Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 202054
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
354 PM EST Fri Jan 20 2017

.SYNOPSIS...
A weak disturbance will bring some light precipitation to the
area late today and tonight, mainly as rain. However across
portions of the southern Adirondacks into the Lake George region
and in parts of southern Vermont there is chance of freezing
rain. Fair weather returns for much of the weekend.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 315 PM EST, swath of rain currently over northeast PA
continues its slow progression, weakening as it lifts NE towards
our area. Looks like points to the south and west of the
Capital District will receive the steadier rainfall this
evening/overnight. As the precipitation builds north and east it
should steadily shrink in coverage so that the Mohawk Valley to
Capital District and Berkshires to NW CT will see just chances
and some areas of the southern Adirondacks and Lake George area
small to slight chances.

Temperatures slowly cooling tonight will support some possible
mixed precipitation in the western Adirondacks and southern
VT/northern Berkshires. Lows tonight will be in the 30s but
near or just below freezing in the western Adirondacks, Lake
George area and southern VT. The biggest question mark will be
the cloud cover tonight. There is some clearing/thinning of
clouds along and north of the Capital District and if this
continues, temperatures might drop off quicker than expected
tonight. This would lead to a higher probability of frozen
precipitation so will have to monitor this as the night
progresses.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
Precipitation should exit around daybreak with perhaps some
lingering drizzle in the western Adirondacks into the afternoon.
Otherwise, there should be some breaks in the clouds with
intervals of clouds and sun for the day Saturday. Surface flow
turns to the south, ushering in warmer air. Afternoon highs are
expected to reach the low 40s to low 50s.

Upper low begins it initial approach to our region from the
northern Gulf coast states and SE US Sunday and Sunday night.
Coverage of clouds, especially mid and high clouds, should
increase through Sunday and Sunday night. Winds will be lighter
and highs Sunday are expected to be well into the upper 40s but
around 40 in northern areas.

Northern stream upper energy dropping southeast through eastern
Canada is expected to increase the downstream upper confluence,
supporting a strengthening surface high pressure in southern
and southeastern Canada. This low level ridging is expected to
push colder and drier low level air south into our region Sunday
night as the southern stream upper energy and strengthening
warm/moisture advection pushes north. These opposing forces will
contribute to enhanced frontogenesis and forcing that will
affect precipitation type as precipitation spreads across our
region through Sunday night.

During the onset of the precipitation Sunday afternoon/evening,
it should be mostly rain. As colder air drains southward and
low level temperatures trend toward wet bulb temperatures as
intensity of precipitation increases, mixed precipitation may
build south across much of the region. Based on thermal
profiles, it looks like mainly a rain/snow/sleet mix but will
have to keep an eye for areas of freezing rain as we get closer
to the event.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Extremely low confidence forecast in the long term as model guidance
is having a difficult time resolving the evolution of the coastal
low early next week. The GFS has a more inland track and at one time
has several areas of low pressure before low tracks off northeast
coast into the Gulf of Maine by Tuesday evening. The NAM as far out
as it goes in time keeps the primary low over eastern Virgina at 84
hours with a coastal low off Delmarva and the ECMWF, which has
perhaps the cleanest resolution, brings the low northeast right
along the Atlantic seaboard to near Block Island by 12Z Tuesday and
then into the Gulf of Maine by 00Z Wednesday. Given all of this
uncertainty will basically forecast ptypes as only rain or snow and
keep snowfall amounts down with highest accumulations confined to
the mountains from the southeast Catskills to the southern Green
mountains with lesser amounts across the northwest portion of the
forecast area due to lower QPF as well as in the valleys where in
addition to marginal temps some significant downsloping is likely to
occur due to a strong easterly flow in the lower levels. Have
forecast liquid equivalent amounts from 00Z Monday through 12Z
Tuesday of 0.50 inch northwest to 1.50 inches southeast.

After this system goes by expect a ridge of high pressure to build
into the region on Wednesday before a clipper type system approaches
for Wednesday night and has some precip lingering into Thursday as
it exits into the Canadian Maritimes.

As for temps expect highs on Monday in the upper 20s to upper 30s
with highs on Tuesday in the 30s to lower 40s and mid 30s to mid 40s
on Wednesday with lower 30s to lower 40s on Thursday. Lows will be
in the mid 20s to mid 30s Sunday night and Monday night in the 20s
to around 30 Tuesday night and in the mid 20s to mid 30s Wednesday
night.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
A small ridge of high pressure over the region today will lead
to dry conditions through much of the day. However, low level
moisture is trapped beneath a strengthening inversion aloft, so
clouds are expected to remain in place through the period. Will
trend towards a more pessimistic ceiling forecast due to
widespread cigs currently in place and not much opportunity for
mixing over the next 24 hours. Cigs will be mainly in the
MVFR/VFR range, with slight improvement this afternoon.

Cigs expected to lower again after dark, as a weakening upper
level disturbance approaches from the mid Atlantic region, but
will bring some light showers to the terminals. Will mention
VCSH at KGFL this evening, with prevailing -SHRA developing at
KALB/KPOU/KPSF. Conditions are expected to deteriorate to mainly
MVFR once the showers begin, although some periods of IFR are
possible late tonight. Conditions will improve again Saturday
morning with the rain moving out as weak high pressure builds
across the region.

Winds will generally be light and variable through the period.

Outlook...

Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Moderate Operational Impact. Chance of RA.
Sunday Night: Moderate Operational Impact. Chance of RA...SN.
Monday: High Operational Impact. Likely RA...SN.
Monday Night: High Operational Impact. Definite RA...SN.
Tuesday: High Operational Impact. Likely RA...SN.
Tuesday Night: Moderate Operational Impact. Chance of RA...SN.
Wednesday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
Some light precipitation is possible this evening into tomorrow
morning, but QPF amounts will be a tenth of an inch or less.
Daytime temperatures will be above normal through the weekend,
although overnight lows will fall around or just above freezing
for most areas. As a result, some very minor snowmelt may occur
in a few areas, but it will likely have little impact on rivers
and streams.

Widespread precipitation will occur early next week, but there
are still questions regarding the exact precipitation type and
amounts. The latest MMEFS do not show any flooding on area
rivers and streams, although some river rises are likely to
occur.

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...NAS
NEAR TERM...11/NAS/JVM
SHORT TERM...NAS/JVM
LONG TERM...11
AVIATION...11/JPV
HYDROLOGY...NAS/JVM


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