460
FXUS61 KAKQ 210716
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
316 AM EDT Sat Sep 21 2024

.SYNOPSIS...
High pressure looks to linger across the Southeast with a series of
shortwaves passing through our area ahead of a developing area of
low pressure. Off and on rain chances will persist through the
forecast period. Cooler temperatures are expected to start next
week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 315 AM EDT Saturday...

Key Messages:

- Pleasant weather for most of the day 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.

Fairly quiet this morning with high pressure centered well to
the N ridging down the East Coast and low pressure still well
offshore to the NE. Aloft, a trough axis is located offshore,
and a broad ridge is situated to the west which places the local
area under NW flow. Similar to last night, obs are showing some
patchy fog. So far, dense fog has been isolated/brief, and this
should remain the case through the rest of the early morning
hours. Temps are running a bit cooler than forecast for much of
the area. Clouds over the piedmont are keeping temps in the mid
60s, but to the E, under clear skies and calm winds, temps have
already dropped in to the upper 50s in some of the cooler spots.


Today should be pleasant as precip will hold off until the late
afternoon hours. A shortwave traveling down the ridge will trigger
showers and perhaps a few rumbles of thunder late today. CAMs are in
pretty good agreement regarding timing and coverage of precip. May
see a shower or two enter the far NW counties in the second half of
the afternoon, but majority of precip should move in after sunset.
Scattered showers/storms then gradually cross the area overnight.
Will note that SPC has included far western portions of the area in
a MGNL for today. There will be decent shear in the area, as the 00z
HREF shows ~30-35kt of effective shear. However, the window for
severe weather will be limited given the narrow timeframe for
sufficient CAPE. If severe storms do form, the threats would be
damaging wind gusts and hail. Highs today will be in the low 80s for
most, and the mid-upper 70s immediately near the coast. Lows tonight
will be in the mid-60s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
As of 245 PM EDT Friday...

Key Messages:

- Showers and storms expected Saturday evening into the overnight
hours.

- Becoming mostly dry and cooler to start the new week.

The ridge of high pressure will move a bit eastward along the Gulf
Coast this weekend while weakening. Shortwaves will ride along the
northern edge of the ridge into our neck of the woods. The first is
expected to move in later Saturday afternoon with increasing rain
and storm chances. Hi-res model guidance continues to keep the best
chances of rain/storms along and west of I-95 Saturday evening into
the early overnight hours. The Storm Prediction Center does have our
northwest CWA corner in a Marginal Risk for severe weather on
Saturday. The primary threat would be localized gusty winds,
especially where more daytime heating occurs and the storms move in
first. The HRRR tries to have a second round of activity move down
from the north during the early morning hours of Sunday and affect
areas east of I-95, but the NAM Nest and RAP aren`t as excited about
it. Did include a slight chance of rain for coastal locations
before sunrise on Sunday. Kept PoPs low for Sunday evening
aside from isolated showers across NE NC as we should
temporarily dry out.

Moisture lingers along the top of the ridge ahead of another
shortwave on Monday. The shortwave doesn`t move much through the
day, so any rain chances will likely be focused across the far
western edge of the CWA. High temperatures will be in the lower 80s
on Saturday, then cooling into the mid 70s by Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 245 PM EDT Friday...

Key Messages:

- Low-end precipitation chances linger.

The area of high pressure looks to be traversing the far southeast
coast on Tuesday before sliding just offshore midweek. An initial
shortwave will cross the middle Mississippi River valley on Tuesday
before ejecting into the Great Lakes ahead of a developing cut-off
low further west. Here locally, we will be in southwesterly flow in
between the high pressure and low pressure, allowing moisture to
continue to slide in around the edge of the ridge. Rain chances
will try to nudge back in on Tuesday, but may get held up to
the western corner of the CWA depending on the position of the
high. Beyond that, models disagree on the position of the broad
area of low pressure, thus confidence in the forecast for
midweek and after is low. Generally, would expect low-end rain
chances to persist for now. Temperatures will gradually warm a
bit as thicknesses rise with the ridge pushing up the coastline.
Highs are forecast to be in the upper 70s to around 80 degrees.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
As of 155 AM EDT Saturday...

Generally VFR to start the 06z TAF period. Patchy fog is
expected this morning and may impact terminals with MVFR and
brief IFR vsbys. Fog will clear up after shortly sunrise.
Expecting dry weather for most of the day. Scattered showers
move in from the NW during the late afternoon hours. Have
introduced VCSH to the RIC and SBY TAFs. Not as confident about
precip impacting the SE terminals within the 06z TAF period, but
cannot rule out a shower toward the end of the period. Light
southerly winds expected at RIC today. NE winds at the coast
gradually become E/SE this evening.

