Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 302353

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
753 PM EDT Thu Jun 30 2016

A warm front will lift through the area tonight into early
Friday. A cold front will pass through the region Friday night and
high pressure will return for Saturday into Sunday. Low pressure
will pass through the region Monday into Tuesday.


High pressure will continue to move off the coast this evening
and a southerly flow will usher more moisture into the area.
Increased dewpoints have led to some more instability...but
instability is limited since the deepest moisture remains to our
south. A few popup showers are expected this evening...but
coverage will remain isolated to widely scattered due to the lack
of a strong lifting mechanism.

Moisture will continue to advect into the area
overnight...resulting in noticeably more humid conditions. A few
popup showers and perhaps a rumble of thunder are possible...but
coverage will remain isolated to widely scattered due to the lack
of a strong lifting mechanism...with weak isentropic lift combined
with a jet streak being the primary mechanism. Min temps will be
in the 60s for most locations.


A cold front will pass through the Ohio Valley Friday and a
southwest flow ahead of the boundary will continue to usher in
more moisture across the area. It will turn out warm and humid
with highs in the mid to upper 80s across most locations. Some
areas may crack 90. upper-level low will track across
eastern Canada into New England...causing mid and upper-level
winds to strengthen. This will cause shear profiles to strengthen
with 0-6KM shear values most likely between 30 and 40 knots. The
southwest flow will usher in more instability across the
area...and with higher dewpoints in the upper 60s MLCAPE values
are expected to reach 1000-2000J/KG. Showers and thunderstorms are
likely especially from Washington DC on north and east...with
lower coverage expected further south and west. Development of
storms is expected to occur primarily within a pressure trough
which will likely set up near the Catoctin and Blue Ridge
Mountains. From there, the storms will probably expand in coverage
as they head east late in the day. The moderate CAPE and moderate
shear profiles suggest that a few of the thunderstorms may become
severe...with damaging winds and large hail being the primary
threats. The best chance for severe storms will be east of the
pressure trough across the Washington and Baltimore Metropolitan
areas into southern Maryland.

The cold front will pass through late Friday evening into the
overnight and drier air will gradually move in from the north and
west. High pressure will build over the region Saturday into
Saturday night...resulting in sunshine along with noticeably less
humid conditions. There may be some high clouds moving through in
the zonal flow aloft.


A slight chance of showers or a thunderstorm across the southern
half of our region Sunday and Sunday night with a stalled front
along the Virginia and North Carolina state line.

As a storm system develops along the western end of the front and
across portions of the Midwest U.S. Monday into Monday night, the
stalled front will propagate northward as a warm front. This warm
front will usher in more humid and warm air northward to help fuel
showers and a few thunderstorm farther north into northern
Virginia, Maryland and eastern West Virginia Monday into Monday

The next storm system will move across the eastern Ohio Valley
and portions of the mid-Atlantic Tuesday. The chance for showers
and thunderstorms will accompany the storm system Tuesday. The
storm is expected to exit east and move offshore the East Coast
Tuesday night.

High pressure will usher in cooler and drier air into the region
Wednesday. A small wave of upper level disturbances will slide
across the region Thursday to bring back the chance of showers and


VFR conditions are expected through the rest of this evening. An
isolated shower cannot be ruled out...but most areas will be dry.
Patchy fog and low clouds are expected late tonight into Friday
morning. MVFR conditions are likely west of I-95...and IFR
conditions are possible. Near I-95...clouds and a few more showers
overnight are likely to disrupt fog formation and keep cigs and
vis in the VFR range.

Cigs will improve later Friday...but showers and thunderstorms
are expected to develop in the afternoon near the I-95 corridor.
Thunderstorms will be most numerous across the eastern terminals
later Friday afternoon into Friday evening. A cold front will pass
through Friday night. Saturday/Saturday night will be dry with
VFR conditions.

A warm front will approach Sunday before stalling out over the
area Monday into Tuesday. Low pressure will track along the
boundary...bringing unsettled conditions. Uncertainty remains in
the timing


South to southeast winds are expected through Friday...but
gradient winds should remain below SCA criteria. Popup showers
are possible through The
most widespread coverage will be late Friday afternoon and
evening. tonight. More numerous showers and
thunderstorms are expected Friday afternoon into Friday evening.
A few of those thunderstorms may produce gusty winds and hail. A
cold front will pass through the waters Friday night and high
pressure will return for Saturday and Saturday night. A small
craft advisory may be needed for portions of the waters Friday
night and Saturday.

No marine hazards expected Sunday and Sunday night. Winds
northwest around 10 knots Sunday and Sunday night. Low pressure
may bring unsettled conditions Monday into Tuesday.




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