Area Forecast Discussion
Issued by NWS Albany, NY

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760
FXUS61 KALY 252321
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
721 PM EDT SUN SEP 25 2016

.SYNOPSIS...
A large area of high pressure will allow for cool and clear
conditions to prevail across the region through tonight. Another
chilly night is expected with frost advisories in most areas, and
freeze warnings for the Adirondack Region. Dry weather should
prevail Monday as clouds increase in advance of a cold front. This
front will bring a period of rainfall Monday night, to be
followed by a period of mainly dry conditions for Tuesday into
Wednesday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Freeze warning remains in effect for most Adirondack zones. Frost
Advisory remains in effect for remainder of forecast area
tonight.

As of 715 PM EDT, skies remain clear, and with winds generally
less than 5 mph, temps are already beginning to tumble, with 50s
for most valley areas, and 40s across higher elevations and across
portions of the Lake George region.

Clear skies and light winds tonight will allow for ideal
radiational cooling. MOS guidance was too mild last night and
with cooler afternoon highs today, we will undercut the 12Z MOS
guidance by a couple of degrees. Some fog possible near bodies of
water overnight.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
The main weather impact will be Monday night with the approach
and passage of a cold front. A period of showers will accompany
the front as PWATs climb toward 1.50 inches. So some of the much
needed rainfall could be moderate with intensity.

Ahead of this front, surface ridge slides off to the east with a
strengthening southerly flow evolving through the day. Wind gusts
may increase late in the day as per the BUFKIT momentum
transfer/mixing heights we could see gusts at or above 20kts
(especially in the Hudson River Valley). As the thermal column
moderates, high temperatures for valley locations should climb to
generally between 65-70F with 60-65F for the higher terrain.

As showers move through Monday night, thermal column continues to
moderate as H850 values climb to around +10C. This should keep
conditions rather mild Monday night with mainly 50s across the
region.

In the wake of the frontal passage, NCEP model suite differs a bit
with exit timing as the NAM is about 3 hours faster than the GFS.
Regardless, we will diminish PoPs from west to east Tuesday
morning as most of the region should be dry as we find ourselves
within the dry slot as main upper/surface low remains well
upstream of the region. The only exception to the PoP field will
be across northern Herkimer and northwest Hamilton counties where
some lake moisture and closer proximity to the cyclonic
circulation to keep slight chance PoPs through the day. As
southwesterly flow regime will be in place and a milder start to
the day, afternoon high temperatures under at least partial
sunshine should allow for valley tempertures to climb into the
upper 60s and middle 70s.

Tuesday night, consensus favors the vertically stacked low over
the Great Lakes to become further disconnected and dive southward
overnight toward the Ohio Vally. This leaves our area into a cul-
region with little synoptic flow. Under at least partly cloudy
skies (could be more clearing overnight) and previous rainfall,
could be ideal conditions for fog development as we will place
this into the forecast/grids at this time. Overnight lows will be
mainly into the 40s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
There remains considerable uncertainty through much of the long term
portion of the forecast, as a large mid/upper tropospheric low is
expected to develop across the lower Ohio Valley region, before
potentially dipping southeast into the southern Appalachians before
gradually lifting north or northeast and weakening toward next
weekend. How quickly the system lifts north/northeast, and the
strength of deep upper level ridging developing to the north and
northeast of this evolving system will ultimately determine how fast
any clouds and rain from this system develops northward into our
region.  The 12Z/25 GFS, mean GEFS and GEM suggest earlier timing,
with rain developing across the region Thursday-Friday, before
tapering to scattered showers by next weekend as the system weakens
and lifts northward. The 12Z/25 ECMWF, on the other hand, has
stronger ridging developing across northern New England/southeast
Canada, delaying the onset of any rainfall until next weekend,
although some showers could occasionally brush extreme southern
areas at times as early as late Thursday.

For now, have sided a bit more with the 12Z GFS/GEFS and GEM,
indicating chc pops developing northward for Thu-Fri, before
tapering to isolated-scattered showers next weekend, in accordance
with superblend, however this remains a low confidence forecast and
it is very likely that additional changes will be made to precip
timing during this period.

Temperatures will also be highly dependent on clouds/rainfall, with
slightly warmer daytime temperatures reaching the 60s/lower 70s or
even warmer if rain holds off, while highs may only reach the 60s,
if not cooler, when rain occurs. Again, based on superblend, current
forecast indicates mid 60s to lower 70s Wed for highs, then mainly
60s for Thu-Sun, except 50s across higher terrain. Overnight lows
should be in the mid 40s to lower 50s through the period, warmer
during periods of clouds/rain.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
High pressure overhead tonight will slide off the New England
coast Monday, as a frontal system approaches from the Great Lakes.

Generally VFR conditions are expected through at least
00Z/Tuesday. However, will have to watch for patchy ground fog
development at KGFL, as local swamps and Lake George could
contribute to at least brief reductions in VSBY between 06Z-
10Z/Mon. Otherwise, just high to mid level clouds increasing on
Monday.

Winds will become light/variable to calm overnight, then become
south to southeast Monday at 5-10 KT. Winds could gust up to 15-20
KT at KALB late in the day as some funneling effects up the Hudson
River Valley occur.

Outlook...

Monday Night: High Operational Impact. Likely SHRA.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. Patchy FG.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thursday: Moderate Operational Impact. Chance of SHRA.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Chance of SHRA.

&&

.FIRE WEATHER...
Ii will be dry through Monday with our next chances for rainfall
Monday night into Tuesday morning.

Minimum relative humidity values this afternoon are expected to be
in the 30s with a recovery to 85 to 95 percent tonight. Minimums
Monday afternoon are expected to be in the mid 30s to mid 40s
with a recovery to 90 to near 100 percent Monday night with
showers/period of rain.

Northwest to north winds at 5 to 10 mph this afternoon. Winds
will diminish tonight becoming light and variable with a southerly
flow developing Monday. Wind gusts may approach or exceed 20 mph
Monday late afternoon.

&&

.HYDROLOGY...
It will be dry through Monday with our next chances for needed
rainfall coming Monday night into Tuesday as a low pressure
system approaches from the west and moves across the region.
Rainfall amounts of about a third of an inch up to around a half
of an inch are expected.

Precipitation departures so far this year at our climate sites
are: Albany NY: -3.42 inches
Glens Falls NY: -6.21 inches
Poughkeepsie NY: -11.36 inches
Bennington VT: -6.52 inches
Pittsfield MA: -7.96 inches

The U.S. Drought Monitor released on September 22nd shows drought
conditions have changed very little across the region. For details
visit: www.drought.gov

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...Frost Advisory from 2 AM to 8 AM EDT Monday for CTZ001-013.
NY...Frost Advisory from 2 AM to 8 AM EDT Monday for NYZ038>041-043-
     047>054-058>061-063>066-082>084.
     Freeze Warning from 2 AM to 8 AM EDT Monday for NYZ032-033-042.
MA...Frost Advisory from 2 AM to 8 AM EDT Monday for MAZ001-025.
VT...Frost Advisory from 2 AM to 8 AM EDT Monday for VTZ013>015.

&&

$$
SYNOPSIS...IAA/KL/BGM
NEAR TERM...IAA/KL/BGM/OKeefe
SHORT TERM...IAA/BGM
LONG TERM...KL
AVIATION...KL/OKeefe
FIRE WEATHER...IAA/BGM
HYDROLOGY...IAA/BGM



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