Area Forecast Discussion
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FXUS61 KLWX 301400
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1000 AM EDT Thu Jun 30 2016
High pressure will move offshore today. A warm front across the
Carolinas will lift north tonight into Friday. A cold front will
move into the region Friday night. High pressure will return to
the Great Lakes and northeast for the weekend. A frontal boundary
is expected to hover over the Mid Atlantic Sunday night and
.NEAR TERM /THROUGH TONIGHT/...
High pressure will move off to the east today and a southerly
flow will develop...ushering more moisture into the area.
Increased dewpoints will lead to more instability...and a pressure
trough along with terrain circulation will act as lifting
mechanisms to trigger scattered showers and thunderstorms this
afternoon. The best chance for convection will be along the
terrain into central Virginia where moisture will be highest.
Having that been said...instability should remain somewhat limited
with the deeper moisture remaining off to our south. This will
minimize the threat for severe thunderstorms. Farther north and
east across the Washington and Baltimore Metropolitan areas into
northern Maryland...northern Virginia and the eastern West
Virginia Panhandle most of the day will be dry. Any convection
will be isolated and confined mainly to the late afternoon hours.
Moisture advection will continue this evening. A few more
showers and thunderstorms are possible during this time...but
coverage should remain isolated to widely scattered. Will attempt
to preserve a diurnal component as CAPE only a couple hundred
joules; thus just have a few showers after midnight and a dry pre-
dawn period. Clouds should be plentiful, but the increased
humidity also makes fog a possibility by early Friday morning.
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Friday`s forecast will be a little bit complicated. There will be
the isentropic ridge in the eastern (metro) part of the forecast
area. Meanwhile, a shortwave and surface cold front will be
crossing the northeastern US. Both features would be capable of
supporting convection given daytime heating. The former will be
pushing east ahead of the front, primarily affecting the Eastern
Shore/Delmarva; while the latter doesnt arrive until Friday night.
Area may end up in between the two, but wish to broaden the range
in forecast grids to account for uncertainty. Highest PoPs will be
in the east. Will introduce chances in the west for the afternoon
and early evening. While shear will be present, the other factors
either aren`t aligning well or are poorly timed. Thus, will be
forecasting scattered, non-severe convection. Will need to monitor
the strength of the shortwave/surface convergence though-- the
setup is quite similar to Tuesday.
The cold front forecast to push through Friday night. (How often
can one say that that for successive cold fronts in the Mid
Atlantic in early July?) Given support of numerous model runs, am
fairly confident that this will lead to a partly-mostly sunny
Saturday...even though this solution is a departure from
climatology. The only wrinkle may be the extent of high level
clouds, as the jet stream will be overhead.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Zonal flow aloft is expected Sunday as a stationary front is located
across the southern Mid-Atlantic region. The front will waver into
Monday and showers will be possible in vicinity of the front...
mainly across central VA and southern MD. The front is expected to
retreat northward as a warm front into Tuesday. Showers may increase
in coverage Monday night into Tuesday night. A shortwave trough may
impact the region Wednesday and Thursday. Temps should stay below
normal Sunday-Monday and near normal Tuesday-Wednesday.
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
VFR flight conditions should generally prevail today.
A warm front will approach the terminals late today and tonight.
With it, thunderstorm chances increase. Scattered areal coverage
preclude TAF mention at this time. However, the increase humidity
may yield areas of fog. Will only be forecasting local predawn
MVFR Friday morning, due in part to anticipated cloud cover. There
is the potential for it to be worse.
A cold front will approach the terminals on Friday, and cross
Friday night. Scattered thunderstorms will be possible, especially
during the afternoon and evening hours. Local IFR would be
possible within any thunderstorms, but their coverage in doubt at
High pressure/VFR returns for Saturday. VFR conditions expected
The flow will turn toward the south and southeast today into
tonight...but wind speeds will remain below SCA criteria. The
gradient will tighten on Friday as a cold front approaches.
However, do not have much confidence in any strong winds outside
There are a couple of possible period of storms... tonight as
humidity returns, and Friday ahead of the cold front. The storms
on Friday likely will be stronger, and may be capable of producing
storms requiring Special Marine Warnings.
The cold front will clear the waters Friday night, with high
pressure returning Saturday. If mixing is strong enough, there may
be a window of opportunity for Small Craft Advisory gusts behind
the front Friday night-Saturday morning.
Sub-SCA expected on the waters Sunday-Monday.