Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 241851
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
251 PM EDT Fri Jun 24 2016
A slow moving front will slide south away from the region tonight.
High pressure will dominate over the weekend. A cold front will
approach the area Monday before crossing the area Tuesday. High
pressure will return for mid-week.
.NEAR TERM /THROUGH SATURDAY/...
As of 2PM...a weak stationary front remained draped across the
area. The wind shift line is hard to determine, and the pressure
trough stretches west-to-east across the CWA..but the drop in dew
points remains near the Pennsylvania border. Thus we remain in a
moist and unstable air mass with dew points not far from 70 in
much of the area. Combined with afternoon sunshine and an
approaching short wave...and we should see continued scattered
showers and thunderstorms this afternoon into early this evening.
Profiles remain decent for sporadic severe...but plenty of dry air
aloft is helping keep storms from getting too tall. This may
change for a time late today...especially in central Virginia and
southern Maryland...so the risk of isolated severe weather
remains. Main risk is hail and gusty winds...with a secondary
threat of locally heavy rain given that the storms so far are not
Tonight...the trough will pass the area this evening and
convection will wane from NE to SW. The high to the north will
nudge southward and easterly flow will take over. Guidance is
suggesting a low cloud deck will develop...and the rains which
much of the area has had suggest some patchy fog may try to form
as well. Lows will be in the 60s. Low clouds and patchy fog early
Saturday should break for sun over most of the area and highs will
return to the low-mid 80s. However, with drier air pushing in from
the north, it should be more comfortable.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Ridge builds across the area aloft on Sunday then gets pushed east
of the area by a shortwave on Monday. At the surface...high
pressure will shift east of the area on Sunday but a tongue will
extend southwest across the region. By Monday the next cold front
will be approaching from the west. The high will promote possible
patchy fog early Sunday...otherwise sunshine will dominate and it
will be slightly warmer than Saturday. By Monday clouds will
increase and showers and thunderstorms will spread into the area
by afternoon. Will need to watch any severe threat.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Seasonably warm and humid conditions are expected Monday in
southerly flow. A cold front will move in from the west during the
day and may trigger showers and thunderstorms. Shear looks like it
won`t be as impressive as with recent events, but still decent
veering (southerly at the surface to westerly at 500 MB).
The front may get hung up over eastern parts of the area Monday
night into Tuesday before weakening. High pressure will bring a
return to dry weather briefly Tuesday night into Wednesday before
another system approaches late in the week.
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
Main concern this afternoon into early this evening is scattered
showers and thunderstorms. Any storm may bring hail and gusty
winds but coverage should be hit-or-miss. Cigs and vis may also be
reduced significantly as any storm passes. Overnight into early
Saturday, low clouds and fog are possible which may bring cigs and
vis down to at least MVFR if not IFR. Improvement by Saturday
afternoon with high pressure followed by perhaps some more patchy
fog Saturday night into Sunday morning. VFR Sunday aft to Monday
morning, then sub-VFR possible in Monday afternoon/evening
showers and thunderstorms.
Stalled front in the area combined with an approaching upper level
disturbance is promoting shower and thunderstorm development.
Storms may produce gusty winds this afternoon into early this
evening. Otherwise, winds should be below 18 knots through Monday
morning as high pressure noses in from the north and northeast
through the weekend. Cold front approaching Monday may bring SCA
gusts via southerly channelling. A brief period of SCA level
gusts is possible again Tuesday in westerly flow as high pressure
builds in behind the front.