Outlook: Lower CIGs (mostly MVFR) will be likely in most areas
Sun into Sun evening, due to more moist NE or E flow. Isolated
showers will be possible also.

&&

.MARINE...
As of 340 PM EDT Friday...

Key Messages:

- Small Craft Advisories remain in effect for all coastal waters through
  Sunday night.

- Confidence in potential Small Craft Advisory conditions across
  the Chesapeake Bay/lower James River Sunday has decreased.

- Winds increase Sunday with persistent long period swells
  keeping seas elevated into the middle of next week.

Sfc low pressure (~1003mb) lingers well off the NJ coast, with high
pressure centered across NewFoundland/Labrador. The stronger
pressure gradient remains offshore this afternoon, with NE winds
remaining around 10-15 kt with gusts up to 20 kt across the
coastal waters through tonight. Winds become variable 5-10 kt
Sat morning into Sat afternoon before becoming SE 10-15 kt Sat
evening. Cannot rule out a few gusts up to 20 kt across the
upper bay and rivers Sat evening, however, confidence is low.
The low off the Mid Atlantic coast gradually moves south Sun
into early next week. However, models continue to trend lower
with respect to NE winds Sun. There is still a decent surge of
NE winds expected on Sunday, but winds have trended towards 15
kt with occasional gusts up to 20 kt across the lower bay as
opposed to sustained 15-20 kt. As such, confidence is too low
for any headlines (outside of 3-4 ft waves at the mouth of the
bay) for the Ches Bay at the moment. A slow improvement is
expected by mid week, though SCAs for seas are still probable
into at least early Wed given the long period easterly swell.

Waves and seas were 1-2 ft (2-3 ft at the mouth of the bay) and 4-6
ft respectively this afternoon. Seas build to 5-7 ft by Mon before
subsiding by mid week. As such SCAs are now in effect for the
coastal waters this afternoon through Sun night. However, there may
be a period Sat night into early Sun morning where seas drop below 5
ft across the southern coastal waters. That being said, it appears
to be brief lull with seas building later Sun.

&&

.TIDES/COASTAL FLOODING...
As of 340 PM EDT Friday...

Tidal departures are fairly uniform across the entire area,
generally from +1.0 to +1.5 ft above astro tide levels. With rather
high astro tides given the full moon cycle as well as the typical
higher autumn tides, these departures have been enough to lead to
widespread minor flooding over the past few days. Over the next 24-
48 hrs, the onshore flow will persist with sfc low pressure
lingering well offshore and high pressure over eastern Canada nosing
a bit to the south into the weekend. Indications are for tidal
departures to increase into the +1.5 to up to +2.0 ft range by later
Saturday through Sunday (potentially continuing through the middle
of next week). Confidence has increased in reaching near or into
moderate flood stage across the Chesapeake Bay, Virginia Beach,
Currituck, and Accomack/Northampton for at least the high tide Sun
afternoon (potentially several high tide cycles in spots). As such,
have expanded the Coastal Flood Watch to included all of these areas.

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

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Warning until midnight EDT Sunday night for
     MDZ021>023.
     Coastal Flood Advisory until 4 PM EDT Sunday for MDZ024-025.
NC...Coastal Flood Advisory until 6 AM EDT early this morning for
     NCZ102.
     Coastal Flood Watch from 8 AM EDT this morning through Sunday
     afternoon for NCZ102.
VA...Coastal Flood Warning until midnight EDT Sunday night for
     VAZ075-077.
     Coastal Flood Advisory until 6 AM EDT early this morning for
     VAZ098.
     Coastal Flood Watch from 8 AM EDT this morning through Sunday
     afternoon for VAZ098.
     Coastal Flood Warning until 8 PM EDT Sunday for VAZ076-078-085-
     099-100-521-522.
     Coastal Flood Advisory until 6 PM EDT this evening for VAZ083-
     084-086-089-090-093-095>097-518-520-523>525.
     Coastal Flood Watch from Sunday morning through Sunday
     afternoon for VAZ084-086-523>525.
     Coastal Flood Watch from Sunday morning through Sunday evening
     for VAZ089-090-093-095>097.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ650-652-654-
     656-658.

&&

$$

SYNOPSIS...JKP
NEAR TERM...AM
SHORT TERM...JKP
LONG TERM...JKP
AVIATION...AM
MARINE...RHR/RMM
TIDES/COASTAL FLOODING...