Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 281053
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
653 AM EDT Fri Apr 28 2017

.SYNOPSIS...
A weak cold front will move east of the region this morning with
isolated to scattered showers ending, as high pressure will
build in from the Ohio Valley and Pennsylvania with increasing
sunshine and above normal temperatures. Another cold front will
impact the region late tonight into Saturday with scattered
showers and isolated thunderstorms. The boundary will lift
northward as a warm front late Sunday into Sunday night with
more unsettled weather into early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 621 AM EDT...A cold front continues to make steady
progress eastward across eastern NY this morning. The shower
coverage has been sparse with the majority of the showers from
the Capital Region north and west closer to the right jet
entrance region of an H250 jet streak. This update is to account
for an area of isolated showers ahead of the front moving
across the Schoharie Valley and the central-eastern Mohawk
Valley. These showers should clear the forecast area after 8 am.
Some adjustments were made to temp trends, but overall the
forecast is in decent shape with cloudy conditions into the late
morning before clearing skies.

As the cold front pushes eastward, drier air at the sfc and
aloft will move into the region. The strong subsidence in the
wake of the front, and with a sfc anticyclone building in from
the Ohio Valley will yield partly to mostly sunny conditions
with west winds of 10 to 15 mph. H850 temps will range from +7C
to +11C with the weak cold advection in the wake of the front.
Good mixing coupled with the afternoon sunshine and some
downsloping off the mountains to west of the Hudson River Valley
will allow for highs in the upper 70s to lower 80s in the
Hudson River Valley and CT River Valley, lower to mid 70s over
the hills and other valley areas, and mid 60s to around 70F over
the mtns.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
Tonight...Tranquil conditions begin the evening, as high
pressure moves overhead, but then shifts east northeast across
northern New England. Mid and upper level southwesterly flow
sets up over the region, as another cold front approaches from
southeast Canada, the eastern Great Lakes Region, and Midwest. A
short-wave in the southwest flow and a prefrontal trough help
focus some scattered showers after midnight...generally between
06Z-12Z/SAT based on the NAM/GFS/ECMWF/CAN GGEM and many of the
Global Ensemble members. The synoptic forcing looks weak, but
there is enough isentropic lift for the scattered showers. Lows
will generally be in the 50s with some mid and upper 40s over
the southern Adirondacks, and southern Greens.

Saturday...The forecast is a little muddled here in the
guidance, as the question is how quickly the cold front sweeps
across the forecast area. The boundary should be making steady
progress across the northern half of the forecast area, and then
shift south and east of the I-90 corridor during the afternoon.
There is a slight chc of thunderstorms with some surface based
instability on the GFS/NAM. The GFS is too high with SBCAPES of
500-1200+ J/kg south and east of the Capital Region, as it has
sfc dewpts well in the mid 60s. We are expecting mid 50s to
around 60F dewpts in those areas. There is definitely a threat
of thunderstorms with at least low amounts of CAPE and
appreciable low-level moisture. The NAM continues to whip up
some MCS like structures along the front Saturday morning into
the afternoon. This looks like some convective feedback, but
overall we will keep a chance of showers in the forecast with
isolated thunderstorms from the Capital Region south. The post
frontal winds should increase from the west to northwest at 10
to 20 mph. Highs will be still be above normal mid 70s to around
80F from the Greater Capital south and east into the mid Hudson
Valley and NW CT...with 60s to lowers 70s north and west, with
some 50s over the southern Adirondacks.

Saturday night...There is stronger cold advection with this
front compared to the previous one. It is a much drier low-level
air mass too in terms of the sfc dewpts falling into the 30s and
40s. The question will be how far south the cold front stalls
and becomes stationary. It looks it will make it as far south as
the Ohio Valley and the PA/MD border. High pressure attempts to
build in from James Bay.The majority of Saturday night should
be dry, but some light over-running sprinkles or showers may
impact locations well south and west of the Capital Region. Lows
will be on the chilly side with mid 30s to lower 40s north of
the Mohawk Valley/Capital Region, and mid to upper 40s mainly
from these areas south and east.

