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Area forecast discussion 
National Weather Service Albany New York
950 am EST sun Mar 1 2015

Synopsis...
a low pressure system approaching from the Great Lakes and Ohio
Valley is expected to bring a light to moderate snowfall to our
region this afternoon through tonight. High pressure will build back
in late Monday into early Tuesday...before another storm system
approaches from the west. This system is expected to bring more
unsettled weather late Tuesday into Wednesday...including the
potential for a wintry mix of precipitation.

&&

Near term /through tonight/...
Winter Weather Advisory remains in place across Herkimer
County...the Mohawk and Schoharie valleys...eastern
Catskills...middle Hudson Valley...Taconics...Litchfield Hills...
Berkshires and southern Green Mountains starting at noontime.

As of 945 am EST...spotty light snow has reached as far north as
the capital region/Mohawk Valley/Saratoga region. The column is
still saturating with the isentropic lift ahead of short-wave in
the west/SW flow aloft...and the warm front near the Tennessee/Ohio Valley.
The 12z kaly sounding shows all the dry air below 750 hpa. Have
lowered temperatures about 3-4 degrees due to the colder temperatures in
place...and the onset of the snowfall. Locations in the middle Hudson
Valley/southeast Catskills/northwest CT we have increased the probability of precipitation due to the
radar trends. The best chance of light snow accums of a half an inch
or so prior to noon will be the southeast zones. By the early to middle
afternoon the virga will be less...and light snow will overspread
most of the forecast area.

The system is very progressive due to the fast-moving flow
pattern aloft and the upper level short wave being an open wave.
Steady snow should end a few hours before sunrise Monday.

We are still forecasting generally 3 to 6 inches within the current
advisory area...with 1 to 3 inches outside of the advisory area. The
GFS/ECMWF/ggem continue to be in generally good agreement with
regards to the quantitative precipitation forecast...with the NAM showing somewhat higher amounts as
it is indicating secondary cyclogenesis south of Long Island. As a
result...the NAM is also showing good potential for snow growth
across the southeast portion of our area...but the GFS is not as
robust. Keeping this potential in mind...we are thinking the best
potential for the higher end snow accumulations near 6 inches will
be over southern portions of Ulster and Dutchess counties in
New York...and southern Berkshire and Litchfield counties in western New
England. Will continue to use a 13 to 1 snow to liquid
ratio...although this could vary across the area.

Even though steady snow tapers off early Monday morning...a
northwest cyclonic flow will result in upslope snow showers across
the higher terrain to the west and east of the Hudson Valley

&&

Short term /Monday through Tuesday/...
low pressure will intensify as it tracks NE into the Canadian
Maritimes...while high pressure builds east into the Ohio Valley
during the day Monday. The pressure gradient between the high and
low will result in gusty northwest winds across our area. Despite
limited warming into the lower 30s in the Hudson Valley and even middle
30s south...the persistent wind will make it feel colder. Wind gusts
of 30-40 miles per hour will be likely...especially across the higher terrain
and favored west-east oriented valleys. Upslope snow showers will also
continue...mainly across the western Adirondacks and into southern
Green Mountains of Vermont. Minor accumulations of 1-3 inches will
be possible in a few spots within the most persistent snow showers.

By early Monday evening the flow starts to become more
anticyclonic...which should rapidly shut down the snow shower
activity. At the surface...high pressure will quickly build into the
region Monday night. This will allow for yet another very cold night
with wind speeds decreasing and mainly clear skies with a deep
snowpack in place.

High pressure will quickly shift east of the region on Tuesday...as
a deepening storm system tracks from the Central Plains to the upper
Great Lakes. Isentropic lift will increase...with a S-SW low level
developing and strengthening. Most model guidance have sped up the
timing as is typically the case with warm advection precipitation. The NAM
is lagging behind in terms of timing of onset of precipitation...but will
side towards the faster GFS/European model (ecmwf) timing and mention likely probability of precipitation
Tuesday afternoon for New York zones and chance probability of precipitation for western New
England. Thermal profiles indicate warming aloft late in the
day...but with the warm nose still below freezing will mention all
snow through 6 PM with some light accumulations.

&&

Long term /Tuesday night through Saturday/...
consensus and run to run consistency from guidance continues for a
mixed precipitation event Tuesday night into early Wednesday. Still
some questions as to how far north the mixed precipitation gets
since there is still a spread as to how far north the above freezing
layer aloft gets. There is a good consensus that the warming aloft
will be of a very short duration... and the boundary layer thermal
gradient will shift east quickly allowing cold advection to spread
into the region late Wednesday afternoon and night.

Based on the southwest boundary layer flow Tuesday night shifting
to west and northwest Wednesday...the steadier precipitation that
occurs Tuesday night may rapidly decrease in coverage Wednesday
morning. A line or band of scattered showers may accompany the cold
front during the day Wednesday as northwest winds become gusty
behind the front.

