-- Discussion containing changed information from previous version are highlighted. --
365
FXUS61 KPBZ 180548
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
148 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 /UNTIL 6 AM THIS MORNING/...
KEY MESSAGES:

- Warm low temperatures are expected overnight.

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

Midnight Update:
All but a single lingering light shower has dissipated as
instability wanes. A mostly quiet overnight period is expected.
Latest HRRR model runs continue to indicate spotty morning
convection over easter Ohio near 12z, but this seems to be
overdone. Convective activity, outside of a stray morning
shower/storm, is likely to hold off until Tuesday afternoon.

Overnight temperatures will remain elevated, in the upper 60s
to lower 70s, with the lingering moisture.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
KEY MESSAGES:

- Heat continues to build through midweek.
- Isolated storms possible Tuesday afternoon.
- Dry and hot Wednesday.

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Ridge will continue to amplify on Tuesday, with the center of
the surface inflection pivoting westward with time through
Wednesday. Given how efficient heating has been today, think
Tuesday will be much of the same, if not even hotter given the
rising heights aloft. At this time, the probability of > 95 is
around 25-35% with near 70% in the urban areas.

As we will still remain on the periphery of the building ridge,
weaknesses riding along the ridge will maintain at least low
end chances for showers and storms. Also, the southeasterly
surface wind will enhance orographic effects which could be
enough to overcome the subsidence from the very strong ridge. If
convection does fire Tuesday afternoon, outflows from storms
could run down the western side of the ridges and develop more
activity away from the mountains. This threat should come into
better focus over the next couple of model runs.

Ridge will be firmly in place by Wednesday with ensembles
showing heights of 597-599dm. Given the region will be centered
in the ridge, the threat for convection should decrease. The
probability of temperatures > 95 degrees is even higher on
Wednesday with 40 to 60% covering most of the region outside of
the mountains; near 90% in the urban areas.

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.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
KEY MESSAGES:

- High confidence in a dangerous heat wave holding through the
  end of the week with heat impacts possible.
- Probabilities are pointing to Thursday and Friday being the
  hottest days of the week.

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The highly anomalous ridge will remain in place Thursday, but
ensemble data is now hinting the ridge will begin to slowly weaken
on Friday.

Thursday and Friday should be dry as the area will remain under
the influence of the ridge`s subsidence.

Probabilities for high temperatures > 95 both Thursday and
Friday are the highest of the week. The higher probabilities
are also spread out more Thursday and Friday. Generally looking
at probs of 50 to 80% both days.

With surface dewpoints remaining in the upper 60s to lower 70s,
heat indices will continue to hold right around 100 degrees.

This would mean at least 5 days of daytime heat indices near 100
degrees.

Considering heat effect will be cumulative, late week is looking
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.

This certainly is increasing slightly that there will be some
relaxation to the heat by early next week, but any relaxation
will still leave temperatures well above average. In the
Saturday-Sunday timeframe, all clusters reflect some flattening
of the ridge, but disagree on the degree of flattening. Some
maintain zonal flow or perhaps even weak eastern troughing early
next week, but even the coolest scenarios have temperatures
around average to start next week. The warmest scenarios
maintain near-record heat. SHould we stay quasi-zonal into next
week, we may get slight relief, but there as a notable fraction
on ensemble guidance that redevelops eastern ridging. CPC
maintains a moderate risk of excessive heat through 6/24.

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

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Expect mainly VFR conditions through the night and into the
dawn hours of Tuesday morning. Moisture produced this past
evening and afternoon from thunderstorms may result in some fog
development in the usual areas. This may impact terminals but
confidence is low in this occurrence. A weak surface trough
that has been the culprit for the area will remain in place into
the coming day as well. In fact, expect the chance of a few
showers developing and moving north into eastern OH through
dawn.

Heading into the day, any impacts to terminals 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 heading into Tuesday afternoon. 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/34
NEAR TERM...Rackley/34
SHORT TERM...22/34
LONG TERM...22/34
AVIATION...Shallenberger
CLIMATE...