection...and strong
frontogenesis along the cold front. There could be enough rain for
some potential run off problems when combined with snow melt. The
axis of heaviest rain looks to be along and north of the Schoharie
valley...southern Adirondacks...helderbergs to the Lake George
Saratoga region...southern Green Mountains and Berkshires. Some
indications are that the heaviest rain could be mostly the extreme
northern sections of the forecast area...so there is considerable
uncertainty on where the heaviest rain could fall. The potential for
heavy rain...snow melt and run off will be addressed in the severe weather potential statement.
Highs Saturday in the 40s...middle to upper 30s southern Adirondacks
and southern Green Mountains. Highs Sunday in the lower to middle
50s...with 40s in higher elevations...around 40 southern
Adirondacks. The front tracks through Sunday night and early Monday
with deep cold advection spreading across our region. Highs Monday
in the lower to middle 30s...with upper 20s in the southern Adirondacks
and southern Green Mountains. Cold advection continues Tuesday with
highs in the 20s...upper teens in the southern Adirondacks. There
could be lake effect snow bands Monday into Tuesday but the inland
extent is in question.
Aviation /12z Wednesday through Sunday/...
an upper level disturbance tracking through the region will bring
periods of broken ceilings above 3000 feet through the day. There
could be some flurries this morning so will put vcsh for a few hours
at kalb...kpsf...and kgfl. At the surface...high pressure will
build in. Scattered variable broken ceilings above 3000 feet should
continue through tonight mainly at kalb...kpsf and kgfl but just
scattered at kpou.
Winds will be light to calm through the early morning hours becoming
westerly during the late morning and increasing to 6 to 10 knots.
Some gusts into the teens are expected at kalb and kpsf from late
morning through the middle afternoon...and should continue into the
evening. Winds should decrease to 5 knots or less later this evening
and continue through the night.
Thursday night: low operational impact. Slight chance of shsn.
Friday: moderate operational impact. Chance of rain showers...shsn.
Friday night: moderate operational impact. Chance of rain showers...shsn.
Saturday: moderate operational impact. Chance of rain showers...ra.
Saturday night: high operational impact. Likely rain.
Sunday: high operational impact. Likely rain.
lake effect snowbands...and scattered snow showers will be
possible today and tonight...with maximum total liquid equivalent
generally remaining under one quarter of an inch...which would be
across the western Adirondacks.
Otherwise...through tonight...temperatures will continue to be below
normal and ice will continue to form and thicken on area
rivers...streams and particularly lakes.
A moderating trend in temperatures is likely Thursday into Friday...with a
frontal boundary bringing some showers to close the work week.
Some snow melt is likely this weekend. Also...a storm system
moving along a frontal boundary may bring significant precipitation to the
forecast area Sat night into Sunday with even milder temperatures. This
will continue to be monitored for the upcoming weekend for the
possibility of some Hydro issues.
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.
New York...Lake effect Snow Advisory from 3 PM this afternoon to 6 am EST
Thursday for nyz032-033.