Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
220 PM EDT Wednesday Jun 19 2013
Synopsis...
high pressure over the Great Lakes will build into the middle-
Atlantic tonight then moves 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 tonight/...
have a few showers popping up across the central Shenandoah Valley
and Potomac Highlands early this afternoon...maybe even a few
sprinkles into the Virginia Piedmont. Dewpoints were still in the
60s in this area. But northerly winds behind a cold front were
bringing lower dewpoints in the 50s closer to the Mason Dixon
line. These lower dewpoints will spread south through the rest of
the afternoon and evening...and any isolated convection across the
south/southwest portion of the County Warning Area will dissipate.
High pressure over the Great Lakes builds over the northeast and
middle-Atlantic tonight. Clouds from this afternoon will break up and
the sky will clear out this evening...paving the way for radiational
cooling and cooler temperatures tonight.
&&
Short term /Thursday through Friday/...
high pressure moves off the coast during the daytime Thursday.
Atmosphere remains relatively dry. With light flow..can/T rule out
isolated showers or thunderstorms in the afternoon over the higher
terrain otherwise dry conditions with sunshine can be expected.
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 Tuesday/...
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 /18z Wednesday through Monday/...
clouds will scatter through late afternoon...with the potential for
clearing skies occurring late tonight. MVFR fog possible at cho/mrb
late at night...otherwise VFR for the valid taf period.
High pressure will bring mostly quiet weather late in the week into
the weekend.
&&
Marine...
Small Craft Advisory has been cancelled as north/NE winds have diminished. 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.
&&
Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...none.
&&
$$
Bpp
