Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 231450
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1050 AM EDT Sun Apr 23 2017

.SYNOPSIS...
A cold front is stalled over the Carolinas today. Low pressure
along the front will track toward the Mid-Atlantic Coast Monday
and it will remain nearly stationary through Tuesday before
finally weakening and moving off to the north and east on
Wednesday. A cold front will approach the area Thursday but it
will stall out nearby or just to our north for Friday. The cold
front may move into the area next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Persistent northerly flow from elongated ridge over the eastern
Great Lakes has shunted frontal boundary and deeper moisture
south of much of the area this morning. A few showers do
remain across central Virginia, but most areas are rain-free.

As low pressure system moves through the southeastern US during
the day today, additional rain will break out across portions
of the lower Appalachians and try to push northeastward.
However, low level dry air will continue filtering southward on
northeasterly flow. This will keep most areas dry through much
of today. The exception will be parts of central VA where rain
will gradually expand through the day, reaching into portions of
southern Maryland towards the evening hours.

Otherwise, abundant sun across the northern half of the CWA at
present will cloud back up as dense high clouds move back
overhead from the southwest. High temperatures will range from
the mid/upper 50s in central VA to low 60s in northern areas.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Low pressure system will work towards the SE US coast tonight
and move to a position near the NC/SC border on Monday. Rain
will continue to overspread the region from south to north
tonight and persist through Monday with strong moisture
advection. Periods of rain will continue through Monday night,
although intensity likely to experience a downtrend later Monday
and Monday night as forcing lessens.

As the low pressure system then slowly trudges up the Mid-
Atlantic coastline, to a position near the Outer Banks/Norfolk
by later Tuesday, periods of rain will continue, with an uptick
in intensity/coverage likely again. Low pressure will slowly
fill and weaken Tuesday night with rain tapering off.

Additional rain amounts from this morning through Tuesday night
expected to range on average from 1-2", with somewhat less in
northern/western areas to locally 2-3" south, especially along
the eastern facing slopes in Nelson County and along the Blue
Ridge.

Temperatures during this time period will see limited diurnal
change with solid overcast and periods of rain. Highs Monday
will hold in the low/mid 50s, possibly nearing 60F on Tuesday.
Lows tonight/Mon night from the mid 40s to low 50s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Cutoff low pressure along the Mid-Atlantic Coast Wednesday
morning will finally get drawn into the jet stream and move off
to our north and east. Morning clouds and perhaps even a light
rain should give way to some sunshine Wednesday afternoon.
However...clouds may be stubborn to give way to sunshine across
eastern areas depending on how quick the low moves away from the
area. Noticeably warmer conditions are expected
Wednesday...especially west of the Blue Ridge Mountains where
confidence is higher in more sunshine.

High pressure will build over the Atlantic for Wednesday night
through Friday. A cold front to our west will approach our area
Thursday...but it will likely stall out nearby or just to our
north as it runs into the blocking high over the Atlantic.
Therefore...much warmer and more humid conditions are likely
during this time. A few showers and thunderstorms are
possible...but coverage may be isolated or scattered due to most
of the mid and upper-level forcing remaining well off to the
north and west. A backdoor cold front may impact the area next
weekend.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Mainly VFR is expected today with thickening and lowering
high/mid clouds. A few showers will move near CHO this morning,
with rain then affecting the site by the afternoon, before
gradually spreading northward across all sites this evening and
tonight. Conditions will deteriorate as the rain/stratus
overspread with MVFR/IFR developing later tonight and on Monday.
Rain/stratus and associated reductions expected to continue
through at least Tuesday, possibly Tuesday night. Winds will be
out of the northeast through the period.

Low clouds may impact the terminals Wednesday morning.
Conditions should gradually improve later Wednesday. High
pressure over the Atlantic will cause southerly winds and mainly
VFR conditions for Wednesday night and Thursday. A few showers
and thunderstorms are possible Thursday.

&&

.MARINE...
SCA conditions have gradually tapered this morning, with SCA-
winds confined to only portions of the central Chesapeake this
afternoon. This will however be a short-lived break as
northeasterly winds re-intensify tonight and continue through
Tuesday night as coastal low intensifies and slowly moves up the
east coast.

Low pressure will move away from the waters Wednesday. High
pressure over the Atlantic will cause a southerly flow for
Wednesday night through Friday. A Small Craft Advisory may be
needed for portions of the waters during this time. A few
showers and thunderstorms are possible Thursday and Friday...but
coverage may be isolated or scattered since forcing will be
weak.

&&

.TIDES/COASTAL FLOODING...
A persistent onshore flow will continue over the waters through
Tuesday. Elevated water levels are expected during this time.
Most areas should remain below minor flooding thresholds through
the high tide cycle this afternoon, except Straits Point, where
an advisory is now in effect.

The onshore flow will strengthen a bit for tonight through
Tuesday. Minor flooding is possible near times of high tide. The
flow should gradually turn north Tuesday night into Wednesday as
the low moves away from the area. Water levels should decrease
during this time.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 2 PM EDT this afternoon for
     MDZ017.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 6 AM Monday to 6 AM EDT Tuesday for
     ANZ530>532-535-536-538>542.
     Small Craft Advisory until 6 AM EDT Tuesday for ANZ534-543.
     Small Craft Advisory from 6 PM this evening to 6 AM EDT
     Tuesday for ANZ533-537.

&&

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



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