247
FXUS61 KLWX 141322
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
922 AM EDT Mon Apr 14 2025

.SYNOPSIS...
A cold front will cross the region this evening bringing some
strong to severe thunderstorms. Windy conditions are expected
Tuesday in wake of the cold front. A reinforcing cold front will
move through early Wednesday, then high pressure will build
toward the area to end the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A strong upper trough over the Upper Plains/Great Lakes will
swing through the Midwest/OH Valley today into tonight. Ahead
of this system, a leading shortwave trough and its associated
surface cold front are expected to move across the OH Valley to
Mid-Atlantic through tonight. At least scattered thunderstorms
that develop along the front move across the Alleghenies late
this afternoon, then into the I-81 corridor toward I-95 this
evening. Multiple clusters of strong to severe thunderstorms are
possible as the front moves through this evening. Latest trends
suggest the highest potential for severe wind gusts may be with
a linear feature near the I-64 corridor from 7-10 PM, though
some hail is possible just about anywhere given steepening mid-
level lapse rates.

As of mid morning, clouds were attempting to clear from west to
east. Conditions are expected to remain dry for most of the
day, with showers/storms approaching the Alleghenies probably
around or shortly after 5-6PM.

A warm front is forecast to move north through the area today,
bringing with it warmer temperatures and increasing low-level
moisture. However, even now there remains some uncertainty in how
far north the front makes it. While most of 00Z/06Z guidance
shows the front making it to the MD/PA border, there are still a
few models that keep the front around the Potomac River or near
I-66. This leaves uncertainty in the amount of instability that
develops across the northern portions of the CWA. To the south
of the front, temperatures are expected to warm quickly into
the 70s this afternoon with low 80s in parts of central VA. Dew
points reach the low to mid 50s by late afternoon.

Generally expecting favorable conditions for some clusters of strong
to severe thunderstorms to move across the area this evening. The
entire area will be overspread with 60-65 kt of deep layer shear and
steep mid-level lapse rates (due to a passing EML). Model soundings
indicate MLCAPE values of 600-1200 J/kg reaching the I-81 corridor,
and 500-800 J/kg east of the Blue Ridge to I-95. Due to backed low-
level flow and increasing winds aloft, 0-3km SRH values approach 200-
300 m2/s2 across most of the area this evening. This could provide a
small window for a tornado or two to develop, though the greatest
chance for that will be west of the Blue Ridge. Otherwise,
supercells and line segments will be capable of producing damaging
wind gusts and large hail.

As the front moves through the area, it is forecast to flatten and
slow down tonight. This could keep showers in the forecast
along/south of I-66 and along/east of I-95. Mild conditions tonight
as lows settle in the 50s to low 60s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
The strong upper trough digs over the area Tuesday, with the surface
pressure gradient tightening in response to the deepening low to our
north. Winds are expected to increase quickly after sunrise, with
the highest gusts during the early to middle afternoon. This is when
the main upper trough moves overhead, with a potent 100kt jet streak
at 500mb and 120-130kt at 250mb. The nearly unidirectional deep
westerly for is a favorable setup for strong winds aloft to mix down
to the surface. Wind gusts are forecast to be around 35-50 mph
for most of the area, with 45-55 mph gusts in the mountains.

As a result, a Wind Advisory has been issued for the Alleghenies and
portions of the Shenandoah Valley where confidence in wind gusts of
45-55 mph are highest. If model trends continue, the Wind Advisory
will likely be expanded across most of the rest of the CWA.

Compressional warming brings highs up to the 60s Tuesday afternoon.
More clouds than sun can be expected Tuesday with isolated to
scattered showers beneath the trough. While the area dries out by
Tuesday evening, cold air advection in the mountains results in a
transition to snow showers Tuesday night. Upper dynamics look
favorable on the backside of the departing upper trough, with
northwest winds advecting moisture off the Great Lakes. Snow will be
elevation dependent as the atmosphere slowly cools, with generally
an inch or less of accumulation most likely. However, the higher
ridges could see a few inches if higher precipitation guidance were
to verify. East of the mountains, lows range from the mid 30s to mid
40s with gusty winds continuing.

