825
FXUS61 KLWX 280759
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Fri Jun 28 2024

.SYNOPSIS...
High pressure builds in from the west today before pushing
offshore late tonight into Saturday morning. A warm front lifts
through the region on Saturday which will bring showers and
thunderstorms back to the region. A cold front will then push
through on Sunday, bringing yet another chance for afternoon
showers and thunderstorms. High pressure then returns for the
early portion of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A quick-moving area of high pressure passes to our north today,
moving offshore by late tonight. Dry conditions are expected
during the day, but some showers could develop in the late in
the evening along terrain in the Shenandoah Valley and Blue
Ridge as the center of high pressure swiftly moves offshore and
a shortwave approaches from the northwest. With southerly flow
behind the exiting high pressure, the influx of moisture will
likely bring some decent fair weather cumulus. Temperatures
look relatively cooler, topping out in the upper 80s. Lows hover
in the 60s to mid 70s with cloud cover increasing overnight.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As high pressure moves offshore, south/southwesterly return
flow will usher in a warmer, more humid air mass for Saturday.
Temperatures Saturday still look hot, but moisture has trended
down in guidance somewhat with lower Td and PWATs, so it seems a
less oppressive heat. Temperatures are currently forecast to
top out in the upper 80s to low 90s, with dewpoints in the low-
mid 70s in the afternoon. Apparent temps will approach 100 in
some locations east of the Blue Ridge.

Showers and thunderstorms, including severe potential, will be
the main story of the weekend. The warm front is expected to
lift through Saturday morning into early afternoon. Some showers
could develop with this, but most will likely be restricted to
terrain of the Blue Ridge and Alleghenies. As we cross into the
warm sector, severe potential increases with any storms that do
develop. Coverage of storms will increase west to east through
the afternoon with a prefrontal trough ahead of the approaching
cold front. SPC has extended the Slight to include our northwest
zones (western MD, WV panhandle), along with a 2% TOR prob
extending another tier or two of counties south and east of the
Slight. By the afternoon and evening, the area can expect
1000-1500 J/kg of CAPE, with the greatest instability focused in
two corridors: 1) west of the Blue Ridge 2) along the
Chesapeake. Shear will be most favorable in the 1st throughout
Saturday, but the 2nd will see a favorable environment by the
evening. Timing of the approaching cold front and lee trough in
relation to the loss of daytime heating will be key. Severe
threat could extend into the overnight, especially along our
mountain west.

Currently the cold front is progged on our western doorstep by
Sunday morning, making its way through the area by the evening.
It will be a similar story to Saturday, and SPC currently has
most of the area east of the Blue Ridge highlighted in a Slight
for Day 3. This makes sense, as the front is expected to be
moving through this portion of the area during peak heating.
Severe potential Sunday will, as it often is, be dependent on
prior convection. As it stands now, it appears with two
different areas of focus Saturday and Sunday that we might not
be worked over for Sunday, but there is still the potential for
cloud debris limiting instability. We`ll continue to monitor the
weekend severe threat as we grow closer.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A positively-tilted longwave trough will push off the Eastern
Seaboard on Monday. The associated cold front is expected to settle
further offshore while a strong area of high pressure pushes in from
the Great Lakes. Forecast models depict surface pressures around
1024-mb which is fairly impressive for the start of July.
Considering the typical climatology, this is approximately 1.5 to 2
sigma above average. The result of this anomalous ridge will be
below average temperatures and low humidity levels. Monday`s
forecast highs are expected to range from the upper 70s to low 80s,
accompanied by dew points in the upper 40s to mid 50s. Sunny skies
will give way to a clear night as the surface high becomes centered
over the northeastern U.S. Optimal radiational cooling effects
should be in place which yields nighttime lows in the 50s to low
60s, locally into the mid 60s along and east of I-95.

