Area Forecast Discussion
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FXUS61 KPBZ 272244
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
644 PM EDT Thu Apr 27 2017

.SYNOPSIS...
Warm weather will be interrupted by evening showers and storms
with a weak front.

&&

.NEAR TERM /THROUGH FRIDAY/...
Minor changes made early this evening to fine tune timing of
showers and storms along with hourly temperature trends.
Some isolated strong storms have been observed but there just
is not enough instability to balance out the shear. Expect any
further thunderstorm development to trend weaker in general as
the evening continues. Previous discussion follows..



The weak cold/occluding front will progress rapidly eastward
and across the Upper Ohio Region this evening. Showers and
storms are expected to intensify/expand in coverage given the
destabilizing boundary layer, especially over areas east of a
Dubois to Parkersburg line where peak heating will drive
temperature toward the mid 80s.

Despite impressive deep layer shear, the area has been limited
to a "marginal" severe risk. This seems appropriate given
instability limitations imposed by sub 60 dewpoints and a plume
of warmer mid level air advecting along the advancing front.

The primary severe threat still looks to be from damaging wind
via short, but isolated bowing segments.

Passage of the front will herald diminished convection as the
evening progresses.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
Dry weather returns Friday with high pressure. Any cooler air
behind today`s front will be quickly ejected to the north as
strong warm air advection takes over.

Eastern ridge will try to build late Friday, but will be shunted
by a series of upper level waves which will ride over the top of
the rising heights. These wave will bring showers and storms
back to the area late Friday night and Saturday. Seeing
discrepancies in models solutions on Saturday with the position
and timing of the shortwaves. Have leaned toward a more
northern track, which complies with slowly rising 500mb heights
on Saturday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A warm, but active pattern is figured for the remainder of the
weekend into early next week as a few shortwaves will cross in
continued moist southwest flow along the front. The associated
trough if forecast to lift out as a closed upper low digs over
the Great Lakes by Monday, pushing a fairly strong front across
the Upper Ohio. Given projections of system strength, the
amount of moisture, and a possibly negative tilt to the upper
trough, strong storms appear possible. Behind this system,
quieter weather and seasonable temperatures are expected into
the middle of next week.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR conditions largely expected outside of any brief MVFR
restrictions associated with scattered thunderstorms along a
cold front crossing this evening. Stronger thunderstorms could
generate strong wind gusts.

Expect VFR conditions to be restored in the wake of the front
along with winds shifting from southerly to westerly rather
abruptly. Tonight, west-northwest flow cloud bring in some MVFR
stratocu, but this looks most favorable for the far northern
ports of DUJ/FKL.

.Outlook...
Occasional restrictions are possible this weekend along a
stalled frontal boundary. Better restriction chances arrive with
a strong cold front Sunday night into Monday.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$


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