Scientific Forecaster Discussion
fxus61 kaly 270543
Area forecast discussion
National Weather Service Albany New York
1243 am EST Mon Feb 27 2017
high pressure will briefly build in from the mid Atlantic
region tonight into Monday with moderating temperatures back to
above normal readings. The next chance of rain and snow showers
will be Monday night into Tuesday with a warm front and low
pressure moving into the Midwest.
Near term /until 6 am this morning/...
as of 1220 am EST, low level ridging across the area has allowed
temperatures to quickly drop into the teens and low 20s early
this morning. However, over the past hour, temperatures have
begun creeping up as mid-level clouds and a nose of warm air
moves into the region. We should see temperatures slowly
climb/remain steady through the remainder of the overnight
period as clouds increase. So have freshened up hourly temps and
sky cover to reflect most recent obs. Otherwise, forecast
remains on track.
Prev disc, mid level clouds currently spreading east across the
eastern Great Lakes region should begin to move across the
southern Adirondacks after midnight, in association with
developing warm advection. Most near-term model guidance
suggests at least patchy clouds across these areas, with less to
the south of the Mohawk River.
Boundary layer winds shift more west to southwest but not all
the the boundary layer winds are expected to mix to the surface.
There could be some channeling of winds in the Hudson Valley
later tonight as surface winds trend to south. However,
sheltered areas should see light winds through much of the
The combination of some clouds, and backing winds into more of
the south/southwest should allow temps to actually rise after
midnight across some northern areas, and also possibly within
some north/south valleys, so early lows in the teens and 20s may
be attained before midnight. In some other areas, localized
decoupling could still allow for temps to drop into the upper
teens and lower 20s after midnight, although even in any of
these areas, temps may start rising before daybreak as warm
Short term /6 am this morning through Wednesday/...
strong west to southwest boundary flow and slowly warming
boundary layer temperatures will help our surface temperatures
to warm through the day Monday. Some upper energy is expected to
track across southern areas but there are very little dynamics
or moisture and there may only be some mixed mid and high clouds
in southern areas Monday.
Low level winds could be a bit breezy Monday afternoon and with
some downsloping along with warm advection and sunshine, highs
Monday in the 50s but lower to mid 40s northern areas.
There are considerable disagreements in guidance in the Tuesday
through Wednesday time frame. Some guidance has upper energy
tracking out of The Rockies with enough moisture and upper
dynamics to support some coverage of clouds and showers Tuesday.
Other guidance suggests just mid and high clouds Tuesday and
delays any upper energy and moisture until Tuesday night. Based
on the continued southwest boundary layer flow, even if upper
energy arrives sooner, moisture should be relatively limited
even if there are more clouds than sun.
So, warm advection and downslope flow should result in
temperatures warmer than coolest temperature guidance but maybe
not quite as warm as warmest guidance, depending on coverage of
clouds and showers. Highs Tuesday in the 50s but upper 40s
Stronger upper energy and an associated cold front approach
through the day Wednesday. Some question as to how quickly
moisture and upper dynamics approach, which will determine how
much warming we will see Wednesday. Some intervals of clouds and
isolated to scattered showers Tuesday night but not much of a
strong low level forcing signal in guidance. Some isentropic
lift could contribute to development of more widespread clouds
Wednesday could be quite warm if the southwest boundary layer
flow maximizes downslope. There are indications of some surface
based instability ahead of an approaching strong cold front as
well as some hints of an elevated mixed layer. Indicating
isolated thunderstorms Wednesday but too early to evaluate the
potential strength of the convection.
The character of the upper dynamics and low level cold front
Wednesday are not as strong as what we saw yesterday. However we
have days to watch it and the forecast evolution could change.
Highs Wednesday in the 60s but mid to upper 50s higher terrain.
Long term /Wednesday night through Sunday/...
active weather will persist through much of the long term period,
with a transition from zonal flow to a broad trough at upper levels,
and much colder temperatures by later this week. Then, potentially
transitioning back to a more zonal pattern by later next weekend.
