Ashburn, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

734
FXUS61 KLWX 091431 AAA
AFDLWX

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
1031 AM EDT Sat May 9 2026

.WHAT HAS CHANGED...
Thunderstorm potential may be trending downward today and
upward for Sunday.

&&

.KEY MESSAGES...
- 1) Turning warmer this weekend with multiple opportunities
  for showers and thunderstorms.

- 2) Frost/freeze expected Monday night west of the Blue Ridge,
  followed by moderating temperatures and returning rain chances.

&&

.DISCUSSION...
KEY MESSAGE 1...Turning warmer this weekend with multiple
opportunities for showers and thunderstorms.

There will be a lot of mid and high level clouds throughout the
day as the shortwave trough approaches. As such, most models
have decreased instability forecasts (and surface dew points in
the upper 40s and 50s won`t help). The shortwave will still be
responsible for shower development along with possible
thunderstorms this afternoon as it crosses the area (highest
chances for the northern half). However, the meager instability
will likely limit the severe weather threat. Gusty winds will be
the main threat with any stronger thunderstorm, and perhaps
some small hail. SPC has maintained the Marginal/Level 1 Risk in
case a trend toward greater afternoon heating emerges. Any
convection will quickly depart to the east during the early
evening. Afternoon highs are progged to be in the upper 60s to
mid 70s, but values could be lower should thicker low level
clouds develop. Light winds tonight could lead to some fog
development.

Much of tonight and Sunday morning should be dry. After that, a
cold front will slowly settle in from the northwest, eventually
pushing to the south on Monday morning. Temperatures on Sunday
will rise into the 70s and lower 80s with more sun than today,
and surface moisture will continue to return northward.
Instability forecasts have trended upward in some guidance, with
multiple solutions now showing scattered thunderstorms
developing Sunday afternoon, particularly across the northern
half of the area. Similar to today, instability will be the
limiting factor, as bulk shear will again be over 40 kt.
Will have to monitor these trends for potential of gusty
thunderstorms.

Showers will fill in along the frontal zone Sunday night. A
wave of low pressure will form along the boundary as stronger
troughing digs southeast from the Great Lakes later Sunday night
into Monday. This could ultimately bring a steadier rain to
parts of the region, but these details remain uncertain. After
Sunday evening, thunderstorms will be unlikely as we end up on
the cool side of the boundary. Temperatures Monday will be in
the lower to mid 60s, if not upper 50s. Any lingering rain will
exit the area Monday afternoon. Unfortunately this system won`t
offer much drought relief, as probabilities for greater than a
half inch of rain are generally 30 percent or less.


KEY MESSAGE 2...Frost/freeze expected Monday night west of the
Blue Ridge, followed by moderating temperatures and returning
rain chances.

High pressure will quickly build in from the west Monday night. This
will result in light winds and favorable radiational cooling
conditions. Frost or near freezing temps could result in the
sheltered valleys near and west of I-81. This could be rather
impactful given the fact that we are approaching mid-May at this
point which is a couple weeks to a month past the median last freeze
for these areas.

The high pressure will drift offshore Tuesday marking return flow
and moderating temperatures. The warming trend will be more
noticeable heading into Wednesday as a warm front lifts into the
region, followed by a cold front and wave of low pressure Wednesday
night into Thursday. This frontal system will bring a chance of
showers and a few thunderstorms mid week.

Temperatures will actually trend warmer in the wake of the frontal
system at the end of next week as large scale height rises
commence.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
There is a higher likelihood of isolated to scattered
showers/thunderstorms this afternoon and evening between
18-23z/2- 7pm as an upper level disturbance crosses the area.
While some thunderstorms may produce gusty winds, instability
forecasts have been trending downward, which would result in
more benign showers. Have thus left the mention as PROB30. A few
southerly winds gusts to 20 kt could also occur throughout the
day.

Uncertainty increases tonight as winds become light and variable
in the wake of the showers. The typically moist models (e.g.
NAM) indicate fog and/or low clouds developing in this
environment, especially east of the Blue Ridge. However, am not
confident given the background south or west wind direction, so
am only adding a SCT MVFR cloud group for now due to the
uncertainty.

VFR conditions can be expected after sunrise Sunday. However, a
cold front will drop into the area during the afternoon.
Scattered thunderstorms could develop ahead of the boundary.
More widespread rain showers can be expected as this front
traverses the region, especially Sunday night into Monday
morning. Expect MVFR or IFR ceilings and visibilities during
this time. Northwesterly wind gusts may reach 20 to 25 knots in
the wake of the front Monday as ceilings lift.

VFR Tue-Wed with N winds gusting 15-20 kts Tue AM becoming light S
Tue PM. Gusts of 15-20 kts out of the S are possible Wed as a
frontal system approaches, with at least brief sub-VFR possible in
showers or a few thunderstorms.

&&

.MARINE...
A Small Craft Advisory remains in effect for all waters through
6 PM this evening due to enhanced southerly flow. However, the
forecast has trended toward more clouds and less mixing today,
so there could be some breaks in the gusts, especially over the
northern bay and upper Potomac. Isolated to scattered t-storms
may affect the waters this afternoon and early evening, which
may prompt SMWs due to gusty outflow winds. However, this threat
may be trending downward somewhat based on the latest data.

While it`s possible some gusts linger over southern Maryland
during the early evening, overall lighter winds are expected
tonight into Sunday. The chance for a few gusty thunderstorms
may be trending up Sunday afternoon and evening, especially for
the northern bay and upper Potomac. More widespread showers
along a cold front will likely cross the waters Sunday night
into Monday morning. This front will cross the waters Monday
morning with a shift to northwesterly winds gusting up to 20 to
25 knots. SCAs will likely be needed late Sunday night through
Tuesday morning, although the latest guidance shows a break
between two separate surges.

Winds will become lighter as high pressure builds overhead
Tuesday. Winds will turn to the south Tuesday night into
Wednesday as high pressure moves offshore, with Small Craft
Advisory conditions possible Wednesday morning through Wednesday
evening.

&&

.TIDES/COASTAL FLOODING...
Southerly flow will persist through tonight. Channeling has
piled water into the northern bay with anomalies rising to 1-1.5
feet. Given little change to the expected water level through
the morning, issued a Coastal Flood Advisory for Annapolis for
this morning`s high tide. Wind direction may be a bit more
variable tonight into Sunday evening introducing further
uncertainty to the tide forecast, though models indicate a
general downward trend. However, elevated water levels are
plausible until a cold front crosses Sunday night into Monday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 PM EDT this evening for MDZ008.
     Coastal Flood Advisory until 1 PM EDT this afternoon for
     MDZ014.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     ANZ530>543.

&&

$$

DISCUSSION...ADS/LFR/DHOF
AVIATION...ADS/LFR/DHOF
MARINE...ADS/LFR/DHOF