723
FXUS61 KLWX 190738
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
338 AM EDT Thu Jun 19 2025

.SYNOPSIS...
Heat and humidity continue today ahead of a potent cold front that
looks to cross the region. The front will bring a widespread risk of
severe weather to the area later this afternoon and evening with
damaging winds, large hail, and heavy rainfall as the primary
concerns. Drier and less humid Friday into Saturday as high pressure
builds into the region. A prolonged period of excessive heat is
expected Sunday into the middle part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Shaping up to be an active afternoon and evening ahead as a potent
cold front and upper level trough swing across the region. The Storm
Prediction Center has upgraded areas east of US-15 to an Enhanced
Risk (Level 3 out of 5) for severe weather today. Locations further
west remain in a Slight Risk (Level 2 out 5). Regardless of the
severe risk zones, all hazards will be on the table with t-storms
today.

SEVERE THREAT: Storms look to initiate over the mountains
between 16- 19z/12-3pm ahead of the incoming front. Areas
further east will likely see storms develop between 2-4pm/18-20z
with a prefrontal shortwave trough pushing through. Convection
overall will be scattered mainly along and west of I-81 with
conglomeration of supercells and organized line
segments/clusters working east toward the Baltimore/DC metro
areas between 19-23z/3-7pm. Storms will fuel off of high
temperatures in the upper 80s and low to mid 90s with dewpoint
factors in the upper 60s and low 70s. Heat indices will climb
toward 100 degrees in the metros/east of the Blue Ridge as A
result of the increased humidity.

SBCAPE values look to surge into the 1500-2500 j/kg during the peak
heating period with steep low level lapse rates (7+ C/KM). 0-6 km
bulk effective shear values will run between 40-60 kts with 0-1 km
SRH values around 100-200 m2/s2. This will amplify the damaging wind
threat as well as the potential for an isolated tornado or two
across the region. Updraft helicity tracks illustrate the potential
tornado threat especially east of I-95 and down across southern
MD/the northern neck of VA where slight better spin resides
(with a potential bay breeze/outflow interaction).

FLASH FLOOD THREAT: Outside of the severe threat, instances of flash
flooding will remain an issue mainly in the metros/over the terrain.
This is largely due in part to some hypersensitivity given the
recent rainfall yesterday and really over the last week. FFG
guidance for much of the area in the 1, 3, and 6 hr time windows
remains less than 1" with PWATS ahead of the front approaching
2". Rain rates of 1-2"+/hr are possible with storms as they pass
through. The good news is that storms will be progressive given
the amplified shear across the region.

Shower and thunderstorm activity will quickly race eastward
this evening between 00-03z/8-11pm. Winds will remain elevated
out of the west and northwest with gusts running between 15 to
25 mph. Winds will decrease late tonight along with humidity
under west to northwest flow. Some fog may be possible in the
river valleys although wind may be a limiting factor. Lows
tonight will fall back into the upper 50s and low 60s north and
west of the urban centers. Low to mid 60s are expected for the
Baltimore/DC city centers and locations near the bay.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The humidity finally lowers along with a brief reprieve in the
excessive heat as we round out the workweek. Strong upper level
ridging and surface high pressure will build over the eastern CONUS
through the start of the weekend. The surface high and upper level
ridge will continue to strengthen each day bringing warming
temperatures and eventually more humidity. For Friday, expect highs
back in the mid 80s with dewpoints in the 50s and low 60s. Overnight
lows Friday night will fall into the upper 50s and low 60s west of
the Blue Ridge with mid to upper 60s in the metro areas. A spotty
shower or t-storm cannot be ruled out in northwest flow late Friday
afternoon and evening as a weak piece of trailing shortwave energy
slides north and east of the area. Highest confidence for this to
occur would be along the PA/MD line and west of the Catoctins. For
now, hedged PoP chances at less than 15 percent given ample dry air
advection settling in with building surface high.

Low humidity continues Saturday although temperatures push back into
the upper 80s and low 90s under light southerly flow. Lows Saturday
night will drop back into the mid to upper 60s and low 70s. Humidity
will gradually increase during this time as broad 1024-1028 mb high
pressure strengthen of the Carolina coast.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The longwave pattern across the CONUS will remain relatively
stagnant through the long term period, with deep upper troughing
centered over the Western US, and a strong upper ridge present
across the Eastern US. The center of a corresponding mid-upper level
anticyclone will remain centered overhead throughout the period. 500
hPa heights are modeled to reach around 596-598 dam during this
period. As a result, an extended stretch of heat and humidity is
expected late this weekend through the middle of next week.

Model guidance is in good agreement that 850 hPa temps will soar to
above 20C, which will lead to daytime highs well into the 90s, and
potentially even nearing 100. Dewpoints will remain in the low 70s,
which will keep overnight lows in the 70s. Heat indices will climb
to in excess of 100 each day, and could even reach 105-110 some
days. While dewpoints will be high at the surface, sinking motion
near the center of the mid-upper level anticyclone will lead to dry
conditions in the mid-upper levels, and quiet weather at the
surface, with ample sunshine during the daylight hours. Those who
are sensitive to the heat are encouraged to take preparations in
advance for what will likely be an extended heatwave locally.


&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
VFR conditions continue to prevail amongst the terminals this
morning with a few high level clouds. Some patchy pockets of MVFR
fog are mixed in especially at terminals that sit close to waterways
or in areas that did receive recent rainfall. Any fog will quickly
dissipate after 13z/9am given the high sun angle.

Expect temporary drops to sub-VFR this afternoon and evening as a
potent cold front cross the region. The front will bring numerous
showers and thunderstorms to the terminals especially within the BWI-
IAD-DCA corridor. Storms fire prior to 20z/4pm west of KMRB and
KCHO before working east toward the corridor between
19z-23z/3-7pm. Went ahead and added TEMPOs in for this time
window at the aforementioned terminals above. Expect variable
wind gusts in and around thunderstorms with gusts in excess of
30-40 kts. Convection will clear the corridor between
00-03z/8-11pm tonight with improvements back to VFR. Light
southwest winds this morning will increase this afternoon and
evening with gusts between 20-25 kts.

VFR conditions are expected Friday as high pressure builds back into
the region. Winds will remain out of the west and northwest at 5-10
kts. Winds switch to the south Saturday as high pressure sinks south
and east of the area.

VFR conditions and light winds are expected on both Sunday and
Monday.

&&

.MARINE...
A strong cold frontal boundary will cross the waters today bringing
numerous showers and thunderstorms. SMWs are possible given
thermodynamic and kinematic environment this afternoon and evening
in any thunderstorm. SCA conditions are also expected this afternoon
and into Friday with the cold frontal passage. Southwest winds today
will switch to the northwest this afternoon and evening with gusts
up to 25 kts.

Sub-SCA level winds return Friday afternoon with west to northwest
winds are expected. Winds will become southerly Saturday afternoon
at generally 10 knots or less.

Light and variable winds are expected over the waters on both Sunday
and Monday. No marine hazards outside of heat are expected for the
middle of next week.


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory from 1 PM this afternoon to 6 AM EDT
     Friday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 1 PM this afternoon to 6 AM EDT
     Friday for ANZ530>534-537>541-543.
     Small Craft Advisory from 1 PM this afternoon to 9 PM EDT this
     evening for ANZ535-536-542.

&&

$$

SYNOPSIS...KRR
NEAR TERM...EST
SHORT TERM...EST
LONG TERM...KJP
AVIATION...KJP/EST
MARINE...KJP/EST