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171
FXUS61 KAKQ 211949
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
349 PM EDT Fri Jun 21 2024

.SYNOPSIS...
High pressure off the Mid Atlantic coast slowly shifts south
through the end of the week, leading to an extended period of
hot weather this weekend and again next week. There is a small
chance for rain Sunday evening into Monday, and again on
Thursday, but many places will stay dry.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 215 PM EDT Friday...

Key Message:

- Dry and very warm this afternoon, mild tonight.

High pressure remains in control over the region this afternoon
with dry/very warm conditions prevailing. Temperatures as of 2
PM range from the upper 80s to lower 90s across the region, and
will rise into the low to mid 90s for daytime highs (80s at the
coast). Skies are generally mostly sunny with just some
scattered cumulus. Overnight lows inch up a few degrees compared
to last night and look to be in the upper 60s or lower 70s
(warmest in the urban corridors and near the coast).

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
As of 330 PM EDT Friday...

Key Messages:

- Hot temperatures expected Saturday and Sunday with maximum
temperatures both days in the mid/upper 90s to around 100 F.

- Heat indices of 100 to 105 F are expected on Saturday, and heat
indices of 105+ F are expected on Sunday.

The hottest temps are still expected this weekend. Tomorrow, high
pressure will shift further offshore to our SE, allowing winds at
the surface to become SSW. While the ridge gradually begins to break
down, 850 mb temps of 20-23C will be common across the area. This
yields highs in the upper 90s to around 100 F inland (especially
across the Richmond metro) and mid 90s closer to the coast. Similar
to this afternoon, dewpoints will mix out tomorrow afternoon,
generally dropping into the mid to upper 60s. This should help to
keep heat index values somewhat in check, but heat index values of
~103 to 105 F will still be common (especially inland and urban
areas). In addition, wet bulb globe temperatures (WBGT) will be in
the upper 80s tomorrow which would suggest the potential for
significant heat issues. As a result, even though we may fall just
short of official Heat Advisory criteria decided to err on the side
of caution and issued a Heat Advisory for much of central
VA/Richmond Metro down into the Hampton Roads metro. Left out
southwestern portions of the area and North Carolina where we likely
see slightly cooler air temperatures and more mixing. Also left out
the Eastern Shore, where an afternoon sea-breeze should help to keep
temperatures in check. Interior portions of the MD Eastern Shore
will still have heat index values of 100 to 102 F. It should also be
noted that overnight lows in the mid-upper 70s will not provide much
relief, potentially compounding the heat issues for those who do not
have access to air conditioning.

The core of the heat is expected to shift SE some for Sunday,
though hot temps will remain over the entire forecast area with 850
temps remaining in the 20-23C range. High temperatures will be
similar to Saturday, if not a degree or two higher in spots
(especially east). Highs range from around 100 F across the Richmond
metro, to the mid to upper 90s elsewhere. Dewpoints on Sunday will
be higher compared to Sunday due to strengthening southwesterly sfc
flow. The flow aloft also shifts more W/WSW and 700 mb RH fields
show a noticeable increase in moisture across the area. This is
likely to prevent the degree of afternoon mixing seen today (Friday)
and Saturday. In this realm, dew points only drop into the upper 60s-
low 70s in the afternoon, producing heat indices well into heat
advisory range (105-110 F) for much of the area. While a few
locations could near 110 F, not enough confidence at this point for
any excessive heat watches. WBGT`s in the upper 80s to around 90
also suggest the potential for significant heat stress for those
outdoors and especially those participating in strenuous activities.
Additional Heat Advisories will likely be needed for much of, if not
all of the forecast area Sunday. There will again not be much relief
from the heat Sunday night with lows in the mid to upper 70s.

