Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 140134
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
834 PM EST Sat Jan 13 2018

.SYNOPSIS...
Canadian high pressure will approach from the northwest through
Sunday...causing blustery conditions. High pressure will build
overhead Sunday night and Monday. A low pressure along with its
associated cold front will pass through from the Midwest
Tuesday. Low pressure will continue to develop offshore
Wednesday before high pressure returns for late next week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Blustery northwest winds will continue through tonight as high
pressure slowly approaches from the Midwest. More cold advection
will cause min temps to drop into the single digits and teens
tonight with wind chills ranging from 10 to 15 blow zero along
the ridge tops to the single digits for most other locations. A
Wind Chill Advisory is in effect for the ridge tops.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Canadian high pressure will slowly build overhead Sunday
through Sunday night...bringing dry and cold conditions. Highs
Sunday will remain in the 20s for most locations despite
sunshine. Lows Sunday night will be in the single digits and
teens. Did lean toward the colder guidance Sunday night for
rural areas and sheltered Valleys due to radiational cooling.
There will be some high clouds that could prevent radiational
cooling to some degree...but current feeling is that the deck
will be thin so it shouldn`t have too much of an impact.

High pressure will remain overhead Monday before weakening and
gradually shifting toward the east coast Monday night. More dry
and cold conditions are expected during this time. Max temps
Monday will range from the mid and upper 20s in northern
Maryland to the middle 30s in central Virginia.

A northern stream closed upper-level low and surface low will
drop south into the Great Lakes Monday night. This system will
begin to carve out a longwave upper-level trough over the
central CONUS. High and mid-level clouds will increase during
this time...but it should remain dry with the system still well
to our west.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
The middle of next week will feature cold weather with some
snow chances, followed by a moderating trend during the late
week and into next weekend.

A clipper system will be moving through the Great Lakes on
Tuesday with its trailing cold front crossing the area Tuesday
and Tuesday night. As an upper level trough/energy and jet max
move atop the boundary Tuesday night, cyclogenesis will likely
occur off the eastern US coastline, with the low then moving
northeastward towards the Canadian Maritimes Wednesday/Wednesday
night.

Uncertainty is still high with regards to the evolution, but
there will be chances for some accumulating snow in the Tuesday-
Wednesday time-frame, first with the frontal passage and the
intensifying upper jet, with potential for additional snow if
the low can develop and intensify at a further west longitude
and further south latitude. Climatology and pattern at this
point would favor points further north/east towards New England
for the more significant snowfall.

Cold and blustery conditions will follow behind the front for
later Wednesday and into Thursday with high pressure and
moderating conditions expected for Friday and into the weekend.

Highs ahead of the front Tuesday will be in the 30s/40s,
falling into the 20s for Wednesday, and slowly moderating
through the 40s by Friday and perhaps back near 50F for next
Saturday. The coldest night will be Wednesday night with
widespread teens in the forecast.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR conditions are expected through Monday night. Northwest
winds gusting around 15 to 30 knots this evening will gradually
diminish tonight through Sunday. Light winds are expected
Sunday night through Monday night.

There is potential for sub-VFR conditions in some snow in the
Tuesday-Wednesday time-frame, although uncertainty is high at
this point. Widespread VFR will return for Thursday. Gusty
northwest winds are also expected to develop Wednesday into
Thursday.

&&

.MARINE...
Canadian high pressure will approach the waters through Sunday
before building overhead Sunday night into Monday. The high will
gradually weaken and slide east Monday night. A Small Craft
Advisory remains in effect for the waters for gusty northwest
winds through Sunday. The strongest winds are expected through
this evening with peak gusts around 25 to 30 knots.

Sub-SCA conditions likely to begin Sunday night, although
potential for SCA conditions will return later Tuesday and
Tuesday night, and especially Wednesday into Thursday as a cold
front crosses the region and northwest winds increase behind the
front.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Wind Chill Advisory until 10 AM EST Sunday for MDZ501.
VA...Wind Chill Advisory until 10 AM EST Sunday for VAZ503-504-507-
     508.
WV...Wind Chill Advisory until 10 AM EST Sunday for WVZ501-503-505-
     506.
MARINE...Small Craft Advisory until 5 PM EST Sunday for ANZ530>533-535-
     536-538>542.
     Small Craft Advisory until 11 PM EST Sunday for ANZ534-537-543.

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL/RCM
SHORT TERM...BJL
LONG TERM...MM
AVIATION...BJL/MM/RCM
MARINE...BJL/MM/RCM



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