Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

657
FXUS61 KLWX 291341
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
941 AM EDT Wed Apr 29 2026

.WHAT HAS CHANGED...
Made some slight increases in the tidal forecasts overall to
reflect the recent observational trends. See the Tides/Coastal
Flooding section below for more details. Otherwise, no changes,
as the line of showers moving in form the west is on track thus
far. Will have to wait and see how things recover thereafter to
assess the severe threat for later today.

&&

.KEY MESSAGES...
1) Showers and thunderstorms will accompany a strong frontal
system through this evening.

2) Well below normal temperatures are expected this weekend into
early next week, with frost and/or freezing temperatures
possible.

3) A persistent upper low may bring additional showers to the
area on Thursday and Friday.

&&

.DISCUSSION...
KEY MESSAGE 1...Showers and thunderstorms will accompany a
strong frontal system through this evening.

The latest surface analysis depicts a slow-moving warm front
from the eastern WV panhandle down through eastern NC, with the
cold front still out over the Ohio Valley. While the primary
low is well into Canada, a secondary low is developing in the
Ohio Valley as well, which will need to be closely monitored
today. A line of heavy showers and a few thunderstorms has
actually been gradually filling in as it moves east towards the
Allegheny Front this morning. While no severe weather is
expected from this, it may very well play a huge role in the
impending severe weather threat later this afternoon/evening.
There is at least some instability where this line of
showers/storm currently resides, on the order of 250-500 J/kg.
However, as the move east of the Allegheny Front, that number
quickly drops to zero, and that is due to the abundance of low
clouds that have plagued the region this morning. This should
result in these now robust showers/storms dissolving into fairly
benign showers, mainly west of the Blue Ridge, through Noon or
so.

The major question mark of the day is whether or not the morning
low clouds and showers will erode enough to support sufficient
destabilization of the atmosphere during the core heating hours
this afternoon. While the current forecast package calls for
highs in the mid 60s to low 70s, this might be somewhat
optimistic based on the mentioned issues. However, if we do
manage to get enough clearing, other parameters favor some
severe weather along and just ahead of the cold front, which
will push through later.

A formidable cold front is forecast to reach the Blue Ridge
Mountains by the early evening. While instability may be meager,
the deep-layer shear running between 40 to 50 knots could easily
make up for this deficiency. Further, many forecast soundings
show enlarged cyclonically curved 0-3 km hodographs. This is
likely to be enhanced by the aforementioned secondary low moving
directly overhead. If storms were to root into the boundary
layer and remain discrete in nature, some supercell development
cannot be ruled out. This would support a risk of an isolated
tornado. However, this appears to be the ceiling of this event
with the more likely scenario favoring damaging wind gusts along
and ahead of the cold front. Per the latest Storm Prediction
Center (SPC) outlook, a Marginal Risk continues across a bulk of
the region outside of far northeastern Maryland. On the
rainfall side of the equation, a broad axis of 0.50 to 0.75
inches of rain is expected. This should prove to be more
beneficial in nature given the longstanding rainfall deficit.

Showers finally exit into the Eastern Shore after midnight.
Drier conditions ensue along with a shift to northwesterly
winds. Low temperatures tonight should fall into the 40s to low
50s, with spotty upper 30s along the Allegheny Front.


KEY MESSAGE 2...Multiple nights of frost/freezing conditions possible
late week into the weekend.

The upper level pattern will remain relatively stagnant this weekend
as a deep upper low continues to circulate off to our north. Upper
troughing at mid-upper levels and well below normal temperatures at
lower levels will persist along the East Coast during that time.
High temperatures this weekend will generally be in the upper 50s to
lower 60s beneath mostly cloudy skies. Depending on how the surface
pattern sets up, frost and/or sub-freezing temperatures may be
possible early Saturday morning, and then again Saturday night.
Locations to the west of the Blue Ridge should have the greatest
chance of seeing below freezing temperatures. With a relatively dry
airmass in place, most solutions favor conditions remaining dry
through the weekend, although a popup shower or two can`t be ruled
out during the afternoon hours beneath the upper low. Forecast
uncertainty increases a bit by Monday and Tuesday, but most
solutions favor the upper trough moving out and a resultant warming
trend in temperatures.


KEY MESSAGE 3...A persistent upper low may bring additional
showers to the area on Thursday and Friday.

