208
FXUS61 KAKQ 180537
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
137 AM EDT Sat May 18 2024

.SYNOPSIS...
Showers become widespread across the piedmont later this
evening, and slowly shift east overnight, remaining likely
through most of Saturday. The widespread rain will shift south
later Saturday night into Sunday, though at least light rain or
drizzle will still be possible. Dry weather returns Monday,
with a warming trend leading to a more summerlike pattern by the
middle of the week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 955 PM EDT Friday...

Key Messages:

- Rain becomes more widespread late tonight and overnight, from
  W to E (reaching the coast between 06-12Z). Locally heavy
  rainfall is possible (mainly west). A Flood Watch is in place
  over portions of the Piedmont.

- Showers continue Saturday with below normal high temperatures,
  additional heavy rain possible.

Latest analysis continues to show 1020+mb Sfc high pressure
centered across Atlantic Canada into northern New England,
ridging into the northern mid-Atlantic. A weak quasi-stationary
boundary remains draped from NW to SE across south central VA
into north central and eastern NC. 00z PW values have increased
to 1.5 to 1.7" over the southern third of the area in advance of
a southern stream shortwave lifting out of the mid-south late
this evening into the overnight.

Showers are becoming more widespread across the piedmont, and
will push east to the I-95 corridor in the next few hours,
reaching the coast late tonight. PWs increase to 1.6-1.8"
overnight. T-storm potential is minimal and should be confined
mainly W of I-95 and along and S of route 460 through 06-087z or
so, removed from the cooler/less stable marine airmass closer
to the coast. Relatively mild tonight with lows around 60F,
except in the low- mid 50s on the eastern shore. Have added
Mecklenburg County VA to the Flood Watch, which remains in
effect for much of our piedmont counties W-SW of RIC metro.

00z CAMs are trending towards higher coverage and QPF remaining
across these areas in the piedmont just ahead of the boundary
overnight. This matches the 12z/17 HREF PoPs and probability
matched mean QPF fields. Locally heavy rainfall is likely in
spots. WPC has a slight ERO just NW of our wrn CWA line, with a
marginal across our W/NW counties. As the boundary slowly lifts
E-NE early Saturday, the axis of heavier rain looks to also
slowly shift eastward near and after sunrise Saturday, with some
signal for heavy rainfall also across srn portions of the area
with some elevated instability also sliding through.

Weak sfc low pressure tracks just S of the area Sat afternoon.
While moist WSW flow aloft and deep lift continues over the
region in advance of the approaching upper-level system,
coverage of rainfall may be hit or miss later Saturday morning
into early/mid aftn as earlier day rain/convection limits any
aftn destabilization. Current thinking is most of the heavier
showers and storms stay to our W or SW, though cannot rule out a
few storms clipping our SW counties. High temps Sat will remain
below normal w/ the onshore flow and are in the 60s N to low
70s over the far south. The vast majority of the QPF falls
tonight through Saturday and totals of 0.25-0.50" are expected
on the eastern shore, 0.50-1.00" over most of the rest of the
CWA, with 1.00-1.50" (local amounts in excess of 2.00" possible)
in the piedmont. The Flood watch remains in effect for portions
of the VA Piedmont. Some heavy rainfall and 1-2" is possible
over areas w/ low 3- and 6-hr flash flood guidance (where 3-5"
of rain fell earlier this week). Did not expand the Watch given
a general downward trend in QPF and with a lot of uncertainty/spread
in the HREF means. For instance, in areas with a median amount
of 1.00-1.50" the 25th percentile has less than 0.75".

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
As of 330 PM EDT Friday...

Key Message:

- The more widespread rain and any additional heavy rain threat
  shifts S of the area after Sat evening.

- Dreary weather and a chc for additional showers are expected
  Sunday across the south, with drier WX later over the north.
  High temperatures will remain below normal.

the 12Z/17 models generally show high pressure to north slowly
building south Sat night through Sunday, as sfc low pressure
moves east across the Carolinas. Still enough upper level
support for likely PoPs south and chc PoPs elsewhere Sat night,
with some additional moderate to locally heavy rainfall possible
over far southern VA and NE NC. By Sunday, PWATs drop off to
<1.50" even in the south, with only the far southern areas expected
to see 0.10" or more of additional QPF. Total QPF for this
system will average 0.50"-1.00" over much of the CWA, with
1.00-1.50" and locally higher amounts possible in the piedmont
and over extreme SE VA and NE NC (as some additional higher QPF
affects SE VA/NE NC into Sat night).


Sunday PoPs have been lowered to 40-50% in NC, and to 15-30%
elsewhere. Note that even with this continued trend to a drier
solution for Sunday, it will still be relatively unpleasant with
increasing NE winds, cloudy skies, and highs only in the 60s.
There could be some partial clearing over the northern 1/2 of
the CWA Sun aftn so highs may reach to around 70F. Partly cloudy
NW to mostly cloudy SE Sun night with lows in the 50s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 350 PM EDT Friday...

Key Messages:

- Temperatures remain below normal Monday with mostly cloudy
  skies along the coast.

- Dry/sensible weather expected Tuesday and Wednesday with
  temperatures trending much warmer. A chance for aftn storms
  Thu.

Low pressure gradually shifts offshore Monday, though an additional
low may develop S of the upper feature offshore. High pressure also
nudges south into the Mid-Atlantic. NE flow is still expected
(breeziest across southern coastal areas), keeping temperatures
below normal across the SE, and slight below normal elsewhere.
The low levels dry out enough well inland, allowing
temperatures to warm into the mid 70s. Upper 60s are expected
along the coast. The majority of the area stays dry with just a
slight chc of shower along the SE coast. Lows Mon night in the
50s with some upper 40s possible well inland.

