Severn, Maryland 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

319
FXUS61 KLWX 250759
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Fri Apr 25 2025

.SYNOPSIS...
High pressure will move to the offshore waters of the mid-
Atlantic Coast early this morning. A strengthening low pressure
system will approach from the west on Friday into Friday
night. This eventually pushes a cold front through the area on
Saturday afternoon. Canadian high pressure settles in on Sunday
into early next week. Another frontal system impacts the region
during the middle to latter half of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A weak area of high pressure will slowly push off the Mid-
Atlantic coast early this morning. Some passing high clouds are
noted on the GOES-16 nighttime microphysics channel. However, low-
level south to southeasterly flow is starting to moisten the
boundary layer. This is evident in some areas south of I-66
which are reporting scattered clouds around 2,000 to 2,500 feet.
Otherwise, a mild air mass remains in place with 3 AM
temperatures holding steady in the upper 40s to 50s.

Through the day, a residual diffuse warm front tracks across the
area. The most notable air mass change will be the marked uptick
in dew points. The added moisture in the column should help aid
in further cloud development through the day. Some shower
activity is likely to develop today, particularly west of U.S.
15 where scattered showers are in the forecast. Models show
rather nebulous upper support with relatively weak flow aloft.
However, the steady low-level warm advection should prove
instrumental to some of this shower development. The best chance
for any thunderstorms would be well west of the I-95 metros.
Overall temperatures will be mild as highs rise into the upper
70s, with 60s across the mountains.

High-resolution models bring scattered showers toward the I-95
corridor just after sundown. Forcing does improve later in the
evening as an upstream shortwave approaches from the central
Appalachians. An isolated rumble of thunder cannot be ruled
out into the overnight hours. Additionally, tonight should also
bring well above average temperatures owing to southerly winds
and thick cloud cover. Nighttime lows will likely be in the low
60s, closer to the mid 60s inside the Capital Beltway and in
Baltimore.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The first half of the weekend will again be warm, but with
continued opportunities for showers. Forecast high temperatures
are expected to again rise into the upper 70s to low 80s. The
parent cold front is set to slide through the area midday
Saturday. Some showers and thunderstorms are possible in advance
of this boundary, with some pop-up activity in the wake. The
guidance does show the core of the lower heights/cooler
temperatures aloft stays mainly north of the Mason-Dixon Line.
But some solutions do indicate a cluster of storms may develop
along and east of I-95, most notably the 00Z NAM nest. Any
convective activity should wind down after dark on Saturday
evening/night.

The other aspect of this system will be the gusty westerly
winds in the wake. Deep vertical mixing behind the cold front
should support gusty afternoon/evening winds with gusts up to 25
to 30 mph. Winds remain somewhat elevated into the night with
tight gradients formed by the offshore frontal system and high
pressure over the Great Lakes. Despite these winds, ample cold
advection will help usher lows into the 40s, with 30s along the
Allegheny Front. Any freezing temperatures are currently in
places where the growing season has not commenced yet.

A strong dome of Canadian high pressure settles over the area on
Sunday into Sunday night. This helps usher temperatures to near
average for late April. More specifically, this favors
widespread upper 60s to low 70s (mid 50s to mid 60s in the
mountains). Expect lots of sunshine with northwesterly breezes
around 15 to 20 mph. Model soundings show quite a bit of dry air
aloft, so would not be surprised to see humidity levels even
lower than in the forecast. Heading into Sunday night,
temperatures fall back into the 40s (mid/upper 30s for the
higher elevations). Winds should be much lighter as Canadian
high pressure will be overhead.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
High pressure will build overhead on Monday, leading to sunny skies,
light winds, and mild temperatures. High temperatures will be in the
70s for most.

