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FXUS61 KALY 090059
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
859 PM EDT Wed Jul 8 2020

.SYNOPSIS...
High pressure will build in from the Ohio Valley tonight
with muggy conditions and patchy to areas of fog. Hot and humid
conditions are expected on Thursday. A system moving up the coast
is expected to bring widespread rainfall later Friday and Friday
night, possibly lingering into Saturday.

&&

.NEAR TERM /THROUGH THURSDAY/...
A Heat Advisory remains in effect 12PM to 8PM Thursday.

As of 858 PM EDT...The Severe Thunderstorm Watch 343 that
included southern VT is canceled. The thunderstorms have
diminished and just a few showers are lingering over the
northern Adirondacks and parts of the southern Greens. The
short-wave has moved east of the region and lots of mid and
upper level dry air can be seen on the water vapor imagery. High
pressure will be building in from the Ohio Valley and West
Virginia. The skies will become mostly clear/clear with patchy
to areas of fog forming and some low stratus due to the recently
wet ground from the convection. The winds will also go light to
calm. We expanded the fog coverage with the update. It will be
quite mild and muggy tonight with lows in the mid 60s to around
70F in the valleys and lower to mid 60s over the higher terrain.

Thursday, expect a hot day with partly to mostly sunny skies.
850 mb temps appear to be around 18C, and although forecast
sounding suggest we may not mix quite that high, it still
supports highs in the mid-80s to mid-90s. Combined with
dewpoints in the upper 60s to low 70s, this will yield maximum
heat indices in the mid to upper 90s in the Hudson and Mohawk
Valleys where Heat Advisories remain in effect. No changes
planned to the headlines at this time. CAMs suggest a few
isolated storms may fire over the higher terrain of western New
England, eastern Catskills, and perhaps the southern Adirondacks
due to terrain circulations. Deep layer moisture will be much
less than today, with PWATs generally 1-1.50 inches, and due to
weak forcing, expect things to remain fairly isolated.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Focus in the short term will be on a northward moving low with
copious tropical moisture. NHC gives this low a 70% chance of
tropical development within 48 hours. Regardless, it appears the
main threat for our area would be the potential for heavy
rainfall, and these impacts would be the same regardless of
whether or not the storm becomes named. Thursday night, expect
another mild and muggy night with high clouds gradually
advancing ahead of this system. Model agreement in the timing
and track of this system is not great at this point. Per the WPC
Model Diagnostic Discussion, the deterministic NAM/GFS are not
preferred, and instead the ECMWF/GEFS/CMC is preferred. This
would track the system northward roughly along the NJ shore
Friday night before getting absorbed by an incoming midlatitude
trough from the west on Saturday as the low center moves into
southern New England. With this track, expect a period of
moderate to heavy rainfall as tropical moisture with forecast
PWATs in excess of 2 inches moves into our area. Flooding
potential is a bit less certain owing to track and timing
uncertainties, along with antecedent dry conditions. See hydro
discussion below for more details.

Friday, will gradually introduce PoPs from south to north since,
despite the preferred slower model solutions, there could be
some rainfall along the outer fringes of the system especially
reaching areas south of Albany. Outside of this rainfall and
clouds, another very warm to hot day is expected, with some of
the warmest temperatures from Albany northward. Will trend PoPs
upward Friday night and linger likely PoPs into Saturday which,
at this point, is when we expect the best coverage of rainfall.
Some embedded thunder is possible as Showalter indices approach
0.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Through the first few days of the extended period, our region will
remain under the influence of a broad upper level trough. A large
closed off upper level low will be diving from the Great Lakes
towards the Northeast for Monday into Tuesday. By Wednesday, upper
level heights will be building, with models hinting as some very
high heights and warm temps aloft for late in the week.

