Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 281858
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
258 PM EDT Tue Mar 28 2017
A cold front will cross the area tonight. High pressure builds
over the region Wednesday into Thursday. Another disturbance
will approach the area late Thursday into early Saturday.
.NEAR TERM /THROUGH TONIGHT/...
Latest surface analysis depicts a stationary front draped near
the Mason-Dixon Line on east, with low pressure over central
Maryland. West of the low, the front continues west into the
upper Ohio Valley, then turns southwest down the valley towards
Missouri. Aloft, a sharp trough is located over the region, with
ridges aloft to the immediate east and west.
Through this evening, both the surface low and upper level
trough will push eastward into the Atlantic. Dry air will slowly
move into the region aloft, so despite relatively moist and warm
low levels, the drying aloft will start to gradually limit storm
development as CAPE dwindles. Shear is pretty low so think there
should be very limited severe threat, but a few strong gusts are
not impossible. With cold temps aloft, small hail will also be a
The surface front will then start dropping south across the
region later this evening and overnight. Low levels will start
to cool and dry out and the showers should completely end after
midnight. Some patchy fog may try to develop in spots where the
wind doesn`t pick up fast enough, but overall, think it should
be minor since clouds will likely linger for a while. Lows will
remain on the mild side, with 40s and 50s common.
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
High pressure builds in from the north on Wednesday with a
breezy north wind. Temperatures will not be as warm and the
humidity will be noticeably lower, but still on the nice side
for late March with 60s common. Winds will relax Wednesday night
as the pressure ridge pushes directly overhead, and with dry air
in place, we may radiate down towards freezing or even a bit
below in the colder spots.
By Thursday, clouds will start to increase as warm advection
begins ahead of the next approaching low pressure. The clouds
should limit the insolation and temps will get stuck in the
50s. Some rain may move into western areas late in the day, but
think for most areas, it will wait until after dark Thursday
night. Low pressure will slide east toward us through the day
Friday, with periods of rain looking likely. There is a good
southerly fetch with this system overruning the cool wedge at
the surface, so potential for some decent rain. Right now, it
appears the wedge will mostly hold with this system, so highs
Friday look to remain in the 50s.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The chance for rain showers linger Saturday before drier and
cooler air can filter into the region Saturday night when high
pressure works its way into the mid-Atlantic.
High pressure will settle into the region Sunday through early
Monday. Dry and seasonable temperatures expected throughout the
The next storm system will move into the region midday Monday
through Tuesday, bringing the chance for rain showers to the
region once again.
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Scattered to numerous showers and isolated to scattered
thunderstorms are expected through the rest of the day into this
evening. Brief reductions in cig and vis, small hail and gusty
winds to 35 knots are possible. Outside of storms, conditions
should be mostly VFR, though some MVFR cigs and vis remain in
spots. Overnight, some lower clouds look to linger until the
cold front moves through, with cigs possibly dropping to IFR
levels for a time. Early Wednesday, the front should sweep away
the low clouds and it should turn VFR until Thursday night, when
the next system will bring more rain and potential for IFR cigs
Mvfr conditions Saturday. Winds northwest 10 knots Saturday.
Vfr conditions evolving Saturday night. Winds northwest 5 knots
Isolated thunderstorms possible into this evening. Winds in any
storm could gust to 35 knots, though odds are low.
An SCA has been issued for tonight and Wednesday behind a cold
front. Northerly winds are expected to gust to 20 kt. Winds
should diminish Wednesday night and remain sub SCA during the
day Thursday with high pressure passing the area.
Potential for Small Craft Advisory conditions increases Thursday
night and Friday with increasing southeasterly winds ahead of an
approaching system. Winds will then turn north/northwesterly on
Saturday behind the system, with continued potential for SCA
MARINE...Small Craft Advisory from midnight tonight to 6 PM EDT
Wednesday for ANZ531>534-537-539>541-543.
Small Craft Advisory from 6 AM to 6 PM EDT Wednesday for