The other part of the forecast Sunday is any potential for later
afternoon/evening convection. Those higher dew points support higher
sfc-based instability and upper-level height falls from an
approaching shortwave could set off isolated storms, especially
later in the day. With the hot temps, steep low-level lapse rates
and high DCAPE could support a damaging wind threat if any storm can
develop. SPC has introduced a marginal risk for our northern tier of
counties. Shear is weak so not expecting much in the way of
organized svr wx. With uncertainty in coverage very high, PoPs are
only 20-30% (highest across the north) Sunday afternoon. Will want
to keep an eye on the various CAMs as they come into range over the
next 24-36 hrs. A weak cold front slowly pushes through the area
Sunday night suggesting perhaps some higher coverage of showers or
storms. Have chance PoPs for most of the area overnight (highest
coverage still expected N). Still, this does not look to be a
widespread beneficial rainfall to alleviate the developing drought
over the area, with only ~0.10" of QPF in the forecast for portions
of the area through Sunday night.
-- End Changed Discussion --

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
As of 330 PM EDT Friday...

Key Messages:

- Another hot day Monday with higher humidity. Scattered storms also
possible across the southeast.

- The heat builds again midweek, with temperatures again increasing
well into the 90s to near 100.

- Flash drought conditions developing.

It remains hot Monday, but air temps will not be as high as Sat/Sun.
However, the humidity levels will be even higher as dew points stay
in the low-mid 70s for most of the area. Heat indices of 100-105 F
are expected for most of the area, though SE VA and NE NC could see
heat indices in excess of 105 F. The one caveat is potential
afternoon convection developing along the "cold" front in these same
areas which could mute the upper end temp potential. As of now,
going with highs in the mid 90s areawide (upper 80s to lower 90s
Eastern Shore). Regarding convection, guidance continues to hone in
on southeastern VA and northeast NC for the best storm chances. With
less coverage W of I-95 with the frontal boundary E/SE of these
areas. Model instability fields show high MLCAPE (1500-2000 J/kg,
highest NE NC) ahead of the boundary. Weak shear will again prevent
much in the way of storm organization, though the high CAPE and
DCAPE again suggests damaging downburst winds and frequent lightning
as potential threats.

The cold front does very little to provide any heat relief as temps
Tuesday remain in the low-mid 90s. Even hotter Wednesday and we
again could be talking about temps nearing 100 F. This ultimately
makes sense given the downslope NW flow and still warm 850 mb temps
around 21-24C per both the 12z/21 GFS and ECMWF. It will be drier,
due to the downslope flow, with dew points perhaps dropping back in
the mid 60s as compared to the low-mid 70s seen on Monday. By
Thursday, another cold front approaches from the NW and will
continue chance PoPs for the area, favoring the higher coverage
across the S and SE. While this front looks to have a little more
moisture to work with, the chances for widespread rainfall remain
low. Temps may try to drop closer to average for the later part of
the week, with highs in the upper 80s to around 90 F.

On that note, it continues to not look promising for widespread
rainfall, as many places will see little to no rain through the
period. The latest NBM probabilities are not optimistic either with
the probability for at least 0.50" of total rainfall through the
midweek period 10-20% across the W/NW and 30-50% across the E/SE.
This will only exacerbate the recent dry conditions and set us up
for what can be considered a "flash drought". More information on
this can be found on CPC`s Probabilistic Hazards Outlook page at
www.ncep.cpc.noaa.gov or drought.gov.
-- End Changed Discussion --

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
As of 215 PM EDT Friday...

Primarily VFR conditions are expected through the 18z TAF
period. Afternoon FEW to SCT cumulus this afternoon (~4 to 5k ft)
will diminish with the loss of daytime heating later this
evening. There is some potential for MVFR CIGs to work into far
SE portions of the area late tonight into early Saturday
morning, but confidence remains low. S/SSE winds around 5-10 kt
this afternoon, becoming southerly ~5 kt tonight.

Outlook: Dry and VFR conditions are expected to prevail through
Sunday afternoon as high pressure remains centered off the
coast. There is a low chance for some isolated to widely
scattered storms Sun evening and again Mon afternoon into Mon
evening.

