883
FXUS61 KPBZ 122347
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
747 PM EDT Tue May 12 2026

.WHAT HAS CHANGED...
Low probability severe chances remain for Wednesday afternoon,
with little change in the range of potential outcomes.
Confidence in a pattern shift towards summer-like weather this
weekend continues to increase.

&&

.KEY MESSAGES...
1) Rain returns overnight into Wednesday morning with a second
shot of showers Wednesday afternoon that offers a low
probability severe threat.

2) Long-range outlook favors a notable pattern shift that
creates summer-like conditions across the Ohio River Valley
region.

&&

.DISCUSSION...
KEY MESSAGE 1...
Models continue to agree that a shortwave trough, currently
positioned near the western end of Lake Superior, will dig
across the rest of the Great Lakes region by tomorrow morning
and swing across the Upper Ohio Valley Wednesday night and
Thursday. An associated occluding surface low tracks near or
just north of Lake Ontario through tomorrow, dragging the
system`s triple point into New York State.

Rain should spread into the region from the northwest after 06Z,
but lift may be on a downward trend as 500mb/700 flow weakens
and as more favorable isentropic ascent fades. Thus, rain
coverage/intensity may be on the downswing as it moves east
across PA/WV. There still appears to be a rain-free period of at
least a couple of hours across most of the region. Plenty of
cloud cover should remain in the morning though, at least
initially. What happens to that cloud cover after is the key to
the potential for strong convection tomorrow: how much clearing,
and thus destabilization, occurs during the late morning/early
afternoon ahead of the cold frontal passage?

The potential surface-based CAPE values in that narrow warm
sector range from 300-400 J/kg on the lower end (in cloudier
scenarios) to around 1000 J/kg on the higher end (in sunnier
scenarios) of the envelope presented by the 12Z HREF. The
expected 0-6km shear levels of around 30 knots, while not
excessive, should be sufficient to support some level of
organized convection, and indeed the CAMs broadly agree on a
line along the front of varying strengths. The reasonable
outcomes range for a line of mostly showers with little
lightning, to a more robust line of thunderstorms that could
present a threat of isolated to scattered damaging wind gusts.
Sentiment continues to lean a bit more towards the lower-end,
less severe scenarios, although the CAPE range on the HREF did
show an upward tick on the lower percentile values. Mid-level
lapse rates/elevated CAPE appear insufficient for large hail,
and hodographs do not appear too favorable for a tornado threat.
Heavy rainfall is not a concern either, as 48-hour
probabilities of 1" of rain through 00Z Friday are mostly 20-25%
or less.

KEY MESSAGE 2...
Temperature again falls well below normal after Wednesday`s
cold front, with residual NW flow resulting in scattered
afternoon showers and highs struggling to even reach 60 (roughly
10 degrees below average) Thursday. Frost/freeze risks are
negligible Wednesday and Thursday nights given lingering wind
and cloud cover. Only eastern Tucker County has any appreciable
risk of falling below 36 degrees either night, and neither
appears to support ideal radiational cooling. In fact, there is
a very good probability that last night was the last
frost/freeze event for the season.

Ensembles continue to advertise a notable pattern shift this
weekend and early next week, with zonal flow Friday
night/Saturday followed by rising 500mb heights and ridging. The
overall confidence in a ridging pattern is high, but its
strength and timing remain at odds among the various model
clusters. Still, a return to seasonal temperatures is likely
Friday, followed by well-above normal values for the remainder
of the forecast period. By Sunday and Monday, we could be
looking at high temperatures some 15 to 20 degrees above normal.
There is high confidence in readings well into the 80s in most
areas by early next week, with even some potential to crack the
90 degree level in toastier spots. Temperatures may be modulated
at times by potential rainfall periods that remain hard to time
at this distance. Long-range machine-learning guidance from
NCAR and CSU depict broad, low-end risks for severe storms
through the period that will need to be refined over the coming
days.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
High confidence VFR prevails through 06z tonight. Generally
light west-southwesterly winds around 5-10 knots will back more
southerly overnight into early Wednesday.

This evening, a cloud deck around 7.5-10kft will move in ahead
of the low pressure system as winds freshen up after midnight.
By early morning hours, showers will move into the area.
Dwindling forcing for this rain leaves some question as to how
far east it gets and TEMPOs for these showers have been included
at LBE and DUJ. After rain moves out of the area late morning,
ceilings are forecast to drop to MVFR for a couple of hours at
most ports. IFR remains a low probability and some high-res
models hint that drops to MVFR could be rather short lived.
Considering how dry we start and the possibility that morning
showers under perform, it is easy to see where this possibility
arises.

By daylight, southwesterly wind is forecast to gust up to
20-25kts. There should be several long dry hours for most
locations before showery activity resumes in the afternoon. At
some locations this dry period is broken by PROB30 groups. As
mixing occurs and showers resume, MVFR CIGs are expected to lift
at affected ports. By mid-to- late afternoon, models indicate
thunderstorms popping across the region and possibly forming
into a more organized line. Thunderstorm intensity in the
afternoon depends on clouds in the morning. With more clearing,
storms can become more intense and lead to damaging wind gusts.
With more rain and less clearing in the morning, storms are less
organized and less heavy in the afternoon.

Outlook...
Restrictions will persist into Thursday morning due to the
crossing low pressure. VFR returns Thursday evening into Friday
under high pressure.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.

&&

$$

DISCUSSION...CL
AVIATION...AK