PBZ issues Area Forecast Discussion (AFD) at Oct 24, 1:42 PM EDT
722
FXUS61 KPBZ 241742
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
142 PM EDT Fri Oct 24 2025
.SYNOPSIS...
Lake-effect showers taper tonight into Saturday. Frost and
freeze concerns continue each morning through the weekend.
Large forecast uncertainty develops mid-to-late next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Lake-effect showers taper off north of I-80 after sunset
- Frost and freeze concerns return tonight
---------------------------------------------------------------
The upper trough over eastern Canada begins to shift east
tonight, resulting in a shift to northwest flow which will help
filter drier air into the area. As a result, lake-effect showers
will gradually taper overnight.
The main concern tonight is the potential for frost/freeze
conditions across the area. Locations where clouds are able to
scatter/clear will determine where temperatures will be
coldest. North of Pittsburgh, persistent lake-effect clouds in
weak northwest flow (even after showers dissipate) should help
keep temperatures above freezing. Near and south/west of
Pittsburgh, it'll be a race between how fast clouds driven by
daytime heating/mixing can dissipate and how fast upper-level
clouds overspread the area from south to north ahead of low
pressure moving into the central Mississippi Valley. Latest
ensembles (both HREF and NBM) suggest the most likely area to
see a break in cloud cover between these features will be along
a belt of counties extending from roughly Coshocton/Tuscarawas
in eastern OH to Fayette/Westmoreland in southwest PA.
A Freeze Warning is in effect for that stretch of counties from
Midnight tonight until 9 AM Saturday morning. The Freeze
Warning also extends south into northern West Virginia, but
there is slightly less confidence that far south as high clouds
could move in and mitigate radiative cooling before temperatures
drop below freezing. Later shifts will need to monitor
satellite and temperature trends, and may end up needing to trim
the warning if that occurs.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Ending precipitation in northwest PA; dry otherwise
- Temperature rising toward seasonal average
----------------------------------------------------------------
A last upper level shortwave heading toward New England may be
enough to keep low probability lake effect showers during the
daytime hours Saturday north of I-80. Otherwise, high pressure
and subsidence over the Ohio River Valley is expected to support
dry weather. Though height rises should offer stronger
temperature moderation, a lifting southern stream trough
approaching the Tennessee River valley may provide enough high-
level moisture to limit insolation (along with lake-enhanced
diurnal cu) and act to temper some of the expected temperature
rises.
That trough will settle south of the region Sunday while ridging
develops over the western Great Lakes plus another deep trough
sits over northern New England. Wedged between these features
but remaining under the influence of surface high pressure means
dry weather continues for most of the area with a mix of sun and
clouds allowing temperature to be within a few degrees of
normal. Late day approach of the southern stream trough creates
low probability rain chances late Sunday night along the WV
higher terrain; if this occurs, low temperature may be more mild
than forecast and thus not result in any snow formation.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:
- Highly variable long range forecast that favors a trend toward
a cooler, more wet pattern
-------------------------------------------------------------------
The Upper Ohio River valley is likely to remain wedged between
the three upper level features (Great Lakes ridge, New England
trough, Tennessee Valley trough) Monday while awaiting notable
upper level energy to arrive from the Pacific Northwest. There
is reasonably high confidence for this to maintain seasonable
temperature and any precipitation chances remaining south of
I-70 depending on the degree of northward movement of the
Tennessee trough.
Cluster analysis of ensemble weather modeling for Tuesday into
late next week shows large variability in the broader 500mb
pattern evolution; current means and forecasted values follow a
trend of a potent upper trough phasing with the TN trough while
displacing the Great Lakes ridge northward and result in a
broader eastern CONUS trough axis. This portends a prolonged
period of below average temperature with periodic precipitation
chances with potential for enough cold advection to create WV
high terrain snow by the end of the week. However, that cluster
analysis shows trough positioning to stretch from as far west as
TX and as far east as the Atlantic coast; temperature profiles
range from above normal readings to well below normal readings
and precipitation chances (let alone amounts) wildly oscillating
from there. Additional model runs will be needed to better sort
out the highly variable pattern, but it does appear the
potential for impactful weather (likely tied to snowfall
accumulation) is very low.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR stratocu are ongoing across much of the area this afternoon,
save for lingering patches of MVFR ceilings in lake-effect
clouds from PIT/AGC up to FKL/DUJ. Widespread VFR is expected by
later this afternoon and should prevail through the rest of the
forecast period, though there remains a low probability for
ceilings to drop back to MVFR at FKL/DUJ overnight. Rain showers
taper off after dark as dry air begins to filter into the area.
Winds will be light and gradually shift to northerly and then
east-northeasterly tonight into Saturday.
.OUTLOOK...
Areawide VFR returns over the weekend as the trough axis shifts
east and weak ridging builds overhead. Another system could
return rain and restriction chances from the south early next
week.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Warning from midnight tonight to 9 AM EDT Saturday for
PAZ020-021-029-031-073>076.
OH...Freeze Warning from midnight tonight to 9 AM EDT Saturday for
OHZ039>041-048>050-057>059-068-069.
WV...Freeze Warning from midnight tonight to 9 AM EDT Saturday for
WVZ001>004-012-021-509>514.
&&
$$
SYNOPSIS...Cermak
NEAR TERM...Cermak
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Cermak
Source: PBZ issues Area Forecast Discussion (AFD) at Oct 24, 1:42 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202510241742-KPBZ-FXUS61-AFDPBZ)
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