Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 291210
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
810 AM EDT Sat Apr 29 2017

.SYNOPSIS...
A cold front will move across the region this morning with mainly
isolated showers for the majority of the area, as clearing skies,
breezy and mild conditions are expected in the afternoon. High
pressure builds in from southeastern Canada tonight into Sunday with
cooler conditions.  A warm front will slowly lift northward late
Sunday into Monday with an increasing threat of showers and isolated
thunderstorms.  A cold front will bring widespread showers and a
chance of thunderstorms late Monday afternoon into Tuesday
morning

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 810 AM EDT...A cold front continues move across the
eastern Great Lakes into central and northern NY this morning.
Dewpoint at BUF about 10 degrees F lower than ALB. Satellite
shows skies are mostly cloudy. Radar shows a band of showers
moving into the western Adirondacks so increased POPs from there
into Lake George Saratoga Region this morning. Elsewhere,
nothing on radar so lowered POPs and took out mention of
thunderstorms.

Previous...
MCS that completely missed most of southern NY and the southern
tier of the ALY fcst area. The mesoscale models had a tough
time with the northern extent of the MCS/cluster of convection
that grazed the NYC area. Most of the ALY forecast just has some
widely scattered showers or sprinkles. We have reduced the POPS
to slight chc for isolated showers except the upslope areas of
the southern Greens and srn Dacks. Some weak elevated
instability is south and west of the Capital Region, so will
leave an isolated threat for thunderstorms. Overall, believe
most of the day will be dry now that the MCS robbed most of the
moisture and stayed south. The 06Z and latest 3-km HRRR finally
caught on to the drier scenario.

The short-range guidance has the isolated shower activity ending
prior to noontime, as the cold front pushes southward. The
NAM/GFS have a few showers/isolated thunderstorms trying to
sneak into the eastern Catskills on north side of the boundary.
We kept a slight chc of showers or thunderstorm in the
afternoon. This activity should fizzle with the strong
subsidence in the wake of the cold front.

The winds will increase from the west in the afternoon at 10 to
20 mph with some gusts around 25 to 30 mph in the Capital
Region/Mohawk Valley. The skies should become at least partly
sunny with mild temps once again due to good mixing and
downsloping off the higher terrain west of the Hudson Valley.
Highs will be in the mid and upper 70s over the valley areas and
in NW CT with a few lower 80s in the mid-Hudson Valley with 60s
to lower 70s over the hills and mtns.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Saturday night...The front moves further south to the OH Valley
and Mid Atlantic Region, as high pressure builds in south of
James Bay. Cold Advection will occur in the wake of the front
with H850 temps falling to 0C to +5C from the Capital Region
north and west, and +5C to +10C south and east.  Most of the
night period will be dry and cool with lows in the mid 30s to
lower 40s from the Mohawk Valley/Lake George Region and southern
VT northward...and mid 40s to lower 50s south of these areas. A
light north to northeast wind will persist at night bringing
down the chilly temps.

Sunday...Weak low-level warm advection begins, as the cold front
starts to drift back northward as a warm front. The NAM and NAM
MOS guidance continue to be a cold outlier solution with max
temps 10 to 15 degrees colder the MAV MOS guidance. We trended
closer a blend of the short-range guidance and the EC MOS which
is about 5 to 7 degrees warmer than the NAM MOS. Sunday looks
like a cloudy and cool day with mid level heights rising as
ridging tries to build in from off the East Coast. Plenty of
low-level moisture will be trapped under an inversion. The sfc
high shifts east over eastern New England. The latest EC and CAN
GGEM has the strongest isentropic lift for some afternoon
showers moving from south to north over the fcst area. We kept
slight and low chc pops over the region. The GFS/NAM has less
pcpn. Clouds and pcpn should keep temps much cooler than the
previous few days with 50s to lower 60s across most of the fcst
area.

Sunday night into Monday...The warm front moves through the
forecast area with a chance of showers or even drizzle late Sunday
night into Monday morning. The low-level east to southeast flow
with the sfc high off the coast may keep low stratus around
into Monday morning. Upstream...low pressure intensifies and
moves into the upper MS River Valley and Upper Midwest Sunday
night. The cold front will slowly track into the eastern Great
Lakes Region and Ohio Valley Monday afternoon. After another
cool night with lows in the 40s to around 50s, expect the highs
on Monday will recover into the 60s to lower 70s. Again,
abundant cloud cover may persist into the late morning/early pm.
The chc of showers and thunderstorms increases in the late
afternoon especially west of the Hudson River Valley. A strong
low-level southerly jet at H850 sets up over the region at
40-50+ kts which will help advect in a humid air mass with sfc
dewpts rising into the 50s to around 60F

