Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
147 PM EDT Thu Oct 20 2016
a storm developing across the central Mississippi River valley
combining with a coastal storm will set the stage for an active
period of weather across the region today and through the weekend.
Much needed rainfall is in the forecast, to be followed by gusty
winds and much cooler temperatures for the weekend. Temperatures
may be cool enough for some snow, mainly across the higher
Near term /until 6 PM this evening/...
much needed rainfall moving across the local area. Have made some
adjustments based on regional radar, trends and latest guidance.
Have initial batch of rain covering most of the forecast with
isentropic lift occurring just ahead of an along an inverted
surface trough approaching from near the New York/PA border. Have had a
couple lightning strikes occur with the stronger returns so have
maintained a slight chance thunder with this batch as it moves
Also had to adjust temperatures, where is raining its cooler than
expected with slight warmer readings across the far southeastern
portion of the forecast area. Looking at a wide range of highs
from around 50s in portion of the western Adirondacks to the mid
60s in the Mid Hudson valley and across northwestern Connecticut.
Rain should tend to decrease in coverage this afternoon across
much of the area, as the boundary sets up to the west of the
region, with the exception of northern Herkimer and Hamilton
counties where rain should persist closer to the boundary.
As the day concludes, the best forcing with respect to low level
jet/warm advection and surface frontal convergence are expected to
line up across portions of the Adirondacks and western Mohawk
Valley. This would suggest pops would be the highest across these
areas with diminishing pops back to chance or slight chance for
the remainder of the region (either light showers and/or pockets
of drizzle). Under a cloudy sky, temperatures today should climb
into the low-mid 60s for Hudson River valley locations including
Litchfield County and 50s elsewhere.
Short term /6 PM this evening through Saturday night/...
much needed rainfall to be followed by brisk and cooler
temperatures with some snow across the higher terrain this
Tonight into Friday morning, NCEP model suite is in good agreement
with the best fgen forcing, low level convergence and upper jet
support to retrograde westward across central and western New York.
Meanwhile, we continue to watch developments across the Bahamas as
the latest guidance suggests what, if any development, should
remain far enough offshore to limit its direct impacts. Yet its
residual impacts will be as the upper trough amplifies it will
capture portions of this system to assist with deepening the
surface low across New England through Sunday. So this will result
in a period of rain/showers with the best potential for moderate
to heavy rainfall mainly to the west and northwest of Albany
through Saturday. See the hydrology section below for additional
details on quantitative precipitation forecast and potential impacts. So clouds and relatively
mild conditions tonight through most of Friday night.
Cold advection quickly unfolds Saturday morning as the trough
evolves from negative tilted to cut off upper low as it
transverses the region from south to north. Area of deformation
precipitation will move across the region from south to north
through the day as h850 temperatures drop back below 0c. Some of
the higher terrain may see some wet snow mix in from time to time,
especially Saturday night where some minor accumulations are
possible. Furthermore, westerly winds too will be on the increase
as tight pressure gradient and mixing layer heights tap into the
20-30kt range. Temperatures will likely fall through the day and
wind chills down into the 20s and 30s.
Overnight Saturday, the upper low and deformation axis lift
further northward with gradient improvements to the weather.
However, winds will remain an issue and some lake effect activity
along with any waves within the cyclonic flow regime to keep
chance pops for rain/snow showers. Temperatures should fall back down
into the 30s across the entire region.
Long term /Sunday through Wednesday/...
Wind Advisory possible for Sunday. Light snow accumulations possible
across higher elevations Sunday and Monday.
For Sunday, deep low pressure over the Canadian Maritimes will
continue to produce a cold cyclonic flow across the area with windy
conditions expected. Model guidance indicates that a Wind Advisory
may be necessary as winds could gust to around 50 miles per hour. Expect partly
sunny skies and windy with highs in the 40s hill towns to 50s
For Sunday night into Monday, a cold front is forecast to cross the
area. Some model differences as 00z GFS produces a wave on the front
and slows it down while 00z Euro is much more progressive. All
models and GFS ensembles have the front through our area by 18z
Monday. For now chance/slight chance pops with light precipitation
amounts expected of a quarter inch liquid or less. Precipitation
looks to be mainly rain as wet bulb zero height climbs to nearly
5kft mean sea level. Monday should become partly sunny and with a cold breeze
developing. There is a chance for a few light rain or snow showers
during the afternoon with strong cold advection. Lows in the 30s to
around 40 and highs in the upper 40s to upper 50s.
For Tuesday and Wednesday, a high pressure ridge extending from
eastern Canada to the Ohio Valley should provide mainly fair and
cold weather. There is a chance for some snow flurries across the
higher elevations of the Adirondacks and southern Vermont. Lows in
the 20s to around freezing and highs in the 40s to around 50.
Aviation /18z Thursday through Tuesday/...
steady rain falling from kalb-kgfl early this afternoon, with
rain shield likely remaining north of kpou, and kpsf right on the
northern edge. Will continue to mention IFR/MVFR vsby at
kalb/kgfl from 18z-20z where it is raining, and limit kpsf to MVFR
vsby with only occasional light rain through 21z. VFR conditions
should persist at kpou through this afternoon. Rain will taper off
to scattered showers after around 20z, so will only mention vcsh
Southerly low level flow will bring low stratus clouds and some br
developing during the evening to overnight hours at all the taf
sites. MVFR conditions appear likely to develop, with possible IFR
as well. Best chance for IFR conditions will be at higher
elevation site kpsf. Conditions should improve somewhat by late
Friday morning, as the region gets into a warm sector due to
amplifying flow aloft. Still plenty of clouds expected but
conditions should improve to MVFR range.
Winds will be east-southeast around 5-10 kt with some higher gusts
at kpsf this afternoon. Winds will become southerly on Friday at
5-10 kt. Low level wind shear will begin early Friday morning lasting well into
Friday, as a low level southerly jet around 40 kt moves in.
Friday night: high operational impact. Breezy definite rain.
Saturday: moderate operational impact. Windy. Likely rain.
Saturday night: moderate operational impact. Breezy chance of rain showers.
Sunday: low operational impact. Breezy slight chance of rain showers.
Sunday night: low operational impact. Slight chance of rain showers.
Monday: moderate operational impact. Chance of rain showers.
Monday night: no operational impact. No sig weather.
Tuesday: no operational impact. No sig weather.
minimal to no fire weather concerns as increasing moisture and
periods of rain/showers are in the forecast for the remainder of
the week into the weekend.
latest quantitative precipitation forecast suggests 3-5 inches of rain for portions of the
Adirondacks and western Mohawk Valley with generally 1-2 inches
elsewhere through Saturday night. Despite these higher values, the
latest mmefs points toward within bank rises to no more than half
to three-quarter bank full through the weekend (especially along
the western Mohawk River into the adirondacks). So main Stem
rivers and streams should remain below flood stage at this time.
Per the latest US drought monitor, conditions have worsen across
portions of the area. Precipitation departures this calendar year
are 5 to 15 inches below normal, with the greatest departures
across southeastern parts of the hsa. As a result, streamflow and
ground water levels have been running well below normal.
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.