Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 170138
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
938 PM EDT Fri Jun 16 2017

.SYNOPSIS...
A nearly stationary front will meander across the region through
tonight before lifting northeast of the area as a warm front
over the weekend. A cold front is forecast to cross the area
Monday into early Tuesday.

&&

.NEAR TERM /THROUGH SATURDAY/...
A nearly stationary remains draped across eastern West Virginia
then along the Blue Ridge Mountains. Slow moving showers and
thunderstorms have mostly cleared the area where the Flash Flood
Watch had been issued earlier, so have allowed it to expire.
However, some eastern portions of the forecast area have yet to
be worked over, while shortwave energy moving in from the
southwest may still manage to pop some showers or even a rumble
of thunder through the rest of the night. Multiple models
indicate showers may continue to develop over the metro, so have
bumped pops to chance through the rest of the night. Otherwise,
with fairly widespread rainfall, areas of low clouds and fog
are expected late tonight due to high amounts of low-level
moisture getting trapped underneath the nocturnal inversion.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
The boundary will mostly dissipate while lifting to our
northeast Saturday while a cold front moves into the central
CONUS. A southerly flow will usher in warm and humid condtions
across the area. The instability will lead to more showers and
thunderstorms. Thunderstorms will be capable of producing
locally heavy rain and gusty winds. The best chance for
thunderstorms will be during the afternoon and evening hours.
Convection will gradually dissipate Saturday night and areas of
low clouds/fog are expected overnight into early Sunday.

The south to southwest flow will strengthen Sunday ahead of the
cold front that will be moving into the Ohio Valley. Hot and
humid conditions are expected. This will lead to the chance of
thunderstorms Sunday afternoon into Sunday night. Shear
profiles will be a bit stronger...especially across the western
portions of the CWA so severe thunderstorms are possible.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Upper trough axis moves through the Great Lakes as
instability increases with a cold front approaching from the
west on Monday. Low level southerly flow ahead of the front
will advect moisture to our region... PW near or above 2 inches.
We will be at the right entrance region of an ~85kt jet
enhancing strong upper level divergence. Heavy rain is a concern
(cannot rule out any flash flooding) and strong convection
expected.

Cold front moves through late Monday night into early Tuesday
and lingers nearby into Tuesday night. Some precipitation
possible Tuesday with cold front nearby. Then a slight chance of
showers and thunderstorms late on Wednesday with upper level
trough moving through... dry conditions on Thursday... and then
a quick moving front on Friday.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
TSRA chances diminishing but expected to continue through at
least 03Z. IFR/SubIFR conditions are possible from heavy
rainfall along with locally gusty winds in thunderstorms.
Convection should diminish in coverage overnight. Areas of low
clouds and fog are expected late tonight into Saturday morning.
MVFR conditions are definite and IFR conditions are looking
more likely.

A south to southwest flow will continue to usher in plenty of
moisture Saturday through Sunday. Showers and thunderstorms are
expected, particularly Saturday, and particularly during the
afternoon and evening hours each day. Areas of low clouds and
fog are likely during the overnight and morning hours each day.

Showers and thunderstorms possible Monday into Tuesday due to a
cold front. Sub-vfr conditions possible at times during this
period. Conditions improve/vfr Tuesday into Wednesday.

&&

.MARINE...
Winds should remain below SCA criteria through Saturday. Showers
and thunderstorms are likely this evening, diminishing overnight.
Thunderstorms may contain locally gusty winds, but at this time,
the threat of special marine warning gusts appears to have
diminished.

The gradient will strengthen by Saturday night and a Small
Craft Advisory is in effect for middle portions of the Bay and
the lower Tidal Potomac River. A Small Craft Advisory may be
needed for portions of the waters Sunday and Sunday night as
well.

Showers and thunderstorms are expected Saturday and possible
again Sunday...especially during the afternoon and evening hours
each day.

Showers and thunderstorms expected Monday into Tuesday due to a
cold front. Wind gusts will be at or above the small craft
advisory threshold Monday into early Tuesday. Winds improve
Tuesday into Wednesday.

&&

.TIDES/COASTAL FLOODING...
Water level departures running around a foot above normal this
evening.

Believe departures should be gradually increasing though the
weekend, although guidance not exactly supporting that
assertion. That places the latest forecast at the upper end of
the guidance spread. Minor tidal flooding is expected in St
Marys county for the high tide cycles Saturday.
Elsewhere...water levels should remain below minor flooding
thresholds through the high tide cycle this evening.
However...minor tidal flooding is possible during the high tide
cycle Saturday.

Advisory for St Marys County remains in through Saturday
morning.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until noon EDT Saturday for MDZ017.
VA...None.
WV...None.
MARINE...Small Craft Advisory from midnight Saturday night to 6 AM EDT
     Sunday for ANZ532>534-537-540-541-543.

&&

$$
SYNOPSIS...BJL/RCM
NEAR TERM...BJL/RCM
SHORT TERM...BJL/RCM
LONG TERM...IMR
AVIATION...BJL/IMR/RCM
MARINE...BJL/IMR/RCM
TIDES/COASTAL FLOODING...BJL/RCM



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