PBZ issues Area Forecast Discussion (AFD) at Sep 21, 4:19 AM EDT544
FXUS61 KPBZ 210819
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
419 AM EDT Sun Sep 21 2025
.SYNOPSIS...
Above normal temperatures will continue while shower and storm
chances increase later today and into next week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Largely dry conditions today
- Continued above normal temperatures
---------------------------------------------------------------
Patchy fog is possible where rain occurred yesterday and sees
partial clearing, but otherwise, most spots will see at least
scattered cloud coverage. Low temperatures will bottom out 5 to
10 degrees above average with the increased cloud coverage with
a crossing shortwave. Latest CAMs show very limited convective
activity through the afternoon, and model soundings show warmer
air in the lower levels keeping a lid on things.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
KEY MESSAGES:
- Rain chances increase tonight with a warm front
----------------------------------------------------------------
Tonight the area will see increasing rain chances as a warm
front crosses the region, particularly over eastern Ohio
counties where latest ensemble guidance shows up to 50% PoPs.
Coverage and organization this evening 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
joint probabilities for >1000 J/kg SBCAPE and 25 knots of 0-6km
bulk shear reaches around 25-30% which could point toward a low
end wind threat, though latest CAMs suggest arrival time around
sunset in our eastern Ohio counties which would not necessarily
be the most ideal time, and latest CSU-MLP guidance and CIPS
analog guidance do not show a wind threat for today.
SPC has maintained a Marginal Risk (1/5) for damaging wind for
eastern Ohio, 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. On Monday, the Day 2 Marginal was expanded east
almost to the ridges as there should be better shear to organize
convection. Still, the threat will primarily be damaging winds.
&&
.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, 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 increased cloud coverage.
&&
.AVIATION /08Z 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...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...88
AVIATION...Rackley
Source:
PBZ issues Area Forecast Discussion (AFD) at Sep 21, 4:19 AM EDT---------------
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