359
FXUS61 KAKQ 040713
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
313 AM EDT Sat May 4 2024

.SYNOPSIS...
A backdoor cold front pushes south and west of the area tonight.
On and off shower chances are expected Saturday and Sunday. Summerlike
conditions return to the area for next week with daily chances
of showers and storms.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 310 AM EDT Saturday...

Key Messages:

-Dreary conditions across the entire forecast area today with
 extensive low-level cloud cover and scattered showers.

Yesterday`s backdoor cold front is situated just south of the FA
early this morning. High pressure over New England is wedging cool,
moist air into the Mid-Atlantic. With the front projected to stay S
of the area today, expect a dreary Saturday. Latest radar shows
scattered showers, primarily W of I-95. Chances for showers will
continue through the day, but with the best forcing/lift and
moisture remaining to the W, the highest coverage will continue to
be over the piedmont. Closer to the coast, low level moisture from
onshore flow will allow for patchy drizzle to continue through the
morning.  Minimal thunder is expected today, but could have a
few rumbles in SW counties this evening. Easterly winds will be breezy
E of I-95, especially near the coast, with gusts of 15-25mph.
Temps today will be cool across far northern portions of the
FA. Highs will struggle to even reach 60F. Far southern portions
will likely see a few breaks in the clouds and winds will have
a slight southerly component, allowing for warmer temps in the
mid 70s. The gradient between these warmer temps and the rest of
the FA will likely be sharp, so expect most will see cooler
highs in the 60s.

Showers in the far western counties increase in coverage overnight
with lower end chances extending E to the coast. The front will
start to move back N overnight, leading to stable if not slightly
increasing temps late tonight/early Sunday. Lows will be in the low-
mid 50s across the N and low 60s in the S.

&&

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

Key Messages:

- Continued unsettled, but warmer, Sunday.

- More humid on Monday with showers and storms areawide.

The front is expected to lift back N Sunday into Monday, shifting
the low-level flow to the S. These factors should act to scour out
the dreary conditions seen on Saturday. However, still expecting
shower redevelopment in the aftn hours as temps warm into the 70s
and 80s and the residual front and a weak disturbance aloft remains
near the area. An early look at some CAMs show that they are not
particularly enthusiastic at widespread rainfall coverage, which
makes sense given a lack of any focused areas of lift. Lows Sun
night in the 60s.

Upper heights begin building back N for Monday with high temps
warming into the low 80s areawide. Despite the warmer temps, a lee
trough is expected to develop in the aftn and evening hours.
Combined w/ an approaching shortwave from the OH River Valley,
showers and storms are expected to develop over the higher terrain
in the afternoon and slide eastward into the evening. Models show
around 1000 J/kg of CAPE developing with rather weak shear.
Therefore, the severe threat looks relatively low, but cannot rule
out a stronger storm or two. Soundings do show a rather saturated
atmospheric column (PWATS potentially reach or exceed 1.5"), which
could lead to some heavier downpours. Dew points also increase into
the mid-upper 60s so the humidity will make it feel more like early
summer. Shower/storm activity diminishes inland after midnight, but
may linger closer to the coast overnight. Lows remain mild in the
mid 60s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 335 PM EDT Friday...

Key Messages...

- A more summer-like pattern with warmer days and chances for
  late afternoon and evening showers and storms appears to be on
  the way for the middle to end of next week.

We get into an almost summertime pattern by Tuesday as the ridge
aloft builds overhead with afternoon/evening showers and
thunderstorms each day being triggered by the lee side trough. The
GFS and ECMWF both suggest the ridge breaks down slightly by Wed/Thu
with stronger 500mb flow of up to 50 kt by Wed afternoon. Along with
this, those models suggest weak shortwaves (likely of mesoscale
origin from convection over the Ohio Valley and central plains)
moving through the area. These convective complexes may also move
through the region from the NW, but these features are
notoriously hard to predict. Although we are talking about days
5-7, the relatively strong upper flow combined with relative
steep mid level lapse rates of up to 7-7.5 C/km would suggest
the possibility of severe weather. Instability will certainly
not be a limiting factor as temps warm into the 80s and 90s
every day. At this time, the synoptic pattern for severe looks
most favorable Thursday with an approaching trough and the most
robust CAPE. The CSU Machine Learning Probabilities have picked
up on the aforementioned parameter space and suggest at least a
slight risk for severe weather on Wednesday and Thursday for
the entire area and Friday for southern/southeast areas. We
continue to have plenty of time to monitor this, but the area
may become more active by the end of next week.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
As of 145 AM EDT Saturday...