Mountain snow showers come to an end Wednesday morning. Otherwise,
dry and gusty conditions are expected Wednesday in the wake of
a cold front. West winds gust 25 to 35 mph during the day, with
locally higher gusts along the ridges. Wednesday is likely the
coolest day this week as highs only reach the 50s to low 60s,
with 40s in the mountains. Overnight low temperatures fall into
the 20s and 30s as winds diminish throughout the night. Freeze
Watches/Warnings may be needed for parts of the Shenandoah
Valley where the growing season has begun.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Longwave upper ridge will build over the East during the second half
of the week promoting a significant warming trend and dry
conditions. A northern stream disturbance and associated cold front
will move across the area Sat night bringing a chance of showers and
possible thunderstorms Saturday into Sat evening. Low-level ridging
builds again for Sunday. Temperatures will remain well above normal
during the entire long term period, except Sun when there will be a
brief cooldown.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
VFR conditions expected today as a cold front approaches from the
west this evening. Numerous showers and scattered thunderstorms are
expected to move across the region this evening, with a few severe
thunderstorms possible. TEMPO groups have been added to IAD, DCA,
BWI, MTN, and MRB where confidence in seeing impacts has increased.
CHO remains with a PRO30 group for thunderstorms, though a TEMPO
will likely be added by the 18Z TAF package due to increasing
confidence. Any strong to severe storm will be capable of
producing wind gusts in excess of 35-45 knots and lightning
strikes.

Showers and thunderstorms come to an end late this evening, though a
few showers could linger near DCA/BWI/MTN through the night.

Dry conditions Tuesday and Wednesday behind the cold front with VFR
conditions expected. Windy conditions are likely Tuesday as west
winds gust around 30-40 knots from late morning through late
afternoon. Winds remain elevated at 20-25 knots Tuesday night, then
increase to 25-30 knots from the northwest on Wednesday. Winds
finally diminish Wednesday night.

Gusty NW winds up to 20 kt are expected Thu, strengthening to 25 kt
Fri.

&&

.MARINE...
Favorable marine conditions through this afternoon in generally
light south winds around 5-10 knots. By this evening, southerly
channeling is expected to bring winds close to SCA conditions in the
Chesapeake Bay. A Small Craft Advisory may be needed for portions of
the waters if confidence increases.

Additionally, scattered strong to severe thunderstorms are expected
to move across the local waters this evening. Special Marine
Warnings are likely needed as these storms will be capable of
producing wind gusts in excess of 40 knots and large hail. While
most of the thunderstorm activity wanes around midnight, some could
linger through the overnight.

The cold front sweeps through late tonight and ushers in a two
day period of hazardous marine conditions. West winds quickly
increase Tuesday morning through Wednesday night. Gale
conditions are becoming likely for most of the waters Tuesday
from late morning to the afternoon. Thus, the Gale Watch has
been expanded to cover all of the waters. After that, winds
remain elevated (20-30 kt gusts) through Wednesday night.

SCA conditions are expected through Thu, then again Friday into
Saturday.

&&

.TIDES/COASTAL FLOODING...
Annapolis is forecast to reach action stage, and near minor flood
stage, during the high tide cycle today and Tuesday morning due
to southerly winds. Gusty northwest winds are expected in the
wake of a cold front on Tuesday, with tidal anomalies expected
to fall.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Wind Advisory from 10 AM to 8 PM EDT Tuesday for MDZ501-502-
     510.
VA...Wind Advisory from 10 AM to 8 PM EDT Tuesday for VAZ025>027-
     029-504-507-508.
     Wind Advisory from 10 AM Tuesday to 8 AM EDT Wednesday for
     VAZ503.
WV...Wind Advisory from 10 AM to 8 PM EDT Tuesday for WVZ050-055-
     502>504-506.
     Wind Advisory from 10 AM Tuesday to 8 AM EDT Wednesday for
     WVZ501-505.
MARINE...Gale Watch from Tuesday morning through Tuesday evening for
     ANZ530>543.

&&

$$

SYNOPSIS...DHOF/KRR
NEAR TERM...DHOF/KRR
SHORT TERM...DHOF/KRR
LONG TERM...LFR
AVIATION...LFR/DHOF/KRR
MARINE...LFR/DHOF/KRR
TIDES/COASTAL FLOODING...LWX