Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 301046
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
646 AM EDT Tue May 30 2017

.SYNOPSIS...
As additional upper level disturbances pass across the region today
through Wednesday, more clouds and showers are expected, with some
thunderstorms also possible. A dry day is finally in store Thursday
as high pressure builds into the region. Temperatures will remain
near to below normal through Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 630 AM EDT, widespread low clouds continue across the
region. Temperatures are fairly uniform, generally in the upper
40s to mid 50s.

Regional radars indicate small clusters of showers and isolated
thunderstorms stretching from south central NYS into north
central PA. This is in association with an embedded shortwave
rotating around the southeast periphery of the upper level low
in the vicinity of the Great Lakes region.

In the lower levels of the atmosphere, a boundary separating
cool, moist air to the east across much of our region, with
warmer air to the west, is located from west central NYS into
PA. The combination of forcing from the approach of the
aforementioned upper level shortwave, and another shortwave
currently located near Chicago, along with low level forcing
from the front, will combine to ignite several rounds of showers
and thunderstorms across central and western NYS/PA this
morning into the afternoon hours.

Low level stability is quite strong across our region due to the
cool/moist air mass in place. Low clouds will also be tough to
dislodge today, so not expecting much of this low level cool air
to be dislodged much, especially given the wind flow below H925
to remain mainly from the south/southeast. There will be
elevated instability with steepening mid level lapse rates, as
well as strong 0-6 km shear of 40-50+ KT, mainly across
northern/western areas.

Based on current thinking, it appears that convection will
ignite across west/central NYS and PA, where more breaks in the
clouds and greater surface destabilization is expected. There is
a possibility that thunderstorms may organize in these areas
into faster moving clusters, containing strong wind gusts.
However, as they advance into western areas of our area, they
should weaken, due to the deepening low level stable layer they
encounter. There could be some lingering strong wind gusts
reaching the surface in some western areas before storms weaken
sufficiently, hence a marginal risk for severe thunderstorms,
mainly for isolated damaging wind gusts, exists for areas from
the Capital Region and points N and W.

Trends will need to be closely watched, however, as some surface
destabilization could occur across portions of the western
Mohawk Valley, Adirondacks, and perhaps the Schoharie Valley if
some breaks in the clouds develop this afternoon, allowing the
threat for stronger thunderstorms to expand farther east.

Will also have to watch for possible training of any convection
this afternoon across portions of the Mohawk Valley/southwest
Adirondacks, which could enhance locally heavy rainfall.

It should be noted that the overall structure of the
closed/upper level low north of the Great Lakes is somewhat
similar to a neutrally tilted `Type B` as examined in CSTAR III
research, which is associated with increased severe weather
across the northeast states, based on pattern recognition.

Have sided with the cooler side of guidance due to the
expectation for considerable cloud cover through the day, with
max temps reaching the lower/mid 60s for most areas, except only
upper 50s across the Berkshires and higher peaks of the southern
Greens, eastern Catskills, with slightly warmer temps, closer to
70, across portions of the western Mohawk Valley and Schoharie
Valley.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Tonight, ongoing convection should continue to weaken as it
translates southeast into the region. Expect mainly cloudy skies
later tonight, with low temperatures mainly in the lower/mid
50s.

Wednesday, as the wind flow below H925 becomes more southwest,
there appears to be a better chance for some clearing to occur
due to some downsloping off the Catskills. This should lead to
greater surface based destabilization to occur, before another
shortwave moves east/northeast across the region in the
afternoon. With greater instability potential, and strong winds
persisting aloft, especially from the I-90 corridor northward,
it appears that the potential for strong thunderstorms, if not
severe, will be greater Wednesday afternoon. SPC has placed much
of the region in marginal risk for Wednesday, and would not be
surprised if at least portions of the area are upgraded to
slight risk with subsequent updates. In addition to strong wind
gusts, with wet bulb zero heights lowering to 7000-8500 FT AGL,
hail could occur with any stronger/deeper convection that
develops. Have therefore included mention of hail/gusty winds
for areas mainly near and north of I-90. Coverage of
showers/storms may be somewhat scattered, especially south of
I-90 which will be further removed from overall forcing and
stronger winds aloft. Temperatures are expected to reach the
lower/mid 70s in valleys, with 60s across higher terrain
Wednesday afternoon.

