Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 260122
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
922 PM EDT Sun Jun 25 2017

.SYNOPSIS...
High pressure will build west of the area through Tuesday as a
series of weak boundaries cross the region. The high will then
cross the region Wednesday and settle over the western Atlantic
Ocean late in the week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
...Update to add Small Craft Advisory for tonight across the
Maryland Chesapeake Bay north of Drum Point. Previous discussion
follows...

Surface high pressure will remain centered over the Midwest
into the Tennessee Valley tonight while an upper- level trough
remains overhead. A west to northwest flow will allow for dry
and cool conditions for this time of year. Leaned toward the
cooler guidance thinking that the atmosphere will decouple...and
with mainly clear skies...light winds and low dewpoints this
does favor radiational cooling. Min temps are forecast to range
from the 40s in the colder valleys of the Potomac Highlands and
Shenandoah Valley...to the 50s across most other locations...to
the middle 60s in downtown Washington and Baltimore.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Another weak trough/boundary will move near the region Monday.
Again, little if any sensible impacts expected. Will once again
see an instability-driven cumulus field develop. A very low
chance of a shower exists, mainly north. The region will remain
in westerly flow with gusts up to about 20 mph. Highs from the
mid 70s to low 80s. Quiet weather will continue Monday night,
with lows in the 50s to low 60s.

The highest chances of any precipitation in this stretch will
come on Tuesday as an upper trough and its surface reflection
move across the area. With a small amount of instability due to
the anomalously cool temperatures aloft, there will likely be
some isolated- scattered showers and possible thunderstorms
around the area. This will also be the coolest day with highs in
the 70s area-wide. High pressure will build in overhead, with
lows in the 50s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
High pressure will be in control Wednesday, bringing dry
conditions and below normal temperatures, before sliding
offshore Thursday.

As high pressure moves over the western Atlantic, warmer
temperatures and increasing chances of showers and thunderstorms
will develop Thursday night through Sunday. The best chance for
showers and storms will be Saturday and Sunday.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR expected through at least Tuesday night with a fair weather
cumulus deck each day. Main concern will be an isolated
showers/thunderstorms on Tuesday. Otherwise, winds generally
westerly with gusts to about 20 knots during the daylight hours.

VFR conditions Wednesday through Friday. Winds northwest
to start will turn south/southwest by late in the week. Chances
for showers/thunderstorms are introduced by Friday.

&&

.MARINE...
Small Craft Advisory is in effect until 5 am for the Maryland
Chesapeake Bay north of Drum Point. As cooler air moves over
the warm water temperatures overnight, gusts up to 20 knots are
expected.

Wind field looks slightly lower on Monday, but gusts may again
approach SCA-criteria Monday afternoon. Have kept forecast below
at this time.

Westerly flow will continue on Tuesday with marginal SCA
conditions possible. There will also be an increased chance for
some isolated-scattered showers/thunderstorms.

No marine hazards expected Wednesday and Wednesday night. Winds
south 5 to 10 knots. Small craft advisories may be needed Thursday
and Thursday night. Winds southwest 10 to 15 knots gusts 20
knots.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 5 AM EDT Monday for ANZ530>533-
     538>541.

&&

$$
SYNOPSIS...MM
NEAR TERM...BJL/MM
SHORT TERM...MM
LONG TERM...KLW
AVIATION...BJL/MM/KLW
MARINE...BJL/MM/KLW



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