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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 131846
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
246 PM EDT Thu May 13 2021

.SYNOPSIS...
High pressure will gradually drift eastward from the Midwest
today and Friday before reaching the east coast by Saturday.
Mostly dry conditions and near seasonable temperatures are
expected to continue during this time. A warm front may lift
northward towards the area early next week and stall nearby.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
An expansive area of high pressure, centered over the Great
Lakes, extending across much of the eastern half of the CONUS
continues. Aloft, a quasi-split flow continues as a string of
shortwave energy slides across our south and east, resulting in
some mid-level CU developing across the area that is expected to
diminish late tonight. Some showers have developed across
southwestern PA. However with a rather large dew point
depression, expect conditions to remain dry during this time.
Temperatures will remain just slightly below normal for this
time of year; in the mid- upper 60s to low 70s for most with 50s
in the mountains.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...

-- Changed Discussion --
A second piece of shortwave energy will slide across our south
Friday as subsidence upstream continues to produce a large
surface high across the Midwest. With the upper level jet
positioned in a NW to SE orientation across the CWA, yields the
potential for multiple waves of shortwave energy to cross the
region through Saturday. However, with the aforementioned high
to our west slowly traversing eastward during this time, should
result in mostly dry conditions continuing throughout much of
the weekend. However, cannot fully rule out a spot shower and/or
thunderstorm during this time. CAPE values are rather low;
ranging between 200-500 J/Kg with unimpressive mid-level lapse
rates, forcing, and rather low dew points in conjunction with a
lack of significant forcing. Therefore, think the potential for
any convective activity is low at this point in time, but non-
zero nonetheless. Best potential for any shower activity looks
to be mainly during the afternoon hours and along and west of
the Blue Ridge. Temperatures Friday will be a smidge higher than
today, with highs Saturday reaching the low to mid 70s across
the metros and upper 50s to low 60s over the mountains.
-- End Changed Discussion --


&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...

-- Changed Discussion --
High pressure will relax and slide to the east Sunday. This will
allow for a mid-level disturbance from the west and a jet streak
aloft to bring a chance of showers and perhaps a thunderstorm or
two to the region Sunday afternoon and evening. Highs will be in
the 70s.

The chance for showers lingers Sunday night and Monday as a weak
surface boundary develops and meanders across our southern zones or
just to our south. The chance for any thunderstorms seems more
probable Monday afternoon with additional daytime heating and the
surface boundary nearby. Highs Monday should be in the 70s as
well.

By Tuesday and Wednesday, the front will have dropped south into
the Carolinas as an area of high pressure drops in from the north.
Cooler and drier air should accompany the high Tuesday. As the high
moves overhead Wednesday before pushing east, a return flow should
develop and allow our temperatures on Wednesday to become more
average or above average.
-- End Changed Discussion --

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
VFR conditions expected to continue across the terminals through
the end of the weekend as high pressure maintains control.
Although conditions are expected to remain dry during this time,
cannot fully rule out the slight chance for an isolated shower
and/or thunderstorm Friday and Saturday mainly west of I-95.

High pressure will weaken and move east to allow for a chance of
showers or perhaps a thunderstorm Sunday. VFR conditions. Any
heavy showers could briefly reduce conditions to MVFR. Winds
generally south 5 to 10 knots. Slight chance for showers Sunday
night. Winds light and variable. A chance for showers and a
thunderstorm or two Monday. VFR could become MVFR in heavier
showers. Winds southeast 5 to 10 knots Monday.
-- End Changed Discussion --

&&

.MARINE...

-- Changed Discussion --
Mostly quiet weather is expected to continue over the waters
through the weekend as high pressure slowly moves overhead,
before shifting offshore by Sunday. Northerly winds are expected
to continue before becoming more southerly on Sunday. Winds
should remain below SCA criteria during this time, however
cannot fully rule some isolated gusts up to 18 kts.

High pressure to our east to allow for a chance for showers and
perhaps a rumble of thunder Sunday. Slight chance to a chance
for showers and thunderstorms Sunday night and Monday. However,
no marine hazards expected at this time Sunday through Monday.
-- End Changed Discussion --

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$
SYNOPSIS...MSS
NEAR TERM...MSS
SHORT TERM...MSS
LONG TERM...KLW
AVIATION...MSS/KLW
MARINE...MSS/KLW