Area Forecast Discussion
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FXUS61 KLWX 261835
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
235 PM EDT Wed Apr 26 2017
Low pressure east of New Jersey will slowly move away from the
coast. A cold front will approach the region and weaken over the
area Thursday night. A backdoor front may slide into the area
late Saturday into Sunday. A cold front will pass through the
region early next week.
.NEAR TERM /TONIGHT/...
The atmosphere over the Mid Atlantic is moving in slow motion
courtesy of a vertically stacked low east of NJ. As discussed
this morning clouds across northern VA/MD/DC have barely
changed height/thickness today. This is trudging slowly to the
northeast...and clouds should be thinning tonight in the
northeast part of the forecast area...while skies should be
clear in the central Shenandoah Valley from early evening on.
The clearing skies should lead to good radiational conditions
which in turn will lead to fog formation late tonight.
Lows in the 50s except lower 60s in the cities.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
After the low pressure area finally departs and moves east of
Cape Cod Thursday skies should finally return to a mostly sunny
condition - after some early morning fog. Highs in the lower to
But the respite from clouds will be short. A cold front will be
pushing into the Mid Atlantic Thursday night bringing the
chance of showers/isolated thunderstorms. This will not be
coming through at a prime time for severe weather. Coverage will
be spotty, so one place could pick up a few tenths of an inch of
rain while ten miles away stays dry.
The front is expected to be east of the region by Friday
morning. Skies should improve, highs again in the lower to mid
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
High pressure will be to our southeast with a front along the Mason-
Dixon line Saturday and Saturday night. Temperatures will remain
warm with a chance of showers or a thunderstorm mainly across the
northern half of our region.
By Sunday into Sunday night, the high to the southeast will break
down with the front sliding across the D.C. area during the day
before meandering northward as a warm front Sunday night. The chance
for showers and thunderstorms will become more prominant, mainly
Sunday with the front nearby and before the warm surge.
An increasing southerly wind will usher in warmer and more humid air
to help fuel showers and thunderstorms Monday into Monday evening. A
strong cold front should works its way eastward across the region
Gusty westerly winds and drier and cooler air will filter into the
region Tuesday and Tuesday night behind the cold front as high
pressure builds in from the west.
High pressure moves offshore Wednesday, while keeping conditions
dry. A return flow will be an indication that a new warm front will
try to push across the region later Wednesday.
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
With the exception of CHO all ceilings at airports in our area
remain at MVFR levels. Improvement should continue into the
evening hours, at which time all sites should return to VFR. Fog
development is possible overnight. For now have taken all sites
down to 2-3 miles around 09Z-13Z. Later shifts can adjust
up/down depending upon latest guidance/obs.
VFR after about 13Z Thursday. Showers/isolated thunderstorms
possible Thursday night as a cold front moves through. VFR again
Mvfr to ifr conditions expected Saturday through Sunday with showers
and thunderstorms in the area near MRB, IAD, MTN and BWI terminals.
Vfr conditions elsewhere. Mvfr to perhaps vfr conditions Sunday
night. Winds southwest around 5 knots Saturday, becoming light and
variable Saturday night, then east 5 to 10 knots Sunday, and
southerly 5 to 10 knots Sunday night.
Winds expected to remain below SCA values through tonight. On a
more southerly flow Thursday will keep winds capped at 15 knots.
Showers/isolated thunderstorms will be possible Thursday night.
No marine hazards expected Saturday through Sunday night. Winds
southwest 5 to 10 knots Saturday, becoming light and variable
Saturday night, then east 10 knots Sunday, and southeast 10 knots
Water levels have decreased slightly with northwest winds today but
remain elevated, especially from the Potomac River southward.
Straits Point will be near if not exceeding minor flood stage for
the next two high tide cycles. Guidance shows steady to decreasing
waters for the remainder of the week, but am a bit skeptical about
this outcome considering winds will become south or southwesterly
through that time. Thus minor flooding at sensitive sites will need
to continue to be monitored. In terms of the current guidance,
Friday morning will be the next targeted opportunity.
MD...Coastal Flood Advisory from 1 AM to 6 AM EDT Thursday for