669
FXUS61 KLWX 121339
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
939 AM EDT Mon Aug 12 2024

.SYNOPSIS...
Surface high pressure builds over the region from the Midwest
through mid to late week. Precipitation chances return for the
end of the week as a low pressure system approaches the area.
This slow moving system maintains an unsettled pattern into
portions of the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...


A northwesterly flow continues to advect in cooler and drier
conditions into the region this morning. Clear to mostly clear
skies are expected to continue through the early afternoon
periods with near average temperatures in the mid 80s.


.Previous Discussion

A surface frontal zone remains stalled across the Carolinas. On
the cool/drier side of this boundary, 07Z/3 AM temperatures have
fallen into the 60s, locally into the mid/upper 50s around the
cooler spots. Across the higher terrain, some locations have
even plunged to around 50 degrees. Within the elongated belt of
cyclonic flow aloft, some mid-level clouds continue to stream
eastward across the area. However, GOES-16 nighttime satellite
imagery does show plenty of breaks in this cloud deck. While not
readily evident on satellite and surface observations, a few
areas of patchy fog are possible across the Potomac Highlands
through just after sunrise.

Through the day, the stalled boundary remains over the Carolinas
while a broad surface high edges eastward from Mississippi River
Valley. The presence of high pressure makes for a quiet start to
the work week. Owing to a light but steady northwesterly wind,
humidity levels remain on the lower side for mid-August
standards. Today`s high temperatures will be in the low/mid 80s,
with 70s across the mountains. Despite passing high clouds at
times, expect plenty of sunshine along with continued
northwesterly winds. With high pressure settling over the area
into the night, winds should go calm allowing for a seasonably
cool night ahead. The forecast calls for low temperatures in the
low/mid 60s, accompanied by mainly mid/upper 50s along and west
of the Blue Ridge Mountains.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A positively-tilted upper trough across New England will exit
into the waters early Tuesday morning. At the same time, the
synoptic-scale pattern yields another round of northwesterly
flow aloft as heights builds across the Great Plains. This
regime will favor continued near to below average temperatures,
reduced humidity levels, and a dry forecast. Within this
northwesterly flow regime, a series of perturbations will track
from the central U.S. toward the Eastern Seaboard. Any such wave
aloft could spark and isolated shower here or there. However,
the dry air mass in place should generally offset any real
threat of shower activity through mid-week.

Tuesday`s forecast highs stay fairly close to the previous day.
A slight warm up is possible by Wednesday given more sunshine.
Given forecast soundings depict mixing up to around 800-775 mb,
could easily see highs being a smidge higher than currently
shown. As of now, the forecast calls for widespread mid 80s
across lower elevations in the area. Mountains locations are
likely in the 70s. Overnight lows stay fairly close to
climatology each night.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
On Thursday, the upper trough over the Northeast will be on its way
out with brief upper ridging building over our area Thursday into
Friday before another trough digs south along the East Coast over
the weekend. The arrival of this second trough is currently progged
to coincide with the exit of surface high pressure to the east and a
low pressure system moving into the Great Lakes/SE Canada.

Mostly dry conditions are expected Thursday and Friday with either
surface high pressure or upper ridging in place. However, guidance
is inconsistent on the strength and placement of the ridge and the
following trough, resulting in some uncertainty. Latest NBM brings
PoPs in by Friday, but 00z guidance continues to trend later with
the arrival of PoPs. For now, limiting PoPs on Friday to chance PoPs
or less, but better chance for rain appears to be Saturday.

Temperatures during the extended are expected to be near or below
normal in the 80s, with lows in the 60s to low 70s.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR conditions are likely through mid-week given the influence
of high pressure over the region. With a frontal zone well to
the south over the Carolinas, surface winds largely stay out of
the northwest. An eventual shift to northerlies is expected by
Wednesday. Afternoon winds may gust up to around 10 knots each
day before subsiding after dark.

VFR conditions are expected Thursday and Friday. Light N/NW flow on
Thursday shifts southerly Thursday night into Friday as surface high
pressure slides east.

&&

.MARINE...
Quiet conditions are expected over the marine waters through
mid-week. While a stray shower here or there is possible at some
point, high pressure should maintain a mainly dry pattern. Winds
stay out of the north to northwest, accompanied by gusts staying
around 10 knots or less.

No hazardous marine conditions are expected Thursday and Friday.
Light N/NW winds over the waters on Thursday shift southerly
Thursday night into Friday as surface high pressure slides east.
Winds could pick up on Friday with southerly channeling, but the
arrival of the next system has been trending later, so winds aren`t
currently expected to approach SCA criteria until Saturday.

&&

.TIDES/COASTAL FLOODING...
With current tidal anomalies generally averaging between 0.25 to
0.50 feet, water levels remain below Action Stage at the local
sites. This should stay that way given persist northwesterly
winds. A gradual ramp up is possible at more sensitive locations
by later in the week.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO/JMG
SHORT TERM...BRO
LONG TERM...CAS
AVIATION...BRO/CAS
MARINE...BRO/CAS
TIDES/COASTAL FLOODING...