259
FXUS61 KLWX 191817
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
217 PM EDT Sun May 19 2024

.SYNOPSIS...
Slightly drier conditions are expected today along with a few breaks
of sunshine as low pressure pushes off the coastal Carolinas and
high pressure builds in from the east. Warming temperatures are
expected Monday and Tuesday as high pressure builds overhead. A
strong cold front approaches from the Midwest and Ohio River Valley
Wednesday before crossing the area Thursday. The front stalls to the
south Friday before lifting back into the region this weekend to bring
additional chances for showers and thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
Visible satellite shows some clearing of the low clouds,
primarily along the mountains and portions of the Shenandoah
Valley and Chesapeake Bay. Overall the cloud layer is thin
however, with some visible thinning and breaks elsewhere,
especially as we head into the afternoon.

Gradual improvement in conditions is expected through the day,
reaching high end MVFR/low end VFR in the next few hours. Guidance
continues to suggest isolated to widely scattered showers at
most this afternoon, focused along the mountains and east of the
Blue Ridge. Any showers should be brief and the vast majority of
the area should stay dry.

Temperatures today remain dependent on cloud clearing, but still
anticipate 70s for most of the area. Notably a N/S swatch of the
DC metro from western Montgomery county to southern Fauquier
county is a degree or two warmer than the surrounding area,
thanks to a boundary cutting through the cloud cover for a few
hours earlier this morning.

Low clouds and patchy fog may return tonight with damp soils
from recent rainfall and high pressure building in, with the
greatest reduction in visibility expected in the few hours
before and immediately after sunrise.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Monday begins our reprieve from unsettled conditions with dry
weather and sunny skies in the forecast as high pressure builds
in. High temperatures rise to the mid-upper 70s, starting a
warming trend through mid-week as well. Low clouds and fog from
Sunday night should burn off by late morning, hanging the
longest along the Chesapeake and Potomac. Clear skies and
lingering moisture likely yield patchy fog once again Monday
night into Tuesday morning. Low temperatures will be in the mid-
upper 50s.

Dry and sunny conditions continue through Tuesday, high pressure
remaining overhead but gradually sliding eastward. High
temperatures warm into the upper 70s to 80s. While not currently
forecasting fog Tuesday night, with dewpoints in the upper 50s
to low 60s, if we cool enough overnight some patchy fog could
develop, but it`s not looking as certain as Sunday and Monday
night.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Overall not much change in our current weather pattern over the last
few weeks. We still remain in the cycle of 1-2 days of sensible
weather followed by 2-3 days of unsettled conditions. Unfortunately,
as we head into the middle and latter half of the workweek the
unsettled weather looks to return.

Strong low pressure over the upper Great Lakes region and it`s
associated cold front draped across the Upper Midwest/Ohio River
Valley will gradually push east Wednesday as the upper level ridging
breaks down. 06z/12z guidance continues to slow the progress of the
front east Wednesday with most of the guidance favoring Thursday
into Thursday night. This is due in part to the placement of the
departing surface high off the NJ/Long Island coast and secondary
surface high pressure over the southern Appalachians region. Even
with that said, a few showers and thunderstorms (some of which could
be strong) remain possible in areas west of the Blue Ridge Wednesday
afternoon and evening as an initial piece of shortwave energy
pivoting around the upper level low passes through. Most locations
will remain dry with increased south to southwesterly winds boosting
temperatures into the mid to upper 80s to near 90 outside the
mountains/bay.

The cold front looks to push through the area Thursday into Thursday
night before stalling to the south Friday. Latest 12z guidance
suggest a frontal passage right during the peak heating period
Thursday mid to late afternoon. This will allow both CAPE and shear
to maximized lending to a potential severe weather threat. Right
now, the Storm Prediction Center makes a mention of this threat on
there Day 5 outlook. CSU Learning Machine Probabilities also
highlight areas along and east of the Blue Ridge (i.e I-95 corridor
in the 15-30 percent probabilities of severe thunderstorms) during
this timeframe. Multi-ensemble CAPE values range from 500-1000 J/kg
on Wednesday before rising into the 1000-1500 J/kg range by Thursday
afternoon. With the approach of the front, it remains to be seen if
the increasing vertical shear (35-45kt) can coincide with the higher
CAPE values. As a result, strong to severe thunderstorms remain
possible Thursday afternoon and evening. Some storms will be capable
of damaging winds and large hail given the antecedent conditions. As
for coverage, some uncertainty remains given any cloud cover early
on and the resultant timing of the front as it passes through. High
temperatures Thursday will once again be in the mid to upper 80s
with 70s over the mountains.

The front stalls south and east of the area Friday before retreating
back north into the start of the weekend. Additional shower and
thunderstorm chances are likely as a result although uncertainty
remains in the overall pattern. High pressure tries to briefly build
back into the area Sunday before another series of fronts impact the
area by the early part of next week.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Gradual improvement in conditions is expected through the day,
reaching high end MVFR/low end VFR in the next few hours. Guidance
continues to suggest isolated to widely scattered showers at
most this afternoon, focused along the mountains and east of the
Blue Ridge. Any showers should be brief and the vast majority of
the area should stay dry, but if they impact the terminals,
could see brief reductions back to MVFR.

Low clouds and patchy fog may return tonight with damp soils
from recent rainfall and high pressure building in, with the
greatest reduction in visibility expected in the few hours
before and immediately after sunrise. Conditions should improve
by late Monday morning. Afterwards, dry and sunny conditions are
expected through Tuesday with winds remaining fairly light out
of the S/SE.

A strong cold front will approach the region Wednesday before slowly
passing through Thursday into Friday. Some restrictions are possible
especially Thursday into Thursday night as the front crosses. This
is due in part to an increase in shower and thunderstorm activity
especially along and east of the Blue Ridge. The front stalls to the
south late Thursday into early Friday before retreating back to the
north to start the weekend. Additional restrictions are possible
during this time. South to southwest winds are expected Wednesday
into Thursday before shifting to the west and northwest Thursday
night into Friday.

&&

.MARINE...
No hazardous marine conditions are expected through Tuesday.
Winds remain fair, easterly the remainder of today, SE Monday
and S/SE on Tuesday. As winds turn more southerly, some
channeling is possible but is not currently expected given the
light flow.

Some SCA level southerly channeling is possible Wednesday into
Wednesday night ahead of an approaching cold front from the Ohio
River Valley. The cold front looks to slowly cross the waters
Thursday afternoon into Thursday evening bringing the risk of
showers and thunderstorms. Special Marine Warnings may be required
for the stronger storms. Winds shift to west-northwest behind the
front Friday as it stalls south of the waters.

&&

.TIDES/COASTAL FLOODING...
With low pressure pushing off the coastal Carolinas and high
pressure building in from the east, water levels should start
to decrease under north-northeast flow. More sensitive locations
such as Annapolis, Straits Pint, and DC Waterfront could see
minor tidal flooding over the next 2 high tide cycles. Anomalies
do creep up again late tonight into Monday. This is in response
to a light wind which may allow some of the elevated water
levels to snap back. Winds turn more easterly again on Monday
yielding further rises. Additional tidal flooding is possible as
this occurs.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Advisory until 7 PM EDT this evening for DCZ001.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...CAS
SHORT TERM...CAS
LONG TERM...CAS/EST
AVIATION...CAS/EST
MARINE...CAS/EST
TIDES/COASTAL FLOODING...EST