-- Discussion containing changed information from previous version are highlighted. --
883
FXUS61 KPBZ 171858
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
258 PM EDT Mon Jun 17 2024

.SYNOPSIS...
Building high pressure will bring a prolonged period of hot
temperatures, lasting through the week. Hottest temperatures
are anticipated Wednesday through Friday. Isolated showers and
storms are possible this afternoon and again on Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
KEY MESSAGES:

- Heat begins to build in across the region.
- Weak shortwave may stir isolated showers/storms this afternoon
  with the potential for a few storms to have strong/severe
  wind gusts.

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

Building eastern CONUS ridge will bring quite the stretch of hot
temperatures to the region, with the potential to break heat
records, as noted in the Climate section below. Much of the
region has already exceeded 90 degrees, with the heat indices
nearing 100 as of this writing, despite the increasing cu. As
noted prior, ACAR soundings and the latest mesoanalysis
indicate plenty of instability and modest shear for thunderstorm
development. Storms have already begun to develop along a plume
of 70 dewpoints over northern and western OH with a few cells
beginning to pop north of Pittsburgh. Steep low level lapse
rates an notable DCAPE indicate that there is a severe wind
threat in storms that can maintain themselves, which is in line
with SPC`s marginal risk for severe storms through this evening.
Given the influx of moisture on the periphery of the building
ridge, PWAT values are also increasing, so heavy downpours are
also possible.

Convection should diminish after sunset this evening, but low
temperatures will remain elevated given the ridge in place.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
KEY MESSAGES:

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

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

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.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
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.

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

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 /18Z MONDAY THROUGH SATURDAY/...
Building high pressure will keep VFR conditions with light winds
in the forecast through the TAF period. The exception to this
may be isolated storms this afternoon as a weak shortwave
passes. However, strong subsidence with the building ridge is
likely to limit convective development, and with weak flow,
confidence is low on the location of any storms that do form.
Due to low probability and low confidence of
occurrence/location, have opted to not mention impacts in the
TAFs with this package.

.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 Tuesday, but upper ridging should suppress coverage and
potential initiation.

&&

.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:

Monday, June 17th
Pittsburgh, PA:       95F  (1994)     75F  (1892)
Wheeling, WV:         99F  (1936)     69F  (2004)
Morgantown, WV:       95F  (1967)     72F  (1939)
New Philadelphia, OH: 95F  (1967)     69F  (2022)
Zanesville, OH:       99F  (1936)     72F  (1994)
DuBois, PA:           89F  (1994)     66F  (1892)

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...34
NEAR TERM...34
SHORT TERM...22/34
LONG TERM...22/34
AVIATION...Rackley/88
CLIMATE...