Area Forecast Discussion
Issued by NWS Sterling, VA
FXUS61 KLWX 250135 AAA
Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
935 PM EDT Mon Apr 24 2017
Low pressure over South Carolina coast will move slowly
northeastward along the North Carolina coast Tuesday evening,
and finally off the Mid-Atlantic Wednesday. A cold front will
approach the region late Thursday or early Friday and remain
nearby through the weekend.
.NEAR TERM /THROUGH TUESDAY/...
Moisture will continue to increase overnight and Tuesday morning
on an ESE fetch with occasional rain expected through the night.
There could be a lull in precip between 09Z-12Z before
additional rain moves in after 12Z.
The coastal low will slowly move northward tonight and the
pressure gradient across the Mid-Atlantic region will tighten.
Expect a steady E-NE wind 10-15mph overnight with slighty higher
winds near the Chesapeake Bay.
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Rain will ramp back up Tuesday morning as the system moves across
the Outer Banks. Rain will continue into Tuesday afternoon with low
stratus and mist around leading to another cool, dreary day. An
additional 0.5 inch of rainfall is expected Tuesday as low pressure
spins to the south. Local enhancements on the eastern slopes of the
Blue Ridge are possible due to easterly flow in the low-levels.
Low pressure will move off the east coast Tuesday night and rain
will end from west to east overnight. Moisture will still lag across
the region leading to low stratus overnight. Dry air and sunshine
will move into the region from west to east Wednesday. It may be
slow to reach the I-95 corridor but sunshine may peak out by late
afternoon across Washington/Baltimore. Ridging moves overhead
Wednesday night and dry conditions are expected. Temps will rebound
into the 70s Wednesday.
.LONG TERM /THURSDAY THROUGH MONDAY/...
Much warmer weather is expected for later this week and through the
weekend, along with the chance for some isolated to scattered
showers and thunderstorms.
Ridging aloft will move overhead on Thursday, while at the same
time, a low pressure system will pull into the Great Lakes. This
will lead to increasing sunshine and warmer southerly flow, with
highs reaching into the 80s.
Late Thursday, Thursday night, and into Friday morning will see the
approach of a trailing weakening front that will end up washing out
and stalling near or north of the region. A few scattered showers
are possible with the front. Lows will be mild, likely holding in
the upper 50s and 60s. Highs on Friday will remain warm, in the 80s.
Moisture/energy will move along the stalled front near or north of
the region over the weekend with chances for some isolated to
scattered showers/thunderstorms, especially north and west closer to
the boundary. Temperatures will be quite summerlike, with widespread
80s, possibly even nearing 90F in a few spots. Overnight lows in the
60s to around 70F.
A strong system is then projected to move into the Great Lakes early
next week with a cold front approaching the region. This will bring
a more widespread chance of showers/thunderstorms.
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Occasional light rain expected through the night with cigs
dropping to IFR overnight and Tue. Improvements expected on Wed.
After the possibility for some lingering reductions Thursday morning
in low stratus/fog, mainly VFR is expected Thursday through Saturday
with the potential for localized reductions in isolated to scattered
Gale warning issued for the lower waters. Occasional gusts to
33kt expected through the rest of this evening with a sig
increase in winds after 06Z. Gale force winds more likely in the
09Z-15Z period. Otherwise, strong SCA conditions through Tue.
SCA will be possible late Thursday and into Friday morning with
increased southwest flow ahead of a weakening frontal system.
Generally sub-SCA winds are then expected Friday and Saturday. Some
isolated to scattered showers and thunderstorms will also be
possible during this time.
Easterly flow around low pressure to the south will foster
persistent onshore flow over the waters through Tuesday...which
will keep tidal anomalies elevated. Onshore flow will continue
to strengthen through Tuesday...with minor flooding possible
near times of high tide. Minor tidal flooding is expected at
Straits Point/St. Mary`s county and a coastal flood advisory is
in effect for the next high tide cycle through late tonight.
There is still uncertainity in flood potential at other
sensitive sites for the next high tide cycle.
Tidal anomalies will increase through Tuesday and there is a better
chance for minor tidal flooding into Tuesday...especially at
the most sensitive sites (Annapolis, Straits, and DC). The flow
should gradually turn north Tuesday night into Wednesday as the
low moves away from the area. Water levels should decrease
during this time.
MD...Coastal Flood Advisory until 4 AM EDT Tuesday for MDZ017.
MARINE...Small Craft Advisory until 4 AM EDT Wednesday for ANZ530>533-
Small Craft Advisory from 11 AM Tuesday to 4 AM EDT Wednesday
Gale Warning until 11 AM EDT Tuesday for ANZ534-537-543.
Small Craft Advisory until 6 PM EDT Tuesday for ANZ535-536.