PBZ issues Area Forecast Discussion (AFD) at Sep 26, 7:48 PM EDT195
FXUS61 KPBZ 262348
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
748 PM EDT Fri Sep 26 2025
.SYNOPSIS...
Mostly dry Friday with fog possible again early Saturday. Rain
chances ramp back up south and east of Pittsburgh on Saturday
with passing low pressure. Dry and unseasonable warm on Sunday
ahead of a more uncertain pattern headed into next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
KEY MESSAGES:
- Mostly dry, a few showers over the ridges
- Mild overnight with areas of fog primarily north of Pittsburgh
---------------------------------------------------------------
With the exit of a mid-level shortwave, modest height rises and weak
surface high pressure will provide a mostly dry day today as drier
air evident on low and mid level water vapor loops advects in.
Enough boundary layer moisture should support a transition from
lingering stratus to diurnal cu this afternoon as our convective
temperature from the 12z sounding of 71F is reached. A few
showers/some drizzle may develop across the WV/PA terrain where
light northwest flow provides meager upslope enhancement within
a shallow profile of low-level moisture.
The loss of the cu deck tonight will be quickly replaced by
increasing clouds from the south as weak low pressure develops
across the Carolinas. Dry weather is likely to prevail locally until
Saturday morning. Dew points are progged to be a few degrees lower
than Thursday night, but still see some signal for fog development
again tonight. Probability for <0.25 miles is elevated at 50-60%
north of Pittsburgh where the clouds will take the longest to reach
and very light to calm wind will allow for most efficient
radiational cooling. Some patches of fog in sheltered areas may
develop farther south, but don't expect the coverage and density
that we saw Friday morning.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Low pressure returns rain chances south and east of Pittsburgh
- Dry and warm on Sunday
----------------------------------------------------------------
A digging trough across the southeast CONUS will support the
development of weak low pressure across the Carolinas and slowly
steer it up the East Coast. Ensembles offer little variability in
the upper level pattern, but do suggest slight differences in
surface low track which will determine how far north and west the
QPF footprint extends. Rain chances locally ramp up just after
sunrise Saturday morning across northern WV and spread north and
east through the day. Current consensus is that the highest rain
chances and heaviest amounts are to the east of Pittsburgh
coincident with best forcing from the low and upper jet support. A
sharp gradient in PWAT is likely to bisect the area with lower
amounts north and west and higher to the south and east. Clusters
dominated by the ECMWFE do suggest a slight northwestward jog in the
low which could raise PoPs a bit farther northwest, but that
solution is lower probability at this time. Current probability for
>0.50" reaches as high as ~50% in northern WV and quickly tapers off
into southwest PA, and there sits about a 20-40% chance of >0.75".
Dew points will be on the rise through the day and temperatures are
still likely to reach the 70s across the area (some 80s
possible in NW PA/eastern OH on the fringes of the cloud
shield), so it'll feel a bit more sticky out there as well.
Areas of fog are possible Saturday night, though where the rain
falls during the day, clouds are less likely to clear out, so
lingering surface moisture there may manifest more as stratus than
fog.
Ensembles then support the upper low cutting off from the flow on
Sunday as surface high pressure builds across the Great Lakes. This
should keep us dry to close out the weekend and warmer than Saturday
with less cloud cover. It'll be unseasonably warm with a 70+% chance
of >80F for highs. Dew points should mix out some, but it could
still feel more like the mid 80s by the afternoon.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:
- Much greater uncertainty for the beginning of next week dependent
on tropical low development and track
-------------------------------------------------------------------
Eyes turn to the Atlantic at the beginning of next week with
potential tropical development offshore of the Carolinas. Two areas
of low pressure are favored to develop with one disturbance moving
along the coast out of the Caribbean and Humberto remaining
offshore. A complicated pattern evolves with how all of this may
play out with numerous solutions still in play. The bottom line
right now is that notable impact to our area is not expected.
All ensembles support high pressure sinking south through Ontario by
mid-week albeit with slight differences in strength and timing. One
possible solution is that the developing disturbance gets absorbed
by the southeast CONUS trough/cut off low, very slowly meanders
around the coast, and brings increased cloud coverage areawide with
some rain to the southern part of our area for the beginning of the
week. It's also possible that the high builds in quicker and
stronger and is able to shunt the rain shield to our south and east.
This solution provides a dry and warmer forecast locally. The
uncertainty is represented well by NBM MaxT spread Tuesday and
Wednesday being as high as 10 degrees between the 25th/75th
percentiles (as warm as the upper 70s or as cool as the upper 60s).
The current forecast essentially depicts the center of the road
among possible solutions which is likely unrepresentative of the
actual outcome as it's more likely that we'll go down one path or
the other. Once more answers become clear, temperature and
precipitation chances will trend up/down, but for now given the
uncertainty, have held with NBM which introduces mentionable PoPs
south of Pittsburgh Monday through Wednesday.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions are forecast through the evening and most of the
overnight period at most TAF sites, with mainly high clouds.
Some patchy fog development is expected late, but it should not
be nearly as widespread as this morning. HREF probabilities of
IFR/LIFR visibility peak at FKL/DUJ in the 06Z to 12Z period,
which makes sense given that clouds should be thinnest at these
terminals. Any fog should dissipate by mid-morning.
Cloud clover continues to increase Saturday from the south as a
weak low moves up the East Coast. Ceilings will likely drop into
the MVFR range at MGW and LBE during the late morning and early
afternoon, with a shower or two possible at these sites as well
(PROB30 used). Ceilings at other terminals are most likely to
remain in the VFR range, with a smaller shower chance.
.OUTLOOK....
Ceiling restrictions may linger into Saturday night or Sunday to
the southeast of PIT. Otherwise, VFR is expected through early
next week under high pressure. Restriction potential returns
southeast of PIT Tuesday ahead of a coastal low.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...CL/Cermak
Source:
PBZ issues Area Forecast Discussion (AFD) at Sep 26, 7:48 PM EDT---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
