Area Forecast Discussion Issued by NWS Sterling, VA
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000
FXUS61 KLWX 131920
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
320 PM EDT Wed Mar 13 2024
.SYNOPSIS...
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Surface high pressure will continue to influence the Mid-Atlantic
region through Thursday with well above normal temperatures and
mostly dry conditions. A low pressure system will approach the
area Friday, bringing a chance of showers and a few
thunderstorms. Another low pressure system may impact the
region Sunday into Monday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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The center of surface high pressure extends eastward from
Florida this morning. A shortwave trough is overhead producing
mid and high level clouds. However there has been enough
filtered sunshine for temperatures to rise into the upper 60s to
mid 70s.
Skies clear out again tonight as the shortwave moves away. Some
more high clouds may move back in late tonight though. Overnight
lows will be in the 40s for most of the area with light winds
continuing. Some sheltered valleys may fall into the 30s.-- End Changed Discussion --
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
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The high remains off the southeast coast Thursday with ridging
maximized overhead. Flow will become more southwesterly, which
should boost highs into the mid 70s to near 80 despite some
patchy high level clouds. The low level airmass will remain
fairly dry and should warm quickly.
Meanwhile, low pressure will be moving toward the southern Great
Lakes by Thursday night. The associated warm front will likely
extended across PA, leading to well above average low
temperatures for the overnight hours. Most areas will likely
only drop down into the mid to upper 50s. A few showers are
possible along the Alleghenies and closer to the Pennsylvania
border, but deeper moisture and lift is expected to remain north
of the area.
The low will quickly move toward New England Friday, but with
the front nearly parallel to the upper flow, it will be slow to
push southeast. With the relatively dry low level airmass
remaining in place and a lack of strong upper support as well,
there may be some difficulty in getting a whole lot of
precipitation. Forecast rain amounts are now in the tenth to
quarter inch range, although it`s possible some areas get none.
Weak instability and deep layer shear around 40 kt could
support a few thunderstorms however. Increased cloud cover will
likely knock temperatures down a little, but with enough sun,
eastern areas will still likely reach the mid 70s to near 80.
The front will push southward through the area Friday night,
ending the chance for rain. Lows will be in the 40s to near 50.-- End Changed Discussion --
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.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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The area will remain dry on Saturday. Highs will still average about
ten degrees above Mid-March norms with mid 60s for most.
Sunday likely starts dry, but a potent sub-522 dm trough is progged
to move through the area Sunday through Tuesday. A cold front will
move through Sunday night. This will bring rain showers to the
region. On the backside, mountain snow showers are evident across
most ensemble guidance Monday into Tuesday. There is a wave of
energy that could enhance snow showers late Monday night across the
Alleghenies, with rain elsewhere.
A more pronounced cooling trend ensues which comes with increasingly
gusty northwesterly winds (25-35 mph, higher in the mtns) amidst the
CAA. The true extent of the cold blast does not really take shape
until Tuesday as temperatures fall back into the mid/upper 40s.
Though the growing season has not officially started, any early
budding flowers/trees could succumb to the cold temperatures next
week with multiple days of sub-freezing nightly lows becoming
increasingly likely.-- End Changed Discussion --
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.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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VFR conditions will continue through Thursday. Winds will be light
and variable but generally between west and south. Only a few
periods of mid/high level clouds are expected.
By Friday afternoon, scattered showers along with a few
thunderstorms will be possible as a cold front approaches the
area. Winds shift from southerly to northwesterly and could be
briefly gusty. There`s also a chance of sub-VFR ceilings near
and behind the front.
Behind the front Saturday, conditions will dry out with winds out of
the WNW gusting to 15-20 kts. By Saturday afternoon/evening, the
winds will lessen and become more south of west. Southerly winds
continue ahead of a cold front Sunday. Rain showers are possible
along the front. Winds turn back to WNW behind the cold front Sunday
night into Monday and could gust to 20-25 kts.-- End Changed Discussion --
&&
.MARINE...
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No marine hazards are expected through the day on Thursday with
light westerly to southerly winds expected. By Thursday night,
a low pressure system will move into the Great Lakes. Southerly
winds may approach SCA criteria, but warm air over cool waters
may produce low level stability. That same theme will continue
into Friday. Showers and a few thunderstorms are possible Friday
afternoon and evening as a cold front pushes through.
Northwesterly winds may be near advisory levels behind the
front.
SCA may linger out of the NW across the southern waters Saturday
morning before diminishing out of the south through the afternoon.
Southerly channeling could result in marginal SCA conditions
Saturday night. Winds turn back out of the WNW behind the front
Sunday night into Monday resulting in renewed SCA conditions.-- End Changed Discussion --
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.FIRE WEATHER...
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Light winds are occurring today, with local terrain and marine
influences evident in directions, amidst a continued very warm
and dry airmass in place. Min RH in the 20 to 30 percent range
is occurring with deep mixing. High and mid-level clouds will
provide some shading before exiting this evening.
Thursday will be warmer still with only slight increases in Min RH
to 25 to 35 percent. Winds will become more southerly with
gusts increasing during the evening along the higher elevations.
A low pressure system will approach the area Friday and bring the
next chance of rain, although forecast amounts have been trending
downward.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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Tidal anomalies are on the increase with lighter winds in
place, and that upward trend will continue through the end of
the week as winds become more southerly Thursday. Some tidal
sites may exceed minor flood stage Thursday and (especially)
Friday mornings with the increased southerly flow ahead of the
next low pressure system. A wind shift Friday evening will end
this threat.-- End Changed Discussion --
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...ADS
NEAR TERM...ADS
SHORT TERM...ADS
LONG TERM...CPB
AVIATION...ADS/CPB
MARINE...ADS/CPB
FIRE WEATHER...ADS
TIDES/COASTAL FLOODING...ADS