Area Forecast Discussion Issued by NWS Sterling, VA
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000
FXUS61 KLWX 131403
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1003 AM EDT Wed Mar 13 2024
.SYNOPSIS...
Surface high pressure will continue to influence the Mid-Atlantic
region over the next few days with well above normal temperatures
and mostly dry conditions. A low pressure system will approach the
area Friday, bringing increased chances for rain. Another low
pressure system may impact the region Sunday into Monday.
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.NEAR TERM /THROUGH TONIGHT/...
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The center of surface high pressure extends eastward from
Florida this morning. A weaker gradient will support much less
wind today, generally 5-10 mph. A shortwave trough is
approaching from the Ohio Valley, resulting in a good deal of
mid and high level cloudiness. Have lowered high temperatures by
a couple degrees since sunshine will be filtered and lighter
winds may pose minor limitations on boundary layer mixing
compared to yesterday. However, this is still on the warm side
of guidance, with most areas in the lower to mid 70s and 60s in
the higher elevations.
Skies clear out again tonight as the shortwave moves further away.
Overnight lows will be in the 40s for most of the area with light
winds continuing.-- End Changed Discussion --
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.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Another mostly dry day is expected on Thursday with a mix of sun and
clouds throughout the day. Dewpoints begin to rise slightly for the
afternoon so do expect temperatures to favor a slight increase
compared to today with mid to upper 70s expected across the lower
elevations. Would not be surprised to see a few areas across central
VA reach 80 degrees.
The main exception for potential precipitation would be across the
Allegheny Front as the low pressure system gets closer to the Ohio
Valley later in the day on Thursday. The associated warm front will
likely extended across PA by Thursday night, leading to well above
average low temperatures for the overnight hours. Most areas will
likely only drop down into the mid to upper 50s. Clouds are expected
to become more abundant overnight as a more moist airmass begins to
invade the Mid-Atlantic.
The low pressure system will begin bringing impacts to the area on
Friday. First, the area will likely remain in the warm sector and
thus allow highs for the day to be similar to Thursday with mid to
upper 70s expected across much of the area with 60s in the
mountains. Most of the area will be mostly dry early Friday before
the main precipitation shield moves in for the afternoon/evening
hours. Some guidance has a few hundred joules of SBCAPE across the
area, yielding the potential for a few thunderstorms on Friday. The
system continues to look progressive in nature so QPF totals remain
in the less than a quarter inch range, with the highest values the
further west you go. Most of the precipitation should be out in the
late overnight hours where lows will be in the upper 30s out west
and upper 40s to low 50s closer to the waters with decreasing
clouds.
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.LONG TERM /SATURDAY THROUGH TUESDAY/...
On the synoptic scale, a rex block persists across western
North America while an amplified northern stream anchors much of
the central to eastern U.S. Subtropical ridging becomes
suppressed and mainly focuses over Florida into the Caribbean.
Within this northern stream flow, one such wave will have
already exited the Atlantic coast. In its wake, temperatures are
forecast to cool some over the weekend after a lengthy period
of mild weather.
A much stronger longwave trough enters the picture late in the
weekend and into early next week. Comprised of sub-522-dm mid-level
heights near Hudson Bay, a plunge of colder air works its way into
the Great Lakes region on Sunday. The associated cold front races
eastward reaching the I-95 corridor by late Sunday. Some shower
activity is possible as this system presses through. In its wake,
the true surge of colder air enters the Mid-Atlantic region with
falling temperatures to start off the work week. After a weekend
with high temperatures mainly in the 60s, readings return to near to
below normal.
In addition to the cooler weather, gusty west to northwesterly winds
will overspread the area. For both Monday and Tuesday, wind gusts
could push up to 25 to 35 mph, locally a bit higher over mountain
locales. This cold advection pattern is forecast to lower
temperatures into the mid/upper 40s by Tuesday, with upper 20s to
30s over the higher terrain. Additionally, upslope enhanced snow
showers are possible starting as early as late Sunday night. This
continues the following couple of days given the cyclonic flow aloft.
Downstream locations likely stay dry in this regime.
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.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will continue through Thursday. Winds will be light
out of the west today and south or southwest Thursday.
Only a few periods of mid/high level clouds are expected. By Friday,
scattered showers and thunderstorms will be possible, especially for
the afternoon and evening hours. Brief sub-VFR conditions will be
possible at times on Friday.
For the weekend, expect mainly VFR conditions at the area TAF sites.
A strong cold front does enter the equation Sunday evening and into
the night. Some showers may accompany this system with brief
restrictions possible. Otherwise, expect a multitude of wind shifts
over the weekend. Initial northwesterly flow turns more variable the
second half of Saturday. This eventually leads to a southerly flow
regime by late Saturday before the next cold front brings a return
to west-northwesterlies by Sunday afternoon/evening. Some increase
in gusts are possible as this front pushes through.
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.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 begin approaching the Mid-Atlantic
and may bring SCA winds to the waters. Showers and isolated
thunderstorms become possible during the day on Friday, an SMW
is possible. Additionally, winds likely pick back up post-
frontally Friday night and will likely warrant a SCA for most of
the waters.
Marine winds largely stay below Small Craft Advisory levels on
Saturday. With a shift to southerlies, some channeling effects over
the southern waters could near 18 to 20 knots on Saturday night. A
strong cold front pushes through Sunday evening with some small
craft potential late Sunday night. A better chance for such
occurrences looms thereafter.-- End Changed Discussion --
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.FIRE WEATHER...
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Light west to southwest winds are expected today (gusts to 20
mph possible on the ridges) with a continued very warm and dry
airmass in place. Latest adjustment to temperatures and dew
points results in another afternoon of Min RH in the 20 to 30
percent range. High and mid-level clouds will provide some
shading today however. Thursday will be warmer still but with
further increases in RH with winds becoming southerly. A low
pressure system will approach the area Friday and bring the next
chance of rain.-- 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. Some tidal sites may near minor flood stage Thursday
and Friday as winds turn southerly ahead of the next low
pressure system.-- End Changed Discussion --
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...ADM
NEAR TERM...ADS/ADM
SHORT TERM...ADM
LONG TERM...BRO
AVIATION...BRO/ADM
MARINE...BRO/ADM
FIRE WEATHER...ADS
TIDES/COASTAL FLOODING...ADS