Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
936 PM EDT Wednesday Jun 19 2013
Synopsis...
high pressure over the Great Lakes will build into the middle-
Atlantic tonight then move offshore through the end of the week.
High pressure will remain offshore over the weekend...then a cold
front may approach during the early to middle portion of next
week.
&&
Near term /through Thursday/...
Coastal Flood Advisory was issued...see tides section below...
Previous discussion...
cumulus field will continue to diminish early this evening with the
exception of the central foothills of Virginia. An upper level
trough axis is currently stretched from the Long Island Sound down
to SW Virginia and will continue to push eastward overnight. Showers and
isolated thunderstorms have formed this afternoon in
Nelson...Albemarle...Augusta Virginia in response to a weak cold front
that stalled...slightly higher dewpoints and trapped instability.
Activity is expected to cut off in the next hour or so but middle level
clouds will persist into the morning for the central foothills.
Radiational cooling will occur for areas outside the clouds
overnight with min temperatures dropping to the low to middle 50s. Patchy fog
is possible for isolated areas mainly west of the Blue Ridge mountains
High pressure will move to our NE Thursday and sunshine and calm southeast
winds are expected. In the higher elevations...foothills and
western slopes...models are depicting low level convergence. Forecast
soundings depict steep lapse rates and moisture in the middle levels.
Showers and isolated thunderstorms are possible for these areas.
Severe is not expected.
&&
Short term /Thursday night through Friday/...
high pressure remains off the coast on Friday. Friday looks to be
a similar day to Thursday...with mostly sunny skies and a small
chance of afternoon convection firing over the mountains.
Temperatures will moderate to near normal.
&&
Long term /Friday night through Wednesday/...
high pressure remains off the coast over the weekend...with moisture
gradually increasing on southerly flow. There may be more clouds
later in the weekend...but weak forcing means that any diurnal
convection may still be relegated to the higher terrain.
Temperatures are expected to warm to above normal this
weekend...with maxima near 90 on Sunday.
Warm weather is expected to continue into early next week. There are
signs of high pressure weakening and shortwave energy affecting the
area at some point in time. There is some uncertainty with regard to
timing...so will stick with HPC 20-30 probability of precipitation during this time.
&&
Aviation /02z Thursday through Monday/...
clouds will continue to diminish tonight with the exception of
cho. Scattered to broken middle level clouds will continue at cho this
evening. MVFR stratus possible at cho early Thursday
morning...otherwise VFR for the valid taf period.
High pressure will bring mostly quiet weather this week and
weekend.
&&
Marine...
high pressure builds in late tonight and then moves off the coast
for the end of the week. High pressure looks to remain offshore
over the weekend as well. Am not expecting Small Craft Advisory conditions during
this time.
&&
Tides/coastal flooding...
tidal anomalies will continue to rise through the next few days
as southeasterly winds continue. Current anomalies are less than
a foot but expected to rise to 1 to 1.5 feet overnight and into
Thursday morning. A coastal Flood Advisory was lifted for the Maryland
portion of the Chesapeake Bay.
&&
Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...coastal Flood Advisory until 9 am EDT Thursday for mdz007-011-
014-017-018.
Virginia...none.
WV...none.
Marine...none.
&&
$$
Update...Sheffield
