277
FXUS61 KAKQ 031939
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
339 PM EDT Fri May 3 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 SATURDAY/...
As of 330 PM EDT Friday...

Key Messages:

- Dropping temperatures expected this afternoon behind a backdoor
cold front.

- On and off showers expected tonight through Saturday with the
highest coverage inland.

- Becoming dreary for all areas Saturday with extensive low-level
cloud cover.

Sfc obs, satellite, and radar data show the backdoor cold front
quickly marching W/SW across the area. Behind the front, temps are
falling quickly. It`s in the 50s on the VA/MD Eastern Shore and in
the 60s across Hampton Roads northwards to the Northern Neck. Ahead
of the front (over the Piedmont), temps have risen into the mid and
upper 80s. Thus, we are currently seeing a very impressive
temperature gradient over the area (55 at Ocean City/OXB vs 87 at
South Hill/AVC). Extensive low-level clouds are also slowly pushing
inland from the ocean and Chesapeake Bay. Expect the front to
continue advancing westward for the remainder of this afternoon. A
few CAMs show a few pop-up showers or storms developing along the
front given building instability (SPC mesoanalysis showing ~500-1000
J/kg across the Piedmont). Will continue a 20% PoP for these areas
through the afternoon. Additional shower chances are expected
overnight, with the highest coverage expected over the nrn half of
the area. Not expecting any thunder tonight. Some patchy fog may
also move onshore across SE VA and NE NC, but think visibilities
will not get too low given the elevated winds. Lows tonight will be
chillier than the previous few nights and around 50 on the MD
Eastern Shore to the mid-upper 50s for the rest of the area (lower
60s down along the Albemarle Sound).

The front will be well W/SW of the area by tonight into Saturday.
Sfc high pressure will be left in its wake across New England. This
will wedge a cool/moist low-level airmass over the entire area for
the day Saturday. This will also keep cloudy conditions in place.
The best forcing/lift and moisture remains across the W, so
expecting the highest coverage Saturday mainly W of I-95. Despite
this, it will tend to remain unpleasant even towards the coast w/
onshore flow and patchy drizzle. Continue to trend highs lower with
temps struggling to reach 60 across the N, with mid 60s-low 70s
elsewhere. There is a chance that far SW portions of the CWA (e.g.,
Northampton/Bertie Counties in NC) reach the upper 70s, but this may
even be overdone. These values are still below NBM (especially S).
On and off "showery" rainfall continues overnight Saturday with lows
in the 50s N to 60s S. QPF through tomorrow averages from up to
0.50" across the W, 0.1-0.4" central, and 0.00" to a few hundredths
of an inch closer to the coast.

&&

.SHORT TERM /SATURDAY NIGHT 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 /19Z FRIDAY THROUGH WEDNESDAY/...
As of 215 PM Friday...

Degraded flight conditions are expected through most of the
03/18z TAF period as a backdoor cold front pushes further inland.
As of 18z, IFR CIGs (bases ~800 ft) have moved into ORF and
PHF. MVFR CIGs are noted at SBY, with VFR at RIC. Expect these
IFR CIGs to persist along the coast through the period.
Elsewhere, expect SBY and ECG to drop to IFR CIGs over the next
few hrs, with RIC holding off until this evening. CIGs may then
drop further to LIFR for a time tonight (best chances at ORF
and ECG). Additionally, there may be VSBY reductions below 3 SM
due to BR or FG. This part of the forecast is more uncertain so
have not gone lower than 3 SM in the TAFs at this time. In terms
of precipitation, most stay dry this aftn (a very brief shower
or storm cannot be ruled out at RIC), before more widespread
shower activity approaches the W later tonight into Saturday.
Areas of drizzle are also possible. Winds have turned to the E
behind the front at all TAF sites and E winds 10 should avg ~10
kt overnight into Saturday.

Outlook...Sub-VFR conditions expected at times through through
the weekend and even into early next week due to an unsettled
weather pattern. A warmer, more summerlike pattern returns by
Tuesday with chances for storms each afternoon/evening.

&&

.MARINE...
As of 300 PM EDT Friday...

Key Messages:

- Small craft advisories are in effect for the Chesapeake Bay
  and lower James River. Advisories were expanded south to the
  NC/VA border and extended through this evening.

- Winds of 15 to 25 kt will persist this evening then diminish
  a bit late tonight/Sat morning, but winds may increase some
  Saturday and additional Small Craft Advisories may bee needed
  by Saturday/Saturday night.

Winds increased abruptly as expected earlier today behind the
backdoor cold front. Overall the NE winds have over-performed
with some gusts of 25 to 30 kt at times over the ocean and lower
Bay. SCA advisories are in effect for the Bay, lower James River
and coastal waters from the NC/VA border north. Winds will
persist into this evening, but should slowly decrease some by
midnight. That said given the pattern and gradient winds will
remain E-ENE at 15 kt gusts to 20 kt through the overnight.
Seas have increased to 4 to 6 ft from Cape Charles north and 3
to 4 near the NC/VA border. Given the easterly flow seas over
the ocean and waves at the mouth of the Bay may be slow to
decrease overnight.

Wind speeds increase again later Sat aftn/Sat night while
shifting to the SE and this reflected by nearly all of the
guidance. This brings another chance at SCA conditions, again
mainly over the Bay. Seas remain 3-4 ft with waves 2-3 ft in the
bay/rivers/sound.

The front lifts back N on Sunday, shifting winds to the S. 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 300 PM EDT Friday...

Have issues a Coastal Flood Statement for locations in the upper
Bay as tides increase and approach minor flood levels later on
Saturday. Tidal departures will increase overnight due to winds
persisting onshore from the E or ENE. Moderate levels are not
expected (except perhaps locally at Bishops Head), so no Coastal
Flood Watches are anticipated.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 1 AM EDT Saturday for ANZ630>632-
     634-638.
     Small Craft Advisory until 7 PM EDT this evening for ANZ650-
     652-654-656.

&&

$$

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