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afdaly

Area forecast discussion
National Weather Service Albany New York
1035 PM EST Tue Nov 21 2017

Synopsis...
a cold front will cross the region later tonight through
Wednesday, with some light precipitation. Brisk and cooler weather
returns Wednesday afternoon. A ridge of high pressure and cold
weather is expected Wednesday night through Thanksgiving with clouds
expected during Thanksgiving afternoon.

&&

Near term /through Wednesday/...
as of 1035 PM...approaching cold front has passed through
Niagara Falls, New York. Clouds have thinned over most of the area
with the cloud shield associated with the cold front now
covering the southwestern Adirondacks. Where the winds have
decoupled from the surface, temperatures have fallen into the
20s and 30s. Temperatures likely to rise in these locations as
clouds increase. Expect clouds to continue increase tonight as
cold front approaches from the northwest. Based on radar, rain
showers with cold front now over Thousand Islands with some
showers possible around midnight over northern Herkimer and
Hamilton counties. Slow southeast progression of showers
overnight.

Previous...
thereafter, shower potential increases and per profiles, a
rain/snow mixture is expected as cold advection gets underway
with the frontal passage. At this time, the low pressure area
developing along the northeast Gulf of Mexico coast is expected
to pass just to our east with limited impacts to our southeast
zones. In addition, the timing of the frontal passage is a bit
faster so the best potential for wet conditions appear to be
Wednesday morning. Where snow does occur, seems accumulations
mainly 1-2 inches to the west of the Hudson and across the
higher terrain. Then drier and brisk conditions advect into the
region through the afternoon hours as main upper trough axis
slides quickly across the area through the early afternoon
hours. Some Minor Lake response is possible but inland
penetration and inversion heights look rather unfavorable to
limit impacts. Temperatures through Wednesday should see highs
early in the day with near to falling temperatures in the
afternoon hours.

&&

Short term /Wednesday night through Friday/...
fair weather for the Thanksgiving day Holiday.

High pressure builds briefly into the region from the Ohio
Valley Wednesday night with tranquil weather conditions under
mainly clear skies. Clouds do increase on Thanksgiving as a
broad trough and mid level moisture track through the region.
However, seems the lower levels of the troposphere remain dry
enough to withhold the mention of pops/wx for the balance of the
daylight hours. Chances for any snow showers are expected to be
limited to portions of the western Adirondacks Thanksgiving
night with seasonable low temperatures as winds shift to the
southwest with Minor Lake influences expected.

Another cold front from north-central Canada brushes by just to
the north of i90 overnight which will assist with some Lake
Ontario response but quite minor impacts expected. Then another
warm front approaches for Friday with dry and seasonable
temperatures.

&&

Long term /Friday night through Tuesday/...
quiet weather starts the extended period with a 1020 high positioned
off the New England coast and southwesterly flow in place over
eastern New York/western New England. While Saturday should be fairly
seasonable in the low - mid 40s (30s in the
dacks/Catskills/greens/berkshires), clouds will quickly thicken
ahead of a rather moisture starved advancing cold front. Most
guidance suggest showers (mainly rain...perhaps rain/snow in
elevations of the dacks) reaching areas north and west of the
capital district during the afternoon but weakening and even drying
out as they progress south and east. To account for the weak forcing
associated with this front, have the highest pops of 40 - 50% in the
dacks and decreasing down to low chance pops south and east of the
capital district.

The main baroclinic zone and wind shift looks to be delayed behind
this band of light showers until around 06z Sunday (still some model
differences on exact timing). At this time, westerly upper level
flow veers to the northwest and the true cold air advection begins.
H850 isotherms quickly fall to -4 to -8c with h850 winds increasing
to 30-40kts. Strong northwest flow and cold air advection continues
into the daytime Sunday as the upper level neutrally tiled trough
progresses through the region. This should lead to a chilly and
breezy day as h850 isotherms bottom out near -8 to -12c during the
Day. Lake effect snow showers are possible as well given the still
warm lakes and this cold air moving into the northeast.

The main trough axis should exit by 00z Monday but a secondary piece
of energy potentially riding along the backside of the trough will
need to be monitored as it could introduce a threat for light snow
Sunday night. At this time, accounted for this threat with slight
chance pops mainly north and west of the capital district.

Pleasant weather follows for the work week as high pressure
and ridging builds back in from the southeast U.S Monday -
Wednesday.

&&

Aviation /03z Wednesday through Sunday/...
mainly just passing high level clouds through this evening.
Then, clouds will increase late tonight into early Wednesday
morning ahead of a cold front approaching from the Great Lakes.
Cigs will gradually lower from VFR to MVFR during this time,
with mainly scattered rain showers expected to develop ahead of
and along the cold front. Generally p6sm in light rain or rain
showers with MVFR ceilings for a few hours on Wednesday except
kpsf where IFR expected.

Winds tonight will be southerly, with speeds decreasing to
around 5-10 kt. Winds on Wednesday will shift to the northwest
by late morning behind the cold front.

Outlook...

Wednesday night: no operational impact. No sig weather.
Thanksgiving day: no operational impact. No sig weather.
Thursday night: no operational impact. No sig weather.
Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: moderate operational impact. Chance of rain.
Saturday night: low operational impact. Slight chance of rain showers.
Sunday: moderate operational impact. Chance of rain showers.

&&

Fire weather...
south to southwest winds 10 to 20 mph with gusts up to around
30 mph at times this afternoon with minimum relative humidity
values in the 30s.

Fair and mild today ahead of an approaching cold front. The front
will sweep across the region late tonight into Wednesday bringing
some snow and rain showers to the area. A more seasonable air mass
will be ushered back in with mainly fair weather then expected
through Friday.

&&

Hydrology...
no hydrologic problems are expected this week.

Fair and milder weather into this evening with some rain and
snow showers late tonight into Wednesday as a cold front crosses
the region. Quantitative precipitation forecast amounts are expected to be light with about a
quarter of an inch across the western Adirondacks with lesser
amounts elsewhere.

With the passage of the cold front a more seasonable air mass
will be ushered back in with mainly fair weather then expected
through Friday.

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.

&&

Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...sand
near term...snd/bgm
short term...bgm

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