637
FXUS61 KAKQ 212008
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
408 PM EDT Sat Sep 21 2024

.SYNOPSIS...
High pressure builds south along the Mid-Atlantic coast into
early next week. Meanwhile, a series of shortwave troughs will
slide across the region in northwest flow aloft bringing on and
off rain chances. Seasonal temperatures are expected to start
next week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 335 PM EDT Saturday...

Key Messages:

- Pleasant weather this afternoon with highs in the low 80s
  inland, 70s immediately near the coast.

- Shower/storm chances increase late this afternoon in the
  west, progress east overnight. A severe storm or two possible
  in the piedmont.

Mostly sunny this afternoon with high pressure centered well N
of the region and ridging S along the Mid-Atlantic coast.
Temperatures range from the upper 70s to lower 80s. Meanwhile,
showers/tstms are developing across the higher terrain to the W
ahead of a shortwave trough and approaching cold front.21/12z
CAMs remain in good agreement regarding timing and coverage of
precip spreading across western portions of the area late this
afternoon and evening. Scattered showers/storms then gradually
cross the area overnight as secondary shortwave energy slides
across the area. SPC has far western portions of the area in a
MGNL for today. There will be decent shear in the area, as the
12z HREF shows ~30-35kt of effective shear. However, the window
for severe weather will be limited given the narrow timeframe
for sufficient CAPE prior to sunset. If severe tstms do form,
the threats would be damaging wind gusts and hail. A weak
backdoor cold front pushes onshore late tonight. There is a
potential for stratus late tonight, and some patchy fog across
the Piedmont. Low temperatures will primarily be in the 60s.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
As of 335 PM EDT Saturday...

Key Messages:

- Isolated shower chances for Sunday with a backdoor cold front

- Pleasant start to the week with dry weather and highs in the
  70s

The backdoor cold front is forecast to cross into the local
area early Sunday morning and lingers in the area through the
day. Isolated/widely scattered showers will accompany the front,
so slight chance PoPs have been maintained in the NE early then
progressing SW through the day. High temperatures will depend
on the location of the front through the day, but generally
expect low-mid 70s in the NE and around 80F in the SW. Mostly
cloudy to overcast conditions are expected across most of the
area.

The ridge axis aloft shifts toward the E coast Monday.
Meanwhile, surface low pressure offshore finally makes some
progress to the SE and farther offshore. Monday should be
pleasant, albeit a bit cloudy. Highs will be in the low-mid 70s
across northern counties and upper 70s S of I-64. Lows Mon night
will be around 60. Another shortwave trough approaches from the
NW Tuesday as high pressure remains centered NE of the region
with the surface ridge axis extending SW along the Mid-Atlantic
coast. This will bring a chc of showers inland. High
temperatures range from the lower 70s NW to the upper 70s SE,
after morning lows in the lower to mid 60s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 335 PM EDT Saturday...

Key Messages:

- Multiple low-end chances for precip next week.

Moisture will gradually slide back into the area next week
around the edge of a ridge offshore, and ahead of a trough well
to the W. Confidence in the forecast for midweek and after is
low, but there are daily rain chances with increased moisture.
Temperatures will gradually warm a bit as thicknesses rise with
the ridge pushing up the coastline. Highs are forecast to be in
the mid 70s to around 80 degrees. Lows will mainly be in the
60s.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
As of 210 PM EDT Saturday...

Surface high pressure remains over the region as of 18z between
low pressure offshore and a cold front over the upper Ohio
Valley. FEW-SCT CU with bases of 3-4kft and a light and variable
wind. The cold front and an upper trough will approach from the
NW later this aftn and evening. Then a backdoor cold front will
slide in from the NE late tonight into early Sunday morning. The
best chc of showers/tstms will be at RIC this evening and mainly
after 23z. Brief heavy rain and reduced vsby along with locally
strong wind gusts are possible with any tstms. A chc of showers
and perhaps a tstm will shift E later tonight, mainly after 04z.
There is a potential for MVFR and IFR cigs late tonight into
Sunday morning, with the best potential for IFR cigs at RIC.
Additionally, MVFR vsby is possible. The backdoor cold front
will slide across the region Sunday. MVFR cigs potentially
linger into late morning and early aftn, with VFR by late aftn.
The wind will mainly be ENE 8-12kt behind the backdoor front.

There is a potential for lower cigs late Sunday night/early
Monday morning. Otherwise, mainly dry and VFR Monday. Minimal
chcs of showers are forecast Tuesday through Thursday.

&&

.MARINE...
As of 405 PM EDT Saturday...

Key Messages:

- Small Craft Advisories remain in effect for all coastal waters
  through Monday (primarily for seas).

