Area Forecast Discussion
Issued by NWS Sterling, VA-- Remove Highlighting --
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FXUS61 KLWX 240724
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
324 AM EDT Sat Sep 24 2016
A cold front will pass through the area today. High pressure
returns for tonight through Sunday before moving off the coast
Monday. A cold front will pass through the area overnight Monday
into Tuesday. An upper-level low may impact the area during the
middle portion of next week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Cold front dropping southward from Pennsylvania will cross the
region this morning and into the afternoon hours. The frontal
passage will be mainly dry, although an isolated spot shower or
two is possible across northern Maryland this morning, and then
over the higher terrain this afternoon. Otherwise, will see a wind
shift to the north and an increase in clouds. High temperatures
will be noticeably cooler, with highs in the mid to upper 70s for
most, with low 70s possible in NE MD, and mid 80s in central
Virginia where front gets hung up and takes longer to pass.
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
High pressure will nose into the region tonight with continued
north to northeast flow. This will lead to much cooler
temperatures with lows generally 50-60F. Locations from the DC
Metro north and east should see clearing skies, with clouds likely
getting hung up in southern and western areas, especially in the
higher terrain with light northeast upslope flow and some trapped
low level moisture. There may even be some patchy fog/drizzle or a
light shower west of the Blue Ridge.
Surface high pressure will continue to build across the
northeastern US on Sunday, providing for mostly sunny skies for
much of the region. Exception will be across portions of
central/western VA and into eastern WV where more clouds may still
hang on in the light easterly flow. Highs generally in the 70s.
The high will begin to shift offshore Sunday night, promoting
stronger easterly flow, which will likely lead to the development
of a low stratus deck of clouds, especially in western areas.
Again some patchy fog/drizzle or an isolated shower possible west
of the Blue Ridge. Lows mainly in the 50s.
A frontal system will then approach on Monday and cross the region
late Monday night. This will bring a period of rain showers to
the region, mainly Monday night. Highs Monday in the 70s, with
lows Monday night a bit milder ahead of the front, in the low to
.LONG TERM /TUESDAY THROUGH FRIDAY/...
A cold front will move off to the east Tuesday and high pressure
will likely build overhead briefly for later Tuesday and Tuesday
night. Mainly dry and seasonable conditions are expected.
A cutoff upper-level low will pass through the area Wednesday
through Thursday...and there is even some indication that it could
hang around until Friday. The exact location of the upper-level
low is very important. If it remains to the north and east...then
a westerly flow will allow for dry and seasonable conditions over
our area for most of this time. However...if the low drops farther
south and west...then it will tap into moisture from the Atlantic
at the same time coastal low pressure develops near the Mid-
Atlantic Coast. This would bring plenty of clouds along with
chances for rain. Latest forecast will be a blend of these two
solutions...but will lean slightly toward the first scenario which
keeps the upper-level low to the north. This lines up with most
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
Cold front crossing the region this morning will bring increased
clouds to the area today. A period of MVFR ceilings likely at
BWI/MTN/MRB in the 12-18z timeframe. Ceilings currently forecast
to remain above 3000 feet at DCA/IAD, however there is the
possibility for a period of MVFR ceilings at these sites as well.
Conditions will improve to VFR area-wide after 18z. Later tonight,
an MVFR stratus deck likely develops at CHO with a slight chance
of some patchy fog/drizzle. Otherwise, VFR expected elsewhere into
Sunday. Winds light and variable early this morning will turn
north/northeasterly following frontal passage, with speeds up to
about 10 knots.
Additional development of sub-VFR conditions (primarily ceilings)
possible Sunday night into Monday, mainly MRB/CHO. Another period
of sub-VFR conditions possible Monday night in rain showers with
A cold front will move off to the east Tuesday and VFR conditions
are likely as high pressure builds into the area. An upper-level
low may impact the area during the middle portion of next week.
Details are highly uncertain at this time.
As a cold front crosses early this morning, will see a surge of
wind, with gusts up to about 20 knots with and behind the front.
Thus, a Small Craft Advisory remains in effect until 2 pm. Winds
taper off this afternoon. An additional wind surge is possible
tonight into Sunday morning with near-SCA conditions possible once
again. Sub-SCA conditions then return by Sunday afternoon and
Southerly winds will then be on the increase Monday and Monday
night ahead of an approaching cold front, with SCA conditions
A cold front will move off to the east Tuesday. A small craft
advisory may be needed for portions of the waters Tuesday
morning...but high pressure should briefly build overhead for
later Tuesday into Tuesday night.
An upper-level low may develop overhead...and this may cause
coastal low pressure to develop depending on how strong this
system is and exactly where the upper-level low tracks. Details
are highly uncertain at this time...but a small craft advisory may
be needed for portions of the waters Wednesday night and
Anomalies remain elevated, but a northerly flow should keep water
levels below minor flooding thresholds through tonight. However,
winds will shift to the east and southeast Sunday through Monday
night. Minor tidal flooding is possible...especially Monday into
Monday night when the onshore flow will be strongest.
Unusually warm weather has persisted over the area for
quite some time. Autumn-like temperatures will finally make an
appearance over the weekend likely bringing low temperatures at
DCA below 60 degrees for the first time since June 9th, or 106
days ago. The record most consecutive days at or above 60
degrees in the Washington DC area is 112 set in 2012.
MARINE...Small Craft Advisory from 6 AM this morning to 2 PM EDT this
afternoon for ANZ530>534-537>543.