Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 152123

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
523 PM EDT Sat Oct 15 2016

High pressure over New England will shift southward Sunday into
Monday and remain to our south through the middle of next week. A
cold front may approach the Mid-Atlantic region late next
Thursday into Friday.


Pleasant weather continues this afternoon...with high temperatures
near 70 F, sunny skies, and relatively light winds.

The one exception will be across eastern West Virginia...where most
guidance continues to indicate the possibility of a few afternoon
showers in response to enhanced mass/moisture convergence over that
area. This seems reasonable as visible satellite imagery is already
showing an agitated cu field over that area. Any showers that do
develop would dissipate by early evening.

No frost concerns lows remain in the upper 40s to low
50s across the entire area.


Quiet weather will continue through high pressure over
New England shifts southward and hangs up to our south. This will
promote continued WAA in S/SW flow...with temperatures/dewpoints
rising each day. By Monday highs expected to be near 80 F...and with
elevated dewpoints in the L/M 60s it will feel slightly muggy.


Unseasonably strong ridging will persist south of the area through
the middle part of the week. Near record warmth is possible during
this time (see Climate Section below). Meanwhile, a weak and
moisture-starved front will remain stalled near or just north of the

Most models agree with the idea of an amplifying pattern by late
next week, but differ on the details. Several previous runs of the
GFS and many GEFS members suggest a split-flow pattern, resulting in
a southern stream cutoff low somewhere over the south-central U.S.
beneath a northern stream ridge over the Mid-Atlantic/Northeast. The
UKMET/ECMWF and many EC members favor more phasing and a deep trough
pivoting across the eastern U.S. The latest operational GFS (12z
10/15) run has trended toward the latter idea, but slower with the
speed of the upper trough.

Adding to the uncertainty late next week is (1) a potential area of
low pressure developing along a stalled frontal zone over the
southwestern Atlantic, (2) how the remnants of Tropical Cyclone
Nicole interact with/enhance blocking downstream over the north
Atlantic, and (3) upstream ridge amplification over the western U.S.
in response to a deepening low in the Gulf of Alaska (the strength
of which models disagree on right from initialization).

Details likely won`t be resolved for at least a few days, but the
potential is there for widespread unsettled weather by late in the


While there could be some patchy fog at CHO, IAD, MRB with brief
MVFR conditions early Sunday morning...VFR conditions will prevail
today through Monday.

Mainly VFR expected Tuesday-Wednesday with westerly to
southwesterly flow around 10 knots.


No problems foreseen on the waters for the remainder of the weekend
and into early next week.

The pressure gradient between a weak stalled front near or
just north of the area and strong high pressure to the south may
result in winds gusting close to Small Craft Advisory levels at
times Tuesday into Wednesday.


Caution stage expected at some of the typically favored sites (e.g.,
Annapolis) over the next few cycles.

Although SW Washington DC was below the guidance forecast at low
tide, it has caught up and now is on pace to exceed the minor
flood threshold at high tide by an inch or two. Have issued a
Coastal Flood Advisory for DC. Alexandria is also outpacing
guidance, and may also exceed minor flood by an inch or two. Will
be monitoring the gauge, and may add Alexandria to the Advisory if
needed in an hour or so. High tide is around 8:00-8:30 pm.


Unseasonably warm weather more typical of late August is
expected Tuesday and Wednesday. Below is a list of record warm
temperatures for those days (October 18th and 19th).

Washington DC Area (Ronald Reagan National Airport, DCA)
October 18th Record Daily High: 85 (set in 1938 and 1881)
October 18th Record Daily Warm Low: 68 (set in 1947 and 1928)
October 19th Record Daily High: 88 (set in 1938)
October 19th Record Daily Warm Low: 65 (set in 1905)
(Temperature records in the Washington DC area date back to 1872)

Baltimore MD Area (Baltimore-Washington International Thurgood
Marshall Airport, BWI)
October 18th Record Daily High: 82 (set in 1945, 1928 and 1908)
October 18th Record Daily Warm Low: 69 degrees (set in 1928)
October 19th Record Daily High: 82 (set in 1947 and 1908)
October 19th Record Daily Warm Low: 67 (set in 1905)
(Temperature records in the Baltimore MD area date back to 1872)

Washington Dulles International Airport VA (IAD)
October 18th Record Daily High: 82 (set in 2007 and 1963)
October 18th Record Daily Warm Low: 60 (set in 1968)
October 19th Record Daily High: 83 (set in 1991 and 1963)
October 19th Record Daily Warm Low: 60 (set in 2011)
(Temperature records in the Dulles VA area date back to 1962)


DC...Coastal Flood Advisory until 10 PM EDT this evening for DCZ001.


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