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fxus61 kaly 202333 
afdaly

Area forecast discussion
National Weather Service Albany New York
633 PM EST Mon Feb 20 2017

Synopsis...
high pressure will build across the region tonight, exiting
east on Tuesday. A weak mid level disturbance approaching from
the west will bring chances for light mixed wintry precipitation
Tuesday evening through Tuesday night. Mild conditions are
expected for the remainder of the week.

&&

Near term /until 6 am Tuesday morning/...
as of 630 PM EST...ridging continues with some cirrus/cs spilling
over the ridge axis across central and western New York. Minor tweaks
to the temperatures/dewpoints.

High pressure building south out of Canada will be centered
over our region tonight. Calm winds and a clear sky should help
temperatures fall to the teens to around 20f with some single
numbers in northern areas.

&&

Short term /6 am Tuesday morning through Thursday/...
low level ridging builds east as an upper ridge axis centers
itself over our region. Boundary layer temperatures warm
considerably and boundary layer winds shift to the west. Low
level winds become light south and some high thin clouds spread
across our region through the day. It could take some time for
low level inversions to mix out with the relatively light winds
through the boundary layer but the sunshine and warm advection
should help temperatures to reach highs well into the 40s in
many areas...maybe near 50 southern areas and lower 40s
northern areas.

Fast moving northern stream energy approaches Tuesday afternoon
and crosses our region Tuesday night. Some cooling could occur
Tuesday evening before the clouds thicken and lower later in the
evening and through the rest of the night. Coverage of
precipitation will increase later in the evening and though the
night but dynamics, forcing and isentropic lift as well as deep
moisture will be lacking. So, chances for rain in central and
southern areas with temperatures above freezing. A chance for a
mix including spotty freezing rain in northern areas, parts of
southern Vermont and parts of the Berkshires. Because of the
questionable coverage and just chances for precipitation, no
winter weather advisories being considered but if coverage of
freezing rain is expected to be greater with newer guidance
available tonight and Tuesday, advisories may need to be
considered.

The quick movement to the system should result in clearing of
the low level cloudiness but some of the thin mid and high
clouds could linger through some of Wednesday. Boundary layer
temperatures continue to warm and boundary layer winds become
west to southwest with surface winds form the south. This should
support temperatures warming into the lower to mid 50s but
around 50 northern areas.

By Thursday, there are some hints that a weak cold front could
sink south of the Canadian border with some isolated to
scattered showers but there is a lot of disagreement in
guidance. Based on the upper ridging expected to be over our
region, siding with the warmer and dryer scenario. Still, a mix
of mid and high clouds likely but sunshine and warm advection
should still help temperatures to get to the mid 50s to lower
60s but lower 50s northern areas.

&&

Long term /Thursday night through Monday/...
an increasingly active period of weather is expected for the long
term forecast as potent Pacific jet comes ashore and helps carve out
a sharp trough over the center of our nation.

We begin this long term with a fast moving wave across Canada with
its attending frontal boundary becoming nearly quasi-stationary
across the northeast corridor. This would favor more in the way of
cloud coverage but low confidence precipitation forecast as we will
keep pops into the slight chance range. Lows will mainly fall into
the 30s to some lower 40s.

Then as the aforementioned Pacific jet interacts with increasing
baroclinic zone over the plains and Great Lakes, strengthening storm
evolves across the mid-Mississippi River valley through Friday. While
a potential blizzard may develop over the center of the nation,
downstream impacts will be the approach and eventual passage of a
warm front across our corridor. Elevated area of showers/light rain
may develop and move across the region through the day with the best
potential along and north of i90. Temperatures moderate through the
40s into the lower half of the 50s.

Then even milder and increasingly moist flow develops as h850
temperatures moderate above +10c Friday night. So a relatively
milder night with lows generally into the 40s along with the chance
for light rain/drizzle or showers.

NCEP model suite and international guidance are in rather good
agreement with taking the potent storm tracking across the Great
Lakes and taking a sharp cold front across the area Saturday
afternoon. Impressive low level jet, mid level jet and higher
moisture content and instability warrant the chance inclusion for
thunder into the forecast. Based on the current information, it
would appear a convective line races across the region.

Then a sharp drop in temperatures expected for this last weekend of
February as h850 temperatures fall back below -10c through Sunday.
So we transition back to snow showers and some lake effect snow
downwind of Lake Ontario. Temperatures settle back to the 20s and
lower 30s for highs on Sunday.

&&

Aviation /00z Tuesday through Saturday/...
VFR conditions forecast through the taf period /00z Wednesday/.
Mainly clear skies forecast for the rest of tonight, with high
and then mid clouds increasing through Tuesday morning.
Ceilings lower late Tuesday morning to the 10-15kft mean sea level range.

Winds will be diminishing to 10 kt or less in the evening.
Winds will be nearly calm overnight. Winds will increase Tuesday
morning from the south to 5 to 10 kts.

Outlook...

Tuesday night: moderate operational impact. Chance of rain.
Wednesday: no operational impact. No sig weather.
Wednesday night: no operational impact. No sig weather.
Thursday: no operational impact. No sig weather.
Thursday night: low operational impact. Slight chance of rain showers.
Friday: moderate operational impact. Chance of rain showers.
Friday night: moderate operational impact. Chance of rain showers.
Saturday: high operational impact. Likely rain showers...tsra.

&&

Hydrology...
no widespread Hydro problems are expected into the middle of
this week with light precipitation forecast and overnight
temperatures falling below freezing most nights.

Milder temperatures are expected for later this week. This will
cause snowmelt. Also, a large storm system may bring a moderate
to heavy rainfall on Saturday. The long term meteorological
model ensemble river forecasts /mmefs/ suggest that significant
river rises along with some flooding is possible Saturday into
Sunday due to the combination of snow melt and locally heavy
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.

&&

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

&&

$$
Synopsis...NAS
near term...bgm/NAS
short term...NAS

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