729
FXUS61 KPBZ 151558
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1158 AM EDT Wed Jul 15 2026

.WHAT HAS CHANGED...
No changes to the forecast.

&&

.KEY MESSAGES...
1) Above average temperatures and smoke persist late-week.

2) Storm chances, along with severe and flooding risks, return
into the weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...
Today is likely to be the hottest day of this week with a thin
vail of wildfire smoke aloft and a ridge breakdown expected into
late week. The heat advisory remains in effect until 8pm tonight
with a >75% chance of max temperatures >90F in the advisory
area, and a 30% to 60% chance of heat indices >100F, highest
for valleys and/or urbanized areas. Overnight temperature
recoveries will be lack-luster; with dew points in the upper 60s
to low 70s, lows in the low-to-mid 70s seem reasonable. This
correlates with major heat risk, affecting anyone without proper
cooling or hydration.

Thursday, there is high confidence that near-surface smoke
concentrations will increase from wildfires originating in
southern Ontario and northern Minnesota. Exact concentrations of
smoke will depend on the exact intensity of upstream fires, but
current thoughts show moderate air quality degradations, though
not as severe as the smoke event from June 2023. Smoke will
progress in from the north, with concentrations rising for the
I-80 corridor at sunrise; southwest PA, east OH, and the
northern WV panhandle mid-morning; and northern West Virginia in
the early afternoon.

Smoke may actually knock 2-3 degrees off forecast high
temperatures, slightly reducing heat risk from the day prior.
Temperatures are expected to fall back to near-normal for the
weekend. Near surface smoke is expected to linger until more
flow or rain clears it out. At this point, modeling has it
through at least Friday, but bouts may last through the weekend.

KEY MESSAGE 2...
The ridge breakdown will occur during the Friday and into
Saturday period. This will tend towards a pattern of western
ridging and eastern troughing, along with cooling temperatures
into Saturday, Sunday, and early next week.

Ensemble clustering is in good agreement in the general flow
through the weekend. The main uncertainty will be 1) the
presence of a shortwave trough late Friday and 2) the timing and
position of a shortwave trough Saturday.

GFS dominated ensembles show a shortwave passage late Friday
that would result in heightened convective coverage Friday
afternoon in low cape environment with most flow in the mid-
levels. This could result in some convection, but relatively
low severe chances with DCAPE less than 600. Mid-level flow
might also be progressive enough to mitigate flood risk unless
training exists. All this to say, that this point it is
generally more likely in low to no convective coverage at all,
with Canadian and Euro based ensembles showing a lack of a
shortwave altogether.

Severe and flood chances now definitively maximize on Saturday
with higher confidence of a shortwave passage. In the scenario
where the shortwave is stronger, much of the threat may be
focused to regions southwest of Pittsburgh (GFS scenario), with
severe chances relativity higher and flood risk slightly lower.
In the event that the shortwave is weaker, the threat may be
focused near and northeast of Pittsburgh with severe chances
relatively lower, but flooding risk higher. The reason for
this: stronger flow and forcing aloft is more favorable for
severe convection but worse for flooding via training storms
(and vise versa). Because of this, theoretically all threats are
on the table but certainty may increase as trough intensity is
refined.

As for flood risk, LREF 50th percentile PWATS will be >90th
percentile, and convection may be boundary parallel as it moves
from the northwest to southeast in a weaker or multi-axial
trough passage. Model soundings show long, skinny CAPE. There
are some particularly high-QPF analogs in similar patterns, and
NBM 90th percentile to max QPF shows 2-5" is certainly possible
somewhere.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR persists under the influence of upper level ridging with
subtle reorientation of the surface pressure field to yield a
wind field that veers from SW to NW by the afternoon with
occasional gusts 15-20kts.

Wildfire smoke likely remains lofted at cirrus levels through
the majority of the TAF period before reaching near the surface
at or just after the TAF period, spreading south. Enough
particulates may be present to aid localized fog formation prior
to dawn for locations with better near-surface moisture or
nearby rivers (ZZV/HLG/MGW).

Outlook...
High pressure maintains VFR through the majority of the majority
of Friday with little in the way of Cu development. However,
wildfire smoke from far northern Minnesota and western Ontario
may filter towards the surface starting Thursday and cause
haze/smoke-related visibility reductions (probably no lower than
MVFR) that could extend into Friday and beyond, pending smoke
density.

Thunderstorm chances return late Friday into the weekend as
upper level shortwaves traverse the region.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT this evening for PAZ007-008-
     013>015-020>022-029-031-073-075-077.
OH...Heat Advisory until 8 PM EDT this evening for OHZ039>041-
     048>050-057>059-068-069.
WV...Heat Advisory until 8 PM EDT this evening for WVZ001>004-012-
     021-509.

&&

$$

DISCUSSION...Milcarek
AVIATION...Frazier