Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 270604
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
204 AM EDT Thu Apr 27 2017

.SYNOPSIS...
As low pressure slowly departs, drizzle will end over the region
this evening into tonight, although it will remain fairly cloudy
with some patches of fog. Once clouds breaks on Thursday morning,
warm temperatures with a partly sunny sky are expected for Thursday
afternoon.  A frontal boundary will bring some passing showers for
Thursday night, with another mild day expected on Friday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 115 am, trapped low-level moisture manifesting itself in
rather expansive, albeit thin, layer of low-level clouds across
most of the CWA. This cloud deck has been expanding westward
slightly over the past few hours, and short-term guidance
suggests it will largely hold firm overnight aside from a few
breaks here or there as flow remains weak. Patchy fog is also a
possibility especially in areas that do see a bit of clearing,
but the low stratus should keep the threat limited in area.
Given current dewpoints and cloud cover, have bumped up
overnight low temps a bit.

Previous discussion...The moist, cyclonic flow associated with
the area of low pressure will continue to keep it fairly cloudy
throughout the region into the overnight hours. Sky cover will
generally be mostly cloudy to overcast tonight. With the moist
low levels, some patches/areas of fog will be possible tonight,
especially in areas where the terrain traps the low-level
moisture in place, as surface temps cool off. With the clouds
overnight, temps will be in the upper 40s to mid 50s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
The closed off upper level low will continue to track away from
the area on Thursday, as it slides to the east of New England.
Meanwhile, a shortwave ridge will move across the area on
Thursday.

Once any morning fog and low clouds break up, skies should be
partly sunny and temperatures will be rather warm on Thursday
with dry conditions. Although 850 hpa temps will be warm and
reach 10 to 13 degrees C, mixing will be limited on Thursday to
about 875 hpa. As a result, max temps in valley areas look to
reach lower to middle 70s, with upper 60s for the high terrain.

The next storm system will be approaching for Thursday night
into Friday morning. The low pressure area will be well west of
the area and passing across the upper Great Lakes and into
western and central Ontario. Meanwhile, the surface cold front
will be approaching the area and running into the upper level
ridge, which will be causing it to weaken. A line of showers
will be along with this front, although they will be diminishing
in coverage and intensity. Have generally gone with chc pops
for Thursday night into early Friday for showers. Some isolated
thunderstorms will be possible as well. Although surface-based
instability looks fairly limited, there could be some elevated
instability in place, so a few rumbles of thunder will be
possible along with some of the rain showers. Lows on Thursday
night look to fall into the 50s.

The front should be through early in the day, allowing for
clearing to occur on Friday morning. Despite being behind the
front, this clearing will allow for another mild day on Friday
afternoon with highs in the upper 60s to upper 70s, with dry
conditions.

After dry weather on Friday evening, a slight chance for showers
will return by late Friday night as the next frontal system
starts to approach with increasing cloud cover. Lows on Friday
night will once again mainly be in the 50s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The extended forecast period continues to be a bit unsettled as
multiple frontal boundaries impact the region this weekend into the
early next week.

Saturday will feature Canadian high pressure slowly sinking into far
Upstate NY with an east-west oriented frontal boundary stalled over
the Capital District Valley. A notable 850mb temperature spread
results across the front with +12-14C in Dutchess and Ulster while
+4-6C sits over Herkimer and Hamilton Counties. This makes for a
tricky and lower confidence temperature forecast as highs will be
contingent on exact frontal placement. For now have gone with
low 80s in the mid - Hudson Valley cooling down to mid 60s for
our northwest CWA. Temperatures are not the only parameter
impacted by the front. Most models suggest an impulse riding
along the boundary between 18z and 00z Saturday which results in
rain and possible t-storms. The 12z NAM, Canadian and GFS are
fairly in line with the boundary stalling across the Capital
District while the ECMWF is an outlier having the front sag
further south into the mid - Hudson Valley. Any isolated to
scattered showers/storms should end quickly Sat night as the
cold front pushes south of our CWA and the Canadian surface high
takes control. This high will usher in cooler temperatures with
overnight lows falling into the 40s with even a few 30s popping
up over the Adirondack Park and southern Greens.

