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fxus61 kaly 191521 
afdaly

Area forecast discussion
National Weather Service Albany New York
1121 am EDT Mon Aug 19 2019

Synopsis...
another hot and humid day is expected today with potential for
strong afternoon/evening thunderstorms, especially from the capital
district south and east. After a dry day Tuesday, showers and
thunderstorms will become likely again on Wednesday. The warmth will
persist through Wednesday before turning drier and milder for the
end of the week.

&&

Near term /through tonight/...
updated at 11 am. A frontal system is working east across
central New York late this morning. Much of the area has seen some
sunshine this morning but a band of clouds will be moving across
the area during the early afternoon along the frontal zone.
MLCAPE values through 11 am are still below 500 j/kg but should
continue to rise into this afternoon as dew points increase
along the frontal zone into the lower 70s and temperatures climb
into the 80s. The 12z Albany sounding shows moderately steep
low- level lapse rates above a shallow surface inversion, then a
weak cap just below 500 mb. We expect enough heating to allow
parcels to get past that cap by early this afternoon. The key to
the forecast today will be how far east the front gets before
showers start to develop along it. The lastest hrrr and NAM nest
forecasts are indicating that the front may get a little
farther east than previous forecasts, which would imply a lower
chance for showers from the capital district westward, with high
chances confined to western New England and the lower and Mid
Hudson valley. In those areas, gusty winds and heavy downpours
could still accompany storms that develop later this afternoon.
The heat advisory will continue for the Hudson Valley today for
highs well into the 80s and dew points near or just above 70.
Previous discussion is below.

As of 640 am, area of showers/isolated thunder over the
southern Adirondacks. Morning showers and thunderstorms should
continue to weaken per cam consensus 12-15z, though it may still
have enough momentum for light showers and perhaps an isolated
thunderstorm to reach the Lake George Saratoga region/capital
district/Berkshires/southern Vermont. In the wake of the wave
associated with this system, models indicate a good subsidence
signal revealed by midlevel warming on forecast soundings. This
should allow for a good period of insolation to boost
temperatures back into the 80s to near 90. Boundary layer will
remain moist with dewpoints likely reaching the mid-60s to low
70s. Will maintain heat advisory for the Hudson Valley from the
capital district south despite recent guidance trending downward
a bit in temperatures. Forecast heat indices are in the 95-100f
range here.

Attention then turns to convective potential during the
afternoon and evening. Aforementioned capping in the wake of the
morning wave will likely hold strong north of the capital
district, so have cut pops down there significantly. From the
capital district south, ample instability is expected to build
beneath the cap, possibly in the 2000-3000 j/kg range. The
question then becomes whether there will be anything to erode
the cap. Strong boundary layer heating will certainly help with
this, but there will also likely be a low-amplitude midlevel
wave (now near kind) tracking through during peak heating. A
surface dewpoint boundary will be associated with this wave. As
a result, consensus with the cams is for showers and
thunderstorms to develop mainly in the 19-00z time frame from
the capital district south and east. Deep shear will be modest
at 20-30kt but sufficient for organized convection, and degree
of aforementioned instability certainly suggests potential for
isolated strong to severe storms with gusty winds and large hail
possible. One source of uncertainty is how fast the forcing for
ascent will progress eastward - a faster progression would
place the storm threat to the east of the forecast area. At this
time it appears there is enough confidence for a marginal risk
of severe weather per latest Storm Prediction Center day 1 outlook. With pwats in
the 1.75 to 2.00 inch range, locally heavy downpours are likely
with any thunderstorm.

Showers and thunderstorms quickly dissipate and move east after
00z. Drier air begins to move in overnight as well, with
dewpoints falling into the mid-50s over the north country, to
the mid-60s over the Mid Hudson valley. Accordingly, lows should
be cooler than recent nights, but still a bit above normal.

&&

Short term /Tuesday through Wednesday night/...
a brief but distinct airmass change is in store for Tuesday as
dewpoints are expected to fall into the 50s to low 60s with
pwats less than 0.75 inches. This will occur as high pressure
aggressively builds into the region in the wake of today's
boundary. It will still be seasonably warm with h850 temps
around 15c. The dry airmass will not last long as return flow
commences as early as Tuesday evening as the high shifts east in
response to troughing upstream. Resulting moisture advection
will allow scattered showers and isolated thunderstorms to
spread from south to north Tuesday night. Lows will mainly be in
the 60s.

On Wednesday, we will be back in a warm and humid airmass once
again with pwats increasing to 1.50-2.00 inches. Tropospheric
wind field will increase in magnitude in response to an
anomalously deep trough approaching the western Great Lakes.
Continued moisture advection along with dynamic lift associated
with low-amplitude waves ahead of the main trough should
contribute to scattered to numerous showers and thunderstorms
through the day. Given the strengthening wind field and rich
boundary layer moisture, there is certainly severe weather and
heavy rainfall potential, although the details remain murky.
Degree of instability will depend on whether any breaks in the
clouds and showers can occur during the morning to early
afternoon hours. Also, models differ with respect to how strong
the wind field is, with the 00z NAM painting an impressive
picture with a 30-35kt 850 mb jet developing. However, it
appears to be the first NAM run this strong, and the GFS/European model (ecmwf)
are weaker (but still with fairly good deep-layer shear). We
will continue to monitor this potential closely. Some lingering
showers and thunderstorms will be possible Wednesday night with
respectable deep moisture lingering and main area of height
falls still off to the west. Mild again with lows mainly in the
60s.

