Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 180741

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
341 AM EDT Tue Oct 18 2016

High pressure in the western Atlantic will remain in place for
the next several days. A cold front will slide southward toward
the area Wednesday before lifting back north Thursday. Another,
stronger cold front will cross the region Friday. High pressure
will return for the weekend.


A large ridge of high pressure, both aloft and at the surface,
centered to the south of the region will be in control of the
weather today. Once patchy fog lifts early this morning, mostly
sunny skies and very warm temperatures will be the theme of the
day. Highs will top out in the mid to upper 80s and be on the
order of 15-20 degrees above climatological normals. Records at
all three major climate sites will be in jeopardy (see climate
section below).


Another mostly clear night is in store for tonight, along with
some patchy fog, similar to previous nights. Temperatures remain
very mild again with lows in the low to mid 60s.

A weak boundary will then try to push southeastward towards the
region Wednesday and Wednesday night before lifting back northward
into Thursday. There are still some discrepancies as to the
southern extent of its progression, but latest trends indicate
that it will likely push southward enough to bring some clouds
later Wednesday, Wednesday night, and into Thursday morning, along
with the potential for some isolated/scattered rain showers.

Very warm temperatures will continue Wednesday with record or
near-record warmth. High temperatures will rise into the 80s
area-wide again, with lows Wednesday night in the 50s/60s.
Abnormally warm weather persists into Thursday, although the
temperature forecast is a little trickier and dependent on how
quickly the boundary and any remaining clouds lift out. Will show
temperatures in the upper 70s in northern Maryland to mid 80s in
central Virginia.

Potent upper level trough and frontal system then approaches
Thursday night with increasing chances for rain showers from west
to east. Lows still mild out ahead of the front, in the 50s to
low 60s.


A potent cold front will pass through the region Friday and an
upper-level trough will build overhead behind the boundary for
Friday night. Showers are possible with the frontal passage Friday
but much cooler and drier air is likely to move in with a
northwest flow behind the boundary Friday night.

High pressure will build overhead for the weekend...bringing dry
and seasonably cool conditions. A reinforcing cold front will pass
through Sunday night into Monday and high pressure will return
for later Monday. Little moisture will be associated with the
boundary so conditions should remain dry.


Patchy fog with areas of MVFR expected early this morning, mainly
IAD/BWI/CHO/MRB. There may also be a brief period of IFR.
Conditions improve shortly after sunrise with VFR expected area-
wide with a few high cirrus as well as a few fair weather cumulus
this afternoon. Winds light and variable early this morning become
south/southwest 5-10 knots this afternoon.

Mainly VFR expected tonight and Wednesday, however there will
likely be some patchy fog around again overnight with reductions
to MVFR/IFR possible.

May be some lower ceilings Wednesday night into Thursday morning
with a weak frontal boundary near the area. Rain shower chances
then increase Thursday night along with the possibility for some
reductions in ceilings/visibilities as a cold front nears the

A cold front will pass through the terminals Friday. Showers and
subvfr conditions are possible. A wind shift to the northwest is
expected behind the boundary.

VFR conditions are expected for the weekend behind the boundary as
high pressure builds toward the area.


Winds will be primarily out of the south and sub-SCA through
Thursday. May see a few gusts approach 20 knots later this
afternoon, but confidence too low to raise a Small Craft Advisory.

Winds increase a bit out of the south Thursday night ahead of an
approaching frontal system and winds may approach SCA conditions.

A cold front will pass through the waters Friday. Gusty northwest
winds are expected behind the front through Saturday night. A
small craft advisory will be needed and gale warnings may be
needed for portions of the waters during this time.

High pressure will build toward the waters Sunday and a
reinforcing cold front will pass through Sunday night into Monday.
A small craft advisory will likely be needed for the waters during
this time.


A south to southwest flow will continue over the waters through
Wednesday night. Southerly winds are most likely Thursday into
Friday ahead of a cold front. Elevated water levels are expected
during this time. Minor tidal flooding is possible for sensitive
areas...particularly during the high tide cycle during the evening
into the overnight hours where that will be the higher of the two.

A potent offshore flow will develop behind a cold front later
Friday through the weekend. Blowout tides are possible during this


Below is a list of record daily warm temperatures for
October 18th through 20th. Washington-Dulles broke the record high
temperature on October 17th. The high was 84 degrees breaking the
old record of 83 degrees set in 1963.

Record daily high temperatures
Site    10/18       10/19       10/20
DCA    85 (1938)*  88 (1938)   86 (1969)
BWI    82 (1945)*  82 (1947)*  87 (1969)
IAD    82 (2007)*  83 (1991)*  83 (1969)
*also occurred in previous years

Record daily warm low temperatures
Site  10/18       10/19       10/20
DCA   68 (1947)*  65 (1905)   64 (1885)*
BWI   69 (1928)   67 (1905)   65 (1910)
IAD   60 (1968)   60 (2011)   59 (1993)
*also occurred in previous years




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