315
FXUS61 KAKQ 152315
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
715 PM EDT Thu Aug 15 2024

.SYNOPSIS...
Tranquil weather conditions and comfortable humidity levels are
expected this evening, as surface high pressure remains in
place over the region. Precipitation chances gradually return to
the region from Friday night through the weekend, as a slow
moving area of low pressure and series of fronts cross the
region.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 305 PM EDT Thursday...

Key Messages:

- Seasonably warm today with highs in the mid/upper 80s under
  a mostly sunny sky.

- Small chance of an isolated shower or storm along the
  immediate coast through late afternoon.

Latest analysis reveals 1020+mb sfc high pressure centered over
the mid-Atlantic region, with a weak surface trough in place
offshore of the northeast coast, extending south over the
Delmarva. To the west, low pressure continues to lift across
the northern plains, with an associated surface cold front
slowly crossing the plains into the middle and upper Missouri
Valley. Aloft, upper troughing is sliding offshore, with upper
ridging building across the region in its place, with W-NW flow
aloft over the region.

A seasonably warm afternoon across the local area. 19z readings
are in the mid to upper 80s, slightly cooler low 80s along the
immediate coast. Light downslope flow is allowing for dewpoints
mixing out and falling back into the mid to upper 50s to low 60s
over inland areas this afternoon. CAMs continue to suggest that
we could see an isolated shower or storm pinned to the
afternoon sea breeze, with the best chance along the surface
trough over the MD/VA eastern shore. However, the PW values AOB
1" and a weak convective cap should keep a lid on convective
chances today outside of a SCT afternoon CU field. Otherwise,
and a stellar August afternoon weather wise. Skies remain
mostly to partly sunny sky, aside from a bit of smoke aloft from
western fires. Highs in the mid to upper 80s with comfortable
humidity levels.

The surface high slides toward the coast tonight, then offshore
into early Friday. Incrementally milder tonight vs last night,
but still expect early morning lows in the low/mid 60s, with a
few upper 50s possible in typically cooler spots out in the
piedmont.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 305 PM EDT Thursday...

Key Messages:

- Seasonably warm and a bit more humid Friday with a slight
  chance of late evening/overnight showers west of I-95.

- Increasing chances for showers/storms though the weekend as a
  series of weak cold fronts pass through.

The flow aloft becomes more quasi-zonal Friday, as the upper
ridge shifts offshore and weakens and low pres dips into the
western Great Lakes region. Meanwhile, TC Ernesto will travel
northward well offshore from the Carolina coast. A weak pre-
frontal trough will likely trigger a few showers/storms Friday
night for the far western counties, but latest guidance cont to
trend drier locally, keeping the bulk of QPF to the west. Will
maintain a slight chance across the western border late Fri
evening and overnight. Highs will be in the mid/upr 80s, and it
will be noticeably more humid as dewpoints rise into the mid
60s.

Rain chances ramp up a bit over the weekend into Monday, as a
series of weak cold fronts push into the area and the parent
upper low slowly approaches from the west. PoPs are mostly dry
for most of the day Saturday, then precip chances increase
(30-50%) in the late afternoon, evening and overnight. Highs on
Sat will once again be in the mid/upr 80s.

Coverage of showers/storms looks to be higher on Sun with as
the parent low and trough axis moves slightly closer to the
area, with better forcing pushing in by afternoon and evening.
PoPs will be up to around 40-50% over the entire area in the
afternoon. There could easily be a few stronger storms as well,
with LREF showing SBCAPE ~1000-1500 J/kg with 25-35 kt of deep
layer shear. Precip will end from W to E Sun night. Highs Sun in
the upper 80s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 305 PM EDT Thursday...

Key Messages:

- Warm and humid on Monday with another chance for afternoon
  thunderstorms.

- Returning to cooler, drier pattern for the midweek period.