A strong cold front will track across the region Wednesday night,
and may be preceded and/or accompanied by showers and perhaps
isolated thunderstorms, as there are subtle hints of steep mid level
lapse rates/instability ahead of the front. Then, behind the front,
we will transition to a much colder air mass by Thursday morning.
Temperatures may fall through the day Thursday with the high
temperature likely occurring at midnight with perhaps another brief
rise in temps during the midday hours. Temperatures will start out in
the 40s and 50s Wed night, perhaps even warmer in some areas, but
should fall into the 30s to lower 40s by daybreak Thursday, and then
into the low teens to low 20s by Thursday night. As cold air invades
the region behind the front, any lingering rainfall is expected to
change over to snow showers/flurries on Thursday, with perhaps up to
a couple inches of snow accumulation in the Adirondacks.
Depending on how strong the parent low to our north becomes, there
could be strong winds across the region within the cold air
advective regime Thursday, possibly reaching advisory levels in some
areas. Will address this potential in the hwoaly.
Another low pressure system passes by the region to the south late
Thursday night into Friday with a slight chance for light snow,
mainly for areas close to the I-84 corridor. Temperatures will be
seasonable with afternoon highs reaching the low 20s in the high
terrain and the mid to upper 30s across the valley locations. The
core of the upper trough will be over the capital district Friday
night where we could see temperatures plummet to near zero in the
Adirondacks and into the single digits/teens elsewhere. Brisk winds
could lead to wind chills dropping into the -10 to -20 degree range
across the southern Adirondacks, and 5 above to 10 below elsewhere.
Lake effect snow could be possible on Friday night/Saturday for the
areas downwind of Lake Ontario as cold westerly/northwesterly flow
Another system approaching from the Great Lakes could bring some
clouds and light snow or snow showers to at least northern areas for
Saturday night into Sunday morning, as a warm front associated with
this weak system passes through. Expect Saturday highs mainly in the
20s and 30s, with Sunday highs warming into the 30s and 40s.
Overnight lows Sat nt/sun am should mainly be in the teens and
Aviation /06z Monday through Friday/...
high pressure continues to ridge in from the mid Atlantic states
this morning. It will continue to drift offshore into the Atlantic
this afternoon with VFR conditions prevailing for the taf sites.
Warm advection continues this morning with the sfc high building in
from the south and the mid level flow becoming zonal. Few-sct mid
level or high clouds will be around this morning into the afternoon,
but overall the skies will be mostly clear. The clouds will
increase after 00z/Tuesday with cigs in the 7-10 kft above ground level with a frontal
boundary to the north of the region, and a warm front slowly lifting
northward from the Ohio Valley and mid Atlantic region.
The winds will be light from the south at 4-8kts at kalb/kpsf/kgfl
and be calm at kpou early this morning. A low-level wind shear
group was maintained at kpou with westerly winds at the 2 kft above ground level of
30 kts. The group was removed at 13z, as the sfc winds will pick up
there. The winds will increase from south to southwest at 10-15 kts
by the late morning and gust to 20-25 kts with slightly higher gusts
at kpsf. The winds will quickly subside by sunset or around 23z to 5
kts or less for the overnight period.
Monday night: low operational impact. Slight chance of shsn.
Tuesday: moderate operational impact. Chance of rain showers...shsn.
Tuesday night: moderate operational impact. Chance of rain showers.
Wednesday: high operational impact. Likely rain showers...tsra.
Wednesday night: high operational impact. Breezy likely rain showers...tsra.
Thursday: moderate operational impact. Windy with gusts to 35.0
slight chance of rain showers.
Thursday night: no operational impact. No sig weather.
Friday: slight chance of snow.
Troy is inching toward minor flood stage and may or may not
touch minor flood stage this afternoon and evening. Flood
Warning in effect there for that possibility.
Drier and much colder air over our region through tonight. Then,
dry weather continues through Tuesday but temperatures are
expected to warm Monday through Wednesday and snow melt should
occur into the middle of next week. The next chance of
widespread rainfall will be Tuesday night through Wednesday.
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.