Tarrs, Pennsylvania Weather Forecast Discussion

752
FXUS61 KPBZ 251741
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
141 PM EDT Thu Sep 25 2025
.SYNOPSIS...
There are diminishing rain chances through tonight as a slow
moving system begins to exit east of the region. Dry and
seasonably warm conditions are favored for most of the region
this weekend save for lower probability showers southeast of
Pittsburgh Saturday.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Diminishing rain chances, and associated flood risk, through
  tonight with exiting shortwave
- Stagnant moist environment may be conducive to overnight fog
---------------------------------------------------------------
The main 700mb shortwave has begun lifting northeast toward New
England as the upper level trough continues to sag southeast.
Diminishing of areal coverage of rain showers as well as
rainfall rates has already begun as mesoanalysis shows drier air
working in from the west, evidenced by falling PWAT values.
Isolated to scattered showers may remain into the overnight
period (aft 00z), however, due to weak lift produced by the
crossing of the upper trough axis. Though frontogenesis could
cause these isolated showers to produce narrow bands of heavier
rain, falling PWATs and short duration are likely to keep
flooding concerns low.
Hi-res modeling shows variation in the degree of west to east
cloud clearing overnight behind the trough axis, creating
uncertainty in the degree of fog development for the region.
Given the abundance of boundary-layer moisture with little to no
air movement, conditions are likely to favor at least patchy fog
with the potential for more widespread dense fog conditions
(hi-res modeling suggests 50-60% probability for dense fog west
of Pittsburgh). If confidence increase in widespread dense fog
conditions, a Dense Fog Advisory may be needed.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Drier, warmer on Friday
- Potential moisture influx Saturday could lead to showers
  southeast of Pittsburgh
----------------------------------------------------------------
Subsidence and weak dry air intrusion will support drier
conditions Friday as longer periods of insolation lift area
temperature near to slightly above average. Though precipitation
is unlikely, there may be enough upslope flow along the higher
terrain combined with diurnal heating to generate a very brief
shower/sprinkle.
Most of the region will remain dry Saturday under the influence
of high pressure with weak flow aloft. A cut off trough sitting
over the Carolinas may begin to negatively tilt enough to draw
moisture from a coastal low northward toward the Mason-Dixon
line. This slight moisture increase with diurnal heating creates
lower probability shower chances southeast of Pittsburgh
Saturday. Lightning can`t be ruled out, but ensemble means of
SBCAPE near 100 J/kg and warm height layers suggest occurrence
is very unlikely.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Larger variance period that will be predicated on coastal low
  and tropical movement along the Atlantic Coast
------------------------------------------------------------------
Ensemble cluster analysis shows forecast outcomes to begin
diverging notably Sunday into early next week due to large
variance in the development/path of a Carolina coastal low AS
WELL AS whichever way tropical storm develops occurs in the
western Atlantic. At this time, the two more likely scenarios
are: the low/southeast trough remains stationary and draws rain
showers to the southeast portion of the CWA while increased
cloud cover limits diurnal heating; strong ridging builds over
the Great Lakes that shunts tropical action south/east and
maintains dry weather with temperature trending well above
normal.
The current forecast more straddles these two scenarios so there
likely will be changes in the coming days to trend both
temperature/precipitation chances up/down if and when model
output begins to converge on the most likely solution.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
The heaviest and most widespread rainfall has moved out of the
area, with scattered light showers and generally MVFR (a few
lingering spots of IFR) restrictions prevailing through the
remainder of this afternoon. A few terminals could sneak to VFR
for brief periods this evening, but a widespread degradation of
conditions is expected overnight as low stratus and fog settle
back into the region.
Latest hi-res ensembles show 60-80% probabilities for ceilings
below 1000ft across the lowlands and 80-100% along the ridges.
Additionally, they suggest 40-60% probabilities for visibilities
below a mile primarily across eastern Ohio and the northern WV
panhandle, with lower probabilities farther east towards the
ridges where low stratus appears to be favored instead.
Gradual improvement back to MVFR is expected Friday morning.
.OUTLOOK....
VFR returns under building high pressure Friday afternoon.
Restrictions and showers are possible, mainly S-E of PIT,
Saturday and Sunday with a crossing upper trough. VFR is
expected Monday under high pressure.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Cermak

NWS PBZ Office Area Forecast Discussion