Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 232335

Area Forecast Discussion
National Weather Service Albany NY
735 PM EDT SAT JUL 23 2016

It will turn cooler and less humid tonight and Sunday, with high
pressure building in. Very warm temperatures, increasing humidity
and chances for showers and thunderstorms return for Monday as a
frontal boundary approaches from the west.


It seems the strengthening upper jet segment and associated upper
divergence, a zone of steeper midlevel lapse rates seen in the
12Z Maniwaki sounding and dry air aloft combined with the
instability due to the hot temperatures contributed to this severe
weather event.

Storms tracking through Schoharie Valley through the Helderbergs
tracking southeast and could have some gusty winds before they
weaken and dissipate through the evening. Storms around and east
of the Capital District into the Berkshires mainly showers now and
continuing to weaken.

Some diurnal cooling beginning and the temperatures in the 90s
with dew points in the 50s to near 60 ahead of the convection in
southern areas still resulting in some instability. Tough to say
how long storms will maintain themselves as they build south but
including showers and thunderstorms to just south of I-90 and will
update if they hold together further. Diurnal cooling and exiting
upper jet segment and exiting upper disturbance should support
weakening and dissipation of the showers and storms before

So, adjusting rain chances, sky cover and temperatures through
this evening based on current data and trends. Once the storms
exit this evening, clearing and some low level drying. Boundary
layer winds do not really diminish much and even though guidance
suggests winds diminishing to near calm...some light winds from
time to time may prevent temperatures from cooling as much as they
could. Lows tonight in the 50s to lower 60s.


Low level ridging tracks through our region Sunday with lots of
sun and light winds. The strong sunshine should help temperatures
to reach the 80s to near 90.

The next upper energy and associated cold front currently in the
upper Mississippi Valley and approaching the Western Great Lakes,
will affect our region Monday and Monday night. Guidance indicates
lots of convective debris and mid/high cloud cover early Monday
with weakening convection reaching the western Mohawk Valley and
southwestern Adirondacks around daybreak Monday. However, west to
west southwest boundary layer flow, which is downslope, and some
flat upper ridging may suggest less convection and convective
debris through Monday morning.

Coverage of cloud cover and timing of the advance of convection
will determine how much we warm Monday. Boundary layer
temperatures are quite warm and again, winds from the west
southwest suggest downslope and perhaps less cloud cover through
Monday morning. So, temperatures should warm well into the 80s to
lower 90s Monday...a little cooler in the western Mohawk valley
and southern Adirondacks, where convection should arrive soonest.

Coverage with the downslope boundary layer flow and relatively
weak low level forcing should be scattered Monday afternoon and
evening. There is a chance once again for severe weather with the
forecasted instability but very similar instability as many severe
weather threats we have had so far this summer. The better low
level forcing may be toward daybreak Tuesday when the thermal
gradient on the leading edge of the cooling and drying tracks
through. So, lingering showers and thunderstorms Monday night.
Dryer weather working into the region Tuesday with just minor
cooling behind the cold front. Highs Tuesday in the 80s to near
90...some upper 70s northern areas.


The upper level pattern should be mainly zonal during much of the
long term portion of the forecast, with several embedded
disturbances translating east within this flow. One of the stronger
disturbances is expected to move east across the Great Lakes/Ohio
Valley region sometime between late Thursday and Saturday. There
remains uncertainty regarding its timing, with the 12Z/23 ECMWF
slightly slower, and the 12Z/23 GFS and GEFS mean slightly faster.

At this time, it appears that above normal temperatures and fair
weather will continue through Wednesday night, with an increasing
chance for showers/thunderstorms for Thursday-Saturday. Most models
seem to be highlighting Friday as the best chance for more
widespread showers/thunderstorms, therefore will indicate slightly
higher pops on Friday. If this wave passes slowly enough and farther
north, enough deep moisture may be entrained into the region to
produce locally heavy yet beneficial rainfall.

Otherwise, temperatures should remain above normal through the
period, although trending closer to normal by Friday-Saturday due to
clouds and possible showers. Humidity levels will likely increase
for Thursday-Saturday. Expect daytime high temperatures to reach the
85-90 in valleys and lower 80s across higher elevations Wednesday
and Thursday, with mainly lower/mid 80s in valleys and 70s across
higher elevations for Friday-Saturday. Overnight lows will mainly be
in the mid/upper 60s in valleys, and upper 50s to lower 60s across
higher elevations, coolest across the highest elevations of the
Adirondacks and southern VT.


Showers exiting KALB and will affect KPSF through about 01Z.
Indicating possible MVFR ceilings and visibilities at KPSF through
01Z. Showers are expected to dissipate before reaching KPOU.
Clearing in all areas through the evening with VFR conditions as
clouds become scattered and visibilities remain VFR. After 05Z-06Z
there could be some fog developing as winds trend to light.
Indicating MVFR visibilities through about 12Z. After 12Z VFR
conditions return with just scattered clouds and good

Winds from the north will diminish to less than 6 kt through this
evening and trend to 3 kt or less between 06Z-12Z. Winds become
north to northwest at 6 kt or less Sunday morning and through the
rest of the day.


Sunday to Sunday Night: No Operational Impact. NO SIG WX.
Monday: Moderate Operational Impact. Scattered SHRA...TSRA.
Monday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.


It will turn cooler and less humid tonight and Sunday, with high
pressure building in. Very warm temperatures, increasing humidity
and chances for showers and thunderstorms return for Monday as a
frontal boundary approaches from the west.

Night time RH values tonight and Sunday night will be between 80
and 100 percent. Minimum daytime RH values will be 30 to 40
percent Monday and 40 to 60 percent Monday.

Northwest winds tonight will decreasing to less than 15 mph.
Winds on Sunday will be northwest at 5 to 10 mph, then shift to
south and southwest at less than 15 mph Sunday night and around 15
mph Monday.


Scattered showers and thunderstorms are expected from the southern
Adirondacks to the Capital District and southern VT through this
evening with brief local downpours. Basin-average rainfall will
be light due to limited coverage.

Dry weather is expected tonight through Sunday, although another
cold front will bring additional chances for showers and
thunderstorms Monday and Monday night.

Dry conditions return for Tuesday and Wednesday as high pressure
builds back into the region.

Flows continue to be below normal for mid to late July at many
locations in the Hydro Service Area, especially our western New
England counties.

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.




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