151
FXUS61 KLWX 051420
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
920 AM EST Thu Mar 5 2026

.WHAT HAS CHANGED...
Starting to see some dense fog lift, but it will be slow to
dissipate this morning. SPC has added a Marginal Risk for severe
thunderstorms this afternoon/evening.

&&

.KEY MESSAGES...
-1) A meandering front will bring highly variable temperatures,
 occasional rain/t-storm chances, and nighttime fog through
 Saturday.

-2) Unseasonably warm conditions continue into next week with
 potential for a strong cold front to reach the area late
 Wednesday or Thursday.

&&

.DISCUSSION...
KEY MESSAGE 1..A meandering front will bring highly variable
temperatures, occasional rain/storm chances, and nighttime fog
through Saturday.

A Dense Fog Advisory remains in effect through 10AM, but may
need to be expanded in some areas depending on how fog persists
in the next hour. The latest obs are starting to show some
improvement east of the Blue Ridge as fog lifts to low stratus,
but still seeing a lot of 0 visibility obs in the Shenandoah
Valley (the more likely location to need an expanded Dense Fog
Advisory). Additionally, a stream of showers has moved across
the frontal boundary in western MD. These showers will continue
moving east, but mostly remain along/north of I-70.

Low pressure will be moving toward the upper Ohio Valley today
while ridging attempts to build across the southeastern states.
This may help push the front northward today, but it does appear
it will struggle to lift northeast of the Potomac River as a
weak pressure gradient (and therefore winds) will be unfavorable
for scouring out the cool dense air and thick low clouds. Therefore,
expect temperatures to range from near 50 in northeastern
Maryland to the upper 70s in central Virginia. Depending on how
much fog/low clouds lingers this morning, adjustments to the
temperature forecast will be needed. Most of the uncertainty is
right along edge of the CAD, which models have wavering around
the Potomac River this afternoon.

As the associated shortwave trough approaches, it appears
showers and thunderstorms will spread eastward across the
Appalachians late this afternoon and evening, with the best
forcing across northern parts of the area. SPC has added a
Marginal Risk of severe weather in the Potomac Highlands where
the latest high-res models show instability will be greatest.
SBCAPE values around 600-1000 J/kg is possible, and that is
enough to support isolated thunderstorms moving in from the OH
Valley. Conditions overall are marginal, but a strong storm or
two capable of producing isolated wind damage is possible. To
the east, instability will be much lower and elevated. So could
see a few rumbles of thunder in the metro areas this evening,
but low level stability will make lightning the only hazard.

As the low passes off the Mid-Atlantic coast tonight, high
pressure moving toward the Canadian Maritimes will likely shove
the front back south, resulting in the reemergence of low
clouds, fog, and cooler temperatures. Dense fog is possible but
could depend whether a light northeast winds persists. While
showers will dwindle the second half of the night, some patchy
drizzle could emerge.

The backdoor cold front will separate an increasingly warm
airmass building northward from the southeastern U.S. on Friday
A 30 to 35 degree spread in temperatures could exist from
northeast MD to central VA. The latest guidance is trending to a
typical wedge set up where low clouds and cooler temperatures
remain farther south east of the Blue Ridge (potentially to near
Charlottesville) while in the Shenandoah Valley the warm air is
able to make inroads to about I-66. Scattered showers and
perhaps a thunderstorm may develop Friday afternoon, especially
west of the Blue Ridge, as a subtle shortwave trough passes
overhead during peak heating. Some dense fog could form again
Friday night as higher dew points attempt to start advecting
back northward.

Another low pressure system will be moving through the Great
Lakes early Saturday, tightening the pressure gradient with high
pressure off the southeast coast. The increased southerly flow
will have the best chance of lifting the wedge front northward
and bringing 60s and 70s (to near 80) to much of the area.
However, the NAM and AI Euro/GFS keep the wedge firmly in place
across the eastern half of the forecast area, so prepare for
potential forecast changes here. Forcing from the frontal system
will approach during the late afternoon or evening. This timing,
along with the amount of instability able to build northward
(likely on the weaker end of the spectrum), will be important to
thunderstorm chances. With sufficient wind fields in place, the
Storm Prediction Center has highlighted areas west of the Blue
Ridge in a Marginal Risk for thunderstorms with gusty winds.
However, probabilities for severe weather are highest across the
upper Ohio Valley.


