Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 161048
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
648 AM EDT Wed Oct 16 2019

.SYNOPSIS...
Clouds will thicken and lower this morning ahead of a low
pressure system and a warm front. A complex storm system will
bring a widespread soaking heavy rainfall into the region late
this afternoon into Thursday along with brisk and cool
conditions. Fair and dry weather with seasonable temperatures
will return Friday into the upcoming weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 648 AM EDT...The fair and dry weather will come to an end
today, as a potent storm system will impact the forecast area
with heavy rainfall and windy conditions late this afternoon
into Thursday. Albany has not had measurable rain since October
7th (8 days).

A digging mid and upper level trough is approaching the
Northeast with southwesterly flow aloft. High pressure is
slowly drifting east/northeast of the Gulf of Maine this
morning. Mid and high clouds are approaching central and
eastern NY ahead of a warm front associated with a strong
northern stream short-wave. A southern stream disturbance is
moving along the Southeast, and will head northeast late this
morning. Some patchy stratus in the Upper Hudson River Valley
will diminish. Clouds associated with the storm system will
thicken and lower from the south and west late this morning into
the afternoon. Temps may warm nicely after a cold start into
the mid 50s to lower 60s. Southeasterly winds will increase at
10 to 20 mph with some gusts 30 to 40 mph west of the southern
Greens and northern Berkshires in the afternoon.

The low to mid level warm advection strengthens ahead the warm
front that merges with the cold front and acts like an occluded
front between the primary wave and the evolving secondary wave
near the Chesapeake Bay Region by this afternoon. The 850 hPa low-
level jet will focus Gulf and some Atlantic moisture for
periods of rain to overspread the region from the
south/southwest to the north/northeast between 2-6 pm. The rain
early this evening will start to come down heavy due to
favorable jet dynamics and strong isentropic lift. Temps will
likely lower due to wet bulb effects. Rapid sfc cyclogenesis is
expected to occur early this evening with the secondary wave.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
Tonight...Two pieces of short-wave energy merge for an intense
secondary coastal low to form near southern NY and southwest New
England. Deep water vapor transport will allow for PWAT
anomalies of +1 to +2 STDEVs above normal from the subtropics to
advect into the region with strong +V anomalies /southerlies/ of
+2 to +3 STDEVs above normal with -U anomalies /easterlies/
possibly getting to +3 to +5 STDEVs above normal by 06Z/THU
according to latest 00Z GEFS. The strong moisture advection will
be tied to an exploding cyclone that potentially deepens and
intensifies to a sub 980 hPa cyclone overnight. Rainfall rates
could exceed a half an inch an hour with 1-3" occurring in the
night time period. Some rumbles of thunder may be possible
especially south of the I-90 corridor due to moist symmetric
instability. The east to southeast low-level winds will enhance
the rainfall off the eastern Catskills, eastern Adirondacks,
and the western New England higher terrain. We leaned close to
the latest ECMWF and WPC QPF. Some poor drainage flooding of low
lying areas due to clogged drains from leaves, twigs, trash and
other debris will be possible. An isolated flash flood may also
occur, as the latest WPC Day 1 graphic has a Marginal Risk over
the entire area. See our hydro discussion for more details if
the potential for widespread flooding looks imminent, then a
Flood Watch may be needed later today.

Another issue late tonight will be the strength of the low and
mid level FGEN. The dynamical cooling as the secondary wave
moves across central and eastern New England may transition some
of the rain to wet snow over the higher peaks of the southern
Dacks, and southern Greens. The low-level winds will swing
around to the north to northwest and be gusty at 10-20 mph with
some gusts in the 35-45 mph range. Lows in the dank air mass
will be in the upper 30s to lower 40s over the mtns, and 40s in
the valleys.

Thursday...Periods of rain continue during the morning into the
early afternoon, as the cold conveyor belt kicks in to the power
system. The sfc wave begins to fill quickly and goes from
cyclogenesis to cyclolysis. The mid and upper level deformation
zone will help enhance the rain for additional quarter to one
inch amounts, which will bring storm totals close to 2 to 4
inches with some locally higher amounts.

Gusty north to northwest winds are expected Thursday morning
into the afternoon, and we will be monitoring if wind advisories
are needed especially from the Hudson River Valley eastward into
western New England. Strong north to northwest winds of 15 to 25
mph with gusts 35 to 50 mph may be possible, especially over the
higher terrain. The pcpn will taper showers by the afternoon,
and snow levels will continue to lower with some light snow
accums over the southern Greens and southern Adirondacks of a
coating to an inch or so. Highs will be in the lower to mid 50s
in the valleys, and upper 30s to mid/upper 40s over the hills
and mtns.

