Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 211853
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
253 PM EDT Sun Aug 21 2016
A cold front will continue to move east across the area into this
evening. High pressure then builds over the area into Tuesday
before persisting offshore through the rest of the week.
.NEAR TERM /THROUGH TONIGHT/...
As of 2pm, prefrontal line of scattered heavy showers with
isolated thunderstorms has developed from Baltimore to Nelson Co
VA. The actual front is seen as a line of showers in central WV.
The prefrontal line will continue to move east from the Blue Ridge
and north-central MD through the rest of the afternoon. These
cells will continue to develop with lightning activity increasing
from MLCAPE 1500 j/kg and effective shear around 30 kt. Gusty
winds can be expected from these cores with localized damaging
Heavy rates of 1-2 inches per hour. The line orientation is nearly
parallel to the mean flow, so some cells have been training. Will
need to continue to look out for localized flash flooding.
Cold front will shift east across the area through the early
evening. NWly flow behind the front will gust around 20 mph
overnight. Min temps low to mid 60s with mixing flow keeping fog
limited to sheltered valleys.
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
1027mb surface high pressure shifts overhead through Monday night.
Cool and dry high pressure with max temps Monday and Tuesday low
80s with min temps Monday and Tuesday night generally low 60s,
slightly less Monday night in the calm under the high pressure
Light onshore flow Tuesday becomes southerly Tuesday night as the
high sets up along the northern Mid-Atlantic coast.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
High pressure will move offshore during the middle of the week
leading to a warming trend in temperatures and increasing humidity.
A strong middle to upper level ridge will build over the interior
southeastern United States late in the week and persist into the
weekend. Meanwhile, a cold front will drop into the area from the
northwest on Friday then stall and weaken near or just south of the
area. This will lead to an increased chance for showers and
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Gusty showers and thunderstorm across DC metros shift east through
the rest of the afternoon. Cold front crosses from the west
through the early evening. NWly flow gusts 20 kt overnight. VFR as
high pressure builds through Monday night and persists offshore
through the middle of next week.
VFR continues Wednesday into Thursday with southeasterly winds at
or below 10 knots.
Special marine warnings expected rest of the afternoon as gusty
showers and thunderstorms shift east through the area ahead of a
cold front. Small craft advisory for 20 kt southerly gusts ahead
of the front and then for NWly 25 kt gusts tonight behind the
cold front. Winds ease through Monday morning with high pressure
building overhead Tuesday morning for a dry and tranquil period
which continues into the midweek.
Southeasterly flow around high pressure departing to the east of
the waters may result in gusts close to Small Craft Advisory
levels Wednesday into Thursday.
MD...Coastal Flood Advisory from 6 PM to 11 PM EDT this evening for
Coastal Flood Advisory until 8 PM EDT this evening for MDZ017.
MARINE...Small Craft Advisory until noon EDT Monday for ANZ530>534-
Small Craft Advisory until 10 AM EDT Monday for ANZ535-536.