PBZ issues Area Forecast Discussion (AFD) at Jul 30, 8:05 PM EDT462
FXUS61 KPBZ 310005
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
805 PM EDT Wed Jul 30 2025
.SYNOPSIS...
Dry Wednesday night with some morning fog. More organized
storms cross tomorrow on a cold front with slightly higher
wind/flood threats. Cool and dry weather returns for the
weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
KEY MESSAGES:
- Another dry but muggy overnight period with lows near 10
degrees above normal.
- Areas of fog possible for the morning.
---------------------------------------------------------------
Slow moving showers and storms have begun to wind down as we
lose daytime heating this evening and will give way to a dry
overnight period. Have allowed the heat advisory to expire with
temperatures cooling off after sunset.
Poor temperature recoveries forecast tonight with surface dew
points in the upper 60s to low 70s limiting the floor for
radiational cooling, and increasing cloud cover from the
northwest through the overnight period won't help us in that
regard either. What the cloud cover may do is put a cap on how
dense the fog can get despite a similar environment to Tuesday
night. Still expecting the most development in areas it rained
on today, which again was confined mostly to northern West
Virginia, but HREF probability is less bullish on visibility < 1
mile tonight.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
KEY MESSAGES:
- Severe wind threats on a front passage Thursday, with some
flash flooding potential.
----------------------------------------------------------------
A cold front will begin its approach to the area through the
day on Thursday. The front will likely cross through northwest
Pennsylvania, in the morning, stretch east-west intersecting
Pittsburgh mid-day, then continue its passage through the
southwest PA, southeast OH, and northern WV through the
afternoon/evening.
There's some indication of a post-frontal 500mb shortwave passing
through the I-80 corridor in the late-morning hours, which should
supply mostly light to moderate stratiform rain with saturated, and
mostly stable low-level profiles as low- level cold advection forces
saturation and weakens mid-level lapse rates. HREF mean
precipitation from this round shows an area-wide 0.25 to 0.5
inches, through there may be evidence of a deformation zone,
with up to 1 to 2 inches possible. At this time, this is up near
Meadville, but in the event this is more aligned over Mercer
and Venango, it may pose marginal flood threats.
As for the pre-frontal environment, HREF 25th to 75th percentile
SBCAPE shows 1000-2500 J/kg CAPE, with much of the uncertainty tied
to the extent of cloud cover. Should CAPE be towards the higher end
of the distribution, it may be able to utilize the 800 to 1000 J/kg
of DCAPE, and make shear-parallel runs along the front (in north
south oriented segments), with up to 30kts of sfc to 6km flow. Shear
will mostly be straight line, some damaging winds in linear bits
will be the primary threat, although CAMs do indicate some weak
cyclonic curvature in the lowest 1km, which will mean tornado-
genesis could not be ruled out in right moving segments, though it's
generally unlikely. This severe potential is highest around, south,
and east of Pittsburgh in the best pre-frontal environment during
peak heating. Flooding threats may be lower and will be reliant on
training, though precipitation rates may be up to 1 to 2 inches per
hour in 1.8 to 2 inch PWATS in the fast moving segments, though
these rates will likely not last long. Hence, flood potential
remains low, most likely for urban and poor drainage areas.
The frontal passage drags south overnight, ushering in more
seasonable temperatures by Friday morning with patchy fog and low
stratus possible over much of the area.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- Cool and dry weekend; warmup next week.
-------------------------------------------------------------------
There is high confidence in a cool-down in post-frontal cold
advection on Friday, with even some potential that highs slightly
underpreform NBM with it's warm season bias. This will put much of
the area with highs in the 70s: a refreshing reprieve from hot and
moist. This trend will continue with high confidence through
Saturday and Sunday. High pressure, subsidence, cold low levels.
Some return flow is possible Sunday as highs may return to near-
normal.
Temperatures may return to near-to-above normal by mid-week and
flow orients more zonal, allowing low shower chances on
shortwaves, but there is actually some indication of more
troughing in all four clusters by the latter half of next week
again, which may hold off a return of grueling heat.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Expect any leftover convection this evening to dissipate by 01Z.
Increasing cloud cover is expected after midnight as a cold
front approaches from the west. Showers (and possibly a few
embedded rumbles of thunder) left over from this evening's
convection in Indiana will track eastward overnight and into
eastern Ohio and northwestern PA after 12z Thursday. These will
be accompanied by drops in cigs to MVFR, IFR, and LIFR first at
FKL/DUJ then gradually spreading southeast to other terminals
(except MGW) by the end of the TAF period. The onset of
heating/mixing after 15z will increase shower and thunderstorm
chances along and ahead of the front, which by that time should
be entering the local area from the west.
There is still some uncertainty with the arrival of showers and
thunderstorms tomorrow so have put PROB30's in for many of the
terminals. Hi-res trends now suggest the convection could be
delayed but as for the thunderstorm impacts, expected them to
end by 00Z tomorrow night. Winds will be rather light and
variable outside of thunderstorms.
Outlook...
Precipitation and restriction chances become more
widespread Thursday afternoon/evening with the approach and
passage of a cold front. High confidence in a prolonged period
of VFR (save for more river valley steam fog) with dry weather
Thursday night into the weekend.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...MLB/Milcarek
NEAR TERM...MLB/Milcarek
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...TC/Shallenberger
Source:
PBZ issues Area Forecast Discussion (AFD) at Jul 30, 8:05 PM EDT---------------
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