Cloverly, Maryland Weather Forecast Discussion

977
FXUS61 KLWX 231414
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1014 AM EDT Tue Sep 23 2025
.SYNOPSIS...
High pressure will shift further offshore today allowing an area of
low pressure and cold front to approach the region. The front will
be slow to cross the area Wednesday through Friday. This will lead
to increased shower and thunderstorm chances each day as a series of
low pressure systems traverse the stalled boundary. High
pressure gradually returns from the west this weekend into
early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Visible satellite shows high level clouds moving northeast
across the area with cumulus clouds developing along the metros
and west of the Alleghenies. No changes were made to the
forecast with the 12Z HRRR and NAMnest continuing the trend of
showing convection initiating between 1-2PM west of the Blue
Ridge and reaching the metros between 4-7PM. Rain showers
continue to move along the Alleghenies this morning with
convection initiation this afternoon dependent on how far cloud
cover expands east. Previous forecast discussion included below.
Patchy river/high mountain valley fog look to continue through
daybreak this morning, especially in locations that did see rain
yesterday. Some onshore advection fog has been noted over the
western shore of the bay as well as southern MD and the northern
neck of VA given increasing moisture in light southerly return flow.
High pressure will push further offshore as an area of low pressure
over the central US and it`s associated cold front slide closer to
the region. A series of perturbations look to traverse this boundary
as it gradually sags south and east from the Great Lakes and
Missouri/Ohio River Valleys.
For today, the boundary looks to remain west of the region. A lee
trough looks to form along the Alleghenies/Appalachians this
afternoon acting as a catalyst for convective development. 500 mb
flow will continue to remain out of the west with south to southwest
flow at the surface. This will give a bit more movement and
organization of storms east of the mountains. 00z/06z modeled shear
values from hi-res CAMS/soundings look to be ballparked between 20-
30 kts. Instability (CAPE) values look to run between 1500-2000 j/kg
east of the Alleghenies given high temperatures in the mid to
upper 80s and dewpoint values climbing into the upper 60s. The
added moisture will push PWATS into 1.5 to 2 inch range yielding
efficient rain producing storms.
Current 00z CAMS continue to focus on a narrow window from 2 to
8pm for the highest window of convective development. Coverage
will be scattered with a mix of linear and multicell clusters
capable of producing damaging winds and heavy rainfall. Storms
look to initiate over the Alleghenies around midday before
working east toward the I-81 and US-15 around 3-5pm and off
toward the I-95 metros between 5-7pm. The Storm Prediction
Center continues a Marginal Risk (Level 1 out of 5) for severe
weather for areas east of I-81 this afternoon with wind
remaining the primary concern. The risk for severe weather
should quickly diminish after sunset with the loss of daytime
heating. Overnight lows fall back into the upper 50s to mid 60s
with areas of patchy fog late especially for those who did see
rainfall.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Longwave troughing and the resultant slow moving cold frontal
boundary will inch closer to the region Wednesday. Meanwhile,
several perturbations of low pressure will work along the
boundary extending from the Ohio River Valley back into the Mid-
South Wednesday afternoon and evening. Meanwhile, a lee trough
will form once again in the vicinity of the Alleghenies and Blue
Ridge. This will act as the spark for scattered to numerous
showers and thunderstorms Wednesday afternoon into Wednesday
evening. Temperatures will be slightly lower Wednesday given
added cloud cover as the trough/front approach from the west.
Expect highs in the upper 70s and low 80s with dewpoint values
around 70 degrees. PWATS will continue to remain abnormally high
for this time of year with the 75th-90th percentiles hovering
between 1.5-2.1 inches. With the added cloud cover the severe
threat appears lower, but not zero. Storms could pack a punch
with heavy rain as the primary threat and gusty winds as a
secondary concern. Either way looking at another day of
beneficial rains for portions of the area given the recent
drought concerns. Any convection should slowly wane during the
late evening and overnight hours with the loss of daytime
heating. Fog cannot be ruled out, but confidence is lower given
increasing cloud cover. Lows Wednesday night will warm into the
mid to upper 60s along and east of I-95 with low to mid 60s west
(upper 50s mountains).
By Thursday, surface low pressure tracks into the Great Lakes
dropping it`s associated cold front into the region. This will lead
to a continuation of scattered to numerous showers and thunderstorms
across the area yielding beneficial rainfall. PWATS will remain
high running between 1.6-2.2 inches making for efficient rain
producing storms. CAPE (less than 1500 j/kg) and shear (less
than 35 kts) will also remain subtle leading to some organized
clusters of storms during the afternoon and evening hours. The
severe weather threat looks to remain low, but not zero.
