894
FXUS61 KLWX 040117
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
917 PM EDT Sun Aug 3 2025

.SYNOPSIS...
Dry conditions, low humidity, and seasonably cool temperatures are
expected through Monday as wedging high pressure drifts toward New
England. High pressure begins to weaken as it pushes offshore
Tuesday into Wednesday allowing the humidity and shower chances to
return. An area of low pressure will move along the coast with a
weak frontal boundary approaching from the west Thursday and
Friday.

&&

.NEAR TERM /THROUGH MONDAY/...
Elongated high pressure is located north of the area this
evening. Aloft, there is a shortwave trough over the central
Appalachians. A jet streak ahead of this feature has resulted in
a cirrus shield spreading over parts of the area, but these
clouds will depart overnight. Mostly clear skies and light winds
will lead to another cool night with lows in the mid to upper
50s and low 60s (mountains mid to upper 40s and low 50s).
Locations such at Bittinger, MD, Mill Gap/Mustoe, VA, The
Glades, MD, and Bayard, WV could see lows in the upper 30s and
low 40s). Patchy fog is possible, especially in the western
river valleys.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
Surface ridge of 1022-1024mb remains wedged down the eastern side of
the Appalachians Monday. Meanwhile, quasi-zonal flow remains aloft
leading to slightly below seasonal normal temperatures for early
August, low humidity, and dry condition. More sunshine Monday will
lead to highs in the mid to upper 80s east of the Alleghenies with
mid to upper 70s and low 80s across the Shenandoah Valley/Blue
Ridge/Catoctins/higher elevations above 2000 feet. Dewpoints will
rise slightly into the upper 50s and low 60s as the wedge of high
pressure weakens while shifting north and east toward the northern
Mid-Atalntic/interior Northeast. Lows Monday night will fall back
into the low to mid 60s east of the Blue Ridge (Baltimore/Washington
DC metros upper 60s) with mid to upper 50s over the mountains.

Wedging high pressure over the interior Northeast and northern Mid-
Atlantic will continue to weaken Tuesday while shifting offshore
Tuesday into early Wednesday. Meanwhile, a potent upper level trough
will dig across the Great Lakes and through the southeastern U.S
CONUS sending Gulf moisture northward into the region midweek.

Uncertainty in the forecast begins to show up as early as Tuesday
afternoon when some EPS/GEFS members showing light rain/drizzle
arriving across portions of the Shenandoah Valley, central VA
Piedmont, and Allegheny Highlands region. Given the slow nature of
the cutoff upper level trough to the west and the strong high
pressure center settling over northern New England/southeast Quebec,
the slower solutions are more likely to verify. With that said,
carrying 15 to 25 percent pops mainly west Alleghenies and over the
southern Shenandoah Valley/central Blue Ridge where ample moisture
will build in first due to upslope easterly/southeasterly flow. Once
again, confidence is low for precip Tuesday given the residual dry
air aloft from wedging high pressure fighting off light/moist
easterly flow.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Plenty of uncertainty remains in the extended period in regards to
the placement and timing of a slow moving (nearly cutoff) upper
level trough from the west and an area of low pressure working along
the southeast U.S coast. These two features combined with the
interaction of broad wedging high pressure off the northern New
England coast/southern Canadian Maritimes will influence how much
deep tropical moisture is funneling into the region.

As of now, have went ahead and increased shower and thunderstorm
chances (PoPs 30-50 percent), especially during the afternoon and
evening hours Wednesday through Friday as onshore flow increases
with the low pressure system just off the NC coast and an inverted
trough nearby. Have backed off the rain chances for the upcoming
weekend to around 15 to 30 percent. The 12z GFS/GEFS favors low
pressure coming up along the coastal Carolinas and into eastern
VA/Delmarva Friday into Saturday leading to increased shower and
thunderstorm chances during this time. The 12z ECMWF/EPS favors more
of the Thursday through Friday timeframe for tropical moisture as a
strong baroclinic zone sets up over the region. The ECMWF/EPS is
also more aggressive with high pressure wedging itself back into the
area for the upcoming weekend allowing precipitation chances to
decrease. The 12z Canadian is a blend of the two aforementioned
solutions above along with central guidance. It still carries heavy
probability of precipitation Thursday into Friday while lingering it
into the weekend.

With all said, specifics surrounding rain chances, amounts, and wind
will continue to remain uncertain until models can get a better grip
on the features at play. Increased onshore flow will remain leading
to seasonably normal to slightly below normal temperatures and
increased cloudiness throughout the extended period. Expect highs in
the 70s and 80s with lows in the 50s and 60s.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Light winds and mostly clear skies may result in some valley fog
late tonight. This could affect MRB, so have added an MVFR
mention for now. Fewer cumulus are expected Monday as low level
moisture thins, but mid and high level clouds will increase
toward evening. Winds will remain light and somewhat variable,
though generally between a northeast and southeast direction.

Moisture returns Tuesday along with an isolated shower west of a
line from MRB to SHD. Increasing easterly flow Tuesday night
could bring in sub-VFR CIGs and perhaps a little fog/drizzle.

Higher chances for lower CIGS look to occur Wednesday through Friday
as onshore flow increases further. In addition to the potential for
lower CIGS will be some temporary reductions during the
afternoons/evenings Wednesday through Friday as shower and
thunderstorm chances return. This is is due largely in part to an
upper level trough approaching from the west and area of low
pressure throwing tropical moisture into the region from the
southeast U.S coast. Highest chances for rain appear to be along and
west of the Blue Ridge. Winds change back to the west and southwest
Wednesday and Thursday next week.

&&

.MARINE...
No marine hazards are expected through Tuesday as high pressure sits
nearby. Sub-SCA level winds are expected out of the east and
northeast at less than 15 kts. SCA conditions look to return
Wednesday through Friday as onshore flow increase with low pressure
moving north from the southeast U.S coast. Shower and thunderstorm
chances will also return to the waters during this time.

&&

.TIDES/COASTAL FLOODING...
A Coastal Flood Advisory remains in effect for the shoreline of
Anne Arundel Co. for the overnight high tide cycle. However,
anomalies have trended down, and it`s possible water levels
remain just below minor flood stage.

Onshore winds remain through midweek as high pressure sets up over
the northeast CONUS. The east to northeast wind direction will
result in elevated tidal anomalies which could push the
sensitive tidal sites near minor flood stage. However, the
latest forecasts have trended down a bit, at least through
Wednesday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 6 AM EDT Monday for MDZ014.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...ADS/KRR
SHORT TERM...KRR/EST
LONG TERM...EST
AVIATION...ADS/KRR/EST
MARINE...KRR/EST
TIDES/COASTAL FLOODING...LWX