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dc discuss

Office: LWX

FXUS61 KLWX 111537

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1137 AM EDT Thu Aug 11 2022

A cold front front will stall out over central Virginia today
before a reinforcing cold front passes through tonight. High
pressure will build overhead Friday through Saturday before
moving offshore Sunday. An upper-level trough will remain over
the area for the early and middle portion of next week, and
disturbances associated with the trough may bring unsettled


UPDATE: Only minor changes were made to the overnight foreacast,
with the introduction of some slight chance POPs overnight. This
is in response to a vorticity max sliding through the area
during the overnight hours which will provide just enough lift
for a few showers. Nothing of real consequence, but enough for a
few areas to pick up a few hundredths.

PREVIOUS DSICUSSION: The cold front will stall out over central
Virginia into extreme southern Maryland later this morning, so
increasing sunshine is expected from northwest to southeast this
morning. However, a few popup showers and thunderstorms are
possible near the cold front over central VA and extreme
southern MD late this morning into this afternoon. Highs will be
in the mid to upper 80s for most locations today (60s and 70s
in the mountains).

A reinforcing cold front will approach from the northwest late
this afternoon before passing through tonight. A few showers and
perhaps a thunderstorm are possible with the frontal passage,
especially over the Allegheny Highlands late this afternoon and
evening, where the frontal passage will be closer to peak
heating. Elsewhere, an isolated shower cannot be completely
ruled out this evening, but most of the time will be dry.

The cold front will settle to the south overnight and Canadian
high pressure will build toward the area from the northwest. A
surge of cooler and drier air will move into the area overnight,
causing it to feel much less humid than recent nights. Lows will
range from the 40s in the Allegheny Highlands, to the 50s and
60s elsewhere.


Canadian high pressure will build overhead during this time,
causing cooler conditions for this time of year along with low
humidity. Highs will be in the upper 70s to lower 80s for most
locations (60s to lower 70s in the mountains), and lows will be
in the 50s to lower 60s for most locations (40s in the Allegheny
Highlands. Plenty of sunshine is expected as well.


For the end of the weekend, increasing moisture from ahead of an
approaching low pressure system will bring slight chance PoPs to the
area later in the day on Sunday. As the low pressure system
approaches for the early part of the work week, expect a typical
diurnal cycle for chances for showers and thunderstorms for a
majority of the area for the afternoon and evening both days. As the
front becomes more overhead on Tuesday, expect better chances for
widespread rain on this day, similar to the previous Wed/Thurs event

By Wednesday, the front should be mostly passed with only
some lingering moisture across the eastern half of the CWA as high
pressure builds in from the northwest. Nothing too daunting for the
long term period aside from a few showers and thunderstorms for the
start of the work week. Daytime temperatures will top out at or just
below normal for early/mid August (upper 70s to low 80s for most


Dry conditions are expected most of the time. Drier air behind
a cold front will move into the area between 12z and 15z for
most of the terminals, causing northwest winds and VFR
conditions. However, the front may get hung up near KCHO, so a
popup shower or thunderstorm cannot be ruled out this afternoon.
Even for KCHO, the better chance for convection will be to the

A reinforcing cold front will pass through this evening. An
isolated shower cannot be ruled out, but most areas will be dry.
Northwest winds are expected behind the cold front with gusts
around 15 to 20 knots overnight through Friday. High pressure
will bring VFR conditions through Saturday night.

VFR conditions expected early on Sunday before a few showers and
thunderstorms approach the western terminals by mid-evening. These
chances for occasional ceiling drops will continue through late
Tuesday along with some room for the potential of patchy to dense
fog both days, mainly for KMRB and KCHO.


A cold front will stall out to the south this afternoon. A
popup shower/t-storm is possible near the cold front across the
southern waters (lower Tidal Potomac and Chesapeake Bay near
Smith Point).

A reinforcing cold front will pass through tonight. A pressure
surge behind the cold front will cause north to northwest winds
to increase. An SCA is in effect for the Bay and lower Tidal
Potomac River late tonight through Friday. The SCA may need to
be extended into the upper Tidal Potomac River, but confidence
was too low at this time given marginal winds progged to be in
the mixing layer.

High pressure will build over the waters Friday night through
Saturday night. An SCA may be needed for portions of the waters
Friday night into Saturday.

SCA criteria winds will be possible with southerly channeling taking
place, especially for the lower Chesapeake Bay zones. A few showers
and even rumble of thunder may occur Monday and Tuesday afternoon
and evenings, isolated SMWs may be possible.


MARINE...Small Craft Advisory from midnight tonight to 6 PM EDT Friday
     for ANZ530>534-537>543.