Area Forecast Discussion

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.
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.
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
mid 80s.
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
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 
Monday night.
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.
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 
Sunday night.
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