Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 090218
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
918 PM EST Thu Dec 8 2016
High pressure will build east from the Great Plains through
Saturday before moving off the Mid-Atlantic coast Sunday morning.
A cold front crosses the area Monday followed by a reinforcing
cold front Wednesday.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 9pm, a 1050mb surface high is centered over the NErn corner
of Alberta. A surface ridge extends from there all they way to the
central Mid-Atlantic; underneath a broad upper trough. This high
center will build over the area trough Saturday (though it will
only be 1034mb or so by then). West to northwest winds became
gusty this afternoon and have increased since. A few gusts of 35
to 40 mph gusts have been reported; mainly over the northern
third of the CWA. A 47 mph gust occurred at 8:30pm at KW99
(Petersburg, WV). This looks to be isolated, so a wind advisory is
not anticipated at this time. However, it will remain breezy
overnight due to cold air advection.
Upslope snow showers are very light right now; half to one inch
accumulation overnight west of the Allegheny Front. Mid- level
clouds are producing virga over west- central Maryland this
evening and should continue to for a few more hours. Flurries
possible at higher elevations.
Minima primarily in the mid 20s...around 30 in the cities...teens
in the Highlands.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
High pressure to be in control of the weather Friday-Saturday
night. Temps will be several degrees below normal (Mid 40s/upper
20s). East of I-95 will struggle to reach 40...35-40 west of I-95
to the Highlands...20s in the Highlands. Wind chills will make it
feel more like 25-30 in most locales. Snow showers expected to
continue in the Highlands through at least Friday night.
A cold Friday night with lows in the 20s everywhere except the
colder Highlands. Highs Saturday will be quite similar to Friday.
High pressure will settle over the region Saturday night providing
good radiational cooling conditions. Lows primarily in the lower
to mid 20s.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Surface high pressure overhead Sunday will move offshore as a
southerly flow builds over our region. A weakening upper level
shortwave could bring precipitation north of the area, but cannot
rule out precipitation reaching out over the CWA. If it does,
temperatures may be cold enough, mainly at higher elevations, to
see some type of frozen precipitation... but there is still
uncertainty on this.
Warm front moves over our area Sunday night, bringing a chance of
precipitation as a low pressure moves from the Mid-West into the
Great Lakes. Wintry precipitation possible as temperatures may be
near or below freezing in some areas before the warm front moves
through. The low will continue its track northeast and push a cold
front over our region Monday into Tuesday... with rain more likely
ahead of the front. Conditions will be drying Tuesday into Tuesday
night. Guidance disagrees for Wednesday and Thursday with GFS
bringing another cold front on Wednesday, increasing the chance of
precipitation over our area... then dry conditions on Thursday.
The Euro is drier with a couple of disturbances bringing a chance
of precipitation to the area.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR expected tonight through Saturday night. Strong NW winds
with gusts 25 to 30 kt through midnight and again Friday.
Mainly dry/VFR conditions on Sunday as high pressure moves
offshore. Upper level disturbance and frontal boundary could bring
some precipitation to our region Sunday into Monday... with some
sub-VFR periods. Drier expected conditions Tuesday.
Raised a Gale Warning for north of North Beach, MD and the upper
tidal Potomac River through tonight per observations. Strongest
gusts over the waters through midnight. Mainly 25 to 30kt tonight
and Friday. SCA rest of the waters and all waters Friday as of
now. SCA slowly diminishes through Friday night.
High pressure builds overhead through Saturday with marginal SCA
risk for the morning with continued west to northwest winds.
Mainly dry conditions on Sunday as high pressure moves offshore.
Upper level disturbance and frontal boundary could bring some
precipitation Sunday into Monday. Dryer conditions expected Tuesday.
Small craft advisory may be needed Sunday and Monday afternoons.
MARINE...Small Craft Advisory from 6 AM Friday to 6 AM EST Saturday for
Gale Warning until 6 AM EST Friday for ANZ530>532-535-538>540.
Small Craft Advisory from 6 AM Friday to midnight EST Friday
night for ANZ530-538.
Small Craft Advisory until midnight EST Friday night for
Small Craft Advisory until 6 AM EST Saturday for ANZ533-534-
Small Craft Advisory from 6 AM to 6 PM EST Friday for ANZ535.