Scientific Forecaster Discussion
fxus61 klwx 171424
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1024 am EDT Tue Sep 17 2019
a cold front to our south will push into the southeastern U.S.
Through tonight as Canadian high pressure builds to our north.
This high will dominate over the northeast and mid-Atlantic
region for the balance of the work week, promoting dry
conditions and cooler temperatures. The high will settle to our
south this weekend.
Near term /through tonight/...
latest surface analysis depicts a cold front across southern Virginia
as northeasterly breezes and cloudy skies dominate across the
County Warning Area. Widely scattered showers are moving across portions of
southern Maryland and adjacent Northern Neck of VA, tracking off to
the southeast as winds turn out of the north-northwest above 5kft. Clouds
will be slow to erode today as winds remain out of the east
northeast, with temperatures topping out in the middle 70s to
lower 80s. Will carry a chance for showers across central Virginia
into early this afternoon, with drier air working into the
region late this afternoon and evening. This drier air was
evident with this mornings 12z iad sounding above 700mb.
Conditions will stay dry overnight as skies clear and winds
slacken. This will promote patchy fog in the sheltered valleys
and rural areas toward daybreak. Temperatures overnight will be
much cooler than previous days, dropping into the low to middle
50s to near 60 degrees in the city centers.
Short term /Wednesday through Thursday night/...
high pressure will remain in control through the period. Dry
conditions with light northeast winds, becoming more variable as the
high pressure settles overhead. Dry conditions and cool temperatures
in the 70s during the day, followed by temperatures in the 50s at
Long term /Friday through Monday/...
surface high pressure will slowly ease off the coast through the
extended portion of the forecast, as ridging remains in place aloft.
This setup will promote a warming trend as well as increases in
humidity (dewpoints rising from upper 40s/lower 50s to above 60).
But the forecast will remain rain-free until perhaps Monday, when an
approaching cold front could perhaps support shower (thunderstorm?)
Activity. Pops (20-30%) will be focused on the Potomac Highlands at
Aviation /14z Tuesday through Saturday/...
light northeasterly breezes today at the terminals today in the
wake of a frontal passage. MVFR cigs will improve to VFR this
afternoon as drier air works into the area. One exception will
be cho where MVFR cigs likely hold on until late this afternoon
with a passing shower or two possible.
VFR conditions expected the remainder of the work week as high
pressure dominates to our north and winds remain light and
easterly through Thursday before turning out of the south
Thursday night and Friday.
Small Craft Advisory conditions continue across the main Stem of the Bay and
lower tidal Potomac into this afternoon in the wake of the
frontal passage, slackening toward evening. Small Craft Advisory conditions
likely linger for portions of the Lower Bay/Potomac waters
tonight and into Wednesday. Thereafter, high pressure will
build over the waters through weeks end with lighter winds and
sub Small Craft Advisory conditions expected.
onshore flow through through Thursday will promote higher than
normal tidal anomalies, resulting in the threat for minor tidal
flooding. Currently, no active advisories in place but that will
change over the next couple of days as anomalies continue to
District of Columbia...none.
Marine...Small Craft Advisory until noon EDT today for anz531>533-
Small Craft Advisory until 6 am EDT Wednesday for anz534-537-