Area Forecast Discussion
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FXUS61 KLWX 271431
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1031 AM EDT Mon Mar 27 2017
A warm front will positioned over southern Virginia will
track north through the Mid Atlantic through the afternoon. A
cold front will cross the area late Tuesday. High pressure will
build over the region Thursday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Dense Fog Advisory no longer in effect...as visiblities have
been rapidly improving over the past half hour. Though, marine
stratus layer with low ceilings will remain until warm front
lifts through the area over the next several hours.
As is often the case, guidance is struggling somewhat with the
temporal evolution of the northward moving warm front and
removes the CAD wedge along and east of the Blue Ridge a bit too
quickly. Thus, low ceilings may remain in portions of the area
through mid-afternoon (especially across N MD). Currently don`t
think this will impact todays highs too much...as expecting a
rapid warmup once front lifts through the area (highs M70s).
CAPE gradient sets up this afternoon roughly from Montgomery
County to the south...with ~500 J/kg of MUCAPE (250 J/kg ML
CAPE) expected across central/northern VA into south central
MD. Thus, could be a few scattered thunderstorms this afternoon
with the differential heating boundary across these areas. 0-6
shear generally near 30-35 kts suggests a storm could briefly
become somewhat organized. Though, lack of deep quality
moisture coupled with long skinny CAPE profiles and relatively
weak winds aloft likely limit any stronger thunderstorms. Gusty
winds and small sub-severe hail the primary threats in any
activity this afternoon. Thunderstorm chances rapidly decline
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
While we will be forecasting "chance of showers" overnight
believe for the most part the nighttime hours will be dry. If it
does the best chances will probably be late ahead of the
approaching short wave. Lows generally in the mid 50s.
Tuesday could see thunderstorm activity as the shortwave tracks
through the Mid Atlantic. SPC has placed much of the forecast
area east of the mountains in a marginal risk of severe storms.
Neither the CAPE or helicity look particularly impressive for
Chances for precipitation should be ending Tuesday evening as
the shortwave moves off the coast. High pressure will return
overnight and for Wednesday. Back on the roller coaster...
temperatures Wednesday should be almost ten degrees cooler than
the previous two days.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
High pressure will be building into the Northeastern United States
Wednesday night, sliding east on Thursday. This will lead to drier
and cooler weather, although still near climatological normals. Good
radiational cooling night Wednesday night will lead to widespread
lows in the 30s, with highs rebounding back through the 50s on
Meanwhile, a strong closed low will be moving northeastward out of
the southern plains on Thursday, into the Mid-Mississippi Valley
Thursday night, and towards the Mid Atlantic states by later Friday,
becoming vertically stacked and gradually weakening. Model guidance
is in relatively good agreement with this progression and timing. As
the system makes its way to the eastern seaboard, some redevelopment
off of the Mid-Atlantic coastline Friday night into Saturday morning
is also projected.
Therefore, chances for rain showers increase Thursday night into
Friday morning with initial warm air advection, followed by bulk of
the rainfall likely coming Friday and Friday night with main frontal
push and any subsequent redevelopment. A drying trend should develop
on Saturday, with the chance for some lingering showers as the low
pulls away. High pressure will then build in for Sunday.
Temperatures in the Thursday night - Sunday time period will be
relatively seasonal, skewing slightly above normal. Lows will be
mainly in the 40s. Highs coolest on Friday in the 50s with
clouds/showers, rising into the 60s for the weekend.
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
Slow improvement expected over the next few hours as ceilings
slowly rise. Conditions are expected to reach VFR this
afternoon. Scattered thunderstorms are possible this afternoon. There
will be chances of rain showers late tonight at all TAF
sites..and then possible thunderstorms Tuesday afternoon. DCA
has the best chance for strong gusty winds.
VFR Tuesday night and Wednesday.
VFR expected Wednesday night and Thursday, but chances for sub-VFR
conditions increase Thursday night and Friday with rain and low
clouds as next system moves into the area. Winds light Wednesday
night into Thursday will increase out of the southeast later
Thursday and Friday.
SCA currently in effect for the southern portion of the waters.
An isolated thunderstorm with gusty winds is possible this
afternoon into the early evening across the waters.
Thunderstorms will be possible Tuesday afternoon, some of which
could produce SMW level winds. This will need to be monitored.
Sub-SCA conditions expected Wednesday night and Thursday. Potential
for SCA then increases Thursday night and Friday with increasing
southeasterly winds ahead of an approaching system.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ533-