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Area forecast discussion 
National Weather Service Albany New York
355 PM EST Sat Dec 27 2014

Synopsis...
surface high pressure will track off the southeast coast tonight.
Meanwhile...an approaching cold front will bring a round of
showers across the region tonight. A cooler and drier day is
expected Sunday into Sunday evening in the wake of the frontal
passage. Looking into the last week of 2014...a very large
Canadian high pressure system will ridge into the northeast with
generally fair and more seasonable temperatures.

&&

Near term /through Sunday/...
as of 330 PM EST...
stratus deck continues to erode across the County warning forecast area and surface
temperatures have responded with mainly middle 40s to lower 50s
that extended into the middle Hudson Valley and northwest
Connecticut. Water vapor loop reveals a large subtropical high
across southern Florida...Cuba and the Bahamas as h500 heights
were just above 590dm. But a large positive tilted trough was
across noam with a deep moisture tropical connection from the
eastern Pacific. A short wave was racing northeast from the
central Great Lakes region towards James Bay. This wave surface
reflection too was racing northeastward with its associated cold
front that extended from the southern lakes through the
Mississippi River valley. Regional radar mosaic does reveal ample
shower activity along the Gulf Coast...Ohio River valley ahead of
the front with more along and just behind the cold front. Latest
hrrr/hireswrf reflectivity forecasts keep our region dry through
this early evening /approx 02z/. Thereafter...combination of
Theta-E advection...low level baroclinicity increasing and upslope
conditions should result in showers developing across the Mohawk
Valley into the Adirondacks through the evening hours. These
showers should expand further with the approach of the cold front
tonight with a high chance to likely probability of precipitation for most of the region.
The frontal movement forward progress will likely slow down
somewhat as the surface features become quasi-parallel to the
upper flow late tonight into Sunday morning. This will keep the
threat of showers in the forecast for the southern 2/3rds to
southern 1/2 of the County warning forecast area through early Sunday morning.

As for thermal profiles...due to a milder afternoon and timing of
the cold air advection a little further delayed...seems most of
the precipitation will fall as rain. Across portions of the dacks late
tonight...its possible some of the showers to mix with snow but
not expecting accumulations of snow at this time.

Through Sunday...the cold front will steadily progress southeast
as drier air filters southward into the dacks region. We will
diminish probability of precipitation from north to south through the day as h850 temperatures
drop back to near 0c for the middle Hudson Valley and northwest CT to -10c
into the norther Adirondack region within our County warning forecast area. Due to the
drier air...Lake Ontario response to the cold advection appears
minimal at this time. Should remain rather mild for this time of
the year with upper 30s to middle 40s expected.



&&

Short term /Sunday night through Monday night/...
Sunday night...a narrow anticyclonic ridge axis will extend from
the Ohio River valley and into the northeast corridor as cold air
advection continues. This should keep our weather tranquil yet a
noticeable chill in the air. There will likely be some stratocu
development overnight downwind of Lake Ontario as those Delta T/S
increase as recent model trends favor some light snow shower
activity late Sunday night into portions of the southern dacks and
western Mohawk Valley...and per the trajectory forecasts...may
bring some light snow showers into the Schoharie valley late at
night. As for low temperatures...mainly 20s.

Monday...cold air advection continues as another surface cold
front/trough axis slides southward across the region. Mainly
stratocu clouds and some light snow showers/flurries will impact
portions west of the Hudson through the day. H850 temperatures will drop
back to between -10c and -15c.

Monday night...the Arctic high building southward into Montana and
the North Plains...its influence will extend into the Great Lakes
region and northeast. This will result in partly cloudy-mostly clear skies as
temperatures as temperatures drop back into the teens for most
areas...single digits into the dacks.

&&

Long term /Tuesday through Saturday/...
the extended period starts out seasonably cold as a large high
pressure continues to build southeastward from Montana. This will
continue to bring modified Arctic air into our region.

Tuesday looks to be dry everywhere with at least partial sunshine as
an anticyclonic flow is northwesterly. By Wednesday...as the high
builds to our southwest...the flow looks to become more westerly
which should allow for some lake effect...to the Lee of
Ontario...mainly across the Adirondacks. Otherwise it should remain
dry with partial sunshine outside of the Adirondacks.

By Friday...the high pressure will have translated to our
south...off the middle Atlantic coast. A southerly flow will ensue.
Clouds will increase on that day...along with possibility of a
little snow shower activity.

Then Friday night into Saturday...a disturbance riding in the
subtropical jet...move lift into the Ohio Valley. Initially it look
as if it might be cold enough for all snow. However...now it looks
as if this system will likely pull enough warm air for at least a
wintry mix...if not mostly rain...at least from Albany southward.
However...there is still the possibility that the storm could reform
further east off the eastern Seaboard...which would hold cold air in
longer. Right now...most guidance does not support the latter
thinking...but the possibility remains.

Our forecast while leaning with the warmer solution...will have the
possibility of snow Friday night...changing to a rain/snow mix
north...and mostly rain from I-90 south by Saturday afternoon.
Obviously this scenario bears watching as there could also be period
of sleet and freezing rain (although neither are mentioned this far
out).

High temperatures on Tuesday and Wednesday will range from around 20
degrees across our northwest zones...to lower 30s in our
southeastern zones. Thursday looks a few degrees warmer everywhere
with temperatures reaching just above freezing in the middle Hudson
Valley. Friday high temperatures are projected to be from the middle
20s across the Adirondacks...lower 30s capital region and
surrounding areas...middle 30s southeast. By Saturday...it looks as if
everyone should be in the 30s...mostly above freezing...with areas
south of the capital region possibly exceeding 40 degrees.

Lows will in the teens north...lower to middle 20s south Tuesday
through Thursday nights. By Friday night lows to range from the middle
20s northwest...to around freezing in the capital region and points
south. Obviously a slight shift in temperatures will help determine
what kind of precipitation falls Friday night into
Saturday.

&&

Aviation /20z Saturday through Thursday/...
high pressure will shift eastward with the center of the surface high
shifting offshore the southeast coast this afternoon and evening
as a low pressure system approaches. The surface low is forecast to
move across the Great Lakes region into eastern Canada today and
tonight dragging its associated cold front into the region. Aloft
southwest flow will develop between the departing ridge and the
advancing trough. Lower level clouds have continue to impact kgfl...kalb
and kpsf. These clouds should linger well into the afternoon with
them breaking up as we head into the evening for a period. Cirrus
clouds will continue to stream over kpou. Clouds cover will
spread back across the area as the low pressure and cold front
approaches with chances for showers increase from northwest to
southeast across the forecast area tonight as the low level jet
associated with the system moves in and across the region. Chances
will be greatest to the northwest of the capital district. MVFR
conditions are not expected until late in the taf period and they
will linger through the end of the taf period at kpou.

Light south-southwest flow develops today with a more westerly
flow at kpsf. Winds will become west in the wake of the front on
Sunday.

Outlook...
Sun night-Thu: no operational impact. No sig weather.

&&

Hydrology...
river levels continue to recede across the region...and will
continue to do so for the next week.

A cold front is expected to bring rain showers with a mix of rain/snow
across higher elevations late tonight into Sun morning. Quantitative precipitation forecast with this
event will be on the order of 0.10 to 0.40 inch...generally
will have minimal impacts to river flows.

Generally dry conditions...and colder temperatures...are expected
into at least early next week. By then end of the period with
decreasing flows and normal temperatures ice may begin to form.

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...bgm
near term...bgm
short term...bgm
long term...hwjiv
aviation...iaa/11
hydrology...bgm



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