Albany, NY WFO Forecast Discussion

Forecast Discussion for ALY NWS Office
000
FXUS61 KALY 181025
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
625 AM EDT Fri Jun 18 2021

.SYNOPSIS...
Sunshine this morning will give way to clouds this afternoon
with an increased chance for some showers, mainly north and west
of Albany. A series of disturbances will pass across the region
tonight through Saturday with scattered showers and a few
thunderstorms. Some storms may be strong to severe on Saturday.
Drier weather looks to return on Sunday but it will be warm.
Rain chances return early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
.UPDATE...
As of 625 AM EDT, forecast remains on track today. Cirrus clouds
are beginning to spread in from the west with a gradual increase
in clouds expected throughout the day. Latest CAMS still suggest
some light rain showers are possible this afternoon for areas
mainly north and west of Albany. Just some minor updates to
pops in the event sprinkles do occur for areas farther south and
east this afternoon and evening. It is a cool/chilly start for
some with temperatures ranging from 38 in Old Forge to 56 at
Duanesburg.

Previous Discussion:
We will start out today dry with sunshine and some passing high
clouds with the upper-level ridge and surface high pressure
system positioned over the region. Over the course of the day,
the surface high will push to our east while the ridge flattens
and an upper-level shortwave approaches from the west. This will
lead to a gradual increase in clouds. A weakening MCS, located
across the Upper Great Lakes this morning and within the
shortwave, will push eastward across our region this afternoon
and could bring some light rain showers to areas mainly north
and west of Albany. Guidance shows little if any instability
across the region during the afternoon, so thunder is not
expected with this activity. The gradual increase in low- level
moisture will send dew points into the 50s by the afternoon.
High temperatures will range from the lower 70s across the
higher terrain to the lower 80s along the Hudson Valley.

Tonight, the shortwave will depart to the east, but additional
shower activity will be possible, mainly dynamically driven by
increasing low-level moisture, divergent flow in the mid-levels and
an approaching 80-110 kt upper-level jet. There is some model
uncertainty regarding coverage but at least some scattered activity
will be possible. Instability will increase but remain low
(generally under 300 J/kg) so expecting only isolated coverage of
thunderstorms. With the clouds and additional moisture, it will be a
milder night with lows in the upper 50s to mid-60s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Uncertainty remains high on Saturday as an upper-level trough
moves into the region. The latest guidance has trended warmer
but not as humid (suggesting the atmosphere can mix itself out
during the day). This could lead to weaker instability than
previously thought. However, shear will remain high so
organized showers and thunderstorms remain possible (a common
low CAPE/high shear environment). The question still remains the
amount of coverage and instability as CAMS all show various
solutions with inconsistencies among each model run. Will
continue to run with chance pops and wording of `scattered
showers` with at least isolated thunderstorm potential. The
latest SPC forecast places the entire region in a marginal risk
for severe weather with some of the strongest storms capable of
producing hail and damaging winds. Trends will continue to be
monitored. Highs Saturday look to reach the lower 70s to mid-
80s. Activity should gradually wind down Saturday night with
lows in the 50s to lower 60s.

Weak ridging builds in for Sunday with continued warm and
slightly humid conditions. Guidance suggests some isolated
shower or thunderstorm activity may be possible during the
afternoon, mainly across the higher terrain, but we will keep
the forecast dry for this update as there is a lack of a trigger
and we anticipate instability to remain rather weak. High
temperatures look to reach the mid-70s across the higher terrain
to the mid- to upper 80s in the valleys. Sunday night looks to
remain dry as well with lows in the upper 50s to mid-60s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Mean upper troughing and upper energy gradually builds east as
tropical moisture tracks just south of our region. Increasing warm
advection and low level moisture advection through Monday with
instability and the axis of deepest moisture most likely in western
NY/PA through the afternoon Monday, building east through Monday
night into Tuesday morning.

