PBZ issues Area Forecast Discussion (AFD) at Sep 21, 1:39 AM EDT
030
FXUS61 KPBZ 210539
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
139 AM EDT Sun Sep 21 2025
.SYNOPSIS...
Above normal temperatures will continue through the weekend.
A few showers and storms will be possible Sunday, but the
better chance for more widespread precipitation will arrive
later on Monday and continue through mid-week.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
KEY MESSAGES:
- Isolated showers/storms tonight
- Continued above normal temperatures
---------------------------------------------------------------
Convection from the afternoon and early evening continues to
diminish, with cloud tops warming and radar returns decreasing.
The latest upper air analysis shows a weak shortwave trough
across Ohio. This is expected to cross the area overnight, with
isolated showers. There is still some elevated instability
progged overnight, with Showalter indices around -1, so an
isolated rumble of thunder is possible.
Otherwise, mostly cloudy skies are expected for much of the
night, through some partial clearing will likely move eastward
behind the next shortwave. Patchy fog is possible where rain
occurred earlier today as well. Low temperatures are expected
to be 5 to 10 degrees above average.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
KEY MESSAGES:
- Additional showers/storms possible later Sunday in eastern
Ohio
- Temperatures remain above normal
----------------------------------------------------------------
Saturday's stalled boundary is progged to lift north with increasing
southerly surface flow and given an extra kick by the aforementioned
shortwave energy. This will allow for an increase in temperatures
and dew points with a summer-like feel with mid to upper 80s for
highs and low to mid 60s for dew points. Meanwhile, modest mid-level
height falls will occur on Sunday as shortwave energy rotates
through the Great Lakes regions. This is expected to initiate
initially disorganized scattered showers and thunderstorms across
the Ohio Valley in the early to mid afternoon hours that will slide
north and east into the evening and eventually into our eastern Ohio
counties closer to sunset. Coverage and organization should increase
a bit headed into the evening hours with better deep layer shear as
a broad south/southwest 20-25 knot low level jet develops beneath
increasing veering flow up to 700 mb. HREF prob for >1000 J/kg
SBCAPE and 20 knots of deep layer shear reaches 40-50% which could
point toward a low end wind threat, though latest CAMs suggest
arrival time around sunset in our eastern Ohio Counties. SPC day 2
outlook has encompassed those counties in a Marginal Risk (1/5) for
damaging wind, but a lower severe threat is a plausible solution
in our area if arrival time does prove to be after sunset.
Additional shortwave movement will support a continued chance of
showers overnight. Warm advection with elevated southerly flow
likely means lows won't dip out out of the 60s across the area save
north of I-80.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
KEY MESSAGES:
- Measurable rain expected within the long term period
- Near average temperatures expected late week
------------------------------------------------------------------
Confidence is high that a ridge axis over the Northeast will
dissipate as a trough ejects into the Great Lakes region. This
will result in an increase in southwest flow, leading to
elevated dew points and enhanced vertical wind shear and
increase our chances for showers and thunderstorms during this
time period. As for timing, precipitation chances will increase
across the Ohio River Valley beginning early Monday morning and
persisting into Tuesday.
Through early Tuesday morning, global ensemble guidance
indicates a probability exceeding 60% for at least a quarter
inch of precipitation for areas north of Pittsburgh and into
eastern Ohio. The probability of one inch of rain is considered
low over the 24 hour time period (less than 15%). As we progress
into the mid to late week time period, the potential for
additional rainfall and near- normal temperatures is noted due
to a lingering upper-level low centered to our southwest.
Overnight low temperatures may remain 5 degrees above average
with lingering low-level moisture and increase coverage.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
Dry weather is expected for the remainder of the overnight and
most of the day, though an isolated stray shower may still be
possible. Winds will remain light and variable overnight. Fog is
possible, but low probability, at MGW near sunrise.
Additional convection is expected later today with a crossing
shortwave, but latest CAM runs have pushed this activity later
than previously expected. Accordingly, have dropped PROB30
groups from TAF mention for all put ZZV, which could see thunder
after 00z Monday, and PIT, which may see remnant light showers
closer to dawn Monday.
.OUTLOOK....
A series of shortwaves will provide varying rain chances
through the middle of the week. While VFR is likely to be the
predominant flight category through this timeframe, periods of
heavier rain and/or patchy morning stratocu may result in MVFR
restrictions.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...MLB
NEAR TERM...WM
SHORT TERM...MLB
LONG TERM...Hefferan
AVIATION...Rackley
Source: PBZ issues Area Forecast Discussion (AFD) at Sep 21, 1:39 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202509210539-KPBZ-FXUS61-AFDPBZ)
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