Clark Run Trail, Pennsylvania Weather Forecast Discussion

640
FXUS61 KPBZ 061753
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
153 PM EDT Mon Oct 6 2025
.SYNOPSIS...
High pressure centered east of the coast will maintain dry and
warm conditions today. A passing cold front returns rain on
Tuesday, followed by dry and cooler conditions the remainder of
the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
KEY MESSAGES:
- Dry and warm Monday
- A soaking rain arrives on Tuesday with a high probability
  for at least a half an inch areawide
---------------------------------------------------------------
Another day of mostly sunny skies and above average temperatures as
ridging remains the dominant feature. With minimal change to
heights/thickness values, temperatures will be very similar to what
was observed Sunday, between 10 to 15 degrees above normal. Cloud
coverage will be on the increase tonight as upper level moisture
works in ahead of a passing cold front on Tuesday. With southerly
flow promoting warm advection overnight, lows will only dip into the
upper 50s/low 60s. Some very light, warm advection driven rain
showers may encroach on eastern OH/far western PA in the latter half
of the overnight hours, but with plenty of near-surface dry air to
battle, any that makes it to the ground will be light.
Deep layer southerly flow continues pumping in increased moisture
into the morning hours on Tuesday. Expect that early morning
scattered showers will preface more widespread, steady rain by the
late morning as increased warm advection/isentropic ascent and
convergence along and ahead of a cold front increase forcing. By
this point, PWAT values are progged to reach 1.5-1.75" which is
above the 95th percentile of climatology. Given the ongoing warm
advection, deep layer profiles will be well-saturated and near moist
adiabatic. Thus, it`ll be tough to get much instability going, but
warm rain processes with warm cloud layer depth to around 13kft
should still allow for efficient rainfall. The best overlap of
forcing and moisture will be in the late morning through the
evening, so that should be our window for the steadiest, widespread
rain.
Subsequent NBM runs continue bumping up storm total rainfall
amounts; probability of >0.5" is at 90+% areawide and probability of
>1" between 50-70%. Even non-zero probability for >2" now reaches as
high as about 20-30% south of I-70 and 10-20% in strips farther
north. The HREF and REFS both suggest localized totals as high as 2"
possible as well in areas where heavier rain trains. Bumping up the
neighborhood radius in both ensembles (accounts for spatial
uncertainty) sees these probs jump as high as 30-50%, suggesting the
chance is there, but the exact location remains more questionable
and these amounts would be highly localized. Don`t see a widespread
flooding threat as this should all fall on a longer timescale with
the chance of 1"/hour rates very low and dry antecedent conditions
precluding such a threat. Some isolated issues in poor drainage
areas are possible with falling leaves. Wouldn`t be surprised to see
a few rumbles of thunder, but the poor lapse rates and very low
instability lends a low probability.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
KEY MESSAGES:
- Decreasing rain chances Tuesday night into Wednesday morning
- Cooler, drier air mass for Wednesday/Thursday offering
  potential for morning frost
----------------------------------------------------------------
Rain will end from west to east with frontal passage on Tuesday
night. Lingering low-level moisture and cold advection will
likely result in a stratocu deck, but increasing dry air should
erode the clouds by Wednesday morning and elevated wind/lowering
dew points should preclude fog development.
High pressure will quickly filter in behind the exiting front
and offer a notable airmass change for Wednesday and Thursday.
The residual pressure gradient and diurnal mixing Wednesday may
generate 20 to 30mph gusts during the afternoon before tapering
off Wednesday night.
The cooler, drier air mass will result in afternoon heights
near (Wednesday) to below average (Thursday) despite mostly
sunny skies. This change also creates potential frost and
localized freeze concerns for low temperature Thursday/Friday as
cooler air plus radiational cooling likely creates lows in the
30s and 40s. The key limiting factor to any freezing temperature
or frost will be potential for elevated northerly winds from
the residual pressure gradient Thursday morning (and warmer
downslope east wind Friday morning).
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Dry weather favored through the weekend, though pattern
  variability exists
-------------------------------------------------------------------
There is high confidence in strong surface high pressure
positioning over the New England Friday into the weekend as the
upper Ohio River Valley sits underneath a weak, saggy trough.
This will promote dry weather and gradual warming to about 5
degrees above the daily average through the period.
There remains some uncertainty in this as a potential
developing/deepening coastal low forms near the mid Atlantic and
has potential for inland movement. If confidence in this
scenario exists, an upward trend in precipitation chances along
with a downward trend to temperature (due to increased cloud
cover) for eastern zones could occur.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR will continue through the day today under high pressure centered
off of the Mid-Atlantic coast. Southwest flow on the western side of
the high should result in some moisture return across eastern Ohio
and northwest Pennsylvania this afternoon where some FEW/SCT
cumulus/stratocu is expected. Otherwise, expect an increase in mid
level clouds, mainly this evening, ahead of an approaching cold
front.
Restrictions will begin to creep into the area from the west Tuesday
morning as rain arrives. A passing batch of showers is possible
overnight for ZZV, HLG, BVI, FKL, and possibly PIT, but this isn`t
well depicted among all guidance, so have just introduced PROB30s
for this after 06z. Most likely arrival time for the more steady
rain is around 11z for ZZV, 14z for PIT and right at the end of the
current TAF period for LBE. These could have some wiggle room toward
a slightly later arrival. Profiles suggest still very limited
moisture in the lower levels at onset, so it`s likely that ceilings
take a bit to come down as the column wet-bulbs, and we may see high
end MVFR vis restrictions in rain with still low end VFR cigs
initially. Some of the more coarse guidance is much more aggressive
with rapid onset of restrictions, but have erred more toward the
HREF depiction which suggests rain initially begins and lowers vis
and cigs subsequently come down shortly after. MVFR probability is
90+% in the rain with IFR cig potential arising at the end of the
current TAF period when the column fully saturates, so confidence in
eventual restrictions is high.
Some stratocu likely linger in the wake of the passing cold front
with low level cold advection and wind will shift to the north-
northwest. Dry air should work in behind the front Tuesday night and
gradually erode the clouds by Wednesday morning.
.OUTLOOK...
VFR is expected to gradually return Wednesday after FROPA, and
continue through Friday, as high pressure builds in.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Frazier/MLB
NEAR TERM...MLB
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...MLB

NWS PBZ Office Area Forecast Discussion