649
FXUS61 KPBZ 300513
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
113 AM EDT Sun Jun 30 2024

.SYNOPSIS...
Renewed showers and storms develop late tonight. A cold front
moves across the region Sunday morning, with high pressure
building in its wake to start the week.

&&

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

- Scattered showers and possible storms through Sunday morning.
-------------------------------------------------------------------

Latest (Overnight) Update...
Minor adjustments made to temperature forecast overnight through
early Sunday morning. Current temperatures are still in the
upper 70s to around 80 at a lot of locations, and dewpoints
across the region continue to hover in the low 70s. With little
change expected in the latter conditions, expect low temps to
remain several degrees above what guidance is suggesting (low
70s for most; upper 60s still possible in the ridges). The rest
of the forecast remains on track. Previous discussions can be
found below.

Previous (Evening) Update...
The latest mesoanalysis shows ML CAPE values decreasing across
the region. Shear remains elevated, though with no significant
forcing for ascent it appears the severe weather potential has
diminished. Will let the current Severe Thunderstorm Watch
expire at 10 PM. Another shortwave, and associated surface cold
front, will approach the Upper Ohio Valley region late tonight.
This should generate isolated to scattered showers and possible
thunderstorms across the region. A few strong storms will be
possible as the front approaches.


Original discussion...
PoPs have been updated to reflect latest expectations. Storms
across nrn WV will continue for an hour or two as they translate
ewd and across the mountains. Blowoff from storms near KILN
also may eventually graze Muskingum County in OH. An upswing in
storm coverage in the far srn zones (nrn WV to near the Mason-
Dixon Line is increasingly probably late tonight/pre-dawn
tomorrow, and may expand in coverage with approach and passage
of the cold front Sun morning.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Cold front moves through Sunday morning.
- A few storms may be strong along it south and east of Pittsburgh.
- Drier air builds in with cooler temperatures.
-------------------------------------------------------------------

The cold front itself then moves through Sunday morning and carries
an additional lower confidence severe threat. Unfavorable mid to
late morning timing with at least some degree of cloud cover around
as even the lower end of the latest ensemble guidance indicates 40-
50% sky coverage through the morning hours lends less of a severe
threat, though that said, can`t rule out some stronger storms
capable of damaging wind southeast of Pittsburgh where a Marginal
Risk (1/5) remains.

We then finally get a push of drier air behind the front on Sunday
afternoon and evening as high pressure builds across the Great Lakes
and reinforces northerly flow in the wake of the boundary. Still a
bit of discrepancy in the 12z guidance on the timing of the front;
highs will be dependent on said timing as a quicker boundary could
keep PIT in the upper 70s while a slower push could result in mid
80s. Either way, clouds will scatter into Sunday evening, though a
passing upper wave looks to reinforce cloud coverage toward morning
on Monday. Still, overnight lows will be refreshing dipping into the
50s for most, though some 40s are possible (50-70% chance) in
the ridges and north of I-80.

Dry weather continues with high confidence through Monday night as
heights begin to rise and high pressure moves further east.
Temperatures remain below average on Monday with ensemble
probability <30% of highs topping 80 degrees.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
KEY MESSAGES:

- Dry weather continues Tuesday with increasing temperatures.
- Showers and thunderstorms return Wednesday and Thursday with
  another low pressure system.
-------------------------------------------------------------------

Good agreement amongst the various ensemble clusters supports dry
weather on Tuesday as ECONUS ridging builds. Temperatures begin to
rebound as flow becomes more south of east and pushes highs back
toward or a couple degrees above normal.

By mid-week, the pattern becomes more unsettled as ensembles break
the ridge down and low pressure moves by to our north. Deep
southwest flow on Wednesday surges temperatures back to 5-10 degrees
above normal, though timing of a cold front passage may throw a
wrinkle in that. Ensembles show increasing deviation from the mean
come Wednesday night through the remainder of the week, so
confidence is lower, but a cold front looks to pass through sometime
late Wednesday into Thursday returning shower and thunderstorm
chances. Machine learning becomes more interested in severe chances
by mid-week as the front pushes into a warm, moist airmass, so this
will bare watching through the coming days.

&&

.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
Scattered showers, with isolated thunderstorms south of PIT,
will continue this evening as a shortwave trough crosses the
Upper Ohio Valley region. The threat for thunderstorms elsewhere
continues to diminish, with weak forcing for ascent. VFR is
expected for much of the evening outside of any thunderstorms.

Expect MVFR/local IFR cigs late tonight with low level moisture
in place. In addition, scattered showers and possible
thunderstorms are expected late tonight/early Sunday morning as
a cold front crosses the region. MVFR will continue until mixing
and dry advection lift cigs back to VFR by Sunday afternoon.
Wind gusts should also increase after FROPA, with gusts to 20kt
Sunday afternoon.

.Outlook...
Outside of early morning river valley fog, VFR is expected until
a slow moving front sets up across the region Wednesday and
Thursday.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...Cermak/Kramar/WM
SHORT TERM...MLB
LONG TERM...MLB
AVIATION...WM