Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 211849
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
249 PM EDT Wed Sep 21 2016

.SYNOPSIS...High pressure will build over the region through early
Thursday then weaken through Friday. A cold front will move
through the area early Saturday. High pressure builds again over
the region early next week.

&&

.NEAR TERM /THROUGH THURSDAY/...A few light showers are seen on
radar over southern MD and the Fredericksburg area, but these are
expected to dissipate early tonight as high pressure builds in and
air mass dries out. Biggest question for tonight is whether high
clouds will thin out and skies become clear. Latest 12Z ECMWF and
HRRR simulated cloud IR imagery show high clouds sticking over the
area around much longer than earlier runs with clearing not
indicated now until after midnight or early Thu. Fog is not
expected as models show sfc dewpoints dropping tonight.

A few high clouds still possible Thu if the ECMWF is correct, but
any high clouds are likely to be thin enough for a mostly sunny
day. High pressure will be in control, although it will be
weakening.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...Weak high
pressure in control during this period. Temperatures are expected
to warm up into the upper 80s and possibly reach 90F in a few
spots on Fri.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...Surface cold front will likely
have passed south of the region by Saturday morning, behing
pushed along by a 1030+ mb high pressure center originating near
Hudson Bay Canada. The center of this high and coolest air will
pass over New England, but much cooler weather is expected over
the Mid-Atlantic as well especially during the second half of the
weekend into early next week.

Onshore flow may result in elevated humidity and low clouds and
drizzle especially early next week. The operational GFS runs have
been the quickest with an approaching cold front next week but have
been trending slower towards a GEFS/EC blend. A slower solution
seems more likely given the large blocky nature of the high pressure
center that will be stationed just northeast of the region next
week. This should keep more substantial rain chances at a minimum
through much of the forecast period.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...VFR conditions next 24
hrs, except for possible 3-5SM mist at KCHO.

Mainly VFR expected Saturday with northerly winds 10 to 15
knots. Sub-VFR possible later in the weekend with lower clouds as
winds become easterly around 10 knots.

&&

.MARINE...Winds will gust to around 15kt in the lower bay through
midday Thu before they begin to diminish.

A pressure surge, aided by northerly channeling, will likely
push winds into Small Craft Advisory territory on Saturday. Winds
should gradually diminish and veer to the east Saturday night into
Sunday.

&&

.TIDES/COASTAL FLOODING...

Elevated water levels persist through the rest of the week due to
low pressure off the Carolina coast. Coastal flooding threat is low
through Friday.

&&

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

&&

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



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