Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 241834
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
234 PM EDT Sat Jun 24 2017

.SYNOPSIS...
High pressure will build west of the area through the rest of
the weekend and into next week as a series of weak cold fronts
cross the region. These fronts will bring with them little if
any precipitation. The sprawling surface ridge will then cross
the region Wednesday and settle over the western Atlantic Ocean
late in the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Partly to mostly sunny skies expected for the remainder of the
day with a mix of fair weather cumulus, some terrain driven
clouds, and some cirrus. Gusty west-northwest winds will
gradually diminish as the afternoon/evening progresses.
Temperatures will still be quite warm with highs from the mid
80s to near 90F, however dew points, and therefore humidity,
will continue to fall through the day.

For tonight, fair weather expected with ridging developing at
the surface. There may be some patchy fog in the favored
valleys. Lows will drop down into the 60s for most of the area,
except low 70s in the urban centers and along the
Potomac/Chesapeake, and dipping into the 50s west.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Upper level troughing over the northeastern US will define the
rest of the weekend and early week period, with a sprawling
surface high developing over the Midwest and Ohio Valley. This
will allow several weak frontal features to drop through the
northeast states during this time.

The first will cross portions of the northeast on Sunday. For
the most part this will remain off to our northeast, with
westerly flow and a mix of sun and clouds. Highs from 75-85F.
Fair weather continues Sunday night, with temperatures cooling
off into the 50s/60s.

The next weak frontal passage will occur on Monday, bringing
with it additional cumulus and perhaps a few isolated showers.
Highs Monday in the 70s to around 80F, dropping off at night
into the 50s to around 60F.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Upper level trough and its associated surface reflection will
slide east, and its axis will move across our area Tuesday. This
trough could create enough instability to allow for some
showers and thunderstorms mainly Tuesday afternoon. Temperatures
will be below normal with highs in the 60s and 70s, and lows in
the 40s and 50s.

Surface high pressure builds east Tuesday night, then moves offshore
late Wednesday, settling as a Bermuda high into Thursday as
flow becomes more southerly. Temperatures will be on the rise
and dry conditions continue into Thursday night. Guidance
suggest that upper level energy could bring showers and
thunderstorms over parts of our area Friday into Saturday. Cold
front approaches from west on Saturday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
VFR expected through the forecast period. Some gusty west-
northwest winds will linger into this afternoon (up to 20 knots
or so), but winds will gradually diminish through the remainder
of today and tonight. Additional gusts out of the west/northwest
up to about 20 knots possible again on Sunday and Monday. An
isolated shower could also occur Monday with a weak cold front,
but coverage will be extremely limited.

Scattered showers and thunderstorms possible Tuesday as upper
air disturbance moves through, which could cause periods of sub-
VFR conditions. VFR conditions return Tuesday night into
Thursday with high pressure building in.

&&

.MARINE...
Winds will gradually decrease through the remainder of the
afternoon, with SCA expiring by evening. There may be a
resurgence in winds overnight as a weak trough passes through,
but have kept winds below SCA criteria for now.

Additional gusts up to about 20 knots likely Sunday
afternoon/evening across the northern Chesapeake Bay, so have
issued a Small Craft Advisory from 1 PM through 10 PM. As cooler
air moves in over warmer water temperatures Sunday night,
increased mixing may lead to these winds persisting through
Sunday night.

Additional gusts near SCA criteria may occur Monday and Monday
night with persistent west-northwest flow and weak frontal
passages.

Scattered showers and thunderstorms possible Tuesday
as upper air disturbance moves through. Conditions improve Tuesday
night with high pressure building in and weather remaining dry into
Thursday. Winds gusts will be below the small craft advisory
criteria Tuesday through early Thursday. Wind gusts will increase
Thursday afternoon.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     ANZ530>533-535-536-538>541.
     Small Craft Advisory from 1 PM to 10 PM EDT Sunday for
     ANZ530>532-538>540.

&&

$$
SYNOPSIS...MM
NEAR TERM...MM
SHORT TERM...MM
LONG TERM...IMR
AVIATION...MM/IMR
MARINE...MM/IMR



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