&&

Long term /Thursday through Sunday/...
the transition to an early autumnal airmass will be continuing
through the early portion of the forecast, with mainly dry
conditions and slightly below normal temperatures expected for next
weekend.

There is some uncertainty regarding the main cold frontal passage
timing, as the latest 00z/19 ec suggests a slower frontal passage
with the upper level trough remaining farther west on Thursday,
while the majority of long term guidance suggests a quicker
progression of this system, including the 00z/19 gefs. The 00z/19 ec
was considerably slower than previous cycles, so not much confidence
yet in this slower solution. Will keep some chances for showers on
Thursday, with slight chance for thunder, mainly for the main upper
trough and cold pool passing through. However, should the 00z/19 ec
prove correct, Thursday could be more convectively active across at
least portions of the region.

Still could be some lingering showers into Friday morning as the
upper level trough axis/cold pool passes through. Thereafter, expect
mainly dry conditions next weekend, although will have to watch for
additional upper level energy dropping into the west side of
departing upper level trough. Should this pass far enough west, some
clouds and isolated showers could occur next Saturday across
southern Vermont and perhaps the southeast Adirondacks.

As for temperatures, still somewhat warm and moderately humid
Thursday, especially if the front remains slower, with highs in the
lower/mid 80s in valleys, and 70s most higher elevations. Cooler and
much less humid for Friday-Sunday, with highs mainly 75-80 in
valleys, and mid 60s to lower 70s across higher elevations.
Overnight lows becoming chilly, especially northern areas, where
nights should fall into the 40s, with mainly 50s elsewhere. It is
possible that some sheltered areas of the southern Adirondacks,
southern Vermont and perhaps eastern Catskills fall into the upper 30s
Saturday and Sunday mornings.

&&

Aviation /15z Monday through Friday/...
a cold front will pass across the taf sites this afternoon.
High pressure will then build across the taf sites tonight into
Tuesday.

A band of showers and embedded thunderstorms may impact kgfl through
14z/Mon. Otherwise, expect the low clouds/fog to gradually lift
between 12z-14z/Mon.

Mainly VFR conditions are then expected for this afternoon into
early tonight. However, additional isolated to scattered
thunderstorms may develop along the cold front at kpsf and kpou,
with best chances at these locations between roughly 19z-
23z/Mon. Thunderstorms could briefly impact kalb as they
develop, but chances are a bit lower. If they occur at kalb,
best chance would be slightly earlier, mainly 16z-20z/Mon. A
period of IFR vsbys will be possible within any thunderstorms.

Some patchy ground fog may develop late tonight, mainly after
08z/Tue. Best chance would be kgfl and kpsf. If this develops,
occasional reductions in vsby/cig to IFR/LIFR would be possible.

Winds will trend into the south to southeast at 4-8 knots shortly
after sunrise, then become south to southwest and increase to
5-10 knots by mid morning. Winds will then shift into the
southwest to west this afternoon and increase slightly to 8-12
kt, with some gusts up to 20 knots possible. West to northwest
winds will decrease to 5-10 knots after sunset, and become
light/variable after midnight.

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

Outlook...

Tuesday: low operational impact. No sig weather.
Tuesday night: moderate operational impact. Chance of
rain showers...tsra.
Wednesday: high operational impact. Likely rain showers...tsra.
Wednesday night: moderate operational impact. Chance of
rain showers...tsra.
Thursday: moderate operational impact. Chance of rain showers...tsra.
Thursday night: low operational impact. No sig weather.
Friday: low operational impact. Breezy no sig weather.

&&

Fire weather...
another hot and humid day is expected today with potential for
strong afternoon/evening thunderstorms, especially from the capital
district south and east. A drier airmass will make a brief
appearance for Tuesday as relative humidity values fall into the 40 to 50
percent range in the afternoon with light winds. Scattered to
numerous showers and thunderstorms will return Wednesday.

&&

Hydrology...
another warm and humid day will contribute to scattered showers
and thunderstorms developing in the afternoon and evening,
mainly from the capital district south and east. Any storm will
be capable of locally heavy downpours leading to minor
urban/poor drainage flooding.

After a dry day Tuesday, anomalous moisture returns for
Wednesday. Scattered to numerous showers and thunderstorms are
likely for much of the day. Again, urban/poor drainage flooding
is possible, and isolated flash flooding cannot be ruled out.

It will trend drier for the end of the 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.
New York...heat advisory until 8 PM EDT this evening for nyz049-050-052-
053-059-060-064-065.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...Thompson
near term...mse/Thompson
short term...Thompson

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