Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 150256

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1056 PM EDT Sat Oct 14 2017

High pressure over the area will weaken rapidly through
Sunday. A cold front will push into the Mid Atlantic Sunday
night followed by a return to high pressure early next week.



CAD induced low clouds which have hung over the area for the
past 3 days did erode some this afternoon, but not in entirety
as the eastern part of the forecast area did not erode. 11-3.9
mu imagery show these clouds are slowly working their way
back westward. IAD 00Z sounding looked relatively dry, but
believe low level moisture will reassert itself after midnight,
question is will this be in the form of low clouds or fog.
Midnight shift will have a better handle on this.



Southerly flow will increase ahead of a cold front Sunday. Any
low clouds or fog that does form will erode by mid morning.
Advection and insolation will allow temps to rise back above 80

The cold front will pass through the area Sunday night. The
best support will come from low-level convergence and thermal
advection. Showers should result, but am not sold on a solid or
prolonged period of precip, and have back POPs down accordingly.

The pressure surge that follows Monday will bring gusty winds
and cooler temperatures. Some upper 30s possible in outlying
areas by Monday night.


High pressure will promote dry conditions Tuesday through Saturday.
Tuesday`s high temperatures and Tuesday night`s low temperatures
will be about 5 degrees below normal. Wednesday and Thursday will
warm up to near or slightly above normal with plenty of sunshine
each day. Friday and Saturday are expected to be warm with sunshine.
Highs each day in the middle to upper 70s.


With plenty of moisture left in the boundary layer, anticipate
either clouds redeveloping or fog forming after midnight.
Currently, forecast is leaning toward the fog scenario, but
could easily see low clouds instead. Either way, expect IFR (or
lower) after midnight through the morning push.

Mixing will be better tomorrow, so flight restrictions should
dissipate quicker. VFR by mid-morning through the rest of the
day. Some G20kt gusts likely.

Cold front will cross through the terminals Sunday night.
Associated flight restrictions should be fleeting. Best bet
would be for briefly lower cigs.

Monday, perhaps as early as predawn, northwest winds will
increase. That would be the only potential flight restriction,
due to NW flow G20-25 kt. VFR and decreasing winds Monday night.

VFR conditions Tuesday through Wednesday night. Winds light and
variable each period.


Light winds tonight, with increasing south flow on Sunday ahead
of a cold front. Have a Small Craft Advisory in effect for all
waters Sunday afternoon/early evening (started a little earlier
for the Bay/lower Potomac). The threat likely will continue
through Sunday night on the Bay and mouth of the Potomac.
Confidence not as high, but Advisories have been extended

A cold front will cross the waters Sunday night. There may be a
bit of a lull in the mixing during the rain/wind shift. Mixing
will then improve Monday. Although not continuous, Small Craft
conditions likely on Monday as a result.

No marine hazards Tuesday through Wednesday night.


A surge of warm air is expected Sunday ahead of the cold front.
We are not currently forecasting records, but we are expecting
temps to be close.

     Warm Temperature Records for October 15 (Sunday)...
     High             Warm Low
DCA  87 (1975)        67 (2008)
BWI  86 (1989, 1975)  66 (1941)
IAD  88 (1989)        64 (1985)


MARINE...Small Craft Advisory from 10 AM Sunday to 6 AM EDT Monday for
     Small Craft Advisory from noon to 8 PM EDT Sunday for ANZ535-


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