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259
FXUS61 KPBZ 161513
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1113 AM EDT Sun Jun 16 2024

.SYNOPSIS...
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A prolonged and potentially dangerous heat wave is anticipated
this week. A Heat Excessive Watch is in effect Monday through
Friday.
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&&

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

- Today begins the first day of abnormally warm weather as ridge
  axis builds across the East Coast.

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

Dry, quiet, and warm weather is expected today as ridge axis,
currently situated over the Southeast, extends north. Deep
mixing of dry warm air will prompt temperatures in eastern
OH/northern WV to peak near 90F today. Probability of ZZV/MGW
reaching >= 90F ranges between 60% to 70%.

After 3pm, low-level winds will veer southeast to south and
advances low-lvl moisture north into western PA. Therefore,
overnight low temperatures will range in the low to mid-60s,
about 5 degrees above the climatological average.
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&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
KEY MESSAGES:

- Dry weather continues.
- Noticeably warmer temperatures on Sunday.
-------------------------------------------------------------------

A dry and balmy night is expected, with lows in the mid and
upper 60s.

Latest ensemble data shows a continued amplification of the
ridge on Monday, with 591dm building to the north of the
forecast area. The forecast headache Monday is the risk for cu
development and scattered showers and storms. Deterministic
models are showing a weak shortwave moving northeastward over
top of the ridge, leaving SW Ohio Monday morning and reaching
SW PA during the afternoon. The response to this wave is at
least an increase in cu with the risk for isolated to scattered
showers and storms. Ensemble data is indicating measurable
precipitation across much of the region sometime Monday,
although this will be overdone as the activity will be
mesoscale. But even some of the CAMS are showing popup shower
and storms Monday afternoon across a large portion of the area.
Models are in agreement that the atmosphere will become unstable
Monday afternoon, but this is to be expected with surface
dewpoints rising into the upper 60s to lower 70s. Models are
also in line with very warm air aloft overspreading the area.
+16c to +18c at 850mb and +9c to +11c at 700mb. So even though
the atmosphere is unstable, those are very warm temperatures
aloft which should provide an atmospheric cap Monday afternoon.
Additionally, there is the highly anomalous ridge providing
strong subsidence as it continues to amplify.

Latest NBM probs for measurable rainfall are generally 30 to 40%
across the entire area Monday. This seems high when factoring in
everything working against convection. The ridges may be the
place to watch as the low-level flow would bring orographic
lift into the equation which could be enough to overcome those
limiting ingredients. CAMS and deterministic models are focusing
more on the ridges Monday afternoon.

So if we do see an increase in clouds or perhaps convection,
this will obviously effect Mondays temperatures. Seeing this in
the latest model data as well. Latest NBM has lowered
probabilities of >95 degrees on Monday for much of the region,
focusing the higher probs in low-lying and rural areas. It will
still be hot, but not maximizing the potential just yet.

Ridge continues to amplify on Tuesday as we see heights of
594dm-596dm across the region. 850mb temperatures continue to
rise as well as +18C to +20c spreads northward across the entire
forecast area. Still seeing indications of a shower/storm threat
Tuesday as more waves of energy rotate overtop of the ridge.
However, the NBM has shifted focus for activity on Tuesday
further north toward the I-80 corridor as everything is forced
northward due to the expanding 500mb heights. The story for
activity Tuesday remains the same as Monday, but the area under
the threat has decreased.

So what does that mean for temperatures Tuesday? With the
strengthening ridge and warming aloft, would think that cu
coverage, for most of the region, would decrease on Tuesday,
which should translate into hotter surface temperatures. This is
showing up in the NBM probabilities for highs >95 degrees.
Probs of 50-70% have spread across most of the region, outside
of the mountain tops and even starting to see probs of >98
degrees in low lying and rural areas. So this will be a building
heat that should increase from Monday into Tuesday.

&&

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

- High confidence in a dangerous heat wave holding through the
  week with major heat impacts possible.
- Seeing some timing differences on when the hottest air
  arrives.
-------------------------------------------------------------------

The numbers and timing of the most extreme heat continue to
evolve, but our overall expectations have not changed for this
period. We are looking at a potentially historic heat wave for
Pittsburgh and the Upper Ohio Valley, with impacts to public
health and utilities a possibility.

Model cluster analysis continues to paint a high-confidence picture
of the overall pattern. An anomalously strong 500 mb ridge will
persist over the eastern CONUS through Friday and possibly into
early Saturday, reaching its peak during the Wednesday/Thursday
period, before potentially becoming a bit more muted Saturday.
Both the EPS and GEFS means have 500mb heights of 597dm or
higher during that period. This sets the stage for a prolonged
period of high temperatures well into the 90s. NBM probabilities
of highs >95 increase and expand both Wednesday and Thursday,
with probabilities >100 sneaking in Thursday. There is a
possibility that these values are underdone. Given the
strength/position of this ridge, precipitation chances and cloud
development are quite low, especially during the Wed-Fri
period, which will cause an increasing dry surface, promoting
higher temperatures. Given that sun angles are at their annual
peak, insolation will add another warming factor. This will be a
building heat, that will slightly increase each day.

When considering dewpoints, heat index values in the 100 to 110
range are in the cards for a few days.  There does remain some
uncertainty in how widespread and long-lasting these kind of heat
index values will be from day to day. This normally has
implications for what kinds of heat-related headlines would be
appropriate. However, we feel that this event will have a length
and impact that the standard criteria may not capture. So the
Excessive Heat Watch will remain in place for the entire
forecast area Monday through Friday.

There are still uncertainties with the forecast. But signals
this impressive do not come around very often.

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. Gather food,
water and medication now. Make a list of friends and family to
check on and help them prepare. Strongly consider rescheduling
outdoor events. 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.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
VFR conditions and light winds prevail throughout the TAF period
under building high pressure.

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

The only variance may come with isolated afternoon convection
starting Monday, but upper ridging should suppress coverage and
potential initiation.

&&

.CLIMATE...
The area has the potential to break various heat-related
records. In this climate section, we will attempt to address
some of the higher-profile historical temperature records.

First, we cannot rule out that some sites approach all time
record high temperatures:

Pittsburgh, PA:       103F (7/16/1988, 8/6/1918, 7/10/1881)
Wheeling, WV:         106F (7/22/1934, 8/6/1918)
Morgantown, WV:       105F (8/26/1893)
New Philadelphia, OH: 102F (7/17/1988)
Zanesville, OH:       106F (7/14/1936, 7/25/1934)
DuBois, PA:           101F (07/22/2011)

There is moderate 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)

Due to the how early in the summer this heat wave is, there
is a high 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)

Due to the duration of the heat, sites will also approach records
for consecutive days greater than 95F (dates are the day the
streak ended):

Pittsburgh, PA:       6    (6/20/1994, 8/11/1900)
Wheeling, WV:         8    (7/15/1936)
Morgantown, WV:       9    (9/16/1997, 7/19/1892)
New Philadelphia, OH: 5    (7/27/2016, 7/10/1988)
Zanesville, OH:       9    (9/4/1953)
DuBois, PA:           3    (7/9/1988)

And it should go without question that 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...Excessive Heat Watch from Monday morning through Friday
     evening for PAZ007>009-013>016-020>022-029-031-073>078.
OH...Excessive Heat Watch from Monday morning through Friday
     evening for OHZ039>041-048>050-057>059-068-069.
WV...Excessive Heat Watch from Monday morning through Friday
     evening for WVZ001>004-012-021-509>514.

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...22
LONG TERM...22/CL
AVIATION...Cermak/Rackley
CLIMATE...