Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
951 am EST Thursday Dec 5 2013
a southerly flow will usher in a very mild and moist air mass today.
Shower coverage will increase as a cold front...approaching from
the northwest...moving into the area this evening. A wave forming
along the cold front will bring a period of steady precipitation
tonight. This will fall as rain from the capital district south
but as a winter mix further north with minor accumulations
possible over the Adirondacks by early Friday. Another
disturbance...moving along a stalled out front to our south will
likely bring another round of precipitation...mainly as snow to
our region Friday night.
Near term /until 6 PM this evening/...
as of 950 am EST...local and regional radars showing most of the
region precipitation-free late this morning...with just some patchy
drizzle and scattered showers working into portions of the
Adirondacks. So will lower probability of precipitation until afternoon...when addi tonal
moisture approaches associated with a cold front moving in from
the west. Will then gradually increase probability of precipitation from northwest to
southeast across the area. Lowered maximum temperatures a bit from the
previous forecast due to expected low stratus clouds and drizzle
from a marine influence...as low level winds remain southerly. It
will still be a mild day ahead of the cold front despite cloud
cover...with highs in the upper 40s to middle 50s across the area.
Short term /6 PM this evening through Saturday night/...
the aforementioned cold front will steadily March into areas north
and west of the capital district this evening...cross the capital
region around midnight...and work through our southeastern zones
during the overnight hours.
A potent disturbance seen on our water vapor loop over the
southern Ohio Valley...will ride along the front tonight bringing
a steady band of overrunning precipitation with it. Thermal
profiles from most models indicate liquid rain will fall through
tonight into much of the day tomorrow from the capital region
south and east. However...north and west of the capital
region...enough low level cold air looks to change the rain to a
brief period of sleet and perhaps freezing rain...and eventually
snow by Friday morning. Any accumulations of snow will be
generally less than an inch and confined to the Adirondacks.
Temperatures will be too warm from frozen precipitation elsewhere.
We should get a brief break in precipitation by midday Friday
between systems...although it looks to remain mostly cloudy.
Another disturbance...located in SW Texas will ride along the
stalled out front to our south Friday night...which will allow
precipitation to quickly re-develop late in the day. By this time...it
looks as if enough cold air will be in place...not only at the
surface...but throughout entire column to support snow...or snow
mixed with a little sleet. The big question is how much snow will
fall. The best forcing...and low level convergence looks to be
along a strip near the Interstate-84 where over a quarter of an
inch of precipitation could fall. Further north...amounts will
lighter...but still enough to produce accumulating snow as snow to
liquid ratios will be higher.
Our latest thinking Friday night is for generally a 1-3 inch
snowfall...especially south of Albany...but well under an inch
for areas north and west.
Highs Friday will be held to the lower to middle 40s from the capital
region southward...30s further north with temperatures dropping late in
the day into the evening.
Saturday will feature a northwesterly flow regime and colder air
filtering into the region. There could be a Minor Lake response
with some lake effect snow showers across the western Mohawk
Valley and southwestern Adirondacks. However...high pressure is
forecast to build in fairly quickly by Saturday night which should
end any lake effect activity. Cold and tranquil weather is
expected Saturday night.
Long term /Sunday through Wednesday/...
a tranquil end to the weekend is expected as high pressure begins to
retreat to our northeast. Our attention remains with the Pacific
coastline waves as they track southward into the base of the
trough...then across The Four Corners region and out onto the
plains. Ample Gulf of Mexico moisture entrainment is expected to
advect northward late Sunday into Sunday night. As this
time...thermal profiles and thickness schemes suggest most of the
precipitation Sunday night will fall in the form of snow. Quantitative precipitation forecast
averages from the 00z suite of model diagnostics range from one
third to one half of an inch. A simple ratio applied of 10:1 would
yield an average 3-5 inches. However...this does not account for
lift within the dendritic ice growth region nor mesoscale bands that
could develop. We will continue to highlight in the severe weather potential statement this
Warmer air does arrive early Monday morning as we will watch a quick
transition from south to north from snow to a period of
sleet/freezing rain then mainly rain /or rain showers/ for valley
locations toward midday. Dry slot is expected to move across the
County warning forecast area during the afternoon with a significant reduction in
precipitation coverage and may even allow for some breaks in the
Then the cold front is forecast to move across the area Monday night
with a large thermal profile change from h850 temperatures averaging around
0c Monday to around -16c late Tuesday into Wednesday. This will be
sure to increase the potential for lake effect snow downwind of the
lakes with boundary layer wind profiles suggesting mainly the dacks.
Temperatures through the period will start out near to above normal
then quickly drop back to below normal during the middle week period.
Aviation /15z Thursday through Monday/...
flight restrictions into MVFR flight categories are fast advecting
into the region per upstream metars and 11u-3.9u enhanced satellite
imagery. Just a little further upstream are IFR conditions which
should spread into the region toward sunrise.
Furthermore...expectations are for light showers and/or drizzle to
evolve as frontal boundary becomes a bit more defined through the
Low level wind shear appears to be on the increase per the latest bufr forecast
sounding profiles as we will introduce this into all tafs late in
the afternoon hours and continue into the evening.
tonight to friday: high operational impact. Likely rain.
Friday night: high operational impact. Chance of rain...sn...sleet.
Saturday to sunday: no operational impact. No sig weather.
Sunday night: high operational impact. Likely snow.
Monday: high operational impact. Likely rain...fzra...sleet.
no Hydro related concerns are expected over the next 5 days.
Tonight into Friday...as a strong cold front gradually pushes
through our region...a wave of low pressure will likely produce a
bit more significant rainfall across mainly our central and southern
areas where one half to one inch of rain could fall. These rainfall
amounts would be enough to produce some within bank rises on main
Stem rivers...however no flooding is expected. Further north and EST
of the capital district...rain will switch to a wintry mix with
little or rises expected on watersheds.
It will then turn colder after this system finally pushes through
Friday night with any additional precipitation falling as mainly
snow. 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...possibly ending as some rain.
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.