Area Forecast Discussion
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FXUS61 KPBZ 241519
Area Forecast Discussion
National Weather Service Pittsburgh PA
1119 AM EDT SUN JUL 24 2016
Hot and humid conditions will continue. The best chance
for showers and thunderstorms will return on Monday with the passage
of a weak cold front. Above normal temperatures continue through the
week...however they should stay in the 80s.
.NEAR TERM /THROUGH MONDAY/...
Showers and thunderstorms over northern Ohio will hold together as
they move into an unstable airmass as noted by SPC meso-analysis
time lapse charts. This is consistent with new NAM and recent runs
from HI-RES convective allowing models. As a result, increased pops
to high chance and lower likely /45-60%/ for areas mainly north of
the heat advisory. The northern tier of counties contained in the
heat advisory could see a brief downpour and period of clouds.
However, with several hours of daytime in its wake opted not to
change anything with the headline. Previous discussion below...
A thunderstorm complex over Michigan will continue to advect east-southeastward
in response to a pocket of cooler mid level air. Steering winds
across lower MI are westerly then back northwest over Lake Erie.
This will carry what remains of the complex over our area this
afternoon. This creates two forecast challenges:
1) Thunderstorm coverage. The aforementioned areas of storms
crossing lower MI will be the trigger and focus by early afternoon.
The 12Z raob for PIT has a cap around 750mb which will erode later
today. With dewpoints climbing near 70F and afternoon temps in the
90s, plenty of energy to tap if storms get going. DCAPE values
around 1.0 kjkg-1 support the main threat being wet microbursts
and brief heavy rain. Storm motion vectors are around 20kts, so if
areas get hit more than once a flood threat does exist. HI-RES models
and HRRR experimental bring a line of showers and storms
commencing around 18z in NW PA and 22z in the far SERN part of our
2) Temperatures. Temperatures are already pushing 90F and a
modified sounding yields convective temps in the upper 80s. If
any place experiences a period of rain, it is still possible for
them to reach our forecast high. This was observed Saturday over
parts of the area, where rain and clouds did not stop the
thermometer from reaching the lower to mid 90s before the day was
done. Another record high temperature could be set for Zanesville
(3 in 4 days) this afternoon along with a few other sites. This
information is contained within the climate sub header found
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
A sweeping cold front will bisect the forecast area Monday night,
as the parent upper-level low shifts into the eastern Great Lakes.
The boundary will be slow to sag south of the area, prolonging
shower and thunderstorm chances into midday Tuesday. By Tuesday
afternoon, surface high pressure and drier air will invade from
the north and quell rain chances north of I-70. Wednesday is
expected to be mostly dry, with the exception coming in the ridges
where the elevated heat source could generate a few showers or
Relief from the recent high dewpoints will finally come with
fresh air behind the front. Dewpoints will drop precipitously into
the low to mid 60s by Tuesday afternoon, and upper 50s to low 60s
by Wednesday. Despite temperatures holding above average, the
lower dewpoints will feel much more comfortable than the current
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
- Continued above normal temperatures
- Best shot at rain arrives Thursday night into Friday
Overall no real change to synoptic pattern for much of the week
as a broad H5 anticyclone dominates the southern 2/3rds of the
CONUS. Our mid level height values will fall a few decameters,
but not enough to usher in temps where they should be for this
time of year. Based on H8 temps progs...do not see a stretch of
90F+ weather like this weekend. However, would not be surprised
for eastern Ohio to be right around 90F for daytime highs most of
Baroclinic zone that crosses Monday night weakens and washes out
over the central Appalachians Tuesday as flow become parallel to
the boundary and it encounters increased subsidence. In its
wake, slightly cooler weather than what we have experienced
takes hold for mid week. By weeks end, another shortwave trough
traverses the region sweeping a cold front through. Timing
differences reside with ECMWF and GEFS, but ECMWF keeps the
recent summer trend going of shortwaves passing outside peak
heating hours. GFS opts for a Friday afternoon passage. Either
way, the next shot of widespread precipitation appears to be
Thursday night into Friday. Zonal flow re-establishes for the
weekend with temperatures near the climo average of lower to mid
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Medium to high confidence forecast. IFR fog at AGC will lift by
13z owing to VFR much like remainder of the terminals through
early afternoon. Daytime heating combining with the thunderstorm
complex crossing the periphery of the H5 ridge in MI as of 1130Z
will lead to scattered thunderstorms this afternoon. While the
actual probability of a airport being directly impacted is
low continue with just CB mention. Diurnal cumulus clouds around
4KFT will develop by midday and persist through sunset.
Overnight mid and high clouds shall keep widespread ifr fog from
developing...however if an airport experiences a shower or storm
this afternoon then the chance of IFR fog increases.
.OUTLOOK /SUNDAY THROUGH THURSDAY/...
Restrictions will be possible Monday with the approach and
passage of a weak cold front.
Hot temperatures across the region today may approach record
levels at some sites. Here are a few selected records and
Site Forecast Record Year
Pittsburgh Int`l Airport 94 98 1934
New Philadelphia 97 94 1999
Morgantown 95 93 1987
Zanesville 96 95 1999
OH...Heat Advisory until 8 PM EDT this evening FOR OHZ039>041-
PA...Heat Advisory until 8 PM EDT this evening FOR PAZ020-021-029-
WV...Heat Advisory until 8 PM EDT this evening FOR WVZ001>004-012-