Area Forecast Discussion
Issued by NWS Albany, NY

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649
FXUS61 KALY 231417
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
917 AM EST Thu Feb 23 2017

.SYNOPSIS...
Mild conditions with well above normal temperatures are
expected to persist into Saturday. A weak cold front will cross the
region this evening bringing some showers. The front will stall just
south of the region tonight, before lifting back northward as a warm
front on Friday. There will be increasing chances for heavy rainfall
associated with a strong cold front passage late Saturday into
Saturday night. Gusty winds are possible along the cold front
and into Sunday as much colder air rushes in.

&&

.NEAR TERM /THROUGH TONIGHT/...
Many areas sunny this morning but axis of mid/high clouds to
the west will be building in through the day with scattered
showers in western and northern areas by sunset. Based on area
12Z soundings, with full mixing potential, temperatures this
afternoon could be even a few degrees warmer than current
forecast but winds are expected to be light. Current forecast is
solidly above record levels. So, just minor adjustments to
temperatures and sky cover through this afternoon. Previous AFD
has a few more details and is below...

Today, surface low ahead of a quick-moving upper impulse will
track across southern Quebec, putting the local area into the
warm sector. Another unseasonably warm day is on tap, with H925
temps averaging around +10C, which is around +2 sigma. Thus far
during the warm stretch, guidance has been on the low side,
possibly underestimating the degree of mixing. Think that trend
will continue today, so have forecasted high temps a few degrees
above MET/MAV guidance and closer to the HRRR 2-m temps.
Southwest winds above the surface at low levels from the
southwest should allow for some downsloping from the
Catskills/Helderbergs as well. There is a good chance that we
break the high temp of 62 at Albany set in 1984. Only fly in the
ointment is if the area of low/mid level clouds over OH/PA work
into the region. NAM RH progs suggest that they may not arrive
until later in the afternoon. Have also increase winds a bit
expecting to mix into stronger winds than forecast soundings
indicate.

Chance for showers late afternoon into the overnight hours as
the system`s cold front passes through and washes out over the
center of our CWA. Best chances across the Adirondacks.
Otherwise, another mild night in store with lows in the mid-30s
to mid-40s. The front will lift back north as a warm front late,
possibly focusing more showers across the northern portions of
the region.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Deep upper disturbance will go negatively tilted across the
Upper Midwest, resulting in a strong surface low tracking
roughly from northern Missouri to western Quebec from 12Z Friday
to 00Z Sunday. The aforementioned warm front connected to this
system will continue to lift northward through our region
Friday, possibly resulting in a few showers and perhaps even a
thunderstorm, especially in the morning and from the Capital
District northward. More clouds/low-level moisture will likely be
around so forecast highs are not quite as warm as Thursday, but
if any breaks in the cloud cover can develop, highs could be
higher than what we have forecast. Friday afternoon into
Saturday morning, we look to be firmly in the warm sector under
strong upper ridging, so expect mainly dry conditions aside
from possible pockets of drizzle or a light shower or two.

Models are in pretty good agreement that a very strong cold
front will track through the local area Saturday afternoon into
Saturday evening. Forecast temp contrasts across this front are
impressive - for instance, NAM shows 2-m temp difference across
the front of around 20F, and 850 mb temp difference near 10C,
as it tracks through the local area. Though forecast instability
is expected to be very little, there is some concern for a
strongly forced, narrow frontal rain band that could mix some of
the strong wind field down to the surface. Also have to worry
about the downward momentum transport immediately behind the
front. NAM cross section shows the front-normal component of the
winds of 35-40 kt just off the surface, along with a midlevel
dry intrusion, which CSTAR research has shown to be associated
with high wind events. NAM also shows 3-h pressure rise center
of 7-8 mb tracking through the area. Will continue to mention
this potential in the HWO. A period of moderate to heavy
rainfall is likely along and behind the front (see Hydrology
discussion below for more details), tapering to showers several
hours after frontal passage. Lake effect snow showers will
commence downstream of Lake Ontario late in the night with 850
mb temps falling toward -15C. Windy conditions will continue
overnight.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A return to more seasonable weather is in store during the long term
period along with several chances for at least some snow.

For Sunday...In the wake of the cold front it will be a blustery day
with strong gusty winds and much more seasonable temperatures. There
will also be some lake effect snow showers downwind of Lake Ontario
mainly across the western Adirondacks and Mohawk Valley with some
minor accumulations possible. Highs on Sunday will be in the upper
20s to mid 40s with west to northwest winds gusting over 40 mph at
times.

For Sunday night...Some lake effect will continue but be primarily
confined to the northwest Adirondacks with the remainder of the area
dry. It will be much cooler than recent nights with lows ion the
upper teens to upper 20s.

Monday and Monday night...A clipper type system will be moving from
the upper Great Lakes Monday morning quickly into the Canadian
Maritimes by late Monday night. This clipper type system will leave
a cold front draped across northern New York late Monday night. As a
result there will be a chance of precipitation mainly across the
northern half of the forecast area. Highs on Monday will be in the
mid 30s to mid 40s with lows Monday night in the upper teens to
lower 30s.

Tuesday through Wednesday...Another system approaches from the Great
Lakes region bringing increasing chances of precipitation. At this
point it appears it will be cold enough for some snow at least
across the northern half of the forecast area, but the precipitation
will likely change to rain by Wednesday. Highs on Tuesday are
expected to be in the upper 30s to upper 40s with lows Tuesday night
in the upper 20s to mid 30s and highs on Wednesday in the mid 40s to
mid 50s.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
VFR conditions will prevail until late tonight at the TAF sites
after which MVFR conditions are expected with some fog at KPOU
and KPSF. There may also be some fog at KGFL and KALB but not
confident enough to include in TAFs at this time. Skies during
today should be mainly SCT-BKN045.

Winds will be mainly light at less than 10 kts from the south
to southwest for much of the TAF period. Winds will become light
and variable to calm tonight.

Outlook...

Friday: Moderate Operational Impact. Chance of SHRA.
Friday Night: Moderate Operational Impact. Chance of SHRA.
Saturday: High Operational Impact. Breezy Likely SHRA...RA...TSRA.
Saturday Night: Moderate Operational Impact. Chance of SHRA.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
A mild and increasingly moist airmass will be in place through
Saturday. Light showers are possible later today into Friday.
This will cause gradual snow melt and subsequent runoff. Also, a
quick-moving, strong storm system may bring a period of
moderate to heavy rainfall Saturday afternoon and evening. The
Meteorological Model Ensemble River Forecasts /MMEFS/ continue
to suggest significant river rises will occur, with flooding
possible Saturday into Sunday due to the combination of snow
melt and moderate to heavy rain. Total QPF forecast of 0.50 to
1.50 inches is forecast through Saturday night, with the lowest
amounts in the Mid- Hudson Valley and Northwest Connecticut,
and the highest amounts over the Western Adirondacks. The
majority of the rainfall is expected to occur with the frontal
passage Saturday afternoon/evening.

At this time, at least minor flooding appears possible for at
least a few points along main stem rivers, especially over the
Adirondacks and Green Mountains where the snowpack is greatest.
We will have more specific information as the weekend draws
nearer. A flood watch may be necessary if confidence in flooding
increases.

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.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...11/Thompson/JPV
NEAR TERM...NAS/Thompson
SHORT TERM...Thompson
LONG TERM...11
AVIATION...BGM/11
HYDROLOGY...Thompson/JPV



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