Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 221818

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
218 PM EDT Sun May 22 2022

A cold front will pass through the area tonight. The front will
stall over the Carolinas Monday and Tuesday before returning
north as a warm front Wednesday through Thursday as low pressure
passes by to the west. The cold front associated with that low
may cross the area by Friday.


A southerly flow ahead of a cold front has led to hot and humid
conditions this afternoon. Max temps will be in the upper 80s to
lower 90s for most locations (70s and lower 80s in the mountains
and near the Bay).

The heat and humidity will lead to moderate amounts of CAPE. The
latest mesoanalysis shows around 1-2KJ/KG of SBCAPE west of the
Blue Ridge and 2-3KJ/KG of SBCAPE east of the Blue Ridge.

Stronger lifting mechanisms will continue to lead to the
likelihood for showers and thunderstorms. A surface trough will
act as a lifting mechanism along with an MCV moving in from the
west and a strong cold front that will be moving into the area
tonight. A couple rounds of showers/thunderstorms are possible,
first with the pressure trough, and then with the MCV and cold
front. Shear profiles are marginal (deep layer shear around
20-30 kts) and mid-level lapse rates are marginal as well.
However, the heat and humidity has led to moderate CAPE ahead
of the cold front. The moderate CAPE combined with steep low-
level lapse rates and mid-level dry air will increase threat
for damaging wind gusts. Latest mesoanalysis shows over 1000
j/kg of DCAPE for much of the area. A Severe Thunderstorm Watch
is in effect for areas east of the Allegheny Highlands through 9

Storm motion should be fast enough to keep any flood threat
localized, but non-zero due to the fact that there may be a
couple rounds of heavier rain associated with thunderstorms.
Storms should exit southern MD around midnight, and the cold
front will drop to our south overnight. Much cooler conditions
are expected behind the boundary. lows will fall into the 50s to
lower 60s.


The cold front will stall out over the Carolinas for Monday
through Tuesday night while high pressure remains to the north.
An upper-level trough will develop over the Rockies and central
CONUS during this time.

An upper-level disturbance will pass nearby to our south in the
southern stream Monday through Monday night, and this combined
with the upper-level trough out west will cause warm and moist
air to overrun cooler air in place. This will bring plenty of
clouds along with the likelihood for rain across portions of
the area. The main uncertainty is how far north and east the
rain makes it before it runs into drier air and subsidence
associated with the high to the north. As of now, it looks like
the best chance for rain Monday will be south and west of the
Potomac River.

Plenty of clouds and cool weather will hang around for Monday
night through Tuesday night due to an onshore flow around high
pressure to our north. Some rain is possible, especially across
central and southern areas closer to upper-level disturbances
and shortwaves just to the south. However, there is still some
divergence among guidance so confidence is low at this time.


A warm front will continue moving north through the region on
Wednesday. Uncertainty exists regarding how far north the warm front
will make it due to a strong area of high pressure displaced to the
north. This will result in a return flow developing out of the south
resulting in a moisture and temperature return. Ahead of the warm
front, an on-shore flow will likely lead to mostly cloudy skies and
cooler conditions.

Thursday the region likely remains in the warm sector with the
associated cold front to the west of the region across the Ohio
valley. A strong southerly flow is likely to form which will lead to
strong warm air advection. WAA will lead to daytime temperatures
peaking in the low to mid 80s and will likely lead to an
increasingly unstable air mass with CAPE values potentially over
1500 J/kg. PW values may reach above 1.6 inches Thursday afternoon
into early Friday which could prime the environment for isolated
heavy downpours. Showers are likely on Thursday with a chance for
pulse thunderstorms from the relative unstable airmass. The greater
threat for strong to severe thunderstorms will likely occur late
Thursday into Friday. The forcing is better to the north, but the
negative tilt of the trough could result in added dynamics in an
unstable environment increasing the potential for showers and
thunderstorms. The timing of the frontal passage may hamper the
initiation of convection Thursday evening, though details will be
refined with the frontal passage timing. Showers along with a chance
for strong thunderstorms will be possible through early Friday
afternoon as the front progress through our region.

Behind the frontal passage, high pressure is forecast to build into
our region through the weekend leading to a return of dry and
somewhat cooler conditions.


Strong to severe storms are possible this afternoon, especially
through 00z. Damaging winds are the primary threat, but large
hail and heavy rain are possible as well. SubVFR conditions are
expected in any storms, with brief IFR/subIFR conditions

A cold front will push through this evening and shift winds to
the northwest and eventually north. There may be some rain and
low clouds near CHO on Monday through Tuesday, but the greater
risk of sub-VFR ceilings areawide will likely arrive Tuesday

CIGs and VSBYs are likely to cause restrictions on Wednesday prior
to the warm frontal passage due to persistent onshore easterly flow.
CIGs will increase after the frontal passage. Winds turn more
southerly behind the front into Thursday with shower and
thunderstorm chances returning Thursday afternoon into Friday


Strong to severe storms may impact the waters, especially around
20z through 02z. Damaging winds and large hail are possible.
Special Marine Warnings will likely be warranted.

A cold front will pass through the waters tonight. An SCA is in
effect for northwest winds behind the front that will turn north
toward Monday morning. Winds should decrease some later Monday,
but an onshore flow may strengthen again Tuesday and Tuesday
night with SCA conditions possible.

SubSCA conditions are likely for Wednesday but a southerly
channeling flow forming on Thursday may require Small Craft


Elevated anomalies will cause water levels to be around action
stage through high tide tonight. Anomalies should decrease
Monday with a northerly wind.


Please see record event reports (RERs) for records reached on
Saturday. Below is a list of temperature records today.

         Record Daily Warm Low Temperatures for May 22nd
Washington DC area........71 F (set in 1959)..................
Baltimore MD area.........71 F (set in 1903)..................
Sterling/Dulles VA area...67 F (set in 1975)..................
Martinsburg WV area.......68 F (set in 1959)..................

           Record Daily High Temperatures for May 22nd
Washington DC area........96 F (set in 1941)..................
Baltimore MD area.........98 F (set in 1941)..................
Sterling/Dulles VA area...89 F (set in 2021)..................
Martinsburg WV area.......98 F (set in 1934)..................

Temperature records for the Washington DC area have been
recorded at what is now Ronald Reagan Washington National
Airport (KDCA) since 1941. The official weather record consists
of that data back to 1945, and observations taken in downtown
Washington from 1872 through 1944.

Temperature records for the Baltimore MD area have been
recorded at what is now Baltimore-Washington International
Thurgood Marshall Airport (KBWI) since 1950. The official
weather record consists of that data, and observations taken in
downtown Baltimore from 1872 through 1949.

Temperature records for the Sterling/Dulles VA area have been
recorded at what is now Washington Dulles International Airport
(KIAD) since 1960. The official weather record consists solely of
that data.

Temperature records for the Martinsburg WV area have been
recorded at what is now Eastern West Virginia Regional Airport
(KMRB) since 1938. The official weather record consists of that
data back to 1944, and observations taken in downtown
Martinsburg from 1891 through 1943.

All climate data is considered preliminary until reviewed and
certified by the National Centers for Environmental Information


MARINE...Small Craft Advisory from 8 PM this evening to 2 PM EDT Monday
     for ANZ531>534-537-539>543.
     Small Craft Advisory from 8 PM this evening to 10 AM EDT
     Monday for ANZ530-535-536-538.
     Small Craft Advisory until noon EDT today for ANZ534-537-543.


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