519
FXUS61 KLWX 041357
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
957 AM EDT Sat May 4 2024

.SYNOPSIS...
A stalled frontal boundary will remain draped to the south of
the forecast area throughout the weekend, bringing on and off
showers and possible thunderstorms. A secondary cold front will
move through the area on Monday before lifting as a warm front
on Tuesday. This will bring a prolonged period of unsettled
weather through next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The cold air damming wedge signature is well in place per recent
surface observations. The latest frontal analysis places this
boundary down in central North Carolina arcing back into eastern
Kentucky. Low-level easterly flow will ensure a cool damp day,
accompanied by overcast skies, drizzle, and passing rain showers.
Have opted to further lower today`s high temperature forecast
which keeps most spots in the mid/upper 50s. Perhaps a 60 degree
reading or two are possible across central Virginia and far
southern Maryland.

These cooler and more stable conditions combined with plenty of
cloud cover will hinder thunderstorm development. Given this
assessment, any threat for thunder appeared minimal enough to
remove from the forecast today. WPC has the westernmost
portions of the forecast area in a marginal risk for excessive
rainfall. Isolated instances of flooding are possible, though
dry antecedent conditions and 24-hour QPF values less than an
inch will lead to most of the rainfall being beneficial.

Heading into the overnight hours, rain showers will persist and
become more steady in nature. Moisture aloft will deepen
overnight, leading to periods of heavier rain. Nighttime low
temperatures will be in the upper 40s to 50s areawide.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The aforementioned cold front stalled to our south, will lift
through the forecast area on Sunday. This will bring noticeably
warmer temperatures with highs in the 60s to low 70s throughout
the area. Additionally, rain shower and thunderstorm chances
will continue both Sunday and Monday. Thunderstorm chances will
peak in the afternoon as instability increases with SPC having
the forecast area in a general thunder risk each day.

High temperatures will continue to warm on Monday due to
southerly flow ushering warm air. High temperatures will be in
the 70s to low 80s areawide. Those at highest elevations will
stay in the upper 60s throughout the day. Overnight low
temperatures will stay in the upper 50s to low 60s each night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Conditions will remain active through the long term period. A potent
shortwave trough and associated area of low pressure will track
across the Upper Midwest toward the western Great Lakes on Tuesday,
and then across southern Ontario/Quebec on Wednesday. A surge of
warm/moist advection will ensue at low levels in response on Tuesday
as a warm front lifts northward through the area. Afternoon showers
and thunderstorms appear likely on Tuesday in response to the
combination of daytime heating and low level warm/moist advection on
the synoptic scale. High temperatures on Tuesday should reach into
the upper 70s and lower 80s.

Low-level forcing for ascent decreases somewhat on Wednesday as we
move into the open warm sector and low-level flow turns westerly.
Thunderstorms will be possible again Wednesday afternoon, but the
coverage of storms should be considerably lower than Tuesday. In
westerly low-level flow, a lee trough may serve as a potential focus
for the development of storms. It will be noticeably warmer on
Tuesday, with high temperatures expected to be in the mid-upper 80s.

A prominent shortwave will eject eastward from the Plains toward the
Ohio Valley/Great Lakes on Thursday. An associated area of low
pressure will track toward the northern Ohio Valley toward PA and NY
by Thursday evening. This system will act to increase large scale
forcing for ascent across the area, while also strengthening the
wind field through the low-mid levels. As a result, showers and
thunderstorms are expected again Thursday, some of which may be
strong to severe in nature. High temperatures on Thursday are
forecast to reach into the upper 70s to mid 80s.

Model solutions begin to diverge by Friday, with some models driving
a cold front southeastward through the region Thursday night, while
others hold off on the frontal passage until Friday night. As a
result, a wide range of potential forecast outcomes exist. If we`re
post cold frontal on Friday, we`d have much cooler temperatures, and
dry conditions. However, if the front remains upstream of the area,
we`d have another day with warm and humid conditions, as well as
additional chances for showers and thunderstorms.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Onshore flow will bring reduced ceiling heights and plenty of
cloud cover throughout the day today. MVFR to IFR conditions
are expected throughout the day as a stalled frontal boundary
continues rain and drizzle through the overnight. Winds remain
out of the east with gusts staying 10-15 knots possible at all
terminals except for CHO, where winds will remain lighter.
Tonight, heavier precipitation rates may lead to sub-IFR
conditions.

Precipitation and thunderstorm chances continue Sunday with IFR
flight conditions expected throughout the morning. Flight
conditions possibly improve to MVFR Sunday afternoon, through
dense fog and reduced CIGs could bring renewed chances for
IFR/sub-IFR conditions. Winds shift to southeasterly on Sunday,
blowing less than 10 knots. Unsettled conditions continue as we
head into the week as a cold front approaches from the west.

Prevailing VFR conditions are expected on Tuesday and Wednesday, but
temporary drops to sub-VFR conditions may be possible in any
thunderstorms. Winds will generally be out of the east on Tuesday,
before turning out of the south Tuesday night into Wednesday.

&&

.MARINE...
A Small Craft Advisory remains in effect through tonight for
the Chesapeake Bay with east winds blowing 10 to 20 knots.
Gusts up to 25 knots are possible. Winds increase for the Upper
Potomac and Upper Chesapeake Bay tonight, with SCA conditions
expected. Showers and perhaps a thunderstorm are expected
throughout the weekend as a warm front moves over the waters and
a cold front approach from the west. Winds shift to southerly
on Sunday and are expected to remain below SCA criteria as we
head into the week.

Sub-SCA level winds are expected in easterly flow on Tuesday, and
then in southerly flow Tuesday night into Wednesday. SMWs may be
possible either day if thunderstorms pass over the waters.

&&

.TIDES/COASTAL FLOODING...
Anomalies have continued to rise this morning amidst easterly
onshore flow. Current anomalies are running between 1.25 and
1.75 feet. This regime is expected to persist into tonight
before winds turn out of the south to southeasterly on Sunday.
Tides are expected to remain elevated through the weekend, with
Minor flooding possible in many locations. Moderate flooding may
also be possible at Annapolis and Straits Point, where a
Coastal Flood Watch is in effect for tonight. Water levels may
begin to decrease during the day Monday as winds turn
southwesterly.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Advisory from 4 PM this afternoon to 9 AM EDT
     Sunday for DCZ001.
MD...Coastal Flood Advisory until 5 PM EDT this afternoon for
     MDZ014.
     Coastal Flood Warning from 11 PM this evening to 8 AM EDT
     Sunday for MDZ014.
     Coastal Flood Advisory until 2 PM EDT this afternoon for
     MDZ016-017.
     Coastal Flood Warning from 8 PM this evening to 4 AM EDT
     Sunday for MDZ017.
     Coastal Flood Advisory until 3 AM EDT Sunday for MDZ018.
VA...Coastal Flood Advisory from 4 PM this afternoon to 9 AM EDT
     Sunday for VAZ054.
     Coastal Flood Advisory until 2 PM EDT this afternoon for
     VAZ057.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for ANZ530>534-
     537>543.
     Small Craft Advisory from 6 PM this evening to 6 AM EDT Sunday
     for ANZ536.

&&

$$

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