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000
FXUS61 KLWX 160757
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
357 AM EDT Tue Apr 16 2024

.SYNOPSIS...
A cold front will drift to the south today before stalling near the
Virginia/North Carolina border. This boundary returns northward as a
warm front on Wednesday. A weak cold front tracks through on Thursday
before a stronger cold front arrives early in the weekend. High
pressure returns on Sunday and into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The latest surface observational datasets indicate the cold front
has slowly pushed south of I-66/U.S. 50. This is most evident in the
increase in northerly winds in the wake of the frontal passage. A
couple hour period of 20 to 25 mph gusts are possible as this system
continues its southward trek toward the I-64 corridor. While
temperatures are very mild right now with most reporting
readings in the 60s, there is a notable dew point fall as this
boundary tracks through. 3-hour falls are on the order of 15 to
20 degree dew point drops. This southward push is expected to
persist through this afternoon before the system stalls near the
Virginia-North Carolina border.

In the wake of this frontal passage, expect a cool down relative to
the 80 degree plus readings observed on Monday. Low to mid 70s are
likely across a vast majority of the area. Have opted to lower dew
point/humidity levels given the likelihood that dry air at the top
of the mixed layer reaches the surface.

Heading into the afternoon to evening hours, showers and isolated
thunderstorms are expected across the Allegheny Highlands toward the
Shenandoah Valley. Most high-resolution models do not show instability
pushing too far east off the Allegheny Front. Thus, expect the
main convective chances to focus over the higher terrain. Severe
weather threats appear a lot lower given weaker shear profiles
and somewhat questionable forcing mechanisms. Shower activity
edges eastward through the evening before mainly waning
overnight. Expect seasonably mild night conditions at night with
low temperatures in the low/mid 50s. This is roughly 10 to 15
degree above mid-April climatology.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
On Wednesday morning, the warm front is expected to stretch from
northwest to southeast across the area. Its northward
progression appears sluggish at times as the system struggles
to reach the Mason-Dixon Line on Wednesday. Given this artifact
of the forecast, locations to the north will likely see a cooler
day than those south of I-66. The latest forecast package
depicts mainly low to mid 70s across the region, while mid/upper
60s are more commonplace along I-70 and points northward. The
warm sector should have the best chances for any convective
activity, with rain showers being likely over most of the area.
Weak height falls aloft coupled with increasing low-level warm
advection should allow for greater convective coverage than
Tuesday. Although northeastern Maryland remains in the cool
sector through this evening and night, some elevated convection
is possible as indicated in the forecast package. Nighttime
conditions will stay mild with lows in the 50s.

Heading into Thursday, the shortwave responsible for the
previous day`s activity is forecast to track up into New England
and southern Quebec. A weak/diffuse cold front will track
through the region on Thursday leading to a shift to north-
northwesterly winds. Shortwave ridging in the wake should help
temper some of the shower chances. However, will maintain around
a 20 to 30 percent chance through the day. Do expect a vast
majority of the day to be dry, accompanied by a mix of clouds
and sun. Locations in central Virginia should see more sunshine
which will favor high temperatures rising into the upper 70s to
low 80s. On the converse are the Allegheny Front and
northeastern Maryland which each may be confined to the 60s.
Winds shift to east to northeasterly overnight with lows falling
into the mid 40s to low 50s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Upper ridging will be departing off the coast Friday while a cold
front approaches from the west. While timing and placement of
features still have some uncertainty, it appears the cold front will
push into/through the area Friday or Saturday, representing the
highest chances for rain showers. A relatively stable atmosphere and
lack of rich moisture will keep thunderstorm chances to a minimum.
The front won`t push to the southeast very fast, and there is some
potential for a wave of low pressure to ride along the boundary and
produce additional rain chances over the weekend. While not zero,
rain chances decrease by Monday as there is some consensus for high
pressure to build in from the west.

Temperatures Friday and Saturday may depend somewhat on cloud cover
and rainfall, but have potential to remain above normal. The greater
signal for cooler (near or below normal) temperatures arrives Sunday
and Monday as upper troughing pushes east of the area.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
A slow moving cold front will continue to drop southward through
the area today. In the wake, winds shift to mainly north to
northeasterly. However, this is likely to be short lived as this
frontal system eventually returns northward as a warm front
later today. Expect mainly south to southeasterly winds the
second half of the day and into tonight. The main shower chances
should stay west of the terminals although did include a VCSH
line in the KCHO TAF between 7-11 PM. Otherwise, VFR conditions
are in store for the terminals.

Shower and thunderstorm chances increase on Wednesday as the
warm front tracks northeastward across the area. The best chance
for thunder would be at KCHO, KMRB, KDCA, and KIAD. It is
difficult to say how far north this system is able to track.
Regardless of convective threats, rain showers are likely on
Wednesday which will lower ceilings into the MVFR to near IFR
ranges. MVFR to IFR conditions linger into Wednesday night
across the Baltimore terminals. By Thursday, although a few
showers are possible, expect mainly VFR conditions along with
northwesterly winds. These shift to northeasterly overnight.

Sub-VFR conditions are possible at times Friday and Saturday as
a cold front brings potential low ceilings and rain showers.

&&

.MARINE...
Given enhanced northerly gusts behind the slow moving cold
front, Small Craft Advisories are in place until 6 AM this
morning for the wider Chesapeake Bay waters. Gusts of 20 to 25
knots have already been observed and will continue the next
couple of hours. Wind fields stay below advisory levels through
Thursday morning before ramping back up on Thursday
afternoon/evening behind a cold front. Some portions of the
waters may need Small Craft Advisories with this surge. Such
winds gradually weaken into late Thursday night.

Convective threats mainly focus on Wednesday into Wednesday
night as a warm front pushes northeastward across the area.
Special Marine Warnings would be needed for any of the more
robust activity. The atmosphere looks more stable on Thursday as
a cold front pushes through the region.

Onshore flow likely remains below SCA criteria Friday. A cold front
will likely push to the south Saturday, and SCA conditions will be
possible in WNW flow in its wake.

&&

.TIDES/COASTAL FLOODING...
While some action stages may be reached through the middle of
the week, the greater water level rises and potential for near-
minor flooding appears to be toward Friday as onshore flow
develops ahead of a low pressure system.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for
     ANZ531>534-538.

&&

$$

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