962
FXUS61 KPBZ 150542
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1242 AM EST Sat Nov 15 2025

.SYNOPSIS...
High pressure departs tonight with dry weather through most of
tonight. Fast moving low pressure crossing the Great Lakes
tomorrow will bring increasing warmth and moisture along with
the chance of showers and gusty thunderstorms. Brisk and cooler
weather is on tap for Sunday with northwest-flow showers.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
KEY MESSAGES:

- Dry for most tonight with above normal low temperatures
- First raindrops may arrive late tonight
---------------------------------------------------------------

The stratocu layer remains thick this evening especially east of
Pittsburgh where mid-level moisture continues streaming through
in northwest flow. Meanwhile, warm advection from the 925-700 mb
layer has driven a scattered deck of lower clouds over the
remainder of the area. Doesn`t look like we`ll be able to
scatter out a whole lot tonight with warm advection continuing
overnight, but the mid-level deck should slide off to the east
with gradual height rises. Overnight lows will hold above
normal and with quite a gradient ranging from near freezing
north of I-80 to values in the mid 40s to the south of I-70.
Enough moisture/isentropic lift may exist after 06Z for the
first drops of light rain to arrive ahead of an approaching warm
front that will cross early Saturday.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
KEY MESSAGES:

- Rain chances increase Saturday afternoon and night
- Isolated thunderstorms with gusty wind are possible Saturday
  evening
- Turning blustery and colder Sunday, with showers continuing
----------------------------------------------------------------

The flattening ridge axis crosses the Upper Ohio Valley Saturday
morning, accompanied by the surface warm front. Increasing column
moisture and some modest isentropic lift may continue to fuel some
patchy light rain/showers through the morning. There also could be a
period of several hours that favor an area of advection fog,
particularly north of Pittsburgh, as suggested by HREF visibility
probabilities. This would be in spite of strengthening flow aloft,
although eventually, by midday/early afternoon, wind should become
strong enough, and temperatures warm enough, to lessen the fog
concern.

Attention then turns to the cold front which is slated to cross the
region Saturday evening. A 500mb shortwave will take on a
negative tilt as it crosses the Upper Great Lakes Saturday
afternoon and evening, helping to propel the boundary forward.
CAMs do show shower development along and ahead of the boundary,
but the potential for deep convection still remains
questionable. After weakening a bit in the morning, 0-6km bulk
shear increases into the 45 to 55 knot range during the
afternoon and evening. Instability remains the limiting factor.
A warm layer aloft remains present on model soundings, limiting
CAPE (HREF probs of 200 J/kg generally 50 percent or less from
6PM to midnight), and lapse rates aloft remain poor. Support for
lift to overcome the inhibition remains uncertain. A 250mb jet
will be nosing into the Ohio Valley on Saturday, but timing of
best upper divergence in favored quadrants is not clear. Still,
if evaporative cooling aloft can sharpen lapse rates at least on
a localized basis, some low potential for downward transport of
40-50 knot flow to the surface remains. The SPC day 2 Marginal
severe risk for wind gusts is reasonable. Away from
showers/convection, even modest mixing will allow background
wind gusts into the 20 to 25 knot range. Given the shear and
cold air aloft, some small, graupel-like hail could be possible
in a few cases as well.

Northwest-flow showers should continue behind the front through
Saturday night into Sunday, eventually becoming mainly
concentrated to areas north of US-422 thanks to lake
enhancement. 850mb temperatures falling to subzero values will
allow a mix with, and and eventual change to snow by 00Z Monday,
with any accumulation of note likely holding off until after
sunset. A still-decent surface pressure gradient and better
low- level lapse rates on Sunday should allow for more
efficient mixing, with widespread wind gusts to 30 knots. The
Laurels of course will likely reach higher peaks between 30 and
40 knots. A Wind Advisory may eventually be needed for eastern
Tucker County; NBM probabilities of max gusts greater than 45
MPH are in the 75 to 95 percent range.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
KEY MESSAGES:

- Potential lake effect snow band late Sunday into Monday in
  northwest PA
- Active weather pattern continues, favoring seasonably cool
  temperature
-------------------------------------------------------------------

By Sunday afternoon/evening, cold advection in northwest flow
plus weak vorticity advection will begin to aid development of a
lake effect band over a narrow swath of northwest PA that will
slowly taper off into Monday. The key trends both in global and
initial hi-res model runs suggest slightly cooler 850mb temps
(inching toward -8 degrees C) with subtle wind angle changes
that may create a moisture fetch from Lake Superior through Lake
Erie. If this occurs, a narrow portion of
Venango/Forest/Clarion/Jefferson Counties could see snowfall
accumulations approach/exceed warning criteria (6+) inches.
Confidence remains low without more higher-resolution data as
well as potential variances in the snow band axis, but
highlighted this region for potential snow headlines through the
day Monday.

Otherwise, cold northwest flow with high pressure to the west
will support drying conditions across the region late Sunday
into Monday as area temperature falls back below normal. Residual
pressure gradients and mixing support periods of 25-35mph gusts
through Monday in the lowlands, with potential Advisory level
gusts in the highest terrain of eastern Tucker County. Again, if
confidence increases on this occurrence, wind headlines may be
needed.

The active weather pattern continues Tuesday as lingering
troughing over the eastern CONUS sees a fast-moving embedded
shortwave dip south of the region that will create additional
precipitation chances favoring south of Pittsburgh (current
thermal profiles lends to rain with any snow struggling to
accumulate). Thereafter, long range ensemble models show
increasing variance with placement of upper ridging, suggesting
it either edges east (fostering warming trend and brief dry
period) or remains over central CONUS (maintain cool weather
with intermittent but low accumulation precipitation).

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions should prevail through sunrise, though mid/low-level
clouds will continue to thicken as the result of a crossing
disturbance and warm advection. A lingering low-level jet will
keep LLWS for ZZV through around 10z this morning.

Moisture will increase today with the crossing warm front.
Probabilities of MVFR cigs begin to spike above 80 percent
after 10Z or so, mainly south of I-70, before overspreading
other terminals during the rest of the morning. IFR vsby
probabilities are highest (above 50 percent) in the I-80
corridor from mid- morning into early afternoon. Thus, at
FKL/DUJ, prevailing IFR cigs were introduced with fog/mist and
light showers. The southern extent of these restrictions remains
a bit uncertain, and PROB30s were maintained for potential
impacts at all other terminals. Southwest wind will begin to
pick up after sunrise, with gusts to 20 knots possible. A drier
period will return for a few hours in the early afternoon in the
open warm sector ahead of an approaching cold front that will
pass late Saturday evening. Brief convection and gusty wind is
possible along/ahead of the front before rain clears and clouds
begin to lift and scatter overnight into Sunday.

Outlook...
Wind will shift to the northwest and gust to 20-25 knots
Saturday night. Lake-enhanced precipitation is expected behind
the front on Sunday with the typical scattered nature. MVFR cigs
are likely to persis at FKL/DUJ into Sunday afternoon. Another
crossing disturbance may bring rain and snow to the region on
Tuesday.

&&

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

&&

$$

SYNOPSIS...Frazier/MLB/CL
NEAR TERM...MLB/CL
SHORT TERM...CL
LONG TERM...Frazier
AVIATION...Rackley