998
FXUS61 KPBZ 132325 AAD
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
725 PM EDT Sat Jul 13 2024

.SYNOPSIS...
A more active weather pattern featuring increased thunderstorm
chances and the potential for severe weather is favored starting
Sunday evening through Wednesday. Heat risks will remain
elevated during this period as well. Dry and seasonable weather
is likely late next week after the passage of a cold front.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
KEY MESSAGES:

- Above normal temperature will continue with plentiful sunshine.

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Evening update...focusing mainly on area of thunderstorms moving
across the northern CWA. These storms are pulsing then falling
quickly. Should dissipate after sunset. Overnight temperatures
were updated as well.

Overnight lows will run about 5 degrees above average.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Increasing heat risk expected as temperatures sit 5 to 10
  degrees above the daily average.

- A more active pattern begins Sunday with a series of crossing
  shortwaves and possible MCSs.

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Weak warm advection is expected Sunday as the surface ridge
subtly shifts southeastward in response to a shortwave trough
crossing the western Great Lakes. This will increase daytime
temperatures with much of the area making it into the low to mid
90s. A few locations may near 100F heat indices, though this is
low probability.

Considerable uncertainty remains with the evolution of an MCS
crossing out of the upper Midwest and into the Ohio Valley
Sunday afternoon. CAMs are in agreement with a weakening trend
as this feature pushes southeast into our region, owing to
continued warm air aloft and a relatively dry environment. It is
possible that Sunday evening may remain dry or see little more
than light rain showers with increased cloud cover. However,
significant variations exist in how quickly these storms fall
apart and the timing. The SPC Day 2 Outlook extends a marginal
risk (1/5) just into our eastern Ohio counties.

Crucially, this first shortwave/decaying MCS is pegged by models
to help erode/cool the warm air aloft and prime the region for
additional shortwave movement Monday. Ensembles are trending
toward higher probabilities for showers and thunderstorms ahead
of that wave Monday, but much variation remains (and will be
tethered, in part, to upstream convective evolution). General
consensus still favors an afternoon timing where mean SBCAPE
values will range from 2000-3000 J/kg, weak shear and DCAPE
values around 1000 J/kg. These would indicate a damaging wind
(and lower probability hail threat) environment via either
individual storm clusters or a secondary MCS. However, at least
one CAM favors morning convection across the area before a more
robust MCS Monday evening. Morning/early afternoon convection
could certainly throw a wrench in more organized evening storms.

Timing and presence of convection will also greatly determine
the extent of potential heat risks. The lack of convection and
cloud cover through a portion of the afternoon could foster mid
90s highs with rising dewpoints, creating fairly widespread
heat indices above 100F; early convection and/or lingering
cloud cover may make it difficult to even hit 90.

&&

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

- Active weather with the potential for severe hazards remain
  possible Tuesday into Wednesday until the passage of a cold
  front.

- Heat risks could be maximized Tuesday, but will be dependent
  on convective evolution and resultant cloud cover.

- Dry weather and seasonable temperature are likely to end the
  work week.

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Ensembles favor additional shortwave movement south of a
deepening upper level trough north of the Great Lakes Tuesday
into Wednesday. The more well developed trough is then favored
to push a cold front through the region Wednesday
afternoon/evening and position broad upper troughing over the
Great Lakes to end the work week. In a broad sense, this pattern
lends to a peak in hot/humid conditions and potential severe
weather Tuesday; peak shower/thunderstorm chances Wednesday with
frontal passage; and dry weather with seasonable temperature
Thursday into Friday.

It remains difficult to discern thunderstorm coverage, timing
and the scope of potential severe threats as subtle variations
in shortwave positioning and potential weak ridging between
waves remains large among ensemble model solutions. As has been
previously stated, prior days` convective evolution will have
significant influence on Tuesday`s/Wednesday`s outlooks. But
awareness of potential hazardous conditions remains a necessity
as there is a potential widespread damaging wind threat and/or
fairly widespread heat advisory day Tuesday. The best course of
action will be to continue to monitor the latest updates and see
what trends in model depictions suggest.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Mainly VFR conditions are forecast over the next 24 hours as
high pressure remains in control. Would expect fog at FKL later
tonight as they received rain earlier.

Sct to bkn cu will develop again on Sunday. Currently the threat
for any afternoon or evening showers or storms to develop and
hit a port is low, so have left out of the forecast.

.Outlook...
The likelihood of restrictions with convection will increase
Monday and Tuesday.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Rackley
SHORT TERM...Rackley
LONG TERM...Rackley/Frazier
AVIATION...CL