Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 190749
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
349 AM EDT Fri Aug 19 2016
.SYNOPSIS...Weak high pressure builds in through Saturday with a
cold front crossing the area Sunday evening. High pressure
returns for the first half of next week.
.NEAR TERM /THROUGH TONIGHT/...Mid-high level clouds continue to
stream into the Mid-Atlantic region early this morning due to
westerly flow aloft. A shortwave trough will approach the region
from the TN valley today. Iso-sct showers and an isolated
thunderstorm are possible mainly across the VA highlands and
Shenandoah Valley where forcing and instability is higher. As the
disturbance tracks eastward into this evening a few showers and
thunderstorms may pop-up south and east of the Washington DC
metro. Rainfall amts will be light in any activity.
Mostly sunny conditions will allow temps to reach the low 90s
east of the Blue Ridge today...mid to upper 80s elsewhere.
.SHORT TERM /SATURDAY THROUGH SUNDAY/...Similar conditions on
Saturday as westerly flow aloft continues. Iso- sct showers and
an isolated thunderstorm are possible Saturday afternoon mainly
across the higher elevations. Activity should diminish into the
evening. Warm conditions continue Saturday but may be a deg or two
cooler than today due to more cloud cover. Temps will still reach
U80S/L90s east of the Blue Ridge.
Attention shifts to a cold front that will move into the Ohio Valley
Saturday night. This system is associated with a deep upper level
trough that will swing across the Great Lakes and New England
Sunday. The cold front will move through the Mid-Atlantic during the
day Sunday. Strong moisture advection is expected ahead of the front
and showers and sct thunderstorms are expected. The wind field will
increase Sunday afternoon and a few thunderstorms may become strong
to severe however coverage seems isolated at this time. The risk is
greater across NY/PA. The bigger threat will be heavy rain on
Sunday. Widespread amounts of a half inch in 6 hours are probable
east of the Blue Ridge Sunday afternoon. Greater amts of near an
inch are possible along the I-95 corridor. Locations closer to the
better forcing such as northeast MD including the City of Baltimore
may see some flash flooding Sunday afternoon and into the evening.
Training storms capable of flooding are possible in this synoptic
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...Cdfnt clears the fcst
area by 03Z Mon with showers ending. Dry wx most of next week as
ridge builds over the area sfc and aloft. Temps below normal early
next week then gradually warm up. High pressure begins to weaken
at the end of next week with moisture returning to the area with
showers possible over the higher terrain next Fri Aug 26. By the
end of next week, we`ll be also paying attention to the tropics as
all of the GEFS members show a tropical cyclone north of Puerto
Rico on a track WNW to the east of the Bahamas.
.AVIATION /07Z FRIDAY THROUGH TUESDAY/... VFR conditions expected
through the next 36 hours. Isolated showers and thunderstorms are
possible in the afternoon hours today and Saturday mainly at CHO-
MRB. Sub-vfr conditions are possible in activity. A cold front
will cross the terminals Sunday and widespread showers are
expected. Flight restrictions are expected and TSRA causing gusty
winds are also possible Sun afternoon.
Showers end by 03Z Mon as cdfnt sweeps through the area. NW winds
Sun night and Mon as high pressure builds from the west. VFR all
of next week under high pressure.
.MARINE...Sub-SCA conditions on all the waters through Saturday. An
isolated shower or thunderstorm is possible each afternoon which
could bring gustier winds.
No marine hazards expected Sunday through Sunday night. Winds south
becoming southwest around 10 knots.
Small craft advisory conditions are likely Sun night through Mon
night as winds shift to the NW behind cold front.