Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 140759
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Sat Oct 14 2017

.SYNOPSIS...High pressure over the area will weaken rapidly through
Sunday. A cold front will push into the Mid Atlantic Sunday
night followed by a return to high pressure early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...Widespread low clouds cover much
of the fcst area except over Pendleton county with areas of
drizzle along and east of I-95 and patchy dense fog where skies
have cleared east of the Blue Ridge. These will gradually mix
out through the day with a pleasant Sat with temps rising into
the mid 70s. Areas of dense fog may form again late tonight
under clear skies and light winds and dewpoints remain high.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...Warm day on Sun
under strengthening southwest flow ahead of a cold front
especially east of the Blue Ridge where clouds will be less and
showers take longer to arrive. Showers appear likely everywhere
during the evening Sun as cold front moves through the area.
Gusty winds up to 30 mph will accompany the front as models
show decent pressure rises. Showers will linger over southern MD
into Mon morning before pushing south by midday. Rapid clearing
expected Mon as drier air moves in behind fropa and as high
pressure builds in. Taste of fall Tue morning with lows dropping
into the 40s and even 30s west.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...

A shortwave trough will be moving off the coast Tuesday morning
while surface high pressure builds eastward from the Ohio Valley.
That high pressure system will be the story of the extended forecast
period as it more or less remains parked over the region. The
ensemble suite of guidance is in good agreement with the overall
pattern. Aloft, flow will be progressive and wavy through midweek,
with east coast ridging becoming amplified by the end of the week as
a deep trough moves onto the west coast.

Looking at the BUFKIT overview cross-section, there is a stark lack
of moisture in the atmosphere for much of the week. It will remain
cool through mid-week, but near normal. We`ll have to keep an eye on
frost/freeze potential (mostly western valleys at this point)
Tuesday and Wednesday mornings. Highs will remain in the 60s again
on Tuesday despite sunshine. The airmass will modify as the week
progresses with temperatures rising back above normal, although 80s
look unlikely at this point.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...

Widespread IFR even LIFR conditions this morning with cigs
improving later today. Patchy dense fog possible again tonight.
Cdfnt will be crossing the area early Sun evening with showers
likely. Gusty NW winds behind fropa up to 25 kt Sun night.

No significant weather expected Tuesday and Wednesday with high
pressure.

&&

.MARINE...

Light winds today, but winds strengthen Sun and especially Sun
night with fropa. Gusts up to 25 kt expected on the waters. SCA
will be raised later this morning.

Small Craft Advisory conditions in northwest flow may linger through
Tuesday morning on portions of waters. Winds will then subside
through mid-week as high pressure builds over the area.

&&

.TIDES/COASTAL FLOODING...Tidal anomalies have come down
significantly since yesterday, but water levels remain elevated
on the Potomac River. Made significant changes to headlines to
drop them at most places except along the Potomac River.

&&

.CLIMATE...

A surge of warm air is expected Sunday ahead of the cold front.
We are not currently forecasting records, but we are expecting
temps to be close.

     Warm Temperature Records for October 15 (Sunday)...
     High             Warm Low
DCA  87 (1975)        67 (2008)
BWI  86 (1989, 1975)  66 (1941)
IAD  88 (1989) 64 (1985)

&&

.EQUIPMENT...

The NWS 88D Sterling radar (KLWX) will be down during the day
from 7 AM through at least 5 PM through Saturday. This is for
nationally scheduled maintenance on the radome. Surrounding 88D
radars as well as FAA terminal radars will be operational during
this downtime.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Advisory until 7 AM EDT this morning for DCZ001.
MD...Coastal Flood Advisory until 5 AM EDT early this morning for
     MDZ014.
     Coastal Flood Advisory from 9 AM this morning to midnight EDT
     tonight for MDZ017.
VA...Coastal Flood Advisory until 7 AM EDT this morning for VAZ054.
WV...None.
MARINE...None.

&&

$$
SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...ADS
AVIATION...ADS/LFR
MARINE...ADS/LFR
TIDES/COASTAL FLOODING...LFR
CLIMATE...LWX
EQUIPMENT...LWX



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