383
FXUS61 KPBZ 200601
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
101 AM EST Thu Nov 20 2025

.SYNOPSIS...
Dry weather continues today under high pressure. Rain chances
increase early Friday before decreasing Saturday morning. The
highest rain amounts, one half of an inch to one inch will be
south of Pittsburgh. Seasonable temperatures are expected through
the weekend.
&&

.NEAR TERM /THROUGH TONIGHT/...
- Fog, freezing fog (north of PGH), and low clouds early this AM
- Dry and cloudy, with seasonable temperatures through the day
---------------------------------------------------------------

Saturated low levels and light wind with surface high pressure
centered over the region is resulting in a fairly good morning
for fog development. Despite fairly widespread low stratus and
upper level clouds streaming across the region PGH and north,
fog has developed across the region, enough so to warrant a
Dense Fog Advisory that has been issued and is valid through
9AM. Areas north of PGH are under a Freezing Fog Advisory as
temperatures <32F and visibilities <1/4mi have been observed,
and are likely to persist through the early morning. As far as
impacts, other than visibility under 1/4 mi in places, areas
north of PGH may see a light glaze on elevated surfaces,
bridges, and overpasses. Looking at latest METRo road
temperature forecasts the window where road surface temperatures
could be below freezing looks to be in between 4AM and 8AM this
morning.

Fog should diminish mid-morning with increased mixing, but low
stratus is likely through the day as low level moisture remains
trapped under a strong inversion. Surface high pressure
centered over the northeastern U.S. and ridging extending
southwestward across New York and into western PA will maintain
dry and cloudy conditions, with seasonable temperatures during
the day.
Overnight will be largely dry, but rain chances will begin to
increase early in the morning as low pressure approaches from
the west.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
KEY MESSAGES:

- Rain returns on Friday
- Near to above seasonable temperatures
----------------------------------------------------------------

A surface low will push through the Midwest and Ohio Valley
regions early Friday, resulting in widespread rain chances
during the afternoon and evening, with the highest chances PGH
and south. Temperatures will rise to 5-10 degrees above seasonal
levels. Unfortunately, there is still a fair bit of uncertainty
regarding exact rainfall amounts with this system, though there
is a strong signal among guidance that (relatively speaking)
the highest amounts will fall along and south of the I-70
corridor. The latest NBM 10th/90th percentiles suggest anywhere
from zero rainfall across the entire area to as much as 1.25"
(locally 1.5" in northern WV), which isn`t very helpful. Even
the interquartile spread is 0.5" to 1.0" inches in most places,
with the 25th/75th percentiles ranging from zero to 0.6" north
of I-70 and from 0.10" to 1.15" south.

Regardless, this would be a long-duration stratiform and steady rain
with rates remaining light to occasionally moderate. Thus, there is
little concern for flash flooding at this time and most area rivers
are expected to see only minor rises, if any.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
KEY MESSAGES:

- Near to above seasonable temperatures continue
- Rain tapers Saturday, followed by dry conditions on Sunday
- Unsettled weather returns early to middle next week
-------------------------------------------------------------------

The upper shortwave trough and surface low mentioned in the short
term discussion will move across the area and depart to the east
Saturday morning. A few light rain showers or sprinkles may linger
into Saturday afternoon (best chances along the ridges), but for the
most part a dry forecast returns through at least Sunday.

By Monday, numerical guidance hints at another upper trough ejecting
eastward from the Rockies across the Great Plains, setting us up for
another low pressure system to move into the Ohio Valley region
during the early to middle part of next week. There is still too
much uncertainty to begin narrowing down any specifics regarding
precipitation types, amounts, or timing. The takeaway here is that,
at this time, the weather pattern next week appears unsettled.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Stout low level moisture and a lack of SFC flow allows the
forecast period begins with widespread dense fog bringing VIS
down to 1/4SM at many ports. Those not at this level are
expected to trend that way over the coming hours. Eastern ports
(DUJ/LBE) have found themselves in FZFG with temps below 32. FKL
currently sits near the edge of the expanding fog but is
expected to experience FZFG early this morning. With little
change in conditions overnight, this fog is expected to remain
locked in until at least 14z, where we may begin to see a little
mixing out starting across the region.

It is tough to imagine we make large gains in CIGs through the
morning hours and only marginal improvements are forecast
through midday. Beyond that it becomes more difficult to pin
down where our CIGs will trend. Some high-res models are rather
optimistic with a brief period of high MVFR/low VFR CIGs this
afternoon, but with how poorly they have handled the last 24
hours it is difficult to put much stock in this solution. The
more likely scenario at this time is that CIGs rise marginally
in the afternoon, returning to more widespread low MVFR before
another eventual reduction in CIGs again Thursday night.

Winds remain largely light through the TAF period with a minor
Nerly component early before a swing to the SW during the
afternoon.

Outlook... Chances of restrictions and rain increase with a
passing disturbance on Friday. The area could dry out as early
as Saturday morning, after which a gradual scattering of clouds
could be seen.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 9 AM EST this morning for PAZ020-021-
     029-031-075-076.
     Freezing Fog Advisory until 9 AM EST this morning for
     PAZ007>009-013>016-022-073-074-077-078.
OH...Dense Fog Advisory until 9 AM EST this morning for OHZ049-050-
     057>059-068-069.
WV...Dense Fog Advisory until 9 AM EST this morning for WVZ001>004-
     012-021-509>514.

&&

$$

SYNOPSIS...88
NEAR TERM...88
SHORT TERM...Cermak/88
LONG TERM...Cermak
AVIATION...AK