Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 150749
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
349 AM EDT Tue Oct 15 2019

.SYNOPSIS...
High pressure will continue to build into New England today as a
dry cold front pushes through the region. A strong surface low
pressure system will develop and move across the Ohio Valley on
Wednesday, then re-develop over southeastern Virginia, before
moving up the east coast towards New England Wednesday night
into Thursday. High pressure returns Friday into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure will dominate the weather pattern today, with
sunny skies expected once again. Temperatures will be seasonably
warm, with highs into the low 70s across much of the area.

Elsewhere, we there are two features of interest to monitor. The
first being a developing surface low, currently in the northern
Plains. This system will track east into the Great Lakes and
strengthen today. Additionally, surface low pressure will be
forming along the Gulf coast as a piece of upper-level energy in
the southern jet interacts with the baroclinic boundary along
the coast.

The cold front associated with the northern low will be
approaching on Tuesday night, turning winds out of the
southeast, and eventually the south. Expecting some low clouds
east of the Blue Ridge as a result late Tuesday night, as well
as some isolated showers along the Blue Ridge.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The main show will wait until Wednesday to materialize. The
strong upper-level trough digging down across the Mid-Atlantic
will act to lift the weaker southern stream energy north across
our region. As the surface low moves out of the southeast and up
the east coast, the cold front will be sweeping through the
area, so thinking we see a prolonged period of moderate rain
across much of the area. Cold front pushes through by Wednesday
afternoon, meanwhile, the secondary surface low will be sliding
up the eastern seaboard and gaining strength. This will result
in more intense rainfall across the Delmarva Peninsula and into
central/northeast MD. QPF amounts in excess of half an inch are
expected east of the Blue Ridge, with heavier amounts (1-1.25
inches) expected along the western shore of the Chesapeake Bay.
This region could also see some isolated rumbles of thunder
during the afternoon.

Low pressure will quickly depart to the northeast, and skies
will begin to clear into Wednesday night. Winds will also be on
the increase into Wednesday night behind the aforementioned
cold frontal passage. The highest wind gusts will be in the
higher elevations and on/near the waters, where 30-35 mph gusts
aren`t out of the question. Additionally, remnant upslope
showers are likely along/west of the Allegheny front. These will
mostly be rain, but could see some snow mix in at the highest
peaks, where surface temperatures will near the freezing mark,
with temperatures aloft below freezing as well.

Perhaps some lingering cloudcover along the Mason-Dixon line as
we head into Thursday, but dry across the entire area. Big story
will be the strong west-northwesterly winds up to 30 mph.
Temperatures will only be in the upper 50s to near 60 as well.
Slightly cooler temperatures overnight Thursday, with low to
mid 40s for much of the area. The higher elevations will be in
the low to mid 30s, so some frost/freeze headlines may be
needed in a few spots.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
High pressure will build overhead Friday through Saturday, bringing
dry and seasonable conditions. High pressure will move offshore
Saturday night into Sunday while weak low pressure associated with
the southern stream of the jet moves through the Gulf Coast States.
There is a chance that southern stream moisture overruns cooler air
in place, causing some rain later Sunday into Sunday night. However,
confidence is low at this time since guidance diverges on how much
southern stream moisture will make it into our area.

A deepening upper-level trough to our west is expected for early
next week, and this will bring warm conditions for this time of
year, but with a deep southerly flow this will also bring the chance
for showers.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
VFR conditions expected today, under the influence of high
pressure. Not seeing much in the way of fog near CHO/MRB, so
thinking chances are pretty slim, as dewpoint depressions are
still quite high. But can`t rule it out around sunrise. Not
confident in sub-VFR conditions at this time though.

Clouds will be on the increase tonight ahead of a cold front
approaching from the west, which will push through Wednesday.
southeast flow ahead of the front could bring in some low
marine-layer clouds (perhaps IFR) during the overnight hours.
Expect CIGs to gradually rise through the day, with MVFR
expected until the front pushes through. MVFR VISBs will also be
possible in moderate rain.

VFR will prevail through Wednesday night. Winds will increase
Wednesday night as well out of the WNW. If the core of the
winds do not mix to the surface, then a low level wind shear
set-up would be possible.

VFR conditions are expected for Friday and Saturday with high
pressure in control.

&&

.MARINE...
Winds will be light today, under the influence of high pressure.
A cold front will approach from the west Tuesday night into
Wednesday, along with a low pressure sliding by to our
southeast. Southerly channeling could lead to some gusty winds
near SCA criteria throughout the day on Wednesday, so have
issued a Small Craft Advisory to reflect such. Behind the cold
front, winds will really pick up, so SCA will likely be
extended, with Gales possible into Thursday. SCA conditions
likely continue into Thursday night, before diminishing into
Friday morning.

High pressure will likely control the weather pattern for Friday and
Saturday, causing winds to be below SCA criteria for most of the
time.

&&

.TIDES/COASTAL FLOODING...
High pressure will move offshore today, and a cold front will
approach from the west tonight into Wednesday. This will cause a
southeast flow to strengthen a bit, and this will lead to elevated
water levels. Minor flooding is possible for sensitive areas with
the high tide cycle later this afternoon into tonight, and again for
Wednesday. A strong offshore flow will develop behind the cold front
Wednesday evening, and anomalies should drop sharply.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 6 AM to 6 PM EDT Wednesday for
     ANZ533-534-537-541>543.

&&

$$
SYNOPSIS...CJL
NEAR TERM...CJL
SHORT TERM...CJL
LONG TERM...BJL
AVIATION...BJL/CJL
MARINE...BJL/CJL
TIDES/COASTAL FLOODING...BJL


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