With high pressure in place, Sunday will be fairly pleasant overall
as H500 ridge takes shape off the Mid Atlantic Coast. Clouds will be
on the increase from the west/southwest during the afternoon with a
chance of showers (best chance west of the Hudson River Valley) as
the front from Saturday begins to retreat north as a warm front.
There is also a slight chc of thunderstorms due to weak
elevated instability.  Better chances of showers Sunday night with
the warm front setting up just south and west of the forecast area
over PA. Considering the isentropic lift and moisture convergence, the
boundary may continue the showers into Monday morning.  Highs on
Sunday will generally be in the mid and upper 60s in the valley
areas, and upper 50s to mid 60s over the hills and mountains.  Lows
Sunday night due to wet bulbing will be in the 40s to lower 50s.

Monday into Tuesday...Some uncertainty with the forecast on Monday,
as a strong sfc cyclone moves into the Upper Midwest and western
Great Lakes Region.  The warm front placement is variable in the
deterministic and ensemble guidance.  A blend of the guidance
favored high chc/low likely pops for most of the region with a
chance of afternoon thunderstorms if we get into a warm sector ahead
of the cold front.  Modest amounts of instability are forecasted by
the latest 00Z GFS.  Sfc dewpts do get into the 50s.  The best
convergence with the cold front looks to be late Monday afternoon
into the nighttime period, so we continued high chc and likely pops
for showers and a slight/low chc of thunderstorms.  Highs Monday
were lowered some due to the rain cooled air and clouds possibly
lingering with 60s to lower 70s, as lows will only fall back into
the mid 40s to mid 50s.   The cold front drifts south of the region
Tuesday, but a short-wave pivoting around the H500 upper low south
of James Bay way focus some isolated to scattered showers, as temps
trend back to seasonal normals with highs in the 50s to lower 60s
over the higher terrain, and mid and upper 60s in the valleys.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Low pressure near Long Island will continue to move eastward
this morning. The stacked sfc cyclone will be well east to
southeast of Cape Cod by the late afternoon into the early
evening. A cold front will approach from the west tonight with
scattered showers and isolated thunderstorms.

MVFR conditions prevail early this morning for KGFL/KALB/KPSF
and KPOU with plenty of low-level moisture trapped under an
inversion well north and west of the occluded cyclone near Long
Island. CIGS are generally in the 1.0-2.5 KFT AGL range with
some reductions to IFR levels in terms of cigs possible are at
KPSF. KPOU and KGFL may also have a brief period of IFR after
00Z/THU. Some patchy MVFR mist is also possible at
KGFL/KPOU/KPSF prior to 12Z/THU.

The trend will be for the cigs to slowly rise back to high MVFR
levels in the late morning into the early pm with some drier air
on the northwest side of the cyclone. Some patchy fog is
possible prior to 13Z, but mainly in the MVFR range. A brief
period of clearing is possible in the late afternoon into the
early evening before the next front. However, a cold front will
be approaching from the west with a chance of showers once
again. Cigs will fall back into the MVFR range especially
between 00Z-03Z/FRI.

The winds will be light and variable at 4 kts or less and or
calm this morning. They will increase from the south to
southeast at 5-10 kt late this morning into the afternoon, and
lighten from the S/SE at 3 to 7 kts tonight.

Outlook...

Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Friday Night: Low Operational Impact. Slight Chance of SHRA.
Saturday: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday Night: Low Operational Impact. Slight Chance of SHRA.
Sunday: Moderate Operational Impact. Chance of SHRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.

&&

.FIRE WEATHER...
Cloudy and damp weather will continue into tonight. However, it
should dry out on Thursday with partial sunshine by afternoon.
RH values will fall to 50 to 60 percent on Thursday afternoon
with south winds of 5 to 10 mph. After some passing showers on
Thursday night, dry weather will return again during the day on
Friday. RH values will fall to 45 to 55 percent on Friday
afternoon with west to southwest winds of 5 to 10 mph.

&&

.HYDROLOGY...
As a coastal low finally departs, any lingering drizzle will
end this evening. After dry weather on Thursday, some passing
light rain showers are possible for Thursday night into Friday
morning. QPF amounts will be fairly light with this system,
mainly under a quarter of an inch. Another period of dry
weather is expected for Friday afternoon into Friday night,
before another frontal system moves across the area on Saturday.
QPF amounts will be variable with this front due to the
convective nature of the precipitation. More showers and
possible thunderstorms are possible again Monday into Monday
night with yet another frontal boundary as well.

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



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