Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 231410
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1010 AM EDT Wed Aug 23 2017

.SYNOPSIS...
A cold front will drop southeastward across the mid-Atlantic region
today, before stalling over southeast Virginia tonight. Upper level
energy will sweep southeastward tomorrow and push the front offshore
tomorrow night. High pressure will quickly follow tomorrow night and
persist right on into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Northwesterly winds in the boundary layer suggest the surface
front is through the area, although the airmass boundary (lower
dew points) runs from north central Maryland to the Virginia
Highlands. The mid level boundary remains overhead though,
resulting in mostly cloudy skies and some light showers and
sprinkles across central Virginia. HRRR has been over-developing
this activity, so only expect some light showers across southern
portions of the CWA through midday.

Instability is expected to be confined from Charlottesville to
southern Maryland this afternoon. Even so, the better forcing
should be south of the area and a mid level stable layer will
likely limit any updrafts. Have maintained chance POPs for this
area.

As we proceed into the overnight hours, clouds and precipitation
chances decrease and slide to the east. Temperatures will be
nearly 10 degrees cooler than yesterday across much of our
region with humidity values on the downward trend as well. High
temperatures will be mainly in the middle 80s with low
temperatures tonight dropping down into the lower 60s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Thursday will consist of two factors of weather. One of them an
upper level disturbance dropping out of the Lower Great Lakes region
into the mid-Atlantic region. This disturbance will help to kick the
stalled front over southeast Virginia out to sea and could produce a
couple of sprinkles in the northern Potomac Highlands. The other
factor will be a firm ridge of high pressure that will build in from
the northwest about the same time as the disturbance moves
southeastward. The high pressure will strengthen behind the passing
disturbance to give us a couple of periods of dry conditions and
comfortable temperatures from Thursday right through Friday night.
High temperatures Thursday and Friday will be near 80 with low
temperatures Thursday night and Friday in the upper 50s to near
60.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The weekend forecast will still be dictated by high pressure over
northern New England. As has been advertised for a couple of days,
temperatures/humidity levels will be almost fall-like. The only
precipitation potential will come over the mountains at the end of
the day...and that would be limited to a stray shower.

Little will change for early next week, other than the center of the
high will move offshore. That could lead to a bit more moisture
flowing onshore, which may enhance diurnal/terrain showers.
We`re still talking about a small chance, with isolated to perhaps
at worst scattered coverage. And since water temperatures are in the
upper 70s, forecast air temperatures wouldn`t change much.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions expected at all terminals through Friday night. A
shower or thunderstorm could develop in the vicinity of CHO
near a stalled front through mid afternoon or so, but the chance
for impacts is low. Winds have become northwest at 5 to 10
knots behind the front. Winds will be generally northwest to
north 5 to 10 knots tonight through Friday night with typical
diurnal fluctuations each afternoon.

VFR conditions anticipated this weekend under high pressure.

&&

.MARINE...
North to northwest winds today should remain below SCA criteria.
A thunderstorm may affect the waters near southern Maryland this
afternoon, but think the opportunity for strong storms will be
farther to the south. Small craft advisories may be needed
Thursday with diurnal heating during the day and cool advection
aloft. No marine hazards expected Thursday night through Friday
night.

Winds this weekend should be light (at or below 10 kt) under the
influence of high pressure.

&&

.TIDES/COASTAL FLOODING...
Anomalies are falling now and should not pose a problem over the
next few days with continued north/northwest flow. No flooding
is forecast.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$
SYNOPSIS...KLW
NEAR TERM...ADS/KLW
SHORT TERM...KLW
LONG TERM...HTS
AVIATION...ADS/HTS/KLW
MARINE...ADS/HTS/KLW
TIDES/COASTAL FLOODING...ADS



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