Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 230609
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
209 AM EDT Fri Jun 23 2017

.SYNOPSIS...
A more humid air mass will return tonight into Friday as a warm
front moves through the region, along with increasing chances
for showers and thunderstorms, some of which may produce locally
heavy rainfall. The showers and thunderstorms should continue
Friday night, before gradually tapering off Saturday as a cold
front moves through and south of the region. Another upper level
disturbance could trigger a passing shower or thunderstorm
Sunday.

&&

.NEAR TERM /THROUGH TODAY/...
As of 145 am, mid and high clouds have thickened over the
forecast area per IR imagery. Batch of showers and thunderstorms
over Lake Ontario associated with lift along the lower
tropospheric warm front is expected to push into far northern
portions of our forecast area (Southern Adirondacks and perhaps
the Lake George Saratoga Region) after around 07Z per latest
HRRR which appears to have a good handle on the activity.
Elsewhere, mainly dry conditions should prevail, but have kept
in slight-low chance PoPs for anything to bubble up in the
increasingly moist, slightly unstable environment.

Previous discussion...As of 1043 PM EDT...A few light rain
showers associated with the warm advection/isentropic lift ahead
of a warm front over west- central NY extending southeast over
the lower Hudson Valley and Long Island continues to lift slowly
north/northeast tonight. The 00Z KALY sounding continues to be
dry in the low- levels with mid-level moisture between 7-12 kft
AGL. The PWAT has increased from 0.70" at 12Z to 1.32". We
slowed down the trend for more widespread showers and sct
thunderstorms into locations west/northwest of the Hudson River
Valley until around midnight or shortly thereafter. The latest
NAM12 and the 3-km NAM and HRRR have better shower and
thunderstorm coverage ahead of the warm front over the southern
Adirondacks between 05Z-09Z with Showalter indices of 0 to -3C
on the NAM and MUCAPE close to 1000 J/kg. The warm advection and
H1000-850 theta-e advection will increase overnight with sfc
dewpts rising into the 60s and PWATS to 1.4-1.7 inches. Some
brief bursts of heavy rainfall will be possible. Lower chance
pops south and east of the Capital Region are likely tonight, as
the better synoptic forcing is north and west. Lows tonight
will be in the 60s to close to 70F in the mid-Hudson Valley and
Capital District.

Friday could be an active day as combination of high moisture
content, approaching pre-frontal and main frontal zones and
positive tilted trough could allow for some training cells to
evolve. Question is overall instability and latest model trends
are less with the QPF. Yet if we are able to see breaks in the
overcast then greater instability can be realized hence the
marginal risk continued by SPC. The main threat will be from
heavy rainfall as PWATs are at or above 2" but through the day
not widespread enough for headlines at this time. We will
continue to watch and collaborate along with future upstream
trends and guidance.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
Friday night, as upper level jet energy, and the low/mid level
thermal gradient slowly approach from the west, chances for
showers and thunderstorms should continue well through the night.
Locally heavy rainfall will be possible, as PWAT`s remain close
to 2 inches, especially for areas near, and to the south and
east of Albany. It will remain warm and humid, with low
temperatures only falling into the mid/upper 60s.

Saturday, still could be a few rounds of showers and
thunderstorms from the Capital Region and points south and east
in the morning, as the cold front slowly settles southeast,
while some of the remnants, or moisture associated with Cindy
rides just south/east of the frontal boundary. Locally heavy
downpours will remain possible, especially across portions of NW
CT, the mid Hudson Valley, and southern Berkshires. The main
band of showers/thunderstorms should move south/east of the
region by afternoon. However, lingering upper level energy and a
possible weak reinforcing cold front may trigger an additional
shower or thunderstorm in the afternoon, especially across the
eastern Catskills into the mid Hudson Valley. It should
gradually become less humid in the afternoon, with late day high
temperatures ranging from the lower/mid 70s across higher
elevations of the Adirondacks, to the lower/mid 80s across
valley areas within the mid Hudson Valley.

Saturday night, generally fair conditions, after any isolated
evening showers dissipate. It should be cooler, with low
temperatures mainly in the 50s.

Sunday-Sunday night, a couple of strong yet compact upper level
impulses look to track across the region during Sunday. Strong
dynamical forcing associated with these impulses could lead to
at least isolated-scattered showers/thunderstorms, although the
areas which may be affected overall could remain limited since
these systems are fairly compact. Would not rule out some gusty
winds/hail with any thunderstorms given fairly low wet bulb zero
levels and strong winds aloft, even though the tops of any
convection may remain relatively shallow/low topped. High
temperatures should reach the mid/upper 70s in valleys, with
mainly 60s across higher terrain. After any isolated convection
dissipates Sunday evening, expect clear to partly cloudy skies
to remain, with temperatures cooling into the lower/mid 50s for
many areas, with perhaps some 40s across portions of the
Adirondacks and higher terrain across western New England.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The extended forecast will be dominated by a mean longwave mid and
upper level trough over the eastern CONUS into the middle of the
week.  Cool and unsettled weather is expected into Wednesday for
early summer.  Some ridging may briefly build into the the Northeast
by Thursday.

