522
FXUS61 KPBZ 180555
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
155 AM EDT Sat Oct 18 2025

.SYNOPSIS...
Dry and unseasonably warm weather expected Saturday. A strong
cold front will bring showers, thunderstorms, and gusty wind on
Sunday. More seasonable temperatures return next week with
periodic rain chances.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- A few light showers north of Pittsburgh through dawn
- Dry and unseasonably warm today and tonight
---------------------------------------------------------------

A few light showers will rotate through the area tonight, primarily
north of US-422, where broad, weak ascent and better mid-level
moisture reside. Dry sub-cloud layer air should prevent more
than a few hundredths of an inch from these returns, and most
should see a dry remainder of the overnight hours.

Mid-level ridging will lose its grip today as a longwave trough digs
across the central CONUS. As the ridge is pushed east, deep layer
southwest flow establishes and increases moisture return, especially
in the latter half of the day once the surface high moves far enough
east to freshen up surface flow; dew points will start off the day
in the upper 30s and end the day in the upper 50s. Morning cloud
coverage should actually scatter out for a brief period this
afternoon as a pocket of mid-level dry air works in, and this will
allow highs to reach the upper 70s with even some 80 degree readings
sneaking up into southeastern Ohio where warm advection will be
strongest.

Overnight lows tonight will have a high floor with dews in
the upper 50s, increasing cloud cover, and a stiff southerly
gradient flow promoting values that will be right around our normal
*high* temperature this time of year. Can`t entirely rule out a
shower sneaking into our eastern Ohio counties on the periphery of a
weak front that will quickly strengthen and bring active weather
through here on Sunday, but chances are low.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Cold front passage Sunday offers high chance of rain and windy
  conditions
- A possible convective line on Sunday afternoon could bring
  damaging wind gusts and an embedded tornado threat
----------------------------------------------------------------

As the central CONUS trough deepens and progresses east, associated
surface cyclogenesis occurs across the Plains and rapidly lifts
northeast toward the Great Lakes riding along a pre-existing weak
boundary. The low will deepen rapidly and strengthen the boundary
pulling it through here as a cold front on Sunday afternoon. This
system will pack quite the dynamic punch and bring a two-fold threat
of severe weather and strong wind gusts with it.

The pressure gradient tightens between the aforementioned surface
low and and departing high pressure then centered offshore. Deep
layer flow through the entire column follows suit as 925 mb flow
jumps to 30+ knots and 850 mb flow to 40+ knots. Tapping into the
enhanced low-level flow and working in tandem with the tight
pressure gradient, wind will be quite gusty on Sunday. The latest
NBM continues to suggest a very high probability (>90%) for frequent
wind gusts exceeding 30 mph across our entire area. Probability for
occasional gusts over 40 mph continues its incremental increase now
up to 50-80%. Above that, probabilities quickly drop off, with
around a 10-20% chance of >50 mph, and thoughts are that this is
likely tied to potential gusts along a convective line of
showers/storms.

We`ve now gotten this event within the range of most all of the CAMs
to glean a better idea of how a narrow convective line along the
cold front may evolve. As has been the case for the past couple
days, limited instability still presents as the main hindrance
with thick cloud coverage in the morning and some pre-frontal
rain depicted by most of the CAMs which acts detrimentally for
destabilization. Very few are all that excited about more than
100- 300 J/kg of MLCAPE. Despite this, strong forcing both along
the front and synoptically with diffluent flow and shortwave-
aided ascent should be sufficient in tandem with the limited
CAPE to overcome the subpar thermodynamics. Deep layer shear
still remains around 50-60 knots with low level shear in the 0-3
km layer around 30-35 knots. Given this, think it`s plausible
that we see a narrow, low topped convective line along the cold
front that will bring a damaging wind and embedded tornado
threat. With such strong background flow, it won`t take much
convective enhancement to get to 60 mph gusts. Low level shear
vectors are southwesterly, so for embedded QLCS tornado threat,
will be most concerned about any segments of the line that
orient northwesterly to southeasterly to best utilize the
available shear. Of note, there may not be a lot of lightning
associated with this as thermodynamic profiles are well-
saturated through ~500 mb and modeled equilibrium levels are
hovering generally below -10C and therefore unfavorable for
charge separation.

With the passage of the cold front Sunday afternoon/evening, winds
shift to westerly and the severe threat ends. Breezy conditions are
expected to continue through Sunday night. Rain chances also
continue through Sunday night as low level cold advection reinforces
fumes of instability and we don`t work dry air in immediately behind
the boundary.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Cooler weather returns next week
- Periodic rain chances continue through the week
-------------------------------------------------------------------

Lingering showers should wrap up for most of the area on Monday
morning as the mid-level trough completes its passage and flow veers
to the west/northwest. Upslope enhancement with this direction and
still persistent near-surface moisture could continue to squeeze out
some drizzle in the ridges into the afternoon hours, but do think
that dry air wins out and most all of the area should return to
mostly clear skies by Monday evening.

High pressure then briefly slides by to our south and keeps most of
Monday night dry before another low pressure system makes its
entrance into the Great Lakes region early Tuesday. Seeing some
uncertainty both in timing and amplitude of the parent mid-level
trough, but that has decreased some in the most recent ensembles.
Feeling a bit more confident that the northern half of our area sees
higher rain chances arriving sometime during the daytime hours on
Tuesday in closest proximity to the surface low, but the majority of
the region could get in on some mostly light rain showers.

Fall looks like it returns by mid-week as the low departs with more
seasonable temperatures in store but still low-end rain chances
hanging around.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Confidence remains high for VFR conditions through the TAF
period as strengthening southwest flow promotes warm advection.
Early morning fog potential remains low due to limited
radiational cooling from the presence of mid to upper- level
clouds. High resolution model guidance also suggest minimal low-
level cumulus development this afternoon given prevailing
subsidence.

A low pressure system will move across the region between 15Z
and 23Z Sunday, bringing a likelihood of rain showers, isolated
thunderstorms, and gusty winds.

Strengthening warm air aloft Sunday morning will likely limit
surface wind gusts but increase the potential of LLWS
(35-45kts) due to a strong vertical wind profile. Between 16Z
and 23Z Sunday, a passing cold front will likely enhance the
downward mixing of strong winds aloft to the surface; gusts
could range from 35kts to 45kts.

.OUTLOOK...

Scattered to isolated showers are expected in the wake of the
cold front, accompanied by gusty winds. The likelihood of MVFR
to IFR cigs increases Sunday night into early Monday with cold
advection within the boundary layer under northwest flow.

High pressure will likely restore VFR conditions after sunrise
Monday and continue into the overnight time period.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...Hefferan