353
FXUS61 KPBZ 171134
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
734 AM EDT Fri Oct 17 2025

.SYNOPSIS...
Dry weather is expected for most of the area through Saturday as
high pressure moves east across the region, though a weak warm
front will bring a chance for very light rain north and east of
Pittsburgh late Friday night. A strong cold front will bring
showers, possible thunderstorms, and gusty wind on Sunday.

&&

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

- Increase in cloud coverage this afternoon
- Highs right around normal
- A few showers around late tonight
---------------------------------------------------------------

Light to calm wind has allowed temperatures to drop off into the 30s
across the area tonight under clear skies. This will allow for more
widespread frost development and sub-freezing conditions, and
thus the ongoing Frost/Freeze products remain in effect through 9am.

Surface high pressure centered directly overhead will slowly migrate
east through the day today. Strong subsidence maintains dry weather
while mid-level height rises and a bump up in thicknesses will
result in warmer afternoon high temperatures in the mid to upper
60s. Clouds will be on the increase from northwest to southeast
through the daytime hours as mid and upper level moisture rides
around the ridge.

We`ll bring some warm advection/weak shortwave driven rain shower
chances in late tonight as the ridge axis slides off to the east as
quick as it arrived. Given the weak forcing and dry sub-cloud layer
air, this shouldn`t amount to a whole lot. HREF probability for
measurable rain is relatively high especially along I-80 and to a
lesser extent down the ridges north of US-22, so it`s likely that a
few showers are around, but light at best as probability for >0.10"
peaks around 30%. It`ll otherwise be about 10 degrees warmer than
Thursday night with mid 40s lows.

&&

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

- Well above normal temperatures for the weekend
- Cold front passage Sunday offers higher rain chances and windy
  conditions
----------------------------------------------------------------

Saturday will be a transition day of sorts as a more complex pattern
begins to take shape. A trough deepens over the central CONUS and
pushes the narrow upper ridge over the eastern seaboard eastward
over the Atlantic. A rather potent shortwave ejects eastward from
the central Rockies during the day Saturday, traversing the Plains
and reaching the Mississippi Valley overnight Saturday into early
Sunday morning. Meanwhile, a surface low develops in the IA/WI/IL
vicinity, which rapidly deepens and lifts northeast towards the
Great Lakes, eventually becoming vertically stacked beneath the
parent shortwave. As all of this occurs, it causes deep-layer
southwesterly flow to strengthen downstream over the Ohio Valley and
lower Great Lakes, which in turn brings moisture and unsettled
weather back to the local area on Sunday. This will also result in a
warming trend for temperatures both Saturday and Sunday with
Saturday the warmest day in the mid to upper 70s.

Sunday`s forecast becomes more interesting with a dynamic system
bringing a two-fold threat. First, the stacked low moves closer in
proximity to the local area as it crosses the Michigan lower
peninsula and southern Ontario, which will cause the pressure
gradient between it and a broad surface high centered off the
southeastern U.S. coast to tighten. In addition, ensembles suggest
the deep-layer flow to be quite strong as expected this time of year
with around a 50-60% chance for 925 mb wind to exceed 35 knots which
forecast soundings suggest will be easily mixed down to the surface.
This will result in an uptick in non-convective winds. Latest
probabilities for max wind gusts exceeding 30 mph on Sunday are have
increased notably across the entire area with 80-100%, while
probabilities for max gusts exceeding 40 mph have followed the same
trend up to 40-70%. The second hazard will be showers and
thunderstorms associated with this system. A cold front will pass
through sometime on Sunday but still just not seeing great agreement
among latest ensembles which show temporal uncertainty stemming from
a timing issue with the parent trough. Some suggest it`s quicker and
through the area Sunday afternoon while others hold it back until
later Sunday evening. Another complicating factor to what extent of
showers/storms can fire along the front will be the potential for a
batch of rain preceding it to muddy the later day evolution. This
will be a high shear/low CAPE setup with mean NBM SBCAPE hovering
around 200-400 J/kg and 90th percentile values (contingent on any
low probability scattering of clouds) sneaking up as high as 600
J/kg. Deep layer shear will be strong (LREF mean sfc-500mb shear
ranging from 50-60 knots). Under the assumption that we`re able to
get a line of stronger convection along the boundary, the
environment will be favorable for at least a limited damaging wind
threat. It`s still also just as possible that the environment
is too muddied for stronger convection and we`re instead left
with some frontal showers. This will all be ironed out more in
the coming days as CAMs become available.

&&

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

- Cooler weather returns next week
- Periodic rain chances for the first half of the week
-------------------------------------------------------------------

Notable upper level pattern discrepancy continues and increases into
next week with some ensembles holding the trough back and closing it
off into an upper low while others quickly progress it offshore as
an open wave. The slower, deeper solution could result in rain
chances remaining on Monday with low level cold advection and
periodic shortwave passage while a quicker one allows high pressure
and drier air to sneak in quicker. Think that we likely will keep
some showers around especially on Monday morning with lingering low
level moisture and cold advection reinforcing steeper low level
lapse rates, and the latest NBM offers 20-30% PoPs into early
afternoon which seems reasonable at this juncture.

High pressure does eventually build behind the departing low, though
how long it stays around is uncertain as ensembles develop another
surface low off to our northwest with additional rain chances
returning as early as Tuesday. Given cascading differences among
solutions even for this coming weekend, confidence beyond that
timeframe is very low at this time.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
With surface high pressure centered over the Ohio River Valley this
morning, VFR conditions are expected to prevail across the region
with light and variable winds. Confidence remains high that mostly
clear skies will persist through mid-afternoon Friday before mid to
high-level clouds begin to increase from the west as a trough
approaches the Great Lakes region.

There is a chance for light rain/drizzle to pass north of Pittsburgh
between 02Z and 10Z Saturday, though probabilities remain too
low to warrant inclusion in TAFs this cycle. Even in instances
of rain, ceilings are expected to remain VFR given the presence
of sufficient dry air in the low levels.

.OUTLOOK...

A low pressure system will move across the region Sunday,
bringing widespread precipitation and associated reductions in
cigs and vis. A strong gradient wind field accompanying this
system will likely result in increasing sfc winds after sunrise
Sunday. By mid-afternoon, thunderstorm chances will rise ahead
of the approaching cold front, and depending on environmental
conditions, some storms could reach severe criteria.

In the wake of the front, periods of rain showers, lower cigs,
and gusty winds may persist into Monday.

 &&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory from 2 AM to 9 AM EDT Friday for PAZ007-013-020-
     021-029-031.
     Freeze Warning from 2 AM to 9 AM EDT Friday for PAZ008-009-
     014>016-022-073>078.
OH...Frost Advisory from 2 AM to 9 AM EDT Friday for OHZ039>041-
     048>050-057>059-068-069.
WV...Frost Advisory from 2 AM to 9 AM EDT Friday for WVZ001>004-012-
     021-509-510.
     Freeze Warning from 2 AM to 9 AM EDT Friday for WVZ511>514.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory until 9 AM EDT this morning for PAZ007-013-020-
     021-029-031.
     Freeze Warning until 9 AM EDT this morning for PAZ008-009-
     014>016-022-073>078.
OH...Frost Advisory until 9 AM EDT this morning for OHZ039>041-
     048>050-057>059-068-069.
WV...Frost Advisory until 9 AM EDT this morning for WVZ001>004-012-
     021-509-510.
     Freeze Warning until 9 AM EDT this morning for WVZ511>514.

&&

$$

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