710 
FXUS61 KALY 151048
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
648 AM EDT Sun Aug 15 2021

.SYNOPSIS...
High pressure building into the region has allowed for 
overnight lows to drop into the 40s to 50s across the region. After 
a cool start Sunday, high temperatures will rebound into the 70s 
with mainly clear skies. Sunday night looks cool with another 
pleasant day expected Monday. However, warmer and more humid weather 
looks to return Tuesday through the end of the week. There will 
also be a chance for showers and thunderstorms each day, mainly 
during the afternoon and evening.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
.Update...As of 6:40 AM EDT, skies remain mostly clear outside
of a few scattered high clouds. Some patchy fog has developed
over the past few hours, but any fog/mist should mix out rather
quickly this morning as continued mostly clear skies will allow
for the boundary layer to heat up rather quickly after a fall-
like start to the morning. High pressure over Lake Erie and Lake
Ontario has allowed for efficient radiational cooling over
western areas this morning, so made some adjustments to current
temperatures and dew points to reflect these trends. Otherwise,
just made some minor adjustments to sky cover and winds to 
reflect current obs. Previous forecast for a mainly dry and 
clear late-summer day with highs in the 60s (high elevations) to
upper 70s/low 80s (valleys) remains on track...


Skies remain mostly clear as high pressure continues to build
into the region from the west. As of 3:30 AM EDT, just a few
high clouds showing up on satellite imagery. Also beginning to
see some patchy fog develop in some of the sheltered
valleys. There is quite the range in temperatures across the
region this morning; temperatures range from 45 at Old Forge to
63 at Voorheesville per NY S Mesonet obs. Areas that have
decoupled have radiated quite efficiently with clear skies, but
winds have not gone completely calm for eastern further away 
from the surface high. Reduced overnight lows with the previous
update, so just made some relatively minor adjustments to 
capture current trends this morning. 

Sunday looks to be a beautiful day. The 1025 mb high centered
near the Great Lakes should move eastward towards our region
through the day today. Combination of surface high pressure, 
height rises, and confluent flow aloft will lead to large-scale 
subsidence that should keep skies mainly clear through much of 
the day. Advection of cooler and drier air into the region 
should continue through the day today, which will keep daytime 
highs in the upper 60s/low 70s in the higher elevations and mid-
upper 70s elsewhere.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
Sunday night looks to be a repeat of tonight. Conditions may be
even more favorable for radiational cooling with the surface
high expected to be located over upstate NY, so generally went
with lows a degree or two colder than those tonight. BUFKIT 
model soundings suggest the development of a nocturnal 
inversion with calm winds and mainly clear skies, so expecting 
temperatures to drop rather quickly once again after sunset. 
Therefore, have gone a few to several degrees below NBM guidance
for nighttime lows, especially for northern areas closest to 
the center of the high. Only potential fly in the ointment that 
could prevent temperatures from really bottoming out is the 
arrival of some more high clouds towards morning, but current 
thinking is that clouds will not be thick enough or low enough 
to prevent favorable radiational cooling conditions. 

Monday, we switch to a warm advection regime as a weak warm
front lifts northward across the region sometime during the
morning. This happens as the surface high begins to slide to our
east over New England and an upper-level ridge begins to build
over our region. It will be a touch warmer and more humid than
Sunday, but much warmer/more humid air should remain to our
south, which will make for yet another pleasant day with highs
in the 70s to around 80.

Monday night will not be as cool as the previous few nights, as
advection of warmer and more moist air into our region will
continue. There will also be more cloud cover, which will 
further prevent temperatures from falling as much as they did 
the previous few nights. The upper-level ridge will begin to
move eastward and a broad upper-level trough will approach from
the west towards daybreak Tuesday, so there could be an isolated
shower around late Monday night/early Tuesday morning. However,
only included slight chance PoPs for western areas as best
forcing looks to remain to our west until Tuesday.