&&

.MARINE...
-- Changed Discussion --
As of 330 PM EDT Friday...

Updated Marine section coming shortly...


Key Messages:

- Sub-SCA marine conditions expected through Saturday morning.

- An elevated southerly wind is forecast to develop late Saturday
through Sunday night. The best chance for SCA conditions is later
Sunday afternoon into Sunday night.

- Moderate rip current risk at all areas beaches continues Friday.
At least a moderate risk continues through the weekend.

High pressure remains centered off the Mid-Atlantic coast early this
morning. The wind is primarily S 5-10kt and locally S 10-15kt in the
middle Ches. Bay. Seas range from 3-4ft S to 2-3ft N. High pressure
remains centered off the coast today into tonight. The wind will
mainly be S to SE 5-10kt this morning into early aftn. A SSE wind is
expected to increase to ~15kt with gusts up to 20kt for the Ches.
Bay and ocean N of Cape Henry later this aftn and evening, and 10-
15kt elsewhere. By later this evening and into tonight the wind is
expected to become SW and diminish to 8-12kt. Seas are expected to
be ~3ft today into tonight, with 1-2ft waves in the Ches. Bay, which
will briefly build to 2-3ft with the late aftn/evening diurnal
increase in wind.

High pressure settles off the Southeast coast Saturday into Sunday.
A SSW wind will generally be 5-10kt Saturday morning into early
aftn, with a late aftn/early evening diurnal shift to SSE and
increase to ~15kt for the Ches. Bay and ocean N of Cape Henry (10-
15kt elsewhere). Seas build to 3-4ft N (mainly 2-3ft S) with waves
in the Ches. Bay building to 2-3ft with the diurnal shift and
increase in wind. A weakening cold front slowly approaches from the
NW later Saturday night through Sunday night. A SW wind potentially
increases to 15-20kt for the Ches. Bay and northern ocean later
Saturday night into early Sunday, with marginal SCA conditions
possible in the Ches. Bay. The pressure gradient tightens over the
ocean Sunday aftn/evening with a ~20kt SSW wind possible, which
could result in seas building to 4-6ft N of Cape Charles later
Sunday aftn into Sunday night. Additionally, a SW wind potentially
increases to 15-20kt for the Ches. Bay Sunday night with marginal
SCA conditions possible. The pressure gradient slackens Monday into
Tuesday as the weakening cold front settles into the area and washes
out. High pressure rebuilds offshore by the middle of next week with
sub-SCA southerly flow returning. Seas will mainly be 2-3ft Monday
into the middle of next week with 1-2ft waves in the Ches. Bay.

Rip currents: A moderate rip risk will continue today for all
beaches with some SE swell ~3ft with ~8s periods. An elevated rip
risk likely continues through the weekend. Confidence of moderate is
higher for the northern beaches Saturday and Sunday, but southerly
flow and a longshore current may preclude a high risk.
-- End Changed Discussion --

&&

.CLIMATE...
-- Changed Discussion --
Record high temperatures for Saturday, June 22:

- RIC: 101 (1933)
- ORF: 99 (1981)
- SBY: 98 (1988)
- ECG: 98 (1942)

Record high minimum temperatures for Sunday, June 23:

- RIC: 76 (2010)
- ORF: 79 (2015)
- SBY: 75 (1925)
- ECG: 78 (2015)

Record high temperatures for Sunday, June 23:

- RIC: 101 (1988)
- ORF: 99 (2015)
- SBY: 99 (1988)
- ECG: 99 (2011)
-- End Changed Discussion --


&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...Heat Advisory from 11 AM to 8 PM EDT Saturday for VAZ048-061-
     062-064-068-069-075>078-080>086-088>090-092-093-095>098-
     509>525.
MARINE...None.

&&

$$

SYNOPSIS...AJB/SW
NEAR TERM...AJB
SHORT TERM...AJB/SW
LONG TERM...AJB/SW
AVIATION...AJB
MARINE...AJZ/AM
CLIMATE...AKQ