KEY MESSAGE 2...Unseasonably warm conditions continue into next
week with potential for a strong cold front to reach the area
late Wednesday or Thursday.

Cold front moves eastward Sun likely confining rain shower chances
to southern and eastern areas. Winds do become more WNW behind the
front, but remain light. The front kind of washes out near or south
of the FA by Sun night, before perhaps returning north into Mon.
Some guidance has the front moving back north Mon with low end rain
shower chances while other guidance is dry. It does appear much
of the eastern US gets into deep southwesterly flow with high
model agreement on temperatures reaching the 60s and 70s.

Next sig wx maker likely comes in the late Wednesday to early
Thursday time frame with potent March cold front which will
bring an abrupt end to the warmth.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
LIFR ceilings and dense fog continue through late morning, then
slowly lift this afternoon. There is uncertainty to how quickly
conditions improve as the low level stability keeps clouds
longer than guidance shows.

This afternoon will definitely see some improvements from
MRB/IAD/DCA points south (where winds may turn southeast or
south for a time) with BWI/MTN hanging on to IFR cigs all day
with an easterly wind. More showers and perhaps even an embedded
thunderstorm will cross the northwestern terminals during the
late afternoon and evening. Chance for thunderstorms at the
metro terminals is low enough (20 percent or less) to leave out
of the TAF for now.

IFR to LIFR conditions in low ceilings and/or fog will spread
back across the area tonight. CHO could be near the southern
boundary, however, and could go either way. It`s now looking
like these low ceilings will have trouble lifting northward
Friday, with perhaps only minimal diurnal increases to the cloud
base with continued light east to northeast winds. Some
scattered showers are possible Friday afternoon and evening but
with minimal impact compared to the ceilings. Expect ceilings to
lower again Friday night.

Greater chance for improving conditions Saturday but not
guaranteed at BWI/MTN. Showers and thunderstorms will approach
from the west late in the day, with MRB having the greatest
chance of a thunderstorm.

VFR condtions Sun once the front moves east. Behind the front,
lighter winds out of the W/WNW. These turn more SW`ly into Monday,
but remain light with continued VFR conditions.

&&

.MARINE...
A quasi-stationary boundary will lift slightly northward today,
dropping south tonight, then lifting north Saturday. A cold
front will try to cross the waters late Saturday into Sunday
before washing out over the region early next week.

Dense fog slowly dissipates and lifts over the waters late this
morning, though some could linger into the early afternoon.
Dense fog is likely to be an issue again Friday and Saturday
mornings as well as winds remain light. The northern Chesapeake
Bay may largely keep east to northeast winds through Friday
night, while areas south of Washington DC and the Bay Bridge
could flip to southerly at times. Winds should remain below
advisory criteria.

Winds will gust to near SCA criteria out of the SW on Saturday.
However, thinking that the continued cold waters in comparison to
warmer air temperatures could confine the threat primarily to
interior waterways, and that is assuming the front can fully
lift northward.

FROPA Sun during the morning hours. Behind the front, winds go out
of the WNW, but remain below SCA levels. For Mon, winds turn more
out of the SW while remaining below SCA levels.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Dense Fog Advisory until 10 AM EST this morning for DCZ001.
MD...Dense Fog Advisory until 10 AM EST this morning for MDZ003>006-
     013-014-016>018-502>506.
VA...Dense Fog Advisory until 10 AM EST this morning for VAZ026>031-
     036>040-050-051-053>057-501-502-505-506-526-527.
WV...Dense Fog Advisory until 10 AM EST this morning for WVZ050>053-
     055-504.
MARINE...Dense Fog Advisory until 10 AM EST this morning for ANZ532>537-
     541>543.

&&

$$

DISCUSSION...ADS/CPB
AVIATION...ADS/CPB
MARINE...ADS/CPB

NWS LWX Office Area Forecast Discussion