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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 151721
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
121 PM EDT Mon Apr 15 2024

.SYNOPSIS...
A cold front drops south through the area this afternoon and
evening with showers and thunderstorms possible for most of the
area. This front is forecast to lift back north as a warm front
Tuesday into Tuesday night. Another front crosses the area
Thursday with a stronger cold front then expected by the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1240 PM EDT Monday...

Key Messages:

1. Warm and dry through early this afternoon.

2. Strong to severe thunderstorms are expected to develop later this
afternoon, spreading southeast into this evening. Large hail and
damaging winds are the main threats.

Forecast is largely on track this afternoon with minor changes
to temps and dew points to match surface observations. Temps
have risen into the low/mid 80s for most of the area under
mostly clear skies.

Attention then turns towards the severe wx threat this
afternoon. A southward-dropping frontal boundary with likely
provide enough sfc convergence to allow for the development of
scattered thunderstorms after about 3-5 PM. Low level moisture
is slowly increasing across the region. Observed soundings from
this morning to our N and NW sampled the Elevated Mixed Layer
(EML) quite well with mid level lapse rates generally 7.5-8.5
C/km. These steep lapse rates, combined with sfc temps well
into the 80s and dew points in the 50s, will allow for 1000-1500
J/kg of MLCAPE by this aftn. Storm organization will also be
fostered by unidirectional WNW/NW flow aloft which leads to
around 30-35 kt of bulk shear. While the WSW sfc flow likely
leads to some mixing and drying during peak heating (and thus
introduces some questions regarding storm coverage), still
expecting at least scattered tstm coverage given the favorable
low-level environment for cold pool propagation and upscale
growth. Coverage may be limited initially as there is also a
small cap shown in soundings that will need to be overcome.

The primary threats are large hail and especially damaging
winds. Hail is expected to favored initially as single cell or
transient supercell structures develop with the support of the
aforementioned mid-level lapse rates. Hail in the 1-1.75" range
is most likely in any discrete severe storm. As additional
storms develop, upscale growth into clusters and/or a line is
expected as storms take advantage of the favorable inverted-V
low-level environment (DCAPE > 1000 J/kg seen in model
soundings). This will then favor the damaging wind threat
becoming dominant. Damaging wind gusts of 60-75 mph are possible
in any storm. The tornado threat remains very low. SPC has
introduced an Enhanced Risk (level 3 of 5) this afternoon,
driven by the potential for damaging straight line winds. The
Enhanced Risk is centered over the north central portion of
area, generally over the Richmond Metro and extending west to
near Farmville, south to the 460 corridor, and eastward along
the western shore of the bay. A Slight Risk (level 2 of 5)
covers the remainder of the area. Will continue to highlight
this threat in the HWO. The highest PoPs and storm coverage are
initially expected N and NE of metro Richmond, spreading S and
SE into the US-460 corridor, Middle Peninsula, and Hampton
Roads. As heating is lost after sunset, storm intensity and
coverage will tend to decrease, especially S of the NC/VA
border. Expect all storms to dissipate by 12-2 AM tonight with
just a lingering shower or two possible. Lows tonight will range
from the mid 50s N to around 60 S.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 325 AM EDT Monday...

The front moves back N as a warm front Tuesday into Tuesday
night as low pressure develops and moves NE out of the Plains
states. The coverage of showers and storms is expected to be
less Tuesday and mainly confined S and W of I-64 initially. The
storm threat is highly dependent on how much instability can
creep N, with the HRRR being the most aggressive with this. Will
have 20-30% PoPs with similar chances of thunder across our SW
counties. Highs Tue range from the upper 60s-low 70s E/NE to
mid/upper 70s-low 80s further W/SW. Low-end chances for a shower
or two continue into Tuesday night with lows in the 50s.

