Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 251443
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
943 AM EST Sun Feb 25 2018

.SYNOPSIS...
A stationary boundary draped across southern Virginia will lift
northward today as a warm front. A cold front will approach from the
west and cross the area by this evening. High pressure will then
build in over the region, migrating off the Mid Atlantic coast by
midweek. A broad area of low pressure will approach the Great Lakes
region on Thursday, bringing unsettled weather to our region through
weeks end.

&&

.NEAR TERM /THROUGH TONIGHT/...
Dense Fog Adv was extended for S MD and adjacent waters until
11am. Main channel of showers moving through the forecast area
today... mainly this morning. Have adjusted the forecast based
on the latest models and trends. Went with a combo of the models
that have been doing best most recently for high temps today,
including NAM, NAMNest, Euro, Hi_Res ARW...those which you
would expect would do best in damming situations. Improving
conditions today.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
High pressure continues to move eastward over the Mid Atlantic on
Monday, with a shortwave trough crossing overhead and pressing off
to our east by Monday evening. This will help skies to finally start
to clear by Monday afternoon, bringing a welcome return of some
sunshine. Did keep slight chance POPs in the gridded forecast for
the first half of Monday for our extreme southern zones as some
guidance wants to keep the frontal boundary just close enough to
have the possibility of light shower activity for these areas.
Temperatures remain above normal on Monday, with highs in the middle
to upper 50s. High pressure will settle overhead Monday night,
coupled with light winds, this allow temperatures a good chance to
radiate under mostly clear skies. Middle to upper 30s will be
prevalent in the metro areas, with lows at or slightly below
freezing along and west of the Blue Ridge. Clear and dry conditions
continue Tuesday and Tuesday night as high pressure dominates the
region, migrating off the Mid Atlantic coast by Tuesday night. Highs
on Tuesday will be in the upper 50s to near 60 degrees, with lows
Tuesday night in the upper 30s to near 40 degrees.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The extended portion of the forecast will start out with high
pressure moving offshore. Warm advection in the return flow will
provide enough lift for scattered showers to arrive during the day
Wednesday. The warm front will approach the forecast area Wednesday
night, and arrive on Thursday as mid level energy runs through
rather fast flow. Therefore, PoPs will spread from central
Virginia across the entire area by Thursday. Temperatures will
be mild for the period.

A deep cyclone will be developing in the Great Lakes/Midwest
Thursday, which will be sending a moisture-rich cold front across
the area Thursday night, with some precip likely lingering into
Friday. Believe that rain will be the dominant type with this
system; cold air will be rushing in Friday PM on gusty northwest
winds after the precip departs. This could provide some upslope snow
showers to the Appalachians Friday night.

High pressure will be building across the area Saturday as the
deepening cyclone continues northeast.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Challenge between fluctuations between all flight categories of
restrictions this morning, but the trend is up for both visby
and cigs today. A cold front will approach the terminals midday,
moving east of the area by around 26/00z. As a result, winds
will veer from the south this morning, to the west southwest
this afternoon, and out of the northwest by this evening. Ahead
and along of the front, winds will gust to around 20 knots
during the day, along with MVFR/IFR conditions as
-SHRA moves over the terminals. VFR conditions return in the
wake of the front this evening, continuing through the first
half of the work week as high pressure builds over the region,
promoting light winds and only mid to high level clouds.

Scattered showers will be near the terminals Wednesday, mainly
to the west. While flight restrictions will be possible,
confidence is low. The chances increase sharply Thursday as a
warm front heads north toward the terminals.

&&

.MARINE...
Areas of dense fog over the adjacent waters to southern Maryland
this morning. Also some wind gusts of 15 to 20 kt with a
leading edge of showers moving through the same area this
morning. SCA conditions expected this afternoon as a warm front
lifts northward in to the area and a cold front approaches from
the west. Have left the upper portion of the Bay out of the SCA
at this time as not expecting the warm front to travel this far
north, thus keeping wind gusts down in these areas. The cold
front will sweep through the waters this afternoon, potentially
accompanied by some gusty showers. High pressure builds over the
waters through the first half of the work week, resulting in
light winds over the waters with no headlines anticipated.

Small Craft Advisories not anticipated Wed or Thu either, due
mainly to poor mixing in vicinity of a warm front and complex
storm system.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Dense Fog Advisory until 11 AM EST this morning for MDZ016>018.
VA...Dense Fog Advisory until 11 AM EST this morning for VAZ057.
WV...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for
     ANZ532>534-536-537-540>543.

&&

$$
SYNOPSIS...BKF
NEAR TERM...STRONG
SHORT TERM...BKF
LONG TERM...HTS
AVIATION...BKF/HTS/CS
MARINE...BKF/HTS/CS



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