280
FXUS61 KAKQ 231934
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
334 PM EDT Mon Sep 23 2024

.SYNOPSIS...
High pressure builds south along the Mid-Atlantic coast early
this week. Meanwhile, a series of shortwave troughs will slide
across the region in northwest flow aloft bringing unsettled
conditions through midweek. Temperatures will be on the cool
side of seasonal averages Tuesday and gradually moderate through
midweek.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 330 PM EDT Monday...

Key Message:

- A chance for showers tonight, especially west of I-95.

- A chance for showers lingers into Tuesday morning.

GOES water vapor channels depict a building ridge over the Ohio
Valley with an upper low drifting SE well offshore. At the
surface, 1022mb high pressure is centered over Atlantic Canada
and continues to ridge to the SW along the Mid-Atlantic coast.
The backdoor cold front from yesterday has become rather
diffuse, but is still noted by stratus over western NC and NW
SC. Mostly cloudy this afternoon across the NW 2/3rds of the
area, and partly sunny SE. There are some light
showers/sprinkles from N and NW of the RIC metro to the Northern
Neck and MD Eastern Shore associated with some shortwave energy
sliding across the northern Mid-Atlantic. Temperatures are
primarily in the lower to mid 70s.

The upper ridge axis shifts toward the Mid-Atlantic coast
tonight into Tuesday with additional shortwave energy rounding
the northern periphery of the ridge. Showers potentially move
into the Piedmont this evening, then scattered showers develop
along and W of the I-95 corridor overnight into Tuesday morning.
PoPs diminish Tuesday afternoon as shortwave energy lifts NE of
the local area. QPF overnight into Tuesday is generally
0.1-0.25" but some locally higher amounts are possible. A few
rumbles of thunder are possible over the SW Piedmont with some
elevated instability. Mostly cloudy to overcast tonight into
Tuesday. Lows tonight are mainly in the lower to mid 60s.
Considerable cloud cover will keep highs in the upper 60s to
around 70F over the NW Piedmont Tuesday, with lower to mid 70s
elsewhere.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 330 PM EDT Monday...

Key Messages:

- Cloudy with multiple chances for showers, primarily west of
  I-95.

The upper ridge axis moves offshore Tuesday night into
Wednesday allowing deeper SW flow to develop over the Mid-
Atlantic, with a closed anticyclone developing offshore. This
should allow the residual boundary to lift N and the surface
high should nudge offshore. Additional shortwave energy will
bring a chc of showers and embedded tstms Tuesday night. Higher
rain rates are possible with this system given deeper moisture,
especially over the Piedmont. Current storm total QPF (including
tonight into Tuesday morning) is generally 0.4-0.6" W of the
I-95 corridor, but higher amounts are certainly possible. Lows
Tuesday night are mainly in the 60s. Warmer and more humid
Wednesday with highs ranging from the mid 70s NE to the lower
80s SE. The closed upper high eventually links with a ridge over
the Midwest Wednesday night into Thursday between the potential
tropical cyclone over the Gulf and a trough over the Saint
Lawrence Valley. This will result in diminished rain chances.
Lows Wednesday night will mainly be in the mid to upper 60s,
followed by highs Thursday in the upper 70s to lower 80s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 330 PM EDT Monday...

Key Message:

- Multiple low-end chances for rain late this week from the
potential development of a tropical system in the Gulf of Mexico.

Friday has the highest rain chances (especially to the SW of
the local area) around 40-50%. There is some uncertainty on
direct impacts as the rainfall will be correlated to the
current low pressure system building in the Caribbean Sea that
is likely to become a tropical system. There is decent model
agreement on the cutoff low over the midwest absorbing the
potentially tropical low pressure. This could keep the bulk of
the rainfall to the local area`s SW. It is still too early to
determine impacts to the local area at this time.

The majority of the area on Saturday and Sunday have a slight chc of
showers. Temperatures won`t feel like autumn yet with highs in the
upper 70s on Saturday and mid 70s on Sunday and Monday.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
As of 200 PM EDT Monday...

VFR conditions will continue for the remainder of the day and early
overnight. Patches of fog will begin to develop towards the VA
piedmont region overnight. RIC will have MVFR to IFR conditions in
the early morning. As for the rest of the major terminals, VFR
conditions will remain. Winds tonight and in the morning are from
the E at 5-10kt.

Chc of showers increases overnight into Wednesday(especially
inland). MVFR and locally IFR flight restrictions are possible with
the chance of rain Tuesday and Wednesday. Thursday will be drier,
but chc of showers returns on Friday.&&

.MARINE...
As of 330 PM EDT Monday...

Key Messages:

- Small Craft Advisories remain in effect for all coastal
  waters through Wed due to elevated seas.

- Persistent long period swells keep seas elevated through this
  week.

- Southeast to northeast winds may become elevated this
  weekend.

