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fxus61 kaly 232356 
afdaly

Area forecast discussion
National Weather Service Albany New York
756 PM EDT Fri Jun 23 2017

Synopsis...
warm and humid air mass will continue into tonight ahead of a
cold front, along with occasional showers and thunderstorms,
some of which could produce locally heavy rainfall. Saturday
will see a drying trend behind a cold frontal passage.
Seasonable temperatures return on Sunday, with perhaps a few
passing showers or a thunderstorm over mainly northern portions
of the forecast area.

&&

Near term /until 6 am Saturday morning/...
as of 651 PM EDT...some slight changes to the forecast based on
the radar trends. The shower and isolated thunderstorm activity
has diminished in the last few hours, but we are seeing and
increase in the showers and isolated thunderstorms ahead of the
cold front moving across the eastern Great Lakes region and into
western New York. Also, an area of showers and thunderstorms with
locally heavy rainfall is approaching from eastern PA and north-
central New Jersey. Some of these showers and thunderstorms may get
into the southern portion of the forecast area /Mid-Hudson
valley and northwest CT/ between 00z and 02z. We retooled the pops
based on the radar trends, and continued to increase to likely
values before midnight. The latest 3-km hrrr trends still seem
to be over doing potential convection from the capital region
south and east. We will continue to monitor the heavy rain
potential. The upper jet dynamics do get better tonight with the
approaching cold front.

Previous near term...

Later tonight, overall forcing will increase, as a cold front
approaches from the west, and an upper level jet across the
Great Lakes begins to shift farther S/E, placing the right
entrance region a bit closer to our region. In addition, a
powerful shortwave, currently noted on WV satellite imagery
moving into the Midwest, continues to move east. The
combination of increased forcing, along with plenty of deep
moisture and additional forcing from the remnants of Cindy
should allow showers and embedded thunderstorms to increase in
areal coverage after midnight. Some hi-res models suggest a band
of training heavy rain elements may occur, especially just S/east
of the capital region. Trends will need to be watched closely
tonight in case a short-fused Flash Flood Watch needs to be
issued. At the very least, can not rule out isolated flash
flooding, and certainly areas of urban/poor drainage flooding.

The Storm Prediction Center continues to have a marginal risk
for severe thunderstorms tonight. However, with waning
instability, this potential looks to be isolated at best, with
perhaps damaging wind gusts from a rogue wet microburst, mainly
this evening.

It will remain warm and humid, with lows mainly in the mid 60s
to lower 70s.

&&

Short term /6 am Saturday morning through Monday night/...
Saturday, the aforementioned strong shortwave will be crossing
through the region during the morning hours. Rain and/or showers
will likely persist well into the mid morning hours from the
Albany/Saratoga/Lake George region and points south and east.
Some locally heavy rain will be possible, especially from the
Mid Hudson valley northeast into northwest CT and possibly the southern
Berkshires. The rain should finally moves S/east of the region by
early afternoon, with clearing expected. However, another upper
level impulse could trigger isolated showers to develop later in
the afternoon, especially across the eastern Catskills. It will
become quite breezy by Saturday afternoon, with wind gusts
possibly reaching 25-30 mph. Afternoon highs should reach the
mid 70s to around 80, except 60s to lower 70s across some higher
elevations of the southern Adirondacks and southern VT, with
some lower/mid 80s possible across portions of the Mid Hudson
valley where afternoon sunshine and a downsloping flow may
enhance warming.

Saturday night, generally clear to partly cloudy and cooler,
with lows in the 50s to lower 60s.

Sunday, a strong upper level disturbance is expected to approach
in the afternoon. It appears that the best forcing and
associated shallow instability will be mainly across northern
areas, north of I-90. Expect scattered showers and isolated
thunderstorms to develop by afternoon in these areas. With
strong winds anomalously cold air aloft, some gusty winds and
small hail could occur in any deeper convective elements. Highs
should mainly reach 75-80 in valley areas, with 60s to lower 70s
across higher terrain.

Sunday night, any evening isolated/scattered convection should
decrease in the evening hours, although could persist across the
southern Adirondacks well into the night which will be in
closer proximity to the main upper level forcing. Otherwise, it
should be cool, with lows mainly in the 50s.

Monday-Monday night, another fast moving disturbance may trigger
isolated to scattered showers/storms Monday afternoon/evening.
Again, with fairly strong winds and cold air aloft, some small
hail/gusty winds could occur with any deeper convective
elements, despite fairly isolated/scattered coverage. Highs
should reach the 60s and 70s, with lows mainly in the 50s,
except for some 40s across portions of the southern
Adirondacks/southern Vermont.

