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825
FXUS61 KLWX 151757
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
157 PM EDT Wed May 15 2024

.SYNOPSIS...
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A low pressure system and its associated front will continue to
cross the Mid-Atlantic today. Weak area of high pressure builds in
on Thursday into Friday, leading to drier conditions compared to the
previous days. Another slow moving low pressure system will bring
additional shower and thunderstorm chances for the weekend before
weak high pressure returns early next week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Two areas of low pressure are impacting the Mid-Atlantic this
afternoon, one off to the west and another off the SE VA coast.
Showers associated with the coastal low have begun to dissipate
from west to east. There have even been some light breaks in the
clouds as a result of the departing low. The upper trough will
continue to move further east and allow for showers to continue
from the west. In central VA and along the Allegheny Front,
clouds may break enough to allow some instability to build in
and create a chance for an isolated thunderstorm. Otherwise,
areas of showers and drizzle will persist throughout the day
with highs only topping out in the low to mid 60s for the most
part.

By tonight, the upper trough will continue to absorb the coastal
low, allowing it to stall further off the coast. Rain chances will
begin to decrease except right along the Chesapeake where these
chances may hold on through the night. With any breaks in the clouds
overnight, fog may develop as we head into Thursday morning.
Overnight lows will bottom out in the low to mid 50s.
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&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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The low will continue to linger around the coast on Thursday,
keeping more clouds around the I-95 corridor with ridging building
in further west. While most places will be mostly dry throughout the
day, cannot rule out a few isolated showers with any lingering low-
level moisture around as a result of the departing low. Highs will
be tricky, as areas that receive more breaks in the clouds will
likely top out in the mid to upper 70s, whereas places with more
clouds will be in the upper 60s to low 70s during the afternoon and
early evening hours. Ridging will build more overhead by Thursday
night, allowing drier conditions and lows in the 50s for most areas.

The next system will approach the area on Friday, increasing clouds
and precipitation chances, especially along and west of the Blue
Ridge. Cannot rule out an isolated thunderstorm. Highs will be in
the mid to upper 70s. Moisture increases by Friday night with
increased rain chances and lows dipping down into the mid to upper
50s.
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&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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Overall the long term period looks to remain quite
unsettled for the most part, with a brief respite likely towards the
beginning of next week between areas of low pressure.

For the weekend, unfortunately it looks to be another wet one with
high temperatures in the mid to upper 60s on both days. This is due
to a slow-moving trough that will be working its way eastward across
the southern CONUS. The majority of shower and thunderstorm activity
should occur on Saturday, but as the surface low associated with
this system reaches the coast, it seems to slow down and some
guidance even nearly stalls it off the Mid-Atlantic coast on Sunday.

By early next week, as the aforementioned low moves well off to our
east, a ridge aloft builds in from the west. This will bring warmer
and drier conditions back to the region. However, neither day poses
a non-zero chance for thunderstorms. Pieces of upper-level energy
will be sliding across the north side of the ridge, thus bringing at
least a small chance for some afternoon storms.

By mid-week, we may have our next organized system moving through.
Whether that is Wednesday or Thursday is still a bit up in the air,
but the combination of much warmer temperatures by then (likely in
the low 80s or so) and higher humidity should yield a better chance
of organized thunderstorm activity. This would likely come in the
form of thunderstorms developing over the higher terrain during peak
heating, before drifting eastward into the afternoon/evening hours.
We will be a bit more confident on that potential, as well as any
severe weather potential, as we get a bit closer in time.
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&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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MVFR ceilings will be more common this afternoon, with decreasing
coverage of rain and drizzle for the terminals. Easterly winds will
become more northerly this evening, which should allow for drier
conditions. However, MVFR to IFR ceilings will likely persist with
the low lingering off the coast. Some breaks in the clouds could
occur at MRB, which could lead to fog.

Low ceilings should gradually lift Thursday and could scatter out in
some locations. However, there are indications low ceilings and/or
fog may redevelop Thursday night into Friday morning. The next
system will be approach late Friday, increasing the chance for
showers and sub-VFR ceilings, especially Friday night.

An area of low pressure will slowly traverse the region Saturday
into Sunday, bringing unsettled conditions to the terminals.
Sub-VFR conditions are likely during this time due to lowered
CIGs and potential VSBY restrictions in heavier rain and/or
thunderstorms.
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&&

.MARINE...
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SCAs are in effect for most of the waters aside from the northern-
most Potomac zone through this evening. The low will remain off the
coast tonight into Thursday. An advisory will remain in effect for
the bay and lower Potomac through the night as winds become more
northerly. Deeper mixing should ensue Thursday with the wind field
still in place, so the SCA will expand to all waters. Winds are
forecast to gradually diminish Thursday night, but the advisory will
likely need to be extended for some zones. Overall, lighter winds
are expected Friday and Friday night as weak high pressure moves
across the area.

A brief period of SCA conditions remain possible Saturday afternoon
into Saturday night as an area of low pressure passes just south of
the region. This will be especially true over middle and lower
portions of the bay and lower tidal Potomac where a bit more
channeling could occur. Numerous showers and perhaps a few
thunderstorms will accompany this system through Saturday into early
Sunday.

Onshore easterly flow is expected on Saturday ahead of an
approaching area of low pressure, and should be close to SCA
criteria. Winds Saturday night into Sunday will gradually shift to
north-northeasterly as the low slides across the region. Again,
would expect winds to be at or near SCA criteria during this time.
This will especially be true across lower portions of the
waters.
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&&

.TIDES/COASTAL FLOODING...
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Easterly winds will keep water levels elevated in the Chesapeake Bay
and Tidal Potomac through this afternoon.

As an area of low pressure moves east of the area later today, winds
become northeast, then north. This should result in quickly
decreasing water levels and reduced coastal flood threat.

Beyond today, the next threat for coastal flooding appears to be
Friday into the weekend as south to southeasterly flow returns ahead
of an approaching low pressure system from the Ohio River
Valley.
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Coastal Flood Advisory until 5 PM EDT this afternoon for
     DCZ001.
MD...Coastal Flood Advisory until 3 PM EDT this afternoon for
     MDZ014.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT Thursday for ANZ530>534-
     537-539>541-543.
     Small Craft Advisory from 8 AM to 6 PM EDT Thursday for ANZ535-
     536-538-542.
     Small Craft Advisory until 6 PM EDT this evening for ANZ536-
     538-542.
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&&

$$

SYNOPSIS...ADM/EST
NEAR TERM...ADM
SHORT TERM...ADS/ADM
LONG TERM...CJL
AVIATION...ADS/CJL/ADM
MARINE...ADS/CJL/ADM
TIDES/COASTAL FLOODING...LWX