Sunday-Sunday night...A impressive cyclone forms over the
central Plains and MO with its associated mid and upper level
trough becoming negatively tilted. The systems warm front will
begin to move northward towards the region on Sunday. Sfc high
pressure builds in from southwest Quebec and then shifts
offshore with a mid level ridge over the western Atlantic
trying to build in. The question will be how fast the warm front
lifts northward back across the fcst area. Increasing clouds,
and strengthening isentropic lift along the 295K sfc is
expected late Sun pm into Sunday night for a chance of showers
and perhaps a rumble of thunder. Most locations may stay dry the
better past of Sunday until the late pm. Highs are tricky on
Sunday comparing the NAM MOS vs the GFS MOS with 10-15 degree
differences with the NAM MOS much cooler. We hedged closer to
the GFS MOS guidance with highs in the mid 50s to mid 60s. Lows
will generally be in the 40s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The upper level pattern remains progressive but amplified throughout
the extended period. On Monday, a strong and closed off upper low
will lift through the Great Lakes region. Energy from this low will
traverse around the upper level trough through our area Tuesday.
Weak ridging builds into the forecast area on Wednesday as our next
weather maker dives out of the Pac NW into 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-Fri time frame as the GFS closes off the upper low and brings
a very strong system up the eastern seaboard, whereas the ECMWF
subdues the closed upper low along the Gulf coastline. Given these
differences have remained close to the superblend, especially in
terms of temps and pops for the end of the work week into next
weekend.

At the surface, we will begin in the warm sector on Monday with
perhaps a few scattered showers and thunderstorms. Rain will become
more widespread with a chance for thunderstorms Monday night as a
cold front passes through the region. Some of these storms have the
potential to become strong but the timing isn`t optimal in terms of
instability. Shower activity remains in the forecast for Tuesday as
additional waves of upper level energy pass through the Capital
Region. Wednesday looks to be mostly dry south of the Capital
District with shower activity to the north. A coastal low brings
additional rain chances Thursday, potentially lasting into the
weekend.

With unsettled weather and plenty of cloudiness expected through the
period, temperatures will average near or slightly below normal. The
only exception is Monday where high temperatures could reach the low
to mid 70s. Otherwise, highs will be 50s and low 60s. Overnight lows
will generally be in the 30s (high terrain) and 40s each night.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
The cold front is currently passing through the Greater Capital
District as of 11Z. IFR/MVFR CIGS are affecting all sites ahead
of the front with some fog now settling into KPOU/KPSF. However,
conditions should quickly improve to VFR behind the front as it
passes through the TAF sites early this morning. VFR conditions
will then prevail through the remainder of the TAF period.
There is the potential for some light showers towards daybreak
tomorrow.

Winds will be mainly out of the west at 10 knots or less through
the period.

Outlook...

Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday Night: Moderate Operational Impact. 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.


&&

.FIRE WEATHER...
High pressure builds in this afternoon with dry weather briefly.
Another cold front will impact the region late tonight into
Saturday with scattered showers and isolated thunderstorms. The
boundary will lift northward as a warm front late Sunday into
Sunday night with more unsettled weather into early next week.

The RH values will fall to 30 to 40 percent this afternoon
with west winds of 5 to 15 mph. The RH values will recover to 75
to 100 percent tonight with a chance of showers late, as the
winds will be from the south to southeast at 5 to 10 mph.

With another frontal boundary nearby, some showers or
isolated thunderstorms will be possible on Saturday. This will
allow prevent RH values from not getting as low as Friday, with
readings only as low as 45 to 60 percent on Saturday afternoon.
West to southwest winds will be 10 to 20 mph on Saturday, with
a few higher gusts possible as well.

&&

.HYDROLOGY...
Rainfall amounts were light from the cold front this morning
with generally a few hundredths to a tenth of an inch with
around a quarter of an inch over portions of the southern
Adirondacks. Little impact occurred on the main stem rivers.

Dry weather is expected today, but another frontal boundary
will return the threat for some scattered showers and isolated
thunderstorms between late tonight into Saturday evening.
Rainfall amounts will again be variable with generally a tenth
to a quarter of an inch where the showers/thunderstorms occur,
but basin average amounts shouldn`t be enough to cause any
hydrologic issues.

After a mainly dry day on Sunday, another frontal boundary is
expected to impact the region between Monday and Monday night.
This front may allow for some locally higher rainfall totals due
to more widespread showers and thunderstorms and a more humid
air mass. Although no problems are anticipated on the main stem
rivers (as shown in the MMEFS), high water or poor drainage within
urban or poor drainage 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...Wasula
SHORT TERM...Wasula
LONG TERM...JVM
AVIATION...JVM
FIRE WEATHER...Frugis/Wasula
HYDROLOGY...Frugis/Wasula


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