Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 240511
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
111 AM EDT Mon Sep 24 2018

.SYNOPSIS...
High pressure will ridge into the area from Eastern Canada and
northern New England bringing fair weather and seasonably cool
temperatures through Monday. A warm front will bring periods of
rain on Tuesday, while a cold front will bring rain showers and
a few thunderstorms on Wednesday. A return to cool and dry
weather is forecast for Thursday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 1220 AM EDT, a cold front was located across the southern
Adirondacks and approaching southern VT. Other than a wind shift
and associated increase in wind speeds, little in the way of
clouds are accompanying the front due to fairly dry air and
subsidence. There was a band of low/mid level clouds across
northern NYS and northern New England, which for the most part
is expected to remain nearly stationary overnight before
drifting back north Monday morning. However, can not rule out
some patchy low clouds brushing northern portions of
Herkimer/Hamilton Cos over the next few hours.

As the front settles southward, there should be an increase in
north/northeast winds through daybreak. In fact, there could be
some gusty winds across Lake George up to 25 mph behind the
front, as low level instability due to the warm lake and
developing cool advection maximizes mixing potential.

Temperatures have already dropped into the upper 30s to lower
40s across portions of the southern Adirondacks, with mid 40s to
lower 50s elsewhere. In some areas, temps may briefly rise as
the winds shift and a brief period of mixing develops, before
temps fall back into the upper 30s/lower 40s toward daybreak
across northern areas, and mostly 40s elsewhere.

Patchy fog/low stratus was noted on latest IR satellite imagery,
particularly valley areas south of I-90 such as the Schoharie
Valley, mid Hudson Valley, SE Catskills and Housatonic Valley in
northwest Litchfield/southern Berkshire Cos. Northern areas may
be less susceptible to fog development compared to last night as
north winds increase through daybreak.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
Dry weather is expected to continue through Monday evening.
High pressure will be anchored across the region through Monday
before sliding east off the New England coast Monday night. A
warm front will be moving into western New York late Monday
night bringing some rainfall to the region which should hold off
until after midnight Monday night. Strong gradient between high
pressure to the east and low pressure to the west leads to
southeasterly LLJ of 50-60kts on Tuesday. This LLJ will likely
enhance rainfall totals in the southeastern Catskills and over
the southeastern foothills of the Adirondacks. There is also a
low potential for some of these winds to mix down in the favored
spots for strong southeasterly winds such as the Bennington, VT
area, North Adams, MA area, the Taconics of New York and across
parts of Herkimer County. Vertical temperature profiles show a
low-level inversion which will hopefully prevent the winds from
mixing down.

There will likely be break in the heavy rain on Tuesday night.
PWATs rise to 1.5 to 2 inches by Tuesday night. Areas of light
rain and drizzle in this muggy air are expected as we will be in
the warm sector and dynamics will be lacking. Rainfall amounts
from late Monday night through Tuesday night should generally
range from an inch to an inch and a half with some 2+ inch
amounts expected in the favored upslope areas.

Highs on Monday and Tuesday will be in the upper 50s to upper
60s. Lows on Monday night in the 40s to mid 50s, and lows on
Tuesday night in the mid 50s to mid 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
At the start of the long term period, a cold front will be making
its way towards the area from the west.  Ahead of the boundary, our
region will be very moist, with PWAT values as high as 1.75 to 2.00
inches.  Model soundings suggest the profile will be rather moist,
so abundant cloud cover looks to be in place, which should limit
surface-based instability.  Will include a slight chc for thunder in
case some elevated instability is in place, but thunder doesn`t look
too widespread considering the limited instability.  Several bands
of showers look to pass through the region ahead of the front, so
locally heavy downpours are possible, esp considering the high
PWATs, and localized hydro issues are possible if heavy shower occur
over repeated areas. Thanks to warm temps aloft, max temps look to
reach the lower to middle 70s for valley areas, although this is
rather low confidence, as the abundant cloud cover may keep temps a
little cooler than currently forecast.

The front should sweep through the area on Wednesday evening, ending
precip and allowing drier air to work into the area from the west.
By Thursday, max temps will only reach into the 60s with dewpoints
in the 40s thanks to a light northwest wind.

The dry weather could be short-lived, although the models are rather
unclear on this.  The GFS and many of the GEFS members suggest a
wave of low pressure may develop along the old frontal boundary and
lift up the eastern seaboard for Thursday night into Friday,
bringing some showers towards our area.  Meanwhile, the ECMWF and
GGEM either don`t show this or have it occurring well south of the
area.  For now, will go with low to slight CHC pops for Thursday
night into Friday and keep temps close to seasonal normals.

As of right now, it looks mainly dry and quiet for most of the
upcoming weekend, although the next northern stream system may be
approaching by late in day Sunday into Sunday night with some
showers, mainly for northern parts of the area. Will continue with
fairly seasonable temps for the last weekend in September.

&&

.AVIATION /05Z MONDAY THROUGH FRIDAY/...
Flying conditions are currently VFR for all sites with sct high
clouds in place. Hi-res model guidance suggests these high
clouds will diminish from north to south across the area
overnight. Although a breeze may stay in place all night at
KALB, KPSF and KGFL, winds should be light or calm for the other
site (KPOU) which may allow for some late-night fog at that
site. Will allow for IFR conditons at KPOU through 08Z as winds
will pick up later tonight which should bring an end to the fog.

After the fog dissipates, VFR conditions are expected today
with just some sct high clouds and a few diurnal cumulus around.
The high clouds may start to increase in coverage by late in
the day as a warm front starts to approach from the south. Light
north-northeast winds in the morning will become southeast
during the day and increase to around 10 kts by late morning or
afternoon.

Outlook...

Monday Night: High Operational Impact. Ocnl SHRA.
Tuesday: High Operational Impact. Definite SHRA.
Tuesday Night: High Operational Impact. Definite SHRA.
Wednesday: High Operational Impact. Definite SHRA...TSRA.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Chance of SHRA.

&&

.FIRE WEATHER...
High pressure will ridge into the area from Eastern Canada and
northern New England bringing fair weather and seasonably cool
temperatures through Monday. A warm front will bring periods of
rain on Tuesday, while a cold front will bring rain showers and
a few thunderstorms on Wednesday. A return to cool and dry
weather is forecast for Thursday.

Relative humidity values will recover to 80 to 100 percent
tonight, and drop to 50 to 65 percent on Monday. Relative
humidity values will recover to 80 to 100 percent again Tuesday
morning

Winds will generally be light and variable at less than 10 mph
this evening. Winds will become northeasterly tonight at 5 to
10 mph and then switch to southeasterly at 5 to 15 mph on
Monday.

&&

.HYDROLOGY...
Fair and seasonably cool weather is expected through Monday.

There is the potential for 1 to 3 inches of rain from late
Monday night into Wednesday evening. A warm front will bring
periods of rain on Tuesday, while a cold front will bring rain
showers and a few thunderstorms on Wednesday afternoon. WPC has
placed much of eastern New York and western New England in a
marginal to slight risk of excessive rainfall Tuesday through
Tuesday night. Periods of heavy rainfall may produce some urban
and poor drainage flooding as well as perhaps some small stream
flooding. Additionally, localized heavy rain is possible on
Wednesday afternoon from thunderstorms as a cold front crosses
the area.

At this time, extended river forecast models show no flooding
is forecast on the main stem rivers, but some half to three
quarter bank full rises are possible.

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...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...SND
NEAR TERM...Frugis/KL
SHORT TERM...SND
LONG TERM...Frugis
AVIATION...Frugis/11
FIRE WEATHER...SND
HYDROLOGY...SND



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