948
FXUS61 KLWX 060132
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
932 PM EDT Sat Oct 5 2024

.SYNOPSIS...
High pressure to the north will slide offshore early Sunday as
a strong cold front approaches from the Ohio River Valley. This
front will bring renewed chances for showers and thunderstorms
Sunday evening into early Monday morning. Canadian high pressure
builds in behind the front with below normal temperatures
expected for much of next week.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
High pressure will slowly push offshore into early Sunday
morning. Mainly clear skies will prevail along with light winds
leading to a marginal radiational cooling setup. Low
temperatures will be in the upper 40s and lower 50s for most,
with mid-upper 50s in downtown DC and Baltimore. Some low clouds
and/or fog may be possible again, especially to the west of the
Blue Ridge and near the Chesapeake Bay. However, coverage
should be a bit lower compared to earlier this morning. Overall
confidence is lower for fog and low clouds given drier air in
both the mid and low levels. The 00Z KIAD sounding continues to
show decreasing tropospheric moisture with a precipitable water
value of 0.50 inches. Additionally, mid-level RH values have
fallen from 25 percent to 11 percent.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
High pressure slowly drifts off the southern New England and Mid-
Atlantic coast Sunday morning into Sunday afternoon. Dry conditions
will continue with low clouds and patchy fog to start giving
way to mostly sunny skies for the afternoon. Winds will switch
to the south and southwest at 5 to 10 mph yielding highs in the
mid to upper 70s and low 80s east of the mountains.

By Sunday evening, clouds will begin to increase from the west as a
cold front approaches from the Ohio River Valley and Great Lakes
region. This front is associated with a piece of shortwave
energy that will track from the western Great Lakes into eastern
Canada and New England late Sunday night into Monday. The
associated cold frontal boundary with this system will cross our
region late Sunday night into early Monday morning. Current 12z
guidance also remains in good agreement with the timing and
placement of the front which will inhibit the potential for
widespread precipitation as well as severe weather hazards.

With that said, showers and thunderstorms will accompany the
boundary as it passes through. SPC continues to highlight areas
along and west of the Alleghenies for a Marginal Threat (Level 1 out
5) for severe weather. The general focus amongst the 12z CAMS is
back across western PA and north-central WV where the CAPE and
high shear will be maximized. Further east toward western MD and
the eastern WV mountains the environment may be less primed
given the fact that storms will arrive at or just after sunset.
Damaging winds and hail appear to be the primary threats with
any severe storms that can get going Sunday evening into Sunday
night. This activity will continue to weaken as it crosses the
mountains Sunday night into Monday. The highest probabilities
for precipitation east of mountains Sunday night into Monday
morning looks to be in areas along and north of I-66/US-50 where
a stray shower or t-storm cannot be ruled out. Low temperatures
Sunday night will range from the upper 40s in the mountains to
the mid 60s across southern Maryland.

The front kicks east of the area Monday cold air advection funneling
in. Mostly sunny skies are expected with breezy northwesterly winds
gusting up to 20 mph. Highs will be notably cooler, with highs
ranging from the mid 50s in the mountains to the low 70s along
the I- 95 corridor and in Central Virginia.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Surface high pressure builds over the Mid-Atlantic through the end
of the week. Sunny skies, dry conditions, and near to below average
temperatures can be expected each day. Winds remain out of the
northwest throughout the period, blowing 5 to 10 knots with gusts up
to 15 knots expected in the afternoon.

High temperatures each day will be in the 60s for most with higher
elevations staying in the 50s. Overnight low temperatures will be in
the 40s for most with those near the Chesapeake Bay and metro areas
staying in the low to mid 50s. Additionally, those at highest
elevations will dip into the mid to upper 30s.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
The forecast tonight calls for VFR conditions at the D.C. and
Baltimore terminals. Low clouds and fog are possible tonight
although confidence is lower given slightly drier air over the
region. Highest confidence for fog and low clouds would be at
KCHO and KMRB. If any fog or low clouds were to form, it would
quickly burn off after sunrise Sunday morning. VFR conditions
are expected through Sunday evening, although a passing shower
or thunderstorm may be possible Sunday night. Highest convective
probabilities greater than 40 percent remain west of KMRB with
a focus toward KEKN, KPBZ, KCKB, and KCBE. Winds on Sunday will
remain light out of the south at 5 to 10 kts. VFR conditions are
expected behind the front on Monday, with winds turning to the
northwest.

VFR conditions and NW winds blowing 5 to 10 knots are expected
Tuesday and Wednesday at all terminals. Winds could gust 15 to 20
kts each afternoon.

&&

.MARINE...
Winds turn back to the south Sunday into Sunday night ahead of
the next cold frontal boundary. Some channeling is also possible
Sunday afternoon and evening leading to a brief period of near
SCA conditions especially over the open waters of the bay/tidal
Potomac. SCAs are possible on Monday afternoon in gusty NW flow
in the wake of the cold front.

Northwest winds are expected to stay below small craft advisory
criteria on Tuesday as high pressure builds over the area. Winds
near SCA criteria on Wednesday, but are expected to remain below
with gusts up to 15 knots expected.

&&

.TIDES/COASTAL FLOODING...
Tidal anomalies have steadily decreased today as lighter winds have
allowed water to flow down and out of the Chesapeake Bay and Tidal
Potomac River. These anomalies should remain low enough to prevent
most sites from reaching Minor flood through the weekend. Southerly
flow on Sunday may bring a return to minor flooding at some
locations (i.e Annapolis and DC Waterfront). A strong cold
front moves across the area Sunday night, with offshore flow
early next week expected to end the prolonged period of elevated
tides in the area.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...BRO/EST
NEAR TERM...BRO/EST
SHORT TERM...EST
LONG TERM...AVS/EST
AVIATION...AVS/BRO/CAS/EST
MARINE...AVS/BRO/EST
TIDES/COASTAL FLOODING...KJP/LFR