Flooding also is not a concern although one or two issues (i.e
poor drainage) could sprout up in areas that see repetitive
rounds of heavy rain over the last few days. Once again this
threat is low given the recent drought concerns. High
temperatures Thursday will push into the upper 70s and low 80s
east of the mountains with overnight lows in the mid to upper
60s east of US-15 (upper 50s and low 60s west).
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A weak cold front is forecast to push through the northwestern half
of the area Thursday night, but may stall to the southeast with
precipitation chances and increased cloud cover lingering across
eastern areas Friday into the weekend. Trough axis east of the MS
River Valley Thursday is forecast to split and form a cutoff
low across the Southeast with a narrow ridge axis forming over
the area early next week. A tropical system may approach the
Southeast coast early next week with any possible impacts
holding off until later next week or at the start of October.
Expect highs in the mid 70 to low 80s outside the mountains.
Overnight lows will remain in the low to mid 60s for most with 50s
west of the Blue Ridge.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
Prevailing VFR conditions are expected amongst the terminals through
this afternoon. Some brief reductions have been noted with a fading
cluster of showers and thunderstorms mainly west of KMRB. This
activity should continue to fall apart as it works into the corridor
this morning. Overall looking at SKC to SCT-BKN mid and high level
clouds later this morning into the early afternoon hours. Clouds
will gradually increase from the west given convective development
along a lee side trough draped between the Alleghenies/Appalachians
and Blue Ridge. The trough will spur convective development from
west to east across the local airspace this afternoon. Have
continued the usage of PROB30s at all TAF sites this afternoon and
evening for thunderstorm development. Will re-evaluate for TEMPOS
during the 12z/8am TAF cycle. Greatest convective coverage looks to
occur between 18-00z/2-8pm. Scattered thunderstorms should
initialize west of KMRB between 16-19z/12-3pm before pushing east
toward the corridor between 4-8pm. Gusty winds and heavy rain look
to be the biggest threat with storms leading to brief vsby
reductions of 3-5 SM. All convection looks to wane beyond 01z/9pm
with the loss of daytime heating. Some residual showers are possible
through midnight with partly to mostly cloudy skies overnight.
Additional rounds of showers and thunderstorms are possible
Wednesday leading to a continuation of temporary sub-VFR reductions.
Coverage looks to be scattered to numerous given the proximity of
the incoming front and lee side trough nearby. Timing remains a bit
more uncertain in regards to the storms with an emphasis on the
afternoon and evening hours. Similar sub-VFR reductions are likely
Thursday and Friday as the front stalls overhead and several waves
of low pressure pass along it. This will lead to a continuation of
scattered to numerous showers and thunderstorms across the region.
Winds today will remain out of the south at 5 to 15 kts with gusts
up to 20 kts at times during the afternoon and evening hours. More
chaotic winds will be noted in and around thunderstorms. South to
southwesterly winds are expected Wednesday into Thursday before
shifting to the northwest Friday. Speeds will sit between 5 to
15 kts during the afternoon and evening hours.
&&
.MARINE...
Winds will drop back below SCA levels this morning with an
additional period of southerly channeling possible later this
evening and into the overnight hours.
Outside of southerly channeling, convective chances due make a
return to the waters today and Wednesday. This is in association
with a slow moving front and several pieces of low pressure that
look to cross the waters through late week. Expect the risk for
gusty showers and thunderstorms each afternoon through Friday.
Special Marine Warnings may accompany any of these stronger
thunderstorms. Winds will remain out of the south Tuesday
through Wednesday afternoon below SCA levels.
SCAs may be needed late Thursday into Friday as the front crosses.
This will lead to a wind shift from the southwest to the
northwest Friday. Shower and thunderstorm chances look to
continue over the waters on both days with coverage lowering
into the upcoming weekend ahead.
&&
.TIDES/COASTAL FLOODING...
Anomalies are forecast to remain slightly elevated through Thursday,
so additional near minor flooding is possible at sensitive
locations. This is most likely with the higher daily tide cycle in
the afternoon and evening, with the strongest onshore flow and
highest anomalies possible on Thursday into Friday.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...EST
NEAR TERM...AVS/EST
SHORT TERM...EST
LONG TERM...LFR
AVIATION...LFR/EST
MARINE...LFR/EST
TIDES/COASTAL FLOODING...LWX

NWS LWX Office Area Forecast Discussion