PBZ issues Area Forecast Discussion (AFD) at Oct 25, 1:34 AM EDT831
FXUS61 KPBZ 250534
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
134 AM EDT Sat Oct 25 2025
.SYNOPSIS...
Near-to-below average temperatures through the weekend with frost and
freeze concerns each night through next week. Forecast certainty
decreases mid-week.
&&
.NEAR TERM /THROUGH TODAY/...
KEY MESSAGES:
- Pleasant and seasonably cool day today.
- Frost and freeze concerns tonight.
---------------------------------------------------------------
The freeze warning this morning remains in effect though the
probability of actually achieving freezing temperatures in most
areas encompassed in the warning has decreased. Shallow
moisture in weak northwest flow has continued to allow a thin
stratocumulus deck that is expected through morning over the
northwest half of the area. Confidence in a widespread freeze
remains highest in eastern Ohio and northern West Virginia (50%
to 70%), slightly lower into western PA with bullish cloud cover
(30% to 50%).
Inversion breaking and a morning warmup is forecast, though
consequently, high clouds are expected to impinge from the
south into the day today. In areas south of I-80, for the first
time in days, low cloud cover may remain more scattered that
broken/overcast in very shallow near-surface moisture and
shortwave ridging. North of I-80, continued weak northwest flow
will continue to stream clouds and perhaps even a few light
showers in the farthest northern portions of the forecast area
in lake moisture. Highs are forecast to remain slightly below
normal with 850mb temps 6-7C below normal.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
KEY MESSAGES:
- Near-to-below average temperatures; low rain chances.
- Frost and freeze chances each night.
----------------------------------------------------------------
Overnight Saturday, there may be just enough moisture under a
shortwave trough to provide a last-gasp chance of showers north
of I-80. With northerly wind filling in behind, the presence of
nocturnal clouds will be up to chance, but highest north of
I-80. This will again affect frost and freeze chances. A frost
is 60% to 80% likely in areas without clouds, but a freeze will
depend on being cloud free and getting cool enough, only 30% to
50% likely for now across much of the area.
Apart from high clouds impinging from the south and perhaps some
fair weather diurnal cumulus, Sunday and Monday will be pleasant
with temperatures nearing normal, though likely continuing to
sit just below seasonal highs. Surface high pressure will
prevail, limiting rain chances. There is roughly a 50% to 90%
chance of a freeze Sunday and Monday night northeast of
Pittsburgh, with frost chances each night across much of the
rest of the area.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
KEY MESSAGES:
- Moderate uncertainty in the mid-to-late week forecast, though
trends have leaned cooler and wetter.
-------------------------------------------------------------------
Models have come into slightly more agreement on the long term
pattern (Tuesday and beyond), with temperature and
precipitation spread decreasing and honing in on continued high
temperatures in the 50s, nightly frost/freeze chances, and
precipitation chances increasing Wednesday into Thursday. But
nonetheless, there is still moderate uncertainty.
The nuance from exact how reality pans out will depend on
exactly how a closed low of the coast of New England and an
approaching western trough develops into a cut-off low. The main
scenario is that the trough approaches, cuts off over the
central CONUS, pulls the New England closed low back west, and
cyclogenesis occurs as the surface low develops on the eastern
side of the cut off and moves north, deepening as it occludes.
Even in this scenario, there is still timing and position
uncertainty in when this might occur, but most models have this
process taking place in the Wednesday-Thursday- Friday window
with cyclogenesis and rain favored over the forecast area. This
scenario makes up ~70% of LREF clustered guidance. This
scenarios would spell cool and wet.
The second most likely scenario is that the cut off low
develops, but dives too far into the southeast to have major
affect over the area as surface ridging develops overtop of
this. This would alienate much of the influence of the New
England closed low, and allow it to remain separated from the
impinging trough. This would both delay rain chances later, and
keep the area comparatively warmer and drier late week. This
encompasses ~30% of LREF membership. Should this occur, the cut
off low may just pass to the east (along with the rain chances)
as it rejoins flow, or rejoin earlier and bring a brief bout of
rain chances next weekend.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions will continue to dominate in most cases through
Saturday night. A stubborn stratocumulus deck is still expected to
slowly erode from the southwest overnight past sunrise as troughing
pulls off to the east and flat ridging builds in. FKL/DUJ may still
experience brief periods of MVFR through 18Z, and a light rain
shower through 09Z or so, but ceilings should remain above 3k feet
south of I-80. By afternoon, high clouds will be most prevalent.
Wind remains light and fairly variable overall as surface high
pressure builds in.
.OUTLOOK...
Areawide VFR continues through the weekend as 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 until 9 AM EDT this morning for PAZ020-021-029-
031-073>076.
OH...Freeze Warning until 9 AM EDT this morning for OHZ039>041-
048>050-057>059-068-069.
WV...Freeze Warning until 9 AM EDT this morning for WVZ001>004-012-
021-509>514.
&&
$$
SYNOPSIS...Milcarek
NEAR TERM...Milcarek
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...CL
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 25, 1:34 AM EDT---------------
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