Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 190209

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
909 PM EST Wed Jan 18 2017

High pressure will build toward the region tonight before
settling overhead Thursday. A warm front will move into the area
Friday and stall out nearby through Saturday. Low pressure will
affect the area to start the new week.


High pressure is centered over the Ohio Valley this evening. After
breaking up somewhat, stratocumulus clouds have been re-expanding.
Given sharp inversion shown on 00Z IAD sounding and little
additional cooling expected aloft, these clouds will be slow to
erode and may expand a bit more to the south with the continued
northwest flow. In the near term, the clouds could keep the
temperatures a little higher tonight across the north. Currently,
it appears the clouds should gradually scatter out through
Thursday morning. Elsewhere, low temperatures in the lower to mid
30s look on track.

On Thursday, high pressure moves right overhead. High clouds will
cross at times, though some puffy low cumulus or stratocumulus
may linger in northern portions of the area as well. Temperatures
aloft will remain mild for January so surface temps should rise
back into the 50s in most of the area thanks to rather plentiful
sunshine. Winds will be fairly light under the high.


Warm front starts to lift back north towards us on Thursday night
and enters southern Virginia before stalling out on Friday. Warm
advection surge with the front will result in increasing clouds
Thursday night, with a period of rain looking definite starting
mid-late morning and lasting into early afternoon Friday. That
rain should leave the area late in the afternoon, though lingering
low level moisture and light southeast flow may result in patchy
fog and/or drizzle which could linger through Friday night. Lows
Thursday night will be in the 30s with highs Friday afternoon in
the mid to upper 40s generally. Lows Friday night will drop back
into the lower 40s with plenty of clouds and the potential for


Weak high pressure will be overhead Saturday into Saturday night.
Temperatures will stay mild throughout the period. A separate area
of high pressure over New England could aid in some cloud cover
with an upslope flow. A few rain showers can`t be ruled out,
mainly Saturday night.

A storm system will develop over the Mississippi Valley and
deepen as it pivots northeastward Sunday and Sunday night. This
low could send additional energy into our region Sunday into
Sunday night, bringing rain showers to the region.

On Monday, the main low will move to the northeast a little
further. The threat for showers and perhaps a rumble of thunder
exist Monday into early Monday evening. Temperatures will remain
mild. Drier air will push in behind the departing storm system
Monday overnight.

High pressure will usher in cooler and drier air Tuesday and
Tuesday night. Clouds will break for sun, except for clouds and
upslope rain and/or snow showers in the Potomac Highlands

An upper level trough of low pressure will sag from the Great
Lakes region toward the mid-Atlantic Wednesday. A return of mild
air from the south will evolve ahead of the trough with some
sunshine giving way to some clouds.


High pressure is building in from the west this evening, which
has allowed northwest winds to subside. However stratocumulus is
expanding again to the south under an inversion. MRB has dropped
to MVFR, and it`s possible this could overspread the remaining
terminals (except CHO) overnight. If these cigs do occur, it may
take some time into Thursday morning before they lift/scatter out.

Light winds with limited clouds for the remainder of Thursday.
Cigs redevelop and begin to lower later THursday night with a
period of rain and sub-VFR, if not sub-MVFR conditions looking
likely on Friday. IFR looking possible with lingering clouds,
drizzle and fog behind the system Friday night.

VFR conditions Saturday. MVFR conditions Saturday night with a
chance of a few rain showers, mainly at the CHO terminal. Winds
light and variable Saturday. Winds easterly around 5 knots
Saturday night.


While northwest winds have generally subsided this evening, there
was a resurgence on the Potomac near Dahlgren with a few 18-20 kt
gusts. Have covered these with a Marine Weather Statement, with
expectation that gusts continue to subside as high pressure moves
into the area.

Should be sub-SCA for Thursday with high pressure overhead. Warm
front approaches from south on Friday with rain and mist, but
winds should stay sub-SCA. Drizzle and mist may linger Friday
night, but still sub-SCA winds expected.

No marine hazards Saturday and Saturday night.




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