High pressure will move offshore on Tuesday. Meanwhile, a potent
shortwave and associated area of low pressure will track
northeastward across the Western Great Lakes into Ontario/Quebec,
causing the system`s cold front to drop southeastward into the Ohio
Valley. A very warm airmass will advect into the area within
southerly flow at the surface and southwesterly flow aloft. High
clouds should be on the increase through the day, but temperatures
are still expected to make it well into the 80s. With high pressure
holding strong to our southeast, any storms are expected to remain
off to our northwest.

The aforementioned cold front will drop southward into our area on
Wednesday, leading to increasing chances for showers and
thunderstorms. Some of these storms could potentially be on the
stronger side, as surface based instability and appreciable deep
layer shear is present in most ensemble solutions. As flow aloft
flattens out and becomes more zonal in nature/parallel to the
orientation of the front, it may tend to stall out and become
stationary by Thursday. Ensemble guidance shows a significant amount
of spread with respect to the positioning of the front, with some
members showing it within our forecast area, while others progress
it off to our south. As a result, there`s considerable spread in the
temperature forecast for both Wednesday and Thursday. Locations to
the south of the front may reach 90 degrees, while locations further
north will likely only make it into the 60s or 70s.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Expect mainly VFR conditions today as high pressure departs off
to the east. Increasing low-level moisture may bring some
scattered low clouds to the I-95 terminals during the early
morning hours. While they may develop, it is not certain they
will move into the IFR range or not. However, will continue to
maintain a scattered 500 foot group until 14Z.

An increase in shower coverage is expected later this evening
which will likely bring some periods of MVFR conditions to the
area TAF sites. A few thunderstorms are possible, but confidence
is too low to introduce into the TAFs at this time.

On Saturday morning, ahead of strong cold front, a brief period
of enhanced low-level southerly shear moves through the area.
Eventually the cold front itself brings additional showers and
isolated thunderstorms to the region. In the wake, afternoon to
evening winds become gusty with westerly wind gusts to around
20 to 30 knots. This does come with VFR conditions which persist
into Sunday as Canadian high pressure builds in. Winds turn
more northwesterly on Sunday with afternoon gusts to around 20
knots.

VFR conditions and southerly winds are expected on both Monday and
Tuesday.

&&

.MARINE...
While current south to southeasterly winds are mainly 10 knots
or less, expect an increase in such winds later today. Southerly
channeling effects will aid in an increase in winds with gusts
up to 20 to 25 knots. Small Craft Advisories are in place
acrossall waters for this afternoon and early evening,
continuing everywhere outside the upper tidal Potomac into
tonight.

Showers and isolated thunderstorms move through later tonight
into Saturday, all in response to an approaching cold front.
Behind the cold front that moves through Saturday afternoon, an
increasingly gusty westerly winds overspreads the waters. This
will bring gusts to around 25 to 30 knots, which may include
occasional gale force winds at times. However, these will likely
be more sporadic in nature so no gale products are being issued
at this time. Small Craft Advisories are likely required for
the second half of Saturday into Sunday afternoon. Winds drop
off pretty quickly Sunday evening given the influence from
Canadian high pressure.

Sub-SCA level southerly winds are expected on Monday. Winds may near
low-end SCA levels within southerly flow on Tuesday.

&&

.TIDES/COASTAL FLOODING...
Tidal anomalies currently range from 0.25 to 0.50 feet this
morning. There will be some uptick in water levels ahead of a
cold front that tracks through Saturday afternoon. The current
forecast brings Annapolis into Action stage, but all others
remain below. Behind the front, a west to northwesterly wind
will quickly lower anomalies across the area. No tidal flooding
is expected on Sunday into Monday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory from 2 PM this afternoon to 6 AM EDT
     Saturday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 6 AM EDT
     Saturday for ANZ530>534-536>543.
     Small Craft Advisory from 2 PM this afternoon to 8 PM EDT this
     evening for ANZ535.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KJP
AVIATION...BRO/KJP
MARINE...BRO/KJP
TIDES/COASTAL FLOODING...BRO