301
FXUS61 KAKQ 080005
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
805 PM EDT Tue May 7 2024

.SYNOPSIS...
Summer-like conditions with daily showers and storms are
expected through Thursday, with a cold front expected to push
through the region late Thursday through Friday. An upper level
trough will keep a chance for showers late Saturday into Sunday,
with dry conditions expected Monday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 300 PM EDT Tuesday...

Midday sfc analysis shows a weak frontal boundary across the
Delmarva region, with high pressure well offshore. Aloft, shortwave
energy is located near the NC OBX while a ridge axis extends from
the Deep South northward into the Great Lakes vicinity. These
features will be the main focus for shower and tstm activity through
the rest of this afternoon into early tonight. Additionally, given
the weak sfc flow, sea breezes are likely to develop and move inland
over the next few hrs, which could serve as triggers for additional
convection. Coverage overall should be less than yesterday given
broad-scale subsidence from the ridge aloft and less lee troughing.
CAMs generally focus most of the convection along the I-64 corridor
and on the MD Eastern Shore, with perhaps a few stray cells
impinging on our wrn CWA border this evening. PoPs are 20-40%.
Steepening low-level lapse rates and decent instability (1000-1500
J/kg of MLCAPE) argue for the potential for localized damaging wind
gusts and marginally severe hail. Heavy rain could also pose a risk
of isolated flash flooding given many areas have received a 1-3" of
rain over the past few days. SPC maintains a marginal risk for svr
wx for most of the area. High temps this aftn should top out around
in the mid-upper 70s NE to the low-mid 80s SW. On the Northern Neck,
persistent low cloud cover has prevented robust sfc heating and
highs may underperform a few degrees there. Storms dissipate shortly
after sunset given the loss of sfc heating. Will need to keep an eye
on any upstream convective complexes from the OH River Valley
tonight as some CAMs hint at some residual echoes clipping nrn
portions of the FA. This scenario remains highly uncertain so will
keep PoPs low at this time.

There also is a strong signal for marine fog moving inland onto
at least the ern half of the MD Eastern Shore tonight.
Visibilities could drop below a 1/2 mile at times. Overnight
lows will be mild and in the mid 60s for most of the area (upper
50s along the Atlantic coast of the ern shore).

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
As of 300 PM EDT Tuesday...

While the ridge flattens some into Wednesday, low-level thicknesses
will be at their greatest, favoring the hottest temps of the week.
Most guidance agrees on nearly everywhere flirting w/ 90 degrees
with some output even suggesting a few sites reaching 92-93F. Even
those on the eastern shore should reach the upper 80s. Given dew
points in the 60s (low 60s NW/mid-upper 60s SE), aftn heat indices
approach the mid and potentially upper 90s. The other story will be
continued chances for afternoon/evening thunderstorms. With a strong
upper low shifting E towards the Great Lakes and an approaching (but
flattening) mid/upper trough, stronger flow aloft is forecast to
overspread the FA. Area-averaged soundings show more than adequate
bulk shear to support svr wx (~40 kt). Additionally, the
aforementioned heat/humidity will favor moderate-strong instability
with MLCAPE 2000+ J/kg in the aftn, highest across the S/SE. The one
caveat is we again are lacking a prominent trigger for storms w/ the
WSW sfc flow and ridge aloft, so may have to again rely on residual
boundaries or upstream perturbations to spark convection. SPC has
upgraded the SW half of the area to a slight risk, which is where
the highest confidence resides regarding convective coverage and
strong instability. Would not be surprised to see this expanded to
the rest of the FA in future updates. Steep low and relatively steep
mid-level lapse rates argue for both large hail and damaging winds
as the primary threats from any storm that can develop. Convection
may linger into the evening and overnight as instability will be
slow to wane. Also, there is a better signal in the guidance that a
mesoscale convective system (or its remnants) will move through at
some point Wed night, which explains the elevated overnight and
early morning PoPs. Overnight lows will be in the mid-upper 60s.

The highest coverage of severe wx is expected Thursday as even
stronger flow aloft overspreads the region and a sfc cold front
approaches from the W. Aloft, the approaching upper trough will
induce height falls and provide more widespread forcing for ascent.
SPC has a slight risk for the entire area. Some of the CAMs continue
to suggest prior-day shower/storm activity may linger into the
morning hrs Thursday, which could mess with the aftn instability to
some extent. However, it is notoriously difficult to time these
features (even in the <24 hr timeframe) and the models tend to
perform poorly in their development and evolution. Damaging winds
and large hail continue to look like the most likely threats from
any storm. Given the frontal forcing, it seems probable that storms
would eventually grow upscale in a linear-type feature, with
widespread damaging winds becoming increasingly favored. Low-level
hodograph curvature is also somewhat enhanced near the front, though
high LCLs would argue against a robust tornado threat. With more
clouds around, high temps will be cooler and generally in the 80s
(warmest S/SE, coolest N). Also cooler Thu night with lows in the
upper 50s-low 60s.

