Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 141500
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1000 AM EST Thu Dec 14 2017

.SYNOPSIS...
High pressure will build overhead through tonight. Low pressure
will develop along the North Carolina coast Friday and move out
to sea Friday night. High pressure will return for Saturday
before weak low pressure impacts the area early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Cold front is currently crossing the region with clouds, a
burst of gusty winds, and perhaps a few flurries/sprinkles. High
pressure will then build overhead later today, with lower
clouds scattering out before high clouds increase again towards
evening. Max temps will range from the 30s in northern and
western areas to the mid/upper 40s in southern Maryland and
parts of central VA.

A Wind Advisory remains in effect through Noon for the higher
elevations of the Blue Ridge and Potomac/Allegheny Highlands.
Gusts up to 50 mph are expected above 2000 feet. The winds will
then subside heading into the afternoon. Elsewhere...gusts
to 30-35 mph are expected late this morning into this
afternoon.

A jetmax will develop tonight in the westerly flow aloft and our
region will be in the right entrance region...which will cause
an increase of high and mid-level clouds but it should remain
dry. Surface high pressure will build overhead. Light winds and
dry air will allow for some radiational cooling. Min temps are
forecast to be in the lower to middle 20s for most areas...but
it could even be several degrees colder in rural and valley
areas. Did not account for this in the forecast at this time due
to the increasing high/mid-level clouds.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
High pressure will move off to the east Friday morning and an
upper-level trough axis will swing through the area late Friday
into Friday evening. Northern stream energy is not expected to
phase with the southern stream energy. Therefore...the coastal
low that develops should be weak and it should move out to sea.
This means that there is a much higher likelihood of dry
conditions across our area during this time. Did still allow for
the slight chance of snow showers across eastern areas...closer
to the coastal low but even for these areas confidence of any
snow is low at this time.

High pressure will build overhead later Friday night...causing
dry and seasonably chilly conditions.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
High pressure will remain over the area Saturday into Saturday
night...bringing more dry and seasonably chilly conditions.

Surface high pressure will reside along the Carolina coast Sunday
morning, generating a light southerly flow across the region as
it migrates eastward during the day. This will allow
temperatures to crack the 50 degree mark, or about 5 degrees
above normal for the middle of December. A shortwave trough will
cross the area Sunday night in to Monday morning, bringing the
chance for rain showers with temperatures at the surface and
aloft above freezing. Locations near the Mason Dixon could
possibly see a rain/snow mix, but with marginal temperatures at
the surface and 850mb, do not expect any snow accumulation at
this time.

With multiple pieces of mid-level energy traversing the region
Monday into Tuesday, slight chance pops will be retained in our
gridded forecast. While temperatures continue their above normal
trend with a mild west southwest flow aloft, precipitation will
remain of the liquid variety. A cold front looks progged to press
through the area late Tuesday or Tuesday evening, dropping
temperatures back to more seasonable levels. High pressure
builds in from the southwest Wednesday through Thursday,
keeping conditions dry and temperatures slightly above normal.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
VFR conditions are expected through Saturday night. Gusty
northwest winds up to 25-30 knots are expected through today,
diminishing by sunset. A period of light snow or snow showers
are still possible across the eastern terminals later Friday
into Friday evening...but confidence is low at this time and
there is much higher likelihood that it will remain dry.

With high pressure in control to our south, VFR conditions will
prevail during the day on Sunday. A weak shortwave trough will
cross the area Sunday evening and into Monday, bringing the
chance for showers at the terminals with the potential for sub-
VFR conditions. Winds will remain light out of the south Sunday,
veering out of the southwest on Monday.

&&

.MARINE...
A weak cold front will pass through the waters this morning.
Gusty northwest winds are expected through the day, mainly in
the 20 to 30 knot range, however a Gale Warning does remain in
effect until Noon for some gusts around 35 knots across the
Chesapeake Bay from Drum Point to Smith Point. Isolated gusts
around 35 knots are possible with the cold front this
morning...but winds will be brief and confidence is too low for
a Gale Warning at this time.

A Small Craft Advisory continues for most of the Bay and lower
Tidal Potomac River tonight. High pressure will build overhead
for later tonight into Friday. Low pressure will develop and
move out to sea later Friday. Gusty winds are possible behind
the front Friday night through Saturday.

High pressure will reside to the south southeast Sunday into
Monday, resulting in light southerly winds across the waters as
a weak system crosses the area. Winds look to remain below
advisory criteria through Monday night.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Wind Advisory until noon EST today for MDZ501.
VA...Wind Advisory until noon EST today for VAZ025-026-503-504-507-
     508.
WV...Wind Advisory until noon EST today for WVZ501>503-505-506.
MARINE...Small Craft Advisory until midnight EST tonight for ANZ531>533-
     537-539>541.
     Small Craft Advisory until 6 PM EST this evening for ANZ530-
     535-536-538-542.
     Small Craft Advisory until midnight EST tonight for ANZ534-543.
     Gale Warning until noon EST today for ANZ534-543.

&&

$$
SYNOPSIS...BJL/MM
NEAR TERM...BJL/MM
SHORT TERM...BJL
LONG TERM...BKF
AVIATION...BJL/MM/BKF
MARINE...BJL/MM/BKF



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