So, considerable sun through Monday afternoon, with some isolated to
scattered thunderstorms perhaps just reaching the Schoharie valley,
western Mohawk Valley and southwestern Adirondacks. Highs Monday in
the 80s with near 90 Hudson Valley and NW CT and lower 80s higher
terrain.

Diurnal cooling Monday night with stabilization of the atmosphere
and weakening low level forcing Monday night suggests just scattered
showers and isolated thunderstorms building east through our region
Monday night with humid conditions. Upper jet structure evolves in a
potentially troubling manner, with our region in the right entrance
region of a potentially very strong upper jet and the 500 hPa having
somewhat of a negative tilt. Considering the moisture and
instability ahead of the cold front, will have to watch for strong
thunderstorms and locally quite heavy rain.

The problem is that there are still considerable disagreements in
sources of guidance/ensembles as to the timing of the cold front
Tuesday.  The timing will determine what areas can warm enough to
maximize destabilization and what areas will see the axis of maximum
moisture within that destabilization zone along and ahead of the
cold front.  Quite a tight boundary layer thermal and moisture
boundary will provide enhanced low level forcing, independent of the
instability and moisture, adding to the potential for the strong
thunderstorms and heavy rain potential.

So, siding with slower movement to the front, which a slight
majority of guidance/ensembles suggest. This would suggest
morning showers and thunderstorms in western areas and a period
of mixed clouds and sun in eastern areas with convective debris
and a few morning showers. Temperatures possible not reaching 70
Tuesday in western areas as the showers and isolated
thunderstorms will affect those areas in the morning along with
the passage of the cold front. Eastern areas should warm to
around 80 to lower 80s with a few mid 80s in the mid Hudson
Valley. Indicating showers likely and scattered thunderstorms
most everywhere Tuesday afternoon. Any scattered showers and
storms should end Tuesday evening and night and cold advection
spreads across the region.

Dry weather Wednesday and Thursday with highs in the 70s and cooler
in higher terrain.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A ridge of high pressure at the surface and aloft will build east of
our region through this evening. Slow and gradual increase in low
level moisture and temperatures reaching dew points around daybreak
could result in some intervals of fog between 08Z-12Z at KGFL and
KPSF.

Otherwise, VFR at all TAF sites through this evening, with high
clouds increasing this afternoon and evening. As a warm front
approaches, some scattered showers could reach the TAF sites this
evening, but quite scattered. Including PROB30 for showers with MVFR
visibilities and VFR ceilings this evening.

Winds will be light and variable to calm through mid morning. A
southerly flow will develop mid morning and continue through the
afternoon at 5 to 10 Kt. Winds will diminish below 6 Kt this
evening.

Outlook...

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

&&

.FIRE WEATHER...
Sunshine this morning will give way to clouds this afternoon
with an increased chance for some showers, mainly north and west
of Albany. A series of disturbances will pass across the region
tonight through Saturday with scattered showers and a few
thunderstorms. Some storms may be strong to severe on Saturday.
Drier weather looks to return on Sunday but it will be warm.
Rain chances return early next week.

Minimum RH values today will generally be between 35 and 50
percent. RH will increase to around 85 to 100 percent tonight.
RH values will be a bit elevated on Saturday, in the 40 to 60
percent range.

Wind will become south to southwesterly through tonight at 8 to
16 mph with some higher gusts possible, especially along the
Hudson Valley. Wind on Saturday will be out of the west-
southwest at 10-20 mph.

&&

.HYDROLOGY...
Sunshine this morning will give way to clouds this afternoon
with an increased chance for some showers, mainly north and west
of Albany. A series of disturbances will pass across the region
tonight through Saturday with scattered showers and a few
thunderstorms. Widespread hydro issues are not expected, but
local downpours are possible and may lead to ponding of water
and minor river rises in some areas. Sunday looks to be drier
but rain chances increase again early next week.

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...JPV/Rathbun
NEAR TERM...Rathbun
SHORT TERM...Rathbun
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...Rathbun
HYDROLOGY...JPV/Rathbun

NWS ALY Office Area Forecast Discussion