Area Forecast Discussion


270 
FXUS61 KLWX 251427 AAA
AFDLWX
Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
1027 AM EDT Sat Mar 25 2017
.SYNOPSIS...
High pressure over the western Atlantic will be in control
today. A back door cold front will drop southwestward into the
area later tonight and Sunday. The front will lift back to the
north on Monday. Another cold front will drop back south across
the region later Tuesday or Tuesday night. The front will 
stall to the south of our area through the rest of the week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Plenty of cirrus this morning especially across the northern
half. Clouds will thicken and lower during the afternoon as
moisture continues to advect from the west southwest. Chance of
showers increase during the afternoon as frontal zone across
Pennsylvania pushes south. Lowered PoPs for the afternoon across
the north and removed PoPs for remainder of this morning. Temps
already in the mid 60s headed well into the 70s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Confidence in a backdoor front and subsequent onshore flow/cold
air damming has increased, so temperatures were lowered below 
guidance consensus particularly around Baltimore where low 50s 
are currently expected. Also, patchy drizzle was added to the 
Sunday forecast generally Blue Ridge and east. A sharp gradient 
between warm southerly flow and cool easterly flow is expected 
over southern portions of the CWA. Subsequent shifts will need 
to focus on this for the MaxT forecast.
Guidance shifts the CAD wedge north Sunday night. However, it 
is wise to hold onto an onshore flow and lower temperatures 
longer than guidance, so gradual improvement is given for 
Monday.
Low pressure currently over Oklahoma will continue to drift 
northeast reaching the the Midwest tonight before dissipating 
over the Great Lakes under a northern stream ridge Sunday night.
A second low currently along the California coast will reach 
the Midwest Monday night before reaching the eastern Great Lakes
Tuesday (and also dissipating) per 00Z ECMWF/GFS. Continued 
moist southwesterly flow warrants high chance PoPs with slight 
chance for thunder for the LWX CWA Monday. Possibly a break in 
action, so Monday night was kept low at this time.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Guidance is not in great agreement regarding the weather systems
in our region through the long term. However, most models agree
that we will start out in the warm sector on Tuesday. Tuesday
morning, the GFS has low pressure near Lake Erie, while the EC
has the low further southwest over southern Indiana. GFS sends
the low east across the St. Lawrence Valley and brings a cold 
front south in the evening, while the EC solution is slower and
weaker with the low, with any frontal passage delayed until at
least early Wednesday. This system will bring a threat of
showers and thunderstorms with, with notable instablity progged
across our region in the warm sector. By late Wednesday, both 
models have the front south of, with high pressure from Canada
pushing cooler and drier air into the region. The remainder of 
the week appears to be in the cool sector north of the front.
While Thursday starts out dry, by day's end models bring another
low pressure wave eastward into the region, with an increasing
risk of rain by Thursday night and Friday. This system appears
less likely to bring any thunder with it as current guidance
generally keeps the warm sector away from us, resulting in a
cool and rainy end of March.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
VFR under high pressure and southerly flow through today. 
Backdoor cold front shifts west across the DC metros tonight 
with onshore flow 10 to 15 knots through Sunday. Drizzle and IFR
conds eventually develop and spread east to west late tonight 
through Sunday.
Southwesterly flow from low pressure to the west/north Monday 
brings rain showers to the DC metros Monday.
Thunderstorms are the main concern Tuesday. This concern will
end at night and Wednesday looks VFR with some gusty NW winds
likely behind a cold front.
&&
.MARINE...
Southerly flow 10 to 15 knots today interrupted by a backdoor 
cold front tonight. Onshore flow expected Sunday into Monday 
before shifting south.
Generally sub-SCA SWly flow prevails Monday.
Thunderstorms are possible Tuesday. SCA possible behind a cold 
front Wednesday.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 11 PM this evening to 9 PM EDT 
     Sunday for ANZ530>532-538>540.
&&
$$
SYNOPSIS...RCM
NEAR TERM...LFR
SHORT TERM...BAJ
LONG TERM...RCM
AVIATION...BAJ/RCM
MARINE...BAJ/RCM