Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 260126 AAA

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
926 PM EDT Wed May 25 2022

A front will remain stalled to the south of the region as high
pressure remains over the Northeast U.S. The front to the south
will move northward as warm front on Thursday. An occluded
system will impact the region late this week into the early part
of the weekend. High pressure returns for the early parts of
next week.



Weak low pressure off of Cape Hatteras and high pressure over
the NW Atlantic will maintain an easterly upslope flow into the
Blue Ridge Mountains through Thursday with light rain or drizzle
possible on the eastern slopes of the Appalachians and Blue
Ridge Mountains. Areas of light rain or drizzle may also develop
along the western shore of the Chesapeake Bay toward dawn.
Otherwise, remaining cloudy with lowering ceilings through the


The stalled front to our south will begin creeping north as a
warm front on Thursday. Early morning low clouds and drizzle may
also slide north across southern Maryland and Tidal Potomac and
farther into parts of the metro areas Thursday morning. As the
day progresses, we should less and less of low clouds and
drizzle as daytime heating should mix this out. The warm front
will continue to march north during the day Thursday. Winds will
become more southerly and increase both at the surface and a few
thousand feet above the ground Thursday afternoon. With this
increase in southerly winds comes an increase in low level
moisture; thus, PWATs could rise quickly from 1.25 to near 2
inches from early Thursday morning through late Thursday
evening. This moisture and increase in wind could set the stage
for an increased threat for violent thunderstorms and possible
flooding Friday into Friday night.

The instability will increase through the day on Thursday with
the added sunshine and warmth. Temperatures on Thursday will
trend upwards with highs expected to reach the middle to upper
70s. A leeside trough of low pressure nearly in sync with a warm
front pushing north of our region could be the zone in which
showers and a rumble of thunder form Thursday night and mainly
across the western zones.

Showers and thunderstorms, some on the strong to severe side,
could develop over the western zones Friday mid-morning and
carrying eastward Friday afternoon with addition development
into Friday evening. Heavy rainfall could lead to localized
flooding, while the more intense thunderstorms Friday afternoon
and evening could produce damaging winds and large hail. High
temperatures will reach the upper 70s to lower 80s on Friday
with dewpoint temperatures climbing into the middle to upper


An upper low will continue to move further east for the start of the
weekend. Do think there remains a potential for showers and a few
thunderstorms on Saturday afternoon as the upper low continues to
meander further east. GFS/ECMWF ensemble low locations display the
center of the upper low mainly to the north of the Mason-Dixon line.
Regardless, the low will likely be close enough to the area to keep
continuous chances for showers and maybe a few thunderstorms during
the day. The better likelihood for storms will be on Friday with the
actual cold front passage.

By Sunday, the low should be further east and clearing
skies/sunshine will likely allow us to dry out for the end of the
weekend. High pressure will begin to influence the region and bring
dry conditions through at least the early start of the work week.
Highs will be on an upward trend through early next week once the
low starts to move further offshore. Areas outside of the mountains
may start to see low 90s by Tuesday as a warmer airmass takes over
with drier conditions expected.


MVFR conditions could develop due to low clouds and patchy or
areas of drizzle. A southerly flow is expected to form Thursday
afternoon as warm front lifts north of the region. The cloud
deck will thin out Thursday afternoon but low MVFR ceilings will
continue to be possible through Thursday evening. Showers will
overspread all terminals on Friday leading to continue MVFR/IFR
visibilities and ceilings. Thunderstorms will be possible Friday
afternoon and evening.

Sub-VFR conditions possible on Saturday as an upper level low brings
showers and a few afternoon thunderstorms across the area as it
tracks further east. Winds will start out of the NW for the long
term period before pivoting to more southerly as the low continues
to move further east. VFR conditions are expected on Sunday.


Small craft advisories will likely be needed Thursday night and
especially into Friday due to southerly channeling winds and an
increasing low jet on Friday.

Expected sub-SCA conditions for the weekend. MWS`s and SMW`s may be
possible Saturday afternoon with any thunderstorms that bring enough
wind down to the surface over the waters but confidence is low in
this occurring. High pressure builds in on Sunday with light
southerly winds taking over as the upper low moves further


An onshore flow will yield elevated water levels the next few
days. Minor flooding is forecast at several locations along the
western shores of the Chesapeake Bay and the tidal Potomac
River. Additional Minor flooding may be achieved at the above
sites through Friday, as well as Annapolis, with a number of
other sites near minor thresholds that will require close
monitoring of trends. Behind a frontal passage late Friday,
water levels should begin to trend downward, diminishing the
threat for flooding heading into the holiday weekend as winds
shift offshore.




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