Degraded flight conditions are expected to continue through the
06z/04 TAF period as IFR to LIFR CIGs have already overspread
the terminals in the wake of a backdoor cold front (with E-NE
winds of 10-15 kt with gusts to 20 kt). IFR/LIFR CIGs are
expected through much of the night with perhaps some
improvement on Sat (to 1000-2000 ft) with continued onshore
flow. In terms of precipitation, scattered showers have spread
over western portions of the area, and Richmond will likely see
brief periods of light rain. Areas of drizzle are also possible
through Sat AM. Shower chances continue on Saturday (highest
PoPs at RIC w/ lesser chances near the coast).

Outlook...Sub-VFR conditions expected at times through the
weekend and even into Monday due to an unsettled weather
pattern. Scattered showers and tstms are expected on both Sunday
and Monday. A warmer, more summerlike pattern returns by
Tuesday with chances for storms each afternoon/evening.

&&

.MARINE...
As of 710 PM EDT Friday...

Key Messages:

- Small Craft Advisories have been extended for the Chesapeake
  Bay and lower James River through Saturday night.

- Small Craft Advisories for the seas north of the
  Virginia/North Carolina border have been extended until 1 AM
  Saturday.

- Winds of 15 to 20 kt with gusts to 25 kt will diminish a bit
  later tonight into Saturday morning before increasing
  Saturday.

Winds behind the backdoor cold front remain 15-20 kt with gusts
to 25 kt this evening (lower across the NC coastal waters).
Winds diminish some overnight but should still gust to 20 kt
through the night. Winds ramp back up Sat afternoon into Sat
night with gusts to 25 kt. Winds become ESE late Sat night as
a warm front lifts N. Waves remain 2-4 ft during this time.
Given the gusts to 20 kt between the two surges, have opted to
extend SCAs through Sat night to account for both surges for
the Ches Bay and Lower James. Additionally, with seas of 4-6 ft
this evening N of the VA/NC border and persistent E flow, seas
should be slow to subside to 4 ft tonight. As such, have
extended SCAs for all coastal waters N of the VA/NC border until
1 AM Sat.

The front lifts back N on Sunday, shifting winds to the SE/SSE.
SSW winds return for Monday through the middle of next week
(but likely remain sub-SCA).Southerly flow looks as though it
will persist through most of next week with the next backdoor
cold front possible some time Friday.

&&

.TIDES/COASTAL FLOODING...
As of 905 PM EDT Friday...

Have maintained a Coastal Flood Statement for locations in the
upper Bay as tides increase and stay just shy of minor flood
stage overnight. Tidal anomalies continue to increase this
weekend with minor to locally moderate flooding (at Bishops
Head) possible across the middle and upper bay due prolonged
onshore flow. Nuisance to minor flooding is possible up the
James River as well Sat evening. Will likely need to upgrade the
Coastal Flood Statement to a Coastal Flood Advisory across
parts of the upper Bay for the Sat afternoon high tide. However,
given that the upcoming high tide stays just below, will hold
off for now.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 7 AM EDT Sunday for ANZ630>632-634.
     Small Craft Advisory until 4 AM EDT Sunday for ANZ638.
     Small Craft Advisory until 4 AM EDT early this morning for
     ANZ650-652-654-656.

&&

$$

SYNOPSIS...SW
NEAR TERM...AM
SHORT TERM...SW
LONG TERM...AM/SW
AVIATION...AM/ERI
MARINE...LKB/RMM/JAO
TIDES/COASTAL FLOODING...