Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 270755
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
355 AM EDT Wed Jul 27 2016

.SYNOPSIS...A front will remain stationary across the area through
Thursday then lift north Thursday night. Low pressure will track
across the area Friday. High pressure builds for early next week

&&

.NEAR TERM /THROUGH TONIGHT/...A frontal boundary is near the MD/PA
border this morning and warm and humid conditions will continue
across the Mid-Atlantic region. A weak shortwave trough will move
to the north this morning and a few showers are possible. Winds
are expected to be light and northerly and dewpts will drop into
the upper 60s across the nrn outlook area today. The frontal
boundary will move south of most of the region today and likely
stall near central VA again. Scattered showers and thunderstorms
are expected again today with the highest chance across central
VA. Higher instability due to higher dewpts will also lead to a
few strong to severe storms from the central Shenandoah Valley to
southern MD. A few showers and thunderstorms can not be ruled out
further north as instability will still be present. Higher dewpts
will likely be further north along the Chesapeake Bay due to a
onshore component to the wind. Temps will be cooler today with
more cloud cover and heat indices should stay below 100 with the
exception of the central Foothills where the dewpts are higher.

Thunderstorms will be diurnally driven and should diminish this
evening. Dewpts will rise back into the 70s resulting in another
mild evening.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...500mb flow becomes W-SW
Thursday in response of an approaching shortwave trough across
the TN Valley. The frontal boundary will lift northward Thursday
and Thursday night and the Mid-Atlantic will be in the warm
sector. Scattered showers and thunderstorms are expected across
the region Thursday afternoon as energy ahead of the shortwave
trough moves into the region. Convection will likely persist into
the evening hours and a few strong to severe storms are expected.
Guidance has been depicting a sfc low moving near or across the
region Thursday night into Friday. Uncertainty is low on timing
and location but heavy rainfall is possible in an unstable moist
airmass. The trough will pass overhead Friday and showers and
thunderstorms will be possible. Subsidence behind the trough will
likely lead to dry conditions Friday night.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...Multiple sfc waves and
impulses aloft are fcst to move through the area during the
weekend with the most significant of these Fri afternoon. Showers
and t-storms will remain in the fcst through Mon as front remains
nearly stationary across the area. By Mon night, most guidance
show front pushing far enough south with sufficient dry air as
weak high pressure builds in to suppress shower development
everywhere with temperatures returning to more seasonable values
in the mid to upper 80s.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... Prevailing VFR conditions
expected today and tonight. SHRA/VCTS expected at CHO this afternoon.
SHRA/VCTS possible at MRB/IAD/DCA however confidence is low. Coverage
will increase Thursday afternoon with SHRA/VCTS expected across
the region. Convection will continue Thursday night into Friday
and some SHRA/TSRA may produce heavy rainfall resulting in longer
sub-vfr conditions overnight Thursday into Friday.

Periods of rain during the weekend especially on Sun which may
cause some restrictions. Improving weather Mon night on as weak
high pressure builds in.

&&

.MARINE... Winds less than 15kts will continue on the waters. Showers
and thunderstorms are possible on the waters today and gusty winds
are expected in activity. Scattered showers and thunderstorms
expected Thursday afternoon through Friday resulting in the
potential for gusty winds through the period. SMW may be required in
showers and thunderstorms.

Winds generally 10 kt or less outside of thunderstorms, but winds
and waves higher near thunderstorms.


&&

.CLIMATE...Record high minumums were either tied or broken at DCA
and IAD airports.

New record high minimum of 80F degs set at DCA yesterday breaking
the old record of 79F set in 1987.

Record high minimum of 76F degs set at IAD yesterday tying the
previous record of set in 2005.

&&

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

&&

$$
SYNOPSIS...LFR
NEAR TERM...HAS
SHORT TERM...HAS
LONG TERM...LFR
AVIATION...HAS/LFR
MARINE...HAS/LFR
CLIMATE...LFR



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