902
FXUS61 KPBZ 140734
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
334 AM EDT Fri Jun 14 2024

.SYNOPSIS...
A cold front will bring scattered thunderstorms on Friday, some
could be strong to severe. Dry with seasonable temperatures
Saturday ahead of a high confidence, potentially historic,
prolonged period of dangerous heat next week.

&&

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

- Cold front will bring showers and thunderstorms with a 1/5 risk
  for severe weather.
- Temperatures right around normal.
-------------------------------------------------------------------

Convection off to our west overnight has thrown convective
debris clouds over the area as a few scattered and light
showers move through. Most will remain dry through this morning
ahead of a cold front and an upper wave that will sag through
later today with showers and thunderstorms developing along the
boundary. Latest hi res ensemble guidance suggests an initial
batch may move across eastern Ohio and western Pennsylvania
around noontime with weak convergence ahead of the boundary.
Should it materialize, it will exist in an environment that
hasn`t had much time to destabilize with instability maxing out
around 700 J/kg so this shouldn`t be too impactful. The front
itself will then move through and try to reinvigorate additional
development along it, but the wrinkle would be if there is any
earlier rain/cloud cover it may limit how much the atmosphere
can recover. Most likely ensemble timing of the front to the
Pittsburgh metro is in the 3-4pm window when the ensemble
probability of >1000 J/kg of CAPE and >30 knots of shear only
sits around 30-40%, likely a byproduct of its earlier
convection.

Primary threats will be damaging wind and hail, and the entire area
is outlined in a 1/5 risk for severe. With ensemble mean
precipitable water values nearing 1.4-1.5", any shower or
thunderstorm could bring a heavy downpour with it as well, so some
isolated flooding concerns can`t be ruled out.

A push of drier and cooler air will arrive in northwest flow behind
the front and drop lows Friday night to a couple ticks below normal.
Could see some areas of river valley fog develop.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Dry weather Saturday and Sunday.
- Near normal temperatures Saturday with a jump to 5-10 degrees
  above normal on Sunday.
-------------------------------------------------------------------

Heights rise into Saturday as upper ridging builds and surface high
pressure slides in to the north. Temps won`t rebound much in
northerly flow in the wake of the boundary and dew points will
likely mix out some in the afternoon with a dry boundary layer
providing a pretty comfortable day.

Upper ridging begins to build stronger making a run at 588-590dm by
Sunday to kick off the first day of increasingly hot conditions.
Surface high pressure establishes off to our east and southwest flow
on the west side of the 850 mb ridge axis will induce warm
advection with ensemble 850 temps up to 15-17C. This will
support widespread upper 80s with even a 40-70% chance of 90F+
for Pittsburgh south and west.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
KEY MESSAGES:

- High confidence in a dangerous heat wave setting up early next
  week with major heat impacts possible.
-------------------------------------------------------------------

Guidance has been consistent that a potentially-historic ridge will
continue to strengthen across much of the central and eastern CONUS
into the middle of next week. WPC ensemble clusters are highly
consistent through Tuesday, indicating high confidence in the
temperature forecast. Near-record breaking heat will build in to
start off next week.

Sunday will bring minor to moderate heat risk across the area as
surface high pressure establishes off to our east and highs make a
near 10 degree jump from Saturday. Significant heat is looking
increasingly likely with this anomalously strong ridge, especially
Monday and beyond, when major to extreme heat risk is likely. NBM
probabilities for high temperatures reaching 95+ degrees continue to
go up, and are now widespread 60-90% across the area. These higher
probabilities are especially prevalent in lower elevation areas
(e.g., river valleys) and urban centers, which tend to be warmer
than surrounding areas. In addition, dewpoints are currently
forecast to remain in the mid 60s to lower 70s, which would result
in high enough humidity levels to support heat indices climbing to,
and potentially exceeding, 100 degrees. If dew points do hold toward
the lower end of that spectrum, we may be able to make a run at 100
degree air temperatures Monday and beyond (last time at PIT was
7/15/95); NBM probabilities for that threshold are now up to 60% on
Tuesday with ~50% chance for the remainder of the week. Only acting
to exacerbate the prolonged heat effects will be a 60-80% chance of
low temperatures greater than 70 degrees through the end of the
week. Heat impacts will need to be closely monitored and headlines
may need to be considered.

Three out of four clusters maintain at least a 594dm ridge through
June 22nd with the one exception being a lower probability solution
than the others. Return intervals of these heights dating back to
1979 are just about out of the climatological range. CPC suggests
that excessive heat may last through June 24th, indicating the
potential for a long-duration excessive heat threat. The last
comparable, long-duration heat event was from July 1994.

Impacts include heightened heat-related illnesses and potential
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.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
VFR conditions prevail throughout much of the TAF period. A
late morning/afternoon cold front will be the focus for
convection. At this time, confidence is low that any shower or
storm will hit a port. For the forecast, will introduce prob30
at each port during the time period when probabilities for
convection are highest. Any convection may cause a brief
reduction in vis and cig height.

In the wake of the front, winds shift to northwesterly and
skies begin to clear again as drier air moves into the region.


.Outlook...
Restrictions in showers and thunderstorms will be possible
through Friday with a passing cold front. Largely VFR
conditions are then forecast Saturday through Tuesday.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...MLB
LONG TERM...MLB/Milcarek
AVIATION...22