933
FXUS61 KPBZ 181747
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
147 PM EDT Fri Apr 18 2025

.SYNOPSIS...
Dry conditions with well above normal temperatures today. Shower and
thunderstorm chances return Saturday with a cold front and again
Monday. Severe weather is possible both days. The above normal
temperature trend continues into the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Dry with gusty wind and above normal temperatures.
- Enhanced fire danger this afternoon.
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The warm front is now moving through our area this afternoon as
a mid-level ridge axis amplifies and slides overhead. Not
expecting any precip with the frontal passage as it moves
through locally given antecedent low level dry air on our 12z
sounding and the best moisture remaining off to our north.
Strong warm advection in increasingly gusty southerly flow
will continue through the afternoon as will efficient mixing
into very dry air below 700 mb. This will have two notable
effects on the day today: 1) mixing down of a 35-40 knot low
level jet analyzed at 850 mb which, combined with a tightening
gradient, will produce gusts up to 30-40 mph; NBM prob 24 hour
max gust suggests a 50-80% chance of gusts >35 mph, highest in
the ridges and eastern Ohio. 2) a decrease in afternoon dew
points which will allow temperatures to soar well above normal
but also create enhanced fire weather concerns. Erring toward
the NBM 5th percentile for Tds through this afternoon to best
match observations and trends, minRH values will drop to the
20-30% range. In coordination with neighboring offices and state
fire partners, have issued an SPS through 8pm covering the fire
danger today.

Nudged up a from the NBM deterministic to the 90th percentile for
highs today as well given its lower MaxT bias on well-mixed
days which supports a rise into the upper 70s/low 80s with a
70-90% chance of hitting 80F from Pittsburgh and south.
Afternoon readings are already reaching the 80 degree mark south
of I-70. Record highs should be safe today as the bar is pretty
high at all of our climate sites (90F at PIT).

&&

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

- Marginal Risk (1/5) for severe on Saturday.
- Cooler but still around average on Sunday with dry weather.
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Most of the region will sit in a cloudy open warm sector through the
early morning hours tomorrow ahead of an approaching cold front that
may spark off showers and thunderstorms. The warm overnight
lows will give us a good launching pad for temperatures to start
off with tomorrow, but the limiting factor to the severe threat
may be said cloud coverage and scattered morning showers in
pre-frontal convergence. Initial development is likely ahead of
the front in the morning hours north of Pittsburgh in an
unfavorable time for severe weather with likely elevated
convection utilizing fumes of MUCAPE. Increasing moisture will
provide low 60s dew points by the afternoon with temps in the
70s, but taking a combined probability of CAPE >500 J/kg and
shear >30 knots provides highest probability (40-60%) south of
Pittsburgh. That looks to be the area with the best shot to see
some scattering of the clouds as some mid level drier air tries
to nose north as well as the area more free from morning precip.
HREF 10th percentile cloud coverage shows this possibility but
still keeps everywhere else across our area socked in with
clouds. The best chance looks to be along the boundary itself in
the mid- afternoon hours south of Pittsburgh with machine
learning showing a wind threat which is supported by the
straight forecast hodographs. SPC has maintained the Marginal
Risk (1/5) for eastern Ohio into western Pennsylvania.

Highs Saturday will be dependent on frontal timing and cloud
coverage with warmer values to the south. Non-convective wind will
be gusty as well into the 30-35 mph range with still a tight
pressure gradient and mixing into the departing low level jet.

&&

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

- Thunderstorms possible Monday with a cold front passage.
- Dry through mid-week with temperatures above normal.
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Upper ridging breaks down Monday as an upper trough slides through
the Great Lakes region. Ensembles differ some on the speed of it
with a quicker, though less likely, solution dominated by the GEFS.
Implications would reflect on the progression of the attendant
surface low following a similar track. A warm front will lift
through in the morning hours with a few hour difference between
clusters with faster overall system movement. Southerly flow behind
it will be enough to pump in better moisture with dew points into
the mid to upper 50s by afternoon. An earlier warm front
passage and more time in the warm sector typically points toward
increased chance for destabilization ahead of an approaching
cold front expected later in the afternoon, but we would have to
verify closer to the NBM 10th percentile cloud cover to get
enough scattering to generate stronger instability, which is a
less likely, but still possible, solution at this point. Deep
layer shear looks sufficient as a southwesterly 850 mb jet
encroaches from the west atop backed surface flow, so the
question will be the instability. Can`t rule out any hazard at
this point given the shear values, forecast hodographs, and
moisture return, but when CAMs come into play we should get a
better idea. CIPS analogs do hit on an elevated severe potential
across western PA and eastern OH, so will have to continue
monitoring over the weekend.

As the trough departs, flow becomes more zonal and broad high
pressure settles in. Dry weather looks to prevail through Wednesday.
Temps will take a bit of a hit on Tuesday behind the front, but with
highs still favored to reach the upper 60s. Our next chance for rain
will come on Thursday as disturbances in the flow move through, but
overall confidence on timing is low at this point.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions are forecast to continue through the evening, as
the region enters the warm sector behind a crossing cold front.
Some high-based cumulus/altocumulus are expected generally to
the north and west of PIT this afternoon, before clouds mostly
clear temporarily this evening. Gusty southwest wind, with peaks
of 20 to 30 knots, will continue into the evening.

Wind gusts will ease slightly tonight, but occasional peaks of
15 to 20 knots shall continue through the night, thanks to a
still-tight pressure gradient and ongoing mixing. Still, an
overnight low-level jet of 40 to 45 knots will be enough to
create low-level wind shear concerns at all TAF sites overnight.

Clouds are forecast to redevelop later tonight ahead of an
approaching cold front. Showers could then enter the region
after 06Z,, with FKL having the best chance of seeing rain
before sunrise. As the cold front settles towards the region, an
increase in shower coverage is anticipated. The early arrival of
at least elevated instability will create thunderstorm potential
starting during the late morning hours. There is some
uncertainty regarding exact coverage and timing, but VCTS was
included at all sites at the end of the TAF period to highlight
the threat. MVFR ceilings may also sneak into areas north of
I-80 prior to 18Z.

Outlook...
Showers, restrictions, and possible thunderstorms are expected
Saturday afternoon and night as a cold front tracks slowly SE
across the Upper Ohio Valley region. VFR should return Sunday as
the front drops south of the area.

Showers and restrictions are possible Sunday night as the front
moves back north as a warm front.

Showers are likely (with possible thunderstorms) on Monday with
a crossing cold front. VFR returns Tuesday under high pressure.

&&

.CLIMATE...
Record high lows may be challenged tonight. Below are the
records and current forecast values.

SiteRecord LowForecast Low
---------------------------------
PIT    65F          65F
ZZV         70F          65F
HLG         67F          65F
MGW         65F          65F
PHD         65F          63F

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...CL
CLIMATE...MLB