Stacked sfc and upper low now gets pushed offshore rather
quickly Mon night, with upper level ridging moving in by Tue. As
such, have trended the forecast warmer for Tue/Wed, with highs
Tue now in the upper 70s/lower 80s inland and in the low-mid
70s at the coast. The warming trend continues Wed into Thu with
mid/upper 80s making a comeback. There is decent agreement among
the global models that a cold front will cross the area later
Thursday afternoon. Will have a chc of showers and storms over
most of the area. A little cooler behind the front to end the
week. Overnight lows will be in the 50s Tue night and 60s for
the remainder of the week.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
As of 135 AM EDT Saturday...

There are two areas of low clouds this morning. The first is a
widespread area of 600-1000 ft CIGS, mainly W of I-95 and RIC
(associated w/ a large shield of rain). There are also patchy
MVFR CIGs closer the coast associated w/ a maritime airmass and
NE onshore flow. For ORF, PHF, SBY, and ECG, cannot rule out
SCT- BKN MVFR CIGs, but prevailing VFR is forecast for at least
next few hrs. RIC will drop to IFR first this morning, around
10z (cannot rule out a hr or so earlier). Degraded flight
conditions and rain showers then push E to the remainder of the
terminals by mid-late morning w/ initially MVFR CIGs and then
IFR by the aftn today (SBY may stay MVFR for most of today).
Coverage of showers may lower some later in the aftn, but IFR
CIGs and potentially some drizzle will keep flying conditions
less than ideal. There is also a chc of LIFR CIGs, but
confidence is not high enough to include in the TAFs at this
point. Degraded VSBY in rain/drizzle also likely. E-NE winds
are light this morning, with 5-10 kt winds prevailing for the
remainder of the period.

Outlook: At least some chance for showers (and flight
restrictions likely) into Sunday morning, with the best chance
at srn terminals. Mainly dry by Sun afternoon and night with a
few lingering showers in the SE. Dry Mon-Tue.

&&

.MARINE...
As of 200 PM EDT Friday...

Key Messages:

- Sub SCA conditions expected this evening and overnight.

- Increasing NE wind and waves for the weekend. Small craft
  advisory conditions are expected over the entire marine area
  later Saturday and through SUnday. Wind gusts to 20 to 25 kt
  and seas building to 4 to 7 feet.

Weak high pressure is centered along the coast from the
Carolinas to New England. The wind was generally NE at or below
15kt this afternoon, with seas 3-4ft and waves in the Bay
mainly 1-2ft. An area of weak low pressure will slowly
approach from the west Saturday as high pressure remains over
New England resulting in a tightening pressure gradient late Sat
into Sun. The wind will remain NE overnight tonight around
5-10kt, becoming E to SE 5-10 kt by morning. E winds increase to
10-15kt through the morning hours with 15 kt potentially
gusting to 20 kt mid to late Saturday afternoon. Seas will
mainly be 3-4ft tonight into Saturday then build late Saturday
into Sunday.

Low pressure becomes more organized off the Carolina coast Saturday
night into Sunday, before very slowly pulling away from the coast
through Monday. Meanwhile, high pressure slowly builds in from the
N. A NE wind is expected to range from 15-20kt with gusts to 25
kt (strongest for the lower Bay and ocean) with seas building
to 4-5ft N and 5-6ft S and 3- 5ft waves in the mouth of the Bay.
SCAs are likely during this time period for the lower
Bay/ocean, with less confidence of SCA conditions elsewhere.
High pressure builds across the Mid-Atlantic coast Tuesday into
Wednesday as weak low pressure lingers off the Southeast coast.

&&

.HYDROLOGY...
As of 320 PM EDT Friday...

Flood Warnings remain in effect for Nottoway River near Stony
Creek for minor flooding. Lawrenceville crested last night and
has now fallen below flood stage. Stony Creek remains in flood
and is expected to crest tonight. See FLSAKQ for additional
information.

While uncertainty remains with respect to rainfall amounts and
exact placement over the weekend, median expected amounts are 1.00-1.50"
range across area basins over the weekend. Latest forecasts
indicate these amounts will lead to a secondary rise in water
level late in the weekend/early next week, but that most places
stay just below Minor Flood thresholds, though will need to
monitor as a slight over-performance would lead to additional
flooding.

&&

.TIDES/COASTAL FLOODING...
A Coastal Flood Advisory is in effect for the upper Bay and
portions of the Northern Neck for the high tide this evening.
Two strong flood tides with very weak ebbing is resulting in a
piling up of water from Windmill Point north. Minor tidal
flooding is likely at Lewisetta and Bishops Head this evening.
Water levels should drop with stronger ebbing expected overnight
before the Saturday morning high tide.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Advisory until 2 AM EDT early this morning for
     MDZ021.
NC...None.
VA...Coastal Flood Advisory until 2 AM EDT early this morning for
     VAZ075-077.
     Flood Watch until 10 AM EDT this morning for VAZ048-060-061-
     065>068-509.
MARINE...None.

&&

$$

SYNOPSIS...LKB
NEAR TERM...LKB/MAM
SHORT TERM...LKB/SW
LONG TERM...LKB/SW
AVIATION...MAM/SW
MARINE...AJZ/JAO
HYDROLOGY...
TIDES/COASTAL FLOODING...