Mostly cloudy skies expected Wednesday with the front remaining near
the area. This could spark additional showers and isolated tstms,
especially N. Highs Wed in the upper 70s-low 80s for most of VA and
NC. It`ll remain around 70 on the Eastern Shore where the flow will
be off the cooler waters. A weak cold front approaches from the W
Wed night/early Thu which leads to a somewhat higher coverage of
showers. PoPs are 30-50% though QPF should remain on the light side
(0.25" or less). Overnight lows Wed in the 50s N/NE and 60s S.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 325 AM EDT Monday...

Remaining on the mild side heading into the extended period with on
and off unsettled periods. Thursday continues to look like the
warmest day of the extended period with highs in the 80s for most of
the area (70s across the NE), despite the weak cold front moving
through. Will keep chance PoPs through the day simply due to the
cold frontal passage occuring during the day. Will also have a low-
end thunder potential across the SE half of the area in the aftn.
Another (stronger) cold front moves toward the area later Friday
into Saturday with additional chances for showers and possibly
thunderstorms. The 00z suite of deterministic guidance is in
somewhat better agreement with the timing of the FROPA. The GFS and
ECMWF both show a Saturday FROPA, though the GFS is still several
hrs faster. Whether this occurs in the morning or aftn dictates the
extend of the tstm threat. There still isn`t much of a high QPF
signal as the front traverses E of the Appalachians so will keep
PoPs in the 30-40% range. Temps Friday will be seasonable with 70s
for most of the area and perhaps 60s on the ern shore. NBM guidance
suggests warmer temps on Saturday, though this is dependent on the
frontal passage and continue to see a large spread in the guidance
and ensembles. For now, expecting 70s and 80s (warmest S/SW). Sunday
will be the coolest day in the forecast period with temps topping
out in the 60s, though some guidance suggests 50s across the N.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
As of 115 PM EDT Monday...

A cold front is slowly dropping south into the state. Scattered
rain and thunderstorms are expected to develop ahead of the
front later this afternoon and evening. Would expect northern
locations like SBY to see storms developing by 21Z, with RIC,
PHF, and ORF being impacted between 22Z-03Z. ECG has the lowest
confidence as storms may dissipate as they move south late this
evening; could still see some rain showers though. These storms
will be capable of producing strong wind gusts and hail. Added
mention of VRB wind gusts up to 30kt at PHF and ORF where threat
confidence is slightly better, though gusts to 30-40kt will be
possible at all terminals that see thunderstorms. Could have
brief VIS reductions in these storms as well. Storm/rain chances
end from north to south late this evening with skies trying to
eventually break by morning. Behind the front, expecting winds
to become northeasterly at 5-8kt into Tuesday morning.

Outlook: Most terminals will remain dry on Tuesday, however, there
is a slight chance of storms mainly from RIC and south late
tomorrow. Rain chances may return Wednesday as well before
drier conditions move in for later Thursday.
-- End Changed Discussion --

&&

.MARINE...
As of 325 AM EDT Monday...

High pressure is off the SE CONUS coast early this morning. SW winds
have diminished to ~15 kt with gusts to 20 kt. Seas are 4-5 ft N and
~3 ft S. The wind will continue to slowly diminish this morning and
become WSW. With the diminishing winds, anticipate that the SCAs for
the Ches Bay, Lower James River, and ocean will be allowed to expire
at 4 AM.

A weakening cold front drops south this aftn/evening with the
potential for some stronger storms along and ahead of the boundary
(most likely timing is between 3-10 PM). At least a few SMWs will
likely be needed for 34+ kt winds and potentially isolated large
hail. Winds turn to the NE behind the front and then to the E-SE on
Tuesday (staying sub-SCA through this timeframe). Conditions will
generally remain sub-SCA for the rest of the week with some
potential for seas to build to ~5 ft in the northern coastal waters
by Thursday/Friday as another weak cold front crosses the
region.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.

&&

$$

SYNOPSIS...SW
NEAR TERM...RHR/SW
SHORT TERM...SW
LONG TERM...SW/MRD
AVIATION...JKP
MARINE...ERI