Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 180201
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
901 PM EST Fri Feb 17 2017

.SYNOPSIS...
High pressure will linger over the area through Saturday. A
weakening low crosses the area Saturday night. A backdoor cold
front will enter the area Monday into Tuesday, followed by
another disturbance Tuesday night into Wednesday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 9pm, a 1001mb low is over Lubbock and a 981mb low is on
the NW side of Newfoundland. A weak surface ridge is in between.
Just scattered cirrus with light flow and decoupled locations.
Air mass above the surface will be warming rapidly overnight,
but with mainly clear skies and light winds, radiational cooling
should still allow surface/2-meter temperatures to fall into
the 30s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Significantly warmer weather is expected for the weekend. Mostly
sunny skies for the first half of Saturday will give way to
increasing clouds in the afternoon ahead of a weakening
disturbance moving into the southeastern US. Temperatures will
soar to 20-25 degrees above normal, with highs well into the
60s with low 70s south of DC.

The disturbance will pass south of the region Saturday night.
There may be some light rain showers overnight as the system
passes nearby, but any precipitation will be very light. Lows
generally in the 40s.

Dry weather and mostly sunny skies return for Sunday with
another day of highs in the 60s to around 70F. A system will
pass through New England Sunday night, and while not directly
affecting our region, it may set up a backdoor cold front that
will be near the area for Monday. Lows Sunday night around 40F.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Main concern in the long term to start out is the growing potential
for a northeasterly flow behind a backdoor cold front Monday and
Tuesday, and potentially Wednesday as well. This will be due to a
high pressure centered over southeastern Canada allowing cooler
maritime air to surge south and west around the bottom of the high
into our region. While no precipitation is expected Monday and
Tuesday thanks to ridging aloft, low clouds are possible, especially
Tuesday, and temperatures will be cooler than what otherwise might
be expected given warm air present aloft and a ridge overhead.

Wednesday a weakening cold front is expected to move in from the
west. Some showers are possible but significant precipitation is not
anticipated, so our very dry February will continue with little
improvement. As this front moves through, the wedge of cooler air
may be displaced briefly, but may return quickly as high pressure
returns to its favorable location for wedging - southeastern Canada.
Otherwise, late week looks dry.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions prevail through Saturday under high pressure.
Weakening low moves across the area Saturday night...with a
chance for light rain showers. Light rainfall rates should keep
flight restrictions rather marginal/brief...with perhaps a
brief period of MVFR. VFR returns after daybreak Sunday.

Sub-VFR will be possible early next week, especially BWI/MTN, as a
back door cold front could bring some low clouds into the region.
Best chance of this is Tuesday. A little drizzle is even possible
though significant rain is not expected through Tuesday. A few
showers are expected on Wednesday as a weak front passes with
continued chance for sub-VFR. Winds through the period look mostly
below 20 knots.

&&

.MARINE...
Light south flow with high pressure centered to the south. Sub-
SCA winds expected through Sunday night...with the typical
increases/decreases during the day/night due to diurnal mixing
trends.

Backdoor cold front may bring a risk of marginal SCA conditions
Monday and Tuesday with another cold front bringing the same
small risk on Wednesday. Winds may briefly reach 20 knots in
gusts Monday through Wednesday, but should not get stronger than
that.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

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



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