Mon-Mon Night...A deepening and amplifying H500 long-wave trough
will be setting up over the Great Lakes Region, OH Valley into the
Northeast.  A series of short-wave troughs will be impacting the
forecast area migrating through the mid and upper level trough.
Heights will be falling across the region with a cold front
initially descending southward from the St Lawrence River Valley,
but will likely lift north late in the day ahead of the short-wave
trough. The 12Z GFS continues to show modest amounts of instability.
A chance of showers with a slight chc of thunderstorms was kept in
the forecast during the day.  Highs will be in the upper 60s to mid
70s in most of the valley areas with upper 50s to upper 60s over the
higher terrain in the cool cyclonic flow.  The showers will become
isolated to scattered at night with the loss of the diurnal heating
with lows in the upper 40s to mid 50s across the region, as H850
temps will be about 1 to 2 standard deviations below normal
according the latest 12Z GEFS.

Tue-Tue Night...The latest GFS/ECMWF/CAN GGEM have a stronger short-
wave embedded in the long-wave trough impacting the region on TUE.
At the sfc, a wave of low pressure will be lifting north of the
region towards the St Lawrence River Valley with a cold front moving
through in the late morning into the afternoon.  The cyclonic
vorticity advection with some thermal advection will generate enough
synoptic lift for showers likely especially from the Capital Region
north, with high chc pops to the south.  The amount of heating and
sfc destabilization is still uncertain, but there could be enough
instability with SBCAPEs in the 500-1000 J/kg for at least a slight
chc of thunderstorms in afternoon. High temps will be similar to MON
with 60s to mid 70s across the region which is about 5-10 degrees
below normal.

Wed-Thu...Much of eastern NY and western New England will still be
under the influence of mid and upper level cyclonic flow with the
trough axis attempting to move downstream.  With the cold pool aloft
and weak impulses rotating around the upper low, then some
instability showers are possible across most of the region. A little
more sunshine before the pop-up showers will allow for highs in the
mid 60s to lower 70s over the higher terrain, and mid and upper 70s
in the valley locations.  There are some signs of ridging building
in from the south and west Wed night-THU with heights rising across
the region based on the 12Z EC and the WPC guidance.  The GFS wants
to the close the upper low over eastern New England with with N/NW
flow isolated-sct showers over the higher terrain. We trended WED
night dry, and based on a blended model approach we kept a slight
chc of showers in the valley areas in the grids during the day, and
a very low chc over the southern Adirondacks, southern Greens,
northern Catskills, and the western Mohawk Valley.  Again, this day
is trending drier if the 12Z EC does not close the upper low off
like the latest 12Z GFS.

Overall, temps look below normal in the long term with pcpn normal
to above normal.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
A warm front will continue to move/lift across region early
this morning. With its passage a humid and warm airmass will be
ushered in. With the area in the warm sector and short waves
moving through flow there will be rounds of convection through
the TAF period. It is a tough forecast to determine the timing
at the individual TAF sites. Have addressed chances with TEMPO
and PROB30 groups in TAFs. Mainly VFR conditions are expected
through much of the day; MVFR conditions will occur with
convection with brief IFR possible. Widespread MVFR conditions
are expected to develop by late in the day as heights begin to
fall as the approaching trough deepens to our west.

A calm to very light southerly flow expected to for the overnight.
Southerly winds will increase to 10 to 15 knots with gusts in
the teens to about 25 knots. The flow is expected to shift more
to the southwest and decrease some in the evening.

Winds stronger in and near thunderstorms.

Outlook...

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

&&

.FIRE WEATHER...
Warmer and more humid conditions will return tonight into
Friday, along with increasing chances for showers and
thunderstorms, some of which may produce locally heavy rainfall.
The showers and thunderstorms should continue Friday night,
before gradually tapering off Saturday as a cold front moves
through and south of the region. Another upper level
disturbance could trigger a passing shower or thunderstorm
Sunday.

Relative humidity values are expected to increase to between 80
and 100 percent tonight. Minimum RH values on Friday will be
around 55 to 70 percent.

Winds will shift into the south tonight at 5-10 mph. Winds on
Friday will be south to southwest and increase to around 10 to
15 mph, with gusts up to 25 mph possible.

Winds will be stronger, and variable in direction in and near
any thunderstorms.

&&

.HYDROLOGY...
A few showers will be possible well west of Albany early this
evening.

More widespread showers and thunderstorms will start to move in
tonight, and especially on Friday as a frontal system gradually
moves across the area. It will become more humid, so there is
the potential for locally heavy rainfall Friday into Friday
evening. Some urban/poor drainage flooding and isolated flash
flooding will be possible with thunderstorms. Basin average
rainfall forecast to be around a half to three quarters of an
inch, with locally higher amounts where persistent
thunderstorms occur. Showers and thunderstorm with locally heavy
downpours may linger into Saturday morning from the Capital
Region and points south and east.

Mainly dry weather then expected for Saturday afternoon with
just a few showers around, with isolated to scattered showers
and thunderstorms possible Sunday into Monday.

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.

&&

.EQUIPMENT...
KGFL airport observation has been intermittently missing again
as technicians continue to troubleshoot. We will continue to
monitor and update this statement as needed.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...KL/BGM/Wasula
NEAR TERM...BGM/Thompson/Wasula
SHORT TERM...KL/JPV
LONG TERM...Wasula
AVIATION...IAA
FIRE WEATHER...KL/JPV
HYDROLOGY...KL/JPV
EQUIPMENT...


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