Ashburn, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

270
FXUS61 KLWX 021430 AAA
AFDLWX

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
1030 AM EDT Wed Apr 2 2025

.SYNOPSIS...
High pressure will build to the north near New England through
today as deep low pressure develops over the Plains and moves
into Canada. A warm front ahead of the low will lift through the
area tonight. The cold front will move into the area Thursday,
then meander nearby through Saturday before another area of low
pressure lifts by Sunday. High pressure will likely return for
early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

High level clouds will thin out some this afternoon, but at the
same time, low-level clouds will advect northward this
afternoon keeping mostly cloudy/cloudy skies all day. Showers
should hold off until this evening.

Previous afd...

Early this morning, a deep upper low was moving into the north-
central Plains while strengthening on the leading edge of broad
troughing over the western CONUS. Another upper low was near the
Canadian Maritimes. In between, weak ridging was positioned over
the eastern CONUS.

Mid and high clouds streaming eastward ahead of the west CONUS
trough/Plains upper low will result in a mostly cloudy day
especially west of I-95. Strong high pressure moving over
northern New England will send a wedge of cool air across the
area today likely keeping highs in the 50s to lower 60s. Have
blended MOS guidance with NBM to lower temps several degrees.

Remnant showers leftover from convection developing over the OH
Valley this morning could move across northern MD this afternoon
as a few additional warm advection showers pop up west of US-15.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Precipitation chances will gradually increase tonight, with the
most likely area to see rain along and west of the Appalachians.
A warm front is expected to lift northward ahead of the Plains
low tonight, though it is unclear just how quickly it moves
north. A few showers are possible as the front passes.

As the main area of low pressure lifts into Canada, a cold front
will sag southeastward into the region Thursday. After a cloudy
start, heating especially south of the US-50 corridor should
result in building instability when paired with rising Tds.
Multiple subtle waves aloft will ride along the approaching
front, and may trigger a few thunderstorms late Thursday into
Thursday night. The main question is convective coverage given
somewhat amorphous and uncertain forcing (which will be tied at
least in part to prior day`s convection), as well as potential
for downsloping flow and a stout cap evident in forecast
soundings around 2,000-4,0000 feet. If thunderstorms were to
develop, ample deep layer flow exists for a damaging wind risk.

The front is expected to stall near or over the area Friday
which results in continued chances for showers and a few
thunderstorms, though with decreasing certainty.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
A frontal boundary stalled to the south will lift north through
the forecast area as a warm front with a slight chance to
chance of precipitation throughout the day. On Sunday, a cold
front pushes through the forecast area, leading to widespread
precipitation chances. Conditions dry out Monday and into
Tuesday as the frontal boundary exits offshore.

There is a good bit of model disagreement when it comes to the
temperature forecast for the weekend with temperatures varying
greatly depending on the placement of the frontal boundary. For
right now, have high temperatures ranging from 60s in NE MD to mid
80s in the southernmost portions of the forecast area for Saturday
and Sunday. In the wake of the cold front, high temperatures
will gradually decrease Monday and Tuesday. Highs on Monday will
be in the 50s and 60s with highs on Tuesday in the 40s to 50s.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
VFR mid/high clouds are expected through this evening, with
lower clouds developing in onshore flow tonight. Guidance is in
good agreement with low-end MVFR to IFR developing later tonight
generally after 06Z. SE flow today will become S tonight with
gusts of 20-25 kts at times especially this afternoon. A pop up
shower or two can`t be ruled out, but confidence in impactful
precip was too low to mention with the 06Z TAF package.

Low ceilings should gradually clear and lift through midday
Thursday, with VFR returning Thursday afternoon. A few
thunderstorms may developing along and ahead of a sagging cold
front late Thursday into Thursday night, with uncertain chances
lingering into Friday. Winds will be generally SW to W during
this time with gusts of 20-25 kts possible, though direction
will become N in the wake of the front near northern terminals.

SUB-VFR conditions are possible Saturday and Sunday as multiple
frontal boundaries bring widespread precipitation to the forecast
area. Southerly winds on Saturday shift to southwesterly on
Sunday.

&&

.MARINE...
Southeast winds today will become south tonight then southwest
Thursday. Frequent gusts of 15-25 knots with a few gusts of 30
knots are anticipated. A cold front will approach Thursday then
stall Friday, with a few showers and thunderstorms possible at
times especially late Thursday into Thursday night.

Prevailing winds are expected to become lighter Friday with the
front overhead, with north winds behind the front over northern
waters, but continued west to southwest flow to the south.

Southerly winds near but are expected to stay below SCA criteria on
Saturday. Winds shift to southwesterly on Sunday, with SCA
conditions likely.

&&

.TIDES/COASTAL FLOODING...
As high pressure shifts offshore on Thursday, tidal anamolies are
expected to rise due to southerly winds. Sensitive tidal locations
such as Baltimore, Annapolis, and Havre De Grace will reach action
stage and near minor flood stage Thursday morning.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 PM EDT Thursday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT Thursday for ANZ530>543.

&&

$$

SYNOPSIS...DHOF
NEAR TERM...LFR
SHORT TERM...DHOF
LONG TERM...AVS
AVIATION...AVS/LFR
MARINE...AVS/LFR
TIDES/COASTAL FLOODING...DHOF