086
FXUS61 KLWX 041900
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
300 PM EDT Sat May 4 2024

.SYNOPSIS...
A stalled frontal boundary will remain draped to the south of
the forecast area through tonight before returning north as a
warm front late this weekend. This system will bring on and off
showers and possible thunderstorms. A secondary cold front will
move through the area on Monday before lifting northward as a
warm front on Tuesday. This boundary eventually stalls to the
north by the middle of the week. This will bring a prolonged
period of unsettled weather through much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
After multiple days in the 80s with well above normal
temperatures, today is bringing quite the contrary to the
region. Thanks to a cold air damming signature, an easterly
onshore flow regime has ushered the cool, stable Atlantic air
inland. Temperature gains through the day have been minimal as
most location have not been able to escape the low/mid 50s.
Have continued to favor the coldest pieces of guidance which at
times have not been chilly enough. With the frontal zone down
into North Carolina, the Mid-Atlantic region will remain wedged
in through the remainder of the day.

Underneath the thick low stratus deck, the latest Mid-Atlantic
radar mosaic shows light showers and drizzle pushing toward the
northeast. While the low-level winds are easterly, aircraft
soundings in the area show pronounced southwest to westerly flow
above 3,000 feet. This stable configuration will be maintained
through the remainder of the day. Consequently, thunderstorm
chances were removed given the lack of convective elements in
this regime.

Shortwave energy lifting out of the Tennessee Valley will carry
a more organized batch of showers through the region overnight.
Another quarter to half inch of rain is possible with this next
batch, locally a bit higher in the Blue Ridge Mountains.
Forecast low temperatures stay fairly close to the readings
reported right now. Widespread low to mid 50s are likely with a
few upper 40s possible across northeastern Maryland. Easterly
winds persist which helps maintain that thick area of marine
stratus clouds.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Expect warmer temperatures for Sunday as the mentioned boundary
returns northeastward as a warm front. Model guidance is
notoriously too quick in lifting these boundaries poleward.
Thus, there may be some north-south temperature gradient over
the forecast area where locations near the Mason-Dixon Line
stay much cooler. The current forecast package calls for
mid/upper 60s across northern Maryland and the local mountains.
Meanwhile, low/mid 70s are more commonplace elsewhere. There may
be some breaks in the cloud cover as winds shift from easterly
to south-southeasterly. Where these breaks occur will dictate
where any convective threat resides. For now, have placed a bulk
of the area with a slight chance for afternoon/evening
thunderstorms. Gradually taper off this threat into the
overnight hours as any instability is lost after dark. Some
patchy fog is possible given recent rainfall, decreasing winds,
and a moist boundary layer. Nighttime lows remain mild,
generally staying in the upper 50s to mid 60s.

An approaching cold front ends up on the door step of the local
area on Monday. This system eventually stalls in the vicinity
by late Monday night. Its close proximity to the area will
maintain shower and thunderstorm chances to start off the work
week. However, temperatures should warm up rather markedly with
the Mid-Atlantic fully into the warm sector. Forecast highs are
in the upper 70s to low 80s, locally in the upper 60s to low 70s
across mountain locales. Expect yet another mild night with
lows in the upper 50s to mid 60s. Compared to typical early May
nights, this is around 10 to 15 degrees above normal.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
The unsettled and active weather pattern is likely to continue
through the rest of the week, then possibly dry out next weekend.
Aloft, nearly zonal flow continues as several shortwave troughs
traverse the region. At the surface, a stalled frontal boundary is
likely to be located north of the area, over central to southern PA,
through mid week as a few waves of low pressure move across it.
Moisture and instability are likely to be plentiful each day,
leading to scattered to widespread showers and thunderstorms each
afternoon. Most of the daytime activity dissipates by late evening,
though a few showers could linger through the overnight. There is
some model agreement for drier conditions next weekend as surface
high pressure builds into the region.

The most active period looks to be Wednesday night through Thursday
evening. This is when the strongest mid-level trough of the week and
an associated surface cold front cross the Mid-Atlantic. Our area
should be squarely in the warm sector, with plenty of instability
and moisture available (PWATs over 1.5-1.6" possible). Some strong
to severe storms are possible Thursday as a line of storms develop
along the passing cold front. The better chances for severe storms
look to be east of the Blue Ridge where ample instability and shear
(model soundings indicate 40-50kt of bulk shear) are more likely to
be present. The biggest question mark is whether early morning cloud
cover dissipates in time to allow for better instability to develop.
Moderate to heavy rainfall is also possible areawide, which could
lead to some instances of flooding (though it is also highly
dependent on how much rain falls in the prior days).

