Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 251929
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
229 PM EST Fri Nov 25 2016

.SYNOPSIS...
Low pressure will track across Virginia tonight and move out to
sea early Saturday. High pressure builds over the region for the
weekend into early next week before another storm system
approaches for the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The Mid-Atlantic region is mid transition this afternoon as low
pressure develops to our south and high pressure approaches the
region from the west. Light, onshore flow will come to an end by
this evening and northwesterly dry conditions will move into the
region from west to east by late tonight. In the meantime...low
clouds east of the Blue Ridge will shift eastward while clearing
occurs across much of the Mid- Atlantic region with the exception
of the Allegheny Front. Can not rule out a shower east of the I-95
corridor this afternoon however coverage will be isolated and
amounts light.

Temperatures will drop into the 30s/L40s and 20s in the mountains
tonight. NW winds will increase as high pressure moves eastward
and gusts of 15-20 mph are possible overnight. A shallow layer of
moisture is expected across the Allegheny Front tonight. Fog and
drizzle are expected and as temperatures drop to
freezing...freezing drizzle is possible. There is uncertainty in
the depth of the moisture layer at the surface and therefore
extent of freezing drizzle is unknown. If the moisture layer
becomes deeper snow showers may actually begin late tonight. Due
to the uncertainty...no ice or snow accumulation is expected at
this time and no advisory was issued. Evening shift will revisit
the potential for any accumulation.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A shortwave trough will cross the region Saturday morning and any
freezing drizzle will likely transition to snow showers Saturday
morning. Little to no accumulation is expected. NW winds will
increase Saturday and 10-15 mph with gusts up to 25 mph.
Temperatures will range from the 40s north-west of the metros and
50s elsewhere. Snow showers will taper off by Saturday evening.

High pressure continues to move eastward and northwest winds will
continue Saturday night through Sunday. High pressure moves
overhead Sunday night and temperatures will drop into the 20s/L30s
Sunday night.


&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
High pressure along the East Coast will move offshore Monday. Also,
a strong storm system over the Upper Midwest U.S. will strengthen.
The difference in pressure between the high and the storm system
will provide an increased southerly flow late Monday through
Tuesday.

There is a chance for a few rain showers along a warm front
Monday night. The likelihood of rain showers will become imminent
Tuesday as a cold front approaches the region.

There could be brief break in the rainfall activity Tuesday night
into Wednesday morning as a weak area of high pressure slides east
across the Mason-Dixon Line.

A second storm system could develop over the Southern Appalachians
along the first storm`s slow-moving cold front Wednesday morning.
This next storm system could ride northeast along the eastern slopes
of the Appalachian Mountains. Additional rain showers may develop
and overspread the region through the day Wednesday into Wednesday
evening.

High pressure could build in behind the departing storm system
and bring drier and cooler air into the region late Wednesday
night into Thursday.

An upper level trough of low pressure is expected to sag southward
into the region from the Eastern Great Lakes Thursday night. There
may not be a lot of moisture available to fuel any showers with the
trough. Additional cloud cover may be the only story here.

High pressure is expected to build in behind the trough of low
pressure Friday.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
Cigs will improve today and VFR conditions are expected by this
evening. MVFR cigs still possible at IAD/DCA this afternoon. A
front will push through this evening, bringing an onset of
northwesterly winds. NW winds will continue through Sunday, with
the strongest period during the daytime Saturday (G20-25 kt). Any
clouds should be VFR.

Vfr conditions expected Monday. Mvfr conditions possible at any one
of the terminals with a few rain showers in the area. Winds southeast
around 5 knots Monday. Winds southeast 5 to 10 knots Monday night.

&&

.MARINE...
Light and variable winds today with a weak pressure pattern
(perhaps a northerly component). A cold front will then cross the
area this evening, with NW flow increasing. Based on forecast
soundings, am seeing a potential for 20-25 kt gusts on all waters
after 1 AM, and have thus started a SCA at that time. As higher
resolution data become available, the start time may be refined.
SCA conditions continue through the day Saturday. Winds may lessen
some by Saturday evening, but the more open waters may require a
SCA into Sunday. Winds become light by Sunday night as high
pressure builds overhead.

No marine hazards expected Monday and Monday night. Winds
southeast 5 to 10 knots Monday. Winds southeast 10 to 15 knots
Monday night.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 1 AM Saturday to 6 AM EST Sunday for
     ANZ530>534-537>543.
     Small Craft Advisory from 1 AM to 6 PM EST Saturday for ANZ535-
     536.

&&

$$
SYNOPSIS...HSK
NEAR TERM...HSK
SHORT TERM...HSK
LONG TERM...KLW
AVIATION...HSK/KLW
MARINE...HSK/KLW



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