Wednesday night, any lingering showers/thunderstorms should
taper off by midnight, with partly cloudy skies expected for the
remainder of the night. Some patchy fog could form. It will
remain cool, with lows mainly in the mid 40s to lower/mid 50s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Dry weather expected Thursday before the approach of more upper
energy and a cold front timed for later Friday and Friday night.
Highs Thursday in the mid 60s to lower 70s but around 60 to lower
60s higher terrain.

Sources of guidance not in exact agreement with timing of a cold
front later Friday and Friday night.  So, including scattered
showers and thunderstorms Friday afternoon and night.  Highs Friday
in the 70s but mid 60s higher terrain.

Beyond Friday more disagreements in sources of guidance and
ensembles.  There is a general agreement for a dry period Saturday
before potentially stronger upper energy approaches from southern
Canada and the Great lakes later in the weekend and the beginning of
next week. Highs Saturday in the upper 60s to mid 70s but around 60
to lower 60s higher terrain.

General consensus from sources of guidance and ensembles for rain
chances Sunday and Monday but big differences in strength and track
of upper energy as it affects our region. So, just indicating
scattered showers Sunday and Monday until the areal coverage and
intensity of rain can be determined as we get closer.

Whether we get a little rain or locally heavy rain, the near to
below normal temperatures with general cloudiness and wetter than
normal weather looks to continue.  Highs Sunday in the mid 60s to
lower 70s but lower 60s higher terrain. Highs Monday in the 60s with
lower 60s north and upper 60s south.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Expect mainly MVFR Cigs to continue through the day, although
embedded IFR conditions will be possible this morning,
especially KPSF. Several waves of showers and possibly embedded
thunderstorms are expected to translate east/northeast, and
affect KGFL/KALB and possibly KPSF between late morning and
early evening. Some gusty winds could occur in any stronger
thunderstorms.

For tonight, after any showers/thunderstorms taper off in the
evening, expect mainly MVFR/IFR conditions, mainly for Cigs. The
best chance for IFR/LIFR conditions will be after 08Z/Wed.

South to southeast winds 8-12 KT by early Tuesday afternoon.
Some stronger gusts, possibly to 20-25+ KT, could occur at KALB
in the afternoon. South to southeast winds should average 5-10
KT Tuesday night.

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

Outlook...

Wednesday Night: Moderate Operational Impact. Scattered SHRA...TSRA.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Moderate Operational Impact. Scattered SHRA...TSRA.
Friday Night: Moderate Operational Impact. Scattered SHRA.
Saturday: Low Operational Impact. Isolated SHRA.

&&

.FIRE WEATHER...
As additional upper level disturbances pass across the region today
through Wednesday, more clouds and showers are expected, with some
thunderstorms also possible. A dry day is finally in store Thursday
as high pressure builds into the region. Temperatures will remain
near to below normal through Thursday.

&&

.HYDROLOGY...
Radar estimates and spotter observations suggest 0.25" to up to
1.00" of rain fell Monday, with heaviest amounts over Herkimer
County. Additional periods of showers and thunderstorms are
likely today through Wednesday. Rainfall totals are generally
expected to remain at a half inch or below, but locally a half
inch to an inch is possible over the Mohawk Valley and Western
Adirondacks. Showers and thunderstorms are likely yet again on
Wednesday, with an additional 0.25-0.75" expected. Widespread
flooding is not expected, although some minor urban, small
stream, and poor drainage flooding cannot be ruled out
especially if storms train over the same area.

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...
The ASOS at the Pittsfield Municipal Airport, MA and Glens
Falls, NY continue to experience outages with hourly METARS
occasionally or continuously missing. This will persist until
communications are fully restored.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...IAA/KL/Thompson
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...NAS
AVIATION...IAA/KL
FIRE WEATHER...KL/Thompson
HYDROLOGY...KL/Thompson
EQUIPMENT...



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