PBZ issues Area Forecast Discussion (AFD) at Sep 4, 1:56 PM EDT491
FXUS61 KPBZ 041756
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
156 PM EDT Thu Sep 4 2025
.SYNOPSIS...
Showers and isolated thunderstorms are expected today with a
passing cold front. Fog expected overnight. A second cold front
may return isolated thunderstorm late tomorrow evening. Cooler
conditions are expected over the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Showers and localized thunderstorms this afternoon/evening
- Gusty conditions may occur with showers/storms
- Fog expected tonight
---------------------------------------------------------------
A cold front is currently situated between Pittsburgh and
Cleveland this afternoon. With pre-frontal showers this morning
and heavy cloud coverage, the environment is currently
unfavorable for strong to severe storms for a large portion of
our area. If an isolated storm does develop, it would likely be
southeast of Pittsburgh or near the Laurel Highlands in the next
4 hours.
After dark, probability of thunderstorms rapidly decreases with
the loss of surface heating and the front stalling near the
ridges.
After midnight, the potential for dense fog increases with light
winds at the surface and boundary layer saturation. The most
likely areas that will be impacted by fog will be north of
Pittsburgh and in the vicinity of the stationary front.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Dry and seasonable weather favored Friday with increasing rain
chances in the evening
- Rain likely Saturday with near record low maximum temperature
----------------------------------------------------------------
The upper level pattern will experience a quick pivot back to
southwesterly flow ahead of the next deep shortwave rounding
through the broader Great Lakes trough. Modest warm advection
and initially sunnier skies are likely to aid temperature
returning near the daily average high. Subsidence ahead of the
approaching mid-level jet also will aid in Friday initially
starting dry.
Models favor the approach and passage of a fairly potent cold
front between late Friday afternoon into early Saturday morning
as the upper trough axis deepens over the Lower Ohio River
Valley. Variability continues to exist in timing of the mid-
level jet aided ascent and the surface front, of which each may
influence onset of precipitation and areas of more focus rain.
Regardless, warm air aloft is highly likely to mute severe
concerns despite strong shear before the cold front passages
ends any surface based buoyancy. The bulk of the event then will
be waves of stratiform rain overnight Friday into Saturday until
the upper trough axis more closely inches east and dry-slotting
plus lift shift accordingly, end precipitation west to east.
The combination of excessive cloud cover, rain, and near surface
cold advection Saturday means area high temperature is likely
to fall within the top 10 lowest maximums on record for area
climate sites and the coldest maximum temperature readings for
September 6th since 2011. Specifically for Pittsburgh's climate,
current modeling suggests a 10% probability of the high
temperature tying the record low maximum of 60 degrees set in
1924.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- Dry, but seasonably cool weather, is likely Sunday and Monday
before a return to near-normal temperature mid-week
- A lake enhanced shower north of Pittsburgh can't be ruled out
Sunday afternoon
-------------------------------------------------------------------
Ensemble means favor the transition of the deep upper trough
axis west to east through the region Sunday that portends to
gradual height rises within NW flow to start the next work week.
The combination of residual cold advection and cold air aloft
will keep temperature readings well below normal Sunday with a
non-zero chance for afternoon lake enhanced showers north of
Pittsburgh; global modeling may be underselling this potential
given lower resolution attempting to capture lake dynamics.
Surface high pressure is likely to develop over the area Monday
then transition east by midweek to aid in promoting dry weather
while subtle height rises favor rising temperature. Long range
outlooks are more varied beyond Tuesday due to variance in the
amplitude/depth of the next upper trough and the influences of
low pressure movement along the west coast. The key is that
cluster analysis suggests the more plausible scenarios are
unlikely to feature stark temperature changes and/or be
conducive to hazardous weather.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Areas of showers and scattered thunderstorms are expected
through the afternoon with the approach and passage of a cold
front. Instability has been limited with cloud cover and
showers. Lowered the TEMPO for thunderstorms to Prob30s for most
airports through the afternoon. MVFR to IFR conditions are
expected with reduced cigs and vsby ahead of the front.
Improvement to mainly VFR is expected after FROPA late this
afternoon into this evening, before conditions deteriorate to
IFR again overnight as stratus and fog develops with low level
moisture in place. Stratus should scatter out Friday morning
.OUTLOOK....
Low cigs are possible into Friday morning with low level
moisture in place. Additional showers and thunderstorms are
likely, late Friday into Saturday with a crossing reinforcing
cold front. Mainly VFR is then expected through Tuesday, though
a crossing upper trough and cold air aloft could lead to cig
restrictions N of PIT Sunday into Monday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...WM
Source:
PBZ issues Area Forecast Discussion (AFD) at Sep 4, 1:56 PM EDT---------------
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