-- Discussion containing changed information from previous version are highlighted. --
467
FXUS61 KLWX 150838 CCB
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Sat Mar 15 2025

.SYNOPSIS...
A stalled front south of the area will lift north as a warm front
tonight. A strong cold front will cross the area Sunday evening.
High pressure will build in from the west early next week. The next
cold front may reach the area by Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure has moved offshore, but a front remains stalled to the
south this morning. The powerful low pressure system is lifting
toward the upper Midwest with an arc of convection out ahead of it.
Locally, marine stratus has overspread areas east of the Blue Ridge
beneath cirrus, while spilling westward through the lower elevations
to the north. Visibility is reducing in fog and drizzle from east to
west. While some locally dense (1/4SM) fog can`t be ruled out, most
guidance is favoring low ceilings instead. The stratus will
gradually lift through the day, but may struggle to dissipate east
of the Blue Ridge. Have therefore favored cooler guidance in this
area with temperatures remaining in the 50s for most. To the west,
60s will be more common, perhaps locally 70, with gustier southeast
winds. It appears that any precipitation through the day will be
limited to the patchy drizzle, although a stray shower could occur
across the terrain this afternoon.

Tonight, the pressure gradient will strengthen and a strong low
level jet will overspread the area. This should help the warm front
lift north, with some areas seeing steady and rising temperatures
overnight. With 40-50 kt forecast near and above 2000 ft, Wind
Advisories have been issued for the higher elevations that extend
into Sunday. These may eventually need to be expanded to more zones,
especially by Sunday morning.
Moisture advection will likely result in a return of low ceilings
(instead of fog due to the elevated surface winds...although some
could form along the cool waters of the bay). A few light showers
may also occur, especially over the mountains.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Forcing from the dynamic trough and strong wind fields will
overspread the area Sunday. Associated bands of showers will
gradually move across the area, as steering flow and shear vectors
will be nearly parallel. This could lead to some moderate to heavy
rainfall rates, although individual elements will be quickly moving.
Forecast rain amounts range from 0.5-1 inch for most areas. Given
recent dry conditions, the flooding threat will be minimal besides
possible poor drainage issues. While the instability and resultant
thunderstorm potential remain uncertain, it won`t take much to mix
down damaging winds, particularly with northeastward moving line
segments/discrete cells, and a large part of the forecast area
remains in a Slight Risk of severe thunderstorms from SPC. While a
tornado or two can`t be ruled out due to strong low level shear,
forecast sounding indicate hodographs may straighten as the main
convection nears. Timing has shifted slightly later, affecting most
areas (especially near and east of the Blue Ridge) during the
afternoon, which could favor surface based convection.

Before the showers arrive, gradient wind gusts could increase to 30-
50 mph, especially west of the stabilizing influence of the cooler
Chesapeake Bay. Uncertainty continues since winds are more difficult
to mix down in warm advection regimes as it is (air is rising
instead of descending), but models also show potential mixing depth
issues as low clouds may linger while the low level jet is
strongest. This may ultimately temper the severe weather threat as
well.

Even though the cold front and thunderstorm risk should be exiting
to the east by midnight, the upper level trough is lagging, and
guidance is trending toward additional showers developing behind the
front which could last into Monday morning, especially for eastern
areas. Clouds likely last longer into Monday as well until the
trough axis moves east. The window for upslope precipitation is
short with limited moisture, but a little snow is possible along the
Alleghenies by Monday morning. Otherwise, expect NW winds gusting 20-
30 mph Monday with cooler (but still slightly above normal)
temperatures. Seasonable weather is expected Monday night as winds
diminish.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Mid-level ridging along the Eastern Seaboard looks to maintain dry
and very warm conditions across our area Tuesday and Wednesday of
next week. Highs in the 60s Tuesday reach the 70s Wednesday, with
overnight lows 40s. A weak surface high that pushes offshore ushers
in the return of light southerly flow, though not expecting much
moisture return until later in the week as dew points stay in the
30s to 40s.