Monday night...The best synoptic lift and convergence occurs
head of the front during this time frame. Pops were kept in the
likely and categorical values. PWATS surge above normal. The
strong convergence with the front and decent upper level
dynamics should keep the threat of thunderstorms going until
midnight or shortly thereafter. The Day 3 Marginal risk from
SPC barely touches Herkimer CTY. We will just mention a chance
of thunderstorms in the HWO.  A decent burst of rainfall is
likely on the order of a quarter to half an inch with the front.
Lows will be in the upper 40s to upper 50s across the region.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The long term period will be dominated by general troughiness,
plenty of clouds and rain chances. At upper levels, we begin with a
strong closed off upper low lifting into Quebec on Tuesday. Trailing
upper level energy across the region will allow for continued shower
chances through Wednesday evening. Weak ridging builds into the
forecast area for Wednesday night as our next weather maker forms in
the southern Plains. This system helps deepen and elongate the upper
level trough over the central CONUS on Thursday and then makes its
way towards the northeastern US.

There is a lack of consensus among models for the Thurs-Sat time
frame. The GFS closes off the upper low but keeps it further south
across the southeastern US, whereas the ECMWF closes off the upper
low over the Ohio Valley but also deepens the upper trough across
the Northeastern US. Even though there are substantial differences
in the model solutions, both bring additional rainfall chances to
the forecast area Thursday through Saturday with the best chance for
steady rainfall Thursday night. Given the model differences have
remained close to the superblend, especially in terms of temps and
pops for the end of the work week into next weekend.

With unsettled weather and plenty of cloudiness expected throughout
the period, temperatures will average near or slightly below normal.
The only exception is Tuesday where high temperatures could reach
the upper 60s. Otherwise, highs will be in the 50s and low 60s.
Overnight lows will generally be in the 30s (high terrain) and 40s
each night.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
The overnight shower activity stayed south of the region,
keeping the TAF sites dry. There are still a few light scattered
showers over the western Adirondacks that are forecast to dry up
before reaching TAF sites. Expect VFR conditions through the
forecast period as a weak surface ridge builds into the region.

Winds will be mainly out of the southwest at 5 knots or less
this morning but then shift back to the west this afternoon.
Gusty west winds up to 20-25 knots will also be possible this
afternoon.

Outlook...

Sunday Night: Low Operational Impact. Slight Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday Night: High Operational Impact. Likely SHRA...TSRA.
Tuesday: Moderate Operational Impact. Breezy Chance of RA.
Tuesday Night: Low Operational Impact. Slight Chance of RA.
Wednesday: Moderate Operational Impact. Breezy Chance of RA.
Wednesday Night:  Slight Chance of RA.
Thursday: Moderate Operational Impact. Chance of RA.

&&

.FIRE WEATHER...
A cold front will move across the region today with isolated
showers and thunderstorms, as clearing skies, breezy and mild
conditions are expected in the afternoon. High pressure builds
in from southeastern Canada tonight into Sunday with cooler
conditions. A warm front will slowly lift northward late Sunday
into Monday with an increasing threat of showers and isolated
thunderstorms.

Rainfall will be fairly light and scattered today. Behind this
front, clearing will occur by this afternoon, with RH values
falling to 35 to 50 percent with west winds increasing to 10 to
20 mph with a few gusts 25 to 30 mph.

RH values will recover 65 to 75 percent tonight with north to
northeast winds of 5 to 10 mph. Expect the RH values to lower to
50 to 60 percent with scattered light showers on Sunday as the
winds will shift to east to the southeast at 5 to 10 mph.

&&

.HYDROLOGY...
Rainfall amounts will be under a tenth of an inch with the cold
front today with no impact on the waterways in the ALY Hydro
Service Area.

After a brief period of dry weather this afternoon into
tonight, the front will return as a warm front for Sunday into
Sunday night. Rainfall amounts will be fairly light once again,
with a few hundredths to a tenth of an inch or so.

A stronger cold front will cross through the region late Monday
afternoon into Monday night. This front may allow for some
locally higher rainfall totals due to more widespread showers
and a chance of thunderstorms due to a more humid air mass.
No problems are anticipated on the main stem rivers (as shown
in the MMEFS). Rainfall amounts will range from a quarter to
half inch with some locally higher amounts in thunderstorms.
Ponding of water on roadways or low lying areas and poor
drainage within urban areas will be 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...Wasula
NEAR TERM...SND/Wasula
SHORT TERM...Wasula
LONG TERM...JVM
AVIATION...SND/JVM
FIRE WEATHER...Wasula
HYDROLOGY...Wasula


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