Temperatures continue to warm through mid week as highs in the low
80s Tuesday reach the mid to upper 80s Wednesday and Thursday.
Slightly cooler temperatures in the 70s behind the cold front Friday
into Saturday. Very mild overnight lows in the 60s, then cooling a
bit to the 50s Friday night.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
The cold air damming wedge signature is maintaining steady
easterly onshore flow across the area. This is impacting all
terminals with persistent IFR ceilings and visibilities
meandering between IFR and MVFR. Additionally, light showers and
drizzle continue to push northeastward through the area. There
is no threat for any thunderstorms given the stable nature of
the atmosphere. Restrictions will persist through the night and
into a good chunk of Sunday.

A stalled boundary to the south should eventually move across
the area by Sunday afternoon/evening. Once in the more unstable
environment, a few thunderstorms are possible, particularly for
the southern/western TAF sites. A few locations may briefly
return to VFR conditions. However, there is a decent signature
of some patchy fog development on Sunday night. This could bring
additional flight restrictions.

Winds shift from south-southeasterly to southwesterly on Monday.
An approaching cold front may bring additional showers and
thunderstorms to the area. Confidence is low in the spatial
coverage of this convection. VFR conditions should be in place
through most of the day though.

Unsettled weather conditions expected to continue through mid week
as a frontal boundary remains to our north. Scattered to widespread
showers and storms are likely Tuesday afternoon and evening, then
again Wednesday afternoon. Shower/storm activity decreases at night,
though some showers could linger. Any strong shower/storm could
produce brief sub-VFR conditions at any terminal, in addition to
gusty winds and lightning strikes. Outside of shower/storm activity,
VFR conditions are likely.

&&

.MARINE...
Easterly flow is in place across all of the waterways. Small
Craft Advisories are in effect for a majority of the waters
through tonight. While current observations do not show 20 knot
gusts in many locations, these may be a bit sporadic at times.
Some vertical mixing should occur at times given the low-level
thermal gradient formed over the milder waters.

Have opted to continue the Small Craft Advisories through Sunday
afternoon and evening, mainly over the Chesapeake Bay. Winds
will have shifted over to south-southeasterly at this point.
This threat of advisory caliber gusts may persist into Sunday
night over the lower waters. As a warm front approaches from the
south, a few thunderstorms are possible on Sunday, especially
those south of I-66/U.S. 50. Heading into Monday, there will be
a better chance for diurnal thunderstorm activity. Any of the
stronger storms may necessitate Special Marine Warnings.

The active weather pattern continues through mid week as scattered
to widespread showers and thunderstorms move across the local waters
each afternoon/evening. The strongest storms could produce wind
gusts to 35 knots and lightning strikes. Southerly channeling could
result in near-SCA conditions in the open waters of the Chesapeake
Bay Tuesday afternoon/evening. SCA conditions are possible for
several hours Wednesday afternoon over most of the local waters.

&&

.TIDES/COASTAL FLOODING...
Coastal flooding is expected to continue through at least Monday
morning due to persistent east to southeast winds. A Coastal Flood
Warning is in effect for Annapolis and Straits Point tonight as
moderate tidal flooding is expected, and could occur again Sunday
night. Most locations are likely to reach minor flood stage during
the Saturday night to Sunday morning high tide cycle, and once again
during the Sunday night to Monday morning high tide. Coastal Flood
Advisories are in effect, and are likely to be extended and/or
reissued through Sunday night.

Winds turn southwest Monday, though it will likely take time for
water levels to receded as winds vary from southwest to south
through the middle of next week. Additional periods of coastal
flooding are possible.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Advisory until 9 AM EDT Sunday for DCZ001.
MD...Coastal Flood Advisory until 5 PM EDT this afternoon for
     MDZ014.
     Coastal Flood Warning from 11 PM this evening to 8 AM EDT
     Sunday for MDZ014.
     Coastal Flood Warning from 8 PM this evening to 4 AM EDT
     Sunday for MDZ017.
     Coastal Flood Advisory until 3 AM EDT Sunday for MDZ018.
VA...Coastal Flood Advisory until 9 AM EDT Sunday for VAZ054.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for ANZ530-541.
     Small Craft Advisory until 3 PM EDT Sunday for ANZ531-532-
     538>540-542.
     Small Craft Advisory until 6 PM EDT Sunday for ANZ533-534-537-
     543.
     Small Craft Advisory from 6 PM this evening to 6 AM EDT Sunday
     for ANZ536.

&&

$$

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