Friday starts off mainly dry, but scattered showers are expected to
redevelop as the upper trough swings through and the associated
shortwave moves across either VA or the Carolinas. There will be
limited sfc-based instability but the cold pool aloft could set off
some tstms, mainly across the southern 1/2 of the CWA. At this time,
severe wx is not expected. Highs on Fri will be cooler, mainly in
the lower to mid 70s (upper 70s possible far S).

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 300 PM EDT Tuesday...

There remains some uncertainty for both Friday night and
through the weekend. The 12z deterministic GFS continues to
phase the upper trough with srn stream energy Fri night (this is
because it is slower and more amplified with the trough). This
leads to sfc low pressure formation along the baroclinic zone
just offshore of the Carolinas. Such a scenario would push
widespread stratiform rainfall N towards the FA Fri evening and
overnight. The 12z ECMWF suppresses this feature further S as it
is depicts a more neutral trough tilt. At this time, will keep
the highest PoPs across the SE assuming the sfc low passes well
to our S. Beyond this, the weekend weather pattern will feature
yet another upper trough diving SE from the Great Lakes and
passing off the mid-Atlantic coast Sat night through Sunday. The
airmass will be cooler and fairly dry but will continue w/
20-30% PoPs (highest N) for Sat night through early Sun aftn. It
looks mainly dry from late Sunday through Tuesday with
seasonable temperatures (highs in the 70s with lows in the upper
40s to mid 50s), potentially warming further into the middle of
next week.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 800 PM EDT Tuesday...

VFR conditions at all TAF sites to start off the forecast
period. Low stratus and patchy fog develops later this
evening/tonight (mainly after 03z) at SBY resulting in sub-VFR
conditions. Confidence is not overly high in regards to how far
inland the lower CIGs will make it, though moisture from today`s
rainfall may aide in patchy fog formation at SBY. All other
sites remain VFR through tonight. VFR conditions are expected
through the day Wednesday outside of any scattered afternoon
showers or thunderstorms (highest chances across the southern
TAF sites). Winds will primarily be light and out of the SW
tonight (variable early tonight closer to the coast), increasing
to around 10 knots by Wednesday afternoon.

Outlook...A warmer, more summerlike pattern will prevail
through Thu, with chances for storms mainly during the
aftn/evening. The highest coverage is expected to be Thursday as
a slow moving cold front moves through the area. Svr wx is
possible. Mainly VFR Fri, but there will be a chc for showers
redeveloping Fri aftn into fri evening. Mainly dry Sat.

&&

.MARINE...
As of 250 PM EDT Tuesday...

Latest analysis continues to show a quasi-stationary frontal
boundary draped across the northern mid-Atlantic, with 1018+mb
surface high pressure centered south of Bermuda. A weak lee trough
continues to sharpen west of the waters, allowing for S-SW winds
over the region ~10-12 kt. Waves 1-2 ft, with seas generally 2 to
4ft with some weak E-SE swell at 8-10 seconds.

High pressure remains anchored well offshore through mid week, with
(sub-SCA) S-SW flow also persisting throughout the midweek period. A
series of upper waves traverse north of the area, and bring the
chance for showers and thunderstorms. Timing will continue to favor
the late afternoon/evening into the early overnight hours. Locally
enhanced winds/waves/seas could accompany the stronger storms. A
stronger low approaching from the W-SW with the trailing cold
frontal passage crossing the waters Friday morning/afternoon. Winds
quickly veer to the W-NW post-frontal Friday afternoon. A brief CAA
surge could bring a brief window of SCAs to the Bay and lower James
Friday night, with winds then diminishing through the day Saturday.
Winds quickly veer back to the SSW again Saturday night and Sunday
ahead of another weaker front. That front crosses Sunday night, with
winds eventually veering back to the NNW Sunday night and into early
next week. Aside from enhanced winds/seas in convection over the
next few days and a brief period of potential SCA-level winds Friday
night, conditions remain largely Sub-SCA through the period. Waves
generally 1-2 ft with seas 2-4 ft through the end of the work week.
week.

&&

.TIDES/COASTAL FLOODING...
As of 250 PM EDT Tuesday...

The upcoming new moon cycle and the Perigee from this past weekend
will lead to continued positive tidal anomalies over the next few
days. Given the ongoing light southerly flow, some nuisance to low-
end minor coastal flood impacts are possible for coastal communities
along the upper portions of the Chesapeake Bay and tidal Potomac
River during the upcoming astronomically higher high tide cycle late
this evening into Wednesday morning. Added some Coastal Flood
Advisories for Lancaster and Northumberland Counties (Lewisetta) and
from Accomack VA north to Somerset, Dorchester, and Wicomico (MD)
counties on the bay side of the eastern shore. Potential for some
additional nuisance to near minor water levels over the next
couple of days before tidal anomalies ease later this week.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Advisory from 11 PM this evening to 6 AM EDT
     Wednesday for MDZ021>023.
NC...None.
VA...Coastal Flood Advisory from 11 PM this evening to 6 AM EDT
     Wednesday for VAZ077-078-099.
MARINE...None.

&&

$$

SYNOPSIS...LKB/SW
NEAR TERM...SW
SHORT TERM...SW
LONG TERM...LKB/SW
AVIATION...AJB/SW
MARINE...MAM
TIDES/COASTAL FLOODING...