So...snow early Tuesday evening changes to a period of mix of sleet
and freezing rain later Tuesday night...changing to a brief period
of cold rain Wednesday morning as temperatures rise to or just above
freezing. Once the coverage of steadier precipitation ends and the
winds become gusty from the northwest...the mixing could then aid
temperatures in climbing well into the 30s...around 40 to lower 40s
in some areas. The southern Adirondacks...Lake George Saratoga
region and southern Green Mountains to parts of the northern
Berkshires may struggle to get into the middle 30s...and may see more
mixed precipitation than other areas. Still...there should be
enough of a mix...with a few inches of snow and light coating of
ice... where some advisory headlines may eventually be needed in
many areas Tuesday night into Wednesday morning. We still have a
little time to zero in on the specifics before considering headlines
for that time period.

By Wednesday night and Thursday...northwest winds remain gusty and
based on the direction of the low level flow...lake effect snow
shower activity looks to be scattered multi bands extending to
around the Schoharie valley and eastern Catskills. Some upslope
scattered snow shower activity also possible in the northern
Taconics to southern Green Mountains and northern Berkshires. There
could also be another weak wave of low pressure Wednesday night with
the northern edge of a precipitation shield that grazes the middle
Hudson Valley and northwest CT with some snow shower activity. Highs
Thursday in the 20s to near 30...but tens in the north.

Dry weather continues with below normal temperatures Friday...but
some signals of some moderation to temperatures Saturday. There cold
be some intervals of clouds and isolated snow shower activity
Saturday with the warm advection. Highs Friday in the 20s...with
teens in northern areas. Highs Saturday in the 30s...with 20s in
northern areas.

&&

Aviation /15z Sunday through Thursday/...
low pressure will approach from the southwest late today and
tonight...spreading clouds...and snow into the region.

VFR conditions are expected through at least 14z/today.
Thereafter...as intermittent light snow overspreads the
region...visibilities will gradually deteriorate into the MVFR...and
eventually IFR range by this afternoon. The snow should taper off
between 07z-09z...as visibilities become VFR but ceilings remain
MVFR. Including vcsh in all tafs after 07z-09z since the snow may
take some time to exit.

Calm winds early this morning will trend into the southeast to south
at 5-10 knots through the morning and into this afternoon. Winds will
become light west to northwest this evening.

Outlook...

Mon: low operational impact. Slight chance snow mainly in the morning.
Monday night: no operational impact. No sig weather.
Tue: moderate operational impact. Chance snow in the afternoon.
Tuesday nt-Wed: moderate operational impact. Snow/mixed precipitation to rain.
Thu: low operational impact. Isolated-scattered snow showers.
Fri: no operational impact. No sig weather.

&&

Hydrology...
no widespread Hydro problems are expected through the next 5 days. A
light to moderate snowfall is expected from this afternoon through
tonight. This snow will have no immediate impact on area waterways.
Dry weather is expected again from late Monday through Tuesday
morning. However...another storm system will impact the region late
Tuesday into Wednesday...with the possibility of snow...mixed
precipitation and/or rain.

Temperatures will remain below freezing through tonight.
Temperatures may briefly rise above freezing during the day on
Monday for some areas south of Albany...before another cold air mass
settles in for Monday night into Tuesday. With the continued cold
conditions in place...ice will continue to strengthen and thicken on
area rivers...streams...creeks...lakes...and ponds.

A brief warmup may occur on Wednesday...but the short timing and
magnitude of the warmth will likely not be enough to cause any Hydro
concerns. Another cold air mass will build in late Wednesday into
Thursday...with temperatures falling back below freezing.

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.

&&

Climate...
February 2015 will go down as one of the coldest months on record
across the region.

At Albany...February 2015 was the 2nd coldest February on record
with an average temperature of 12.7 degrees f. This also marked
the 4th coldest single month on record and the coldest month since
January 1994. Temperature records at Albany date back to 1820.
Here is a list of the all time coldest months at albany:

1) 9.7 degrees f January 1970
2) 11.8 degrees f January 1857
3) 12.1 degrees f February 1934
t4) 12.7 degrees f February 2015
t4) 12.7 degrees f January 1994

At Glens Falls...February 2015 was the coldest February on record
with an average temperature of 7.3 degrees f. This also marked
the 4th coldest single month on record and the coldest month since
January 1994. Temperature records at Glens Falls date back to
1945. Here is a list of the all time coldest months at glens
falls:

1) 4.9 degrees f January 1970
2) 6.5 degrees f January 1982
3) 7.1 degrees f January 1994
4) 7.3 degrees f February 2015

At Poughkeepsie...February 2015 was the coldest February on record
with an average temperature of 15.6 degrees f. This also marked
the 2nd coldest single month on record. Temperature records at
Poughkeepsie date back to 1949...although data is missing from
January 1993 to July 2000.

&&

Aly watches/warnings/advisories...
CT...Winter Weather Advisory until 7 am EST Monday for ctz001-013.
New York...Winter Weather Advisory until 7 am EST Monday for nyz032-
038>040-047-048-051-054-058>061-063>066-082.
Massachusetts...Winter Weather Advisory until 7 am EST Monday for maz001-025.
Vermont...Winter Weather Advisory until 7 am EST Monday for vtz013-014.

&&

$$
Synopsis...11/jpv
near term...jpv/wasula
short term...jpv
long term...NAS
aviation...NAS
hydrology...11/jpv
climate...jpv

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