035
FXUS61 KLWX 260800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Sat Apr 26 2025

.SYNOPSIS...
As low pressure tracks across interior New England, a cold front
will move through the area this afternoon and evening. Canadian
high pressure will settle in on Sunday into Monday before moving
offshore. Another frontal system will affect the region during
the middle of next week before meandering nearby into Thursday.
This system eventually moves through the area by Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The early morning frontal analysis places a warm front lifting
northward away from the Mid-Atlantic. At the same time, an
upstream cold front continues to churn eastward from central
Ohio back down into western portions of Kentucky and Tennessee.
This configuration puts the local area squarely within an
expanding warm/moist sector. Consequently, 07Z/3 AM surface
observations are seasonably moist with dew points in the upper
50s to mid 60s. Given a nearly saturated atmosphere in place,
temperatures are largely in the low/mid 60s which is well above
average for late April.

On the radar, a bulk of the earlier convective activity has
moved off to the east into Delaware and southern New Jersey.
Some isolated showers are occurring in the wake across central
Virginia. However, radar trends suggest a brief dry period ahead
of the next round of activity set for the late morning to
afternoon hours.

The main feature of interest is a strong closed low spinning
over southern Ontario, with a mean longwave trough extending
southward into the Upper Great Lakes region. Although the core
of lower heights/cooler air aloft will stay north of the Mason-
Dixon Line, the height falls alone should help spawn scattered
to numerous showers across the area. Any threat for
thunderstorms will largely be tied to the cold front itself,
especially as it moves east of U.S. 15. Convective-allowing
models from 00Z and 12Z (yesterday) continue to show a slew of
40 dBZ echoes per paintball plots.

Given the moisture in place combined with cooling temperatures
aloft, there should be around 1,000 J/kg of surface-based CAPE
to work with, particularly along and east of I-95. Vertical
shear profiles are somewhat marginal, generally averaging 25 to
30 knots in the 0-6 km layer. The net of all these factors
should support at least an isolated severe thunderstorm or two
this afternoon/evening. The main threat would be damaging wind
gusts although an isolated severe hailstone cannot be ruled out.
Any convective threats should wind down by just after dark.

On the temperature side, today will provide another warm day
with highs rising into the mid 70s to low 80s (60s across
mountain locales). The mentioned cold front will aid in shower
and thunderstorm development, but also a shift to gusty westerly
winds in the wake. Expected gusts will largely range from 25 to
30 mph, locally up to 35 mph over the higher terrain. Winds
remain elevated into the overnight hours although the cold
advection pattern will still usher low temperatures down into
the 40s, with mid/upper 30s across the mountains.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Winds remain breezy in nature while gradually shifting from
westerly to northwesterly. The continued cold advection regime
will make for a cooler finish to the weekend. Despite the cool
down, temperatures do stay fairly close to climatology with
highs in the mid 60s to low 70s. The net gradient formed by the
offshore cold front and Canadian high pressure over the Great
Lakes will maintain gusty winds through much of the day.
Forecast gusts should again push into the 25 to 30 mph range,
but this comes with a dry forecast and sunny skies.

This dome of Canadian high pressure arrives Sunday evening
before settling overhead early Monday. Radational cooling
effects should be more prominent on Sunday night owing to light
winds and clear skies. Low temperatures are likely to fall into
the upper 30s to 40s, with slightly cooler conditions over
mountain locations.

After a brief cool down, high pressure gradually exits the
Atlantic coast on Monday which allows for a return flow to
ensue. This helps bump temperatures back up a bit with highs
returning to the low/mid 70s. Skies will again remain sunny
given subsidence in the column. Southerly winds help raise
temperatures into the overnight period as well with lows holding
steady in the upper 40s to mid 50s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
High pressure will progress offshore on Tuesday as low pressure
tracks well off to our northwest through the Upper Great Lakes into
Ontario/Quebec. The system`s trailing cold front will drop southward
into the Ohio Valley. Southerly flow at the surface behind the
departing high and southwesterly flow at 850 hPa will transport a
much warmer airmass into the area, with high temperatures expected
to reach well into the 80s. Increasing low-level moisture and
glancing height falls as the system passes to our northwest may lead
to the development of some afternoon showers and thunderstorms
across western Maryland or the West Virginia Panhandle, but most
locations are expected to remain dry.