Behind the mid-week frontal system, the pattern aloft will see
an expansive upper low overspread the Great Lakes into the
northeastern U.S. This comes with below average temperatures as
well. For late April/early May standards, 500-mb height
anomalies are fairly impressive being in the 1.5 to 2 standard
deviation below average range. General upward motions underneath
this circulation will aid in some shower development each day
through Friday.

For Thursday, the air mass behind the cold front will be dry and
breezy with northwesterly gusts to around 20 to 25 mph.
Therefore, any mention of showers is confined to along/west of
the Allegheny Front where upslope flow will locally enhance
lift. If the showers occur early enough, some of the highest
elevations could even see a few snowflakes mixing in.

By Friday, the center of the upper low moves across southeastern
Ontario. A series of perturbations circulating cyclonically
around this trough will help bring isolated/scattered showers to
the area. This will particularly be the case during the
afternoon hours given enhanced lift. Forecast soundings show
fairly high bases to these showers, so evaporative cooling
effects below could yield some brief gusty winds. A few showers
could linger into the evening but expect a downward trend with
the loss of heating. A chilly night lies ahead as lows fall into
the upper 30s to mid 40s (low/mid 30s across the Alleghenies).
With the 1991-2020 median last freeze date on May 1 across the
Alleghenies, frost/freeze products will commence.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
Light southeasterly flow continues early this morning with
widespread low stratus in place. Much of these feature cloud
bases around 1,000 to 2,500 feet (MVFR). With low clouds in the
picture today, restrictions are expected throughout the day.
Rain showers, currently located along a line in eastern WV,
arrive late this morning into the early/mid-afternoon before a
stronger round of storms may impact the terminals between
21Z-01Z. The degree of severe weather threat is more unknown,
but these cells will have the potential of producing
strong/gusty winds this evening.

Any convective threat winds down by late this evening while
winds shift to northwesterly overnight behind the cold front.
VFR conditions return into the night.

For Thursday and Friday, expect mainly VFR conditions. Breezy
northwesterlies are likely to start off with afternoon gusts to
around 20 to 25 knots. Any shower chances are likely relegated
to the Allegheny Front. An upper low to the north will bring a
better shot of isolated/scattered showers on Friday. These could
support a few brief restrictions and some locally gusty
downdraft winds. Otherwise, the overall winds will remain out of
the west.

VFR conditions are expected at the terminals this weekend. Winds are
forecast to be out of the northwest on Saturday, and then west on
Sunday.

&&

.MARINE...
Winds will increase through the day with Small Craft Advisories
in effect for all waters starting at 11 AM. These remain in
place until early Thursday morning as winds shift to
northwesterly behind tonight`s cold front. Additionally, this
front will pose a risk of some stronger storms which may require
some evening Special Marine Warnings. Such storms push into the
Eastern Shore by after midnight. There may be a brief overnight
"lull" in winds, falling below SCA criteria for a few hours, but
expect those to increase Thursday morning yet again.  =

Breezy northwesterly winds are expected on Thursday with Small
Craft Advisories likely needed through much of the day. Winds
begin to decrease into Thursday night as well as Friday with a
shift to westerlies. An upper low will aid in some shower
development on Friday, many of which will be high based. Some of
these could produce locally gusty winds so Marine Weather
Statements may be needed at times.

Sub-SCA level northwesterly winds are expected over the waters on
Saturday. Westerly gusts may reach low-end SCA levels on Sunday.

&&

.TIDES/COASTAL FLOODING...
Southeasterly flow continues to keep anomalies elevated at most
of the tidal sites. Many locations will reach Action Stage
during high tide through tonight, with Minor tidal flooding
expected at Annapolis. Annapolis may even come pretty close
during the afternoon "lower" high tide cycle, if trends
continue, but not enough confidence yet to issue an Advisory at
this time. A few other tidal sites like Alexandria, Dahlgren,
and Havre de Grace could get close during the higher of the two
astronomical high tides this evening as well.

Water levels begin to drop off by Thursday as winds shift to
northwesterly.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 7 PM EDT Thursday for ANZ530>543.

&&

$$

DISCUSSION...BRO/CJL/KJP
AVIATION...BRO/CJL/KJP
MARINE...BRO/CJL/KJP