Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 160751
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
351 AM EDT Mon Oct 16 2017

.SYNOPSIS...
A cold front is pushing southeast of the Mid Atlantic today.
High pressure will return by tonight and hold through next
weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Cold front currently extends across the southern tip of St.
Marys County. However, frontogenetical forcing aloft is
resulting in fairly widespread showers behind the surface front.
Guidance has had a good handle on this and is showing a much
slower exit than previous forecasts. The last of the showers may
not finally exit southern Maryland until around noon, give or
take a couple hours. Behind this band of rain, there will be
some clearing, although scattered to broken cumulus will likely
persist in the cold air advection regime. It will also be breezy
with gusts of 20-30 mph. Temperatures will likely keep falling
through the morning, then rebound a little during the afternoon.
Calendar day highs likely occurred during the overnight, with
daytime highs in the lower to mid 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
After this evening, it`s mainly a temperature forecast through
the middle of the week, with attention paid to frost/freeze
concerns. High pressure will move in from the west tonight and
then remain directly over the region through the middle of the
week. Clouds will be minimal and winds light.

Have trended forecast toward colder guidance for overnight lows
given what should be fairly good radiational cooling
conditions. Tonight may be a little tricky since some wind is
likely to linger, but it does look like calmer conditions are
likely toward dawn. A Freeze Watch will be in effect for
portions of the highlands tonight. Would not be surprised if
there were some pockets of near- freezing temperatures in the
rest of the western valleys as well. Will let the day shift
determine which areas will need a Frost Advisory, with locations
west of the Blue Ridge looking most favorable.

Temperatures will gradually moderate through the middle of the
week, but not before another potential frost/freeze for outlying
areas Tuesday night. Daytime highs will remain in the 60s
Tuesday, but inch into the 70s for some areas on Wednesday.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
High pressure is expected to dominate through the long term,
resulting in dry conditions through the weekend. Temperatures
will be moderating as we head through time as ridging builds
aloft and southwesterly flow comes to dominate as the high
slowly pushes east off the coast. We are heading deeper into
autumn, with diminishing sunlight and sun angle, so the level of
warmth we saw early in the month is not likely...our current
level of sunshine is about the same we would get in February.
However, enough warmth will build northward from the tropics to
make above normal temperatures very likely late in the week and
this weekend (normals now having fallen into the 60s).

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Brief MVFR cigs are possible (except MRB) as a post-frontal
band of showers moves across the area early this morning. The
rain itself should be light and end in the 10-14Z time frame
from west to east. Gusty NW winds of 20-25 kt will be possible
during the daylight hours today, with skies trending toward
scattered/broken cumulus.

High pressure begins moving over the area tonight and will
remain in control through the middle of the week. No aviation
concerns are expected.

No significant aviation concerns are expected late in the week,
though patchy fog or areas of low clouds can`t be entirely ruled
out during the late night and early morning hours.

&&

.MARINE...
A cold front has nearly cleared the local marine area with
northwest winds being established. Light rain will take longer
to exit though. Gusts may be sporadic through sunrise, but winds
of 20-25 kt will be common through the day. Have extended the
times of all segments of the Small Craft Advisory, since it
looks like mixing will only slowly decrease this evening, and
20-25 kt winds aloft will remain over the warm waters of the Bay
into Tuesday morning. By noontime on Tuesday, high pressure
will be building overhead, and lighter winds can be expected
through the middle of the week.

Significant marine hazards are not anticipated to be a concern
Thursday or Friday, though southerly channeling resulting in a
small craft advisory can`t be entirely ruled out.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...Freeze Watch from late tonight through Tuesday morning for
     VAZ503-504.
WV...Freeze Watch from late tonight through Tuesday morning for
     WVZ501-502-505-506.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ531>533-
     539>542.
     Small Craft Advisory until midnight EDT tonight for ANZ530-535-
     536-538.
     Small Craft Advisory until noon EDT Tuesday for ANZ534-537-543.

&&

$$
SYNOPSIS...RCM
NEAR TERM...ADS
SHORT TERM...ADS
LONG TERM...RCM
AVIATION...ADS/RCM
MARINE...ADS/RCM



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