Severe Thunderstorm Warning 231, NWS Baltimore/Washington

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
946 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/...
Stalled frontal boundary bisects northern third of the CWA as of 9
AM this morning. This front will drift south to near a line from
Petersburg WV to Quantico VA to Solomons MD by mid-afternoon.
North of this boundary, winds will become northerly causing dew
points to drop. As such, more stable conditions are expected and
have trimmed POPs back for this afternoon. Along and south of the
boundary, instability will rise this afternoon. Diurnal showers
and thunderstorms should develop again across the central
Shenandoah Valley to around the Charlottesville area this
afternoon. The right-entrance region of an upper-level jet streak
may aid in a loosely organized band of thunderstorms passing
through this area. Given CAPE values forecast to be 2000+ J/kg and
effective bulk shear of 35-40 kts as well as PWATs approaching 2
inches, added a mention of gusty winds and heavy rain for these
areas.

More isolated showers and thunderstorms are expected further east
into the Fredericksburg VA/southern MD area later this afternoon
into early evening. With the loss of heating, any convection
should wane shortly after sunset.

&&

.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 /14Z WEDNESDAY THROUGH SUNDAY/...
Prevailing VFR conditions expected today and tonight. TSRA
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 late this afternoon
and early evening, but coverage is expected to be isolated.
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 minimums 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/DFH
SHORT TERM...HAS
LONG TERM...LFR
AVIATION...HAS/LFR
MARINE...HAS/LFR
CLIMATE...HAS/LFR

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1031 AM EDT WED JUL 27 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0833 PM     TSTM WND DMG     3 SE GLENORA            38.06N  77.75W
07/26/2016                   SPOTSYLVANIA       VA   PUBLIC

            SEVERAL LARGE TREES DOWN ALONG BREAKNOCK ROAD

&&

EVENT NUMBER LWX1604582

MSE