Thursday night...Blustery and cool conditions continue during
the evening with scattered rain and snow showers continuing from
the Capital Region and Berkshires north and west. Again, any
light snow accums will be at elevations greater than 2000 ft.
Coatings to an inch or two at the highest peaks of the eastern
Catskills, southern Adirondacks and southern Green Mountains are
possible. Lows will be in the mid 30s to mid 40s.

Friday...The showery pcpn will end in the morning, as the mid
and upper level low moves northeast in the Canadian Maritimes.
High pressure will be building in from the lower Great Lakes
Region and OH Valley. The skies will become partly sunny, and
the winds will diminish. Temps will be seasonable with 50s in
the valleys, and 40s over the higher terrain.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The period starts out Friday night with a ridge of high pressure both
 at the surface and aloft building eastward into the region.
This will result in mainly clear skies and winds becoming light,
setting the stage for a seasonably cool night. After a cool
start to the day, temperatures will respond nicely with abundant
sunshine as the ridge moves directly over the area.

The surface ridge is expected to shift eastward off the coast Saturday
night into Sunday, allowing for a light southerly flow to
develop. This will result in temperatures warming to above
normal levels Sunday afternoon. Ridging aloft looks to become
reestablished Sunday night into early Monday, so dry conditions
should persist.

Chances for showers will gradually increase on Monday, as a warm front
approaches from the south. With the upper level flow pattern
forecast to amplify, will only mention slight to low chance pops
during the afternoon. It will remain warm with increasing low
level southerly flow. Ridging aloft should persist along or just
off the east coast.

Model guidance has come into better agreement regarding a strong
cold front and deep upper level trough moving across the region
on Tuesday. Low level Southerly flow and moisture flux are
forecast to be anomalously high. Combined with large scale
ascent, this should result in a widespread soaking rainfall.
There are some minor timing differences, but there is enough
confidence to mention likely pops across the entire area.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
A developing Nor`easter will bring a widespread soaking rainfall to
the region this afternoon into Thursday although some
brief/occasional MVFR cigs due to patchy low stratus may occur
at KPOU/KGFL for a few hours this morning. Otherwise, VFR
conditions will prevail with a gradual increase in mid level
clouds prior to the rain developing.

Rain will quickly begin from southwest to northeast between 20Z and
22Z at the terminals. Conditions will rapidly deteriorate to
MVFR, then IFR within a few hours of rainfall onset as precip
becomes moderate/heavy. IFR conditions expected to prevail much
of tonight with moderate/heavy rain continuing.

Low level winds shear will develop at all sites by early this evening,
as a SE low-level jet around 40-45 kt moves overhead. The LLWS
will dissipate once winds abruptly shift to the northwest after
midnight.

Surface winds will initially be light and variable, becoming
southeast around 8-13 kt by late this morning with some occasional
gusts near 20 kt especially at KALB. Then winds will shift to
the northwest after midnight as the storm intensifies, with
speeds increasing to 17-22 kt with gusts around 30-35 kt.

Outlook...

Thursday Night: Low Operational Impact. Breezy Slight Chance of
SHRA.
Friday: Low Operational Impact. Breezy NO SIG WX.
Friday Night to Sunday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
Clouds will thicken and lower this morning ahead of a low
pressure system and a warm front. A complex storm system will
bring a widespread soaking heavy rainfall into the region late
this afternoon into Thursday along with brisk and cool
conditions. Fair and dry weather will return Friday into the
upcoming weekend.

Rainy, brisk and cool conditions are expected this afternoon
into Thursday. Strong southeast winds gusting to 25 to 40 mph
are expected this afternoon and evening. The winds will shift to
the northwest Thursday morning at 15 to 25 mph with some gusts
35 to 45 mph. The winds will gradually subside Thursday night.

&&

.HYDROLOGY...
A widespread soaking rainfall is expected this afternoon into
Thursday. Some increased flows on the main stem rivers are
likely. Some points are expected to reach action or alert stage
but not reach flood stage based on the latest NERFC forecasts.

Two to four inches of rainfall are possible in some locations
with some isolated locally higher amounts. Within bank rises are
possible on the main stem rivers. Some ponding of water on
roadways and poor drainage flooding of low lying areas is
possible due to the moderate to potentially heavy rainfall in a
12 to 24 hour time frame. The latest MMEFs guidance indicates no
problems in the ALY HSA. If confidence increases for the
potential for widespread flooding, then a Flood Watch may be
needed later.

A period of dry weather will return Friday into the weekend
which should allow flows to slow and lower.

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...JPV
AVIATION...JPV
FIRE WEATHER...Wasula
HYDROLOGY...NAS/Wasula


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