Tuesday...Upper-level ridge moves east and we get into a S?SW 
flow regime with upper-level troughing just to our west. An 
upper-level shortwave moving through the mean trough may enhance
forcing for ascent Tuesday afternoon. With Dew points 
increasing into the mid-upper 60s and PWAT values rising to 1.8 -
2.0" there will be an increased chance for some showers and 
possibly a rumble of thunder in the afternoon. With model 
forecast soundings showing only a few hundred joules of CAPE, 
only included a slight chance for thunder. While it will be more
humid, abundant cloud cover will likely keep high temperatures 
in the 70s and low 80s. Coverage of showers diminishes Tuesday
night, but it will remain muggy with lows only in the 60s.

Wednesday will be very similar to Tuesday with an upper-level
ridge to the east, troughing to the west, and S/SW flow that
will continue advection of warm, moist air towards our region.
We will also be watching the remnants of Fred, which may be
picked up by the trough to our west and track towards our region
Wednesday. There is some uncertainty in the details of how 
Fred's remnants interact with the upper-level trough, but models
are in fairly good agreement that Fred's remnants will be
absorbed by the trough and track northeastward towards our
region Wednesday, which could lead to more widespread coverage
of showers and thunderstorms during the evening compared to 
Tuesday. Daytime highs will once again be 70s to around 80s due
to abundant cloud cover and showers, but it will be rather 
humid with dewpoints in the 60s to low 70s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
A rather unsettled pattern expected in the long term as we watch for 
potential remnant impacts of TS Fred to move through the region. 
Otherwise, warm and humid with the threat of mainly afternoon and 
evening convection.

Latest 00Z global model consensus suggests our evolving southwest 
flow regime will advect in warmer and more moist environment 
Wednesday night into Thursday.  This too will be along and ahead of 
remnants of TS Fred expected to arrive sometime late Wednesday 
night into Thursday morning.  Rainfall associated with this system 
embedded within anomalous high PWATs could result in a period of 
moderate to heavy rainfall.  

In the wake of this system, models diverge a bit as we either watch 
the evolution of an upper low to develop across the northeast 
corridor as suggested by the ECMWF or a building ridge as suggested 
by the GGEM and GFS.  Either way, seems we will remain within a 
cyclonic flow regime to keep the chance of convection coinciding 
with daytime heating as H850 temperatures slowly moderate into the 
mid and upper teens celsius with breaks of sunshine expected.  

High temperatures through the period will moderate a few degrees 
each day with mostly 80s expected by next Saturday and overnight 
lows generally into the 60s.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Patchy ground fog across the region per early morning satellite 
imagery, however, not impacting TAF locations.  As sunrise has 
occurred, fog should quickly dissipate as VFR conditions will 
prevail.  Occasional CI/CS will stream across the mid-August sky 
with winds generally less than 10kts from the northwest or north. 

Some of these higher clouds will thicken toward sunset but should 
remain VFR at all TAF sites. Winds will be light and variable. 

Outlook...

Monday Night: Low Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. Chance of SHRA...TSRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thursday: Moderate Operational Impact. Chance of SHRA...TSRA.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Chance of SHRA.

&&

.FIRE WEATHER...
Fair weather with cooler and less humid conditions as high
pressure builds in and dominates into early next week. Chances
for showers and thunderstorms will return for Tuesday through
the end of the week each day, mainly during the afternoon and
evening.

RH values are currently in the 90-100% range for most of the
region this morning, but will decrease to 40-50% this afternoon.
RH values recover to at least 80-90% overnight tonight and will
drop to 40-50% once again Monday.

&&

.HYDROLOGY...
Fair weather with cooler and less humid conditions as high
pressure builds in and dominates into early next week. Chances
for showers and thunderstorms will return for Tuesday through
the end of the week each day, mainly during the afternoon and
evening. 

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...Main
NEAR TERM...Main
SHORT TERM...Main
LONG TERM...BGM
AVIATION...BGM
FIRE WEATHER...IAA/Main
HYDROLOGY...IAA/Main