Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 210116
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
916 PM EDT Tue Sep 20 2016

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

&&

.NEAR TERM /THROUGH WEDNESDAY/...
High pressure will continue across much of the Mid-Atlantic region
tonight. A surface low will remain nearly stationary across the
southern Outer Banks into Wednesday. Light northeast flow will
continue tonight.

Showers should stay across the southern Chesapeake Bay tonight.
Mid-high level thin clouds are expected tonight across most of the
region with the exception of southern MD and surrounding waters. Fog
is expected to develop across low lying areas across the
Shenandoah Valley and Central Foothills. Fog will be less
widespread than last night however some visibilities may become
less than a mile. Fog will taper off shortly after sunrise
Wednesday.

High pressure will move southward Wednesday and an isolated shower can`t
be ruled out across the Central Foothills and Southern MD however
chance is low as drier air moves southward Wednesday. Temps in
the low to mid 80s expected.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
Fog appears less likely Wed night as models show sfc dewpoints
dropping Wed night. High pressure will continue to hold over the
area with fair weather conditions.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Main weather story during the long term will be first real taste
of autumn...as a cold front drops southward through the area
Saturday.

Friday into Saturday: Remaining warm prior to frontal passage, with
highs 5-10 F above climatological normals. Dewpoints in the 60s will
be just high enough for at least a hint of humidity. Moisture-
starved cold front moves through the area during the day
Saturday...with only a limited chance of precipitation (anything
that manages to develop would be light and isolated).

Sunday through Monday: Pleasant weather expected behind the front as
high pressure builds into the area and dewpoints fall into the
U40s/L50s. Temperatures also cool to near seasonable values with
highs generally in the 70s and lows in the 50s/60s. Dry weather
expected during this time.

Tuesday: Next front approaches the region Tuesday. Quality moisture
appears to be lacking again...so currently expecting limited
precipitation chances.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
Potential for fog development exists again tonight in Wednesday
morning. Best chance will be across KMRB however confidence is low
taking it down to LIFR at this time. At this time...MVFR vsbys
expected at CHO and IAD with a chance at BWI. VFR conditions
expected at DCA.

VFR conditions expected Friday through the weekend as a mostly dry
cold front passes through the area. Winds shift from southerly to
northerly with frontal passage Saturday into Sunday.

&&

.MARINE...
NE winds have been flirting with 18-20kts across the lower Tidal
Potomac and adjacent Chesapeake Bay zones this evening. A SCA is
in effect this evening. Winds are expected to diminish overnight
and into Wednesday.

NEly flow 10-15kt through Thursday as low pressure lingers along the
Carolina coast.

Winds forecast to remain below SCA values Friday. Winds could increase
near SCA values near/behind cold front Saturday into Sunday.

&&

.TIDES/COASTAL FLOODING...
Possible minor coastal flooding at Alexandria/DC this evening
however tidal anomalies should decrease towards the high tide and
therefore water levels should stay under flood stage. Confidence
is low, so will closely monitor.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Wednesday for ANZ534-537-
     543.

&&

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



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