Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 klwx 181418 
afdlwx

Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1018 am EDT Mon Mar 18 2019

Synopsis...
weak low pressure will pass through the area today and high
pressure will return for tonight through Wednesday. A cold front
will pass through the area Thursday and high pressure will
return for Friday into the weekend.

&&

Near term /through tonight/...
weak low pressure will pass through the area this morning. Most
of the lift will be provided by a potent jetmax and digging
upper-level trough. However, moisture is limited and much of
the radar returns are not reaching the ground due to dry air
aloft as seen in the 12z sounding. Having said that, a period
of light rain/snow and mountain snow is possible with the
passage of the low through the morning. The best chance for
light precipitation will be across the Potomac Highlands of West
Virginia into northern Virginia and toward the Washington and
Baltimore metropolitan areas. There is enough cold air aloft
that if precipitation does occur there could be some snow even
into the Metro areas. However, precipitation rates would be
light (if anything at all) due to the abundant amount of dry air
in place, and with relatively warm conditions preceding this
event, this suggests that chances for accumulating snow in the
Metro areas are low. There is a better chance for snow to coat
the ground in the mountains.

As the trough digs, an upper-level disturbance will pass through
the area late this morning through this afternoon. This may
trigger a few more showers, but coverage should be isolated to
scattered for most areas due to weak forcing and limited
moisture. Max temps will range from the 30s and 40s in the
mountains to the 40s and 50s for most other locations. There
should be some breaks of sunshine, but a bkn cu deck is expected
underneath the subsidence inversion as the upper-level
disturbance swings through the area.

High pressure will return behind the departing upper-level
disturbance tonight, bringing dry and chilly conditions. Min
temps will be in the 20s for most areas with 30s in downtown
Washington and Baltimore. Light winds and mainly clear skies
overnight will provide a good setup for radiational cooling in
valleys and rural areas.

&&

Short term /Tuesday through Wednesday night/...
high pressure will build overhead for Tuesday through Tuesday
night before building to our south Wednesday into Wednesday
night. A cold front will approach from the Ohio Valley and
Pennsylvania Wednesday night.

For Tuesday through Tuesday night, dry and chilly conditions are
expected with high pressure in control. Temps will be a little
below climo. Wednesday will also turn out dry, but a return flow
will allow for milder conditions during the afternoon.

A few showers are possible Wednesday night ahead of the
approaching cold front. Precipitation amounts should be light
since moisture will be limited. In fact, the deep moisture
sources of the Atlantic and Gulf of Mexico should not come into
play with this system.

&&

Long term /Thursday through Sunday/...
a cold front will push across the region Thursday and bring a
chance for rain and snow showers. Most of any activity would be
mainly at the higher elevations due to an upslope flow. We
can't rule out a few sprinkles or flurries to the eastern zones,
but moisture may be limited. Temperatures will be near average.

High pressure will build into the region Thursday night through
Sunday. There could be a weak secondary cold front push through the
region late Friday, but it could be moisture-starved and just bring
a reinforcing shot of cooler air Friday night and Saturday.
Temperatures overall will be near normal Thursday night and Friday,
but then a few degrees below normal Friday and Saturday. Milder air
will evolve late Saturday through Monday due to high pressure.

&&

Aviation /14z Monday through Friday/...
VFR conditions are expected most of the time through Wednesday.
A brief period of light rain or snow is possible this morning,
and a couple showers are possible this afternoon. However, much
of the time will turn out dry. High pressure will control the
weather pattern tonight through Wednesday. A few showers are
possible Wednesday night ahead of an approaching cold front.
MVFR conditions cannot be ruled out, but VFR conditions are more
likely since moisture will be limited.

Despite a few passing showers near mrb Thursday, terminals should
encounter VFR conditions Thursday through Friday night. Winds
southeast becoming northwest around 5 knots Thursday and Thursday
night. Winds increasing northwest 10 to 15 knots with gusts to 20
knots Friday and Friday night.

&&

Marine...
weak low pressure will pass through the waters today and high
pressure will return for tonight through Tuesday night. The high
will move offshore Wednesday and a cold front will approach from
the north and west Wednesday night.

Winds through Tuesday night should remain below Small Craft Advisory criteria for
most of the time. However, it may be close for a period ahead of
the building high tonight over the open waters. Confidence is
too low for an advisory at this time.

A return flow will develop Wednesday and it should strengthen
Wednesday night ahead of the approaching cold front. A Small
Craft Advisory may be needed for portions of the waters later
Wednesday and Wednesday night.

High pressure will build toward the waters late in the week. A
Small Craft Advisory may be needed for portions of the waters
during this time.

&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...none.

&&

$$
Synopsis...bjl

National Weather Service Glossary of Abbreviations