Hermitage, Pennsylvania Weather Forecast Discussion

357
FXUS61 KPBZ 221148
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
748 AM EDT Mon Sep 22 2025
.SYNOPSIS...
Above normal temperatures are expected ahead of a developing
upper level low, which may spawn increased shower and
thunderstorm chances later this afternoon and evening. This
system will be slow to exit the area, resulting in daily rain
chances through the end of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Scattered showers around through dawn
- A Marginal Risk of severe weather is possible today
---------------------------------------------------------------
The day will begin with a few showers over the area this
morning. This may impact the potential for significant
destabilization but the ensembles do show a bit of a break in
the convection by midday.
The first in a series of shortwaves amidst the gradual
development of a sagging trough (and potential cut off low) is
expected to encroach the region this afternoon and evening.
This jet-induced lift combined with a seasonably warm and moist
airmass is likely to lead to scattered to locally numerous
discrete thunderstorms that favor locations generally to the
west and north of the I-79 and I-70 interchange. Modest CAPE
(~1200 J/kg) and weak shear (around 30kts) are enough to
support a low-end damaging wind threat along with heavy rain
potential, though dry antecedent conditions and fast enough
storm-motion should stunt any flood concerns. In fact, hi-res
cams suggest a decaying line of storms this evening.
Potential for showers and thunderstorms are likely to continue
overnight Monday into Tuesday morning as the shortwave
traverses the region, ensuring most locations are likely to see
measurable rainfall.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- Cloud cover will limit the heating on Tuesday but showers and
  thunderstorms are still expected.
----------------------------------------------------------------
The increased cloud cover will limit heating on Tuesday to keep
area CAPE likely below the 1000 J/kg threshold for severe
concerns given shear will remain sub-optimal. Still a few
instances of thunderstorm wind gusts are still possible. Brief
shortwave ridging between shortwave movement likely will yield a
drier overnight period Tuesday night. By Wednesday, the cold
front has moved through the region leaving mush cooler
conditions for Wednesday. The amount of instability will be
minimal but showers will be expected through the day on
Wednesday.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
KEY MESSAGES:
- Elevated precipitation chances through Saturday
- Near average temperatures
- Mainly dry conditions return by Sunday.
------------------------------------------------------------------
A stalled trough positioned between the Great Lakes and the
Mississippi River Valley will bring the region periods of
clouds, rain chances, and near-normal temperatures through the
latter part of the week.
Ensemble guidance suggests Thursday into Friday may offer the
greatest potential for more widespread rainfall, supported by
enhanced jet dynamics tied to the trough. Increasing southwest
moisture transport will likely push PWAT values into the 1.5 to
1.7 inch range, with a deep warm cloud layer extending above
13kft. Rainfall totals from Thursday morning through Saturday
morning are expected to range from 0.4 to 0.75 inches, with
locally higher amounts (over an inch) possible, especially near
and within the ridges and south of Pittsburgh. Given dry
antecedent soils and sufficient shear to keep convective
progressive, the flood threat is considered `low`.
Afternoon high temperatures will likely hold near the mid-70s
(close to average) during this time period, while overnight lows
trend about 5 degrees above normal due to elevated dew points
and limited radiational cooling. The extended wet pattern will
take a break by Sunday as the last of the moisture exits the
area leaving high pressure to infiltrate the region.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
By 12z much of the showery activity is expected to be through
the region with lingering low MVFR CIGs to start at FKL. VFR is
expected to return region wide very shortly thereafter with
broken VFR CIGs expected through much of the day. By late
afternoon it looks possible for very spotty showers to be across
the region although potential for restrictions from this
activity is expected to be low.
A crossing shortwave is expected to help thunderstorm
development by late this afternoon in OH and this evening in
PA. Storms are expected to congeal into a line and could pose a
threat for isolated wind damage as well as periods of lowered
VIS in heavy rain. These storms have been timed out using TEMPO
groups for all but our far eastern ports (PROB30s) where the
instability available weakens and probability of impact begins
to drop.
Behind this line of showers and storms, CIGs and VIS are
expected to drop quickly with most ports sporting a 60% or
greater chance to be down to IFR by 06z Tuesday. CIGs are
expected to bottom out near the IFR/LIFR border with VIS
impacts in remaining showers and mist likely through the
overnight period.
.OUTLOOK....
Restrictions are expected to lift through the day Tuesday
giving way to general VFR. Restrictions can return with
approaching low pressure and additional rain across the area
Wednesday into Friday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Shallenberger
NEAR TERM...Shallenberger
SHORT TERM...Shallenberger
LONG TERM...Hefferan/Shallenberger
AVIATION...AK

NWS PBZ Office Area Forecast Discussion