-- Discussion containing changed information from previous version are highlighted. --
899
FXUS61 KPBZ 181154
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
754 AM EDT Tue Jun 18 2024

.SYNOPSIS...
A prolonged period of hot temperatures is expected with high
pressure. Hottest temperatures are anticipated Wednesday
through Friday. Isolated showers and storms are possible
Tuesday.

&&

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

- Heat continues to build, with many locations reaching 100F
  heat indices this afternoon.
- Isolated to scattered downbursts are possible once again this
  afternoon.

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

A warm but quiet morning across the Ohio Valley. A few speckles
of showers continue to show on radar to our south, but this
activity should stay out of our area.

The ridge will continue to amplify today, with surface high
pressure centered off the east coast. Rising heights aloft
should boost temperatures a few degrees higher than on Monday,
with the probability of >95F around 35-45% in many areas and
above 70% in urban areas. The heat advisory continues...

Similar to Monday, a weak disturbance riding the western
periphery of the ridge may help trigger convective initiation
again this afternoon. Despite strong subsidence from the ridge,
orographic effect and a minefield of outflow boundaries from
Monday`s storms could once again allow scattered thunderstorms
across the area. Rapid destabilization resulting from strong
surface heating along with weak shear will favor downbursts once
again, with potential for severe winds. SPC has highlighted much
of the region in a Marginal (1/5) risk.

Given the unknowns of initiation and complexity of the outflow
boundaries currently lying across the area, location and
coverage of storms is difficult to pinpoint. Best timing once
again appears to be in the mid/late afternoon, with storms
quickly diminishing in the evening hours.

&&

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

- Heat continues to build with probabilities pointing to
  Thursday and Friday being the hottest days of the week.
- Chances for afternoon convection decreases.

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

The ridge becomes centered over the region by Wednesday, with
ensembles continuing to show heights of 597-599dm. With surface
high pressure centered a little farther west, the threat for
convection will be decreased Wednesday afternoon, through
ensembles do indicate low-end probabilities mainly north and
west of Pittsburgh. For this reason, did introduce low-end PoPs
primarily across the I-80 corridor for Wednesday afternoon.
Probabilities for storms look even lower on Thursday and Friday
afternoons, but remain non-zero. Focus again would likely be
north of Pittsburgh.

With similar conditions, temperatures on Wednesday look to be
similar to Tuesday. Probabilities for high temperatures > 95
both Thursday and Friday are the highest of the week, though the
ridge will begin to break down on Friday. The higher
probabilities are also more widespread Thursday and Friday, with
much of the area in the 50-85% range both days.

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.

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 MONDAY/...
KEY MESSAGES:

- Hot temperatures continue into the weekend, but the heat wave
  will begin to break.
- Cooler temperatures are possible, at least temporarily by
  early next week.

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

The upper level ridge will break down this weekend and become
suppressed well to the south as an upper trough crosses the
Great Lakes. However, ensembles indicate this is unlikely to
have a significant impact on Saturday`s temperatures, with hot
weather continuing into the first half of the weekend.

Ensembles show good agreement on the upper trough crossing into
the Great Lakes by Sunday, which should finally bring relief
from the heat and an increase in rain probabilities. At present,
Sunday`s temperatures still appear well above average, but much
more tolerable than prior days. Post frontal cold advection on
Monday may finally drop temperatures back to a semblance of
normal, at least temporarily.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...

-- Changed Discussion --
Any impacts to terminals today will be solely due to
thunderstorms. However, the lack of strong forcing and multiple
boundaries put down by the convective activity from the previous
day will lead to less confidence in timing and location of
development. With daytime heating and remnant boundaries,
expect initiation to take place between 16Z and 18Z. Convection
is expected to then persist into the late afternoon and evening,
possibly dissipating earlier than the previous day by 00Z. Thus
have put VCTS to all terminals today to account for the
uncertainty in location ands timing. Once again, conditions due
to fog tomorrow night will be dependent on location of
convection. Expect light and variable winds through the day with
the exception of thunderstorms.

.Outlook...
High probability for VFR and dry weather through the week as
strong ridging develops aloft.

The only variance may come with isolated afternoon convection
on Wednesday, but upper ridging should suppress coverage and
potential initiation.
-- End Changed Discussion --

&&

.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:

Pittsburgh, PA:       98F  (1988)
Wheeling, WV:         100F (1933)
Morgantown, WV:       99F  (1893)
New Philadelphia, OH: 99F  (1988)
Zanesville, OH:       101F (1988,1934)
DuBois, PA:           92F  (1969)

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

Tuesday, June 18th
Pittsburgh, PA:       97F  (1994)     73F  (1905)
Wheeling, WV:         95F  (1944)     71F  (2018)
Morgantown, WV:       95F  (1994)     70F  (2018)
New Philadelphia, OH: 95F  (1994)     72F  (2017)
Zanesville, OH:       99F  (1944)     73F  (1944)
DuBois, PA:           89F  (2018)     69F  (2018)

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 Friday for PAZ007>009-013>016-
     020>022-029-031-073>078.
OH...Heat Advisory until 8 PM EDT Friday for OHZ039>041-048>050-
     057>059-068-069.
WV...Heat Advisory until 8 PM EDT Friday for WVZ001>004-012-021-
     509>511.

&&

$$

SYNOPSIS...Rackley
NEAR TERM...Rackley
SHORT TERM...Rackley/22
LONG TERM...Rackley/34
AVIATION...Shallenberger
CLIMATE...