Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 170035
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
835 PM EDT Sun Apr 16 2017
A cold front will cross the area Monday morning.
High pressure builds over the area Monday night through early
Wednesday. The next cold front will cross the area Thursday
night. High pressure builds over the area for next weekend.
.NEAR TERM /THROUGH MONDAY/...
A cold front is located over Pennsylvania into the Ohio Valley
this evening. A broken line of showers and thunderstorms have
developed ahead of the boundary. This activity will move into
northern Maryland and the Potomac Highlands late this
evening...but latest mesoanalysis shows less instability across
this area relative to the environment that they are in to the
north. Therefore...this activity is expected to weaken as it
moves into our area. Latest guidance continues to show this
weakening before it moves into the Washington and Baltimore
areas...but did allow for a slight chance of showers.
The cold front will drop south overnight and it will move
through our area Monday...first passing through northern
Maryland in the morning and eventually clearing central Virginia
and southern Maryland in the afternoon. At the same time of the
frontal passage...shortwave energy will pass through our area in
the westerly flow aloft. Radar imagery shows showers that have
developed in response to this energy over Ohio and Kentucky this
evening. Have bumped up pops for Monday morning through the
midday hours as this system moves through. Showers are likely
during this time. Timing remains a bit uncertain...but it looks
like there should be a clearing trend from north to south later
Monday morning into Monday afternoon behind the front. A couple
thunderstorms are also possible...but instability should be
limited due to cloud cover. The best chance for thunderstorms
will be across central Virginia Monday afternoon where it will
take longer for the front to move through.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
High pressure will build overhead Monday night...allowing for
dry and cool conditions. Min temps will range from the 40s
across northern and central Maryland into the Shenandoah
Valley and Potomac Highlands...to the lower 50s in Washington
and Baltimore into central Virginia and southern Maryland.
Nice Tue under high pressure. High moves east with waa regime
developing leading to increased precip chances. GFS and ECMWF
differ on this, but have followed the more reliable Euro and
increased PoPs for Wed. Could be a lull in precip Wed night, but
details remain uncertain.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Low pressure moves from the Great Plains into the Great Lakes
Wednesday into Thursday, as high pressure centered over eastern
Canada moves NE... easterly flow over our region. The low
pressure continues to move east Thursday into Friday pushing a
boundary over or stalling it near our region, bringing southerly
flow, but timing and position of this is still uncertain. This
will allow for an increase in PoPs these days. Drier conditions
build on Saturday with a low pressure approaching from the SW on
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR conditions expected tonight. A shower or thunderstorm cannot
be ruled out across KMRB this evening...but coverage will be
widely scattered. A cold front will pass through the area Monday
from northwest to southeast...and an upper-level disturbance
will pass through during the same time. There is a better
chance for a period of showers Monday morning through the midday
hours before drier air eventually moves in from the north. MVFR
cigs/vsbys are possible during this time. A thunderstorm cannot
be ruled out Monday...especially across KCHO where the cold
front will take longer to pass through. Dry wx expected Mon
night through Tue night.
Showers possible Wed through Fri in waa regime.
Winds will gradually diminish tonight due to the loss of mixing.
Will continue with an SCA for the waters this evening and for the
middle portion of the Bay and lower Tidal Potomac River
overnight...but it will be marginal. Winds will turn to the
north behind a cold front Monday...but gusts should remain below
SCA criteria. Winds will turn onshore and strengthen again Tue
with SCA conditions possible. SCA possible again Thu through
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ530-531-
Small Craft Advisory until 6 AM EDT Monday for ANZ532>534-537-