Area Forecast Discussion
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FXUS61 KPBZ 262214
Area Forecast Discussion
National Weather Service Pittsburgh PA
614 PM EDT SUN JUN 26 2016
Above-normal temperatures will continue through tonight. A frontal
boundary will increase chances for showers and thunderstorms later
tonight and Monday, with cooler temperatures expected by the
middle of the week.
.NEAR TERM /THROUGH MONDAY NIGHT/...
-- Changed Discussion --Strong afternoon mixing has actually entrained a bit of drier air
from aloft with subsidence and high pressure in control late this
afternoon. This has allowed for temperatures to surge into the 90s
virtually everywhere while secondarily allowing for cumulus to
fade rapidly beyond peak heating.
A very strong cap is noted on RAP soundings over eastern Ohio at
this time, and any convection that has tried to wander eastward
from western Ohio has hit this cap and summarily died. As such,
pops were removed fully from the remainder of the evening
A frontal boundary is evident from near St. Louis toward Detroit
at this hour with a notable wind shift along it. Convective
activity along it has been anything but remarkable however as
layer saturation and baroclinicity along the front is fairly
paltry. As the front bears toward the area by Monday morning,
scattered showers will become more common, however lacking a
strong signal from any particular model solution resembling deep
saturation along the front, it is not a really convincing signal
for widespread rainfall. As the front sags toward the southeastern
CWA by afternoon, however, diurnal instability will work to allow
for showers and thunderstorms to again bloom along the front.
Drier air moves in rapidly behind the front. This should allow for
areas to really scatter out strongly post frontal passage.
However, a lack of cold advection and strong mixing with lower
dewpoints behind it will likely lead to yet another well above
normal day with temperatures pushing 90F in Ohio and likely the
upper 80s as far east as Pittsburgh. Fries
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.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Showers and storms will wane quickly Monday night in the ridges
as the initiating boundary and most of the low-level moisture
shift southeastward. Except for a brief window late Tuesday
afternoon when a shortwave trough crosses the region, the period
through Wednesday night should remain dry. Tuesday even will see
only limited precipitation owing to the decreasing moisture
Amid broad upper troughing, maxima this period should remain
capped in the mid-upper 70s. As dry air invades on deep
northwesterly flow and sfc high pressure builds, overnight
temperatures will be able to drop more substantially on Tuesday
and Wednesday nights than earlier in the week. Thus, minima in
the 50s as indicated in numerical guidance seem very reasonable.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Southwesterly flow aloft resumes on Thursday ahead of an
amplifying wave in south-central Canada. This flow pattern will
support a slow increase in temperature and moisture late in the
week, as indicated in latest numerical guidance.
Limited moisture transport ahead of the approaching wave could
support modest showers and storms on Friday as the associated cold
front approaches and stalls in the vicinity of the PA/MD/WV border.
PoPs were increased Friday in all areas, and Saturday in the
southern zones, to reflect this scenario, which is depicted in
both GFS and ECMWF forecasts.
High pressure is expected to build into the region next weekend
in the wake of this system. The building high and departing wave
should lead to a southward shift in the frontal boundary and
decreasing chances for precipitation.
.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
VFR conditions into the first half of tonight. A shortwave and
cold front will bring showers after 09Z Monday toward KZZV, and
spreading east Monday morning. Only limited restrictions in any
thunderstorm as the front passes. Behind the front Monday
afternoon widespread vfr will quickly move southeast.
.OUTLOOK /monday NIGHT THROUGH FRIDAY/...
Isolated to scattered showers/storms are possible on Tuesday...
which may support brief sub-vfr conditions. Otherwise...VFR
conditions are expected to persist for a vast majority of the
week as dry low-level air dominates.