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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 120755
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
355 AM EDT Sun Sep 12 2021

.SYNOPSIS...

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High pressure will remain anchored offshore through much of the
week. A backdoor cold front will approach from Pennsylvania Monday
night, then retreat northward as a warm front Tuesday. Low pressure
may develop near the Carolina coast Thursday into Friday as a
weakening cold front approaches from the Great Lakes.
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&&

.NEAR TERM /THROUGH TONIGHT/...

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Mid-upper level ridge will build over the area today with ridge
axis expected overhead by day`s end. Meanwhile, sfc high
pressure will remain offshore through the middle of the week and
maintain a very warm/hot and increasingly humid air mass.
Mostly clear, except hazy skies, are expected today due to
moderately dense smoke arriving from western fires per latest
HRRR Vertically Integrated Smoke output. Highs today will be in
the upper 80s to near 90. Lows tonight around 70.
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&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...

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Hotter and more humid on Monday as ridge axis remains overhead.
A weak cold front moving through southern NY and northern PA is
expected to trigger sct-nmrs convection across PA Mon evening
which could make it into northeast MD overnight Monday. Kept
20% PoP for areas generally north of I-70.

By Tue afternoon, 925/850 mb dewpoints increase further as ridge
axis shifts offshore resulting in strong instability. Isold
afternoon t-storms may develop west of the Blue Ridge due to
orographic lift and across northern MD due to potential remnant
outflows from overnight convection Monday night.
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&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...

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Details in the medium range period remain mired in uncertainty. What
we do know (or at least have high confidence of) is large scale
ridging over the eastern United States with Bermuda high pressure
anchored offshore at the surface. This will result in a continuation
of above normal temperatures, albeit with a slight cooling trend.

A weakening cold front is progged to slowly approach from the Great
Lakes during the second half of the week. Meanwhile, low pressure
may develop off the Carolina coast. The strength and timing of the
cold front as well as the strength and track of low pressure off the
coast are where the uncertainty stems from. Most ensemble clustering
keeps the low to our east, with a more muted influx of tropical
moisture interacting with the incoming weak front in a sloppy sense
by week`s end. This would result in periods of scattered showers or
thunderstorms rather than an all out washout, though the latter
scenario can`t be entirely ruled out at some point. Subsequent
forecast cycles will refine potential timing and placement of any
more focused precipitation potential late this week into the
upcoming weekend.
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&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...

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Fair weather today and Mon. Slight chance of t-storms Tue
afternoon west of the Blue Ridge and across northern MD may
affect KMRB, KBWI, and KMTN.

Shower and thunderstorm potential may increase later this week as a
weakening cold front approaches and low pressure develops
offshore.
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&&

.MARINE...

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Gusty srly winds through today will begin to diminish late
tonight into Monday morning. SCAs remain in effect today through
12Z Monday. Winds relax Monday into Tuesday.

The chance for showers and thunderstorms looks relatively low
Wednesday, though it may increase Thursday into Friday as a
weakening cold front approaches from the Great Lakes and low
pressure develops off the Carolina coast. Southerly channeling will
likely result in gusts of 20 to 25 knots Wednesday evening and
night. The wind forecast becomes uncertain Thursday into Friday and
depends on the strength of an approaching cold front and the track
of low pressure developing offshore.
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ532-533-537-
     539>541.
     Small Craft Advisory until 2 AM EDT Monday for ANZ530-531-538.
     Small Craft Advisory from 2 AM to 6 AM EDT Monday for ANZ542.
     Small Craft Advisory until 8 AM EDT Monday for ANZ534-543.
     Small Craft Advisory until 9 AM EDT this morning for ANZ536.
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&&

$$
SYNOPSIS...DHOF
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...DHOF
AVIATION...LFR/DHOF
MARINE...LFR/DHOF