Area Forecast Discussion Issued by NWS Sterling, VA
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000
FXUS61 KLWX 241844
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
244 PM EDT Sun Mar 24 2024
.SYNOPSIS...
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High pressure will gradually build into the region through
tonight and hold through the first half of the week. A weak
cold front will cross the area Thursday.-- End Changed Discussion --
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.NEAR TERM /THROUGH TONIGHT/...
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Continued sfc ridging/cool wedge anchored on a 1040+ mb high
pressure center over the center of Quebec will remain over the
area through the first half of the week. This will keep sfc
temps quite cool today and below normal through Tue. Winds will
gradually diminish through the day, but it will be quite cool
and brisk for late March standards despite full sunshine. Cold
tonight under very dry air mass and light winds. Lowered temps
below NBM guidance given favorable pattern for radiational
cooling. For those with vegetation interests, another hard
freeze is likely outside of the DC metro and southern Maryland. Would
not be surprised with the typical cooler valley locales being
in the upper teens to near 20F.-- End Changed Discussion --
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.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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Ridging will hold through at least Tue keeping fair weather
conditions. Some moisture return is expected Tue night which may
result in a few showers Tue night, but it`s likely that any
showers will hold off until Wednesday.
Have increased winds along/west of the Allegheny Front Monday
night into Tuesday morning where downslope winds are forecast to
gust to 30-40 kts. H85 winds are not at the best orientation for
most of the wind to make it to the sfc, but will continue to
monitor. Looks like the greatest threat is just west of the FA
at this time.-- End Changed Discussion --
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.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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Split flow persists across the country with a closed low pivoting
across southeastern Canada while a southern stream feature pushes
toward the Carolinas. Within the latter area of interest, models are
consistent in developing a wave of low pressure which is to
strengthen as it exits off the Atlantic coast. At this point, the
best chance for any rainfall would be east of the Blue Ridge,
particularly for those along and east of the I-95 corridor. The
associated shield of rainfall begins to exit into the Delmarva
Peninsula by Thursday night. In the wake, expect increasing
northwesterly winds as gradients tighten due to deepening low
pressure over the western Atlantic. Friday`s wind gusts could push
up to around 30 to 35 mph, locally a bit higher across the higher
elevations. Despite the frontal passage, a downsloping component to
the flow should offset the results of cold advection effects. To
finish out the work week, high temperatures should be seasonable,
generally into the mid 50s to low 60s (40s across the mountains).
Over the weekend, ensembles agree on a further warming trend as
heights build. A weak frontal zone approaches, but expect a mainly
dry weekend. Forecast winds shift to westerly with afternoon gusts
up to 15 to 20 mph, with 25 to 30 mph across the higher terrain.-- End Changed Discussion --
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.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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N winds gusting up to 20 kt will be main impact to terminals
this afternoon, gradually decreasing through the evening. Winds
become less than 10 kt tonight. P6SM SKC continuing.
Continued VFR conditions Monday with a light southeast wind
gusting to 5-10 kts.
With some precipitation impacting terminals on Thursday,
restrictions are possible at times, particularly for locations east
of the Blue Ridge. Expect dramatic improvements into Friday and the
weekend as VFR conditions are expected. The bigger story will be the
gusty northwesterly winds, particularly on Friday. Afternoon gusts
could approach 25 to 30 knots, before falling to around 15 to 20
knots on Saturday as winds turn westerly.-- End Changed Discussion --
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.MARINE...
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SCA conditions for all of Potomac and Chesapeake Bay south of
Bay Bridge through sunset. SCA conditions will persist into the
overnight across the southern Potomac and Chesapeake. Added back
in middle and northern Chesapeake for late in the overnight into
the first part of Monday AM as most guidance has a renewed puff
of wind moving over the waters through ~14Z.
Wind fields increase across the waterways during the second half of
Thursday. This is in response to a coastal low pressure system which
passes off to the southeast. Small Craft Advisories will likely be
needed by Thursday afternoon. Northerly winds increase in earnest
late Thursday with near gale force winds possible over the lower
waters. These gusty winds persist through Friday afternoon while
turning more northwesterly in nature. Although winds decrease a bit
toward Friday night, Small Craft Advisories may be needed into the
night.-- End Changed Discussion --
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.FIRE WEATHER...
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Dry conditions are expected today as high pressure builds in from
the west, but temperatures will be below normal with gusty winds.
The high will remain to the north Monday into Tuesday as
temperatures warm closer to normal. A slow moving front will bring
increasing chances of rain showers Wednesday into Thursday.
Recent wetting rains should keep fuel moistures somewhat elevated
for the next few days, but wind gusts of 20 to 30 mph out of the
north are likely today, turning more northeast during the
afternoon. Lighter winds are expected Monday through Wednesday,
although higher ridges above 2000 feet could start seeing some
stronger gusts greater than 20-35 mph Monday night.
Relative humidity values will drop to 25 to 35 percent this
afternoon. RH is expected to recover to 60 to 80 percent tonight,
and 70 to 90 percent Monday night, with minimum afternoon values
of 25 to 35 percent Monday afternoon, and 35 to 55 percent Tuesday
afternoon.
Mixing and smoke dispersion should be fair to excellent this
afternoon, becoming poor to fair with lighter winds tonight through
Monday night. Improving smoke dispersion is likely on Tuesday..-- End Changed Discussion --
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.TIDES/COASTAL FLOODING...
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Northerly flow started to let up a bit and turn more northeasterly
as of early this afternoon. After dropping to around or just below 1
ft MLLW on the northern part of the Chesapeake Bay, tide levels have
already begun to show a bit of a rebound heading into mid afternoon.
Low water issues may persist in the far northern bay into early this
evening, but should abate shortly thereafter.
The tidal rebound (snap-back) was outpacing ETSS a bit, but was not
nearly as pronounced as the very aggressive CBOFS (more in line with
ESTOFS/P-ETSS/SFAS). Anomalies were running 1-1.5 ft above normal
over the lower part of the bay, and this excess water should slosh
north over the next 12-24 hours. This would result in near minor
flooding of vulnerable shoreline as early as Monday afternoon. There
are hints of a period of enhanced northeasterly winds tonight, and
this could cause anomalies to rise a bit quicker than currently
forecast if it`s a little stronger or longer than anticipated.
The east to northeasterly flow will persist through Tuesday, piling
water into the mouth of the Chesapeake Bay. Anomalies are expected
to continue to rise through Tuesday, then surge more readily Tuesday
night into Wednesday as flow turns southeasterly to southerly. This
should push anomalies into the 2-2.5 ft range, and cause near
moderate tidal flooding for vulnerable shoreline locales; widespread
minor flooding is most likely elsewhere through Wednesday night.
There is uncertainty in the exact timing of a wind shift following
a frontal system/area of low pressure late Wednesday night into
Thursday, but flow is expected to eventually turn offshore causing a
notable decrease in tide levels by late Thursday into Friday.-- End Changed Discussion --
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.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from midnight tonight to 11 AM EDT Monday
for ANZ531>533-539>541.
Small Craft Advisory until 6 PM EDT this evening for ANZ532-
533-535-536-540>542.
Small Craft Advisory until 11 AM EDT Monday for ANZ534-537-543.-- End Changed Discussion --
&&
$$
SYNOPSIS...LFR
NEAR TERM...CPB
SHORT TERM...CPB
LONG TERM...BRO
AVIATION...BRO/CPB
MARINE...BRO/CPB
FIRE WEATHER...CPB
TIDES/COASTAL FLOODING...DHOF