Models continue to be a bit more progressive with the sfc trough
early next week, with increasing confidence that a cooler, drier
pattern eventually takes shape for the middle to latter portion
of next week. The upper trough axis crosses the area Monday, and
will serve to kick the lingering surface trough toward the coast
Monday evening. Expect that this likely triggers another round
of some showers/storms in the afternoon, especially east of I-95.
Highs on Mon will be in the mid/upper 80s. NW flow returns Tue-
Thu, as the trough moves offshore and high pressure builds in
from the NW Tue- Wed, with cooler/drier conditions pushing into
the region. Highs will be in the low-mid 80s with lower humidity
levels (Dewpoints in the 50s to low 60s) are now well supported
by model ensemble probabilities. Should be mainly dry, but
cannot rule a a stray shower along the coast in the afternoons.
Early morning lows in the mid to upper 60s Monday night, and in
the mid to upper 50s well inland to mid 60s Wed-Thu mornings.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 715 PM Thursday...

Mainly FEW-SCT250 skies through the period. Could have some
afternoon CU again on Friday. There is some haze due to smoke
aloft. Winds will be light and variable overnight, becoming
south/southwesterly at western terminals during the day and
southeasterly at eastern terminals.

Outlook: A slow moving cold front will approach from the west
late Friday through Sunday with chances for mainly aftn/evening
showers/tstms each day, especially Sunday.

&&

.MARINE...
As of 305 PM EDT Thursday...

Key Messages:

- Quiet conditions continue through early Friday. Elevated
  southerly winds are expected from Friday night through
  Saturday night, potentially bringing marginal SCAs to the
  bay.

- Small Craft Advisories have been issued for the northern
  coastal waters starting Friday evening and are likely for the
  remaining Atlantic waters and mouth of the Chesapeake Bay
  starting on Saturday as swells from Hurricane Ernesto reach
  the coast (see tides/coastal flooding section below.

High pressure over PA will translate slowly toward the coast
tonight. Locally, winds are generally from the N and NE at 5-10 kt
but will become S and SE 5-10 kt this evening and overnight. High
pressure to the north moves offshore tomorrow ahead of low pressure
and cold front over the Midwest. This low/front will be slow to move
east tomorrow into Saturday but the pressure gradient does look to
sharpen enough to result in marginal SCA conditions in the Ches Bay,
especially the middle and upper portions. Meanwhile, Hurricane
Ernesto, currently well E of the Bahamas, is forecast to lift NNE,
tracking near Bermuda by early Sat. Impacts locally will be
restricted to increasing swell and the threat for deadly rip
currents. Opted to raise SCA flags for the Atlantic waters north of
Cape Charles Light starting at 02z/10pm Friday. The remaining
Atlantic waters and mouth of the bay will see seas/waves increase
later on Saturday and additional small craft headlines will be
needed in subsequent forecasts.

Seas peak at 5-7 ft Sunday into Sunday evening. Waves near the mouth
of the bay will increase as well, generally 2-3 ft on Saturday with
3-5 ft possible Sunday before things start to calm down Monday
(though will likely have seas offshore linger at 4-5 ft possibly
into early Tuesday). The models are in decent agreement that another
eastern CONUS upper trough develops next week, allowing a cold front
to move through the local waters Tuesday with winds shifting to the
N/NW.

&&

.TIDES/COASTAL FLOODING...
As of 305 PM EDT Thursday...

Key Message:

-  A Moderate Risk of Rip Currents is forecast for Friday, with
   a High Rip Risk likely for both Saturday and Sunday as long
   period swell from distant Hurricane Ernesto affects the
   region.

The latest 15/12Z run of the NWPS supports high rip risk for
all Atlantic coastal zones by Sat given seas of 4-6 ft with a
dominant period of 13 seconds or greater. Friday is a bit more
uncertain as waves may only be ~2 ft until later in the day so
will continue with a Moderate rip risk for now. Some minor tidal
flooding will be possible (mainly in the mid/upper Bay) by
Sun/Mon as the combination of southerly winds and the potential
for water becoming trapped in the Bay develops with the long
period swell.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 10 PM Friday to 8 PM EDT Sunday for
     ANZ650-652-654.
     Small Craft Advisory from noon Saturday to 8 PM EDT Sunday for
     ANZ656-658.

&&

$$

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