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FXUS61 KPBZ 172302
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
702 PM EDT Sun Aug 17 2025

.SYNOPSIS...
Dry conditions are expected overnight through Monday as a more
seasonable and less humid airmass filters in from the north.
Outside of mid week low probability shower and thunderstorm
chances, the region is favored to be dry into next weekend with
temperature trending back above normal.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:

- Cooler air filtering in from the north will create periods of
  partly to mostly cloudy skies overnight.
---------------------------------------------------------------

High pressure will build southward as its center shifts toward
New England overnight, ushering in a slightly cooler airmass and
northerly wind. Lingering heating plus cold advection in
northwest PA may allow for an isolated rain shower prior to
10pm, otherwise subsidence favors dry weather.

The cool advection may result in scattered to broken stratocu
that may make it difficult for fog development despite lingering
near surface moisture (especially south of Pittsburgh). Look for
dry advection to erode that stratocu deck from the NE to the SW
during the dawn hours.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:
- "Coolest" day of the week is Monday
- Needed rainfall could occur Tuesday / Wednesday
----------------------------------------------------------------

There will be intervals of smoke aloft early this week with an
uptick in wildfire reports out west and in Canada.  We do not
anticipate any impacts at the surface given projections of
concentration and looking upstream states with no air quality
statements ongoing.

As we remain in a dry stretch this August, the forecast trend is
following suit for this time frame.  Despite a weakening shortwave
trough passing through Tuesday night into Wednesday, southeast wind
and downward vertical motion on the west side of Hurricane Erin
should keep the column dry enough that precip coverage won`t be
much if any at all. This is evident in the pop 12 hour profile
from the NBM with a shadow effect across northern WV and through
most of western PA Tuesday and Tuesday night. Values are
highest where we normally would expect with this low level wind
regime across eastern parts of Tucker and Preston counties north
into eastern sections of Indiana and Jefferson. Again, a
wetting rain might be tough to come by if a shower does form
given probs of of tenth of an inch or greater is around 30%
Wednesday night into Thursday and mainly in the mountains.

Temperatures after a seasonable Monday with values ranging from
the upper 70s to lower 80s, climb between 2-4F areawide Tuesday
and hover there the remainder of the short term. Humidity will
be on the increase as overnight lows bottom out in the lower to
mid 60s. You can see this in the PWAT profiles as we start out
Monday with values less than an inch /in some cases 0.8" over
northern PA/, but they quickly rebound to 1.5" Tuesday and
Wednesday. The plume of the real muggy air will stay west of our
region.

Confidence is high of no severe thunderstorm or flash flood threat
through mid week.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
KEY MESSAGES:
- More dry days on tap
- Temperatures above average
-------------------------------------------------------------------

Overall the cluster analysis illustrates good agreement in the long
wave pattern dominated by a mid level anticyclone in the southwest
and a transitory trough moving across southern Canada into the
northern United States by next weekend. Where things become less
certain is with the amplification of the aforementioned mid
level trough when it reaches the Great Lakes by next weekend.
This doesn`t have an impact on us with respect to precipitation
chances until day 6 and 7 of the forecast.

Trends continue to be drier during the late week window as the
result of subsidence on the west side of Hurricane Erin and the
baroclinic zone being well to our south in the heart of Dixie.
Elevated heat source will be the primary trigger for showers and
storms during peak heating hours. NBM 25-50th percentile precip
numbers for Thursday and Friday are zilch, while the mean
remains at a few hundredths. Will continue to keep these numbers
on the downward trend with values equating to slight chance to
at most chance verbiage in text forecasts.

The good news is that it doesn`t appear we will be adding to our
tally of 90F days at any of our climate sites.  The probability of
exceeding 89F for the long term is 10% or less.  Meanwhile, our air
conditioners will get a break at night as well given lower to mid
60s will be common.  We are in the single digit percentages of
seeing overnight lows stay warmer than 70F at any of our six climate
locations.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Post-frontal cool advection will promote waves of gradually
lowering stratocu decks that trend toward MVFR between 02z-12z.
Dry advection within the boundary layer may cause fluctuations
in cloud coverage between BKN and SCT that is not captured
within TAFs. Presence of near-surface moisture and a trend
toward light northerly wind under high pressure normally would
favor areas of fog, especially within river valleys. However,
the aforementioned strato decks are likely to hamper strong
radiational cooling necessary for IFR or lower fog.

Confidence is high in NE to SW erosion of the stratocu deck
between 08z-14z as subsidence/dry advection filters in. Dry
weather is then favored for the rest of the day as wind veers to
the ENE with occasional afternoon gusts to 15kts.

Outlook...
VFR weather likely through Tuesday before a likely weakening
upper trough approaches from the northwest to offer elevated
shower/thunderstorm chances midweek. Ensembles strongly favor
high pressure and dry weather to end the week.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...McMullen
LONG TERM...McMullen
AVIATION...Frazier