Ashburn, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

423
FXUS61 KLWX 290036
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
836 PM EDT Sat Jun 28 2025

.SYNOPSIS...
Showers and thunderstorms are likely Sunday as a weakening cold
front drops southward into the area. Shower and thunderstorm
chances continue Monday and Tuesday as a stronger cold front
pushes through. Less humidity and drier conditions are expected
late next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
Storms will continue to gradually diminish through the late
evening hours with loss of daytime heating, with mainly dry
conditions through the overnight hours. Some patchy fog can`t be
ruled out late tonight, especially in locations that receive
thunderstorms during the daylight hours. Overnight low
temperatures will be in the upper 60s to the west of the Blue
Ridge, and lower to middle 70s further east.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Additional shower and thunderstorm chances are possible for portions
of the area Sunday as a decaying weak cold front drops southward
into the region. Current 12z CAM/synoptic guidance place this
boundary in the vicinity of the I-66/US-50 corridor or just south of
it into central VA Sunday afternoon. The boundary will have little
impact on temperatures with highs once again reaching back into the
upper 80s and low 90s. Humidity may drop off a little bit especially
for those the further north of I-66/US-50 where modeled PWAT values
look to fall into the 1.1 to 1.4 inch range Sunday afternoon and
evening. Areas south of I-66/US-50 will continue to deal with the
rich moisture laden air with PWATS around 2 inches. This will be the
primary area for convective development (south of I-66/US-50) Sunday
afternoon. SPC continues to maintain a Marginal Risk for most of
central and eastern VA during this timeframe with locally damaging
winds from wet microbursts and instances of flash flooding as the
primary threats. Storms will diminish with the loss of daytime
heating Sunday night with lows once again falling back into the
upper 60s and low 70s.

More widespread shower and thunderstorm activity is possible Monday
especially in northern parts of the forecast area as a washed out
front sits nearby. At the same time, will monitor the progression of
pre-frontal trough off to the west and encroaching strong cold front
approaching from the Ohio River Valley Tuesday. A warm and humid
airmass remains in between these two systems yielding ample
instability and subtle shear for storms to feed off of especially
during the peak heating period. SPC once again highlights the entire
area for a Marginal Risk (Level 1 out of 5) for severe weather.
Locally damaging winds and isolated instances of flooding will remain
possible with CAPE values greater than 2000 j/kg, 0-6 km shear
values less than 30 kts, and PWATS around or /above 2". Highs Monday
will climb back into the upper 80s and low 90s with heat index
values hovering close to 100 degrees. Lows Monday night will sit in
the low to mid 70s.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Potent shortwave-trough and accompanying sfc cold front will cross
the area Tuesday afternoon and bring an organized threat of severe
thunderstorms Tuesday afternoon into the evening. The main threat
will be damaging winds given expected fast storm motions, ample
shear and strong instability.

After trough axis passes Tuesday night, height rises and building
high pressure will result in seasonable warm and dry/tranquil
conditions through the remainder of the week. A reinforcing dry cool
front will push through the area Fri bringing cooler and drier air
mass for the upcoming Fourth of July weekend.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Convection will slowly diminish this evening. Areas of patchy
fog are possible tonight with vsbys remaining MVFR or greater at
most of the terminals outside of KCHO.

Additional showers and thunderstorms are possible Sunday afternoon
and evening as a decaying cold front sags southward into the region.
VFR conditions will prevail for most with sub-VFR reductions at
times for terminals south of KIAD and KDCA. Highest coverage of
thunderstorm activity looks to be down around KCHO-KSHD-KLYH-KRIC
with limited to no coverage up toward KBWI-KMRB where slightly
drier/stable air will push in. Winds will switch to the northwest at
less than 10 kts.  VFR conditions at all terminals Monday with
exception to brief MVFR conditions in strong thunderstorms during
the afternoon and evening hours. Numerous showers and thunderstorms
expected Tuesday afternoon, some possibly severe with damaging
winds. Dry conditions expected Wednesday and Thursday.

&&

.MARINE...
Sub-SCA level winds are expected to continue through Monday morning.
Winds will be light and variable Sunday. Southerly winds return
Monday with some channeling possible especially over the open
and middle waters Monday afternoon and evening. Expect the
chance of an SMW or two each afternoon and evening through
Monday as a result of scattered showers and thunderstorms. SCA
conditions expected late Monday night into Tuesday as the
gradient tightens ahead of an approaching cold front from the
Ohio River Valley.

SCA conditions likely Tuesday-Tuesday night. Severe t-storms are
likely Tuesday afternoon, which may require SMWs.

&&

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

&&

$$

SYNOPSIS...EST
NEAR TERM...CPB/EST
SHORT TERM...EST
LONG TERM...LFR
AVIATION...LFR/CPB/EST
MARINE...LFR/KJP/CPB/EST