Area Forecast Discussion
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FXUS61 KLWX 190800
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Sun Mar 19 2017
.SYNOPSIS...High pressure will build over the area today and
tonight, before a cold front crosses the area Monday night.
Strong high pressure then builds across the region during the
middle to latter part of the week.
.NEAR TERM /THROUGH TONIGHT/...Light snow has been falling
across Frederick and Carroll counties in MD since about 11PM
with rain elsewhere except in the Shenandoah valley where it has
remained dry. Over the next few hours, we`ll see rain/snow line
shift southward as column continues to cool down beneath upper
low. No snow accumulation expected outside Carroll and Frederick
counties where an inch or two are possible mainly on grassy
surfaces. Upper low and trof axis will shift east later today
with precip ending by 15Z if not sooner.
High pressure then builds overhead tonight with clearing
expected by daybreak Monday. Chilly with temps in the low 30s
east and upper 20s west.
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...High pressure will
then shift rapidly to the south with showers expected in the
afternoon and night as cdfnt crosses the area. Low pressure
developing along front across North Carolina Tue night will
bring another round of rain Tue evening with rain ending by
daybreak Wed. Some accumulating snow is likely across the higher
elevs of eastern WV and Highland county.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Computer model guidance
is in good agreement through Friday. By Wednesday morning, the
precipitation should be over as the area of low pressure moves
offshore. A secondary, but dry, front will push southward during
the day as an upper level trough axis swings through the
northeastern states. Colder air will rush into the area with
below normal temperatures expected.
Surface high pressure will build over the central Appalachians by
12Z Thursday, and favorable radiational cooling will result in
lower 20s in outlying areas. Temperatures will moderate slightly for
Thursday. The surface high will move offshore Friday while upper
level ridging builds overhead. There will be some additional cloud
cover due to warm advection aloft, but it will likely stay dry with
Guidance spread begins to increase Saturday as a low pressure center
moves into the Great Lakes and drags a cold front toward the area. A
faster solution (such as the GFS) would result in showers for
Saturday. Unless the front moves through early in the day though,
high temperatures could push 70F.
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...IFR conditions through
13Z with rain changing to snow after 09Z and ending by 13Z. Cigs
improve to MVFR after 13Z and become VFR by 18Z. Next chance of
rain is Mon afternoon and night with next frontal passage.
VFR conditions expected Wednesday and Thursday as high pressure
builds into the area. NW winds could gust to 25 kt Wednesday, with
lighter winds by Thursday.
.MARINE...Solid SCA conditions today, then winds begin to
diminish this evening. Possible SCA again Tue night.
Secondary cold front passage on Thursday will result in gusty NW
winds with SCA conditions possible. Winds will diminish heading
into Thursday as high pressure builds overhead.
MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ530-
Small Craft Advisory until 6 AM EDT Monday for ANZ532>534-537-