Low pressure is expected to rapidly track eastward across Quebec on
Wednesday, with high pressure building to our north in its wake.
This will push the aforementioned cold front southward through our
area before the front eventually stalls out (likely to our south).
Ensemble guidance still shows some uncertainty in the positioning of
the front, but most solutions place it across southern portions of
our area or off to the south. This uncertainty in the placement of
the front leads to uncertainty with respect to forecast
temperatures, as well as chances for showers and thunderstorms.
Locations to the south of the front will likely make it into the 80s
to near 90, while locations further north will only make it into
the 60s and 70s. Chances for showers and thunderstorms look to be
relatively low, but increase the further south you go (since they
have a better chance of ending up near the stalled front).

Most guidance suggests that a trough will move northeastward from
the Desert Southwest toward the Great Lakes Thursday into Friday,
potentially phasing with a shortwave in the northern stream tracking
southeastward out of the Canadian Prairie Provinces. As the
resultant area of low pressure tracks to our northwest, this should
cause the stalled front to our south to return northward as a warm
front, leading to an uptick in temperatures and low-level moisture.
With that increasing moisture, chances for afternoon showers and
thunderstorms will also increase moving into Thursday, and
especially Friday. Many solutions show an appreciable overlap of
CAPE and shear locally on Friday, suggesting that some stronger
storms could be possible. However, uncertainty remains high this far
out.


&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
While most locations are remaining VFR early this morning, the
saturated nature of the atmosphere is bringing occasional IFR
ceilings to TAF sites. However, these instances of IFR
conditions appear to be more transient in nature. Another round
of showers begins to move through during the late morning to
afternoon hours. Any threat for thunderstorms would be in the
17Z-21Z period and focused over the Baltimore and D.C.
terminals. Will maintain the PROB30 groups at these sites, with
more details likely added as confidence increases. Restrictions
are possible as these storms roll through.

A cold front responsible for this convective activity will bring
a shift to gusty westerly winds in the wake. This also comes
with a return to VFR conditions which continue through the
remainder of the weekend into Monday. Winds remain gusty through
much of the weekend while shifting from westerly to
northwesterly by Sunday. As Canadian high pressure moves in
Sunday evening into Monday morning, expect much lighter winds
over the area. As this ridge exits the Atlantic coast, winds
return to southerly on Monday.

VFR conditions and southerly winds are expected on Tuesday.
Prevailing VFR conditions should continue into Wednesday. Winds will
likely shift to out of the northwest on Wednesday, but some
uncertainty remains regarding the positioning of a front and the
resultant wind direction locally.

&&

.MARINE...
A breezy south to southeasterly wind has maintained small craft
conditions over the area waters. Outside of the upper tidal
Potomac, all marine sites are currently in Small Craft
Advisories. As winds increase in strength this morning, all
locations will be in such advisories through tonight.

A strong cold front tracks across the area waters later this
afternoon into the early evening. This may prompt the need for a
Special Marine Warning or two. Behind these storms, a gusty
west-northwesterly wind is expected with forecast gusts around
30 knots. Models continue to hint at near gale force winds
during the evening to overnight period. Will determine if any
upgrade is needed to Gale Warnings.

Small Craft Advisories will likely be needed for much of Sunday
before winds drop off as Canadian high pressure moves in. Sub-
advisory caliber winds are expected on Monday as southerly flow
ensues.

Winds may near low-end SCA levels within channeled southerly flow on
Tuesday. Winds are expected to shift to out of the northwest on
Wednesday, but some uncertainty remains regarding the positioning of
a front and the resultant wind direction locally.

&&

.TIDES/COASTAL FLOODING...
There will be some uptick in water levels ahead of a cold front
that tracks through this afternoon. The current forecast brings
Annapolis and Baltimore 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 until 6 AM EDT Sunday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for ANZ530>534-
     536>543.
     Small Craft Advisory from 11 AM this morning to 6 AM EDT
     Sunday for ANZ535.

&&

$$

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

NWS LWX Office Area Forecast Discussion