&&

Long term /Tuesday through Friday/...
the extended period begins with a shortwave trough from the corn
belt states digging eastward into the northeast. For the morning
hours, included slight chance probability of precipitation for the lower half of the County Warning Area and
chance pops for the upper half due to southwest flow aloft and positive vorticity advection.
Increased probability of precipitation for the afternoon as guidance is in agreement that
the trough axis passes through during this time. While daytime highs
will be about 5 - 10 degrees below normal only in the upper 60s/low
70s, included thunderstorm potential due to cool pool aloft, daytime
heating that could lead to some instability (200 - 800 j/kg modeled
cape) and impressive upper level dynamics (100-110knots 300mb jet
over new england).

The trough should exit from west to east Tuesday night with cool
Canadian air filtering into the region behind it. In fact, as skies
clear overnight and winds stay light, radiational cooling should
allow overnight lows Tuesday night to tumble into the low 50s for
the majority of the County Warning Area and even into the 40s in the Adirondacks
(again about 5 - 10 degrees below normal).

Ridging tries to build in from the southwest on Wednesday as high
pressure noses in from the Tennessee Valley but the high's center
should stay well to our south as strong westerly winds within zonal
flow aloft quickly return over the northeast. Either way, we should
stay mainly dry on Wednesday with highs warming back into the mid
upper 70s. The next system looks to be in the Great Lakes/southern
Canadian Thursday/Friday with its associated warm front
potentially reaching our region. Given this is nearly a week
away, it's no surprise models differ on timing but the Euro and
GFS both suggest the warm front could stall somewhere in our
northern cwa, presenting US with multiple forecast challenges.
Thus did not differ much from the super blend for this period.

&&

Aviation /00z Saturday through Wednesday/...
a cold front will slowly approach from the west tonight with
showers and isolated thunderstorms ahead of it with MVFR/IFR
conditions for kgfl/kalb/kpou/kpsf. The front will move south
and east of the region Saturday morning with an improvement to
VFR conditions, as a drier air mass builds in.

Showers and thunderstorms will increase across eastern New York and
western New England between 00z-04z from the south/southwest to
the north/northeast. The best chance of a thunderstorm will be
for kpou/kpsf and a tempo group was used to highlight this
potential. Less instability is further north and thunderstorms
have been left out of the kalb/kgfl tafs. Showers will become
widespread before midnight, and continue until 12z-15z from kalb
north and west, and then diminish in the wake of the front for
kpsf/kpou between 15z-18z. Cigs/vsbys will lower to MVFR/IFR
conditions in the showers/isolated thunderstorms overnight. The
best chance of sustained IFR cigs/vsbys will be for kpou/kpsf
between 07z-15z with possibly some brief LIFR cigs at kpsf. A
return to VFR conditions is expected by the late morning into
the afternoon from northwest to southeast for the terminals.
Few-scattered cumulus and/or sct-bkn cirrus may linger in the
afternoon, especially south and east of kalb.

The winds will be from the south to southwest at 5-10 kts
tonight with stronger winds possible with any thunderstorms.
The winds will shift to west to northwest between 11z-14z at
7-12 kts, and increase to 10-15 kts by the late morning and
early afternoon with some gusts in the 20-25 kt range especially
at kalb/kpsf.

Outlook...

Saturday night: no operational impact. No sig weather.
Sunday: moderate operational impact. Scattered rain showers...tsra.
Sunday night: low operational impact. Isolated rain showers.
Monday: moderate operational impact. Scattered rain showers...tsra.
Monday night: low operational impact. Isolated rain showers.
Tuesday: moderate operational impact. Chance of rain showers...tsra.
Tuesday night: no operational impact. No sig weather.
Wednesday: no operational impact. No sig weather.

&&

Fire weather...
wind gusts of 25-30 mph possible Saturday afternoon...

Warm and humid weather will continue into tonight, along with
periodic showers and thunderstorms, some of which could produce
locally heavy rainfall. Saturday will see a drying trend behind
a cold frontal passage. Seasonable temperatures return on
Sunday, with perhaps a few passing showers or a thunderstorm
over mainly northern portions of the forecast area.

Relative humidity values are expected to rise to 90-100 percent tonight, then
fall to 40-50 percent Saturday afternoon.

South to southwest winds this evening of 5-15 mph should shift
into the west toward daybreak at similar speeds. On Saturday,
winds will become west to northwest at 10-20 mph with some gusts
of 25-30 mph possible.

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

&&

Hydrology...
showers and thunderstorms will become more widespread later
tonight as a frontal system gradually moves across the area. It
will become more humid, so there is the potential for locally
heavy rainfall. Some urban/poor drainage flooding and isolated
flash flooding will be possible. Basin average rainfall
forecast to be around a half to three quarters of an inch, but
locally higher amounts will occur in thunderstorms. Showers and
thunderstorms 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
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 observations are coming in and we will continue to
monitor this trend into this evening.

&&

Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...Thompson/wasula
near term...kl/wasula
short term...kl/Thompson
long term...speciale

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