Low pressure continues to linger well off the East Coast, with
a strong high pressure over New Brunswick this afternoon. Winds
this afternoon were generally E/NE ~10 kt. E/ESE winds briefly
increase to 10-15 kt this evening across the Ches Bay and rivers
before diminishing overnight. Winds will be nearly the same as
today for Tue with a brief surge to ~15 kt with a few gusts up
to 20 kt possible in the late afternoon/evening. Winds then
remain generally SE 5-10 kt through Thu night before increasing
to 10-15 kt with gusts up to 20 kt Fri. Forecast uncertainty
increases Fri into the weekend as the winds will depend on how
Potential Tropical Cyclone Nine (PTC 9) interacts with a large
cutoff low moving into the MS Valley. The exact strength and
track of both the tropical system and the cutoff low will be key
to determining the local impacts to wind. For now, there still
appears to be a potential for SCA winds (15-20 kt) from either
SE winds Fri or ENE winds this weekend. However, confidence has
decreased. Winds on the 12z models aren`t as high due to high
pressure building in to the NE of the local area Fri, helping
the tropical system curve away from the local area (to the W)
and placing the better pressure gradient SW of the local waters.
Expect forecast changes in the coming days as details regarding
both the cutoff low and PTC 9 become more clear.

Waves and seas this afternoon were generally 1-2 ft (2-3 ft at
the mouth of the bay) and 4-6 ft (6-7 ft across the northern
coastal waters) respectively. Expect seas to remain elevated
through this weekend. As such, have extended SCAs (for seas)
through Wed (with future extensions likely). Additionally, there
will be a brief period where waves at the mouth of the bay may
reach 3-4 ft Tue evening with the brief surge. However,
confidence is too low to issue SCAs with this update.

&&

.TIDES/COASTAL FLOODING...
As of 330 PM EDT Monday...

Key Messages:

- Long duration coastal flood event continues across the region
  (see section below for info on this being a record at a few
  sites).

- Water levels today are expected to be similar to Sunday. At
  least minor flooding is likely to persist through Tuesday,
  possibly into Wednesday in portions of the mid/upper Bay.
  Various headlines remain in effect (see latest CFWAKQ for
  details).

Tidal departures continue to average +1.5 ft to +2.0 ft above
astro tide levels across the region. The high tides this
afternoon into this evening look to reach levels similar to what
occurred Sunday afternoon/evening. Again, the most widespread
moderate flooding (with local major flooding at a few places)
will be over the mid/upper Bay, including the tidal
Potomac/Rappahannock and the MD eastern shore through late this
evening. These locations still are expected to see additional
moderate coastal flooding continue into Tuesday as winds veer to
the E-SE and long period easterly swell remains in place over
the ocean, allowing water trapped in the Bay to shift northward.
As such, Coastal Flood Warnings remain in effect through
Tuesday evening.

Areas to the south across the lower Bay/tidal James and York
rivers will be more marginal, with peak water levels mostly in
the high end minor flood to locally moderate thresholds this
afternoon/evening. However, given that tidal anomalies remain
fairly consistent, the high tide this afternoon/evening should
be comparable to what occurred on Sunday, so will maintain these
Coastal Flood Warnings here through the late afternoon/evening
timeframe. Have mentioned in the CFW the likelihood at seeing
additional flooding Tuesday (most likely minor flooding).

Norfolk and Chesapeake remain in a Coastal Flood Advisory
through Tuesday (as opposed to a Coastal Flood Warning) given
that the Elizabeth River and Sewell`s Point should remain below
moderate flood stage. A Coastal Flood Advisory also remains
across the Atlantic side of the Maryland Eastern Shore with
Ocean City looking to remain in minor flood stage through this
afternoon.


As of 345 AM EDT Monday:

Consecutive high tides reaching at least Minor Flood with this event:

- Lewisetta (P.O.R. since 1979): 13 (with several more to   come),
previous record was 8 in Oct 2021, Oct 2019, Oct 2015.

- Cambridge (P.O.R. since 1980): 7 (with several more to come),
previous record was 5 in Oct 2021, Oct 2019, Sep 2018, Oct  2011.

Consecutive high tides reaching at least Moderate Flood with this
event: (this event is unlikely to break records listed).

- Lewisetta (P.O.R. since 1979): 3 (so far), ***record is 7 in  Oct
2015***

- Cambridge (P.O.R. since 1980): 1 (so far), ***record is 4 in  Oct
2019***

In addition, a High rip current risk is in effect today and Monday.
A High rip current risk will likely continue through at least
Tuesday.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Warning until 2 AM EDT Wednesday for MDZ021>023.
     Coastal Flood Advisory until 4 PM EDT this afternoon for
     MDZ024-025.
NC...Coastal Flood Warning until 4 PM EDT this afternoon for NCZ102.
VA...Coastal Flood Warning until 4 PM EDT this afternoon for VAZ098.
     Coastal Flood Warning until midnight EDT Tuesday night for
     VAZ075-077.
     Coastal Flood Warning until 10 PM EDT Tuesday for VAZ076-078-
     085-521-522.
     Coastal Flood Advisory until 9 PM EDT Tuesday for VAZ083-518-
     520.
     Coastal Flood Warning until 6 PM EDT this evening for VAZ084-
     086-523>525.
     Coastal Flood Warning until 10 PM EDT this evening for VAZ089-
     090-093-096.
     Coastal Flood Advisory until 6 PM EDT Tuesday for VAZ095-097.
     Coastal Flood Warning until 8 PM EDT this evening for VAZ099-
     100.
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ650-652-
     654-656-658.

&&

$$

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