The trough which moves offshore is expected to cut off and settle
well east of New England. At the same time, 500-mb heights rise by
around 10 dm heading into Tuesday as a southern to southeastern U.S.
ridge expands northward. While the forecast stays dry, a slow warm
up begins to ensue as highs push back into the mid 80s. Dew points
stay in the 50s as winds meander between north to northeasterly.
Eventually a surge in moisture is likely as winds turn southeasterly
by Tuesday evening and into the night.

A return to summertime weather comes on Wednesday through
Independence Day, possibly longer depending on when a cold front
tracks through. Based on the latest WPC frontal forecast, the
forward progress of the system halts near the Appalachians
before stalling off to the north. The multi-ensemble temperature
spread supports this continued period of near to above average
temperatures. As this common in the warm season, the heat and
humidity will increase the overall threat for diurnal
convection. The chances for showers and thunderstorms seem to
increase heading through the Independence Day holiday and into
Friday.

It is difficult to say when additional relief comes from the stretch
of hot weather during the mid/late week period. The Climate
Prediction Center`s Week 2 hazards outlook continues to monitor the
threat for more heat heading into the weekend.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Mostly dry conditions follow and continue into Friday as high
pressure passes to the north. Winds early in the day will be
5-10 knots out of the NE before slowly turning out of the SE by
the afternoon.

Onshore flow Friday night into Saturday morning could bring some
lowered CIGs along/east of the Blue Ridge, which could
particularly impact CHO. Lowered VSBY is possible, but winds are
expected to be prominent enough to keep fog threat pretty low.

Sub-VFR conditions are likely Saturday with any showers and
thunderstorms that move across the terminals. A warm front lifts
through the area in the morning/afternoon with some shower
activity expected, and more is expected in the afternoon and
evening with the potential for strong to severe storms. Sub-VFR
continue into Sunday with showers and thunderstorms expected
with a cold frontal passage, though likely improve behind the
cold front.

VFR conditions are likely for Monday and Tuesday underneath an
anomalously strong surface high. Northerly gusts up to 15 to perhaps
20 knots are possible on Monday. As the high passes to the north,
winds begin to shift over to east/northeasterly on Tuesday before
turning more southeasterly later in the day.

&&

.MARINE...
As flow has turned out of the NE with high pressure moving east,
a pressure surge has been observed over the waters, resulting in
SCA conditions. SCAs are in effect until late morning.

As winds increase out of the SW, SCAs may be needed this
evening and again with strengthening southerly flow and a
passing warm front on Saturday. Additionally, any storms that
develop Saturday could produce damaging wind gusts and need
SMWs. There is a non-zero threat for waterspouts as well. Both
of these threats seem greatest in northern portions of the
waters at this time.

With northerly flow on the eastern side of the sprawling ridge of
high pressure, channeling effects are likely across wider waters of
the Chesapeake Bay on Monday. This may necessitate Small Craft
Advisories before winds diminish in strength heading toward sundown
on Monday evening. Winds should stay below advisory thresholds
through Tuesday with eventual shifts to northeasterly and then
southeasterly as the high passes to the north.

&&

.TIDES/COASTAL FLOODING...
With prevailing north to northeasterly winds, tidal anomalies remain
low as they current average between 0.20 to 0.50 feet. Today`s winds
shift to mainly east-southeasterlies which allow some rise in water
levels. A large rise ensues over the weekend give the stretch of
southerly flow. A number of tidal sites start to push into Action
stage, with Annapolis and Havre de Grace currently forecast to hit
Minor late Saturday night/early Sunday. Expect a cold front to track
through Sunday evening which helps usher much of the additional
water back toward the south heading into the new work week.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for
     ANZ530>533.
     Small Craft Advisory until 11 AM EDT this morning for ANZ534-
     537-543.

&&

$$

SYNOPSIS...EST/CAS
NEAR TERM...CAS
SHORT TERM...CAS
LONG TERM...BRO
AVIATION...BRO/CAS/CJL
MARINE...BRO/CAS/CJL
TIDES/COASTAL FLOODING...BRO