104
FXUS61 KPBZ 221602
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1202 PM EDT Sat Jun 22 2024

.SYNOPSIS...
Dangerous heat continues today with severe weather possible
tomorrow afternoon; the primary threat remains wind, although
hail and tornadoes are possible. A brief "cool down" is
expected through Monday before temperatures increase yet again.

&&

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

- Excessive Heat Warning and Heat Advisory remain in effect
  until 9pm.
-------------------------------------------------------------------

Temperatures have already risen into the upper 80s and lower 90s
area-wide as we mix up to roughly 700mb, as indicated by the
morning sounding. Temperature rises through this afternoon will
remain a bit slower to rise as the boundary layer continually
erodes into the 700mb cap.

Cumulus has started to form across the area as we tap into the
LCL, but thus far development seems shallow under the initial
cap. With mixing, it is expected that these cumulus grow in
vertical extent, but development will be challenged past around
12kft with yet another elevated inversion. It will take repeated
updraft failures to cool the environment enough to mix into the
500mb-400mb layer, but even then, storms are expected to
encounter yet another inversion at 25kft. This will make it
difficult for mature updrafts to materialize, especially when
combined with notable dry air above the boundary layer. The
main area to watch, if any, will be the lake-shore. Much like
we have seen this week, we will rely on the lake boundary to
initiate convection which may alter the environment enough to
establish a cold pool and propagate southeast.

Into this evening and tonight, a pressure gradient will increase
a a Great Lakes low moves in. This will usher in light southwest
flow at the surface and finally begin to usher in a different
airmass. With the return of clouds tonight and light winds,
tonight may be the warmest night of the week with lows only
bottoming out in the low to mid 70s. This will keep conditions
uncomfortable for one final night. Some nocturnal
showers/storms may develop, primarily across northwest PA, with
increases in 700mb moisture and fumes of CAPE, although a
shallow inversion and little vertical development should keep
any concerns low.

&&

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


- Crossing cold front brings showers and thunderstorms Sunday
- Severe storms possible Sunday
- Return to seasonable temperatures on Monday
-------------------------------------------------------------------

Very warm temperatures will continue tonight as cloud cover and
southwest wind increase tonight ahead of an approaching cold
front. A shortwave trough, and the associated cold front, is
expected to approach the region Sunday. Most available model
output indicates a pre-frontal trough will cross the region
from mid morning through early afternoon, with the cold front
crossing through the late afternoon/evening.

Increasing instability and shear is progged through the day,
with ensemble based mean MU CAPE 1500-2000 j/kg by Sunday
afternoon/evening, with the max surface based CAPE 2000-3000
j/kg. 0-6km bulk shear values also increase to 35-40kt, with dry
mid level air enhancing downdraft CAPE. A low level jet from
35-40kt at 850mb will also enhance the damaging wind potential.

Curved hodographs in the lower levels also indicate some
rotation/isolated tornado potential. The Storm Prediction Center
has placed much of western PA in a Slight Risk for severe
storms. The main hazard is expected to be damaging wind, though
with the curved hodographs and shear isolated tornadoes are also
possible. The Slight Risk area is surrounded by a Marginal Risk,
where FROPA timing and shear profiles are slightly less
favorable for severe storms.

The cold front will complete its passage Sunday evening, with
showers and thunderstorms ending from W-E. Surface high pressure
is expected to build under a crossing upper trough on Monday.
This should return mainly dry, and more seasonable weather to
the region.

&&

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

-Above average temperatures return
-Mainly dry to start and end the work week, with shower and
 thunderstorms for mid week
-------------------------------------------------------------------

An upper ridge, ahead of an approaching Midwest trough, will
maintain dry weather on Tuesday. Rising 1000-500mb heights and
warm advection will drive temperatures from 5 to 10 degrees
above average.

The trough, and its associated surface cold front, will approach
and cross the region late Tuesday night through Wednesday
evening, with shower and thunderstorm chances returning. Building
high pressure will return dry weather for Friday, with
temperatures closer to average.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
High probability for VFR to persist through the TAF period under
the influence of high pressure. Warm, dry air aloft should limit
convective initiation and keep probabilities very low of
terminal impact with an afternoon thunderstorm.

Approach of an upper level shortwave and associated cold front
will increase thunderstorm chances at the end to after the TAF
period. Latest analysis suggests to waves of thunderstorms, the
first between 15-20z (11am-4pm EDT) along a pre-frontal trough,
and the second between 21z-03z (5pm-11pm EDT) as the cold front
advances southeast. Storm intensity (and probability of
terminal impact) is likely to be highest with the second wave.

.Outlook...
Lingering showers and low probability thunderstorms are possible
through early Monday morning amid cold advection and crossing of
the upper trough axis.  High pressure and northerly flow aloft
will establish dry and more seasonable conditions for the start
of the next work week.

&&

.CLIMATE...
The area has the potential to break various heat-related
records.

There is low probability that climate sites approach the
highest temperatures recorded in the 21st century:

Pittsburgh, PA:       98F  (7/7/2012)
Wheeling, WV:         98F  (7/7/2012)
Morgantown, WV:       101F (7/7/2012)
New Philadelphia, OH: 101F (7/7/2012)
Zanesville, OH:       101F (7/7/2012)
DuBois, PA:           101F (7/22/2011)

There is a low probability many June all-time temperature
records may be at stake:

PIT: 98F (1988)
HLG: 100F (1933)
MGW: 99F (1893)
PHD: 99F (1988)
ZZV: 101F (1988,1934)
DUJ: 92F (1969)  *RECORD TIED ON 6/18/24*

Daily high maximum (left) and high minimum (right) temperature
records are at stake for:

Saturday, June 22nd
Pittsburgh, PA:       98F  (1988)     75F  (1988)
Wheeling, WV:         95F  (1923)     72F  (2011)
Morgantown, WV:       96F  (1923,1988)73F  (1988)
New Philadelphia, OH: 97F  (1988)     71F  (1997)
Zanesville, OH:       99F  (1988)     71F  (1997)
DuBois, PA:           91F  (2022)     68F  (2022)

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT this evening for PAZ007>009-013-
     015-016-022-031-074-076>078.
     Excessive Heat Warning until 8 PM EDT this evening for PAZ014-
     020-021-029-073-075.
OH...Heat Advisory until 8 PM EDT this evening for OHZ039>041-
     048>050-057>059-068-069.
WV...Heat Advisory until 8 PM EDT this evening for WVZ001>004-012-
     021-509>511.

&&

$$

SYNOPSIS...Milcarek
NEAR TERM...Milcarek
SHORT TERM...WM
LONG TERM...WM
AVIATION...Frazier
CLIMATE...