Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kaly 230227 
afdaly

Area forecast discussion
National Weather Service Albany New York
927 PM EST Fri Nov 22 2019

Synopsis...
a strong cold front has moved through the region today with
quickly cooling temperatures being observed. Precipitation for
the most part has tapered off with the possibility of some rain
and snow showers across the region through the evening hours
before drier air moves into the region. Gusty west to northwest
winds will continue through the evening hours before weakening
overnight. Quieter weather is in store for much of Saturday
before a strong system tracks to our south and could bring a
wintry mix of weather to parts of far southern New York, western
Connecticut and western Massachusetts through Sunday morning.
Quieter weather then returns for the first half of the work week
before another strong system approaches the region.

&&

Near term /through Saturday night/...
some clouds in our region off Lake Ontario and the moisture
layer is fairly shallow. So, there are no snow showers extending
into our region. The cloud layer is anchored by a bit of an
inversion aloft, so the clouds could be rather slow to erode
through the night. However, gradual erosion is expected,along
with diminishing winds. Some minor adjustments to temperatures,
winds and sky cover through the night based on current data and
trends. Previous afd has a few more details and is below...

The gusty winds have materialized on the backside of the cold
front with strong mixing (which has also created the weak
instability across the region). Due to the degree of cold air
advection over the next 6-8 hours, it'll take some time for the
winds to diminish as we should continue to mix to about 900 mb
through almost midnight. The winds will, however, wane heading
into the late evening hours as the core of stronger winds begins
to exit the region.

Temperatures tonight will be quite a bit cooler than those
observed last night thanks to the strong cold air advection.
Overnight lows ranging from the upper teens in the southern
Adirondacks to the mid 20s across southern New York will be
seen. While these temperatures aren't as cold as the ones
observed recently, they should still run about five degrees
below normal. Any of the lingering snow showers mentioned above
will dissipate through the evening and overnight hours as the
main moisture axis shifts east and drier air quickly moves into
the region.

Mostly clear skies are on tap for Saturday with a weak and
transient surface high moving across the region. As the high
begins to shift east of the region Saturday afternoon, winds
will begin to shift back to the south/southwest. With the
abundant sunshine on Saturday, we should see temperatures warm
into the lower to mid 40s. An upper level trough and a weak
surface reflection will move into the forecast area around
midnight Saturday night which will bring the next chance of
precipitation to the region. Thermodynamic profiles get a little
bit tricky, especially across western Connecticut and southern
New York where profiles support the potential for some light
freezing rain that could mix with snow. There is still a bit of
uncertainty to how the Thermo profiles will play out and just a
degree or two in the low levels could trend the profiles to more
snow or even to rain. With the surface low tracking well to our
south, precipitation totals will be less than a tenth of an inch
so the overall impacts with this system are expected to be quite
minor.

&&

Short term /Sunday/...
mixed precipitation associated with the low pressure system
will continue into the daylight hours on Sunday but will
gradually transition to rain as we begin to warm after sunrise.
It'll take some time for the rainfall to end on Sunday as
moisture wraps around the surface low and the upper level trough
begins to take on a little bit of a negative tilt. Towards the
end of the event, we could see some of the rain mix with or
change to snow but the window for any wintry precipitation looks
fairly small given how quickly the surface low will track east
of the region. Calmer weather then situates across the mid-
Atlantic as surface ridging begins to build across the region
with some mid- level height rises.

&&

Long term /Sunday night through Friday/...
both Monday and Tuesday look to be very nice late November days
across the region with temperatures warming back above normal by
Tuesday afternoon with plenty of filtered sunlight. A deepening
upper level trough over the central US will help to amplify
upper level ridging across the East Coast which will ultimately
lead to the quieter and warmer weather for the beginning of the
work week. That changes, however, as we head into Wednesday as
we will a deepening surface low track across the St. Lawrence
Valley in northern New York. While much of the moisture will
remain north of the forecast area, the chances for some mixed
precipitation will be possible near the Adirondacks as some
warmer air could overrun some of the below freezing temperatures
at the surface. Based on the latest guidance, any freezing
rain/sleet would be fairly short-lived given the degree of warm
air advection and the lack of northerly winds to defeat the
self termination process associated with freezing rain.

The biggest concern with this system on Wednesday will be the
potential for strong to possibly damaging wind gusts. An
impressive pressure gradient will develop across the region
throughout the day on Wednesday with wind gusts in the 25 to 40
mph range possible. Given how far out this storm system is,
there is remarkably good agreement amongst both the
deterministic and ensemble guidance as of 12z. Also, given the
lower spatial resolution associated with the global models the
aforementioned wind gusts could be a tad bit on the low side.
It'll be interesting to monitor this system in the coming days
since it could potentially impact those traveling before
Thanksgiving.

Thanksgiving day will be noticeably cooler as afternoon high
temperatures will struggle to warm into the lower 30s across the
Adirondacks to around 40 degrees across southern New York. It'll
also be quite blustery with wind gusts in the 25-40 mph range
continuing throughout the day. It won't be until after midnight
on Thursday that winds will really begin to weaken.

&&

Aviation /03z Saturday through Wednesday/...
flurries and sprinkles off Lake Ontario not quite making it to
the Hudson Valley and leaving out of tafs. Intervals of a
ceiling above 3000 feet will be predominant through the night
and become scattered around or after daybreak. VFR conditions
will continue through the day Saturday.

West to northwest winds at 10 to 15 kt with gusts to 30 kt will
diminish to under 10 kt by daybreak Saturday. West winds at
around 6 kt Saturday morning will shift to south and southwest
by afternoon.

Outlook...

Saturday night: moderate operational impact. Chance of snow.
Sunday: moderate operational impact. Likely rain...sn...sleet.
Sunday night: no operational impact. No sig weather.
Monday: no operational impact. No sig weather.
Monday night: no operational impact. No sig weather.
Tuesday: no operational impact. No sig weather.
Tuesday night: moderate operational impact. Chance of rain showers.
Wednesday: moderate operational impact. Breezy likely rain showers.

&&

Hydrology...
no widespread problems are expected on the main Stem rivers and
within the aly hsa through the middle of next week.

The precipitation from today will have little effect on the aly
hsa waterways.

A complex storm system may bring some rain, snow and or a wintry
mix Saturday night into Sunday with light to moderate amounts of
qpf, but their is still uncertainty in the track, evolution and
the amount of quantitative precipitation forecast with this system. The bottom line, there will
be minimal impacts or rises on the waterways.

For details on specific area rivers and lakes, including latest
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...none.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...btv
near term...NAS/btv

National Weather Service Glossary of Abbreviations