- Winds increase Sunday, but remain mainly sub-SCA. Waves may
  build to 4 ft late Sunday/Sunday night at the mouth of the
  Bay.

- Persistent long period swells keep seas elevated into the
  middle of next week.

Sfc low pressure (~1007mb) lingers well off the southern New
England and NJ coast, with high pressure centered well to the N,
across NewFoundland/Labrador. SE winds ~10 kt (10-15 kt across
the bay) continue into this evening, diminishing to 5-10 kt
overnight. Winds become E 10-15 kt with perhaps a few gusts to
around 20 kt Sun behind a weak area of low pressure which moves
SE across VA and into E NC. Winds become NE 15-20 kt across the
coastal waters and lower bay (15 kt with a few gusts to around
20 kt for the rest of the bay) Sun evening into early Sun night
before diminishing to 10-15 kt. Cannot rule out a few gusts up
to 25 kt across the northern coastal waters. Waves and seas were
1-2 ft (2-3 ft at the mouth of the bay) and 4-5 ft respectively
this afternoon. Expect seas to build to 5-7 ft Sun night into
Mon, potentially remaining elevated through mid week. As such,
have maintained SCAs for the coastal waters until Mon evening.
Will note that these SCAs will need to be extended in future
updates. Confidence is still too low for any headlines (outside
of 3-4 ft waves at the mouth of the Ches Bay).

&&

.TIDES/COASTAL FLOODING...
As of 400 PM Saturday...

- Key Message: Long duration coastal flood event continues
  across the region, with flooding likely to persist through mid
  week. Various headlines remain in effect (see latest CFWAKQ
  for details).

Tidal departures have risen slightly over the past 12 hrs, with
some areas now >+1.5 ft above astro tide levels. This
afternoon`s high tide cycle is the higher of the daily cycle
(astronomically), which will lead to water levels into moderate
flood thresholds for most sites in the mid/upper Bay, as well as
the VA eastern shore. Va Beach and Currituck, NC peaked at right
around moderate flood stage. The high tides Sunday and Monday
afternoon look to be slightly higher than this afternoon`s high
tide. As such, expect additional rounds of moderate coastal
flooding through Monday evening. Portions of the upper bay may
see moderate coastal flooding continue into Tuesday. For now,
have issued Coastal Flood Warnings for most of the Chesapeake
Bay, Virginia Beach, Currituck, and Eastern Shore (apart from
around Ocean City, MD) through Monday evening. Confidence was
too low at Yorktown to extend the Coastal Flood Warning beyond
Sunday, but this may need to be extended in future updates. Have
opted to leave Norfolk and Chesapeake in a Coastal Flood
Advisory (as opposed to a Coastal Flood Warning) given that the
Elizabeth River and Swell`s Point look to remain below moderate
flood stage. However, if tides trend up, they may need to be
added to the warning. A Coastal Flood Advisory remains across
the Atlantic side of the Maryland Eastern Shore with Ocean City
looking to remain in minor flood stage through Monday afternoon.
Additional coastal flooding looks to continue into mid week.

In addition, a High rip current risk is in effect through
Sunday and will likely be extended into Monday as well.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Warning until midnight EDT Monday night for
     MDZ021>023.
     Coastal Flood Advisory until 4 PM EDT Monday for MDZ024-025.
NC...Coastal Flood Warning until 4 PM EDT Sunday for NCZ102.
VA...Coastal Flood Warning until midnight EDT Monday night for
     VAZ075-077.
     Coastal Flood Warning until 4 PM EDT Sunday for VAZ098.
     Coastal Flood Warning until 10 PM EDT Monday for VAZ076-078-
     085-521-522.
     Coastal Flood Advisory until 8 PM EDT Monday for VAZ083-518-
     520.
     Coastal Flood Advisory until 4 AM EDT Sunday for VAZ084-086-
     523.
     Coastal Flood Warning from 11 AM to 6 PM EDT Sunday for VAZ084-
     086-523>525.
     Coastal Flood Advisory until 6 AM EDT Sunday for VAZ089-090-
     093-096-524-525.
     Coastal Flood Warning from 11 AM Sunday to 10 PM EDT Monday
     for VAZ089-090-093-096.
     Coastal Flood Advisory until 6 PM EDT Monday for VAZ095-097.
     Coastal Flood Warning until 8 PM EDT Monday for VAZ099-100.
MARINE...Small Craft Advisory until 6 PM EDT Monday for ANZ650-652-654-
     656-658.

&&

$$

SYNOPSIS...AJZ/AM
NEAR TERM...AJZ/AM
SHORT TERM...AJZ/AM
LONG TERM...AJZ/AM
AVIATION...AJZ
MARINE...LKB/RMM
TIDES/COASTAL FLOODING...