Albany Office Forecast Discussion

363
FXUS61 KALY 202337
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
737 PM EDT Thu Sep 20 2018

.SYNOPSIS...
A low pressure system will impact the region. A warm front will
lift through late tonight into Friday morning with southerly
winds becoming breezy during day Friday. A cold front will
sweep across the region late Friday night. A line of showers with
embedded thunderstorms is expected ahead of the cold front with
some storms possibly producing strong winds especially north
and west of the Capital District. Fair weather with seasonably
cool temperatures are expected for the weekend.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 737 PM EDT...Strong upper level ridging is anchored over
the southeastern US. Our region is on the northern fringe of
this ridging, with plenty of mid and high level moisture
streaming into the region from the Great Lakes.

At the surface, a low pressure system will be on the approach
moving into the Great Lakes region and begin to impact the local
area tonight as its associated warm front lifts through. MRMS
imagery already shows some light showers starting to move into
the western Adirondacks. 3 km HRRR/NAM suggests these showers
will increase in coverage later this evening and into the
overnight for far northern parts of the area. Precip looks
light, but cannot rule out on and off showers for the
Adirondacks and Lake George-Saratoga Region.

With a persistent southerly flow, dew points will be in the
rise across the area and increases late at night. The
increasingly low-level moisture will also allow for low clouds
to develop through the night, with most areas seeing overcast
low stratus by daybreak.  Expecting lows in the 50s to near 60.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Strong to severe thunderstorm possible in Friday evening into
the overnight north and west of the Capital District.

The area will be in the warm sector Friday with breezy southerly
flow developing. Low pressure will deepen as it moves
northeastward passing well to our north and west of our area
and across eastern Canada near Hudson Bay Friday and Friday
night. The system`s cold front will sweep across the region
late Friday night as a short wave trough also passing over the
region. The approach of the short wave trough will result in
height falls across the region and ascent however this feature
will weaken overnight as it moves through.

We are looking at a low CAPE, high shear environment with weak
mid level lapse rates with the passage of the cold front. The
shear will be increasing at night to 40 to 60 knots however CAPE
will be decreasing with loss of the heating. The low level jet
ahead of the cold front is forecast to become quite strong at 40
to 60 knots.

The Storm Prediction Center pulled back on the slight risk across
a portion of the local area, south and east of Capital District,
with their Day 2 update earlier today as the CAPE will be very
limited by the time the cold front reaches this area. This area
is now in a marginal risk. The greatest risk for any strong to
severe storms will be to the north and west of the Capital
District as on-going convection moves into the area and there
should be modest CAPE to work with. The main threat is for
strong to damaging wind gusts due to the strong winds field.

With the passage of the front, a drier and seasonable cool
airmass will be ushered in for the weekend. High pressure will
build in at the surface as the flow aloft becomes zonal across
the region. Looking at highs from the upper 50s to lower 70s
Saturday and lows from the upper 30s to lower 50s Saturday
night.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
The second half of the weekend into early next week will feature
seasonable temperatures very fitting for the first days of autumn.
However, we then will be monitored a period of wet weather Tuesday -
Wednesday which will lead to higher humidity and warmer temperatures.

High pressure from the Great Lakes will shift eastward on Sunday
with H850 isotherms between +5 and +8C which should translate to
highs in the mid - upper 60s. Overall, expecting a mostly sunny day
with perhaps an exiting cirrus deck in the morning for the mid-
Hudson Valley and NW CT. Heading into Sunday afternoon, a secondary,
moisture starved cold front looks to enter the Adirondacks and then
push south and east through sunset. However, the frontal passage may
only manifest itself through a few increasing clouds and the surface
winds shifting from the northwest to northeast. Given the wind
shift, this could be called a back-door cold front.

A large area of strong canadian high pressure (1035-1038mb) builds
into the Northeast in its wake Sunday night and Monday. The latest
guidance shows the high settling into the Gulf of Maine by Monday
afternoon with signs of cold air damming draining cooler air down
into eastern NY/western New England. Thus, high temperatures Monday
should be a bit cooler than Sunday only reaching the low - mid 60s.
Ridging strengths aloft so we should enjoy mostly sunny skies for
most of the day.

