PBZ issues Area Forecast Discussion (AFD) at Oct 22, 12:58 AM EDT
855
FXUS61 KPBZ 220458
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
1258 AM EDT Wed Oct 22 2025
.SYNOPSIS...
Lake enhanced precipitation and cooler than average conditions
are likely to persist through Friday as an upper-level trough
lingers over the Great Lakes. Drier weather is anticipated this
weekend as a ridge builds over the region.
&&
.NEAR TERM /THROUGH TODAY/...
KEY MESSAGES:
- Light rain chances decrease before dawn with an exiting
shortwave
- Lake enhanced precipitation is favorable north of Pittsburgh
this afternoon
---------------------------------------------------------------
A weak shortwave embedded within a broad trough will continue to
progressing eastward early this morning. Light showers or
sprinkles will persist through 4am before drier conditions
return under mostly cloudy skies. Limited radiational cooling
will keep temperatures in the upper-30s/low-40s, minimizing the
potential for frost formation.
By early afternoon, another shortwave is expected to move across
Lake Huron and Erie, prompting the development of additional
rain showers. The probability of measurable rainfall remains
high (over 90%) north of Pittsburgh, with rainfall totals
between one-tenth and one-quarter inch likely north of I-80
through sunset.
Lightning chances will remain concentrated near Lake Erie today,
due to relatively warm surface waters generating instability
beneath colder air aloft (cold advection).
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
KEY MESSAGES:
- Below normal temperature and scattered shower activity both
Wednesday and Thursday
- Potential frost/freeze Thursday night, most likely near and
south of I-70
----------------------------------------------------------------
Mid-level troughing becomes the dominant feature over the Great
Lakes and northeast CONUS during this period. Cold advection and
a decent surface pressure gradient will maintain blustery
conditions on Wednesday, and to a lesser extent on Thursday as a
surface low pulls a bit further northward into Canada. We will
also see the season's first run of subzero 850mb temperatures.
Scattered to numerous lake-enhanced showers are likely during
this period. For now, the PoPs follow NBM suggestions. However,
given low-level flow out of the west or west-southwest, greater
activity is likely closer to the shore of Lake Erie - or more
precisely for our forecast area, north of I-80. So, the
north/south gradient of precipitation probabilities may need to
be tightened up in subsequent forecast issuances. In any case,
rain amounts do not shape up to be excessive. More than likely,
any 48-hour rain totals of half an inch or higher will be
confined to areas north of Pittsburgh. Some modest terrain
enhancement is also possible, especially if low-level flow can
tip a little closer to northwest on Thursday. Given the subzero
850mb temperatures, a few snowflakes may fly on the eastern
Tucker County ridges mainly after dark, but no accumulation is
foreseen.
Cloud cover and ongoing wind will negate any frost/freeze
concerns Wednesday night. Thursday night could be more favorable
as wind starts to slacken off. The threat area will also depend
on where clouds are able to decrease. For now, this appears to
be areas near and south of I-70, but could end up further north
depending on the eventual cloud boundary.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
KEY MESSAGES:
- Showers end Friday; drier through Saturday
- Frost/freeze conditions again possible Friday night
- Seasonable temperature and rain chances may return as early
as Sunday but uncertainty reigns
-------------------------------------------------------------------
Ensemble guidance continues to suggest that the trough axis will
shift to near or off of the Atlantic Coast by Friday morning, while
surface high pressure centers over the Middle Ohio Valley.
Northwest-flow showers may continue to linger through the morning,
but cloud cover and precipitation will likely trend downward through
the day with mid-level flow going more zonal. This dry pattern is
likely to continue through at least Saturday, with temperatures
remaining several degrees below normal. Friday night may feature
a more widespread area of frost/freeze conditions with minimum
temperatures again in the lower to mid 30s and light wind,
although patchy cloud cover could be a hindrance.
Pattern uncertainty begins to increase thereafter. A mid-level ridge
likely remains in place Sunday morning, extending from the Lower
Great Lakes across the Ohio Valley. A trough/closed 500mb low may
track across the southern Plains and Lower Mississippi Valley during
the day, while another shortwave trough potentially drops across the
Great Lakes. Clustered guidance offers varied solutions on how these
systems react. A sturdier ridge would lead to lower rain chances
and potentially warming temperatures, while cooler temperatures and
more rain are possible if shortwave influence is greater. For now,
will run with NBM mean suggestions, which involved some low rain
chances and fairly seasonable temperatures overall.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Our dry several hours is quickly coming to a close as a line of
showers and storms move eastward through Ohio along a cold
front.
This line can bring wind gusts up to 25-35KTs to area ports. At
this time FM groups have been used in ZZV but other ports have
remained TEMPOs. TEMPOs will be replaced with FM groups over the
coming hours as the line moves east. Hi-res modeling shows this
line beginning to fracture as it progresses eastward and we
will continue to monitor this trend. These showers and storms
are expected to pass with VFR CIGs and possible drops to MVFR
VIS in rainfall. Behind the cold front gusts can remain elevated
in the 15-25KT range for an hour or so before winds settle back
into synoptic values.
Cold advection after frontal passage is likely to better
support broken/overcast stratocu that fluctuates between low
VFR/high MVFR. Persistent upper troughing and cold advection
will allow for rounds of showers for parts of northwest PA
through Wednesday, but the upper dry slot will limit
coverage/duration of an isolated showers that can develop amid
diurnal afternoon heating. Wind will remain breezy through the
period out of the WSW, peaking in consistent gusts between
15z-22z Wednesday.
.OUTLOOK...
Persistent upper troughing over the Great Lakes through Thursday
will favor scattered to broken stratocumulus between 2kft-5kft,
breezy winds that peak during the afternoons, and lake enhanced
showers that favor terminals north of Pittsburgh.
High pressure builds over the region by Friday night to end all
precipitation chances and cement VFR conditions through
Saturday. The weather pattern thereafter becomes more uncertain
but poses potential for additional rain/restriction chances.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...CL
LONG TERM...CL
AVIATION...Frazier/AK
Source: PBZ issues Area Forecast Discussion (AFD) at Oct 22, 12:58 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202510220458-KPBZ-FXUS61-AFDPBZ)
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