064
FXUS61 KPBZ 211751
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1251 PM EST Fri Nov 21 2025

.SYNOPSIS...
Probability of rain increases late this evening and continues
into early Saturday. Mild conditions are likely this weekend and
into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Patchy fog and drizzle continues through this afternoon
- Probability of rain increases after sunset, mainly south of I-80

---------------------------------------------------------------

An area of low pressure currently centered near the Missouri/Kansas
border drifts eastward across the Tennessee Valley this evening and
tonight. A stationary front currently extending eastward from this
surface low will drift north slightly, encroaching on (but not quite
reaching) the Mason Dixon. While the track of the surface low and
its attendant boundary likely remain to our south, its closer
proximity will allow overrunning-forced rain showers to spread
across the area from southwest to northeast, starting around or
shortly after sunset and lasting through the night. Overall rain
rates and amounts will be light for most of the area. Mean 24-hr QPF
on the latest HREF shows less than a quarter inch of rainfall north
of I-70 and less than a tenth of an inch along I-80. Higher rainfall
amounts are possible south of I-70 where occasional moderate rain
rates are possible as the surface low makes its closest pass.
However, even down there the latest ensemble mean 24-hr QPF values
range from 0.25 to 0.5 inches and the 75th/90th percentiles only
show an additional one or two tenths of an inch. Therefore, flooding
concerns (both flash and river) remain low even in those areas that
see higher totals , with a light to occasionally moderate steady,
soaking rain the more likely outcome.

Due to dense cloud cover and rainfall overnight, expect temperatures
to remain steady in the low to mid 40s near and south of Pittsburgh,
while lows along/north of I-80 dip to the mid to upper 30s as those
areas remain on the periphery of dense cloud cover and rain.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Dry for the vast majority this weekend with seasonable
  temperatures
- Weak trough may bring very light precip amounts north of I-80
  on Sunday
----------------------------------------------------------------

The low makes its exit Saturday morning and returns dry weather for
most of the day, though some orographically forced showers may
linger in the ridges into the early afternoon as the shortwave will
lag behind the low and complete its passage by afternoon. Point
soundings in the higher elevations suggest steepened low level lapse
rates with marginal 925-850 mb cold advection and enough lingering
boundary layer moisture within the near dry adiabatic profiles to
support some light sprinkles/drizzle. Dry air eventually wins out
there too and clouds will erode by afternoon allowing some sun to
peek through to close out the day.

Wind will flip northerly behind the departing system as surface high
pressure builds and advect lower dew points into the area which
should finally preclude fog development, though coupled with
clearer skies, will allow for overnight lows to fall at or just
below normal.

A weak surface and mid level trough will slide by to our north on
Sunday. Moisture in our area, especially of I-80, will be scarce,
with increasing subsidence and the best surface and mid-level
forcing off to our north. Depending how quickly the surface high
builds, we could sneak a few very light showers into far northern
parts of our area. Surface temperatures will likely be warm enough
to support rain with perhaps some graupel mixing in with steep low
level lapse rates and ELs pushing up to around -5C. Anything that
falls will be light; NBM 90th percentile QPF is a few hundredths of
an inch.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Dry Monday with above normal temperatures
- Active pattern returns by mid-week with passing low pressure
  bringing rain for most
- Some lake effect snow is possible by week`s end
-------------------------------------------------------------------

Transient ridging will move through locally on Monday with high
confidence, and latest ensembles have come into better agreement
with departure of the weekend trough by Monday morning with subtle
mid-level height differences locally. Some subtle temperature
differences arise, but even a cooler solution still supports highs
into the low 50s and an overall comfortable day for late November
despite increasing clouds late.

The dry trend will be short lived as ensembles all favor another
ejecting mid-level trough and surface low through the central US by
Tuesday. The pattern is high confidence, but the details remain low
confidence with timing and depth of the responsible trough as some
members support a closed mid level low with others a fast open wave.
Associated low pressure likely passes through our area sometime
Tuesday-Wednesday and returns precip chances with then possible wrap
around precip continuing into the end of the week, but the low`s
track and timing is very uncertain lending low confidence impacts
locally. The likely track of the low will be to our north, keeping
us on the warm side, but how quickly it turns north will be
dependent on the strength of a surface high to our east. In any
scenario, not a whole lot of liquid is expected with it. Low end QPF
is around a tenth of an inch with high end closer to three quarters
of an inch, so even if the system can maximize, total amounts over a
48 hour period will likely remain below an inch.

Will then have to monitor what happens on the back side of the
departing low with regard to cold air and snow potential. What seems
most likely is that the lake effect machine would turn on with cold
air intrusion over the lakes, though the exact degree of cold air,
prevailing wind direction, and forcing still remains a question as
snow showers/bands could set up with a west-east orientation and
spare most of our area or a northwest to southeast orientation and
bring more impact locally. Entirely too much ensemble spread exists
to try to dive into specifics yet aside from following synoptic
scale trends. Bottom line for now is to monitor the forecast for
that timeframe into the coming week. If your post-Thanksgiving
travel plans take you along Interstate 90 from Cleveland to Buffalo,
snow is likely a bit higher probability in that corridor, so
reference the CLE and BUF offices` forecasts for the best
information.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- IFR restrictions and patchy drizzle continue this afternoon
- Rain overspreads area from southwest to northeast after 00Z
  and lasts through tonight.
- VFR returns late Saturday or early Sunday and lasts through
  Monday.

---------------------------------------------------------------

A mix of LIFR/IFR conditions are ongoing to start the period at most
area terminals. Fog is generally dissipating, but the area remains
socked in under low stratus with cigs hovering in the 300-500 ft AGL
range at most locations. Expect only minor additional improvement
through the rest of the afternoon before rain overspreads the area
from southwest to northeast after 00Z. Rain and associated
restrictions prevail overnight at all terminals except DUJ/FKL which
may end up being the northern periphery of the rain, so left PROB30
in those TAFs for now. Dry north-northwest flow sets up Saturday
morning, which will help gradually erode fog and stratus from
northwest to southeast following the departure of the rain.

Outlook... Improvement back to VFR is likely during the day Saturday
as dry air filters in from the north-northwest. MGW may be the final
terminal to see improvement, possibly as late as post-sunset
Saturday night. There is high confidence of VFR under the influence
of high pressure beginning Sunday morning until the next low
pressure system arrives near Tuesday.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Cermak
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...Cermak