500mb ridge axis shifts eastward into New England Monday night as a
longwave trough deepens over the northern Great Plains/southern
Canada. With upper level flow becoming southwesterly, expect
increasing clouds overnight so overnight low temperature should not
be as cooler previous nights, only falling into the upper 40s/low
50s. Clouds continue to thicken and overspread the region Tuesday
with the threat for showers gradually increasing through the day
from southwest to northeast. Given the strength of the high pressure
over northern New England, showers may struggle to get into our area
so only introduced slight chance POPs for the Mohawk Valley and
Catskill for the first half of Tuesday. However, isentropic lift
associated with warm front pushing northeastward from the mid-
Atlantic looks increase enough after 18z that we increased POPs to
chance for the Mohawk Valley, Capital District and the mid - Hudson
Valley. Still, we may only see scattered showers. Southern VT and
the upper Hudson Valley may struggle to see showers again because of
the aforementioned high.

Tuesday night we should be in the system`s warm sector so expecting
a few scattered showers with more humid and mild conditions. The
warm front should move northeast into northern New England by this
time so placed widespread chance POPs throughout our CWA. The best
chance for more widespread rain then looks to arrive Wednesday as
the system`s cold front moves into eastern NY/western New England
from northwest to southeast. Some instability cannot be ruled out
given dew points could climb into the upper 50s so also include
slight chance of thunder. High temperatures Wednesday ahead of the
front could climb into well into the 70s so beside the chance of
rain, expect above normal temperatures for late September.

Front clears out by Thursday with high pressure building in its wake
so expect a drier, more pleasant Thursday.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A developing southerly flow will allow low-level moisture to
increase through the overnight hours. Although most valley areas
are VFR with just bkn-ovc cigs at 4-6 kft, ceilings will lower
to 1500-3000 ft by late tonight. At this point, IFR conditions
aren`t expected, but MVFR low stratus looks to develop for all
sites. A few showers are possible around KGFL from about
midnight to daybreak, which may lower visibility briefly down to
4-6 SM. Light south to southeast winds will increase to 5-10
kts by late tonight for all sites.

During most of the day on Friday, flying conditions will be
MVFR due to low clouds thanks to abundant low-level moisture
trapped close to the surface. Ceilings will be around 2-3 kft
through the day, although some improvement back to VFR is
possible by mid afternoon for KALB. Southerly winds will
increase to 10 to 15 kts through the day, with a few higher
gusts, especially at KALB. Any showers or t-storms ahead of a
frontal boundary look to impact the region after the end of TAF
period (00z Saturday).

At this point, will need to monitor for LLWS for late tonight
and into Friday, as 2 kft winds increase to 35-40 kts thanks to
a strong low-level jet. Surface winds should remain strong
enough to prevent LLWS, but if surface winds do lighten up, this
could become an issue.

Outlook...

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

&&

.FIRE WEATHER...
A low pressure system will impact the region. A warm front will
lift through late tonight into Friday morning with southerly
winds becoming breezy during day Friday. A cold front will
sweep across the region late Friday night with a line of showers
with embedded thunderstorms. Fair weather with seasonably
cool temperatures are expected for the weekend.

&&

.HYDROLOGY...
A low pressure system will impact the region with its warm
front lifting to our north late tonight into Friday morning
followed by a cold front late Friday night. North and west of
the Capital District a third to about an inch of rainfall is
forecast. Much of this area is in need of rainfall. Lesser
amounts are expected to the south and east. Outside of some
ponding of water on roadways flooding is not expected.

Fair and seasonably cool for the weekend.

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...IAA
NEAR TERM...IAA/Frugis
SHORT TERM...IAA
LONG TERM...Speciale
AVIATION...Frugis
FIRE WEATHER...IAA
HYDROLOGY...IAA

NWS ALY Office Area Forecast Discussion