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000
FXUS61 KALY 120540
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
140 AM EDT Wed Aug 12 2020

.SYNOPSIS...
A cold front will stall near New York City Wednesday through
Friday, resulting in some possible showers and thunderstorms
each day across the mid-Hudson Valley into northwest
Connecticut. Elsewhere, it will be mainly dry. Temperatures and
humidity levels will be slightly lower for the rest of the week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 1259 AM EDT...Still seeing renewed convection along old
outflow boundary across parts of Dutchess, southern Berkshire
and Litchfield Counties. Downpours and some lightning will
continue over the next few hours before moving out of the area.
Additional rainfall amounts could still reach 0.50 to 1.00
inches in the most persistent storms. Still enough MLCAPE around
500-1000 J/Kg to support convection overnight, although DCAPE
has diminished due to stabilization of the boundary layer.
Increased pops across the southern part of the area for the
convection moving through.

In the wake of the showers and thunderstorms, clouds will
partially break with the potential for some patchy fog in some
valley locations. Lows will drop into the 60s to lower 70s, with
muggy conditions persisting.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
Wednesday and Thursday will feature mostly dry and slightly
cooler and less humid weather across the region. The cold front
which moved across the region on Tuesday night will continue to
push farther south and east and eventually stall near New York
City. Along this front, additional showers and thunderstorms
will be possible each day. Most of the activity should stay
south of the region during this time period but an isolated
shower or thunderstorm cannot be ruled out across the mid-
Hudson Valley into northwestern Connecticut, as they will be the
closest to the front. Pops were lowered significantly from the
previous forecast and in collaboration with surrounding offices.

Farther north, a large area of high pressure will slowly build
over the region and bring a cooler, less humid and drier air
mass. Dew points will drop into the 50s to lower 60s, making it
feel a bit more comfortable.

Highs both days will range from the upper 70s in the higher
terrain to the low to mid-80s elsewhere with lows in the 50s to
lower 60s.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The long-term forecast period looks to feature a downtrend in
temperatures from warmer than normal levels at the period`s onset to
closer to normal or even slightly cooler than normal values late in
the period. As far as precipitation, the period is expected to be
mostly dry particularly through the first half of the extended
before chances increase late Sunday through Tuesday.

This is all part of a potential large-scale pattern change where the
heat ridge, which has been so vast and intense across much of the
country for much of this season, focuses more on the western U.S.
(with the closed 594+ dam heat dome parked over the Southwest U.S.).
This will allow the potential for weakness (in the form of upper
troughiness) in the H500 pattern to develop over the eastern U.S. In
fact, global ensembles all indicate an upper trough to track from
western Canada into central Canada and dig over the central United
States. By Monday, forecast models are showing the mean trough axis
to be established from the Hudson Bay into the Great Lakes and
Appalachia.

At the surface, a cold front will approach the FA from the west late
Sunday night into Monday with showers and thunderstorms along and
ahead of it. This coupled with mid to upper impulses associated with
the aforementioned upper trough will support the potential for
showers and thunderstorms Monday across eastern New York and western
New England. Broad cyclonic flow aloft associated with mid to upper
impulses still hanging over the region could support in another bout
of some diurnal shower and thunderstorm development across the FA on
Tuesday.

Friday through Sunday, the deterministic models (particularly the
ECMWF and Canadian-NH) shows surface high pressure over the area
providing for plenty of subsidence and thus dry/tranquil weather.

Temperatures as touched on earlier, will undergo a downtrend through
the extended. Daytime high temperatures on Friday are expected to
reach the mid 80s in the valleys decreasing to the upper 70s to near
80 by Tuesday (cooler higher elevations). Nighttime lows are
expected to be mainly in the 60s through the extended (50s higher
elevations).

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
A line of showers and storms has moved through the region and is
currently exiting the southeastern zones of the forecast area as
of 0530Z. A few showers may linger at KPOU for the next hour or
two but all other TAF sites should remain dry. Some clearing is
expected behind the line, which should promote some BR/FG
development, especially since all TAF sites did receive rain.
Will have to monitor as skies clear and winds lighten further
over the next couple of hours.

After daybreak, flying conditions will return to VFR for the
remainder of the day.

Winds will be light and variable overnight, becoming mainly
westerly around 5-10 kts during the day.


Outlook...

Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
Isolated showers and thunderstorms are expected into this
evening before a line of showers and thunderstorms push from
west to east across the region tonight. This will result in RH
values increasing to between 90 to 100 percent.

A drier and slightly cooler and less humid air mass slowly
builds across the region on Wednesday and Thursday. Any
shower/thunderstorm chances will be across the mid-Hudson Valley
into northwestern Connecticut. RH values will drop to around
40-55 percent during the day and rebound to between 85 and 100
percent at night.

Winds will decrease to around 5 mph tonight. Winds both
Wednesday and Thursday will be between 5-10 mph.

&&

.HYDROLOGY...
No widespread hydrological problems expected in the ALY Hydro
Service Area over the next several days.

A line of showers and thunderstorms are expected to move from
west to east across the region tonight. On Wednesday and
Thursday, only isolated shower or thunderstorm activity is
expected across the mid- Hudson Valley into northwestern
Connecticut with dry weather elsewhere. Locally heavy rainfall
associated with thunderstorms may result in ponding of water or
poor drainage flooding of low lying and urban areas. No river
flooding is forecast at this time.

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/Rathbun
NEAR TERM...SND/JPV/Rathbun
SHORT TERM...Rathbun
LONG TERM...Evbuoma
AVIATION...JLV
FIRE WEATHER...Rathbun
HYDROLOGY...Rathbun