Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 131955

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
255 PM EST Tue Feb 13 2018

High pressure will move offshore tonight into Wednesday. A warm
front will then cross the region during midweek, followed by a
cold front late in the week. Another wave of low pressure may
affect the area over the weekend.


Moisture and warm air advection is ongoing this afternoon, and
with that, clouds have enveloped much of the area, and will be
region-wide by late this afternoon. In addition, there are some
scattered sprinkles and light rain showers, and perhaps even a
few sleet pellets out there, and these will continue pushing
across the region. Dry air at the surface due to surface ridging
will prevent anything other than a few light showers from

Clouds persist tonight, although there may be some breaks of
clearing. Most areas will remain dry, but with strengthening
westerly flow and another surge of moisture and warm air
advection towards morning, some light precipitation is possible
along and west of the Allegheny Front. Temperatures will cool
initially, with lows from 28-35F, but will warm towards morning
west of the Blue Ridge, so while there is a slight chance of
some patches of light freezing rain, coverage will be limited,
if any at all.


Southerly flow will increase across the region on Wednesday, and
with it will come warming temperatures. Most locations are
expected to remain dry, but as a surface low passes well north
of the region, dragging a warm front near the area, and a weak
disturbance moves towards the region, showers become more likely
along and west of the Allegheny Front during the day, and
possibly as far east as the Blue Ridge by the evening. Highs
should reach into the 50s area- wide, possibly near 60F across
portions of central/western Virginia.

More widespread showers will then push eastward and across the
remainder of the region Wednesday night. Temperatures will be
quite mild, with lows in the 40s to around 50F, so no mixed
precipitation issues are expected.

Southwest flow and warm conditions will be the story for
Thursday on the warm side of the boundary. High temperatures
from the mid 60s to low 70s are likely. A cold frontal system
will then begin its approach from the northwest late in the day,
and some showers become more likely by the afternoon north/west
over western Maryland and eastern West Virginia.

The cold front will continue its approach and be on the doorstep
by Friday morning. Rain will become increasingly widespread
Thursday night from northwest to southeast, although downsloping
on strong westerly flow will initially limit coverage/intensity.
A very mild night is expected with lows only in the 50s.


A cold front will be moving through our region on Friday which
will bring rain over our CWA. High temperatures will be above
normal, reaching the 50s and 60s. Conditions should be drying
out in the evening and will continue into the overnight hours
with near normal temperatures and breezy conditions.

The front will stall south of us and a wave of low pressure will
move through it. Some guidance keep the front close enough where we
could get additional precipitation on Saturday. Latest GFS keeps our
CWA dry through Monday as high pressure builds in, while most GEFS,
Euro and the Canadian support a wetter solution for Saturday and
into Sunday, maybe Monday. Temperatures will be marginal in the
overnight hours, so cannot rule out snow at this moment.

Guidance suggests that another frontal system could bring unsettled
weather for early next week.


VFR is expected through at least Wednesday with mainly dry
conditions and BKN-OVC variable VFR cloud decks. A few light
rain showers or sprinkles are possible.

Sub-VFR potential becomes higher Wednesday night as a
disturbance moving through bringing some showers. Conditions
will then improve on Thursday, accompanied by southwest wind
gusting 20-30 knots. Sub-VFR conditions become possible once
again Thursday night as showers move across the region ahead of
a cold front.

Sub-VFR conditions possible over the terminals on Friday as
front moves through our region. Conditions could improve on
Friday night to VFR but is uncertain how close will this front
stall into the weekend, therefore sub-VFR/unsettled weather is
possible during this time. Gusts up to 20 kts on Friday.


Sub-SCA conditions expected through Wednesday as high pressure
gradually slides eastward and winds remain relatively light. By
Wednesday night, southerly flow will be on the increase and SCA
conditions become possible across portions of the waters from
Wednesday night through Thursday night.

SCA conditions expected Friday into Friday night as
front moves through the region. Winds will be decreasing on Saturday
and remain below SCA criteria into Sunday.


Unseasonably warm weather is expected on Thursday. While temps
will be over 20 degrees above normal, it will be difficult to
top the record highs in Baltimore and Washington. However, the
record highs at Dulles could be smashed. Below are the current
record highs for Thursday February 15:

DCA   77 in 1949  52 in 1909
BWI   77 in 1949  51 in 1949
IAD   68 in 1982  44 in 1984 and 1967




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