Area Forecast Discussion
Issued by NWS Sterling, VA

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544
FXUS61 KLWX 151348
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
948 AM EDT Sun Sep 15 2019

.SYNOPSIS...
High pressure will build in today, behind a cold front that
pushed through the area this morning. The high will shift
southeast away from us Monday as a another cold front drops down
from the north Monday night. Cooler Canadian high pressure will
then build across the region for the remainder of the week.

&&

.NEAR TERM /THROUGH MONDAY/...
Latest surface analysis shows that the cold front has pushed to
the far southern portion of our forecast area. The back edge of
cloudiness has pushed into central VA and southern MD, with only
some residual high clouds elsewhere. Additionally, current
visible satellite and surface obs indicate areas of patchy dense
fogs in the valleys out west, so have issued a statement on
that. Should dissipate in the next hour or so, but until then,
reduced visibilities can be expected in those region, leading to
difficult driving conditions at times.

Latest guidance continues to show some indication of a few
showers along the frontal boundary this morning, but have
lowered chances, as trends have come down it seems, and nothing
is showing up on the radar at this time. Thinking the front will
clear the area late this morning or early this afternoon. Pushed
things a little quicker based off of current frontal position,
so thinking and afternoon thunderstorms stay south of the
forecast are, but can`t completely rule something out in for
southern MD. Otherwise, expect increasing sunshine and
decreasing humidity throughout the day, with highs into the mid
80s.

High pressure shifts across the region tonight. Could be some
patchy fog in the sheltered rural locales, but overall it
shouldn`t be too significant. Likely a lot like we are seeing
this morning in the valleys. Lows mainly in the 60s, with 50s
in the cooler spots.

The high shifts southeast and we get a decent southwest flow to
advect warmer air into the region for Monday. This is occurring
just ahead of another cold front which will drop southward
Monday night. Despite the warm advection, moisture is lacking,
so CAPE is meager. Thus, while a few models show some isolated
showers or storms trying to fire ahead of the front, for now
have kept POPs below slight chance (but above zero). Highs will
be in the upper 80s to near 90, but relatively low humidity (dew
points dropping into the low 60s) should limit discomfort.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
Backdoor cold front crosses the region from north-northeast to
south-southwest late Monday night into early Tuesday.
Temperatures will decline Monday night and may fall for a time
after sunrise on Tuesday before the insolation finally starts to
lift them back up. Unlike the previous backdoor, expect this
front to have less moist of an air mass behind it (more
northerly than easterly flow), so while cloud cover may increase
for a time after frontal passage, expect the clouds to break for
sun later Tuesday. Some guidance shows isolated to scattered
showers or even a t-storm Monday night into Tuesday with the
actual front, but given meager CAPE and shear, have opted to
keep POPs below slight chance (but above zero) for the time
being. Lows will be in the 60s Monday night, with highs in the
high 70s to low 80s Tuesday. Lows Tuesday night with high
pressure building in will be in the 50s to low 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
High pressure across the Great Lakes will move east and build
south into the mid-Atlantic region and remain there for the
remainder of the work week into the first part of the weekend.
Dry weather is expected throughout the long term period. As
winds become more southerly to southwesterly Saturday, high
temperatures will run a little on the warm side.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Should remain VFR through Monday evening. Backdoor front coming
south later Monday night may bring some brief sub-VFR
intervals, most likely cigs, but these likely are transient and
return to VFR by late Tuesday.

VFR conditions expected Wednesday through Thursday night. Winds
east 5 to 10 knots Wednesday, becoming light and variable
Wednesday night. Winds becoming southeast to south 5 to 10 knots
Thursday.

&&

.MARINE...
Weak front crossing the waters may bring gusts close to SCA
levels, but right now expect them to stay just shy. Light winds
expected tonight with high pressure overhead. Winds may increase
a bit on Monday afternoon ahead of another cold front. Best
chance of SCA is Monday night into Tuesday as that front passes
and northeasterly flow strengthens behind it. No marine hazards
expected Wednesday through Thursday night.

&&

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

&&

$$
SYNOPSIS...RCM/CJL
NEAR TERM...RCM/CJL
SHORT TERM...RCM
LONG TERM...KLW
AVIATION...RCM/KLW/CJL
MARINE...RCM/KLW



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