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FXUS61 KLWX 271405
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1005 AM EDT Thu Jun 27 2024

.SYNOPSIS...
A cold front exits the area later today bringing with it
slightly cooler temperatures. High pressure builds in from the
northwest through Friday before moving offshore Friday night.
Heat and humidity return this weekend along with increased
thunderstorm chances as a series of fronts push through the
region. High pressure arrives early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
MORNING UPDATE: No changes planned for the morning update at
this time, see previous discussion.

PREVIOUS DISCUSSION: As a cold front will exit the area by this
afternoon. Some isolated showers/t-storms could develop in the
central Shenandoah Valley and Virginia Piedmont in the
afternoon, but guidance has trended drier with the subsidence
behind the exiting shortwave aloft and high pressure building in
from the northwest. Temperatures lower behind the cold front
into the 80s to low 90s, but dewpoints look to remain in the
low-mid 60s during the day, dropping into the upper 50s
overnight with lows temps in the 60s to near 70 east of the
mountains.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A quick-moving area of high pressure passes to our north on
Friday. Mostly dry conditions are expected during the day, but
some showers could develop in the afternoon/evening around the
Shenandoah Valley and Virginia Piedmont as the center of high
pressure swiftly moves offshore by the evening and a shortwave
approaches from the northwest. Temperatures look relatively
cooler, topping out in the upper 80s. Lows hover in the 60s to
mid 70s.

As high pressure moves offshore, south/southwesterly return flow
will usher in a warmer, more humid air mass for Saturday. Though
temperatures are currently forecast to top out in the upper 80s
to low 90s, with dewpoints in the mid-upper 70s means apparent
temps pushing into the 100s. Showers and thunderstorms are
expected in the through the day as well, which will only add to
the "soupy" conditions. The warm front lifting through will kick
off some showers and storms in the morning, then as we enter the
afternoon and evening with more instability, severe potential
becomes a concern.

Overnight, not much relief from the heat is expected as lows
hover in the 70s for most, and around 80s in the metros.
Apparent temps will likely be a good 5-10 degrees warmer than
that.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
To finish out the weekend heading into the Independence Day holiday,
active weather is expected for Sunday as a cold front approaches
from the Ohio River Valley. Ample heating of the surface carries
high temperatures into the low/mid 90s. Multi-ensemble solutions
favor a seasonably moist air mass entering the Mid-Atlantic region
with dew points rising into the mid 70s. This combination of heat
and humidity carries heat indices to around 100 to 105 degrees. Such
levels near Heat Advisory thresholds so this will bear watching
heading into the weekend. Besides the summertime heat and humidity,
convection will likely be on the increase as a strong frontal system
enters the picture. The local area appears to be on the southern
flank of the stronger belt of mid-level westerlies, generally
running around 35 to 45 knots. Model soundings show primarily
unidirectional westerlies in the column with ample downdraft CAPE
profiles. Thus, a damaging wind signature may accompany any of the
stronger updrafts on Sunday. While not directly outlooked, the Storm
Prediction Center extended discussion does reference some degree of
severe weather threat is possible.

Depending on frontal timing, the threat for showers and
thunderstorms should gradually wane through the overnight with a dry
start to the work week expected. A stout ridge of high pressure
tracks in from the Northern Plains and Great Lakes region. Forecast
pressures range from 1020 to 1024 mb which is pretty strong given
the time of year. Consequently, Monday`s forecast highs top out in
the upper 70s to low 80s, locally in the upper 60s to mid 70s across
mountain locales. This comes with a prevailing north to
northwesterly wind and mainly sunny skies. It will certainly not
feel like the first day of July as overnight lows fall into the mid
50s to low 60s, locally a bit milder along and east of I-95.

As the upper trough from the weekend pinches off over the western
Atlantic, heights will build over the region as a strong ridge
expands from the south-central U.S. This promotes a warming trend
from Tuesday through much of the week. Multi-model trends show
low/mid 90s becoming more commonplace toward the middle/latter
portion of the work week. This likely makes for a hot Independence
Day holiday. The risk for showers and thunderstorms also return to
the forecast by Wednesday.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
Some showers and thunderstorms could develop Thursday
afternoon, with the greatest chance for CHO. Winds turn NW
behind the cold front by late morning, and could gust up to 15kt
at times. Mostly dry conditions follow and continue into Friday
as high pressure passes to the north and winds turn SW. Some
shower activity is possible again Friday afternoon/evening but
should be isolated, and again most likely near CHO if so.

Sub-VFR conditions are likely Saturday with any showers and
thunderstorms that move across the terminals. A warm front lifts
through the area in the morning/afternoon with some shower
activity expected, and more is expected in the afternoon and
evening with the potential for strong to severe storms.

Ahead of a strong cold front, expect some restrictions on Sunday as
showers and thunderstorms could impact the terminals. There may be
some severe component to these storms as well. This front pushes
through Sunday evening with winds shifting to northwesterly in the
wake. A return to prevailing VFR conditions is likely by Sunday
night, continuing into Monday. High pressure takes shape over the
region on Monday with mainly northerly winds.

&&

.MARINE...
Sub-SCA winds are expected today with northwest winds behind the
exiting cold front. Late tonight into early Friday morning,
winds over the waters may approach SCA criteria as high pressure
offshore presses southward before diminishing in the late
morning and early afternoon. As winds increase out of the SW,
SCAs may be needed Friday evening and again with strengthening
southerly flow and a passing warm front on Saturday.

Hazardous conditions are possible on Sunday over the area waterways.
This is in response to the potential for afternoon/evening showers
and thunderstorms, some of which could become severe depending on
how the threat materializes. Thus, Special Marine Warnings may be
required over portions of the waters. Behind the cold front, winds
could push to near Small Craft Advisory levels on Sunday night into
Monday morning. This may persist a bit longer as models show a
decent period of northerly channeling effects.

&&

.TIDES/COASTAL FLOODING...
Expect tidal anomalies to slowly drop today behind a cold front. No
coastal flooding is expected through Friday before water levels ramp
up over the weekend. A warm front tracks across the area early
Saturday leading to a shift to southerlies. The Stevens Ensemble
shows a potential for Action to perhaps Minor flood stages over the
weekend at the more sensitive sites.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...CJL/CAS
SHORT TERM...CAS
LONG TERM...BRO
AVIATION...BRO/CAS
MARINE...BRO/CAS
TIDES/COASTAL FLOODING...LWX