Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 150800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Fri Mar 15 2024

.SYNOPSIS...
A cold front will cross the area this afternoon and evening bringing
showers and thunderstorms to the area. Cool high pressure
briefly returns to the area Saturday before a secondary cold
front crosses Sunday into early next week. This brings a return
to below normal temperatures next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The latest radar trends across the area have shown a decrease in
convective coverage. What is currently pushing through is what
remains from severe weather which impacted the Ohio Valley the
previous evening. Any lightning activity has ceased within the
last couple of hours. Currently light showers extend from
north-central Maryland back to the eastern West Virginia
panhandle. A rather pronounced outflow boundary is surging
southward to southern Maryland with peak wind gusts up to
around 20 to 30 mph. Overall, expect shower activity to
dissipate in the next hour or two as instability has become
exhausted per the RAP objective analysis.

Early morning observations are very mild for mid-March
standards. Most areas sit in the upper 50s to mid 60s
accompanied by winds mainly out of the south to southwest. The
current exceptions are places which have seen the mentioned
outflow move through which led to a shift to north to
northwesterlies. A warm advection pattern will maintain well
above average temperatures yet another day. Today`s highs are
expected to range from upper 60s to mid 70s, locally down into
the 50s to low 60s across the higher terrain.

An upstream cold front currently extending from northeastern
Ohio back toward southern Illinois will play a key role in
today`s weather. This boundary is forecast to cross through the
local area during the afternoon to early evening before sagging
south into the night. Expect scattered to numerous showers to
cross through as this system approaches. The air mass is fairly
dry so it may take some saturation of the lower atmosphere to
see appreciable rainfall. Although convective chances are not
terribly high, isolated thunderstorms are in the forecast mainly
from I-66/U.S. 50 southward. This spans the afternoon into early
evening hours before any remaining instability wanes. MUCAPE
values largely top out in the 200-400 J/kg range. Rain chances
diminish into the night with low temperatures in the mid 30s
over the mountains to the 40s elsewhere.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Behind the exiting frontal system, high pressure briefly returns
for the first half of the weekend. This will promote a dry
forecast over the region with cooler temperatures owing to a
period of northwesterly winds. While still above average for
this time of year, it will feel cooler as highs are expected to
be in the 60s with 50s across mountain locales. As the
anticylone exits the Atlantic coast, winds shift back to
southerly for the second half of the day. Skies should be filled
with plenty of sunshine despite some passing clouds. Nighttime
temperatures remain mild given the return flow.

The next frontal system of interest currently resides over
northern Alberta. Over the next couple of days, this feature
will race southeastward, bringing it to the Appalachian chain by
early Sunday. This system will bring another round of
northwesterly winds, albeit more gusty than the previous day.
Afternoon gusts could reach 20 to 25 mph, while being closer to
35 to 45 mph over the Allegheny Front. This could bring a few of
the higher peaks to near Wind Advisory criteria. While this
cold front may bring a few showers to western Maryland early
Sunday, the day will largely be dry. Forecast highs are mild
which generally sit in the upper 50s to 60s, with 40s to low 50s
in the mountains. Winds may stay up a bit into the night with
low temperatures in the 30s to low 40s, with 20s along the
Alleghenies.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The first half of next week looks colder than normal as large scale
troughing pivots across the eastern CONUS. Embedded shortwaves may
bring periods of mountain snow showers Monday and Tuesday, and a
flurry, sprinkle, or shower or two are possible east of the
mountains depending on the strength of each of the waves (though
most if not all of the time/area east of the Alleghenies should stay
dry). This period early in the week will also feature blustery
conditions in a tight gradient between low pressure to the northeast
and high pressure building in from the west.

Moderating temperatures are likely heading into the second half of
next week. As the pattern shifts a bit, another storm system may
develop which would bring more widespread (likely liquid)
precipitation chances to the region later next week, but uncertainty
surrounds the specifics given the extended time range and shifting
pattern locally.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
An outflow boundary from earlier convection continues to drop
southward toward southern Maryland. Any impacts to the terminals
have already occurred at this point. The shift to north to
northwesterlies at the D.C. and Baltimore terminals should be
somewhat brief with winds returning to south-southwesterly.
Otherwise, a strong low-level jet overhead will promote
enhanced low-level wind shear through late this morning.

For the rest of the day, an approaching cold front will bring a
shift in the pattern this afternoon and evening. Although VCTS
is shown for a 4-hour period (roughly 2 PM-6 PM) at all
terminals, the better threat extends from the D.C. terminals and
points southward. However, there is enough uncertainty to keep
VCTS at the northern terminals. While not explicitly shown,
brief restrictions and gusty winds are possible during the
period of convection. This cold front brings a shift to
northwesterly winds which persist into the first half of
Saturday.

For the remainder of the weekend, expect VFR conditions at the
area terminals. With high pressure shifting offshore, winds
turn over to southerly on Saturday afternoon while continuing
into the night. The next cold front takes aim at the area early
Sunday leading to gustier northwesterly flow. Gusts up to 20 to
25 knots are possible behind this front.

Mainly VFR Mon-Tue with blustery NW winds; gusts to 30 kts
possible.

&&

.MARINE...
Southward sinking outflow boundaries continue to bring 25 to 35
knot winds to portions of the waterways. As such, Marine Weather
Statements and Special Marine Warnings have been hoisted over
the past couple of hours. This threat should gradually wane as
these outflows exit the waters by 5 to 6 AM. Otherwise, Small
Craft Advisories remain in effect over the lower tidal Potomac
and southern third of the Chesapeake Bay until 2 PM this
afternoon.

For the remainder of the day, some convection may impact the
waters this afternoon and evening which would bring some gale-
force winds to the waters. As the cold front pushes through
early this evening, northerlies ensue in the wake. This may
bring Small Craft Advisory criteria to the southern waters late
this evening into early Saturday. With a shift back to
southerlies, some channeling effects may yield additional
advisories along the Chesapeake Bay for Saturday evening into
portions of the night. A quick moving cold front leads to a
return to northwesterlies on Sunday. Winds near advisory levels
at times.

Blustery northwest winds and mainly dry conditions are expected
Monday into Tuesday. Gusts of 20 to 30 knots are most likely.

&&

.TIDES/COASTAL FLOODING...
Elevated tide levels in southerly flow are forecast through tonight.
The higher of the two tides astronomically is the morning, and this
is the most likely tide to experience minor flooding, especially for
the typically more vulnerable shoreline locales.

Depending on the timing of a wind shift to offshore heading into
Saturday, flooding chances may linger into the morning. Overall,
though, tide levels will decrease through the weekend. Persistent
offshore flow could lead to some lower then normal levels early next
week, as well.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ533-
     534-537-543.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...DHOF
AVIATION...BRO/DHOF
MARINE...BRO/DHOF
TIDES/COASTAL FLOODING...DHOF


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