157
FXUS61 KALY 191030
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
630 AM EDT Thu Sep 19 2024

.SYNOPSIS...
A coastal low will remain off the New England coast today,
keeping our region mainly dry under filtered sunshine with
slightly above normal temperatures. Our coastal low tracks south
and west late tonight into tomorrow as a backdoor cold front
also slowly slides southwestward through Saturday, resulting in
a few isolated to scattered showers. Then, seasonably cooler
and dry weather arrives for Sunday into the first half of next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 620 AM EDT...Cooling cloud tops are clearly evident via
GOES16 IR satellite this morning around our coastal low
positioned off the coast of Nantucket, indicative that our
coastal low continues to deepen/organize. While much of the
night featured mostly clear skies with just some thin cirrus, a
thicker cirrus canopy associated with this coastal low has
spread into areas along and east of the Hudson River. These
clouds combined with some weak sfc winds has mitigated fog
development, especially in comparison to yesterday morning.
These clouds have helped keep overnight lows mild with many
waking up to temperatures in the mid to upper 50s to even around
60. Cooler in the southern/western Adirondacks and western
Mohawk Valley with temperatures in the upper 40s to low 50s
where clouds are thinner.

Previous discussion...The coastal low just south of Nantucket
this morning will slowly progress northeastward and become
positioned just south and east of Cape Cod as it slowly
deepens/becomes better organized. With the low being displaced
well to our south and east, an amplifying ridge centered over
the Corn Belt States and extending into the Great Lakes/Ontario
will actually have more of an influence of our sensible weather
for today. Cirrus clouds extending inland from our coastal low
will still be overhead but increasing subsidence from the nearby
ridge will help scour out some of the cirrus and lead to more
filtered sunshine. The exception will be western New England
where mid- level clouds from our coastal low will be spreading
inland late this afternoon leading to increasing late day
clouds. Despite our coastal low will be deepening today, showers
rotating inland look to remain mainly to over eastern New
England.

The increased insolation combined with still 850hPa isotherms
ranging +13C to +15C will support above normal high temperatures
this afternoon. In fact, the offshore coastal low will also
keep the sfc pressure gradient a bit tight and given the dry
atmospheric column in place, support deep boundary layer mixing
extending up to 850hPa. Thus, expecting a rather warm afternoon
with probabilistic guidance indicating >80% confidence for the
Hudson and Mohawk Valley to exceed 80 degrees. Generally
expecting highs to reach into the low 80s in valley areas with
mid to upper 70s in the hill towns and higher terrain. With dew
points also a bit higher today in the low 60s, it will feel warm
today. Typical high temperatures this time of year are in the
upper 60s to low 70s so we should end up near 10 degrees above
normal.

For tonight, our coastal low continues to gradually deepen south
of Cape Cod with high pressure from Ontario building into the
Northeast. The majority of the low and mid-level clouds
associated with our coastal low once again remain displaced to
our east with high pressure centered to our west maintaining
control. Another mostly clear night expected with partly cloudy
skies in western New England given closer proximity to our
coastal low. Overnight lows again only dropping into the mid to
upper 50s and with dew points in a similar range, patchy valley
fog is once again expected.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Our coastal low continues to spin south and east of Cape Code
on Friday, closing off up to 500hPa, and even slowly
retrogrades south and westward closer to the eastern end of
Long Island. High pressure remains centered in southern Ontario
with a backdoor cold front slowly sliding south and westward
from northern New England into eastern NY. Additional shortwave
impulses rotating counter clockwise around our closed 500hPa low
look to interact with the incoming backdoor front, and provide
additional forcing for ascent as the front tracks into our area.
While overall moisture is low, it appears sufficient enough to
support a few isolated to scattered showers on Friday,
especially from the Hudson River eastward into western New
England. Probabilistic guidance shows a weak signal for
diurnally and terrain driven scattered showers with
probabilities capped at 25 - 40% at best. Any shower that does
develop is likely light in nature producing just a few
hundredths of QPF.

We show slight chance POPs in the Hudson River Valley trending
to chance for southern VT, Berkshire, and Litchfield County.
Otherwise, expecting high temperatures to be slightly cooler
compared to Thursday, with much of area only reaching into the
mid to upper 70s. Coolest in western New England where cloud
coverage will be thicker with highs only in the upper 60s to low
70s. It will also be a bit breezy with northeast winds becoming
sustained around 5-8kts and gusts up to 15kts again strongest
in western New England closer to our coastal low. Skies south
and east of Albany should actually remain mostly sunny as this
area remains displaced from the backdoor front and coastal low
while areas north and especially east of the New York Capital
turn partly to mostly cloudy.

Our backdoor front slows down and lingers overhead into Friday
night keeping skies partly to mostly cloudy. We maintained
slight chance POPs in western New England but overall expecting
a dry night. With increased clouds, temperatures remain mild
with overnight lows only dropping into the mid to upper 50s with
around 60 in the valley. Dew points remain a bit elevated as
well so it will remain feeling mild.

Our front remains overhead into Saturday but slowly slides south
and westward as it washes out. Skies become partly to mostly
cloudy with temperatures trending cooler, only rising into the
low to mid 70s as the cooler air mass behind our backdoor front
spills into the area.The slightly breezy northeast winds will
also help make it feel cooler. We continue to show slight chance
POPs in western New England but with our backdoor front
"kicking" our coastal low southward away from Long Island, we
overall potential for isolated to scattered showers is lower
compared to Friday.

Skies partially clear Saturday night as high pressure centered
in eastern Quebec and its associated drier air mass build
southward. Overnight lows a bit cooler compared to previous
nights dropping into the low to mid 50s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Upper level ridging and surface high pressure continues for Sunday
through Tuesday to start off the work week. Dry conditions are in
store with cooler and seasonably normal temperatures for fall and
mid-September. Latest National Blend of Models 4.2 data (NBM)
probabilistic model guidance has high temperatures in the 60s and
lows in the 40s and 50s.

Beyond Tuesday, ensemble forecast model guidance has uncertainty if
an upper level trough develops over the Great Lakes that could bring
precipitation to eastern NY and western New England for mid week.
Latest probabilistic model guidance shows increasing probability of
precipitation for Tuesday night and Wednesday, where eastern NY and
western New England could receive some accumulating precipitation.
At this forecast period, probabilities of seeing 24 hour rainfall
amounts of at least a trace are between 25 and 45 percent for next
Wednesday. We`ll continue to monitor trends for next week. High
temperatures for Wednesday are forecasted to be upper 60s and low
70s.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Through 12z Friday... Low ceilings at KPOU should diminish between
12z and 13z with low VFR conditions. Then high to mid level clouds
should take over for this afternoon and evening. A drying trend in
forecast model guidance continues for today, so removed mention of
vicinity showers for KPOU for today. Otherwise, VFR conditions
continue through today for all TAF sites until tonight when fog
could develop at KGFL after 6z.

Winds remain calm through this afternoon then becoming light winds
between 3 and 8 knots to the north to northeast through this evening
before becoming calm again for the overnight hours.

Outlook...

Friday Night: Low Operational Impact. Slight Chance of SHRA.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: Low Operational Impact. Slight Chance of SHRA.
Tuesday: Low Operational Impact. Slight Chance of SHRA.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Speciale
NEAR TERM...Speciale
SHORT TERM...Speciale
LONG TERM...Webb
AVIATION...Webb