With the upper level trough overhead, there will be a chance for
showers and thunderstorms from Saturday night through Tuesday. The
best chance will likely be during the afternoon and evening hours,
with Monday at this point expected to be the most active day thanks
to the nearby upper level low. Despite the chance for precip, temps
aloft are still fairly warm, so daytime highs will be well into the
80s each day. With dewpoints in the upper 60s to near 70, it will
feel very muggy. Overnight lows will remain mild and sticky, with
low mainly in the mid to upper 60s.

With the ridge building into the area, the chance for showers and
thunderstorms should be much lower by Wednesday into Thursday. Highs
on Wednesday should be near 90 (or perhaps higher) in valley areas,
with humidity levels remaining very high. Heat index values have a
chance to reach near advisory criteria for the middle to latter
portion of the week.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
High pressure will build in from the Ohio Valley and Mid
Atlantic States tonight with the isolated to scattered showers
and thunderstorms ending. The sfc high will be in control during
the day with just an isolated threat for a showers or
thunderstorms over the higher terrain outside the Hudson River
Valley.

A warm and humid air mass will be cover the region tonight, and
all the TAF sites received some rainfall from the showers and
thunderstorms. The recent wet ground and abundance of low-level
moisture will allow for patchy to areas of mist or fog to form
quickly between 03Z-06Z/THU. Also low stratus clouds will likely
form in the IFR/MVFR range. We have KPOU/KGFL/KPSF/KALB falling
into the IFR or LIFR range with cigs/vsbys between 03Z-06Z/THU.
Fairly widespread IFR/LIFR mist/fog and low stratus will
continue through the early morning hours.

A gradual improvement to MVFR cigs/vsbys is expected between
12Z-16Z/THU with the mist/fog and stratus dissipating. The
stratus may hang on the longest at KALB/KGFL/KPOU with cigs
1.5-2.5 kft AGL until 16Z-17Z/THU and later TAF issuances can
fine tune. Expect VFR conditions thereafter with few-sct cumulus
and sct-bkn cirrus. An isolated thunderstorm is possible at
KPSF after 20Z/THU and we placed a VCSH group there.

The winds will be south to southeast at 4-8 kts early this
evening and then will become light to calm shortly before or
just after midnight. The winds will be light from the south to
southwest at 3-6 kts during the late morning into the afternoon.

Outlook...

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

&&

.FIRE WEATHER...
A hot day is in store Thursday with minimum RH values in the 40
to 50 percent range along with light southerly winds. RH values
will rebound to 90-100 percent overnight. A low pressure system
is expected to bring rainfall later Friday into Saturday. Many
areas will at least start out the day dry on Friday before rain
moves in from south to north. Another warm and humid day is
expected Friday with RH values only falling to 45-65 percent
(lowest north of Albany) along with light to moderate southeast
winds.

&&

.HYDROLOGY...
Locally heavy rainfall in showers and thunderstorms remains
possible through this evening mainly along and south of the
Route 7/I-88 corridors into southern Vermont.

It will be mainly dry on Thursday aside from some isolated high
terrain storms.

A moisture-rich system will move up the coast Friday into the
weekend. This system has the potential to bring moderate to
heavy rain to the region later Friday into Saturday. This system
is forecast to have precipitable water values in excess of two
inches, which is +2 to +3 standard deviations. Moderate to
locally heavy rainfall will be possible with this system,
although there is uncertainty on the location of the heaviest
rainfall. It is also uncertain whether the heavy rainfall will
result in flooding due to antecedent dry conditions. At the
moment, MMEFS does not indicate any flooding on area rivers.
Some shorter-fused urban/small stream flooding or flash flooding
cannot be ruled out.

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...Heat Advisory from noon to 8 PM EDT Thursday for NYZ038-040-
041-043-048>050-052-053-059-060-064-065-083-084.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Thompson/Wasula
NEAR TERM...Thompson/Wasula
SHORT TERM...Thompson
LONG TERM...Frugis
AVIATION...Wasula
FIRE WEATHER...Thompson
HYDROLOGY...Thompson
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