051
FXUS61 KLWX 270811
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
411 AM EDT Sun Sep 27 2026
.WHAT HAS CHANGED...
Small Craft Advisories were extended through tonight. Tidal
forecasts remain very uncertain, but additional flooding looks
to largely fall in the minor category. Rain chances and timing
were updated to reflect the latest guidance.
&&
.KEY MESSAGES...
- 1) A Nor`easter brings gusty winds and more showers today
before departing to the northeast Monday.
- 2) Warm and tranquil weather is expected for the middle of
the week before rain chances return by late in the work week.
&&
.DISCUSSION...
KEY MESSAGE 1...A Nor`easter brings below normal temperatures,
breezy conditions, and some rain at times through this weekend.
A Nor`easter is positioned east of New Jersey early this morning
beneath a closed upper low. These features will drift west or
southwest today as an upper level ridge passes across eastern
Canada. Showers along the Chesapeake Bay will continue to expand
westward through the day. There remains some uncertainty with
just how far south and west the rain will reach due to
relatively drier air. Winds are also a bit more northwesterly
today, so some downsloping could help erode the western edge as
well. Rain amounts will be light, generally less than a quarter
inch for most, although locations in northeastern Maryland could
see up to an additional inch of rain. Expect wind gusts to
increase again after sunrise as the gradient wind field rotates
over the area. Peak gusts will again be in the 25-35 mph range
for much of the area. The advancing rain and lower clouds will
limit temperatures for the northern two thirds of the area in
the 60s. Locations in central Virginia will likely rise into the
lower to mid 70s. Tidal flooding will continue to be an issue
through tonight...see separate section below.
The Nor`easter will start weakening tonight as it pivots near
the Delaware Bay. This will lead to decreasing rain chances
tonight, although some patches of light rain or drizzle may
persist. Lows will be in the 50s.
As the blocking ridge departs, the low will be able to start
progressing northeastward Monday while continuing to weaken.
Winds gusts will be much lower than the weekend, and most
locations should remain dry. However, cloud cover will likely
remain stubbornly in place in a broad moisture shield left
behind by the upper low. The current forecast calls for highs in
the upper 60s and lower 70s, but would not be surprised if they
are a bit lower if clouds are thick. As winds shift more
northwesterly, some upslope showers or drizzle will be possible
in the Alleghenies.
KEY MESSAGE 2...Warm and tranquil weather is expected for the
middle of the week before rain chances return by late in the
work week.
As the Nor`easter and accompanying longwave trough continue to
pull away from the Atlantic coast Tuesday and Wednesday,
mid/upper heights begin to build in earnest. These above average
500-mb heights are forecast to run around 585-588 dm as the
transient upper ridge swings eastward toward the Atlantic
Seaboard. Subsidence accompanying this regime favors dry
conditions. However, the moisture left behind by the low may
become trapped beneath the subsidence inversion, so Tuesday will
likely feature more clouds than sun. More sun is likely
Wednesday as surface winds turn southerly. Some fair weather
cumulus likely develop Wednesday and Thursday as instability
increases a bit through the day. However, the forecast is dry
through at least Thursday.
The peak in the warming trend is likely to occur in the mid/late
week period. Global ensemble box-and-whisker plots show fairly low
spread on Wednesday and Thursday and high temperatures return to the
low to perhaps mid 80s. Much of the late week uncertainty revolves
around the increase in shower and cloud coverage. There is some
uncertainty whether the front pushes southward rather quickly or
stalls out nearby. Once this system does push southward,
temperatures are expected to return to more seasonable numbers
for next weekend.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
Additional rain showers will continue to move in from the
northeast through today as a Nor`easter pivots near New Jersey.
The steadiest rain will be at BWI/MTN, where visibility may be
reduced at times, but rain will be lighter elsewhere and may not
reach CHO at all. Lower ceilings will also migrate westward
through the day. They should largely be MVFR, although IFR is
possible later this afternoon and evening at BWI/MTN. NNW winds
will increase again after sunrise, with gusts of 20 to 30 kt
through the day before subsiding this evening.
MVFR ceilings will likely linger through Monday except at CHO,
where any such lower ceilings will likely be brief. Northwest
winds will be much lighter Monday. Stratocumulus ceilings may
persist Tuesday but will likely be VFR as high pressure builds
into the area.
A broad area of surface high pressure remains along the Atlantic
coast on Wednesday into Thursday. This will favor VFR conditions
along with mainly south to southwesterly winds each day.
&&
.MARINE...
Winds have subsided to SCA levels (or less) early this morning
as the Nor`easter has lifted a bit to the north. It will pivot
back to the southwest today but will also start weakening. Some
models show the greatest chance of winds near gale force in the
far northern Bay (near the low) while others show the strongest
winds in the mid bay (longer fetch). However, did not feel
either of these scenarios was worth holding onto a Gale Warning
at this time. The Nor`easter will start weakening tonight and
gradually lift northeastward Monday. Winds will start
diminishing as a result. Extended the Small Craft Advisories for
portions or all of tonight depending on location. Advisories may
need to be extended into Monday, but such conditions would be
much more marginal. Lighter winds are expected Monday night and
Tuesday as high pressure starts building into the area.
With high pressure edging off the coast, marine winds will mainly be
out of the south to southwesterly direction. Gusts should stay below
advisory thresholds on Wednesday. However, some uptick is possible
by Thursday as southerly channeling ensues. This could near Small
Craft Advisory levels, particularly over southern portions of the
Chesapeake Bay.
&&
.TIDES/COASTAL FLOODING...
Water levels are rather erratic, rising quickly in the northern
part of the bay while remaining steady farther south. Surge
guidance has had a hard time figuring out what happens to water
levels through the day, leading to much lower confidence in the
tidal forecast. Did think trends were evident enough that St.
Marys County will not experience moderate flooding, so
downgraded the warning to an advisory. Left the watch for
Annapolis this afternoon/evening due to the large amount of
uncertainty, although only the spread in the Stevens ensemble
suggests that moderate would be possible. As the Nor`easter
weakens tonight and begins pulling away Monday, water levels
should start declining, with the threat of flooding ending by
Monday morning.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 AM EDT Monday for MDZ008.
Coastal Flood Advisory until 11 AM EDT this morning for MDZ014.
Coastal Flood Watch from 1 PM EDT this afternoon through this
evening for MDZ014.
Coastal Flood Advisory until 8 AM EDT Monday for MDZ016.
Coastal Flood Advisory until 6 PM EDT this evening for MDZ017.
Coastal Flood Advisory until 5 AM EDT Monday for MDZ018.
VA...Coastal Flood Advisory until 8 AM EDT Monday for VAZ057.
Coastal Flood Advisory until 11 AM EDT Monday for VAZ054.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ530>534-537-
539>541-543.
Small Craft Advisory until 2 AM EDT Monday for ANZ535-536-538-
542.
&&
$$
DISCUSSION...ADS/BRO
AVIATION...ADS/BRO
MARINE...ADS/BRO
NWS LWX Office Area Forecast Discussion