643
FXUS61 KPBZ 182321
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
721 PM EDT Sat Oct 18 2025

.SYNOPSIS...
Unseasonably warm weather continues tonight. A strong cold
front will bring showers, thunderstorms, and gusty winds on
Sunday. More seasonable temperatures return next week with
periodic rain chances and breezy conditions.

&&

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

- Unseasonably warm tonight
- An isolated shower or two possible west of I-77 before sunrise
---------------------------------------------------------------

Strengthening deep-layer southwesterly flow will begin to
transport low-level moisture back into the area, with dewpoints
climbing into the 50s by tonight. This, combined with increasing
cloud cover and a stiff southerly gradient flow, will result in
overnight lows remaining well above seasonal levels; in fact
they may be close to our normal *high* temperature this time of
year. Can`t entirely rule out a shower sneaking into eastern
Ohio counties (mainly west of I-77) towards sunrise ahead of a
strengthening front approaching our area from the west.

&&

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

- Cold front passage Sunday offers high chance of rain and windy
  conditions
- A possible convective line on Sunday afternoon could produce
  damaging wind gusts
----------------------------------------------------------------

As a 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
only a 10-20% chance of >50 mph, and thoughts are that this is
likely tied to potential gusts within a convective line of
showers/storms that should form along the cold front.

We`ve now gotten this event within range of most all of the
CAMs to glean a better idea of how that narrow convective line may
evolve. As has been the case for the past couple days, limited
instability is still 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 primarily a damaging wind 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 can`t completely rule out an embedded QLCS tornado threat,
but only if any segments along the convective line are able to
orient northwesterly to southeasterly (normal to the shear). Of
note, there may not be much lightning associated with convection
as thermodynamic profiles are saturated through ~500 mb and
modeled equilibrium levels hover generally below the -10C level,
which is unfavorable for ice production and 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 as low level cold advection reinforces fumes of
instability and we don`t work dry air in immediately behind the
boundary.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
KEY MESSAGES:

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

Lingering showers should taper across the region before sunrise
on Monday as the upper trough swings out of the area and
heights begin to rise. A northwesterly upslope flow regime could
help drizzle linger into the afternoon across our ridges.
Overall though, expect dry air to win out and skies are expected
to clear throughout the day and evening from west to east. High
temperatures are expected to be stunted across the region
Monday and return to near normal values after consecutive days
well above.

Another upper trough swings across the Great Lakes and impinges
on the region by Tuesday. Clustered ensembles still indicate
timing and positional uncertainty with this wave but seem to
favor a possible slower eastward movement as an upper low tries
to close off in the base of the trough. At the SFC another low
pressure system is expected to occlude in the northern Great
Lakes and push a developing triple point low and cold front
across the region. At this time the highest rain chances remain
north, closest to the low but lower end rain chances extend
southward across the remainder of the region along the front.

Temperatures look to drop again in the wake of this low mid-
week with below normal temperatures for this time of year and
continued low-end rain chances as shortwaves round the base of
the parent trough.

&&

.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
Confidence remains high in VFR conditions area-wide at least
through daybreak with high pressure being shunted to the east.
Encroaching clouds are expected to thicken and lower, however,
with the approach of the next system. An increasing pressure
gradient overnight over a decoupled surface is expected to
accelerate winds some aloft, though gusts are not expected to
approach LLWS tolerance. Come daybreak tomorrow, mixing is
expected to ensue, allowing momentum transfer to the surface
with wind gusts through much of the late morning and early
afternoon. Confidence in any LLWS wains, as mixing most likely,
but will continue to monitor for future TAF cycles.

The low pressure and rainfall are not expected to encroach the
area from the west until 14Z at ZZV (along with the first non-
zero chance of MVFR/IFR). A rapid cig fall is expected in
heavier showers and especially along a cold front that will pass
most ports in the afternoon hours. A couple hundred joules of
CAPE may also be enough to produce isolated bouts of lightning
within the line. Low level moisture and rapid surface cooling
may also result in some vis reductions to MVFR/IFR at times. It
is possible that some winds in the strongest, linearly oriented
parts of the cold front in a shower/storm may experience a brief
wind gust of up to 50kts, though most will not. This is most
likely in western PA and northern WV. Elsewhere, most of the
afternoon will be gusty with mixing into a LLJ. The most likely
maximum values will lie between 30kts and 40kts, but localized
higher gusts could not be ruled out.

The gustiest winds are most likely to depart after 00Z for ports
as the surface low sits overhead, but some winds may briefly
pick up again overnight to 20kt to 30kt as the pressure gradient
again intensifies on the backside of the low. Again, most of
the is expected to mix in adiabatic profiles, but even if there
is some surface decoupling, LLWS is possible. Showers and vis
restrictions may also linger in nocturnal cold advection.

.OUTLOOK...
The likelihood of MVFR to IFR cigs increases Sunday night into
early Monday with cold advection within the boundary layer.
High pressure will likely restore VFR conditions after sunrise
Monday, save perhaps FKL and DUJ with lake influence. Winds may
continue to be breezy through at least mid week as probabilities
for gusts exceeding 25 kts remain high (>60% chance) each
afternoon through Wednesday.

&&

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

&&

$$

SYNOPSIS...Cermak/MLB
NEAR TERM...Cermak/MLB
SHORT TERM...Cermak/MLB
LONG TERM...MLB/AK
AVIATION...Milcarek