Area Forecast Discussion Issued by NWS Sterling, VA
000
FXUS61 KLWX 100753
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
353 AM EDT Wed Apr 10 2024
.SYNOPSIS...
High pressure will remain offshore through the middle of the
week while a frontal system approaches from the west. Potent low
pressure and its associated cold front will cross the area
Thursday night. High pressure will return Friday into Saturday,
then another frontal system may approach Sunday into Monday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of this morning, a weak piece of shortwave energy is sliding
across the region, resulting in some scattered showers moving
from south to north over the area. Coverage is less than
originally anticipated, so have decreased POPs area-wide from
the overnight forecast.
Showers and a few thunderstorms are possible today, primarily
west of the Blue Ridge, as a piece of shortwave energy lifts
north through the region.
Have decreased POPs tonight as that drying trend mentioned last
night has continued. Can`t completely rule out some isolated
showers, but should be mostly dry.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Rain chances begin to increase by Thursday morning as the
frontal system inches closer to the region, but the bulk of
precipitation likely arrives Thursday afternoon. Strong
southerly winds are expected to develop ahead of the approaching
cold front, which could reach 25 to 35 mph or so. Brought them
down a bit from the previous forecast due to uncertainty
regarding stability.
The upper trough that had been digging into the MS River Valley
will lift northeastward towards the Great Lakes, becoming
negatively tilted into Thursday evening/night. Given the amount
of pre-frontal showers and clouds, instability looks to be hard
to come by, especially with the timing looking to be later in
the evening into Thursday night. Not seeing many members in
ensembles with greater than around 300-400 J/kg of CAPE, which
is going to be hard to overcome. That being said, there is a
good amount of shear available (50-70 knots depending on
location). If anything does manage to become organized and
surface based, damaging wind gusts are possible. This would
likely be with the main line of convection just ahead of the
fropa Thursday night.
Along with all of this, given the very warm and moist air mass
in place, these storms will be capable of very heavy rainfall
as well. Ensemble guidance suggests that PWAT values could be in
the 1.75-2+ inch range. While the period of heaviest rainfall
should move through rather quickly, there could still be an
isolated flooding threat, particularly in areas of poor
drainage.
For Friday, the primary trough will swing through the region.
This will bring with it the chance for showers and thunderstorms.
Additionally, cooler temperatures and gusty southwest winds can
be expected on Friday. Winds will most likely be around 20 to
30 mph with gusts up to 45 mph possible. Highest winds will be
for those in the western portions of the forecast area, especially
at higher elevations. High temperatures will be a few degrees
cooler than previous days with temperatures in the 60s for most
with those west of the Blue Ridge in the upper 40s to upper 50s.
Conditions begin to dry out more by the late evening to early
overnight hours Friday night with lows in the upper 30s for the
mountains and 40s to 50 further east.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Surface high pressure to the south will provide the area with dry
and windy conditions for Saturday. west/northwest winds blowing 10-
20 knots and gusting 20-30 knots are expected areawide. The only
exception is for those along and west of the Alleghenies where
higher elevations lead to sustained winds of 20-25 knots and gusts
30-40 knots. Sunny skies are expected, especially in the afternoon
as moisture aloft moves away from the forecast area. High
temperatures will be in the 60s(50s in the mountains) with
overnight lows in the 40s to low 50s.
On Sunday, a surface low will be over the Great Lakes while the
associated warm front brings low end PoPs(less than 30%) to the
northern half of the forecast area. In the wake of the warm front,
temperatures will be noticeably warmer with highs in the upper 70s-
low 80s for those at lower elevations. Mountainous areas will see
high temperatures in the upper 60s to low 70s. Overnight low
temperatures will be in 50s to low 60s.
As the area of low pressure travels into New England, the associated
cold front will most through the area on Monday and stall to our
south on Tuesday. This will bring a slight chance to a chance of
precipitation to the area each day, with peak timing coinciding
with peak day time heating. Temperatures will be warm each day with
highs in the 70s-80s for most. Those at higher elevations will stay
in the upper 60s. Overnight temperatures cool to the 50s each
night.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Brief VSBY reductions possible in light shower this morning, but
likely very minimal in terms of impacts. Winds today remain
light out of the S/SSW AOB 10 knots for the most part. Winds
will begin to increase overnight into Thursday morning however.
Sub-VFR conditions are expected Thursday through Thursday night
with IFR conditions possible. A strong low-level jet may also
lead to low-level wind shear, depending on how much stability
there is during the time of the strongest low-level winds.
Sub-VFR conditions are possible Friday as showers and a possible
thunderstorm impact all terminals. In addition to precipitation,
gusty west/southwest winds are expected throughout the day with
winds blowing upwards of 30 knots at all terminals. CHO and MRB
should have the strongest gusts, which could approach 40 knots.
VFR conditions are expected at all terminals on Saturday as high
pressure impacts the area. Westerly wind gusts of 25-30 knots are
expected in the afternoon before winds shift to southwesterly and
gust 15-20 knots on Sunday. Sub-VFR conditions are possible at all
terminals, except for CHO, on Sunday as precipitation moves to our
north.
&&
.MARINE...
Light S to SSW flow is expected today, increasing late on Wednesday
night through Thursday night. SCAs are likely by Thursday morning.
Despite very strong low-level flow just above the surface, air
temperatures much warmer than the water temperatures will create
near surface stability and reduce efficient mixing, likely
keeping gusts in the SCA range outside of showers and thunderstorms
through Thursday.
High-end small craft caliber winds are most likely Friday and
Saturday with an elevated pressure gradient over the waters.
Gale-force winds are possible at times, especially across the
northern waters of the Chesapeake Bay on either day. An SMW may
be issued Friday as a result of thunderstorms crossing the
waters.
Small Craft Advisory winds are expected both Saturday and Sunday.
Westerly winds gust 20-30 knots over the waters on Saturday before
shifting to southerly on Sunday and gust 15-20 knots.
&&
.TIDES/COASTAL FLOODING...
As southerly flow intensifies Wednesday night through Friday,
tidal anomalies are expected to significantly increase. For the
higher high tide cycles today into tonight, minor flooding is
possible in Annapolis, DC, and Straits Point. By Thursday
though, at least minor tidal flooding is expected for most
locations, and perhaps even getting to moderate, especially in
those sensitive areas.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 10 AM EDT this morning for MDZ014.
Coastal Flood Advisory until 6 AM EDT early this morning for
MDZ017.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...DHOF
NEAR TERM...CJL
SHORT TERM...CJL/ADM
LONG TERM...AVS
AVIATION...AVS/CJL
MARINE...AVS/CJL
TIDES/COASTAL FLOODING...CJL