647
FXUS61 KPBZ 191744
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
144 PM EDT Wed Jun 19 2024

.SYNOPSIS...
A dangerous heat wave will impact the region this week. A Heat
Advisory and Excessive Heat Warning are in effect through Friday.
This event is highly unusual for our region and could be worse
than the 1994 heat wave.

&&

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

- Excessive Heat Warning for the urban areas of western PA;
  Heat Advisory continues elsewhere.
- Heat index values ranging from 100F to 110F.
- Isolated to scattered thunderstorms possible again this
  afternoon with downbursts the primary threat.
-------------------------------------------------------------------

The ridge aloft will shift a bit further south today with the axis
extending back to the west and into the southern portions of the
forecast area. As a result, heights will modestly rise and this will
likely be enough to keep convection to a minimum across most of our
area. Cirrus coverage through the morning has precluded a lot of our
area from reaching convective temperatures yet, but some cumulus are
starting to pop along the ridges. Hi res ensemble probabilities and
latest CAMs favor development along the lake breeze and a
differential heating zone in north central Ohio where the cirrus
has scattered out, so coverage in our area should be less than
the past two days and confined north and west of Pittsburgh. The
threat will once again be damaging winds from downbursts with
up to 1300 J/kg of DCAPE, 2500-3000 J/kg MLCAPE, and up to 30
knots of effective shear present on mesoanalysis. Storms should
begin to pop after 17z with outflow boundaries keeping
convection going through the day. A Marginal Risk (1/5) remains
in place north of Pittsburgh. Precipitable water values remain
above 1.5", highest to the north, so localized heavy rainfall
under persistent thunderstorms is again possible.

Once again, expect heat indices to cross the 100 degree mark this
afternoon, especially in the urban areas and east of Pittsburgh as
aforementioned cirrus coverage has muted heating a bit across
eastern Ohio and western Pennsylvania. Heading into the overnight,
convection should wane by 00z. Localized patches of fog will be
possible again tonight and most likely in the river valleys.
Low temps tonight will once again be in the lower 70s to mid 70s
allowing for little relief from the heat overnight.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Confidence is high that hot conditions will continue through
  Friday, Excessive Heat Warning and Heat Advisory remains in
  effect.
- Chances for afternoon convection decreases but the better
  chance will continue to be more to the north of Pittsburgh.

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

The ridge axis remain situated across the East Coast through the
weekend. 500mb heights will range between 596 dm to 598 dm
on Thursday as the ridge extends into Newfoundland and Quebec.
Record breaking afternoon high temperatures and overnight
maximum low temperatures continue in this time period.

The hottest time period is expected to be Thursday into Friday
where mid-90s to upper-90s; the NBM 25th percentile suggests
low to mid-90s across the region.

Elevated high temperatures and dewpoints will keep heat indices
at and above 100 through the period. Low temperatures will also
remain elevated with the probability > 70 around 50-80% both
nights.

Considering heat effects will be cumulative, late week looks
particularly dangerous. The early season event, and temperatures
increasing slightly each day, will compound any existing heat
issues.

Potential impacts include heightened heat-related illnesses and
power grid issues with increased demand. It is strongly
encouraged to know where cooling shelters are located and stay
hydrated. There may be little relief at night. Make a list of
friends and family to check on and help them prepare.
Prolonged exposure to excessive heat was the primary cause of
weather-related fatalities in 2023. For our region, this heat
wave may be compared to our worse than June of 1994.

Please see the Climate section below for more numerical details on
the kinds of records that may be in jeopardy.

&&

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

- Hot temperatures are expected to continue into Saturday; heat
  products may need to be extended in the next 24 to 48 hours.
- Relief from the heat may return with a passing trough over the
  Great Lakes Sunday into Monday.
- A weaker ridge builds in after Monday.

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

The upper-level ridge will continue hot and humid conditions
into the region through Saturday. Heat products may need to be
extended.

Ensemble models project a trough forming over the Midwest and
ejecting into the Great Lakes Sunday into Monday that may bestow
some relief to the Ohio River Valley. Temperatures may still
remain above average, but Heat Advisories/Warnings may not be
necessary.

After the passage of the trough on Monday, another upper level
ridge begins to move over the Upper Ohio Valley region. Although
this ridge will likely lack the staying power of last weeks
ridge. That said, there is still a potential for greater than 90
degree temps.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Thunderstorms continue to look less likely this afternoon as
warm air aloft (indicated by latest aircraft obs and rapid
update soundings) should keep convection largely capped off.

Winds remain light and variable with a generally southerly
component.

.Outlook...
High probability for VFR and dry weather through the week as
strong ridging develops aloft. Restrictions with rain may return
late this weekend with a cold front.

&&

.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 modest 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:

Wednesday, June 19th
Pittsburgh, PA:       97F  (1994)     74F  (1905)
Wheeling, WV:         95F  (1933)     70F  (2021)
Morgantown, WV:       94F  (1994)     72F  (2018)
New Philadelphia, OH: 92F  (1994)     70F  (2018)
Zanesville, OH:       94F  (1994)     75F  (1897)
DuBois, PA:           87F  (2001)     66F  (1975)

Thursday, June 20th
Pittsburgh, PA:       95F  (1994)     78F  (1924)
Wheeling, WV:         97F  (1933)     70F  (1924)
Morgantown, WV:       99F  (1893)     75F  (1924)
New Philadelphia, OH: 95F  (1994)     71F  (2009)
Zanesville, OH:       98F  (1934)     75F  (1924)
DuBois, PA:           89F  (1991)     66F  (1996)

Friday, June 21st
Pittsburgh, PA:       95F  (1933)     73F  (1934)
Wheeling, WV:         99F  (1933)     69F  (2016)
Morgantown, WV:       95F  (1953)     72F  (1988)
New Philadelphia, OH: 94F  (1994)     72F  (2016)
Zanesville, OH:       97F  (1988)     72F  (1997)
DuBois, PA:           89F  (1991)     68F  (1988)

&&

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

&&

$$

SYNOPSIS...Shallenberger
NEAR TERM...MLB
SHORT TERM...Shallenberger
LONG TERM...Hefferan/Shallenberger
AVIATION...Rackley/Shallenberger/88
CLIMATE...SKH/CM