431
FXUS61 KLWX 141346
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
946 AM EDT Wed Aug 14 2024

.SYNOPSIS...
Hazy skies today as smoke from Canadian wildfires pushes south
around an area of broad high pressure overhead. Quiet weather
conditions are expected otherwise through Thursday before
precipitation chances return with a slow moving low pressure system
Friday into the weekend. A cold front will cross the region late
Saturday into Sunday bringing the highest probability for showers
and thunderstorms.This system exits off the coast Monday into
Tuesday with high pressure set to return to the region by the middle
of next week.


&&

.NEAR TERM /THROUGH TONIGHT/...
Upper level troughing will continue to exit off the Atlantic coast
today while broad high pressure builds eastward from the Great Lakes
region. Tranquil weather conditions are expected as a result with
less cloud cover and low humidity. Highs today will rise into the
low to mid 80s east of the Alleghenies with 70s along the higher
ridges.

One thing to note will be some Canadian wildfire smoke in
the mid to upper troposphere. This smoke is evident on the GOES
GeoColor this morning with a subtle band dropping in from central PA
and southern NJ. High-resolution smoke guidance also picks up on
this with northerly flow carrying this elevated smoke plume through
the area mid to late afternoon. Consequently, have opted to put haze
in the forecast grids for areas along and east of U.S. 15 starting
midday and through at least sunset. While this could impact
locations to the west, confidence was not high enough to do so.
Smoke is unlikely to affect the surface, although some minor
reductions in visibility (5-7SM) are possible throughout the mid to
late afternoon period.

High pressure will rule the forecast tonight with plenty of
subsidence overhead. Looking like a good radiational cooling set up
with mainly clear skies and calm winds. This will allow temperatures
to fall into the low to mid 60s east of the Blue RIdge with 50s
west. Mountain and high valley locations could fall back into the
40s. Patchy river/valley fog is possible heading into daybreak
Thursday.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
With longwave ridging across the area on Thursday, expect one
more dry day ahead of a wetter period ahead. Additionally, the
typical summertime humidity is also held at bay owing to a
persistent north to northwesterly wind. High temperatures push
into the upper 80s with a few 90 degree readings possible. While
skies start off relatively clear, expect increasing clouds late
in the day ahead of the next weather maker. As this occurs,
winds eventually shift to southerly which yields a gradual
moistening of the lower atmosphere. Eventually some showers work
their way to the Alleghenies by late Thursday night. Overnight
lows will be in the 60s although some low 70s are likely across
D.C. and Baltimore.

On Friday, the approaching longwave trough is forecast to be
located over the Upper Great Lakes with the associated frontal
systems nearing the Ohio Valley. Broad ascent ahead of these
height falls will continue to spread increasing clouds across
the Mid-Atlantic region. The latest timing keeps the bulk of the
showers and embedded thunderstorms west of I-95 before dark.
Heading into the late evening and night, this activity begins to
overspread the entire forecast area. Conditions will also be
milder as a warm front pushes through overnight. Low temperatures
are to range from the mid 60s to low 70s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As a trough digs into the Ohio Valley/Mid-Atlantic Saturday, surface
high pressure slides off to the east and a low pressure system moves
into the Great Lakes.

By Saturday, we`ll be in the warm sector of the low passing to our
north, with ample moisture from persistent southerly flow. Combined
with ascent from the approaching trough, widespread chance to likely
PoPs are expected Saturday afternoon/evening.

The cold front is currently expected to move through between
Saturday evening and Sunday. More widespread showers and
thunderstorms can be expected with the frontal passage. Surface high
pressure is expected to build in behind the cold front on Monday
into Tuesday, but some showers could continue west of the Blue Ridge
as a trailing shortwave acts on lingering moisture.

Temperatures Saturday are expected to be in the mid-upper 80s for
most of the area. Only a few degrees of cooling is anticipated
behind the cold front Sunday into early next week. Lows will be in
the 60s and 70s outside of the mountains for the duration of the
extended.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are likely across all terminals through Thursday
and perhaps the first half of Friday. Some elevated smoke could
impact some terminals today, but do not expect any large
reductions in the visibility. Winds shift over to northerly
today with a few afternoon gusts up to 15 knots. Similar winds
are expected on Thursday, but they should be much lighter in
nature.

By late Thursday evening, southerly warm advection returns.
Gusts on Friday could push into the 10 to 15 knot range,
accompanied by increasing rain chances from the evening onward.
This may come with a few rumbles of thunder as well. Sub-VFR
conditions are possible Friday evening and into the night given
the threat for showers.

While VFR conditions are expected to prevail most of the weekend,
showers and thunderstorms could bring brief restrictions to
terminals, especially in the afternoon and evening hours. Winds
increase out of the south Saturday with gusts to around 15 kts are
possible in the afternoon. Behind the cold front on Sunday winds
turn W/NW.

&&

.MARINE...
A fairly persistent northerly wind continues the next couple of
days. Any gusts should top out in the 10 to 15 knot range. A
shift to southerlies is expected late Thursday into Friday. This
will also lead to a period of southerly channeling, especially
Friday evening into the overnight hours. Small Craft Advisories
may be needed across portions of the waters. Additionally,
showers and few thunderstorms may also impact the waters by late
Friday.

Winds increase out of the south Saturday and could approach SCA
criteria, especially in the open waters of the central and southern
Bay. Winds diminish and turn W/NW behind a cold front on Sunday.

&&

.TIDES/COASTAL FLOODING...
Tidal anomalies remain low under light N/NW flow. However, a few
sensitive sites may approach or reach Action stage during the next
few late night/early morning high tide cycles, such as Havre de
Grace and Annapolis. Winds turn southerly late this week behind a
warm front and increase tidal anomalies. As a result, some sensitive
locations may approach Minor flooding.

&&

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

&&

$$

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