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000
FXUS61 KLWX 110138
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
938 PM EDT Fri Sep 10 2021

.SYNOPSIS...
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High pressure will become centered overhead tonight before
moving offshore tomorrow. High pressure will remain offshore
through early next week. A cold front may approach the area from
the northwest by the middle of the week.
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&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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High pressure is currently centered off to our west over the
Ohio Valley. The high pressure will move overhead tonight. This
will set the stage for ideal radiational cooling conditions,
with clear skies and calm winds in place. With this in mind,
have hedged below both raw NWP and statistical guidance on low
temperatures tonight. We`re currently forecasting low
temperatures in the upper 40s and lower 50s for most locations
with lower to middle 40s in higher elevation mountain valleys,
and around 60 in the downtown DC and Baltimore, where urban heat
island effects will hold temperatures up. Patchy fog overnight
looks pretty limited given the dry air, but can`t rule out some
patchy fog in the most sheltered valleys.
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&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
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High pressure will start off the day tomorrow located directly
overhead. As the day progresses, the high will gradually drift
offshore, allowing light southerly flow to develop in its wake.
Southerly flow will transport slightly warmer air into the area,
but dewpoints will remain in the 50s. Skies tomorrow will be
mostly sunny, and high temperatures will reach into the lower
80s for most. Skies will stay mostly clear tomorrow night, but
temperatures will be noticeably warmer compared to tonight.
Light southerly winds will continue through the night, and low
temperatures will bottom out in the 50s to middle 60s.

High pressure will remain anchored offshore on Sunday as ridging
starts to build in at mid-upper levels. Much warmer air will
advect into the area on westerly flow at 850 hPa/southerly flow
at the surface. Skies will remain sunny with ridging overhead,
but it will be much warmer, with highs in the upper 80s and
lower 90s for most. It will also become notably more humid,
with dewpoints creeping up into the 60s. Our stretch of dry
weather will continue through Sunday night, but it will be
warmer than previous nights, with lows in the mid 60s to low
70s.
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.LONG TERM /MONDAY THROUGH FRIDAY/...
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Upper level ridging continues into Monday as surface high
pressure settles overhead. Heat and humidity return as a
southerly flow ensues. With abundant CAPE albeit no major
forcing, a few late afternoon pop-up showers and/or
thunderstorms may arise across portions of the Alleghenies given
weak terrain circulations. However subsidence should make for
generally dry weather elsewhere. Tuesday appears to be similar
in nature with temperatures in the 90s for most and dew points
in the low 70s. By mid-week a cold front will approach the
region from the west. Guidance is split on the exact timing of
the FROPA which will determine exact impacts for the CWA.
Regardless, at this time, Wednesday into Thursday appears to
have the best potential for more widespread showers and
thunderstorms, some of which may have the potential to be
severe. Any slow moving storms also have the potential to
produce isolated instances of flooding given the abundance of
rainfall as of late. Weak high pressure looks to return for
Friday.
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&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
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VFR thru the period. No fog expected tonight with relatively
dry air. Fog may try to develop tomorrow night as dewpoints
start to cree up.

Winds weak overnight as high pressure builds overhead. Winds
will turn light out of the south-southwest tomorrow, and remain
south-southwesterly on Sunday.

Mainly VFR conditions expected across the terminals Monday and
Tuesday with high pressure in control. Winds will generally be
out of the south.
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&&

.MARINE...
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Winds light tonight as high pressure builds overhead. Winds
will turn southerly tomorrow and remain southerly through
Sunday. SCA gusts in southerly channeling tomorrow night,
possibly lasting into Sunday night.

Relatively quiet weather expected over the waters both Monday
and Tuesday with high pressure in control. However chances for
additional periods of SCA may be required for southern portions
of the bay as a southerly flow ensues.
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&&

.TIDES/COASTAL FLOODING...
Strengthening southerly winds Sat night could result in minor
coastal flooding at Annapolis Sat night into Sunday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 7 PM Saturday to 6 AM EDT Sunday for
     ANZ531>534-537-539>541-543.
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&&

$$
SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...SOUZA
AVIATION...SOUZA/KJP
MARINE...SOUZA/KJP
TIDES/COASTAL FLOODING...LFR