Toward the end of next week a strong upper trough is forecast to
move from the Central Plains toward the Great Lakes and Mid-
Atlantic. The current model guidance indicates the main energy
associated with that trough digs well to our north/west (OH Valley
to western Great Lakes). Though, a secondary trailing shortwave that
remains south of the main trough is more likely to move toward the
Mid-Atlantic. This feature also drags an associated cold front
through the area Thursday night into Friday. This is likely the next
chance for showers and possibly some thunderstorms for our area.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
Marine stratus has spread across the terminals this morning, with
ceilings decreasing through MVFR to IFR. There are still fairly high
probabilities of LIFR for several hours around daybreak. Visibility
is slowly reducing in mist and drizzle from east to west...though
recent guidance is trending away from fog (1/2SM) for most
terminals. These clouds should gradually lift during the late
morning and early afternoon, although there is uncertainty how
quickly it does so. There is some potential for the metro terminals,
especially BWI/MTN to keep MVFR ceilings. A front stalled to the
south will lift north tonight. The fact that winds will likely
increase into the 10-15 kt range means that the moisture advection
will likely result in more ceilings (likely MVFR) versus fog,
although BWI/MTN could have some fog closer to the cooler waters of
the bay. With the amount of mixing uncertain, have included LLWS in
the TAFs as winds will be 40-50kt at 2kft. These conditions will
likely persist into Sunday morning, with some uncertainty with how
quickly ceilings will lift. There is at least a chance of MVFR until
convection arrives during the afternoon and evening.
Multiple bands of convection will bring a threat of moderate to
heavy rain and strong to severe winds, even if lightning is somewhat
sparse. Outside of thunderstorms, S-SW gradient winds will gust 25-
35 kt.

The cold front will cross Sunday night with a wind shift to the NW.
The timing of the upper level system is slower, and some showers and
sub-VFR conditions may linger into Monday morning.
Otherwise expect NW wind gusts of 20-25 kt Monday.

VFR conditions are likely through the middle of next week with light
southerly winds in place.

&&

.MARINE...
A stalled front will remain south of the area today while high
pressure moves offshore, resulting in light E to S winds. Patchy fog
and drizzle could reduce visibility through the morning hours.

The front will lift north this evening, leading to increasing
southerly flow. Small Craft Advisories have been issued, though
there is some uncertainty with how quickly the stronger winds start
mixing down. Fog may also develop as higher dew points move over the
cool waters.

At least Small Craft Advisory conditions continue Sunday ahead of a
frontal passage in strong SW flow. Winds may approach gale force,
with the highest (though still uncertain) chance of this occurring
on the middle and upper tidal Potomac River. A Gale Watch has been
issued for these zones. The cool Chesapeake Bay waters will likely
keep the atmosphere more stable, and this is apparent in model wind
forecasts. However, conditions will be close, and future shifts may
need to upgrade the advisory to a warning. As showers and possible
thunderstorms move across the waters Sunday afternoon and evening,
Special Marine Warnings may be needed due to the threat of strong
winds. There may be a break in the winds until the cold front
crosses overnight, then advisory conditions will return in NW flow.
Gusts to 25 kt are possible Monday before gradually diminishing
Monday night.

Marine conditions are forecast to be mostly favorable during the
middle of next week with high pressure over the region. Some gusty
north winds early Tuesday morning quickly diminish by early
afternoon. Then winds remain below SCA levels through Wednesday
night. However, will have to monitor for the possibility of
southerly channeling in the middle Chesapeake Bay Tuesday and
Wednesday evenings, where gusts could approach 15 knots.

&&

.TIDES/COASTAL FLOODING...
Southeast to south winds through the weekend are expected to result
in steadily rising tidal anomalies across the Chesapeake Bay and
Tidal Potomac River. The strongest south winds are expected tonight
through Sunday evening. As a result, sensitive locations at
Annapolis, Havre de Grace, and DC SW Waterfront are likely to reach
minor flooding during the Sunday morning and Sunday evening high
tide cycles. Most other locations will hit Action Stage during those
high tides. A cold front sweeps through Sunday night, bringing
offshore winds and rapidly falling tidal anomalies.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...None.
MD...Small Craft Advisory from midnight tonight to 6 PM EDT Sunday
     for MDZ008.
     Coastal Flood Advisory from 6 AM to 11 PM EDT Sunday for
     MDZ014.
VA...Wind Advisory from midnight tonight to 2 PM EDT Sunday for
     VAZ503-507-508.
WV...Wind Advisory from midnight tonight to 2 PM EDT Sunday for
     WVZ501-505.
MARINE...Small Craft Advisory from midnight tonight to 6 PM EDT Sunday
     for ANZ530-531-538-539.
     Small Craft Advisory from 8 PM this evening to 6 PM EDT Sunday
     for ANZ532>534-537-540>543.
     Small Craft Advisory from midnight tonight to 6 AM EDT Sunday
     for ANZ535-536.
     Gale Watch from Sunday morning through Sunday afternoon for
     ANZ535-536.
-- End Changed Discussion --

&&

$$

SYNOPSIS...ADS
NEAR TERM...ADS
SHORT TERM...ADS
LONG TERM...KRR
AVIATION...ADS/KRR
MARINE...ADS/KRR
TIDES/COASTAL FLOODING...KRR