534
FXUS61 KPBZ 161149
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
749 AM EDT Thu Oct 16 2025

.SYNOPSIS...
Frost and freeze potential continues early Thursday morning and
again overnight Thursday night. Dry conditions with gradual
warming of temperatures expected through Saturday before
widespread rain and gusty wind arrives with a cold front on
Sunday.

&&

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

- Dry with areas of frost early this morning
- Frost/freeze threat again Thursday night
---------------------------------------------------------------

Surface high pressure meandering over the Great Lakes region
continues to provide dry weather locally. Dew points are running
much lower tonight than they were 24 hours ago, and with clear skies
overnight, this should allow for efficient radiational cooling and
potential frost development. There still is a bit of an established
pressure gradient on the periphery of the high, so it`s possible
that we maintain a light puff of wind overnight that prohibits
complete bottoming out of temperatures but likely still enough for
frost. Thus, a Frost Advisory remains in effect through 9am for
most of the area save southeastern OH and outside of the WV ridges.

Low level flow out of the north on Thursday will promote weak cold
advection and the cooler Canadian airmass will settle in locally.
Heights will remain largely the same as we`re wedged between a ridge
to our west and closed low to our east in a mid-level omega block.
Despite plentiful sunshine, high temperatures will hold a few
degrees cooler than Wednesday right around or a touch below normal.

Another night of frost/freeze potential expected Thursday night now
with the core of the high closer overhead. Similar conditions to
Wednesday night will be the result with higher confidence in calmer
wind and colder overnight lows. The probability for the vast
majority of the area to see frost is high at 60-100% (lowest in the
urban areas). Freeze potential is higher as well with even lower dew
points allowing for a lower floor, though interestingly, the HREF is
not that excited for <32F with only a 20-40% chance north and east
of Pittsburgh likely owing to its progged slightly elevated wind.
Given the ongoing frost headlines Thursday morning, will allow the
next shift to make the final call on Thursday night`s frost/freeze
headlines so as to not confuse messaging.

&&

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

- Well above normal temperatures for the weekend
- Scattered showers possible Friday night
- Cold front passage Sunday offers higher rain chances and windy
  conditions
----------------------------------------------------------------

We`ll finally get some mid-level height rises locally as the ridge
axis shifts eastward. Surface high pressure remains situated
overhead and plenty of subsidence will keep dry conditions in place,
though clouds will be on the increase from northwest to southeast
through the daytime hours as some increase in mid and upper level
moisture rides around the ridge. We`ll bring some warm
advection/weak shortwave driven rain shower chances in late Friday
into very early Saturday, but this shouldn`t amount to a whole lot
with probability for >0.10" less than 25%.

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 Saturday night through Sunday night.
This will also result in a warming trend for temperatures Saturday
and Sunday, with highs climbing into the low 70s each day.

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% 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, though latest ensemble clusters still
show a very low confidence pattern with the majority of uncertainty
stemming from a timing issue with the parent trough. There`s about
an even split between those members who suggest it`s quicker and
through the area Sunday afternoon while the others hold it back
until later Sunday evening. This evolution will impact frontal
passage timing and potential thunderstorm development. This will be
a high shear/low CAPE setup with mean NBM SBCAPE 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 up to or
even in excess of 50 knots), so if any deep updrafts are able to
form, they will be in an environment that supports at least a
limited damaging wind threat, though such a high shear/low CAPE
environment lends question as to whether or not there could be
too much shear for the little CAPE in place. This will all be
ironed out more in the coming days. Flooding is of lower concern
at this time given the preceding drought conditions and only
around a 30% probability of exceeding an inch of rainfall
(mainly across eastern Ohio) per the latest NBM.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
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 Monday morning with lingering low level moisture
and cold advection reinforcing steeper low level lapse rates, and
the latest NBM offers 20-30% PoPs 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 THURSDAY THROUGH MONDAY/...
River valley fog this morning should quickly dissipate with the
onset of heating/mixing. VFR is expected throughout the TAF
period under high pressure. Winds out of the north-northwest
increase to near 10 knots this afternoon with a few infrequent
gusts to 15-20 mph, followed by light and variable winds
overnight into early Friday.


.OUTLOOK...
Surface high pressure with height rises aloft favor VFR into
Saturday before a series of shortwaves ahead of the next cold
front bring increased rain and restriction chances. Breezy
conditions are also possible on Sunday with strengthening
southwesterly winds ahead of the cold front. Latest ensemble
guidance suggests a >90% chance for gusts exceeding 30 mph
areawide and even a 70% chance for peak gusts to exceed 40 mph
in the PIT/AGC/HLG area (40-50% elsewhere across the area).

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory until 9 AM EDT this morning for PAZ007>009-
     013>016-020>022-029-031-073>078.
     Freeze Watch from late tonight through Friday morning for
     PAZ007>009-013>016-020>022-029-031-073>078.
OH...Frost Advisory until 9 AM EDT this morning for OHZ039>041-049-
     050.
     Freeze Watch from late tonight through Friday morning for
     OHZ041.
WV...Frost Advisory until 9 AM EDT this morning for WVZ001-002-
     509>514.
     Freeze Watch from late tonight through Friday morning for
     WVZ001-509>514.

&&

$$

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